Patent Application
20240266521
This disclosure is in the field of materials useful in chemical energy storage and power devices such as, but not limited to, batteries. More specifically, this disclosure relates to acidified metal oxide (“AMO”) nanomaterials and battery cells with a cathode and/or an anode comprising the AMO nanomaterials.
Metal oxides are compounds in which oxygen is bonded to metal, having a general formula MmOx. They are found in nature but can be artificially synthesized. In synthetic metal oxides the method of synthesis can have broad effects on the nature of the surface, including its acid/base characteristics. A change in the character of the surface can alter the properties of the oxide, affecting such things as its catalytic activity and electron mobility. The mechanisms by which the surface controls reactivity, however, are not always well characterized or understood. In photocatalysis, for example, the surface hydroxyl groups are thought to promote electron transfer from the conduction band to chemisorbed oxygen molecules.
Despite the importance of surface characteristics, the metal oxide literature, both scientific papers and patents, is largely devoted to creating new, nanoscale, crystalline forms of metal oxides for improved energy storage and power applications. Metal oxide surface characteristics are ignored and, outside of the chemical catalysis literature, very little innovation is directed toward controlling or altering the surfaces of known metal oxides to achieve performance goals.
The chemical catalysis literature is largely devoted to the creation of “superacids”—e.g., acidity greater than that of pure sulfuric acid (18.4 M H2SO4)—often used for large-scale reactions such as hydrocarbon cracking. Superacidity cannot be measured on the traditional pH scale and is instead quantified by Hammet numbers. Hammet numbers (H0) can be thought of as extending the pH scale into negative numbers below zero. Pure sulfuric acid has an H0 of −12.
There are, however, many reaction systems and many applications for which superacidity is too strong. Superacidity may, for example, degrade system components or catalyze unwanted side reactions. However, acidity may still be useful in these same applications to provide enhanced reactivity and rate characteristics or improved electron mobility.
The battery literature teaches that acidic groups are detrimental in batteries, where they can attack metal current collectors and housings and cause deterioration in other electrode components. Further, the prior art teaches that an active, catalytic electrode surface leads to electrolyte decomposition which can result in gas generation within the cell and ultimately in cell failure.
A need exists for improved batteries and associated components.
Described herein are compositions useful in electrochemical cell electrodes, such as a cathode or an anode. The disclosed compositions generally comprise solid nanoparticles of a metal oxide with electron withdrawing groups on their surface. The disclosed compositions are useful as active materials, such as in a lithium-ion battery system. In specific examples, the disclosed compositions comprise nanoparticles of a surface-functionalized solid metal oxide, such as nanoparticles having an average diameter of less than one micron. The nanoparticles may comprise oxygen and a metal and one or plurality of electron withdrawing groups, such as where the surface of the nanoparticles is functionalized by the electron withdrawing groups.
A variety of different electron withdrawing groups can be used. For example, the electron withdrawing groups may be one or more of: Cl, ClO, ClO2, ClO3, ClO4, or hydrogenated forms thereof; Br, BrO, BrO2, BrO3, BrO4, or hydrogenated forms thereof; I or IO3; F; S, SO2, SO3, SO4, or hydrogenated forms thereof; N, NO, NO2, NO3, or hydrogenated forms thereof; PO3, PO4, or hydrogenated forms thereof; BO3 or HBO3; CN, SCN, or OCN; or COO, CH3COO, CO3, HCO3, C2O4, C6H7O7, C2H5CO2, C3H7CO2, or C4H9CO2. In some examples, the electron withdrawing group is one or more of Cl, Br, BO3, NO3, SO4, C2H3O2, C2O4, or C6H5O7. In some examples, the electron withdrawing group is not hydroxide or hydroxyl (OH) and/or is different from hydroxide or hydroxyl (OH). In some examples, the electron withdrawing group has a molecular weight less than 200 Da.
The nanoparticles may have any suitable shapes, sizes, or distributions. In some examples, the average diameter of the nanoparticles may be from 1 nm to 1000 nm, such as 100 nm or less, 20 nm or less, or 10 nm or less. Optionally, the nanoparticles comprise monodispersed particles. Optionally, the nanoparticles are in the form of agglomerates, an interconnected porous matrix, or dispersed individual particles. Optionally, the nanoparticles exhibit an amorphous character, a crystalline character, or a mixture of amorphous and crystalline characters. Optionally, the nanoparticles exhibit plate or plate-like morphologies, spherical or spherical-like morphologies, needle or needle-like morphologies, or rod or rod-like morphologies.
With respect to a metal oxide composition of the nanoparticles, the metal component may be selected from iron, tin, antimony, bismuth, titanium, zirconium, manganese, indium, lithium, or a combination of these. Optionally, the metal is selected from tin, titanium, iron, or zirconium, or a combination of these. Optionally, the nanoparticles correspond to mixed metal oxide nanoparticles comprising oxygen and a plurality of different metals. Optionally, the metals may include includes tin and iron, antimony and tin, aluminum and tin, lithium and iron, or lithium and tin. In other examples, the nanoparticles have or are characterized by a composition of the formula MmNnRrOx/G, where M is a first metal, N is a second metal, R is a third metal, G is the electron withdrawing group, m is from 1 to 5, n is from 0 to 5 (e.g., greater than 0 and less than or up to 5), r is from 0 to 5 (e.g., greater than 0 and less than or up to 5), x represents total oxygen associated with metals M, N, and R and may be greater than 0, such as from 1 to 2, from 2 to 3, from 3 to 4, from 4 to 5, from 5 to 6, from 6 to 7, from 7 to 8, from 8 to 9, from 9 to 10, or from 10 to 21, “/” indicates a distinction between the metal oxide and the electron withdrawing group and denotes no fixed mathematical relationship or ratio between them. In some examples, n and/or r may be zero, such that formula for the composition of the nanoparticles may be MmNnOx/G or MmRrOx/G or MmOx/G. In some examples, nanoparticles of a first composition may be mixed with nanoparticles of a second composition, such as where one or more metals in the second composition are different from the first composition and/or where one or more electron withdrawing groups in the second composition are different from the first composition. In examples, a mixture of different nanoparticle compositions may comprise a mixture of MmNnOx/G1 or MmRrOx/G2, where G1 and G2 are the same or different electron withdrawing groups.
The nanoparticles may be characterized, in some examples, by an acidity. For example, the acidity of the nanoparticles may be characteristic of a surface acidity of the nanoparticles. In some examples, the acidity of the nanoparticles may be characterized by the acidity, pH, or Hammet Function (H0) of a solution in which the nanoparticles, in dried form, are suspended or re-suspended in water at 5 wt. %. In examples, the nanoparticles comprise acidified metal oxide nanoparticles that are not super acidic. Optionally, the nanoparticles exhibit a pH, optionally a surface pH, less than 7 and a Hammet Function (H0) greater than −12. Optionally, the nanoparticles exhibit a pH less than 7 and a Hammet Function (H0) greater than −12 when a dried form of the nanoparticles is suspended in water at 5 wt. %, such as at room temperature.
The disclosed compositions are useful in mixed electrode or composite electrode systems. In some examples, such as where the metal oxide nanoparticles are mixed with other materials, such as additives. In some examples, a mixture or composite may comprise the composition described herein, such as a surface-functionalized metal oxide or acidified metal oxide nanoparticles, in addition to one or more of a non-acidified metal oxide, a binder, or a conductive aid.
Optionally, the mixture or composite may be combined in the form of or used as an electrode for a battery. For example, the electrode may be paired with a counter electrode and an electrolyte positioned between the electrode and the counter electrode to form a battery. In examples, when the electrode containing the mixture of composite including the surface-functionalized metal oxide or acidified metal oxide nanoparticles is a cathode, the counter electrode may be an anode; similarly, when the electrode containing the mixture of composite including the surface-functionalized metal oxide or acidified metal oxide nanoparticles is an anode, the counter electrode may be a cathode. In examples the battery may be a single-use (primary) battery or a rechargeable (secondary) battery.
In some examples, the amount of the composition of surface-functionalized metal oxide or acidified metal oxide nanoparticles in the electrode may be relatively high, such as from 33 wt. % to 95 wt. % (e.g., about 33 wt. %, 50 wt. %, 80 wt. %, 90 wt. %, or 95 wt. %). In some examples, the amount of the composition of surface-functionalized metal oxide or acidified metal oxide nanoparticles in the electrode may be relatively low, such as from 0.01 wt. % to 10 wt. % (e.g., about 1 wt. %, 5 wt. %, or 10 wt. %), or from 1 wt. % to 20 wt. %, or less than 80 wt. %, or less than 65 wt. %.
Optionally, the surface-functionalized metal oxide or acidified metal oxide nanoparticles may be combined with other metal oxides (e.g., non-acidified metal oxides), such as in the form of dopants (e.g., 0.01 wt. % to 10 wt. %), such as in an electrode comprising a conventional cathode material used in a lithium or lithium-ion battery (e.g., lithium cobalt oxide, (LiCoO2 or LCO), lithium manganese oxide (LiMn2O4 or LMO), lithium nickel oxide (LiNiO2 or LNO), lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate (LFP), or lithium nickel cobalt aluminum oxide (NCA).
