Patent Application
20240429439
The present disclosure relates generally to solid-state structures, and more particularly, to solid-state ion-conducting structures formed within and/or comprising volatile sintering aids.
Solid-state electrolytes (SSEs) formed by ion-conducting ceramics have been contemplated for use in next generation lithium (Li) ion battery technologies, for example, to provide enhanced safety and higher energy densities. To this end, a range of ceramic SSEs have been developed, such as but not limited to perovskite-type Li3xLa2/3−xTiO3, NASICON-type Li1.3Al0.3Ti1.7(PO4)3 and Li1+xAlxGe2−x(PO4)3, garnet-type Li7La3Zr2O12 (LLZO) and their derivatives. Such ceramic SSEs can exhibit high ionic conductivity (e.g., up to 10−3 S/cm), a wide electrochemical window (e.g., up to 6 V), good chemical stability (e.g., against Li metal), and excellent mechanical properties (e.g., mechanical strength up to 20 GPa). However, the adoption of SSEs for all-solid-state batteries has been hindered due to fabrication issues. For example, the presence of voids, gaps, pinholes, or other defects in the SSEs after sintering can make the sintered SSEs vulnerable to penetration by Li dendrites, leading to thermal runaway, fire, or even explosion. This vulnerability can be particularly problematical when operating battery cells at medium-to-high current densities and/or over long durations. Previous efforts have attempted to address these fabrication issues by relying on inorganic filters or sintering aids. However, the prolonged heating at high temperatures required by conventional sintering techniques results in the decomposition, melting, and/or sublimination of many promising fillers or sintering aids, thereby limiting the class of available materials and performance of the sintered structures. Embodiments of the disclosed subject matter may address one or more of the above-noted problems and disadvantages, among other things.
Embodiments of the disclosed subject matter system provide sintering methods that can be used to form solid-state ion-conducting structures with sintering aids or fillers, as well as solid-state ion-conducting structures incorporating such sintering aids or fillers. In some embodiments, the sintering aid or filler is volatile (e.g., having a melting point less than a temperature at which a base material or matrix of the ion-conducting structure is sintered, for example, a melting point less than 1200 K), but has a high ionic conductivity (e.g., ≥10−6 S/cm, for example, ≥10−4 S/cm) and a low electronic conductivity (e.g., ≤10−10 S/cm, for example, ≤10−11 S/cm). For example, in some embodiments, the solid-state ion-conducting structure can be formed and used as a solid-state electrolyte (SSE) in a battery. In some embodiments, the solid-state ion-conducting structure exhibits a higher relative density (e.g., >93%), a higher ionic conductivity, and/or a lower electronic conductivity as compared to conventionally-sintered structures and/or pristine material without any sintering aid or filler.
In one or more embodiments, a solid-state ion-conducting structure can comprise a plurality of grains formed of a first material composition. The solid-state ion-conducting structure can further comprise a second material composition different from the first material composition. The second material composition can wet boundaries of the plurality of grains and/or fill voids between adjacent grains. Each of the first and second material compositions can have an ionic conductivity greater than or equal to approximately 1×10−4 S/cm. A melting point of the first material composition can be greater than or equal to a first temperature, and a melting point of the second material composition can be less than the first temperature.
In one or more embodiments, a battery can comprise an anode, a cathode, and a solid-state electrolyte separating the anode from the cathode. The solid-state electrolyte can comprise a plurality of grains formed of a first material composition. The solid-state electrolyte can further comprise a second material composition different from the first material composition. The second material composition can wet boundaries of the plurality of grains and/or fill voids between adjacent grains. Each of the first and second material compositions can have an ionic conductivity greater than or equal to approximately 1×10−4 S/cm. A melting point of the first material composition can be greater than or equal to a first temperature, and a melting point of the second material composition can be less than the first temperature.
In one or more embodiments, a method can comprise providing a first powder. The first powder can comprise a first material composition or one or more first precursors of the first material composition. A melting point of the first material composition can be greater than or equal to a first temperature. The method can further comprise providing a second powder. The second powder can comprise a second material composition or one or more second precursors of the second material composition. The second material composition can be different from the first material composition. A melting point of the second material composition can be less than the first temperature. The method can also comprise forming a composite pellet by at least mixing the first and second powders together. The method can further comprise subjecting the composite pellet to a high-temperature heating pulse so as to convert the composite pellet into a solid-state ion-conducting structure. The high-temperature heating pulse can comprise exposure to a first sintering temperature of at least 600 K for a duration less than or equal to 60 seconds. Within the solid-state ion-conducting structure, the second material composition can wet boundaries of a plurality of grains formed by the first material composition and/or fill voids between adjacent grains formed by the first material composition. Each of the first and second material compositions can have an ionic conductivity greater than or equal to approximately 1×10−4 S/cm.
In one or more embodiments, a method can comprise providing an initial pellet, which can comprise a first material composition or one or more first precursors of the first material composition. A melting point of the first material composition can be greater than or equal to a first temperature. The method can further comprise heating the initial pellet at a second sintering temperature to form a sintered structure. The sintered structure can comprise a plurality of grains formed by the first material composition. The method can also comprise coating a surface of the sintered structure with a second material composition or one or more second precursors of the second material composition. The second material composition can be different from the first material composition. A melting point of the second material composition can be less than the first temperature. The method can also comprise subjecting the coated sintered structure to a high-temperature heating pulse so as to convert the coated sintered structure into a solid-state ion-conducting structure. The high-temperature heating pulse can comprise exposure to a first sintering temperature of at least 600 K for a duration less than or equal to 60 seconds. Within the solid-state ion-conducting structure, the second material composition can wet boundaries of the plurality of grains and/or fill voids between adjacent grains. Each of the first and second material compositions can have an ionic conductivity greater than or equal to approximately 1×10−4 S/cm.
