Patent Application
20210340011
The present disclosure relates to polymer electrolytes that can also serve as precursors to ceramic electrolytes for coating, binder, sintering aid, and adhesive applications for solid state electrolytes and methods for chemically synthesizing the polymers.
This section provides background information related to the present disclosure which is not necessarily prior art.
A well-established problem with cycling lithium ion batteries with any type of electrolyte is that during recharging, Li deposition can be non-uniform. For example, in a battery including an anode, a cathode, and an electrolyte layer disposed between the anode and the cathode, non-uniform Li deposition on an anode can result in a rapid growth of dendrites that can penetrate the electrolyte layer and form a bridge to the cathode. This bridge causes a short circuit that leads to catastrophic failure. Consequently, tremendous efforts have been directed at solving this problem.
In part, these efforts led to the development of ceramic electrolytes, e.g., Li1.3Al0.3Ti1.7(PO4)3 (LATP) and cubic-Li7La3Zr2O12 (c-LLZO), which were originally thought to offer a mechanical solution by physically blocking dendrite growth. However, these materials were found to suffer from other problems that have rendered them less than completely practical for battery applications. Indeed, LATP is susceptible to irreversible reduction during cycling and c-LLZO has been found to be susceptible to dendrite penetration along grain boundaries, which again leads to short-circuiting.
Because of these deficiencies, other solutions are sought to resolve these problems. To this end, a set of ceramic materials has been identified that appears to be resistant to dendrite penetration, that also wets with Li metal, and that offers sufficient ionic conductivity (>10−6 Scm−1) to permit use as interfaces with LATP and c-LLZO. These materials include the family of LiPON glasses, LixAlOy and LixZnOy, among others. However, a key problem with these materials is that their Li+ conductivities are very low. For example, whereas LATP and c-LLZO have conductivities of 2-6 mScm−1 and 0.2-2 mScm−1 (Al vs Ga doping), respectively, the ceramic materials have conductivities in the rage of 2-10×10−3 mS cm−1. Due to these low Li+ conductivities, the ceramic materials must be introduced as interface materials at thicknesses of 50-200 nm in order to offer practical Li+ cycling. This requirement, to-date, has mandated their application via gas phase deposition methods that include a variety of sputtering methods (e.g., magnetron), chemical vapor deposition (CVD), and atomic layer deposition (ALD). Unfortunately, these methods all require specialized apparatuses for controlling deposition atmospheres, deposition rates, film properties, and control of coating uniformity. As such, they represent an expensive and not easily scaled step in the fabrication of all solid-state batteries for large-scale commercial applications.
In contrast, polymeric ceramic precursor systems that are meltable or soluble offer a facile, low cost alternative to thin ceramic films. Polymer precursor methods of processing ceramics have been the subject of multiple reviews. However, this approach has not been applied to the synthesis of, as non-limiting examples, thin films of LiPON, LiAlOx,LiZnOx, M1M2PmHnOxNySz, for coatings and/or interfaces for battery applications.
A further advantage gained from using polymer precursors is that, because they can be applied in a liquid format, the precursors can also be used to coat particles to be used in forming and/or processing anode and cathode components; thereby serving as a non-fugitive binder during processing to dense or almost dense components. Alternately, these same precursors can be used to infiltrate porous green or intermediately sintered bodies, including electrolytes, anodes and cathodes, to both strengthen the component and/or to introduce continuous cation conducting phases within an initially porous ceramic such that they can act as a second ion conducting phase while also introducing additional, useful mechanical properties.
Finally, the processing of all solid-state batteries has inherent assembly problems. Processing methods can include sintering anode, cathode and electrolyte thin films in one step starting from green ceramic powder-filled polymer thin films that are themselves assembled and thereafter compressed or thermally compressed, followed by binder burnout and co-sintering all the green layers together at one time. Several problems arise from this approach: (1) each layer does not need the same processing conditions to reach full density with optimal properties, e.g., each layer will not sinter correctly under the harshest conditions needed to optimize the performance of the most difficult to sinter layer; (2) on heating, components (ions) in one layer may diffuse into other layers, changing both the phases, chemistries, electrochemistries and even mechanical properties in an undesired fashion; and (3) binder burnout in an intermediate treatment may lead to pores or other undesired defects (e.g., chemical reactions) in other layers such that optimization of all global properties is prevented.
Consequently, under some circumstances, the assembly of all solid-state batteries may best be conducted by forming individual layers first and then assembling them, which must involve uniform mating of surfaces. The problem therein is that the surface roughness (or smoothness) is not the same for each thin film needed to achieve intimate and/or uniform mating between two, or even three or more, components. One solution to this problem is to formulate a coating that can be a liquid or a meltable or malleable solid, such that uniform mating between two surfaces in question is possible. It is advantageous when, on heating such a coating, it not only transforms into an ion conducting interface, but it also acts to uniformly bond one surface to the other. Different surfaces may require different coatings, and as such, first coatings may be overlaid with second precursor coatings to ensure wetting of all components. It is further advantageous if the precursor coating system can be transformed into a ceramic (glass) interface at temperatures below those needed to sinter the original films, such that minimal chemical reactions take place unless desirable. For example, the precursor may serve as an “adhesive or bonding” interface that also penetrates to some extent a porous substrate to extend, on conversion to ceramic or glass, the conducting layer some distance into the substrate while also improving mechanical properties in the substrate and between bonded components.
Accordingly, polymeric precursors that address the foregoing problems associated with conventional precursors, that can be used to generate thin film, ceramic coatings of interface systems; as coatings on polymeric separators; and/or as composites with other polymers, e.g., polyethers, are desired.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
In various aspects, the current technology provides a method of synthesizing a precursor for making a polymer, glass or ceramic material. The method includes reacting OPCl3 with NH3 or MNH2, where M is Li, Na, K, Mg, Ca, Ba, or combinations thereof, to form O═P(NH2)3; and either: i. reacting the O═P(NH2)3 with M1NH2, where M1 is Li, Na, K, Mg, Ca, Ba, or combinations thereof, to form the precursor; or ii. heating the O═P(NH2)3 to form a branched or cyclomeric compound; and reacting the branched or cyclomeric compound with M1NH2, where M1 is Li, Na, K, Mg, Ca, Ba, or combinations thereof, to form the precursor.
The precursor is an oligomer or a polymer.
In one aspect, the reacting the OPCl3 with the NH3 or MNH2 is performed in a polar, aprotic solvent at a temperature of greater than or equal to about −50° C. to less than or equal to about 200° C.
In one aspect, the method includes i. and the reacting the O═P(NH2)3 with the M1NH2 is performed at a temperature of greater than or equal to about −50° C. to less than or equal to about 200° C. to from the precursor as the oligomer.
In one aspect, the method further includes heating the oligomer to a temperature greater than or equal to about 40° C. to less than or equal to about 300° C. to increase the molecular weight of the oligomer.
In one aspect, the method comprises i. and the reacting the O═P(NH2)3 with the M1NH2 is performed at a temperature of greater than about 20° C. to less than or equal to about 500° C. to from the precursor as the polymer.
In one aspect, the method further includes heating the polymer to a temperature greater than or equal to about 50° C. to less than or equal to about 400° C. to increase the ceramic yield of the polymer.
In one aspect, the method includes i. and further includes heating the precursor to a temperature of greater than or equal to about ambient temperature to less than or equal to about 1000° C. to form the glass or ceramic material.
In one aspect, the method further includes, prior to the heating, applying the oligomeric or polymeric precursor to at least a portion of a surface of a battery component selected from the group consisting of a cathode, an anode, a solid electrolyte, and combinations thereof, wherein the applying is performed by a process selected from the group consisting of doctor blading, spreading, brushing, spin casting, pouring, pipetting, printing, spray coating, dip coating, and combinations thereof.
In one aspect, the method includes ii. and the reacting is performed at a temperature of greater than or equal to about 30° C. to less than or equal to about 150° C.
In one aspect, the method includes ii. and is performed on a surface of, and optionally in pores of, a solid-state battery component selected from the group consisting of a cathode, an anode, a solid electrode, and combinations thereof.
In one aspect, the precursor has the formula M1aM2bPmHnNxOySz, where M1 is Li, Na, K, Mg, Ca, Ba, or combinations thereof; M2 is Al, S, Se, C, Si, Ge, Sn, Zn, or combinations thereof; 1≤a≤10; 0≤b≤10; 0≤m≤50; and 0≤n≤60; 0≤x≤50; 0≤y≤20; and 0≤z≤20.
In one aspect, the precursor is PON, LixPON, NaxPON, SiPON, LixSiPON, NaxSiPON, LiNaSiPON, or MgSiPON, where x is 1, 1.5, 3, or 6.
In one aspect, the method further includes combining the precursor with at least one of an electrode active material, with a separator material, or with a solid-state electrolyte material to generate at least one of a composite electrode material, a composite separator material, or a composite solid-state electrolyte material.
In one aspect, the method further includes adding the precursor to a solution including an ion-conducting polymer and a solvent to form a polymer-precursor solution; casting the polymer-precursor solution on a plate; and removing the solvent from the polymer-precursor solution to form an ion-conducting polymer-precursor composite material.
In one aspect, the ion-conducting polymer is polyethylene oxide (PEO), polypropylene oxide (PPO), an ion-conducting carboxylate polymer, copolymers thereof, or mixtures thereof.
In one aspect, the solvent is acetonitrile.
In one aspect, the precursor is PON, LixPON, NaxPON, SiPON, LixSiPON, NaxSiPON, LiNaSiPON, or MgSiPON, where x is 1, 1.5, 3, or 6.
In one aspect, the method further includes incorporating the ion-conducting polymer-precursor composite material into a solid-state battery as a solid composite electrolyte.
The current technology also provides the oligomeric or the polymeric precursor made by the above method.
The current technology yet also provides a method of synthesizing precursor for making a polymer, glass or ceramic material. The method includes reacting OPCl3 with (Me3X)2NH, where Me is methyl and X is Si, Ge, Sn, or combinations thereof, to form O═P(NHSiMe3)3; and reacting the O═P(NHSiMe3)3 with M1NH2, where M1 is Li, Na, K, Mg, Ca, Ba, or combinations thereof, to form the precursor. Then precursor is an oligomer or a polymer.
In one aspect, the reacting the OPCl3 with (Me3X)2NH is performed at a temperature of greater than or equal to about 20° C. to less than or equal to about 120° C. for a time of greater than or equal to about 2 minutes to less than or equal to about 10 hours.
In one aspect, the reacting the OPCl3 with the (Me3X)2NH is performed in a polar aprotic solvent.
In one aspect, the reacting the O═P(NHSiMe3)3 with the M1NH2 is performed at a temperature of greater than or equal to about −50° C. to less than or equal to about 200° C. to form the precursor as the oligomer.
In one aspect, the method further includes heating the oligomer to a temperature greater than or equal to about 40° C. to less than or equal to about 300° C. to d reacting the O═P(NHSiMe3)3 with M1NH2 is performed at a temperature of greater than about 20° C. to less than or equal to about 500° C. to from the precursor as the polymer.
In one aspect, the method further includes heating the polymer to a temperature greater than or equal to about 50° C. to less than or equal to about 400° C. to increase the ceramic yield of the polymer.
In one aspect, the method further includes reacting the precursor with at least one of Y(OR)n, Y(O2CR′)n, Y(NO3)n, and YCln, wherein Y is Al or Zn, n is 3 when Y is Al, n is 2 when Y is Zn, and R and R′ are independently a saturated C1-C5 alkyl that is branched or unbranched, and substituted or unsubstituted.
In one aspect, the method further includes reacting the oligomeric or polymeric precursor with at least one of Li2S or Li2Se.
In one aspect, the method further includes heating the precursor at a temperature of greater than or equal to about ambient temperature to less than or equal to about 1000° C. to form the glass or ceramic material.
In one aspect, the method further includes, prior to the heating, applying the precursor to at least a portion of a surface of a battery component selected from the group consisting of a cathode, an anode, a solid electrode, and combinations thereof, wherein the applying is performed by a process selected from the group consisting of doctor blading, spreading, brushing, spin casting, pouring, pipetting, printing, spray coating, dip coating, and combinations thereof, and wherein, after the heating, the glass or ceramic material is formed as a coating on at least a portion of the battery component.