In examples, the counter electrode may be or comprise a conventional electrode for a lithium or lithium-ion battery. In examples where the surface-functionalized metal oxide or acidified metal oxide nanoparticles are incorporated into a cathode, the anode may comprise graphite or lithium metal. In examples, the anode may comprise at least 50% metallic lithium when the battery cell is constructed (e.g., metallic lithium that is not reacted with other elements at the time of construction of the battery).
Use of the disclosed surface-functionalized metal oxide nanoparticles described herein in battery systems can result in enhanced battery performance. In some examples, the battery may have a cyclability against lithium metal of at least 150 to 200 charge-discharge cycles.
Without wishing to be bound by any particular theory, there can be discussion herein of beliefs or understandings of underlying principles relating to the invention. It is recognized that regardless of the ultimate correctness of any mechanistic explanation or hypothesis, an embodiment of the invention can nonetheless be operative and useful.
In general, the terms and phrases used herein have their art-recognized meaning, which can be found by reference to standard texts, journal references and contexts known to those skilled in the art. The following definitions are provided to clarify their specific use in the context of the invention.
Acidic oxide—a term used generally in the scientific literature to refer to binary compounds of oxygen with a nonmetallic element. An example is carbon dioxide, CO2. The oxides of some metalloids (e.g., Si, Te, Po) also have weakly acidic properties in their pure molecular state.
Acidified metal oxide (“AMO”), AMO nanomaterial, or AMO material—terms used herein to denote binary compounds of oxygen with a metallic element which has been synthesized or modified to have an acidity greater than that of its natural mineralogical state and also a Hammet function, H0, greater than −12 (i.e., not superacidic). It will be appreciated that AMOs may have a pH or surface pH less than 7, such as when suspended in water (or resuspended in water after drying) at 5 wt. %. Optionally, AMOs may exhibit a pH or surface pH less than 6, less than 5, less than 4 or less than 3. The average particle size of the AMOs disclosed herein is also less than that of the natural mineralogical state. For example, AMOs may comprise nanomaterials, such as particles having at least one dimension less than 1 μm, less than 100 nm, less than 20 nm, less than 10 nm, or falling between 1 nm and 100 nm or between 1 nm and 1000 nm. In some examples, the particles may have average diameters less than or equal to 1000 nm, optionally in a range of 1 nm to 100 nm. In some examples, larger particles may be included in a distribution of particles of AMOs. The particles may be dispersed individual particles or agglomerates. Naturally occurring mineralogical forms do not fall within the scope of the inventive AMO material. A synthesized metal oxide, however, that is more acidic than its most abundant naturally occurring mineralogical form (of equivalent base stoichiometry), but not superacidic, falls within the bounds of this disclosure and can be said to be an AMO material provided it satisfies certain other conditions discussed in this disclosure.
Acidic—a term used generally in the scientific literature to refer to compounds having a pH of less than 7 in aqueous solution.
Battery, battery cell, electrochemical cell, cell—terms that are generally used herein interchangeably to refer to a device comprising a cathode, anode, and electrolyte between them to allow for electrical energy to be stored or discharged through the transfer of electrons and ions between the anode and the cathode. In some cases, a battery may refer to devices including a plurality of electrochemical cells, but a device including a single electrochemical cell may still be referred to as a battery.
Electron-withdrawing group (“EWG”)—an atom or molecular group that draws electron density towards itself. The strength of the EWG is based upon its known behavior in chemical reactions. Halogens, for example, are known to be strong EWGs. Organic acid groups such as acetate are known to be weakly electron withdrawing.
Hammet function—An additional means of quantifying acidity in highly concentrated acid solutions and in superacids, the acidity being defined by the following equation: H0=pKBH++log([B]/[BH+]). On this scale, pure 18.4 molar H2SO4 has a H0 value of −12. The value H0=−12 for pure sulfuric acid must not be interpreted as pH=−12, instead it means that the acid species present has a protonating ability equivalent to H3O+ at a fictitious (ideal) concentration of 1012 mol/L, as measured by its ability to protonate weak bases. The Hammet acidity function avoids water in its equation. It is used herein to provide a quantitative means of distinguishing the AMO material from superacids. The Hammet function can be correlated with colorimetric indicator tests and temperature programmed desorption results. The Hammet function may also be referred to herein as a Hammet number.
Metal oxide—a term used generally in the scientific literature to refer to binary compounds of oxygen with a metallic element. Depending on their position in the periodic table, metal oxides range from weakly basic to amphoteric (showing both acidic and basic properties) in their pure molecular state. Weakly basic metal oxides are the oxides of lithium, sodium, magnesium, potassium, calcium, rubidium, strontium, indium, cesium, barium, and tellurium. Amphoteric oxides are those of beryllium, aluminum, gallium, germanium, astatine, tin, antimony, lead, and bismuth. These and other metal oxides may optionally be useful as AMO materials.
Metallic lithium—a term that refers to lithium in its neutral atomic state (e.g., non-ionic state). The term metallic lithium is intended to distinguish over other forms of lithium including lithium ions and lithium compounds. The term metallic lithium may refer to neutral atomic lithium present in mixtures that comprise lithium atoms, such as mixtures of lithium and other elements, compounds, or substances. The term metallic lithium may refer to neutral atomic lithium present in lithium alloys, such as a metallic mixture including lithium and one or more other metals. The term metallic lithium may refer to neutral atomic lithium present in composite structures including lithium and one or more other materials. Electrodes comprising or including metallic lithium may include other materials besides lithium, but it will be appreciated that metallic lithium may correspond to an active material of such an electrode. In some cases, an anode in an electrochemical cell comprises metallic lithium.
Monodisperse—characterized by particles of uniform size which are substantially separated from one another, not agglomerated as grains of a larger particle. Monodisperse particles may have a uniform size distribution, such as where at least 90% of the distribution of particle sizes lies within 5% of the median particle size.
pH—a functional numeric scale used generally in the scientific literature to specify the acidity or alkalinity of an aqueous solution. It is the negative of the logarithm of the concentration of the hydronium ion [H3O+]. As used herein, pH may be used to describe the relative acidity of nanoparticles suspended in aqueous solution.
Surface functionalization—attachment of small atoms or molecular groups to the surface of a material. In some examples, AMO material may be surface functionalized by covalently bonding EWGs to the surface of the AMO material.
Superacid—substances that are more acidic than 100% H2SO4, having a Hammet function, H0, less than −12.
Described herein are electrochemical cells and cell components, such as electrodes, for such cells. The disclosed electrochemical cells and electrodes comprise acidified metal oxide (“AMO”) nanomaterials, including examples that exhibit high capacity. In some examples, the AMO nanomaterials are provided at a relatively low loading (weight percent) in the electrodes, such as at weight percents less than 30%, with the majority of the remainder of the electrodes comprising conductive materials, binders, or other additives or components. Even with such low loadings, capacities of greater than 10,000 mAh/g AMO nanomaterial have been observed. The electrodes may be provided in layered or non-layered configurations. Example layered configurations include separate layers including AMO nanomaterial and low loading or non-AMO containing layers. The layering of electrodes is entirely optional, however, and high capacities are observed in both layered and non-layered electrodes.
Referring now to
The cell 100 provides a cathode 104 and an anode 106. The contents of the cell 100 undergo a chemical reaction when a conduction path is provided between the cathode 104 and anode 106 that is external to the cell 100, such as by way of element 115. As a result of the chemical reaction, electrons are provided from the anode 106 and flow through element 115 (sometimes referred to as a load) to the cathode 104 via the circuit provided external to the cell. At a basic level, during discharge of the cell 100, the materials comprising the anode 106 are oxidized providing the electrons that flow through the circuit. The materials comprising the cathode 104, as recipient of the electrons given up by the anode 106, are reduced.
Within the cell 100, during discharge, metal cations move through an electrolyte 108 from the anode 106 to the cathode 104. In the case of a lithium-based battery, the metallic cation may be a lithium cation (Li+). The electrolyte 108 may be a liquid electrolyte such as a lithium salt in an organic solvent (e.g., LiClO4 in ethylene carbonate). Other lithium-based electrolyte/solvent combinations may be used as are known in the art. In some cases the electrolyte 108 may be a solid electrolyte such as a lithium salt in a polyethylene oxide. Optionally, the electrolyte may comprise a polymer electrolyte. Example electrolytes include those described in U.S. Patent Application Publication 2017/0069931, which is hereby incorporated by reference.
A separator 110 may be employed to prevent contact between the electrodes 104, 106. The separator 110 may be a porous layer of material that is permeable to the lithium ions and the electrolyte 108 but not otherwise electrically conductive so as to prevent internal shorting of the cell 100. As is known in the art, the separator 110 may comprise glass fibers or may comprise a polymer, possibly with a semi-crystalline structure. Additional components, such as current collectors, may also be included in the cell 100, but are not shown in
Together the anode 104, cathode 106, electrolyte 108, and separator 110 form the completed cell 100. When the separator 110 is porous, the electrolyte 108 may flow into, or be contained by, the separator 110. Under normal operating conditions, the porosity of the separator 110 allows for ion (Li+) flow between the electrodes 104, 106 via the electrolyte 108. As is known in the art, a separator can be constructed so as to melt and close the internal pore structure to shut down the cell in the event of exposure to excess heat or a runaway exothermic reaction.