Any of the various innovations of this disclosure can be used in combination or separately. This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. The foregoing and other objects, features, and advantages of the disclosed technology will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.
Embodiments will hereinafter be described with reference to the accompanying drawings, which have not necessarily been drawn to scale. Where applicable, some elements may be simplified or otherwise not illustrated in order to assist in the illustration and description of underlying features. Throughout the figures, like reference numerals denote like elements.
For purposes of this description, certain aspects, advantages, and novel features of the embodiments of this disclosure are described herein. The disclosed methods and systems should not be construed as being limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed embodiments, alone and in various combinations and sub-combinations with one another. The methods and systems are not limited to any specific aspect or feature or combination thereof, nor do the disclosed embodiments require that any one or more specific advantages be present, or problems be solved. The technologies from any embodiment or example can be combined with the technologies described in any one or more of the other embodiments or examples. In view of the many possible embodiments to which the principles of the disclosed technology may be applied, it should be recognized that the illustrated embodiments are exemplary only and should not be taken as limiting the scope of the disclosed technology.
Although the operations of some of the disclosed methods are described in a particular, sequential order for convenient presentation, it should be understood that this manner of description encompasses rearrangement, unless a particular ordering is required by specific language set forth below. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed methods can be used in conjunction with other methods. Additionally, the description sometimes uses terms like “provide” or “achieve” to describe the disclosed methods. These terms are high-level abstractions of the actual operations that are performed. The actual operations that correspond to these terms may vary depending on the particular implementation and are readily discernible by one skilled in the art.
The disclosure of numerical ranges should be understood as referring to each discrete point within the range, inclusive of endpoints, unless otherwise noted. Unless otherwise indicated, all numbers expressing quantities of components, molecular weights, percentages, temperatures, times, and so forth, as used in the specification or claims are to be understood as being modified by the term “about.” Accordingly, unless otherwise implicitly or explicitly indicated, or unless the context is properly understood by a person skilled in the art to have a more definitive construction, the numerical parameters set forth are approximations that may depend on the desired properties sought and/or limits of detection under standard test conditions/methods, as known to those skilled in the art. When directly and explicitly distinguishing embodiments from discussed prior art, the embodiment numbers are not approximates unless the word “about” is recited. Whenever “substantially,” “approximately,” “about,” or similar language is explicitly used in combination with a specific value, variations up to and including 10% of that value are intended, unless explicitly stated otherwise.
Directions and other relative references may be used to facilitate discussion of the drawings and principles herein but are not intended to be limiting. For example, certain terms may be used such as “inner,” “outer,” “upper,” “lower,” “top,” “bottom,” “interior,” “exterior,” “left,” right,” “front,” “back,” “rear,” and the like. Such terms are used, where applicable, to provide some clarity of description when dealing with relative relationships, particularly with respect to the illustrated embodiments. Such terms are not, however, intended to imply absolute relationships, positions, and/or orientations. For example, with respect to an object, an “upper” part can become a “lower” part simply by turning the object over. Nevertheless, it is still the same part, and the object remains the same.
As used herein, “comprising” means “including,” and the singular forms “a” or “an” or “the” include plural references unless the context clearly dictates otherwise. The term “or” refers to a single element of stated alternative elements or a combination of two or more elements unless the context clearly indicates otherwise.
Although there are alternatives for various components, parameters, operating conditions, etc. set forth herein, that does not mean that those alternatives are necessarily equivalent and/or perform equally well. Nor does it mean that the alternatives are listed in a preferred order, unless stated otherwise. Unless stated otherwise, any of the groups defined below can be substituted or unsubstituted.
Unless explained otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one skilled in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure, suitable methods and materials are described below. The materials, methods, and examples are illustrative only and not intended to be limiting. Features of the presently disclosed subject matter will be apparent from the following detailed description and the appended claims.
The following is provided to facilitate the description of various aspects of the disclosed subject matter and to guide those skilled in the art in the practice of the disclosed subject matter.
High-temperature Heating Pulse: Application of a sintering temperature for a time period having a duration less than or equal to about 60 seconds. In some embodiments, the duration of the time period of heating pulse application is less than 30 seconds, for example, less than or equal to 20 seconds. For example, in some embodiments, the duration of the heating pulse can be in a range of about 10 seconds to about 20 seconds, inclusive. In some embodiments, the heating pulse may involve heating to the sintering temperature at a ramp rate of at least 103 K/s (e.g., about 105 K/s) prior to the sintering time period, and/or cooling from the sintering temperature at a ramp rate of at least 103 K/s (e.g., about 105 K/s).
Sintering temperature: A peak or maximum temperature at a surface of one or more heating elements when energized (e.g., by application of a current pulse) and/or at a surface of a material being heated. In some embodiments, the sintering temperature is at least about 600 K, for example, at least 1000 K. In some embodiments, the sintering temperature is at least 1200 K, for example, in a range of about 1500 K to about 3000 K, inclusive. In some embodiments, the sintering temperature is a maximum temperature experienced by a volatile sintering aid or filler, but which is otherwise insufficient to cause sintering of a base material or matrix (e.g., a temperature in a range of 600-1000 K, inclusive), for example, when the sintering aid or filler is melted for incorporation into a previously-sintered structure formed by the matrix. In some embodiments, a temperature at a material being sintered (e.g., precursors on a substrate) can match or substantially match (e.g., within 10%) the temperature of the heating element.