In one aspect, the method further includes, prior to the heating, dipping a battery component selected from the group consisting of a cathode, an anode, a solid electrode, and combinations thereof into a solution comprising the oligomeric or polymeric precursor, wherein after the heating, the glass or ceramic material is formed as a coating that surrounds the battery component.
In one aspect, the method further includes combining the precursor with at least one of an electrode active material, with a separator material, or with a solid-state electrolyte material to generate at least one of a composite electrode material, a composite separator material, or a composite solid-state electrolyte material.
In one aspect, the precursor has the formula M1aM2bPmHnNxOySz, where M1 is Li, Na, K, Mg, Ca, Ba, or combinations thereof; M2 is Al, S, Se, C, Si, Ge, Sn, Zn, or combinations thereof; 1≤a≤10; 0≤b≤10; 0≤m≤50; and 0≤n≤60; 0≤x≤50; 0≤y≤20; and 0≤z≤20.
The current technology provides an oligomeric or polymeric precursor made according to the above method.
In various aspects, the current technology yet also provides a method of synthesizing a precursor for making a polymer, glass or ceramic material. The method includes reacting Cl6N3P3 with NH(SiMe3)2 to form a SiPHN as the precursor, wherein the precursor is an oligomer or a polymer.
In one aspect, the reacting is performed at a temperature of greater than or equal to about −50° C. to less than or equal to about 200° C. to form the precursor as the oligomer.
In one aspect, the method further includes heating the oligomer to a temperature greater than or equal to about 40° C. to less than or equal to about 300° C. to increase the molecular weight of the oligomer.
In one aspect, the reacting is performed at a temperature of greater than about 20° C. to less than or equal to about 500° C. to from the precursor as the polymer.
In one aspect, the method further includes heating the polymer to a temperature greater than or equal to about 50° C. to less than or equal to about 400° C. to increase the ceramic yield of the polymer.
In one aspect, a battery component including the precursor is provided.
In one aspect, the method further includes reacting the precursor with MNH2, where M is Li, Na, K, Mg, Ca, Ba, or combinations thereof, to form a MSiPHN precursor, wherein the MSiPHN precursor is an oligomer or a polymer.
In one aspect, the reacting the precursor with MNH2 is performed at a temperature of greater than or equal to about −50° C. to less than or equal to about 200° C. to form the MSiPHN precursor as the oligomer.
In one aspect, the method further includes heating the MSiPHN precursor oligomer to a temperature greater than or equal to about 40° C. to less than or equal to about 300° C. to increase the molecular weight of the MSiPHN precursor oligomer.
In one aspect, the reacting the precursor with MNH2 is performed at a temperature of greater than about 20° C. to less than or equal to about 500° C. to from the MSiPHN precursor as the polymer.
In one aspect, the method further includes heating the MSiPHN precursor polymer to a temperature greater than or equal to about 50° C. to less than or equal to about 400° C. to increase the ceramic yield of the MSiPHN precursor polymer.
In one aspect, a battery component including the MSiPHN precursor is provided.
In one aspect, the method further includes heating the MSiPHN precursor to a temperature of greater than or equal to about ambient temperature to less than or equal to about 1000° C. to form the glass or ceramic material.
In one aspect, a battery component including the polymer, glass, or ceramic material is provided.
The current technology yet further provides a precursor having the formula M1aM2bPmHnNxOySz, where M1 is Li, Na, K, Mg, Ca, Ba, or combinations thereof; M2 is Al, S, Se, C, Si, Ge, Sn, Zn, or combinations thereof; 1≤a≤10; 0≤b≤10; 0≤m≤5a; and 0≤n≤60; 0≤x≤5a; 0≤y≤20; and 0≤z≤20, wherein the precursor is an oligomer, or a polymer.
In one aspect, the precursor is in the form of a coating on a battery component selected from the group consisting of a cathode, an anode, a separator, a solid electrolyte and combinations thereof.
In one aspect, the precursor is combined with a cathode active material.
In one aspect, the precursor is combined with an anode active material.
In one aspect, the precursor is combined with an anode separator material.
In one aspect, the precursor is combined with a solid electrolyte.
In one aspect, the precursor is combined with an ion-conducting polymer as an ion-conducting polymer-precursor composite material.
In one aspect, the ion-conducting polymer is polyethylene oxide (PEO), polypropylene oxide (PPO), an ion-conducting carboxylate polymer, copolymers thereof, or mixtures thereof.
In one aspect, a solid state battery including a polymer, glass, or ceramic material formed from the precursor is provided.
In one aspect, a polymer, glass, or ceramic material formed from heating the precursor is provided.
In one aspect, the precursor is made by any method provided herein.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific compositions, components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, elements, compositions, steps, integers, operations, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Although the open-ended term “comprising,” is to be understood as a non-restrictive term used to describe and claim various embodiments set forth herein, in certain aspects, the term may alternatively be understood to instead be a more limiting and restrictive term, such as “consisting of” or “consisting essentially of” Thus, for any given embodiment reciting compositions, materials, components, elements, features, integers, operations, and/or process steps, the present disclosure also specifically includes embodiments consisting of, or consisting essentially of, such recited compositions, materials, components, elements, features, integers, operations, and/or process steps. In the case of “consisting of,” the alternative embodiment excludes any additional compositions, materials, components, elements, features, integers, operations, and/or process steps, while in the case of “consisting essentially of” any additional compositions, materials, components, elements, features, integers, operations, and/or process steps that materially affect the basic and novel characteristics are excluded from such an embodiment, but any compositions, materials, components, elements, features, integers, operations, and/or process steps that do not materially affect the basic and novel characteristics can be included in the embodiment.
Any method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed, unless otherwise indicated.
When a component, element, or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other component, element, or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Spatially or temporally relative terms, such as “before,” “after,” “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially or temporally relative terms may be intended to encompass different orientations of the device or system in use or operation in addition to the orientation depicted in the figures.
Throughout this disclosure, the numerical values represent approximate measures or limits to ranges to encompass minor deviations from the given values and embodiments having about the value mentioned as well as those having exactly the value mentioned. All numerical values of parameters (e.g., of quantities or conditions) in this specification, including the appended claims, are to be understood as being modified in all instances by the term “about” whether or not “about” actually appears before the numerical value. “About” indicates that the stated numerical value allows some slight imprecision (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein indicates at least variations that may arise from ordinary methods of measuring and using such parameters.
In addition, disclosure of ranges includes disclosure of all values and further divided ranges within the entire range, including endpoints and sub-ranges given for the ranges. As referred to herein, ranges are, unless specified otherwise, inclusive of endpoints and include disclosure of all distinct values and further divided ranges within the entire range. Thus, for example, a range of “from A to B” or “from about A to about B” is inclusive of A and of B.
Example embodiments will now be described more fully with reference to the accompanying drawings.
The current technology provides polymer precursors that can be applied as overcoats to process thin film, ceramic coatings of the respective interface systems. The polymer precursors themselves, or when mixed with other ion-conducting polymers, provide ion-conducting properties that were not anticipated during their formulation as ceramic precursors.
More particularly, the current technology provides a pathway to coatings that are similar to gas phase-deposited LiPON, but that utilize solution coating of ceramic precursors. The pathway includes the synthesis of, for example, O═P(NH2)3 from OPCl3 followed by lithiation by an Li source, such as LiNH2 as a non-limiting example. As an alternate method, OPCl3 is reacted with (Me3Si)2NH to generate Me3SiCl and O═P(NHSiMe3)3-x[NH]x which can be lithiated again by LiNH2. In yet another exemplary method, the cyclomer [Cl2P═N]3 reacts with (Me3Si)2NH to generate Me3SiCl and [P═N](NHSiMe3)33-x[NH]x which can be lithiated by LiNH2 or by another source of Li.
Accordingly, the current technology provides systems that permit simple coating from solutions or from solid polymer films. These polymers have excellent Li+ conductivities alone at ambient temperature and as mixtures with other ion conducting polymers. Upon heating to various temperatures less than 1000° C., polymer precursors, which are generally oligomers, will transform to PON, LiPON, SiPON, LiSiPON, SiPHN, LiSiPHN, or other materials with various compositions. Intermediates of these materials are characterized during heating in air or nitrogen by FTIR, TGA, and XRD. Surprisingly, coatings made on a variety of substrates with or without heating show Li+ conductivities several orders of magnitude higher (10−s vs 10−6 S/cm) than those expected from gas phase deposited materials at thicknesses of greater than or equal to about 1 μm and less than or equal to about 50 μm or greater than or equal to about 1 μm and less than or equal to about 20 μm.
The current technology provides methods of synthesizing compounds, oligomers or polymers of the formula M1aM2bPmHnOxNySz, where M1 is Li, Na, K, Mg, Ca, or Ba or combinations thereof, and M2 is S, Se, C, Si, Ge, Sn, Zn, or combinations thereof thereof. M1 is bonded to O, N, P or can bridge between two forms, such as M1O—P═N or O═P-NM1. The amount of M1 is 1≤a≤10 mol %. The amount of M2 can generally be from 0-10 times, preferably 1-5 times, with respect to the O, P, N, S or Se amounts, and is 1≤b≤10 mol %.content, n, x, y, and z are satisfy the following: 0≤m≤5a; and 0≤n≤60, 0≤x≤5a; 0≤y≤20a; 0≤z≤20a.
Oligomers or polymers having the above formula can be volatilized, dissolved and coated, melted and coated, or pressed onto or into substrates to generate polymers ceramic or glass powders, porous thin films, dense thin films, continuous interpenetrating second or third phases. Upon heating to a temperature of greater than or equal to about 100° C. to less than or equal to about 400° C. to the oligomers or polymers are formed. Upon heating to a temperature of greater than or equal to about 400° C. to less than or equal to about 1500° C. in a controlled atmosphere, the oligomers or polymers transform into, e.g., a lithium ion conducting, a sodium ion conducting, or a magnesium ion conducting, ceramic or glass coating having a thickness of greater than or equal to about 5 nm to less than or equal to about 20 μm. The coating imparts an interface to the coated substrate or powder, allowing it to be mated to another component and/or to fills pores in the substrate in order to provide semi- or continuous ion conducting sections and/or extends to the surface of a porous substrate. The coated substrate can also be used to cause one semi-flat surface to adhere strongly to another semi-flat surface, to mechanically and electrochemically bond one to the other, and to permit rapid ion diffusion across the resulting interface and/or through the substrate matrix, and/or coated particles, and/or cause particles to sinter together faster and at lower temperature to impart mechanical strength and improved electrochemical performance after heating to the temperatures of greater than or equal to about 400° C. to less than or equal to about 1500° C. in atmospheres of nitrogen, argon, hydrogen, and mixtures thereof depending on the target properties. Heating in air or oxygen is also useful for some formulations.
The current technology provides a method of synthesizing precursors to phosphorous oxynitrides, herein termed “PON”, with variable ratios of phosphorous to oxygen to nitrogen that may later be lithiated, sodiated or modified with magnesium. The PONs can be dissolved, melted or pressed to form thin films having a thickness of greater than or equal to about 5 nm to less than or equal to about 20 μm and then either the solvent is removed or the PONs are thermally converted to lithium, sodium, magnesium or mixed metal ion conductors on substrates that are powders of cathode, anode or electrolyte materials before or after processing such powders to selected forms, such as porous or dense thin films and or composites consisting of mixtures of cathode and electrically conducting materials such as carbon in any form, and/or forming thin films on preformed porous or dense films and also used to promote sintering at lower temperatures than without coatings and that coincidentally provide improved mechanical and electrochemical properties.