Most lithium-based cells are so-called secondary batteries. They can be discharged and recharged many times before the chemical or structural integrity of the cell falls below acceptable limits. Cells and batteries according to the present disclosure are considered to be both primary (e.g., single use) and secondary (e.g., rechargeable) batteries.
In the case of the cell 100 being a secondary cell (or part of a secondary battery) it should be understood that the cell 100 may be recharged either alone or as a component of a completed system wherein multiple cells are recharged simultaneously (and possibly in the same parallel or series circuit).
A reverse voltage is applied to the cell 100 in order to effect charging. It should be understood that various schemes for effective recharging of lithium batteries can be employed. Constant current, variable current, constant voltage, variable voltage, partial duty cycles, etc., may be employed. The present disclosure is not intended to be limited to a particular charging methodology unless stated in the claims. During charging of cell 100, element 115 represents a voltage source that is applied between cathode 104 and anode 106 to provide electrons from cathode 105 to anode 106 and allow chemical reactions to take place. Lithium ions are shuttled from cathode 104 to the anode 106 through electrolyte 108 and separator 110.
As examples, cathode 104 or anode 106 may independently comprise an AMO material disclosed herein. For use of a cathode comprising an AMO material, an anode may correspond to lithium metal or a lithium intercalation material, such as graphite. Optionally, electrolyte 108 may include an acidic species, such as dissolved in an organic solvent with a lithium salt. In addition to or alternative to use of an acidic species in electrolyte 108, an electrode (e.g., cathode 104 or anode 106) may optionally comprise an AMO and an acidic species. Oxalic acid is an exemplary acidic species.
Without wishing to be bound by any theory, it is believed that the presence of acidic species in the cathode 104 or anode 106 and/or electrolyte 108 improves a surface affinity of the AMO material toward lithium ions, resulting in an improved ability to take up lithium ions during discharge and overall improvement to capacity as compared to a similar cell lacking acidic species or having a basified electrode or electrolyte (e.g., including basic species). Alternatively or additionally, the presence of acidic species may allow for or otherwise enable additional active sites for lithium uptake in cathode 104. It will be appreciated, however, that the presence of additional acidic species in the cathode 104 or the electrolyte 108, may not be desirable in all embodiments.
It should be understood that
Current collectors known in the art and other components (not shown) may also be relied upon to form a cell 100 into a commercially viable package. Although overall shape or geometry may vary, a cell or battery will normally, at some location or cross section, contain the electrodes 104, 106 separated rather than touching, and have the electrolyte 108 and possibly separator 110 between them. Cells may also be constructed such that there are multiple layers of anodes and cathodes. Cells may be constructed such that two cathodes are on opposite sides of a single anode or vice versa.
A functional or operational battery intended for a specific purpose may comprise a plurality of cells arranged according to the needs of a particular application. An example of such a battery is shown schematically in
A positive electrode 306 may be accessible on the outside of a casing 302 of the battery 300. A negative electrode 304 is also provided. The physical form factor of the electrodes 304, 306 may vary according to application. Various binders, glues, tapes and/or other securement mechanisms (not shown) may be employed within a battery casing 302 to stabilize the other components. Batteries based on lithium technology are generally operable, rechargeable, and storable in any orientation (if a secondary cell). As discussed above, cells 100 may take on various different geometric shapes. Thus,
The battery 300 may also comprise various adjunct circuitry 308 interposing the positive electrode 306 and the lithium cells 100 within the casing 302 of the battery 300. In other examples, the adjunct circuitry 308 interposes the negative electrode 304 and the lithium cells 100 instead of, or in addition to, interposing the positive electrode 306 and the lithium cells 100. The adjunct circuitry 308 may include short circuit protection, overcharge protection, overheating shutdown, or other circuitry as is known in the art to protect the battery 300, the cells 100, and/or any load attached to the battery 300.
The composition of materials chosen for the cathode 104, anode 106, and electrolyte are critical to the performance of the cell 100 and any battery of which it forms a part. In the context of the present disclosure, various examples of AMOs and methods for their production are provided in this regard. These AMOs are suitable for use in forming anodes or cathodes in half cells, cells, and batteries. The AMOs of the present disclosure are otherwise compatible with known lithium cell technology including existing anode and cathode compositions, electrolyte formulations, and separator compositions.
In the context of the present disclosure, various examples of AMOs and methods for their production and use are provided. These AMOs are suitable for use in forming cathodes or anodes in half cells, cells, and batteries. The disclosed AMOs are otherwise compatible with conventional lithium battery technology, including existing anode compositions, cathode compositions, electrolyte formulations, and separator compositions. It will be appreciated that the material of the anode 106 chosen for a cell or battery according to the present disclosure may be less electronegative than the material of the cathode to suitably complement the cathodic materials. In one particular example, the disclosed AMOs are useful as a cathode in a cell having a lithium metal anode.
In various examples of the present disclosure, the cathode 104 comprises an AMO material having a surface that is acidic but not superacidic. This directly contrasts materials previously known and utilized as cathodes such as lithium cobalt or lithium manganese materials. The AMO materials of the present disclosure and methods for their production are described below. In other examples, the anode 106 comprises an AMO material of the present disclosure having a surface that is acidic but not super acidic.
The surfaces of metal oxides are ideally arrays of metal and oxygen centers, ordered according to the crystalline structure of the oxide. In reality, the arrays are imperfect, being prone to vacancies, distortion, and the effects of surface attachments. Regardless, any exposed metal centers are cationic (positively charged) and can accept electrons, thus functioning, by definition, as Lewis acid sites. Oxygen centers are anionic (negatively charged) and act as Lewis base sites to donate electrons. This allows metal oxide surfaces to behave in an amphoteric fashion.
Under normal atmospheric conditions, water vapor will adsorb to the metal oxide surface either molecularly (hydration) or dissociatively (hydroxylation). Both OH and H species can adsorb on the oxide surface. The negatively charged hydroxyl species will attach at the metal, cationic (Lewis acid, electron accepting) centers, and the H′ will attach at the oxygen, anionic (Lewis base, electron donating) centers. Both adsorptions lead to the presence of the same functional group—a hydroxyl—on the metal oxide surface.
These surface hydroxyl groups can serve as either Brønsted acids or as Brønsted bases, because the groups can either give up or accept a proton. The tendency of an individual hydroxyl group to be a proton donor or a proton acceptor is affected by the coordination of the metal cation or oxygen anion to which it is attached. Imperfections of the metal oxide surface such as oxygen vacancies, or coordination of the surface groups with other chemical species, mean that all cations and anions are not equally coordinated. Acid-base sites will vary in number and in strength. When broadly “totaled” across the surface of the oxide, this can give the surface an overall acidic or basic character.
The quantity and strength of Lewis acid and base sites (from the exposed metal cations and oxygen anions, respectively) and Brønsted acid and base sites (from the surface hydroxyl groups)—add broad utility and functionality to the metal oxide and its use in both chemical reactions and device applications. The sites are a strong contributor to the chemical reactivity of the metal oxide. They can serve as anchor sites to which other chemical groups, and even additional metal oxides, may be attached. And they can affect surface charge, hydrophilicity and biocompatibility.
One way of altering the surface of metal oxides is to attach small chemical groups or electron-withdrawing groups (“EWGs”) in a process known as surface functionalization. The EWG induces polarization of the hydroxide bonds and facilitates dissociation of hydrogen. For example, a stronger EWG should lead to a more polarized bond and therefore a more acidic proton. It will be appreciated that useful EWGs include groups other than hydroxide. The acidity of Lewis sites can be increased by inducing polarization that facilitates the donation of electrons to the site. When compounds so made are placed in water, the acidic protons will dissociate and reduce the aqueous pH measurement.
Though somewhat imprecise when working with solid acid/base systems rather than liquid ones, traditional methods of pH measurement utilizing titrations, pH paper, and pH probes can be used to evaluate the acidity of metal oxides dispersed in aqueous solution. These measurements can be supplemented by the use of techniques including but not limited to colorimetric indicators, infrared spectroscopy, and temperature programmed desorption data to establish the acidified nature of the metal oxide surface. Surface groups can be examined by standard analytical techniques including but not limited to x-ray photoelectron spectroscopy.
Surface functionalization can be accomplished post-synthesis, including, but not limited to, exposing the metal oxide to acidic solutions or to vapors containing the desired functional groups. It can also be accomplished via solid state methods, in which the metal oxide is mixed and/or milled with solids containing the desired functional groups. However, all of these methods require an additional surface functionalization step or steps beyond those required to synthesize the metal oxide itself.
Synthesis and surface functionalization of the AMO material may be accomplished in a “single-pot” hydrothermal synthesis method or its equivalent in which the surface of the metal oxide is functionalized as the metal oxide is being synthesized from appropriate precursors. A precursor salt containing an EWG is solubilized and the resulting solution is acidified using an acid containing a second EWG. This acidified solution is then basified and the basified solution is heated then washed. A drying step produces the solid AMO material.
By way of example, an example AMO form of tin oxide was synthesized and simultaneously surface functionalized using the following single-pot method:
This method results in an AMO of tin, surface-functionalized with chlorine, whose pH is approximately 2 when resuspended and measured in an aqueous solution at 5 wt. % and room temperature. By definition, its Hammet function, H0 is greater than −12. Although an open system such as a flask is described here, a closed system such as an autoclave may also be used.