Grain: In a crystalline solid, a region of multiple particles having an uninterrupted crystal structure. The interface between two grains in the crystalline solid forms a grain boundary.
Grain size: A cross-sectional dimension (e.g., diameter) of crystals within a crystalline solid (e.g., a sintered ceramic material, such as an ionic conductor). In some embodiments, an identified grain size represents an average size for all grains (e.g., an average of the maximum cross-sectional dimensions). In some embodiments, the grain size can be measured according to one or more known standards, such as, but not limited to, ASTM E112-13, entitled “Standard Test Methods for Determining Average Grain Size” and published Nov. 17, 2021, and ISO 643:2019, entitled “Steels—Micrographic Determination of the Apparent Grain Size” and published March 2020, all of which are incorporated by reference herein.
NASICON: Sodium-based super ionic conductors, for example, having a chemical formula of Na1+xZr2SixP3-xO12, where 0<x<3. In some embodiments, Zr, Si, and/or Na in the chemical formula can be replaced by an isovalent element, such as V. Sb, or Ta.
LISICON: Lithium-based super ionic conductor, for example, having a chemical formula of Li2+2xZn1-xGeO4.
Relative Density: The ratio of the measured density of a sintered structure to the theoretical maximum density of the primary material (e.g., first material composition) of the sintered structure.
Grain Boundary Wetting: The coating of grain boundaries of a first material composition in a sintered structure by a second material composition different from the first material composition. In some embodiments, the second material composition has a melting temperature less than that of the first material composition, and/or the second material composition has an electronic conductivity less than that of the first material composition.
Disclosed herein are composite solid-state structures formed by sintering and incorporating fillers (also referred to herein as sintering aids) therein, which composite structures would otherwise be unattainable by conventional sintering techniques due to volatility of the fillers. In embodiments, the fillers can be incorporated using a high-temperature heating pulse (e.g., ≤60 s in duration), enabled at least in part by fast temperature ramping and/or cooling rates (e.g., ≥103 K/s). Due to the short duration of applied heating (e.g., seconds as opposed to the several hours required by conventional sintering), fillers will not decompose or severely volatilize, and a dense composite structure can be obtained. Accordingly, the candidate space of available fillers for incorporation can be expanded, and an appropriate filler can be selected to enhance performance of the composition structure for a particular application.
In some embodiments, the composite solid-state structure can be formed as an ion conductor, for example, to conduct metal ions (e.g., alkali metal ions, such as lithium (Li) ions, sodium (Na) ions, potassium (K) ions, etc., and/or alkaline earth metal ions, such as magnesium (Mg)) or anions (e.g., oxygen (O) ions). Referring to
The first material composition can have a melting temperature and/or a sintering temperature greater than the melting temperature of the second material composition. For example, the first material composition can have a melting temperature and/or sintering temperature greater than 1200 K, while the second material composition can have a melting temperature less than 1200 K (e.g., a melting point in a range of 500-1100 K). Thus, when the first material composition is subjected to a temperature to effect sintering thereof, the second material composition would be susceptible to loss via melting, decomposition, and/or sublimination. However, such loss can be avoided, or at least reduced, by employing the high-temperature heating pulse techniques disclosed herein.
After sintering, the microstructure of the ion-conducting structure 100 can exhibit a plurality of grains 102 formed by the first material composition, with the second material composition 104 wetting the grains 102 and/or filling voids (e.g., pinholes, gaps, or any other interstices) between adjacent grains 102. In some embodiments, the grains 102 of the first material composition can have a size less than or equal to 10 μm, for example, in a range of 1-5 μm, and/or the voids can have a size that is sub-micron (e.g., <1 μm). By filling at least some of the voids between adjacent grains 102, the second material composition 104 can allow the structure 100 to achieve a higher relative density than otherwise possible without the filler, for example, greater than 93% (e.g., ˜95% relative density). Alternatively or additionally, in some embodiments, by filling at least some of the voids between adjacent grains 102, the second material composition 104 can allow the structure 100 to exhibit improved mechanical properties (e.g., a mechanical strength ≥10 MPa).
In some embodiments, for example, when the ion-conducting structure is used as a solid-state electrolyte (SSE) for a battery, the first and second material compositions can be selected such that the resulting ion-conducting structure 100 has a high ionic conductivity (e.g., ≥˜1×10−3 S/cm) and a low electronic conductivity (e.g., ≤1×10−8 S/cm, such as ˜2×10−9 S/cm). For example, the first material composition and/or the second material composition can have an ionic conductivity of at least 1×10−4 S/cm. Alternatively or additionally, the first material composition and/or the second material composition can have an electronic conductivity of 1×10−8 S/cm or less. In some embodiments, the second material composition can have an electronic conductivity that is less than that of the first material composition, for example, at least one order of magnitude less than that of the first material composition. For example, in some embodiments, the second material composition has an electronic conductivity no greater than 1×10−10 S/cm (e.g., less than or equal to 10−11 S/cm, such as 10−12 S/cm), and the first material composition has an electronic conductivity no greater than 1×10−8 S/cm (e.g., ≤10−9).