The current technology also provides a method of synthesizing precursors to silicon modified phosphorous oxynitrides, herein termed “SiPON”, with variable ratios of silicon to phosphorous to oxygen to nitrogen that may be later lithiated, sodiated or modified with magnesium and that can be dissolved, melted or pressed to form thin films having a thickness of greater than or equal to about 5 nm to less than or equal to about 20 μm and then thermally converted to lithium, sodium, magnesium or mixed metal ion conductors on substrates that are powders of cathode, anode or electrolyte materials before or after processing such powders to selected forms such as porous or dense thin films and or composites consisting of mixtures of cathode and electrically conducting materials such as carbon in any form and or forming thin films on preformed porous or dense films and also used to promote sintering at lower temperatures than without coatings and that coincidentally provide improved mechanical and electrochemical properties.
The current technology also provides a method of synthesizing precursors to sodium and silicon modified phosphorous oxynitrides, herein termed “NaSiPON”, with variable ratios of sodium and silicon to phosphorous to oxygen to nitrogen that may be later lithiated or modified with magnesium and that can be dissolved, melted or pressed to form thin films having a thickness of greater than or equal to about 5 nm to less than or equal to about 20 μm and then thermally converted to lithium, sodium, magnesium or mixed metal ion conductors on substrates that are powders of cathode, anode or electrolyte materials before or after processing such powders to selected forms such as porous or dense thin films and or composites consisting of mixtures of cathode and electrically conducting materials such as carbon in any form and or forming thin films on preformed porous or dense films and also used to promote sintering at lower temperatures than without coatings and that coincidentally provide improved mechanical and electrochemical properties.
The current technology also provides a method of synthesizing precursors to magnesium and silicon modified phosphorous oxynitrides, herein termed “MgSiPON”, with variable ratios of magnesium and silicon to phosphorous to oxygen to nitrogen that may be later lithiated or sodiated and that can be dissolved, melted or pressed to form thin films having a thickness of greater than or equal to about 5 nm to less than or equal to about 20 μm and then thermally converted to lithium, sodium, magnesium or mixed metal ion conductors on substrates that are powders of cathode, anode or electrolyte materials before or after processing such powders to selected forms such as porous or dense thin films and or composites consisting of mixtures of cathode and electrically conducting materials such as carbon in any form and or forming thin films on preformed porous or dense films and also used to promote sintering at lower temperatures than without coatings and that coincidentally provide improved mechanical and electrochemical properties.
In various embodiments, the methods include the following steps.
In various embodiments, the oligomers or polymers have the exemplary structures shown in
In various embodiments, the oligomeric or polymeric precursor infiltrates a porous substrate, provides reinforcement, i.e., increased strength, and provides an ion-conducting pathway by forming electrolyte pathways within a substrate as well as coating the surface, as shown in
Accordingly, the current technology provides a method of synthesizing a polymer or ceramic material precursor. The method includes reacting a compound according to one of the following pathways. The compound satisfies the formula PxOyNzXmHnCo, where 1≤x≤20, 1≤x≤10, 1≤x≤5; 0≤y≤20, 0≤y≤10, 0≤y≤5; 1≤z≤20, 1≤z≤10, 1≤z≤5; X is Cl, Br, I, CN or mixtures thereof; 1≤m≤20, 1≤m≤15, 1≤m≤10; 0≤n≤20, 0≤n≤10, 0≤n≤5; and 0≤o≤20, 0≤o≤10, 0≤o≤5. The compound is soluble in aprotic solvents.
In a first pathway, X is a halogen. The compound is reacted with NH3 to form NH4X (a byproduct removed by filtration) and the intermediate PxOyNz+mHn+(m−1 or m−2)Co. The intermediate is warmed at a temperature of greater than or equal to about 10° C. to less than or equal to about 150° C. in solution or in a solid phase to eliminate NH3 and form an oligomeric, or polymeric precursor, which remains soluble in aprotic solvents and meltable.
In another pathway, the compound is reacted with MNH2 or M(NH2)2 or mixtures thereof, where M=Li, Na, K, Ca, Mg, or Ba to form the intermediate PxOyNz+mHn+(m−1 or m−2)Co coincident with MX1(2). The intermediate is warmed at a temperature of greater than or equal to about 10° C. to less than or equal to about 150° C. in solution or in a solid phase to eliminate NH3 to an oligomeric, or polymeric precursor, which remains soluble in aprotic solvents and meltable.
In some variations, excess MNH2 or M(NH2)2 or mixtures thereof are used to form the second intermediate M1M2PxOyNzXmHnCo. The second intermediate is warmed at a temperature of greater than or equal to about 10° C. to less than or equal to about 150° C. in solution or in a solid phase to eliminate NH3 to an oligomeric, or polymeric precursor, which remains soluble in aprotic solvents and meltable.
In another pathway, the compound is reacted with silyl compounds as exemplified by (R3Si)2NH (where R is C1-C8 alkyl or H) to generate volatile R3SiX, which can be evaporated from solution before or after recovery of the intermediate (R3Si)mPxOyNz+mHn+(m−1 or m−2)Co. The intermediate is warmed at a temperature of greater than or equal to about 10° C. to less than or equal to about 150° C. in solution or in a solid phase to eliminate NH3 (or R3SiNH2) to an oligomeric, or polymeric precursor, which remains soluble in aprotic solvents and meltable.
Alternately, the intermediate is treated with MNH2 or M(NH2)2 or mixtures thereof to produce the intermediate M1M2(R3Si)mPxOyNz+mHn+(m−2,3,−6)Co (where R is C1-C8 alkyl or H). This intermediate is heated gently at a temperature of greater than or equal to about 10° C. to less than or equal to about 150° C. to produce a higher molecular weight aprotic-solvent soluble and meltable precursor.
The current technology provides another method of synthesizing a precursor for making a polymeric, glass, or ceramic material. The method comprises reacting OPCl3 with NH3 or MNH2, where M is Li, Na, K, Mg, Ca, Ba, or combinations thereof, to form O═P(NH2)3. The reacting the OPCl3 with MNH2 is performed in a polar, aprotic solvent at a temperature of greater than or equal to about −50° C. to less than or equal to about 200° C., greater than or equal to about 0° C. to less than or equal to about 150° C., or greater than or equal to about 20° C. to less than or equal to about 70° C., thus forming a reaction mixture. Non-limiting examples of polar, aprotic solvents include tetrahydrofuran (THF), dimethoxyethane (glyme), bis(2-methoxyethyl) ether (diglyme), acetone, N—N-dimethylformamide (DMF), acetonitrile (MeCN), dimethyl sulfoxide (DMSO), and combinations thereof.
The method then comprises reacting the O═P(NH2)3 with M1NH2, where M1 is Li, Na, K, Mg, Ca, Ba, or combinations thereof, to form the precursor as an oligomer or a polymer. The reacting comprises adding the M1NH2 to the reaction mixture. To form the oligomer, the reacting the O═P(NH2)3 with the M1NH2, is performed at a temperature of greater than or equal to about −50° C. to less than or equal to about 200° C., greater than or equal to about 0° C. to less than or equal to about 150° C., or greater than or equal to about 25° C. to less than or equal to about 100° C. To form the polymer, the reacting the O═P(NH2)3 with the M1NH2 is performed at a temperature of greater than or equal to about 20° C. to less than or equal to about 500° C., greater than or equal to about 50° C. to less than or equal to about 450° C., or greater than or equal to about 75° C. to less than or equal to about 400° C. In some embodiments, the O═P(NH2)3 is heated to form a branched or cyclomeric compound and then reacted with the M1NH2 as discussed above.
In some embodiments the method further comprises increasing the molecular weight of the oligomeric precursor by heating the oligomeric precursor to a temperature of greater than or equal to about 40° C. to less than or equal to about 300° C., greater than or equal to about 50° C. to less than or equal to about 250° C., or greater than or equal to about 75° C. to less than or equal to about 200° C. In other embodiments, the method further comprises increasing a ceramic yield of the polymeric precursor by heating the polymeric precursor to a temperature of greater than or equal to about 50° C. to less than or equal to about 400° C., greater than or equal to about 75° C. to less than or equal to about 350° C., or greater than or equal to about 100° C. to less than or equal to about 300° C.
The precursor itself can be used in a variety of embodiments. As non-limiting examples, the precursor can be used: (1) as a solid-state electrolyte for a solid-state battery that cycles lithium or sodium ions; (2) to generate composite electrolyte films, e.g., ion-conducting polymer-precursor composite material, wherein the ion-conducting polymer is polyethylene oxide (PEO), polypropylene oxide (PPO), an ion-conducting carboxylate polymer, copolymers thereof, or mixtures thereof; (3) as a film coating on a polymer separator, including for use in a symmetric cell; (4) to generate composite films on a substrate that is not a separator, including for use in a symmetric cell, e.g., PEO/precursor composite films substrates; (5) as a binder in an anode active material and/or in a cathode active material; and (6) as a ceramic-forming adhesive.
The oligomeric or polymeric precursor can optionally be transformed into the polymer, glass or ceramic material by heating the oligomeric or polymeric precursor to a temperature of greater than or equal to about ambient temperature to less than or equal to about 1500° C., greater than or equal to about ambient temperature to less than or equal to about 1000° C., or greater than or equal to about 100° C. to less than or equal to about 1000° C. to form the polymer, glass, or ceramic material. As used herein, a “glass” is a non-crystalline (amorphous)inorganic material that has glass transition and a “ceramic” is a crystalline, semi-crystalline, or non-crystalline inorganic material that does not have a glass transition.
The polymer, glass, or ceramic precursor material can be used, as non-limiting examples, as a bonding agent between components of a solid-state electrode, to fill pores in a solid-state battery component, as a polymer applied to a ceramic substrate, or as a sintering aid. In various embodiments, the method further comprises applying the oligomeric or polymeric precursor to at least a portion of a surface, and optionally within pores, of a battery component selected from the group consisting of a cathode, an anode, a solid electrolyte, and combinations thereof, and then heating to form the ceramic material as described above. A second solid-state battery component can be disposed on top of the oligomeric or polymeric precursor before the heating in order to generate a ceramic bond or interface between the components after the heating. The applying can be performed by any method known in the art, such as by a process selected from the group consisting of doctor blading, spreading, brushing, spin casting, pouring, pipetting, printing, spray coating, dip coating, and combinations thereof as non-limiting examples. In some embodiments, the solid-state battery component is dip-coated into the oligomeric or polymeric precursor, and then the heating is performed to generate a solid coating that surrounds the solid-state battery component and fills pores within the component when present. The ceramic material can be substantially free of pinholes, i.e., holes having a diameter of greater than or equal to about 5 nm to less than or equal to about 20 nm. By “substantially free” it is meant that less than about 5%, less than about 2.5%, less than 1%, or less than 0.5% of the ceramic material comprises pinholes. The glass or ceramic material is conductive to ions, such as Li, Na, Mg, or Si ions. In some embodiments, the glass or ceramic material includes pinholes, which can be filled with the same or different glass or ceramic material.
The current technology provides another method of synthesizing a precursor for making a polymer, glass, or ceramic material. The method comprises reacting OPCl3 with NH3 or MNH2, where M is Li, Na, K, Mg, Ca, Ba, or combinations thereof, to form O═P(NH2)3. The reacting the OPCl3 with MNH2 is performed in a polar, aprotic solvent at a temperature of greater than or equal to about −50° C. to less than or equal to about 200° C., greater than or equal to about 0° C. to less than or equal to about 150° C., or greater than or equal to about 20° C. to less than or equal to about 70° C.; thus forming a reaction mixture. Non-limiting examples of polar, aprotic solvents include tetrahydrofuran (THF), dimethoxyethane (glyme), bis(2-methoxyethyl) ether (diglyme), acetone, N—N-dimethylformamide (DMF), acetonitrile (MeCN), dimethyl sulfoxide (DMSO), and combinations thereof.
The method then comprises heating the O═P(NH2)3 to form a branched or cyclomeric compound and reacting the branched or cyclomeric compound with M1NH2, where M1 is Li, Na, K, Mg, Ca, Ba, or combinations thereof, to form the precursor. as an oligomer or a polymer. To form the oligomer, the reacting the O═P(NH2)3 with the M1NH2, is performed at a temperature of greater than or equal to about −50° C. to less than or equal to about 200° C., greater than or equal to about 0° C. to less than or equal to about 150° C., or greater than or equal to about 25° C. to less than or equal to about 100° C. To form the polymer, the reacting the O═P(NH2)3 with the M1NH2 is performed at a temperature of greater than or equal to about 20° C. to less than or equal to about 500° C., greater than or equal to about 50° C. to less than or equal to about 450° C., or greater than or equal to about 75° C. to less than or equal to about 400° C.