Utilizing the single pot method disclosed above, a number of AMOs have been synthesized. Table 1 below describes the precursors and acids that have been used, where Ac represents an acetate group with the chemical formula C2H3O2 or CH3COO. In some instances, a dopant is utilized as well.
In some examples, the electron withdrawing groups have a carbon chain length of 6 or less and/or an atomic mass of 200 AMU or less. In some examples, the electron withdrawing groups have a carbon chain length or 8 or less, or 10 or less, and/or an atomic mass of 500 AMU or less.
It will be appreciated that the method's parameters can be varied. These parameters include, but are not limited to, type and concentration of reagents, type and concentration of acid and base, reaction time, temperature and pressure, stir rate and time, number and types of washing steps, time and temperature of drying and calcination, and gas exposure during drying and calcination. Variations may be conducted singly, or in any combination, optionally using experimental design methodologies. Additionally, other metal oxide synthesis methods—e.g., spray pyrolysis methods, vapor phase growth methods, electrodeposition methods, solid state methods, and hydro- or solvo-thermal process methods—may be useful for achieving the same or similar results as the method disclosed here.
A variety of annealing conditions are useful for preparing AMO nanomaterial. Example annealing temperatures may be below 300° C., such as from 100° C. to 300° C. Example annealing time may range from about 1 hours to about 8 hours, or more. Annealing may take place under a variety of atmospheric conditions. For example, annealing may occur in air at atmospheric pressure. Annealing may occur at elevated pressure (greater than atmospheric pressure) or reduced pressure (less than atmospheric pressure or in a vacuum). Annealing may alternatively occur in a controlled atmosphere, such as under an inert gas (e.g., nitrogen, helium, or argon) or in the presence of an oxidizing gas (e.g., oxygen or water).
A variety of drying conditions are useful for preparing AMO nanomaterials. Example drying temperatures may be from 50° C. to 150° C. Example drying time may range from about 0.5 hours to about 8 hours, or more. Drying may take place under a variety of atmospheric conditions. For example, drying may occur in air at atmospheric pressure. Drying may occur at elevated pressure (greater than atmospheric pressure) or reduced pressure (less than atmospheric pressure or in a vacuum). Drying may alternatively occur in a controlled atmosphere, such as under an inert gas (e.g., nitrogen, helium, or argon) or in the presence of an oxidizing gas (e.g., oxygen or water).
The performance characteristics of the AMO nanomaterials differ from those of non-acidified metal oxide nanoparticles. As one example,
As another example,
The AMO material may optionally be represented by the formula MmOx/G, where MmOx is the metal oxide, m being at least 1 and no greater than 5, x being at least 1 and no greater than 21; G is at least one EWG that is not hydroxide; and “/” makes a distinction between the metal oxide and the EWG, denoting no fixed mathematical relationship or ratio between the two. G may represent a single type of EWG, or more than one type of EWG.
Example AMOs are acidified tin oxides (SnxOy), acidified titanium dioxides (TiaOb), acidified iron oxides (FecOd), and acidified zirconium oxide (ZreOf). Example electron-withdrawing groups (“EWGs”) include halogens; Cl, ClO, ClO2, ClO3, ClO4, or hydrogenated forms thereof; Br, BrO, BrO2, BrO3, BrO4, or hydrogenated forms thereof; I or IO3; F; S, SO2, SO3, SO4, or hydrogenated forms thereof; N, NO, NO2, NO3, or hydrogenated forms thereof; PO3, PO4, or hydrogenated forms thereof; BO3 or HBO3; CN, SCN, or OCN; or COO, CH3COO, CO3, HCO3, C2O4, C6H7O7, C2H5CO2, C3H—CO2, or C4H9CO2. Preferred electron-withdrawing groups include Cl, Br, BO3, SO4, PO4, NO3, and CH3COO. Regardless of the specific metal or EWG, according to the present disclosure, the AMO material is acidic but not superacidic, yielding a pH less than 7 when suspended in an aqueous solution at 5 wt. % and a Hammet function, H0 greater than −12, at least on its surface.
The AMO material structure may be crystalline or amorphous (or a combination thereof), and may be utilized singly or as composites in combination with one another, with non-acidified metal oxides, or with other additives, binders, or conductive aids known in the art. In other words, an electrode prepared to take advantage of the AMOs of the present disclosure may or may not comprise other materials. In one example, the AMO may be layered upon a conductive material to form the cathode 104. In some examples, the AMO material is added to a conductive aid material such as graphite, carbon black, or conductive carbon (or their equivalents) in a range of 5 wt. % to 90 wt. %, while the conductive aid and/or a binder material may be present in a range of 10 wt. % to 95%. Optionally, the AMO is added at 10 wt. %, 33 wt. %, 50 wt. %, or 80 wt. %.
To maximize the amount of overall surface area and amount of active sites for reaction of the active material available, the AMO may be present in nanoparticulate form (e.g., less than 1 micron in size) and optionally monodispersed. Optionally, the nanoparticulate size is less than 100 nm and, may be smaller still, such as less than 20 nm or 10 nm. It will be appreciated that nanoparticulate sizes ranging from 1 nm to 100 nm or 1000 nm may be useful with certain AMOs.
Mixed-metal AMOs, in which another metal or metal oxide is present in addition to the simple, or binary oxide, are useful in forming anodes and cathodes for half-cells, electrochemical cells, and batteries. These mixed-metal AMOs may be represented by the formula MmNnOx/G and MmNnRrOx/G, where M is a metal and m is at least 1 and no greater than 5; N is a metal and n is greater than zero and no greater than 5; R is a metal and r is greater than zero and no greater than 5; O is total oxygen associated with all metals and x is at least 1 and no greater than 21; “/” makes a distinction between the metal oxide and an EWG, denoting no fixed mathematical relationship or ratio between the two; and G is at least one EWG that is not hydroxide. G may represent a single type of EWG, or more than one type of EWG.
Some prior art mixed metal oxide systems, of which zeolites are the most prominent example, display strong acidity even though each simple oxide does not. Some examples of the mixed-metal AMO of this disclosure differ from those systems in that the examples disclosed herein include at least one AMO which is acidic (but not superacidic) in simple MmOx/G form. Example mixed metal and metal oxide systems include SnxFecOy+d and SnxTiaOy+b, where y+d and y+b may be an integer or non-integer value.
Optionally, the mixed metal AMO material is produced via the single-pot method with one modification: synthesis begins with two metal precursor salts rather than one, in any proportion. For example, Step 1 of the single-pot method described above may be altered as follows: Initially, 3.8 g of tin (II) chloride dihydrate (SnCl2 2H2O) and 0.2 g of lithium chloride (LiCl) are dissolved in a solution of 20 mL of absolute ethanol and 44 mL distilled water.
Three metal precursor salts, such as shown in Table 1, may optionally be used in any proportion. The metal precursor salts may have the same or differing anionic groups, depending on the desired product. The metal precursor salts may be introduced at different points in the synthesis. The metal precursor salts may be introduced as solids or introduced in a solvent. In some examples, a first metal precursor salt may be used for the primary structure (e.g., larger proportion) of the resultant AMO, and a second (and optionally a third) metal precursor salt may be added as a dopant or as a minor component for the resultant AMO.
Experimentation with the single-pot method led to a variety of useful findings. First, in all cases both surface functionalization and acidity arise endogenously (see
Second, the method is broadly generalizable across a wide range of metal oxides and EWGs. For example, metal oxides of iron, tin, antimony, bismuth, titanium, zirconium, manganese, indium, aluminum, or lithium may be synthesized and simultaneously surface-functionalized with chlorides, sulfates, acetates, nitrates, phosphates, citrates, oxalates, borates, and/or bromides. Mixed metal AMOs may also be synthesized, such as mixed AMOs of tin and iron, tin and manganese, tin and manganese and iron, tin and titanium, indium and tin, antimony and tin, aluminum and tin, lithium and iron, lithium and tin, etc. Additionally, surface functionalization can be accomplished using EWGs that are weaker than halogens and SO4, yet still produce acidic but not superacidic surfaces. For example, the method may be used to synthesize AMOs surface-functionalized with acetate (CH3COO), oxalate (C2O4), and citrate (C6H5O7). A variety of Examples are described below.
Third, there may be a synergistic relationship between the EWG and other properties of the nanoparticles such as size, morphology (e.g., plate-like, spherical-like, needle- or rod-like), oxidation state, and crystallinity (amorphous, crystalline, or a mixture thereof). For example, differences in morphology can occur between AMO nanoparticles synthesized under identical conditions except for the use of a different EWG for surface functionalization, as illustrated in
Fourth, the character of the AMO may be very sensitive to synthesis conditions and procedures. For example, differences in morphology and performance of the AMO nanoparticles can occur when synthesized under identical conditions except for having two different total reaction times. For example,
Fifth, both the anion present in the precursor salt and the anion present in the acid may contribute to the surface functionalization of the AMO. In one example, tin chloride precursors and hydrochloric acid are used in a synthesis of an AMO of tin. The performance of these particles differ from an example in which tin chloride precursors and sulfuric acid are used, or from an example in which tin sulfate precursors and hydrochloric acid are used. Matching the precursor anion and acid anion may be advantageous, for some examples.