In some embodiments, the first material composition, the second material composition, or both can include the element corresponding to the desired ion to be conducted, among other constituent elements. For example, when the ion-conducting structure is used as an SSE for an Li ion battery, the first material composition and/or the second material composition can comprise Li. In some embodiments, the first material composition can satisfy a chemical formula of LiALaBM′CM″DZrEOF, LiALaBM′CM″DTaEOF, or LiALaBM′CM″DNbEOF, where 4<A<8.5, 1.5<B<4, 0≤C≤2, 0≤D≤2, 0≤E<2, and 10<F<13, M′ is a first one selected from Al, Mo, W, Nb, Sb, Ca, Ba, Sr, Ce, Hf, Rb, or Ta, and M″ is a second one selected from Al, Mo, W, Nb, Sb, Ca, Ba, Sr, Ce, Hf, Rb, or Ta. Alternatively, is some embodiments, the first material composition can satisfy a chemical formula of LiALaBZrCAlDM′″EOF, where 5<A<7.7, 2<B<4, 0<C≤2.5, 0≤D<2, 0≤E<2, and 10<F<13, and M′″ is Nb, Ta, V, W, Mo, or Sb. For example, the SSE formed by sintering of the first material composition can be selected from the group consisting of perovskite-type Li3xLa2/3−xTiO3, NASICON-type Li1.3Al0.3Ti1.7(PO4)3, NASICON-type Li1+xAlxGe2−x(PO4)3, garnet-type Li7La3Zr2O12 (LLZO), garnet-type Li7La3Zr1.4Ta0.6O12 (LLTZO), LISICON-type Li14Zn(GeO4)4, thio-LISICON-type Li4−xGe1−xPxS4, argyrodite-type Li6PS5Cl, and anti-perovskite-type Li3OCl. The properties of such exemplary SSE materials are provided below in Table 2.
In some embodiments, the second material composition can be a composition that lacks any oxygen and has an electronic conductivity no greater than 10−12 S/cm. Alternatively or additionally, in some embodiments, the second material composition can be a composition that lacks any oxygen and has an electronic conductivity no greater than 10−10 S/cm. For example, the second material composition can be selected from the group consisting of LiCl, LiBr, LiI, LiF, Li3N, LiBH4, and LiBF4. Alternatively, in some embodiments, the second material composition can be a composition that includes oxygen. For example, the second material composition can be Li3BO3 or Li3PO4. The properties of such exemplary filler materials are provided below in Table 1.
Although Tables 1 and 2 and the description above has mentioned specific material compositions, embodiments of the disclosed subject matter are not limited thereto. Rather, other material compositions are also possible according to one or more contemplated embodiments, for example, to accommodate different ions for conduction, to provide different performance metrics (e.g., higher ionic conductivity and/or lower electronic conductivity), to provide different fabrication limits (e.g., different melting points and/or sintering temperatures), to provide different mechanical properties (e.g., mechanical strength), or for any other reason.
As mentioned above, in some embodiments, the ion-conducting structure 100 of
Through the anode 112 and cathode 114, the battery 110 may be coupled via an appropriate electrical circuit to node 116, which may be an electrical load for use of charge stored by the battery or a power source for recharging the battery. In some embodiments, the battery 110 can be a Li ion battery. For example, anode 112 can be formed of solid Li metal. The use of the second material composition to fill voids between grains in the ion-conducting structure 100 can result in a dense microstructure that, together with the high ionic conductivity and low electronic conductivity of the second material composition, improves electrochemical performance of the battery and/or prevents (or at least reduces) Li dendrite penetration through the SSE. For example, battery 110 can exhibit a critical current density (CCD) of at least 2 mA/cm2, an areal specific resistance (ASR) less than or equal to 50 Ω·cm2 (e.g., ˜35 Ω·cm2), and/or an electrochemical stability window of at least 4 V.
<10−10
Referring to
The method 220 can proceed to process block 230, where the composite pellet is subjected to one or more high-temperature heating pulses so as to covert the mixture into a solid-state ion conductor. In some embodiments, the heating pulse includes a peak temperature greater than a sintering temperature of the first material composition for a duration less than or equal to 60 seconds, after which the heating can be removed and the pellet allowed to cool to ambient temperature, for example, as shown in
In some embodiments, the pulse of high temperature can be achieved by moving the pellet through a spatially-restricted heating zone (e.g., where duration of the heating is determined by the size of the heating zone and speed of the pellet through the heating zone). Alternatively or additionally, in some embodiments, the pulse of high temperature can be achieved via pulsed operation of a heating element. In some embodiments, the high-temperature heating of process block 230 can be performed in a batch manner, for example, where the composite pellets are conveyed to a heating zone, maintained substantially stationary during exposure to the sintering temperature, and then conveyed out of the heating zone during or after cooling. Alternatively, in some embodiments, the high-temperature heating of process block 230 can be performed in a continuous manner, for example, where the composite pellets are conveyed into and through the heating zone at the same time a heating element provides the peak temperature. In such embodiments, the transit time through the heating zone and operation of the heating element can be coordinated to ensure that each composite pellet passing through the heating zone is exposed to the peak temperature for a cumulative amount of time substantially equivalent to a desired sintering duration (e.g., less than a predetermined maximum time).
The method 220 can proceed to process block 232, where the solid-state ion conductor can be adapted for use in a particular application. For example, in some embodiments, the solid-state ion conductor can be used as an SSE in a solid-state battery. In such applications, process block 232 can include assembling the SSE together with an anode and a cathode to form a battery. In some embodiments, the anode and/or the cathode can be coupled to opposite sides of the SSE. Alternatively or additionally, in some embodiments, the anode and/or the cathode can be integrally formed on a respective surface of the SSE, for example, by sintering a layer directly on the SSE (e.g., as described in International Publication No. WO 2020/236767, published Nov. 26, 2020 and entitled “High temperature sintering systems and methods,” which is incorporated herein by reference).