In some embodiments the method further comprises increasing the molecular weight of the oligomeric precursor by heating the oligomeric precursor to a temperature of greater than or equal to about 40° C. to less than or equal to about 300° C., greater than or equal to about 50° C. to less than or equal to about 250° C., or greater than or equal to about 75° C. to less than or equal to about 200° C. In other embodiments, the method further comprises increasing a ceramic yield of the polymeric precursor by heating the polymeric precursor to a temperature of greater than or equal to about 50° C. to less than or equal to about 400° C., greater than or equal to about 75° C. to less than or equal to about 350° C., or greater than or equal to about 100° C. to less than or equal to about 300° C.
The precursor itself can be used in a variety of embodiments. As non-limiting examples, the precursor can be used: (1) as a solid-state electrolyte for a solid-state battery that cycles lithium or sodium ions; (2) to generate composite electrolyte films, e.g., ion-conducting polymer-precursor composite material, wherein the ion-conducting polymer is polyethylene oxide (PEO), polypropylene oxide (PPO), an ion-conducting carboxylate polymer, copolymers thereof, or mixtures thereof; (3) as a film coating on a polymer separator, including for use in a symmetric cell; (4) to generate composite films on a substrate that is not a separator, including for use in a symmetric cell, e.g., PEO/precursor composite films substrates; (5) as a binder in an anode active material and/or in a cathode active material; and (6) as a ceramic-forming adhesive.
The oligomeric or polymeric precursor can optionally be transformed into the polymer glass or ceramic material by heating the oligomeric or polymeric precursor to a temperature of greater than or equal to about ambient temperature to less than or equal to about 1500° C., greater than or equal to about ambient temperature to less than or equal to about 1000° C., or greater than or equal to about 100° C. to less than or equal to about 1000° C. to form the polymer, glass, or ceramic material.
The glass or ceramic material can be used, as non-limiting examples, as a bonding agent between components of a solid-state electrode, to fill pores in a solid-state battery component, as a ceramic disposed on a ceramic substrate, or as a sintering aid. In various embodiments, the method further comprises applying the oligomeric or polymeric precursor to at least a portion of a surface, and optionally within pores, of a battery component selected from the group consisting of a cathode, an anode, a solid electrolyte, and combinations thereof, and then heating to form the ceramic material as described above. A second solid-state battery component can be disposed on top of the oligomeric or polymeric precursor before the heating in order to generate a ceramic bond or interface between the components after the heating. The applying can be performed by any method known in the art, such as by a process selected from the group consisting of doctor blading, spreading, brushing, spin casting, pouring, pipetting, printing, spray coating, dip coating, and combinations thereof as non-limiting examples. In some embodiments, the solid-state battery component is dip-coated into the oligomeric or polymeric precursor, and then the heating is performed to generate a solid coating that surrounds the solid-state battery component and fills pores within the component when present. The ceramic material can be substantially free of pinholes, i.e., holes having a diameter of greater than or equal to about 5 nm to less than or equal to about 20 nm. By “substantially free” it is meant that less than about 5%, less than about 2.5%, less than 1%, or less than 0.5% of the ceramic material comprises pinholes. The some embodiments, the glass or ceramic material includes pinholes, which can be filled with the same or different glass or ceramic material.
The current technology further provides another method of synthesizing a precursor for making a polymer, glass, or ceramic material. The method comprises reacting OPCl3 with (Me3X)2NH, where Me is methyl and X is Si, Ge, Sn, or combinations thereof, to form O═P(NHSiMe3)3. Although it is understood that other alkyl groups other than methyl can be used, the use of methyl is described herein. The reacting OPCl3 with (Me3X)2NH, is performed in a polar, aprotic solvent as described above; thus forming a reaction mixture, and at a temperature of greater than or equal to about −50° C. to less than or equal to about 200° C., greater than or equal to about −10° C. to less than or equal to about 150° C., greater than or equal to about 20° C. to less than or equal to about 120° C., or greater than or equal to about 40° C. to less than or equal to about 100° C. for a time of greater than or equal to about 2 minutes to less than or equal to about 10 hours, greater than or equal to about 30 minutes to less than or equal to about 8 hours, or greater than or equal to about 1 hour to less than or equal to about 6 hours.
The method then comprises adding M1NH2 to the reaction mixture and reacting the O═P(NHSiMe3)3 with the M1NH2, where M1 is Li, Na, K, Mg, Ca, Ba, or combinations thereof to form the precursor as an oligomer or a polymer. To form the oligomer, the reacting the O═P(NHSiMe3)3 with the M1NH2 is performed at a temperature of greater than or equal to about −50° C. to less than or equal to about 200° C., greater than or equal to about 0° C. to less than or equal to about 150° C., or greater than or equal to about 25° C. to less than or equal to about 100° C. To form the polymer, the reacting the O═P(NHSiMe3)3 with the M1NH2 is performed at a temperature of greater than or equal to about 20° C. to less than or equal to about 500° C., greater than or equal to about 50° C. to less than or equal to about 450° C., or greater than or equal to about 75° C. to less than or equal to about 400° C.
In some embodiments the method further comprises increasing the molecular weight of the oligomeric precursor by heating the oligomeric precursor to a temperature of greater than or equal to about 40° C. to less than or equal to about 300° C., greater than or equal to about 50° C. to less than or equal to about 250° C., or greater than or equal to about 75° C. to less than or equal to about 200° C. In other embodiments, the method further comprises increasing a ceramic yield of the polymeric precursor by heating the polymeric precursor to a temperature of greater than or equal to about 50° C. to less than or equal to about 400° C., greater than or equal to about 75° C. to less than or equal to about 350° C., or greater than or equal to about 100° C. to less than or equal to about 300° C.
In some embodiments, at least one of Al, Zn, S, or Se is introduced into the oligomeric or polymeric precursor. In order to introduce Al and/or Zn, the method comprises reacting the oligomeric or polymeric precursor with at least one of Y(OR)n, Y(O2CR′)n, Y(NO3)n, and YCln, wherein Y is Al or Zn, n is 3 when Y is Al, n is 2 when Y is Zn, and R and R′ are independently a saturated C1-C5 alkyl that is branched or unbranched, and substituted or unsubstituted, such as methyl or propyl as non-limiting examples. In order to introduce S and/or Se, the method comprises reacting the oligomeric or polymeric precursor with at least one of Li2S or Li2Se at a temperature of greater than or equal to about room temperature to less than or equal to about 80° C.
The precursor itself can be used in a variety of embodiments. As non-limiting examples, the precursor can be used: (1) as a solid-state electrolyte for a solid-state battery that cycles lithium or sodium ions; (2) to generate composite electrolyte films, e.g., ion-conducting polymer-precursor composite material, wherein the ion-conducting polymer is polyethylene oxide (PEO), polypropylene oxide (PPO), an ion-conducting carboxylate polymer, copolymers thereof, or mixtures thereof; (3) as a film coating on a polymer separator, including for use in a symmetric cell; (4) to generate composite films on a substrate that is not a separator, including for use in a symmetric cell, e.g., PEO/precursor composite films substrates; (5) as a binder in an anode active material and/or in a cathode active material; and (6) as a ceramic-forming adhesive.
The oligomeric or polymeric precursor can optionally be transformed into the polymer, glass, or ceramic material by heating the oligomeric or polymeric precursor to a temperature of greater than or equal to about ambient temperature to less than or equal to about 1500° C., greater than or equal to about ambient temperature to less than or equal to about 1000° C., or greater than or equal to about 100° C. to less than or equal to about 1000° C. to form the polymer, glass or ceramic material.
The ceramic material can be used, as non-limiting examples, as a bonding agent between components of a solid-state electrode, to fill pores in a solid-state battery component, as a ceramic disposed on a ceramic substrate, or as a sintering aid. In various embodiments, the method further comprises applying the oligomeric or polymeric precursor to at least a portion of a surface, and optionally within pores, of a battery component selected from the group consisting of a cathode, an anode, a solid electrolyte, and combinations thereof, and then heating to form the ceramic material as described above. A second solid-state battery component can be disposed on top of the oligomeric or polymeric precursor before the heating in order to generate a ceramic bond or interface between the components after the heating. The applying can be performed by any method known in the art, such as by a process selected from the group consisting of doctor blading, spreading, brushing, spin casting, pouring, pipetting, printing, spray coating, dip coating, and combinations thereof as non-limiting examples. In some embodiments, the solid-state battery component is dip-coated into the oligomeric or polymeric precursor, and then the heating is performed to generate a solid coating that surrounds the solid-state battery component and fills pores within the component when present. The ceramic material can be substantially free of pinholes, i.e., holes having a diameter of greater than or equal to about 5 nm to less than or equal to about 20 nm. By “substantially free” it is meant that less than about 5%, less than about 2.5%, less than 1%, or less than 0.5% of the ceramic material comprises pinholes. The ceramic material is conductive to ions, such as Li, Na, Mg, or Si ions. In some embodiments, the glass or ceramic material includes pinholes, which can be filled with the same or different glass or ceramic material.
The current technology yet further provides another method of synthesizing a precursor for making a polymer, glass, or ceramic material. The method comprises reacting Cl6N3P3 with NH(SiMe3)2 to form the precursor as either a SiPHN oligomer precursor or a SiPHN polymer precursor. To form the SiPHN oligomer precursor, the reacting the Cl6N3P3 with the NH(SiMe3)2 is performed at a temperature of greater than or equal to about −50° C. to less than or equal to about 200° C., greater than or equal to about 0° C. to less than or equal to about 150° C., or greater than or equal to about 25° C. to less than or equal to about 100° C. To form the SiPHN polymer precursor, the reacting the Cl6N3P3 with the NH(SiMe3)2 is performed at a temperature of greater than or equal to about 20° C. to less than or equal to about 500° C., greater than or equal to about 50° C. to less than or equal to about 450° C., or greater than or equal to about 75° C. to less than or equal to about 400° C.
In various embodiments, the method further includes reacting the SiPHN precursor with MNH2, where M is Li, Na, K, Mg, Ca, Ba, or combinations thereof to form a MSiPHN precursor as either a MSiPHN oligomer precursor or a MSiPHN polymer precursor. To form the MSiPHN oligomer precursor, the reacting the Cl6N3P3 with the NH(SiMe3)2 is performed at a temperature of greater than or equal to about −50° C. to less than or equal to about 200° C., greater than or equal to about 0° C. to less than or equal to about 150° C., or greater than or equal to about 25° C. to less than or equal to about 100° C. To form the MSiPHN polymer precursor, the reacting the Cl6N3P3 with the NH(SiMe3)2 is performed at a temperature of greater than or equal to about 20° C. to less than or equal to about 500° C., greater than or equal to about 50° C. to less than or equal to about 450° C., or greater than or equal to about 75° C. to less than or equal to about 400° C.
In some embodiments the method further comprises increasing the molecular weight of the SiPHN or MSiPHN oligomer precursor by heating the SiPHN or MSiPHN oligomer precursor to a temperature of greater than or equal to about 40° C. to less than or equal to about 300° C., greater than or equal to about 50° C. to less than or equal to about 250° C., or greater than or equal to about 75° C. to less than or equal to about 200° C. In other embodiments, the method further comprises increasing a ceramic yield of the SiPHN or MSiPHN polymer precursor by heating the SiPHN or MSiPHN polymeric precursor to a temperature of greater than or equal to about 50° C. to less than or equal to about 400° C., greater than or equal to about 75° C. to less than or equal to about 350° C., or greater than or equal to about 100° C. to less than or equal to about 300° C.