Sixth, when utilizing a precursor with a weak EWG and an acid with a strong EWG, or vice versa, the strongly withdrawing anion will dominate the surface functionalization. This opens up a broader range of synthesis possibilities, allowing functionalization with ions that are not readily available in both precursor salts and acids. It may also permit mixed functionalization with both strong and weak EWGs. In one example, a tin acetate precursor and phosphoric acid are used to synthesize an AMO of tin. X-ray photoelectron spectroscopy analysis of the surface shows a greater atomic concentration of phosphorous than of the bonds associated with acetate groups (see
Seventh, while the disclosed method is a general procedure for synthesis of AMOs, the synthesis procedures and conditions may be adjusted to yield sizes, morphologies, oxidation states, and crystalline states as are deemed to be desirable for different applications. As one example, catalytic applications might desire an AMO material which is more active in visible light or one which is more active in ultraviolet light.
In another example, the AMO material may be used as a battery electrode. A primary (single use) battery application might desire an AMO with characteristics that lead to the highest capacity, while a secondary (rechargeable) battery application might desire the same AMO but with characteristics that lead to the highest cyclability.
In
According to the present disclosure, in a complete cell, the anode 106 comprising the disclosed AMO may be utilized with a known electrolyte 108 and a cathode 104 comprising known materials such as lithium cobalt oxide (LiCoO2). The material comprising the separator 110 may likewise be drawn from those currently known in the art.
In a complete cell, the cathode 104 comprising the disclosed AMO may be utilized with a known electrolyte 108 and an anode 106 comprising known materials such as carbon on copper foil, which display less electronegativity than AMOs of the present disclosure. Other anodic materials, such as lithium metal, sodium metal, magnesium metal, or other composite materials containing one or more of these metals, are also useful. In some examples, the anode 106, may consist of or consist essentially of lithium. The material comprising the separator 110 and electrolyte 108 may likewise be drawn from those currently known in the art as discussed above.
Various layering and other enhancement techniques as are known in the art may be deployed to maximize capacity for holding lithium ions for powering the cell 100. It should also be understood that a battery based on an AMO cathode 104 according to the present disclosure can be deployed as a secondary (e.g., rechargeable) battery but can also serve as a primary battery. Although the AMO anodes of the present disclosure lend themselves to a reversible battery chemistry, a cell or battery constructed as described herein, may be satisfactorily deployed as a primary cell or battery.
In some contexts, the word “formation” is used to denote initial charge or discharge of the battery carried out at the manufacturing facility prior to the battery being made available for use. The formation process may be generally quite slow and may require multiple charge-discharge cycles directed at converting the active materials as-manufactured into a form that is more suitable for cell cycling. These conversions may incorporate alterations of the structure, morphology, crystallinity, and/or stoichiometry of the active materials.
In contrast, cells and batteries constructed according to the present disclosure, in some examples, do not require initial formation and therefore are ready to use as primary cells or batteries upon assembly. In other cases, limited or rapid formation may be employed. Moreover, by deploying the cells and batteries of the present disclosure as primary cells that are not intended to be recharged, some of the safety issues that may be inherent with lithium battery chemistry are mitigated, as it is known in the art that the safety issues more frequently arise during battery cycling. However, following an initial primary discharge, cells and batteries disclosed herein are optionally suitable for use as secondary battery systems which may undergo many charge-discharge cycles, such as up to tens, hundreds, or even thousands of cycles.
In some examples, the cathode 104 comprises a mixture or composite of an AMO and a non-acidified metal oxide. Example non-acidified metal oxides include metal oxides that are not acidic, have not been acidified in accordance with the techniques described herein for preparing AMOs described herein, or metal oxides that are not surface functionalized or functionalized in the same way as the AMOs described herein. In some examples, a non-acidified metal oxide in a composite may have a metal or metal oxide composition that is the same or different from an AMO in the composite. As example, an AMO in a composite may comprise acidified metal oxide of tin, titanium, iron, zirconium, or various combination of these, and a non-acidified metal oxide in a composite may comprise an oxide of tin, titanium, iron, zirconium, lithium, nickel, manganese, cobalt, aluminum, or various combinations of these. Known electrolytes 108, anodes 106, and separators 110, or those otherwise described in this disclosure may be utilized with such examples.
It will be appreciated that various battery constructions are possible using the AMO materials disclosed herein. For example, a battery may comprise a first electrode comprising an AMO nanomaterial, a second electrode, and an electrolyte positioned between the first electrode and the second electrode. As an example in a lithium-ion battery, the first electrode may operate as a cathode or an anode. For example, in operation as a cathode, the second electrode may correspond to lithium metal, graphite, or another anodic material. As another example, in operation as an anode, the second electrode may correspond to a LiCoO2, LiMn2O4, LiNiO2, or another cathodic material. Useful materials for the second electrode include, but are not limited to, graphite, lithium metal, sodium metal, lithium cobalt oxide, lithium titanate, lithium manganese oxide, lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate, lithium nickel cobalt aluminum oxide (NCA), or any combination of these.
It will be appreciated that the AMO materials disclosed herein may also be added as dopants to conventional lithium-ion cell anodes and/or cathodes, such as in amounts between 0.01 wt. % and 20 wt. %, or for example, an amount of about 1 wt. %, 2 wt. %, 3 wt. %, 4 wt. %, 5 wt. %, 6 wt. %, 7 wt. %, 8 wt. %, 9 wt. %, 10 wt. %, 11 wt. %, 12 wt. %, 13 wt. %, 14 wt. %, 15 wt. %, 16 wt. %, 17 wt. %, 18 wt. %, 19 wt. %, or 20 wt. % of AMO material in an electrode. The disclosed AMO materials may provide for or enhance a capacity for storing lithium atoms and by adding these materials to conventional lithium-ion cell electrodes, the ability of these composites to be useful electrode materials is markedly improved. As one specific example, an electrode comprises LiCoO2 and an AMO. As another example, an electrode comprises a carbonaceous material, such as graphite, and an AMO.
Advantageously, the AMO material may optionally be used with an acidic component, such as a binder, an acidic electrolyte, or an acidic electrolyte additive. This may be in the context of an anode, cathode, half-cell, complete cell, integrated battery, or other components. The inventors have surprisingly found that including acidic components and/or acidic species, such as organic acids or organic acid anhydrides, in a battery comprising an AMO material results in an increase in the capacity versus batteries where the acidic species are not included. Again, the prior art teaches against use of acidic species, as these species may degrade metal current collectors and housings and cause deterioration in other electrode components. However, it may be desirable for some embodiments to not utilize an acidic component.
As shown in
At the present time, lithium batteries are perceived to be a safety risk in certain situations. For example, airline regulations currently require partial discharge of lithium batteries in order to be carried in the cargo hold. Fires have been reported in devices utilizing lithium batteries, resulting from runaway exothermal reactions. Moreover, lithium fires can be difficult to extinguish with popularly deployed fire suppression systems and devices. For these reasons, lithium containing compounds rather than metallic lithium are used in many commercial battery cells.
Use of lithium containing compounds in an anode, rather than lithium metal, may, however, limit the amount of lithium available for reaction and incorporation into the cathode upon discharge, and may thus also limit the capacity of such cells. The presently disclosed AMO materials, however, show not only large uptake of lithium during discharge but also enhanced safety characteristics. For example, when battery cells comprising the AMO material in a cathode and a lithium metal electrode are subjected to safety tests, such as nail penetration tests, shorting tests, and overvoltage tests, the cells perform well and do not appear to pose an unacceptable risk of fire or explosion.
Several cells were constructed with a cathode comprising a SnO2 AMO and an anode comprising a conductive carbon black (Ketjenblack), polyvinylidene fluoride (PVDF), and polyaryl amide (PAA) at a ratio of 63/10/26.1/0.9, by volume. Double-sided layers of this composition were prepared at 4 mg/cm2 per side. Six of these layers made up the cathode. The size of the prepared cathode was 9 cm×4 cm. A 25 μm thick layer of polypropylene was obtained from Targray Technology International, Inc., and used as a separator. The separator size was 9.4 cm×4.4 cm. An electrolyte was prepared from 1 M LiPF6 in a solvent of ethylene carbonate (EC), diethyl carbonate (DEC), and dimethylcarbonate (DMC) in a 1:1:1 ratio, by volume. The anode was a 50 μm thick layer of lithium metal with dimensions of 9.2 cm×4.2 cm.
Two of the constructed cells were discharged prior to a safety test and found to have an actual capacity of 1.7 Ah and a specific capacity of 1575 mAh/g SnO2.
Embodiments of constructed electrochemical cells incorporating AMO material as a cathode and lithium as an electrode have been tested to successfully undergo up to 900 or more charge-discharge cycles without resulting in catastrophic and destructive failure. Stated another way, embodiments of constructed electrochemical cells incorporating AMO material as a cathode and lithium as an electrode have been tested to successfully undergo up to 900 or more charge-discharge cycles and still hold a charge and maintain useful capacity.