Although illustrated separately, it is contemplated that various process blocks may occur simultaneously or iteratively. Furthermore, certain process blocks illustrated as occurring after others may indeed occur before. Although some of blocks 224-232 of method 220 have been described as being performed once, in some embodiments, multiple repetitions of a particular process block may be employed before proceeding to the next decision block or process block. In addition, although blocks 224-232 of method 220 have been separately illustrated and described, in some embodiments, process blocks may be combined and performed together (simultaneously or sequentially). Moreover, although
As with the single-stage sintering process, the second material composition can be retained in the final structure because of the short exposure to high temperature. In addition, because the infiltration of the second material composition is decoupled from the sintering of the first material composition, the temperature of the heating pulse 314 for the second material composition can be less than the temperature of the sintering 302 for the first material composition, which temperature decoupling may help to further preserve the second material composition in the final structure. For example, the temperature of the heating pulse 314 can be less than the sintering temperature of the first material composition (e.g., <1100 K), and the temperature of the sintering 302 can be greater or equal to the sintering temperature of the first material composition (e.g., ≥1100 K).
Referring to
If sintering via high-temperature heating pulse is desired, the method 320 can proceed to process block 330, where the green pellet is subjected to one or more high-temperature heating pulses so as to convert the powder of first material composition into a sintered structure. In some embodiments, the heating pulse includes a peak temperature (e.g., second temperature) greater than a sintering temperature of the first material composition for a duration less than or equal to 60 seconds (e.g., 10-20 seconds), after which the heating can be removed and the pellet allowed to cool to ambient temperature, for example, as shown in
Alternatively, if sintering via high-temperature heating pulse is not desired, the method 320 can proceed to process block 332, where the green pellet is heated in a furnace so as to convert the powder of first material composition into the sintered structure. In some embodiments, the furnace heating is at a substantially constant temperature (e.g., second temperature) greater than a sintering temperature of the first material composition for a duration of at least 1 hour (e.g., ˜6 hours). In some embodiments, the furnace temperature can be greater than or equal to 1000 K (e.g., ˜1400 K).
From either process block 330 or process block 332, the method 320 can proceed to process block 334, where the sintered structure can be coated with one or more second material compositions. In some embodiments, the coating can be provided on a top surface of the sintered structure. Alternatively or additionally, the coating can be provided on multiple surfaces of the sintered structure, for example, as a conformal coating over some or all exposed surfaces of the sintered structure.
The method 320 can proceed to process block 336, where the sintered structure with coating can be subjected to one or more high-temperature heating pulses so as to convert the structure into a solid-state ion conductor. In some embodiments, the heating pulse includes a peak temperature greater than a melting temperature of the second material composition for a duration less than or equal to 60 seconds, after which the heating can be removed and the pellet allowed to cool to ambient temperature, for example, as shown in
In some embodiments, the pulse of high temperature (e.g., process block 330 and/or 336) can be achieved by moving the initial structure through a spatially-restricted heating zone (e.g., where duration of the heating is determined by the size of the heating zone and speed of the structure through the heating zone). Alternatively or additionally, in some embodiments, the pulse of high temperature can be achieved via pulsed operation of a heating element. In some embodiments, the high-temperature heating (e.g., process block 330 and/or 336) can be performed in a batch manner, for example, where the initial structure is conveyed to a heating zone, maintained substantially stationary during exposure to the sintering or peak temperature, and then conveyed out of the heating zone during or after cooling. Alternatively, in some embodiments, the high-temperature heating (e.g., process block 330 and/or 336) can be performed in a continuous manner, for example, where the initial structure is conveyed into and through the heating zone at the same time a heating element provides the corresponding sintering or peak temperature. In such embodiments, the transit time through the heating zone and operation of the heating element can be coordinated to ensure that each structure passing through the heating zone is exposed to the corresponding sintering or peak temperature for a cumulative amount of time substantially equivalent to a desired duration (e.g., less than a predetermined maximum time).
Although illustrated separately, it is contemplated that various process blocks may occur simultaneously or iteratively. Furthermore, certain process blocks illustrated as occurring after others may indeed occur before. Although some of blocks 232, 324-336 of method 320 have been described as being performed once, in some embodiments, multiple repetitions of a particular process block may be employed before proceeding to the next decision block or process block. In addition, although blocks 232, 324-336 of method 320 have been separately illustrated and described, in some embodiments, process blocks may be combined and performed together (simultaneously or sequentially). Moreover, although
In any of the disclosed examples, the heating source (e.g., one or more Joule heating elements) can subject the first material composition (e.g., the base or matrix material of the ion-conducting structure) and/or the second material composition (e.g., the sintering aid and/or filler) to one or more high-temperature heating pulses to effective formation of a sintered, composite ion-conducting structure. For example, a controller can control an electrical power source to apply a short-duration current pulse to the Joule heating element that causes the heating element to rapidly increase to the sintering temperature, dwell at the sintering temperature for a predetermined time period, and then rapidly cool from the sintering temperature.
For example,
In some embodiment, the high-temperature heating pulse can be provided by Joule heating, microwave heating, laser heating, electron beam heating, spark discharge heating, or any other heating mechanism capable of providing the sintering temperature, heating rate, and/or cooling rate. For example, the systems and methods for providing the high-temperature heating pulse can be similar to those disclosed in International Publication No. WO 2020/236767, published Nov. 26, 2020 and entitled “High temperature sintering systems and methods,” and International Publication No. WO 2022/204494, published Sep. 29, 2022, published Sep. 29, 2022 and entitled “High temperature sintering furnace systems and methods,” both of which are incorporated herein by reference.