The SiPHN precursor or the MSiPHN precursor themselves can be used in a variety of embodiments. As non-limiting examples, the precursors can be used: (1) as a solid-state electrolyte for a solid-state battery that cycles lithium or sodium ions; (2) to generate composite electrolyte films, e.g., ion-conducting polymer-precursor composite material, wherein the ion-conducting polymer is polyethylene oxide (PEO), polypropylene oxide (PPO), an ion-conducting carboxylate polymer, copolymers thereof, or mixtures thereof; (3) as a film coating on a polymer separator, including for use in a symmetric cell; (4) to generate composite films on a substrate that is not a separator, including for use in a symmetric cell, e.g., PEO/precursor composite films substrates; (5) as a binder in an anode active material and/or in a cathode active material; and (6) as a ceramic-forming adhesive.
The SiPHN precursor or the MSiPHN precursor can optionally be transformed into the corresponding polymer glass or ceramic material by heating the SiPHN precursor or the MSiPHN precursor to a temperature of greater than or equal to about ambient temperature to less than or equal to about 1500° C., greater than or equal to about ambient temperature to less than or equal to about 1000° C., or greater than or equal to about 100° C. to less than or equal to about 1000° C. to form the polymer, glass, or ceramic material.
The glass or ceramic material can be used, as non-limiting examples, as a bonding agent between components of a solid-state electrode, to fill pores in a solid-state battery component, as a ceramic disposed on a ceramic substrate, or as a sintering aid. In various embodiments, the method further comprises applying the oligomeric or polymeric precursor to at least a portion of a surface, and optionally within pores, of a battery component selected from the group consisting of a cathode, an anode, a solid electrolyte, and combinations thereof, and then heating to form the ceramic material as described above. A second solid-state battery component can be disposed on top of the oligomeric or polymeric precursor before the heating in order to generate a ceramic bond or interface between the components after the heating. The applying can be performed by any method known in the art, such as by a process selected from the group consisting of doctor blading, spreading, brushing, spin casting, pouring, pipetting, printing, spray coating, dip coating, and combinations thereof as non-limiting examples. In some embodiments, the solid-state battery component is dip-coated into the oligomeric or polymeric precursor, and then the heating is performed to generate a solid coating that surrounds the solid-state battery component and fills pores within the component when present. The ceramic material can be substantially free of pinholes, i.e., holes having a diameter of greater than or equal to about 5 nm to less than or equal to about 20 nm. By “substantially free” it is meant that less than about 5%, less than about 2.5%, less than 1%, or less than 0.5% of the ceramic material comprises pinholes. The some embodiments, the glass or ceramic material includes pinholes, which can be filled with the same or different glass or ceramic material.
The current technology also provides a method of fabricating a solid-state battery that comprises applying any of the oligomeric or polymeric precursors described herein to a battery component, and heating the oligomeric or polymeric precursor to form a ceramic material. The battery component can be, for example, an anode, a cathode, a solid-state electrolyte, a separator, or a combination thereof. The polymeric precursors can be added to a battery component material prior to the heating in order to generate a composite battery component material or the polymeric precursors can be applied over the battery component in order to generate a coated battery component. Alternatively, as discussed above, in some embodiments the precursor is included in the battery component without heating and conversion into a ceramic material.
The current technology also provides an oligomeric or polymeric precursor made by any of the above methods.
The current technology also provides a ceramic material made from an oligomeric or polymeric precursor by any of the above methods
The current technology also provides a solid state battery comprising a ceramic material made by any of the above methods. The ceramic material is disposed on at least one of an anode, a cathode, a separator, or a solid-state electrolyte.
The current technology yet further provides a compound having the formula M1aM2bPmHnOxNySz where M1 is Li, Na, K, Mg, Ca, Ba, or combinations thereof; M2 is Al, S, Se, C, Si, Ge, Sn, Zn, or combinations thereof; 1≤a≤10; 0≤b≤10; 0≤m≤5a; and 0≤n≤60, 0≤x≤5a; 0≤y≤20a; 0≤z≤20a, wherein the compound is an oligomer, or polymer that is configured to form a coating, a bonding material, or an ion conducting pathway through a porous material. The compound is made according to any of the methods provided herein. The compound can optionally be heated as described above in order to be transformed into a ceramic material.
The current technology also provides a solid-state battery comprising a ceramic material formed from the compound having the formula M1aM2bNxOyPzHc.
Embodiments of the present technology are further illustrated through the following non-limiting examples.
In order to demonstrate the utility of making precursors according to the current technology, it is also important to have a set of substrates qualified to be used to test the efficacy of the coatings and processing conditions explored. To optimize ion conductivity in the resulting ceramized precursors, well-defined substrates are needed that offer: (1) no lithium or sodium ion conductivity; (2) minimal lithium or sodium ion conductivity; or (3) good lithium or sodium ion conductivity. The below approaches either use a polymer separator as a substrate or eliminate the need for a ceramic substrate.
To this end, a series of produced substrates are chosen that are typically 10-50 μm thick and fully or partially dense and meet the criteria just above. Thus, thin films of α-Al2O3, LiAlO2 of various densities, and LATSP (Li1.7Al0.3Ti1.7Si0.4P2.6O12) are coated. Substrates of these materials exhibit Li+ conductivities as shown in Table 1.
The first step in developing precursors is to realize, simple low cost, minimal step syntheses of precursor systems that are easily modified to allow exploration, and thereafter, control of both precursor properties and processing conditions necessary to generate optimal coating, binder and bonding systems. Thus, work to explore synthetic approaches to various precursors is described.
Precursor Syntheses.
Polymer Precursor Reactions for PON and LixPON.
Several approaches can be used for these precursors. Perhaps the simplest is ammonolysis of OPCl3 to produce the phosphoramide OP(NH2)3:
However, depending on the solvent used, byproduct NH4Cl is difficult to remove or interfere with purification. An alternative uses NaNH2 as follows:
The reason for using NaNH2 rather than LiNH2 is that LiCl is more soluble in polar solvents than NaCl and may not precipitate as easily, and thus, NaNH2 is preferable in some embodiments.
Thereafter, there are two options for producing LiPON precursors. The first is to promote oligomerization/polymerization following reactions shown as stepwise condensation reactions (in which “slight heat” refers to heating from greater than or equal to about −10° C. to less than or equal to about 100° C.):
As shown, only linear oligomers are formed. However, it is highly likely that both branched and cyclomeric products are produced coincidentally:
The volatile system offers a novel method for chemical vapor deposition. At this juncture, it is possible to now add Li as shown below:
As an alternative, it is preferred that this be done right after the first step. This may not be optimal, but it appears to be the easiest approach:
The Li content can be controlled by the degree of initial lithiation. Promoting a condensation reaction can also take place as described above. The condensation process is very likely to be much more complex than shown. However, one can use these intermediates as precursors to make LiPON thin films, binders or bonding agents by using traditional precursor processing techniques. In some instances, the intermediates will be liquids and in others, they will be meltable or soluble solids.
As demonstrated in the examples described below, it is possible to make Li1.5PON, Li3PON and Li6PON precursors simply by choosing the amount of LiNH2 to add. It is also possible to make a sodium equivalent by adding more NaNH2 to make a NaPON precursor, for example Na3PON. It is also possible to make a mixed ion precursor by adding both NaNH2 and LiNH2 in any possible ratio desired as demonstrated in the examples below.
Finally, a magnesium counterpart can be made by adding a magnesium amide such as Mg(NiPr2)2, which is used as an example and not meant to be limiting. Again, a mixed ion precursor can also be made by using any type of Na, Li or Mg compound that has the potential to either abstract a hydrogen from O═P(NH2)3 or oligomeric analogs replacing said hydrogen with that metal and any ratio of metals can be chosen to optimize ionic conductivity and other processing properties.
Polymer Precursors to LiSiPON.
The synthesis of silicon containing LiPON or LiSiPON has been previously reported. The following approach to precursors has not been used. In its simplest form, it takes advantage of the affinity of Si for Cl:
Another embodiment uses less than 2.5 (Me3Si)2NH:
At this stage, the above compound can be lithiated (or use sodium or magnesium):
and then heated, as suggested by the following which is not meant to be the only reaction pathway:
The resulting material's composition will depend on the original amount of LiNH2 [NaNH2 or Mg(NiPr)2] or other deprotonating metallating compound introduced, and the conductivity will be determined by this as well as processing conditions. Thus, Li1.5SiPON, Li3SiPON, Li6SiPON, Na3SiPON, and Mg1.5SiPON can be made as non-limiting exemplary M1M2PmHnOxNySz compounds.
SiPHN and LixSPHN systems
The use of a polymer that is solely based on phosphorus and nitrogen is explored. The scheme starts form the cyclomer [Cl2P═N]3 and replaces Cl with NH via a Si—Cl exchange process.
These examples demonstrate an approach for formulating systems for making processable polymers by using non-stoichiometric amounts of (Me3Si)2NH.
Experimental Methods.
Materials. Aluminum tri-sec-butoxide {Al[OCH(CH3)CH2CH3]3} is purchased from Chattem Chemicals (Chattanooga, Tenn.), and absolute ethanol from Decon Labs (King of Prussia, Pa.). Triethanolamine [N(CH2CH2OH)3], Polyacrylic acid [(C3H4O2)n, Mn 2000], Polyethylene glycol [H(OCH2CH2)nOH, Mn 3400], Methyl ethyl ketone [C2H5COCH3], Benzyl butyl phthalate {2-[CH3(CH2)3O2C] C6H4CO2CH2C6H5, 98%}, Lithium hydroxide monohydrate [LiOH·H2O] and Propionic acid [CH3CH2COOH] are purchased from Sigma-Aldrich (Milwaukee, Wis.). Polyvinyl butyral [(C8H14O2)n, B-98, Mn 40,000-70,000] is purchased from Butvar (Avon, Ohio). Tetraethoxysilane [Si(OC2H5)4], Triethyl phosphate [(C2H5O)3PO], Titanium isopropoxide [Ti(OiPr)4] is purchased from Fischer Scientific (Pittsburgh, Pa.).
Analytical Methods.
Thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) are performed on a SDT Q600 simultaneous TGA/DSC (TA instrument, Inc.). Samples (15-25 mg), hand pressed in a 3-mm dual action die, are placed in alumina pans and heated to 1000° C. at 10° C. min−1 under constant N2 flow (60 mL min−1).
Scanning electron microscopy (SEM). Micrographs of as-produced and sintered thin films are taken using JSM-IT300HR In Touch Scope SEM (JEOL USA, Inc.) For imaging purpose, thin films are fractured, and powders are used as is. SPI sputter coater (SPI Supplies, Inc.) is used to sputter coat all the samples with gold and palladium.
X-Ray diffraction (XRD). As-produced powders and sintered films are characterized using Rigaku Rotating Anode Goniometer (Rigaku Denki., LTD., Tokyo, Japan). For data collection, as-produced powders are prepared by placing ˜100 mg in XRD sample holders. Cu Kα (λ=1.54 Å) radiation operating at working voltage of 40 kV and current of 100 mA is used. Scans are continuous from 10 to 70° 2θ using a scan rate of 5 min−1 in 0.01 increments. The presence of crystallographic phases, and their wt. fraction is determined by using Jade program 2010 (Version 1.1.5 from Materials Data, Inc.).
FTIR Spectra analyses are run on Nicolet 6700 Series FTIR spectrometer (Thermo Fisher Scientific, Inc.) and are used to measure FTIR spectra. 1 wt. % of the samples are mixed with KBr (International Crystal Laboratories); the mixtures are ground rigorously with an alumina mortal pestle; and the dilute samples are packed in the sample holder to be analyzed. Prior to data acquisition in the range of 4000-400 cm−1, the sample chamber is purged with N2.
GPC analyses is done on a Waters 440 system equipped with Waters Styragel columns (7.8×300, HT 0.5, 2, 3, 4) with RI detection using an Optilab DSP interferometric refractometer and THF as solvent. The system is calibrated using polystyrene standards. Analyses are performed using Empower 3 Chromatography Data Software (Waters, Corp., Milford, Mass.).