Without wishing to be bound by any theory, the enhanced safety provided by use of AMO-based cathode materials in lithium cells may arise from the ability of the AMO material to passivate the lithium metal and prevent dendrite formation. The inventors have observed that, upon cycling, the lithium metal anode did not appear to grow or otherwise form dendrites, but the lithium anode took on a softer and less crystalline appearing structure. In some embodiments, a lithium anode may be passivated, such as by cycling as a component of an electrochemical cell as described herein, and then removed from the electrochemical cell and used as an electrode in a new electrochemical cell with a different cathode. Additionally, cells constructed according to the present disclosure make use of low operating voltages, such as between 1 and 2 volts, which contrasts with the typical voltage of a lithium or lithium-ion battery cell, which operate commonly around 3-4.2 volts. Such a difference in operational voltage may, in part, account for the safety of the disclosed cells.
Referring now to
To form a carbon/SnO2 electrode layer 1806, a mixture of AMO SnO2, Ketjenblack, and PVDF, each 33.3% by weight, was prepared and a slurry was formed by adding NMP solvent. The slurry was coated on part of the Ketjenblack coated copper foil (1802, 1804). The resultant tape was dried in a vacuum oven at 100° C. (overnight) and calendared at room temperatures. The thickness of the tape was measured using a micrometer at the SnO2/Ketjenblack coated area and the Ketjenblack only coated area. The thickness of the Ketjenblack layer 1704 was found to be about 8 μm, while the SnO2 AMO-containing layer 1806 was found to be about 2 μm thick. The foil layer was about 10 μm thick, providing a total thickness of the cathode 1800 of about 18-20 μm.
The calendared tape was punched out into circular disks from the Ketjenblack only coated area and the SnO2/Ketjenblack coated area. The mass of the Ketjenblack only coated disc was subtracted from the SnO2/Ketjenblack coated disc to obtain the total mass of the electrode layer. In the case of one tested cell type, the total mass of the electrode material is 0.0005 g (after subtracting the equivalent of the Ketjenblack only coated disc mass), providing a total active material (SnO2) mass of about 0.000167 g (33.3% of total mass).
Useful aspects of the cathode 1800 include the layering of carbonaceous layer and the AMO-containing layer, the use of Ketjenblack high surface area conductive carbon in both layers, a 33% active material content in the AMO-containing layer, the thickness of the AMO-containing layer, the use of PVDF as a binder, and the use of copper foil as a current collector. Each of these aspects may optionally be varied.
For example, carbons other than Ketjenblack may be used. It will be appreciated that the AMO materials used as the active material may possess very small particle dimensions, such as on the order of 1-100 nm (e.g., 2-5 nm), with a narrow size distribution range. Although graphite may be useful as a carbon for cathodes of the present disclosure, Ketjenblack has a particle size much closer to the AMO particle size than does commercially available graphite, as well as some other conductive carbons. Ketjenblack particles may be, for example, about 30-300 nm in size, with a wider distribution than the AMO particles. In contrast, graphite particles tend to have a much larger size, such as on the order of 100 μm. Such close similarity in size may allow the mixture of Ketjenblack and AMO to have more uniformity on a local scale and allow more complete or better mixing and contact between the particles of carbon and particles of AMO.
As another example, the number of layers of the carbonaceous material layers and AMO-containing layers may be varied for forming the electrode. In the example described above, the electrode comprises one carbonaceous material layer and one AMO-containing layer. Optionally, additional carbonaceous material layers may be included. Optionally, additional AMO-containing layers may be included. Advantageously, a carbonaceous material layer may be placed directly on an AMO-containing layer, followed by another carbonaceous material layer, followed by another AMO-containing layer, etc. Examples are contemplated where any number of pairs of layers may be included in an electrode, such as 1-20 layer pairs. In addition, an acidic species may optionally be incorporated into the electrode and/or an electrode layer, as described above, and may be mixed with the carbonaceous material, the AMO, and/or the binder.
In some embodiments, however, distinct layers are not used in an AMO-containing electrode and the electrode may comprise the AMO, the carbonaceous material, and one or more binders (e.g., PVDF, PAA, etc.) in a single, mixed structure, with a similar composition as the overall structure of the layered electrodes described above. For example, an electrode may comprise separate carbonaceous layers (0% AMO) and AMO-containing layers (e.g., 33% AMO) to provide an overall composition having about 21% AMO. Alternatively, an electrode may comprise a single structure containing a 21% AMO mixture with carbonaceous materials (and binders). Optionally, the single mixed electrode structure may optionally be assembled as multiple layers, with each layer having a common composition of the mixed structure.
As another example, the percentage of active material may be varied. For example, in the above-described multi-layer electrode, the carbonaceous layers included no AMO, while the AMO-containing layers contained about 33%. When taken as a whole, such a composition of layers may amount to about 21% AMO overall, by weight. However, the AMO-containing layers and/or the electrode as a whole may include between 1% and 90% AMO, by weight, depending on the configuration. In some embodiments, a high AMO fraction may be useful, such as an amount of AMO of 50% by weight, or more.
In other embodiments, a low AMO fraction may be useful, such as an amount of AMO of 35% by weight, or less. Contrary to conventional thinking, where the amount of active material in an electrode is typically kept high (e.g., 80% or greater, by weight) to allow for maximum capacity and specific capacity of a cell incorporating the electrode, the inventors have found that lower active material (AMO) loading advantageously allows for creation of batteries with higher overall capacity and higher specific capacities. Without wishing to be bound by any theory, the high capacity of the disclosed cells incorporating AMO materials may be achieved by the particular affinity of the AMO material for lithium atoms. The incredible amount of lithium atoms that can be stored by electrodes incorporating the AMO materials may result in needing extra space in order to accommodate the uptaken lithium. By including lower fractions of active material, additional space for the lithium atoms may be achieved. In fact, fractions of AMO active material in an electrode overall or an electrode containing layer as low as 15% or 20% may exhibit even higher capacities and specific capacities than electrodes with considerably more AMO active material loading. In addition, the conductive carbon may be activated by the presence of the AMO material and may provide or enable additional active sites for uptake of lithium during charging and/or discharging. It will be appreciated that low active material loading of this nature may not be desirable for all embodiments.
Due to its incredible affinity for lithium atoms, in some embodiments, the AMO may be added to a conventional lithium cell electrode or lithium-ion electrode. In this way, conventional electrodes can have their lithiation capacity advantageously improved while altering the electrochemistry of the cell little or not at all. In some examples, AMOs may be added to conventional lithium cell electrodes or lithium-ion electrode in amounts of up to 5%.
As another example, the thicknesses of the layers of an electrode comprising an AMO may be varied, such as to improve performance or to modify other properties of the electrode, such as an active material loading (e.g., weight percent AMO). As examples, the thickness of carbonaceous layers of an electrode may be from 0.5 μm to 50 μm, from 1.0 μm to 20 μm, or from 1.5 μm to 10 μm. As other examples, the thickness of AMO-containing layers of an electrode may be from 0.1 μm to 20 μm, from 1 μm to 15 μm, or from 5 μm to 10 μm. Values outside these ranges for a thickness of the electrode or an electrode may optionally be used, such as electrodes having thicknesses of up to 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, or 50 μm, for example. However, the inventors have found that, for some embodiments, as described above, distinct carbonaceous and AMO-containing layers are not needed, and that the electrode may optionally comprise a single or multiple AMO-containing layers or structures.
As another example, the amount and type of binder included in the electrode may be varied to achieve particular results. In some embodiments, large amounts of binder may be included in an electrode or an electrode layer. For example, the binder may be present in an electrode or an electrode layer at 10% to 50%, by weight, or in a similar amount as the carbonaceous material. The inventors have found that inclusion of a high or comparable amount of binder as the conductive carbon may be advantageous for forming good quality electrodes having useful structural and capacity characteristics. In some embodiments, the conductive carbon may have difficulty in forming a compacted structure on its own, and by including substantial amounts of binder, the ability to form useful carbonaceous and AMO-containing layers and/or electrodes may be improved. However, it will be appreciated that relatively large amounts of binder may not be desirable in all embodiments.
As another example, a variety of current collector configurations may be used. As described above, a copper film current collector may be used. Other metals may alternatively be used, including aluminum, stainless steel, brass, titanium, etc. In addition, multiple current collectors may be used, such as in a configuration where the AMO-containing layers and/or carbonaceous layers may be positioned between the multiple current collectors. It will be appreciated that different current collectors may be used at the anode and the cathode. In addition, the current collector need not comprise a film, and may alternatively be constructed as a mesh, grid, pin, or other structure having any suitable thickness or dimensions. Current collectors may also be useful for temperature control, in some embodiments, and may serve as a heat sink or heat carrier for removal of excess thermal energy from the active material of a cell.
A coin-cell type battery cell was constructed and tested by repeated discharge-charge cycles. The cathode containing a SnO2 AMO was assembled as described above using a glass separator, an electrolyte of 1 M LiPF6 in 1:1:1 DEC/EC/DMC by volume, and a lithium metal anode. The cell was discharged from its as assembled open circuit voltage of 3.19 V to 0.01 V at a rate of C/10. The cell was then charged from 0.01 V to 1.5 V at a rate of C/10. After this the cell was repeatedly cycled from 1.5 V to 0.01 V and from 0.01 V to 1.5 V at a rate of C/5. While the voltages and charging rates here are merely examples, it will be appreciated that other charging and discharging rates may be used and that other charging and discharging voltages may be used. The cell was cycled for at least 111 charge-discharge cycles and the discharge capacity (mAh/g SnO2 AMO) tabulated. Table 2, below, shows the discharge and charge capacities for each cycle.