In some embodiments, the high-temperature heating pulse can be terminated by conveying the sintered structures out of a heating zone and/or by de-activating, de-energizing, or otherwise terminating operation of the heating elements. Alternatively or additionally, in some embodiments, cooling at the end of a heating pulse can be achieved using one or more passive cooling features (e.g., heat sinks thermally coupled to the heating element and/or sintered structures, etc.), one or more active cooling features (e.g., fluid flow directed at the sintered structures and/or the heater, fluid flow through a heat sink thermally coupled thereto, etc.), or any combination thereof.
With reference to
A computing system may have additional features. For example, the computing environment 431 includes storage 461, one or more input devices 471, one or more output devices 481, and one or more communication connections 491. An interconnection mechanism (not shown) such as a bus, controller, or network interconnects the components of the computing environment 431. Typically, operating system software (not shown) provides an operating environment for other software executing in the computing environment 431, and coordinates activities of the components of the computing environment 431.
The tangible storage 461 may be removable or non-removable, and includes magnetic disks, magnetic tapes or cassettes, CD-ROMs, DVDs, or any other medium which can be used to store information in a non-transitory way, and which can be accessed within the computing environment 431. The storage 461 can store instructions for the software 433 implementing one or more innovations described herein.
The input device(s) 471 may be a touch input device such as a keyboard, mouse, pen, or trackball, a voice input device, a scanning device, or another device that provides input to the computing environment 431. The output device(s) 471 may be a display, printer, speaker, CD-writer, or another device that provides output from computing environment 431.
The communication connection(s) 491 enable communication over a communication medium to another computing entity. The communication medium conveys information such as computer-executable instructions, audio or video input or output, or other data in a modulated data signal. A modulated data signal is a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media can use an electrical, optical, radio-frequency (RF), or another carrier.
Any of the disclosed methods can be implemented as computer-executable instructions stored on one or more computer-readable storage media (e.g., one or more optical media discs, volatile memory components (such as DRAM or SRAM), or non-volatile memory components (such as flash memory or hard drives)) and executed on a computer (e.g., any commercially available computer, including smart phones or other mobile devices that include computing hardware). The term computer-readable storage media does not include communication connections, such as signals and carrier waves. Any of the computer-executable instructions for implementing the disclosed techniques as well as any data created and used during implementation of the disclosed embodiments can be stored on one or more computer-readable storage media. The computer-executable instructions can be part of, for example, a dedicated software application or a software application that is accessed or downloaded via a web browser or other software application (such as a remote computing application). Such software can be executed, for example, on a single local computer (e.g., any suitable commercially available computer) or in a network environment (e.g., via the Internet, a wide-area network, a local-area network, a client-server network (such as a cloud computing network), or any other such network) using one or more network computers.
For clarity, only certain selected aspects of the software-based implementations are described. Other details that are well known in the art are omitted. For example, it should be understood that the disclosed technology is not limited to any specific computer language or program. For instance, aspects of the disclosed technology can be implemented by software written in C++, Java™, Python®, and/or any other suitable computer language. Likewise, the disclosed technology is not limited to any particular computer or type of hardware. Certain details of suitable computers and hardware are well known and need not be set forth in detail in this disclosure.
It should also be well understood that any functionality described herein can be performed, at least in part, by one or more hardware logic components, instead of software. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), Program-specific Integrated Circuits (ASICs), Program-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc.
Furthermore, any of the software-based embodiments (comprising, for example, computer-executable instructions for causing a computer to perform any of the disclosed methods) can be uploaded, downloaded, or remotely accessed through a suitable communication means. Such suitable communication means include, for example, the Internet, the World Wide Web, an intranet, software applications, cable (including fiber optic cable), magnetic communications, electromagnetic communications (including RF, microwave, and infrared communications), electronic communications, or other such communication means. In any of the above-described examples and embodiments, provision of a request (e.g., data request), indication (e.g., data signal), instruction (e.g., control signal), or any other communication between systems, components, devices, etc. can be by generation and transmission of an appropriate electrical signal by wired or wireless connections.
Tantalum-doped lithium lanthanum zirconium oxide (LLZTO) was used as a matrix for a solid-state electrolyte (SSE). Lithium nitride (Li3N), which is highly Li+-conductive but also highly volatile, was used as a filler in the composite SSE. While Li3N has been used as a solid electrolyte interface (SEI) component or an artificial SEI layer, it has not previously been used as a filler or sintering aid, as it can otherwise be decomposed and evaporated from extended sintering times. To fabricate the composite SSE, a mixture of LLZTO and Li3N powders were milled together in controlled weight ratios (e.g., 1 wt %). The resulting mixture were then uniaxially pressed into green pellets for subsequent sintering using the above-described pulsed heating approach. The preparation of the composite pellets and subsequent sintering were conducted in an argon-filled glovebox.
Two pieces of carbon felt (e.g., 8×1.5 cm) were fixed on a graphite holder to act as Joule heating elements, and the green composite pellet was disposed between and in contact with the Joule heating elements. The sintering was implemented using an energy input from a DC power supply through the graphite holder to each carbon felt. Each Joule heating element can be quickly ramped (e.g., on the order of seconds or less, for example, within ˜3 seconds) to the sintering temperature via application of an appropriate current waveform from the DC power supply. During the sintering process, the temperature (e.g., ˜1600 K) was maintained for less than a minute (e.g., on the order of tens of seconds, for example, ˜20 seconds) until the pressed composite green pellets on the heating elements became dense. Temperature of the heating elements was determined using optical means (e.g., a visible-near-infrared spectrometer). Power was then removed from the heating elements, thereby allowing the sintered structures (e.g., Li3N/LLZTO SSE membranes) to quickly cool to room temperature (e.g., on the order of seconds or less, for example, within ˜3 seconds).