MALDI-TOF is done on Bruker AutoFlex Speed using poly(ethylene glycol) as a calibration standard, trihydroxyanthracene as the matrix and AgNO3 as the ion source. Samples are prepared by mixing solutions of 5 parts matrix (10 mg mL−1 in THF), 5 parts sample (1 mg mL−1 in THF), and optionally 1 part AgNO3 (1.0 mg mL−1 in THF) and blotting the mixture on the target plate.
AC Impedance data is collected with broadband dielectric spectrometer (Biologics) in a frequency range of 7 MHz to 1 Hz at −35 to 80° C. in increments of 10° C. Concentric gold electrodes, 3 mm in diameter, are deposited using a SPI sputter coater on both surfaces of the films using a deposition mask. “EIS spectrum analyser” software is used for extracting total resistance. Equivalent circuit consisting of (RtotalQtotal)(Qelectrode) is used. R and Q denote resistance and constant phase element, respectively. SEM fracture surface images are taken to measure sample thicknesses.
Synthesis of PON from Phosphoramide.
In a 200 mL round bottom Schlenk flask, placed in an ice bath and under N2(g), NaNH2 (7.0 g, 0.179 mol) is added to 80 mL of distilled THF. OPCl3 (5.0 mL, 53.6 mmol) is then added with a graduated pipette to form a reaction mixture. The ice bath is removed after 1 d of reaction and the reaction was kept running at room temperature under N2 for 1 week. The reaction mixture remains cloudy due to insoluble NaCl byproduct. Thereafter, the soluble and insoluble parts in the reaction mixture are separated by centrifugation. This results into 50 mL of stable suspension. To obtain the yield of the reaction, a small sample (3 mL) was taken from the solution and vacuum dried at 60° C. on a Schlenk line. The product is a yellow solid with a yield of 0.23 g, the total yield would be 3.8 g, which is about 75% of theoretical yield (5.1 g)
PON Precursor.
PON precursor is heated to different temperatures under N2.
Table below shows the typical FT-IR of PON and LiPON phases.
Based on the structures shown in
Synthesis of LixPON.
Li3PON precursor: Following the synthesis of PON precursor, LiNH2 (3.0 g, 0.13 mol, the calculated amount of —NH in the PON precursor) is added to the suspension of PON precursor [O═P(NH2)3] under N2 while an ice bath is attached. The mixture became cloudy after adding LiNH2 as it is not very soluble in THF. This is all performed under N2. The mixture is kept stirring magnetically under N1. The ice bath is removed after 1 d of reaction.
After a week of reacting, soluble and insoluble parts in the reaction mixture again are separated by centrifugation. This results in 30 mL of a yellow stable suspension. The yield is about 4 g (about 90% of theoretical yield).
Similarly, Li6PON precursor can be synthesized with double the amount of
The source of the νO—H band is unknown. Two possible explanations are that it comes from equilibria between N—H/P═O<->N═P and O—H, or from excess unreacted LiNH2 which reacts with moisture to become LiOH.
Based on the structures shown in
Synthesis of SiPON.
In a 200 ml round bottom Schlenk flask, 80 ml of distilled THF is first collected. (Me3Si)2NH (20.1 ml, 96.6 mmol) and OPCl3 (5.0 ml, 53.6 mmol) are then added via graduated pipettes. All was done in an ice bath under N2. Initially, the reaction mixture is transparent. After 5-10 min of stirring, insoluble solid started to form from the reaction and the mixture became cloudy. The ice bath was removed after 1 d of reacting and the reaction was kept running at 40° C. under N2 for 1 week.
After a week of reacting, the soluble and insoluble parts in the reaction mixture are separated by centrifugation. This results in 60 ml of a transparent solution. A small sample (3 mL) is taken from the solution and vacuum dried at 60° C. on a Schlenk line. The product is a yellow viscous liquid with a yield of 0.3 g, the total yield would be about 6 g, which is ˜95% of theoretical yield (6.3 g).
SiPON precursor.
The spectra after heating to 800° C. are quite different, no νN—H band can be seen, suggesting that the volatile groups were eliminated by evaporation or particle decomposition. The final phase is the same as PON, with νP═O band at about 1250 cm−1, νP—O around 1000 cm−1.
Based on the structures showed in
Synthesis of LixSiPON.
Li3SiPON precursor: Following the synthesis of the SiPON precursor, LiNH2 (2.2 g, 95.8 mol, the calculated amount of —NH in the SiPON precursor) is then added to the SiPON precursor solution under N2 in an ice bath. The reaction mixture stays cloudy due to the low solubility of LiNH2. The ice bath is removed after 1 d of reacting. The reaction kept running at room temperature for 1-2 weeks or kept warming at 40° C. for 1 week.
Thereafter, the reaction mixture of Li3SiPON precursor is centrifuged to separate the liquid and solid parts. This results in a 50 mL of yellow transparent solution. The yield is about 6 g (about 90% of theoretical yield).
Similarly, Li6SiPON precursor can be synthesized with double amount of LiNH2.
LixSiPON Precursors
Based on the structures shown in
Synthesis of SiPHN.
In a 200 mL round bottom Schlenk flask, 80 mL of distilled THF is first collected, Cl6N3P3 (7.5 g, 21.6 mmol) and NH(SiMe3)2 (29.2 mL, 0.14 mol) are added. The ratio of Cl6N3P3 to NH(SiMe3)2 is 1:6.5. All is done in an ice bath under N2. Cl6N3P3 is mainly soluble in THF, after adding with NH(SiMe3)2, the reaction is cloudy. However, the mixture slowly turns transparent and the color turns yellow after reacting overnight, which suggests that a soluble product forms during the reaction. The reaction is kept running at 40° C. under N2 for 1 week.
Thereafter, the reaction mixture of SiPHN precursor is centrifuged to separate the liquid and solid parts. This results into 65 mL of a yellow solution. A small sample (3 mL) is taken from the solution and vacuum dried at 60° C. on a Schlenk line. The product is a yellow viscous liquid with a yield of 0.53 g. The total yield would be 11.4 g, which is ˜80% of theoretical yield (14.3 g).
SiPHN Precursor
Synthesis of LiSiPHN.
Following the synthesis of SiPHN precursor, LiNH2 (3.0 g, 0.13 mol, the calculated amount of —NH in the SiPHN precursor) is added to the SiPHN precursor solution under N2 in an ice bath, no bubbles are generated from the reaction. The reaction mixture stays cloudy due to the low solubility of LiNH2. After 1 d of reacting, the ice bath is removed and changed to an oil bath for heating. The color of the reaction mixture becomes orange. The reaction is kept running at 40° C. under N2 for a week.
Thereafter, the reaction mixture of LiSiPHN precursor is centrifuged to separate the liquid and solid parts. This results in 60 mL of an orange solution. A small sample (3 mL) is taken from the solution and vacuum dried at 60° C. on a Schlenk line. The product is a 0.5 g brown solid. The total yield is calculated to be 10 g, which is 83% of the theoretical yield (12 g).
Li SiPHN Precursors
Based on the structures shown in
Synthesis of Na3SiPON.
NaNH2 (3.8 g, 0.1 mol, equivalent amount of —NH) is added to the solution of SiPON precursor under N2 in an ice bath. A lot of bubbles form from the reaction right after adding NaNH2. The mixture turns yellow after 1 d of reacting.
Na3SiPON precursor
A small sample of the liquid from the Na3SiPON solution is taken and vacuum dried at 40° C. on a Schlenk line. It is then heated to 180° C. under vacuum for 1 h. The product is a brown solid. TGA and FTIR studies are run on the brown solid.
FTIR shows a band at about 3000 cm−1, assigned to νN—H. The sharp peak at 1400 cm−1 is typical for NH4+ (ammonium ions). The peaks near 1200 and 900 cm−1 can be assigned to νP═O and νP—O—P/P—N═P respectively. No peak for νO—H is observed.
The residue is a dark solid.
Synthesis of Li2NaPON.
In a 50 ml round bottom Schlenk flask, NaNH2 (3.5 g, 0.09 mol) is first added to 30 ml of distilled THF. Then OPCl3 (2.5 ml, 0.027 mol) is added with a graduated pipette. All was done in an ice bath under N2. The reaction mixture started to generate bubbles after about 1 min of adding OPCl3, which may be caused by heat generated from the reaction. The mixture also becomes yellow soon after bubbling, showing that reaction is taking place. The ice bath is removed after 1 d of reaction.
After a week of reaction, the soluble and insoluble parts in the reaction mixture are separated by centrifugation. The liquid is an orange solution.
Thereafter, the solution part is taken into another 50 ml Schlenk flask for synthesizing Li2NaPON. LiNH2 (0.74 g, 32.2 mmol) and NaNH2 (0.63 g, 16.1 mmol) are added to the solution under N2 in an ice bath. Bubbles start to generate from the reaction mixture a few seconds after adding the LiNH2 and NaNH2. The reaction mixture stays orange.
Li2NaSiPON precursor
A small sample of the liquid from the Li2NaPON solution is taken and vacuum dried at 40° C. on a Schlenk line. It is then heated to 180° C. under vacuum for 1 h. The product is a brown solid. TGA and FTIR studies are run on the brown solid.
The residue after TGA is a black solid.
Thin Film Substrate Synthesis.
LiAlO2 Powder Synthesis
LiAlO2 nanopowders (NPs) are generated by using liquid flame spray pyrolysis (LF-FSP) apparatus. Lithium propionate and alumatrane are quantitatively mixed at selected molar ratios to result in LiAlO2 composition with 80, 150, and 300 wt. % excess lithium, hereafter referred as LiAlO2+80%, LiAlO2+150% and LiAlO2+300%, respectively. Table 8 shows the number of precursors used for each composition, which are dissolved in ethanol. Resulting NPs are Li short arising from volatility of Li2O from flame temperatures above 1000° C. Hence, excess lithium propionate is introduced to result in a phase pure material. The resulting precursor mixture is dissolved in ethanol to give a 3 wt % ceramic yield solution and the solution is aerosolized with oxygen into a 1.5 m long combustion chamber where it is ignited using methane/oxygen pilot torches. After combustion and cooling, produced NPs are collected downstream in rod-in-tube electrostatic precipitators (ESP) operated at 10 kV.
As-produced produced LiAlO2 nanopowders (10 g, 0.15 mol) are first dispersed in anhydrous ethanol (350 ml) with 2 wt % polyacrylic acid (200 mg, 1.2 mmol) dispersant, using an ultrasonic horn (Vibra-cell VC 505 Sonics & Mater. Inc.) at 100 W for 10 min. The suspension is left to settle for 4 h to allow larger particles to settle. The supernatant is decanted, and the recovered solution is poured into a clean beaker and left to dry overnight in the oven (60° C.). The dried powders are ground in an alumina mortar and pestle.
Thin Film Substrate Processing
A suspension is made by dissolving collected nanopowder (0.7 g), benzyl butyl phthalate (0.13 g), as a plasticizer, poly acrylic acid (0.01 g) as a dispersant, polyvinyl butyral (0.13 g) as a binder in anhydrous ethanol (0.9 ml) and acetone (0.9 ml) to form a mixture. The mixture (2.39 g) is placed in a 20 mL vial and milled with spherical alumina beads (6 g) with 3 mm diameter media overnight to homogenize the suspension. The suspension is cast using a wire wound rod coater (Automatic Film Applicator 1137, Sheen Instrument, Ltd). After solvent evaporation, dried green films are uniaxially pressed in between stainless-steel dies at 100° C. with a pressure of 50-70 MPa for 5 min using a heated bench (Carver, Inc) top press to improve packing density.
Sintering Studies
Heat treatments are conducted in a High-Temperature Vaccum/Gas tube furnace (Richmond, Calif.). Green films of LiAlO2+80%, LiAlO2+150%, and LiAlO2+300% are placed between alumina disks and sintered to 1100° C. for 2 h in air (100 mL min−1).
LATSP (Li1.7Al0.3Ti1.7Si0.4P2.6O12) and LiAlO2 substrates are synthesized. Green films of LATSP are placed in between alumina plates and debindered/crystallized at 665° C./2 h at a ramp rate of 5° C. min−1 followed by sintering at 1000° C./1 h at a ramp rate of 1° C. min−1 under 120 ml min−1 air flow.