It should also be appreciated that the initial discharge occurs from the open circuit voltage of about 3.2 volts to about 0.01 V, while the cycling of charging and discharging takes place between 0.01 V and 1.5 V. Optionally, cycling of charging and discharging may take place at higher upper limits, such as 2.0 V, 2.5 V, 3.0 V, or 3.2 V, for example. By cycling at higher upper voltage limits, although still below the as-assembled open circuit voltage, an amount of the capacity identified above as irreversible may be retained as reversible capacity.
The unusual capacities also posit a novel “hybrid” battery system featuring a very long first discharge cycle utilizing the high initial lithiation capacity, followed by shorter, but reversible, cycling at the lower delithiation capacity. There is no such system currently in the marketplace.
The capacities as revealed by testing roughly translate to an energy density of 12,584 Whr/kg SnO2, depending on the voltage range selected for cycling. This is an energy density comparable to that of gasoline (12,889 Whr/kg) and is, to the inventor's knowledge, the highest energy density achieved in any battery material to date.
Again, without wishing to be bound by any theory, the inventor believes that the structure of the disclosed cells having a lithium metal anode and a cathode comprising an AMO material with incredible lithiation capacity allow for such high capacities due, in part, to the low levels of active material (AMO) in the cathode, such as between 10% and 30%, by weight. The low active material loading may provide sufficient space for the large amount of lithium atoms to be taken up and stored in the cathode during discharge. A loading of about 20-25% may represent a transition point where lower loadings do not provide sufficient active material or sufficient active sites for reaction and uptake of lithium atoms, while higher loadings may not provide suitable volume for lithium atoms to be taken up.
The specific energy densities of the disclosed AMO-based electrochemical cells described herein are novel and taught to be impossible by the scientific literature. Such results may be possible here because they proceed by a novel mechanism outside of those currently taught or understood by those of skill in the art, leading to the potential that even higher capacities than those disclosed herein can be achieved. The new availability of such energy density may inevitably lead to other electrodes and batteries, which may embody such things as unusual shapes and sizes, new electrolyte systems, separators, and current collectors. The disclosed and claimed electrodes, cells, and batteries should not be seen as limited to the ancillary components that are presently available in the open marketplace or disclosed herein or in the literature. Instead, it will be appreciated that the disclosed and claimed electrodes, cells, and batteries may take on any suitable shape, size, or configuration, incorporate any suitable electrolyte, current collector, or separator, and employ any suitable discharge and/or charge profile.
The invention may be further understood by reference to the following non-limiting examples, which describe formation of an electrode for an electrochemical cell including a first electrode comprising a metal oxide (e.g., an AMO) and a second electrode including metallic lithium. The first electrode was constructed to include 80 weight percent of the metal oxide, consistent with conventional practice for forming electrochemical cells in the battery industry. As described above, the capacities for such electrochemical cells may be significantly improved by reducing the amount of metal oxide in the first electrode to an amount less than 80 percent by weight, such as 5-15%, 20-35%, or 55-70%, though such amounts may not be desired to use in all embodiments. The following examples are illustrative only and are not intended to be limiting.
A tin oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, tin acetate (Sn(CH3COO)2) was dissolved in an ethanol/water solution and acidified by addition of hydrochloric acid (HCl). The resultant AMO nanomaterial was a soft, grey material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A tin oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, tin acetate (Sn(CH3COO)2) was dissolved in an ethanol/water solution and acidified by addition of sulfuric acid (H2SO4). The resultant AMO nanomaterial was a grey, flaky material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A tin oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, tin acetate (Sn(CH3COO)2) was dissolved in an ethanol/water solution and acidified by addition of nitric acid (HNO3). The resultant AMO nanomaterial was a grey, flaky material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A tin oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, tin acetate (Sn(CH3COO)2) was dissolved in an ethanol/water solution and acidified by addition of phosphoric acid (H3PO4). The resultant AMO nanomaterial was a brown, soft, flaky material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A tin oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, tin acetate (Sn(CH3COO)2) was dissolved in an ethanol/water solution and acidified by addition of citric acid (C6H8O7). The resultant AMO nanomaterial was a brown, flaky material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A tin oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, tin acetate (Sn(CH3COO)2) was dissolved in an ethanol/water solution and acidified by addition of oxalic acid (C2H2O4). The resultant AMO nanomaterial was a taupe, flaky material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A doped tin oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, tin acetate (Sn(CH3COO)2) was dissolved in an ethanol/water solution with a lesser amount of iron acetate. The solution was acidified by addition of hydrochloric acid (HCl). The resultant AMO nanomaterial was a soft and flaky, creamy grey material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A doped tin oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, tin acetate (Sn(CH3COO)2) was dissolved in an ethanol/water solution with a lesser amount of iron acetate. The solution was acidified by addition of sulfuric acid (H2SO4). The resultant AMO nanomaterial was a pale, taupe colored, soft, flaky material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
Two doped tin oxide AMO samples were synthesized using a single-pot hydrothermal synthesis method. Briefly, tin acetate (Sn(CH3COO)2) was dissolved in an ethanol/water solution with a lesser amount of iron acetate (Fe(CH3COO)3). The solution was acidified by addition of nitric acid (HNO3). The resultant AMO nanomaterial was a soft, white material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A doped tin oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, tin acetate (Sn(CH3COO)2) was dissolved in an ethanol/water solution with a lesser amount of iron acetate (Fe(CH3COO)3). The solution was acidified by addition of oxalic acid (C2H2O4). The resultant AMO nanomaterial was a soft, white material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A doped tin oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, tin acetate (Sn(CH3COO)2) was dissolved in an ethanol/water solution with a lesser amount of iron acetate (Fe(CH3COO)3). The solution was acidified by addition of phosphoric acid (H3PO4). The resultant AMO nanomaterial was a white, flaky material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A doped tin oxide was synthesized using a single-pot hydrothermal synthesis method. Briefly, tin acetate (Sn(CH3COO)2) was dissolved in an ethanol/water solution with a lesser amount of iron acetate (Fe(CH3COO)3). The solution was acidified by addition of citric acid (C6H8O7). The resultant material did not form particles, and was a yellow, glassy hard material, which was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A tin oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, tin acetate (Sn(CH3COO)2) was dissolved in an ethanol/water solution and acidified by addition of hydrobromic acid (HBr). The resultant AMO nanomaterial was a grey, soft, powdery material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A tin oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, tin acetate (Sn(CH3COO)2) was dissolved in an ethanol/water solution and acidified by addition of boric acid (H3BO3). The resultant AMO nanomaterial was a grey, flaky material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A doped tin oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, tin sulfate (SnSO4) was dissolved in an ethanol/water solution with a lesser amount of manganese chloride (MnCl2). The solution was acidified by addition of sulfuric acid (H2SO4). The resultant AMO nanomaterial was a very soft, tan material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A doped tin oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, tin chloride (SnCl2) was dissolved in an ethanol/water solution with a lesser amount of manganese chloride (MnCl2). The solution was acidified by addition of hydrochloric acid (HCl). The resultant AMO nanomaterial was a soft, greyish brown material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
Two doped tin oxide AMO samples were synthesized using a single-pot hydrothermal synthesis method. Briefly, tin chloride (SnCl2) was dissolved in an ethanol/water solution with lesser amounts of both iron chloride (FeCl3) and aluminum chloride (AlCl3). The solution was acidified by addition of hydrochloric acid (HCl). The resultant AMO nanomaterial for the first sample was a light tan, flaky material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A doped iron oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, iron chloride (FeCl3) was dissolved in an ethanol/water solution with a lesser amount of tin chloride (SnCl2). The ratio of iron to tin was 95:5. The solution was acidified by addition of hydrochloric acid (HCl). The resultant AMO nanomaterial was a soft, red material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A doped iron oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, iron chloride (FeCl3) was dissolved in an ethanol/water solution with a lesser amount of tin chloride (SnCl2). The ratio of iron to tin was 95:5. The solution was acidified by addition of hydrochloric acid (HCl). The resultant AMO nanomaterial was a black, glassy material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
An iron oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, iron nitrate Fe(NO3)3 was dissolved in an ethanol/water solution and acidified by addition of nitric acid (HNO3). The resultant AMO nanomaterial was a black, glassy material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A bismuth oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, bismuth chloride (BiCl3) was dissolved in an ethanol/water solution and acidified by addition of hydrochloric acid (HCl). The resultant AMO nanomaterial was a soft, white material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A zirconium oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, zirconium sulfate (Zr(SO4)2) was dissolved in an ethanol/water solution and acidified by addition of sulfuric acid (H2SO4). The resultant AMO nanomaterial was a flaky, white material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A titanium oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, titanium oxysulfate (TiOSO4) was dissolved in an ethanol/water solution and acidified by addition of sulfuric acid (H2SO4). The resultant AMO nanomaterial was a white, flaky material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
An antimony oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, antimony sulfate (Sb2(SO4)3) was dissolved in an ethanol/water solution and acidified by addition of sulfuric acid (H2SO4). The resultant AMO nanomaterial was a very soft, white material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
An indium oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, indium chloride (InCl3) was dissolved in an ethanol/water solution and acidified by addition of hydrochloric acid (HCl). The resultant AMO nanomaterial was a white material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
An indium oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, indium sulfate (In2(SO4)3) was dissolved in an ethanol/water solution and acidified by addition of sulfuric acid (H2SO4). The resultant AMO nanomaterial was a white material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
An indium oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, indium bromide (InBr3) was dissolved in an ethanol/water solution and acidified by addition of hydrobromic acid (HBr). The resultant AMO nanomaterial was a blue-white material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
An indium oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, indium chloride (InCl3) was dissolved in an ethanol/water solution and acidified by addition of hydrochloric acid (HCl). The resultant AMO nanomaterial was grey with a yellow ring and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A doped mixed lithium oxide and iron oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, lithium acetate (Li(CH3COO)) and iron chloride (FeCl3) were dissolved in an ethanol/water solution with a lesser amount of tin chloride (SnCl2). The solution was acidified by addition of hydrochloric acid (HCl). During synthesis, a tan, pinkish color with a green ring on the flask developed. The final AMO nanomaterial, however, was grey and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A doped mixed lithium oxide and iron oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, lithium acetate (Li(CH3COO)) and iron chloride (FeCl3) were dissolved in an ethanol/water solution with a lesser amount of tin chloride (SnCl2). The solution was acidified by addition of hydrochloric acid (HCl). The resultant AMO nanomaterial was a golden pale material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
A doped mixed lithium oxide and iron oxide AMO was synthesized using a single-pot hydrothermal synthesis method. Briefly, lithium acetate (Li(CH3COO)) and iron chloride (FeCl3) were dissolved in an ethanol/water solution with a lesser amount of tin chloride (SnCl2). The solution was acidified by addition of hydrochloric acid (HCl). The resultant AMO nanomaterial was a light creamy white material and was formed into an electrode. The electrode was assembled in a battery cell against lithium metal and cycled by discharging to zero volts, followed by charging to 1.5 volts.