The Li3N/LLZTO SSE membranes were investigated by scanning electron microscopy (SEM) imaging. As shown in
To visualize the locations of Li3N filler within the sintered structure, energy dispersive spectroscopy (EDS) was used to map the elemental distribution of nitrogen (N), oxygen (O), tantalum (Ta), zirconium (Zr), and lanthanum (La) on a selected spot of the fractured Li3N/LLZTO SSE membrane, the results of which are shown in
As previously noted, the incorporation of the highly-volatile Li3N filler was unattainable using conventional furnace sintering. To illustrate this, a composite green pellet (made by the same process described above) was sintered using a furnace at 1150° C. (1423 K) for 6 hours. While the microstructure of the resulting sintered pellet was found to be comparably dense (˜93% relative density), the elemental mapping results showed almost no N signal, indicating substantial loss of Li3N during the prolonged exposure to high temperature required by the conventional sintering process.
Sintered pellets containing different loading of Li3N filler was performed, in particular, for filler loading ranging from 2-5 wt %. As shown in the SEM images of
The physiochemical properties of the Li3N/LLZTO SSE membranes synthesized via the disclosed high-temperature pulsed heating techniques were examined. In particular, X-ray diffraction (XRD) was carried out for LLZTO membranes with and without the Li3N filler. As shown in
X-ray photoelectron spectroscopy (XPS) was also conducted for the Li3N/LLZTO composite SSE membrane with respect to various elements. As shown in
As discussed above, the Li3N fills the voids, gaps and pinholes, as well as coats the grains of LLZTO, which can improve the electrochemical properties of the SSE membrane. To characterize the performance of the Li3N/LLZTO composite structure as a solid-state electrolyte, as compared to the filler-less LLZTO structure, a symmetric cell configuration was used. In particular, a Li|Li3N/LLZTO|Li symmetric cell was assembled by coating Li metal on opposite sides of a Li3N/LLZTO composite electrolyte. Electrochemical impedance spectroscopy (EIS) was measured at a frequency range from 100 mHz to 1 MHz with an amplitude of 10 mV. Li+ conductivity of the composite SSE was calculated according to the equation σ=D/(A×R), where D is the thickness, A is the area, and R is the resistance of the SSE. Galvanostatic charging/discharging of the Li|Li3N/LLZTO|Li symmetric cell was performed at different current densities with a step size of 30 mins. The measurements were performed in an argon-filled glovebox at room temperature. As illustrated in
In addition to the ionic conductivity, another key factor for the overall performance of a SSE membrane is the electronic conductivity, which was found to have an impact on the Li dendritic growth and penetration.
The critical current density (CCD) using a rate increment of 0.1 mA/cm2 and a duration of 10 minutes was measured. As shown in
The Li|LLZTO|Li and Li|Li3N/LLZTO|Li cells were further tested under galvanostatic conditions to compare their longtime cycling stability. Using a current density of 0.2 mA/cm2 with an areal capacity of 0.1 mAh/cm2, the Li|Li3N/LLZTO|Li cell demonstrated stable operation for 500 hours, as shown in
In view of the above-described implementations of the disclosed subject matter, this application discloses the additional examples in the clauses enumerated below. It should be noted that one feature of a clause in isolation, or more than one feature of the clause taken in combination, and, optionally, in combination with one or more features of one or more further clauses are further examples also falling within the disclosure of this application.
Clause 1. A solid-state ion-conducting structure comprising:
Clause 2. The solid-state ion-conducting structure of any clause or example herein, in particular, Clause 1, wherein the ionic conductivity of the second material composition is greater than or equal to 1×10−3 S/cm.
Clause 3. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-2, wherein the second material composition is less than or equal to 5 wt % of the solid-state ion-conducting structure.
Clause 4. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-3, wherein the second material composition is less than or equal to 2 wt % of the solid-state ion-conducting structure.
Clause 5. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-4, wherein the second material composition is less than or equal to 1 wt % of the solid-state ion-conducting structure.
Clause 6. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-5, wherein:
Clause 7. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-6, wherein:
Clause 8. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-7, wherein the first temperature is approximately 1200 K. Clause 9. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-8, wherein a mean grain size of the plurality of grains is approximately 10 μm or less.
Clause 10. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-9, wherein an areal specific resistance of the solid-state ion-conducting structure is less than or equal to 50 Ω·cm2.
Clause 11. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-10, wherein an areal specific resistance of the solid-state ion-conducting structure is approximately 35 Ω·cm2.
Clause 12. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-11, wherein an electrochemical stability window of the solid-state ion-conducting structure is at least 4 V.
Clause 13. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-12, wherein a mechanical strength of the solid-state ion-conducting structure is at least 10 MPa.
Clause 14. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-13, wherein the melting point of the second material composition is in a range of 500-1100 K, inclusive.
Clause 15. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-14, wherein:
Clause 16. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-15, wherein the second material composition is an inorganic metal salt or a non-oxide metal salt.
Clause 17. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-16, wherein the second material composition comprises LiCl, LiBr, LiI, LiF, Li3N, LiBH4, LiBF4, or any combination of the foregoing.