Coating Studies
Sintered substrates are dip-coated 1× in the desired precursor (LiPON, a are left to dry for 12 h under vacuum at 100° C. Dried samples were then heated up to selected temperature and atmosphere as shown in
Coating LATSP with PON, SiPON, Li3PON, Li1.5SiPON, Li3SiPON, Li6SiPON.
LATSP substrates are dip-coated 1× in PON, SiPON, Li3PON, Li1.5SiPON, Li3SiPON, Li6SiPON solutions using copper wire to suspend the sample. The coated substrates are left to dry for 12 h/vacuum/100° C. Dried samples are then heated to 300, 400, 500 and 600° C./2 h/N2 at a ramp rate of 5° C./min as shown in
LATSP substrates coated with SiPON and heated to 400° and 600° C. did not show a clear distinguished coating interface. These heating schedules lead to a poor coating for both PON and SiPON precursors. Substrates treated to 500° C. showed coating with an average thickness of 6.8 μm.
LATSP+Li3PON films heated to 500° C. did not show coating interface this might be ascribed to poor coating. However, there is a clear distinguished interface between the coating and the substrate for samples heated to 600° C. with an average coating thickness of 8.8 μm.
Coating treatments with Li3SiPON and Li6SiPON solutions at 500° C. do not show uniform interfaces as they are scarcely distributed. The inconstancy of coating thickness might be ascribed to the uncontrolled process of dip-coating. LATSP substrates coated with Li3SiPON and Li6SiPON and heated to 500° C. show porous coating interfaces suggesting that the coatings are not stable at higher temperatures.
From the fracture surface image of LATSP+ Li6SiPON films heated to 400° C., the coating seems to be percolating through the grain and grain boundaries represented by the white colors. The coating also appears on the surface of the film with an average thickness of 5 μm. All LATSP substrates coated with LixSiPON derivatives and heated to 600° C. show interfaces with island morphologies. The coatings are not uniformly distributed; suggesting that 600° C. might be too high a temperature for LixSiPON derivatives on LATSP substrates.
Table 9 illustrates the total conductivity of LATSP substrates coated with different precursor solutions and heated to 400, 500, and 600° C./2 h/N2. LATSP substrates coated with PON and SiPON show the highest conductivity when heat-treated at 400° C. This might be attributed to the fact that the coating is minimal and is not visible from the fracture surface images shown in
Increasing the heating temperature leads to improved conductivity for Li3PON coatings. The highest conductivity is when samples are heated to 600° C. This heating schedule also leads to good bonding interfaces.
Li1.5SiPON film shows poor conductivity when heat treated to 500° C. and 600° C. due to the porous coating. This solution is not stable in air for coating, thus the resulting substrates suffer from too thick coatings that resulted in poor ionic conductivity.
The Li3SiPON and Li6SiPON solutions give the best conductivity around 400°-500° C. The coatings are not stable when heated to 600° C. as shown by the SEM images in
Coating LiAlO2+X with PON, SiPON, Li3PON, Li1.5SiPON, Li3SiPON, Li6SiPON.
LiAlO2+X substrates are placed between α-alumina disks and heated at 665° C. for 2 h at a ramp rate of 3° C. min−1 followed by sintering to 1100° C./2 h at a ramp rate of 1° C. min−1 in air (100 ml min−1).
LiAlO2+X substrates are dip-coated for 1 min in PON, SiPON, Li3PON, Li1.5SiPON Li3SiPON, and Li6SiPON solutions (3 mL). The coated films are left to dry for 12 h under vacuum at 100° C. Dried samples are then heated up to 500° and 600° C./2 h/N2 at a ramp rate of 1° C./min.
LiAlO2+300%+Li3PON films heated to 400° C. show a clear distinguished interface. However, on heating temperature to 500° C. and 600° C., the coating fades and delaminates as demonstrated from the SEM fracture surface images suggesting that the coating is not stable above 400° C.
The Li6SiPON films heated to 400° C. give porous coatings; however, at 500° C. the coatings are uniform and dense. The bottom part of the substrate did not coat well because a Teflon substrate used to place the films after the dip coating process results in loss of the coating. The Li6SiPON coating is not stable above 500° C. on LATSP and LiAlO2+300% substrates.
Table 10 records the total conductivity of LiAlO2+300% substrates coated with different precursor solutions and heated to 400, 500, and 600° C./2 h/N2. LiAlO2+300% substrates coated with PON and SiPON show the highest conductivities when heat treated at 400° C. with a minimal coating of both precursors, which was also demonstrated when using LATSP substrate. The impedance starts to increase on heating to 500° C. and 600° C., a result of too thick coating for PON thin films. Since these coatings percolate into the substrate when treated to 600° C., the resulting conductivities are poor.
The Li3PON thin films show inverse behavior when LiAlO2+300% is used versus the LATSP substrate. The impedance decreases on heating from 400° C. to 600° C. by two orders of magnitude. This can be attributed to the fact that the coating is not stable at high temperatures; as demonstrated from the delamination of the coating from the
The Li1.5SiPON films shows poor conductivity on heat treating to 400° C. In fact, there is an appearance of a parallel combination of a resistance and a capacitance upon the complex plane as the impedance go all the way down to the real axis at low frequencies. However, the conductivity seems to improve at 600° C.
The Li3SiPON films show conductivity (10−5 S/cm) on heat treating from 400° to 600° C. consistent with the LATSP substrate as well as LiAlO2+300%.
The Li6SiPON solution gives the highest conductivity of 1.4×10−∝+5.2×10−5 S/cm for LiAlO2+300% substrates. The substrate without a coating has a conductivity of 1.6×10−8 S/cm. However, the conductivity drops an order of magnitude when the film is heated above 400° C.
Tables 11 and 12 illustrate the total conductivity of LiAlO2+Li3SiPON coated substrates heated to 300° C. and 400° C./2 h/N2 respectively. Samples treated at higher temperatures show higher conductivities than samples treated at 300° C. This suggests the coating is more stable at 400° C. The total conductivities reported here are three to four orders of magnitude higher than LiAlO2 substrates without the coating.
Coating α-Al2O3 with Li3PON, Li3SiPON, Li6SiPON, Na3SiPON.
α-Al2O3 substrates are dip-coated for 1 min in Li3PON, Li1.5SiPON Li3SiPON, Li6SiPON, and Na3SiPON solutions (3 mL). The coated films are left to dry for 12 h under vacuum at 100° C. Dried samples were then heated up to 400-600° C./2 h/N2 at a ramp rate of 1° C./min.
The Li6SiPON films heated to 400° C. show uniform and thin coatings bonded to the α-Al2O3 substrate. However, as the heating temperature increases the coating starts to become porous and delaminates from the substrate as seen for both LATSP and LiAlO2 substrates.
XRD studies of Li3PON and Li6SiPON.
XPS Studies of Li3PON and Li6SiPON.
Previous XRD studies at 100° C. show mainly amorphous phase, hence the technique cannot detect the targeted elements and does not allow quantification of elemental composition nor the possibility to deduce elemental ratios. Hence XPS studies on the polymer precursors are performed.
XPS analysis also provides information about bonding environments. The O is peak is assigned to oxygen in Li—O—Li, P—O—P, and P═O bonds. XPS analysis indicates that the Li/N ratio increases from about 2.7 to about 3.5 when more LiNH2 is introduced to form Li6PON. The experimental N/P ratio is calculated to be 3, the found ratio from XPS analysis suggests nitrogen is lost during polymerization as suggested by the above condensation reactions. However, the N/P ratio (1.25-1.66) is much higher than reported for gas phase deposition techniques (0.92). XPS measurements further confirm that the Li3PON and Li6PON pellets contain 4.7 and 5.35 at. % of N.
The measured atomic composition shows that the Li/N ratio increases from about 1.43 to about 1.68 when more LiNH2 is introduced for Li6SiPON. However, the ratio is smaller than calculated for Li3PON (2.86) and Li6PON (3.5) pellets. It is likely that the introduction of silicon leads to loss of (Me3Si)2N during condensation polymerization. The experimental ratio of N/P is calculated to be 3, the decrease in the ratio from XPS analysis suggests polymerization by the loss of nitrogen. However, the atomic percent of N is 8.5 and 6.7% for Li3SiPON and Li6SiPON, respectively. The N/P ratio (1.85-2.4) is still higher than what is reported for Li3PON and Li6PON in Table 15.
PEO-Based Polymer Electrolytes.
The PEO polymer with molecular weights of 900 k are dissolved in acetonitrile (18 mL) and stirred magnetically under N2 until fully dissolved. Polymer precursors with weight ratios of 40 were mixed with the PEO/ACN solution and magnetically stirred for 24 hr. The PEO/precursor mixture is then cast on a Teflon plate. Solvent is allowed to evaporate at ambient for 24 h. The film is then dried under a vacuum of 3×10−3 Torr for 24 h at 65° C. Table 16 lists the amount of 60 wt. % PEO/precursor dissolved in 18 ml CAN.
The PEO/polymer precursor ratio is chosen as 60:40 because this composition results in dense films easy to handle and process with optimal conductivity. Higher PEO concentrations result in poorer ionic conductivity while lower PEO concentrations result in poorer mechanical properties.
XPS experiments are carried out on the polymer electrolytes on a Kratos Axis Ultra XPS system at room temperature under 3.1×10−8 Pa using a monochromatic Al source (14 kV and 8 mA). Binding energies of all the elements are calibrated relative to the gold Au 4f7/2 at 84 eV. All the data are analyzed by CASAXPS software using linear type background.
XPS analysis also provides information about elemental bonding environments. The N/P ratio (1.07-1.469) is still higher than what is reported by gas phase deposition techniques (0.92). The C is spectra could be deconvoluted into three Gaussian-Lorentzian mixed components. The binding energy of the carbon in all the polymer composite films coincides with the most intense carbon peak of PEO′ attributed to the carbon on the —CH2—CH2—O-repeat unit. The binding energy of C is is in the order of Li2SiPHN>Li6SiPON>Li6PON.
XRD Studies of 60 PEO/Polymer Precurosr
The polymer composite electrolyte films, as well as pure PEO, are analyzed using a Rigaku rotating anode goniometer (Rigaku Denki., Ltd., Tokyo, Japan). XRD scans a made using the Cu Kα radiation (1.541 Å) operating at 40 kV and 100 mA in the 20 range of 10° to 40° and using a step width of 0.02°. The slower scan rate is used to minimize the signal-noise ratio.
The X-ray spectrum of composite films exhibits peak shifts toward lower diffraction angle compared to pure PEO listed in Table 20. For example, the (112) peak shifts from 19.37° to 19.13° when Li3PON precursor was used. The d-spacing changes from 4.57 to 4.63 Å and this indicated that the distance between two planes (112) was enlarged when the polymer precursor is introduced. The shifting of X-ray peak can be caused by strain or stress. The possible reason for the peak shifting is the presence of the polymer precursor induces stresses that changed d-spacing of PEO crystals. The change could be an indicator of the stress transfer between the polymer precursor and the polymer chains. X-ray spectra data for PEO/LI6PON, PEO/Li2SiPHN, PEO/Li3SiPON, and PEO/Li6SiPON composites compared to pure PEO are listed in Tables 21-24, respectively.
The d-spacing for plane (112) is in increasing order of Li6SiPON>>Li6PON>>Li3PON>>Li2SiPHN>>Li3SiPON>>PEO
The d-spacing for plane (120) is in increasing order of Li2SiPHN>>Li3PON>>Li6S iP ON>>Li6PON>>Li3SiPON>>PEO
The d-spacing for plane (222) is in increasing order of Li6SiPON>>Li3PON>>Li2SiPHN>>Li6PON>>PEO.
The XRD pattern for 60 wt. % PEO/Li3SiPON does not show a peak for (222) plane, and it shows the lowest intensity compared to the other polymer precursor composite films. Hence, this composite polymer electrolyte showed the lowest crystallinity percentage.