All references throughout this application, for example patent documents, including issued or granted patents or equivalents and patent application publications, and non-patent literature documents or other source material are hereby incorporated by reference herein in their entireties, as though individually incorporated by reference.
All patents and publications mentioned in the specification are indicative of the levels of skill of those skilled in the art to which the invention pertains. References cited herein are incorporated by reference herein in their entirety to indicate the state of the art, in some cases as of their filing date, and it is intended that this information can be employed herein, if needed, to exclude (for example, to disclaim) specific embodiments that are in the prior art.
When a group of substituents is disclosed herein, it is understood that all individual members of those groups and all subgroups and classes that can be formed using the substituents are disclosed separately. When a Markush group or other grouping is used herein, all individual members of the group and all combinations and subcombinations possible of the group are intended to be individually included in the disclosure. As used herein, “and/or” means that one, all, or any combination of items in a list separated by “and/or” are included in the list; for example “1, 2 and/or 3” is equivalent to “1, 2, 3, 1 and 2, 1 and 3, 2 and 3, or 1, 2, and 3”.
Every formulation or combination of components described or exemplified can be used to practice the invention, unless otherwise stated. Specific names of materials are intended to be exemplary, as it is known that one of ordinary skill in the art can name the same material differently. It will be appreciated that methods, device elements, starting materials, and synthetic methods other than those specifically exemplified can be employed in the practice of the invention without resort to undue experimentation. All art-known functional equivalents, of any such methods, device elements, starting materials, and synthetic methods are intended to be included in this invention. Whenever a range is given in the specification, for example, a temperature range, a time range, or a composition range, all intermediate ranges and subranges, as well as all individual values included in the ranges given are intended to be included in the disclosure.
As used herein, “comprising” is synonymous with “including,” “containing,” or “characterized by,” and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. As used herein, “consisting of” excludes any element, step, or ingredient not specified in the claim element. As used herein, “consisting essentially of” does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim. Any recitation herein of the term “comprising”, particularly in a description of components of a composition, in a description of a method, or in a description of elements of a device, is understood to encompass those compositions, methods, or devices consisting essentially of and consisting of the recited components or elements, optionally in addition to other components or elements. The invention illustratively described herein suitably may be practiced in the absence of any element, elements, limitation, or limitations which is not specifically disclosed herein.
The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.
This application is a continuation-in-part of U.S. application Ser. No. 17/220,637, filed on Apr. 1, 2021, now U.S. Pat. No. 11,962,004, which is a continuation of U.S. application Ser. No. 15/728,299, filed on Oct. 9, 2017, now U.S. Pat. No. 10,978,704, which is a continuation of U.S. application Ser. No. 15/352,388, filed on Nov. 15, 2016, now U.S. Pat. No. 9,786,910, which claims the benefit of and priority to U.S. Provisional Application No. 62/256,065, filed on Nov. 16, 2015, and U.S. Provisional Application No. 62/256,059, filed on Nov. 16, 2015. This application is also a continuation-in-part of U.S. application Ser. No. 17/717,931, filed on Apr. 11, 2022, which is a continuation of U.S. application Ser. No. 16/780,583, filed on Feb. 3, 2020, now U.S. Pat. No. 11,302,912, which is a divisional of U.S. application Ser. No. 15/949,805, filed on Apr. 10, 2018, now U.S. Pat. No. 10,553,861, which claims the benefit of and priority to U.S. Provisional Application No. 62/483,789, filed on Apr. 10, 2017, U.S. Provisional Application No. 62/507,655, filed on May 17, 2017, and U.S. Provisional Application No. 62/507,660, filed on May 17, 2017. This application is also a continuation-in-part of U.S. application Ser. No. 18/310,351, filed on May 1, 2023, which is a continuation of U.S. application Ser. No. 15/982,776, filed on May 17, 2018, now U.S. Pat. No. 11,641,014, which claims the benefit of and priority to U.S. Provisional Application No. 62/507,658, filed on May 17, 2017. This application is also a continuation-in-part of U.S. application Ser. No. 18/168,397, filed on Feb. 13, 2023, which is a continuation of U.S. application Ser. No. 16/792,409, filed on Feb. 17, 2020, now U.S. Pat. No. 11,581,536, which is a divisional of U.S. application Ser. No. 15/981,350, filed on May 16, 2018, now U.S. Pat. No. 10,566,620, which claims the benefit of and priority to U.S. Provisional Application No. 62/507,659, filed on May 17, 2017. This application is also a continuation-in-part of U.S. application Ser. No. 16/603,775, filed on Oct. 8, 2019, which is U.S. National Stage Application of PCT Application No. PCT/US2018/026961, filed on Apr. 10, 2018, which claims the benefit of and priority to U.S. Provisional Application No. 62/483,789, filed on Apr. 10, 2017, U.S. Provisional Application No. 62/507,655, filed on May 17, 2017, U.S. Provisional Application No. 62/507,658, filed on May 17, 2017, U.S. Provisional Application No. 62/507,659, filed on May 17, 2017, U.S. Provisional Application No. 62/507,660, filed on May 17, 2017, U.S. Provisional Application No. 62/507,662, filed on May 17, 2017, and U.S. Provisional Application No. 62/651,002, filed on Mar. 30, 2018. This application is also a continuation-in-part of U.S. application Ser. No. 17/596,561, filed on Dec. 13, 2021, which is a U.S. National Stage Application of PCT Application No. PCT/US2020/037597, filed on Jun. 12, 2020, which claims the benefit of and priority to U.S. Provisional Application No. 62/860,616, filed on Jun. 12, 2019. Each of the foregoing patents and applications are hereby incorporated by reference in their entireties for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 62256065 | Nov 2015 | US | |
| 62256059 | Nov 2015 | US | |
| 62483789 | Apr 2017 | US | |
| 62507655 | May 2017 | US | |
| 62507660 | May 2017 | US | |
| 62507658 | May 2017 | US | |
| 62507659 | May 2017 | US | |
| 62483789 | Apr 2017 | US | |
| 62507655 | May 2017 | US | |
| 62507658 | May 2017 | US | |
| 62507659 | May 2017 | US | |
| 62507660 | May 2017 | US | |
| 62507662 | May 2017 | US | |
| 62651002 | Mar 2018 | US | |
| 62860616 | Jun 2019 | US |
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| Parent | 15949805 | Apr 2018 | US |
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| Child | 16792409 | US |
| Number | Date | Country | |
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| Parent | 15728299 | Oct 2017 | US |
| Child | 17220637 | US | |
| Parent | 15352388 | Nov 2016 | US |
| Child | 15728299 | US | |
| Parent | 16780583 | Feb 2020 | US |
| Child | 17717931 | US | |
| Parent | 15982776 | May 2018 | US |
| Child | 18310351 | US | |
| Parent | 16792409 | Feb 2020 | US |
| Child | 18168397 | US |
| Number | Date | Country | |
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| Parent | 17220637 | Apr 2021 | US |
| Child | 18635852 | US | |
| Parent | 17717931 | Apr 2022 | US |
| Child | 18635852 | US | |
| Parent | 18310351 | May 2023 | US |
| Child | 18635852 | US | |
| Parent | 18168397 | Feb 2023 | US |
| Child | 18635852 | US | |
| Parent | 16603775 | Oct 2019 | US |
| Child | 18635852 | US | |
| Parent | 17596561 | Dec 2021 | US |
| Child | 18635852 | US |