Addition of the polymer precursors especially with Me3Si moieties decreases crystallinity of the polymer electrolyte considerably as demonstrated by broadening and reduction of PEO peak intensity as shown in
Table 25 summarizes the total room temperature resistivity of PEO/Li2SiPHN, Li3SiPON, and Li6SiPON composite films heated to 65° C./12 h/Vac. The PEO/Li3SiPON composite film shows the highest conductivity of 2.8 mS/cm when compared to the other polymer precursors. The PEO/precursor composite films 100 μm thick reveal decreases in PEO crystallinity as shown in the
The temperature dependent conductivity of the polymer electrolytes increases with increases in temperature for all PEO/precursor compositions. The activation energy for these composite electrolytes decreases from 0.5 to 0.23 eV for Li2SiPHN vs. Li3PON precursor. This latter value might be ascribed to the amorphous nature of the polymer electrolyte with the addition of secondary PON phase, suppressing the crystallinity of the PEO and facilitating fast Li+ motion.
Symmetric Cell Studies
Symmetric Li/60 wt. % PEO+Li3PON and Li6SiPON/Li cells were assembled in a glovebox under Argon. Before cell assembly, Li metal was heated to 175° C. for 2 h, and 60 wt. % PEO+Li3PON and Li6SiPON polymer electrolyte were melt bonded onto the Li.
CELGARD® separator coated with new batch Li3PON, Li6PON, Li2SiPHN, Li3SiPON and Li6SiPON.
CELGARD® separator Li-ion battery separator film (25 μm thick×18 mm diameter) substrates are dip-coated 1x in the precursor in Li3PON, Li6PON, Li2SiPHN, Li3SiPON, and Li6SiPON solutions using copper wire to suspend the sample. This experiment is conducted to measure the impedance of the polymer coatings without any heat treatments; which is similar to measuring the impedance of conventional liquid electrolyte.
From these preliminary results, it can be concluded that the polymer precursors have optimal lithium ion diffusivity through the separator. Thus, they can be used to wet the cathode electrodes when all-solid state batteries are assembled. The wet conductivity results are Li2SiPHN<<Li3PON<<Li6SiPON<<Li3SiPON<Li6PON. The Li6PON precursor is a suitable electrolyte to be used when assembling a half-cell.
Li/Polymer Coated Separator/Li
A symmetric Li/CELGARD® separator+, Li3PON, Li6PON, Li3SiPON, and Li6SiPON/Li cells are assembled in a glovebox at UMEI under Argon flow. Before cell assembly, the metallic Li (16 mm diameter) is scraped to expose a clean surface. Symmetric cells are constructed using the standard procedure in a coin cell. The coin cells are compressed using a about 300 kPa uniaxial pressure. The symmetric cells are cycled at room temperature using a potentiostat/galvanostat (BioLogic SP300). The solution of polymer precursors dissolve in THF (20 μL) are used as an electrolyte.
The CELGARD® separator coated with Li6PON polymer precursors shows unstable voltage spikes when 0.1 mA current density is used. Higher current densities (0.1 mA) seem to result in higher interfacial impedance as presented by the increase in voltage response to 1V. However, the symmetric cell shows a stable voltage response (0.25 V) when the lower current density of 0.075 mA is used as shown in
Li2SiPHN
Li2SiPHN precursor is heated to 80° C./Vacuum. The resulting dried Li2SiPHN (1 g) powder is compacted into a pellet using 3 mm diameter die. The resulted pellets are heated between alumina plates to 100-600° C./2 h at a ramp rate of 1° C. min−1 under 120 ml min−1 N2 flow.
Table 29 illustrates the total ionic conductivities of a Li2SiPHN pellet heated to selected temperatures. Ionic conductivities of about 7×10−5S cm−1 are obtained when films are heated to 100° C.
LIAlO2 substrates coated with Li2SiPHN do not show consistent conductivity when heat treated to 100-300° C. This can be ascribed to the fact that the coating is not stable in air and that the precursor suspension precipitates while coating. The conductivity drops in two orders of magnitude when treated from 100-300° C.
Polymer precursor reactions for LiAlOx.
The first step is to develop a model system as illustrated immediately below.
This reaction successfully produces an ethanol soluble aluminate. The use of excess LiO2CCH2CH3 can provide, on thermal decomposition, LixAlOy where x>1. On solvent removal the aluminate complex is a crystalline solid that would be difficult to use for coatings unless it melts on heating.
Characterization Data
In a sample vial, 1 g of lithium propionate is added with 5.93 g of alumatrane (in EtOH), the ratio of Li:Al is 1:1 according to TGA results, about 10 mL more EtOH is added to the mixture. The reaction mixture is heated up to about 50° C. for 1 h while stirring magnetically. The solution becomes transparent.
Thereafter, the solvent is removed by rotatory evaporation, and the residue is vacuum dried in a vacuum oven at about 60° C. The yield is 3.0 g of yellow (or orange) solid.
TGA/DTA (1000° C./air) on the LiAlOx precursor shows a ceramic yield of 20.6% at 1000° C. The mass loss suggests that it decomposes around 350° C. leaving an intermediate char phase that oxidizes on heating from 430° C. to 580° C., slowly losing CO2 (or oxidation of residual carbon), then it decomposes again and remains stable from 630° C. The residue is an LiOAl compound (LiAlO2).
Lithium Aluminate from Polyacrylic Acid.
As an alternative to the LiO2CCH2CH3 component, it is also possible to make a polyacrylic acid (PAA) derivative as shown immediately below.
The PAA derivative can then be reacted with alumatrane to produce a processable polymer precursor as shown immediately below.
The ratio of Li to Al can be controlled by the stoichiometry of this reaction. Less alumatrane gives more Li in the LixAlOy material to be produced.
Characterization Data
In a 100 ml round bottom flask, PAA (2.5 g, 1.25 mmol) and Li2CO3 (1.3 g, 17.3 mmol) are added with 30 mL of EtOH. The ratio of —CO2H group to Li2CO3 is 2:1. The reaction is kept stirring magnetically under N2 while heating at 60° C. with a reflux condenser.
The reaction mixture stays cloudy after 1 week of reacting, meaning that the reaction mixture is not very soluble in EtOH. Then 5 mL DI water is added to the reaction. A few minutes after adding the water, the solution clears up, but a white solid bulk forms, and it is floating on the surface of the solution. Gas also comes out from the reaction, which should be CO2. The reaction is kept running at 60° C. After 5 d of reacting with water, the white solid sinks down to the bottom, meaning no more CO2 is forming, the reaction is over. The solid is taken out from the reaction and a test on a small sample shows that it is water soluble.
The solid is then put into vacuum oven and dried at 60° C. for a few days. The yield of the product is 2.4 g after drying, and the theoretical yield is 2.7 g.
Synthesis of MgSiPON.
In a 50 ml round bottom Schlenk flask, NaNH2 (2.1 g, 0.06 mol) and OPCl3 (1.5 ml, 16.1 mmol) are added to 20 ml of distilled THF under N2 in an ice bath to form a reaction mixture. The reaction mixture becomes yellow about 5 min after reacting, showing that a reaction is taking place. The ice bath is removed after about 1 day of reacting.
After a week of reacting, soluble and insoluble parts in the reaction mixture are separated by centrifugation. The resulting liquid is an orange colored solution.
Thereafter, the solution is transferred into another 50 ml Schlenk flask. Mg(NSi2Me6)2 (5.0 g, 14.5 mmol, about 90% equivalent amount of OPCl3) is added to the solution under N2 in an ice bath. No bubbles generated from the reaction mixture. The color of the reaction mixture turns dark after about 10 min of reacting. The reaction mixture remains a transparent solution, and no insoluble part forms. The ice bath is removed after 1 day of reacting.
MgSiPON Precursor.
A small sample of the liquid from the MgSiPON solution is taken and vacuum dried at 40° C. on a Schlenk line, then heated to 180° C. under vacuum for 1 h. The product is an orange solid. TGA and FTIR studies are run on the orange solid.
As shown in
The residue is a dark solid. As shown in
Precursors Used to Bond Different Components for Solid State Battery Assembly.
Because a precursor can be applied to multiple surfaces, it can be used to mate surfaces in its precursor form, such that on heating two mated surfaces, a ceramic ionic electrolyte bond is created.
Cathode+Precursor Electrolyte+Ceramic Electrolyte.
The precursor described here is Na3SiPON.
Na0.8CoO2 (NCO)+Na3SiPON+Na3.1Zr1.95Mg0.05Si2PO12 (NZMSP).
Li4Ti5O12+Li3SiPON+LiAlO2+300%.
The interfacial behavior directly dictates the lifespan, energy density, and safety of all solid state batteries. These coatings might lower the interfacial resistance and stabilize the interfacial performance between SSE/electrode.
LiAlO2+300% green films are placed between α-alumina disks and heated at 665° C. for 2 h at a ramp rate of 3° C. min−1, followed by sintering to 1100° C./2 h at a ramp rate of 1° C. min−1 in air (100 ml min−1).
LiAlO2+300% films are dip-coated for 1 min in Li3SiPON solution and bonded to LTO films. The resulting anode-electrolyte are left to dry for 12 h under vacuum at 100° C. Dried samples are then heated up to 400° C./2 h/N2 at a ramp rate of 1° C./min.
LTO+Li3SiPON+LATSP.
Green films of LATSP are placed in between alumina plates and debindered/crystallized at 665° C./2 h at a ramp rate of 5° C. min−1 followed by sintering at 1000° C./1 h at a ramp rate of 1° C. min−1 under 120 ml min−1 air flow.
LATSP films are dip-coated for 1 min in Li3SiPON solution and bonded to LTO films. The resulting anode-electrolyte are left to dry for 12 h under vacuum at 100° C. Dried samples are then heated up to 400° C./2 h/N2 at a ramp rate of 1° C./min.
Since LATSP is unstable against Li metal at high temperatures, an alternative anode material (LTO) is examined.
Precursor Used to Coat Particles of Cathode Materials.
LCO+LSP+Ag.
The main components of the electrodes are the active material and the electrolyte. When formulating composite cathodes, it is important that the content of the active material should be high as possible to increase the capacity. However, lowering the electrolyte content decreases the conduction path, and thus, decreases the utilization rate of the active materials, owing to limited charge transfer.
In order to optimize the electrode structure, a new composite cathode is formulated using commercial LiCoO2 powder, LSP nanopowder, Ag, and Li3PON and Li3SiPON precursor solutions.
Table 31 lists components used for making a suspension of LCO/LSP/Ag, with target volume fractions of 67/27/6 respectively. All the components are added to a 20 mL vial and ball-milled with 3.0 mm diameter ZrO2 beads (6 g) for 24 h to homogenize the suspension. The suspension is cast using a wire wound rod coater. Died green films are thermo-pressed at 50° C. with a pressure of 100 MPa for 5 min using a heated bench top press.
The resulting composite cathode is heated to 500° C./1 h/air for carbon burn out, then soaked for 1 min in Li3SiPON and Li3PON solution. The resulting composite cathode soaked in precursor electrolyte was left to dry for 12 h under vacuum at 100° C. Dried samples are then heated up to 400° C./2 h/N2 at a ramp rate of 1° C./min.
Coating of a Mg Conducting Ceramic with an Mg Electrolyte.
MZP:Fe+MgSiPON.
MZP:Fe green films are placed between α-alumina disks and sintered to 900° C. for 3 h at a ramp rate of 3° C. min−1 in air (100 ml min−1). MZP:Fe films are dip-coated for 1 min in MgSiPON solution. The resulting coated films are left to dry for 12 h under vacuum at 100° C. Dried samples are then heated up to 400° C./2 h/N2 at a ramp rate of 1° C./min.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
This application claims the benefit of U.S. Provisional Application No. 62/725,731 filed on Aug. 31, 2018. The entire disclosure of the above application is incorporated herein by reference.
This invention was made with government support under EE0008235 awarded by the Department of Energy and 19-PAF04357 awarded by the National Science Foundation. The government has certain rights in the invention.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2019/049155 | 8/30/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62725731 | Aug 2018 | US |