Clause 18. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-17, wherein:
Clause 19. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-17, wherein:
Clause 20. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-19, wherein the first material composition comprises perovskite-type Li3xLa2/3−xTiO3, NASICON-type Li1.3Al0.3Ti1.7(PO4)3, NASICON-type Li1+xAlxGe2−x(PO4)3, garnet-type Li7La3Zr2O12 (LLZO), garnet-type Li7La3Zr1.4Ta0.6O12 (LLTZO), LISICON-type Li14Zn(GeO4)4, thio-LISICON-type Li4−xGe1−xPxS4, argyrodite-type Li6PS5Cl, anti-perovskite-type Li3OCl, or any combination of the foregoing, wherein x represents a number.
Clause 21. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-20, wherein the first material composition is garnet-type Li7La3Zr1.4Ta0.6O12 (LLTZO) and the second material composition is Li3N.
Clause 22. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-21, wherein the solid-state ion-conducting structure is constructed as a solid-state electrolyte.
Clause 23. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-22, wherein the solid-state ion-conducting structure is constructed to conduct alkali metal ions, anions, or both.
Clause 24. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-23, wherein the solid-state ion-conducting structure is constructed to conduct lithium ions, sodium ions, potassium ions, oxygen ions, or any combination of the foregoing.
Clause 25. The solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-24, wherein a relative density of the solid-state ion-conducting structure is greater than 93%.
Clause 26. A battery comprising an anode, a cathode, and a solid-state electrolyte separating the anode from the cathode, the solid-state electrolyte comprising the solid-state ion-conducting structure of any clause or example herein, in particular, any one of Clauses 1-25.
Clause 27. The battery of any clause or example herein, in particular, Clause 26, wherein the anode is a lithium anode.
Clause 28. The battery of any clause or example herein, in particular, any one of Clauses 26-27, wherein the anode consists essentially of lithium.
Clause 29. The battery of any clause or example herein, in particular, any one of Clauses 26-28, wherein the battery exhibits a critical current density of at least 2 mA/cm2.
Clause 30. A method comprising:
Clause 31. A method comprising:
Clause 32. The method of any clause or example herein, in particular, Clause 31, wherein a thickness of the coating on the surface of the sintered structure is about 10% of a thickness of the sintered structure.
Clause 33. The method of any clause or example herein, in particular, any one of Clauses 31-32, wherein the heating the initial pellet at the second sintering temperature comprises subjecting the initial pellet to another high-temperature heating pulse so as to convert the initial pellet into a sintered structure, the another high-temperature heating pulse comprising exposure to the second sintering temperature for a duration of less than or equal to 60 seconds, the second sintering temperature being greater than the first sintering temperature.
Clause 34. The method of any clause or example herein, in particular, any one of Clauses 31-33, wherein the second sintering temperature is in a range of 1500-3000 K, inclusive.
Clause 35. The method of any clause or example herein, in particular, any one of Clauses 31-34, wherein the duration of the another high-temperature heating pulse is in a range of 10-20 seconds, inclusive.
Clause 36. The method of any clause or example herein, in particular, any one of Clauses 30-35, wherein a relative density of the solid-state ion-conducting structure is greater than 93%.
Clause 37. The method of any clause or example herein, in particular, any one of Clauses 30-36, wherein the duration of the high-temperature heating pulse is in a range of 10-20 seconds, inclusive.
Clause 38. The method of any clause or example herein, in particular, any one of Clauses 30-37, wherein the first sintering temperature is greater than or equal 1200 K.
Clause 39. The method of any clause or example herein, in particular, any one of Clauses 30-38, wherein the first sintering temperature is in a range of 1500-3000 K, inclusive.
Clause 40. The method of any clause or example herein, in particular, any one of Clauses 30-39, wherein the subjecting to the high-temperature heating pulse comprises heating to the first sintering temperature at a heating rate of at least 103 K/s.
Clause 41. The method of any clause or example herein, in particular, any one of Clauses 30-40, wherein the subjecting to the high-temperature heating pulse comprises heating to the first sintering temperature at a heating rate in a range of 103 to 105 K/s, inclusive.
Clause 42. The method of any clause or example herein, in particular, any one of Clauses 30-41, wherein the subjecting to the high-temperature heating pulse comprises cooling from the first sintering temperature at a cooling rate of at least 103 K/s.
Clause 43. The method of any clause or example herein, in particular, any one of Clauses 30-42, wherein the subjecting to the high-temperature heating pulse comprises cooling from the first sintering temperature at a cooling rate in a range of 103 to 105 K/s, inclusive.
Clause 44. The method of any clause or example herein, in particular, any one of Clauses 30-43, further comprising:
Clause 45. The method of any clause or example herein, in particular, Clause 44, wherein one of the electrodes comprises a lithium anode.
Clause 46. The method of any clause or example herein, in particular, any one of Clauses 30-45, wherein the ionic conductivity of the second material composition is greater than or equal to 1×10−3 S/cm.
Clause 47. The method of any clause or example herein, in particular, any one of Clauses 30-46, wherein the second material composition is less than or equal to 5 wt % of the solid-state ion-conducting structure.
Clause 48. The method of any clause or example herein, in particular, any one of Clauses 30-47, wherein the second material composition is less than or equal to 2 wt % of the solid-state ion-conducting structure.
Clause 49. The method of any clause or example herein, in particular, any one of Clauses 30-48, wherein the second material composition is less than or equal to 1 wt % of the solid-state ion-conducting structure.
Clause 50. The method of any clause or example herein, in particular, any one of Clauses 30-49, wherein:
Clause 51. The method of any clause or example herein, in particular, any one of Clauses 30-50, wherein:
Clause 52. The method of any clause or example herein, in particular, any one of Clauses 30-51, wherein the first temperature is approximately 1200 K.
Clause 53. The method of any clause or example herein, in particular, any one of Clauses 30-52, wherein a mean grain size of the plurality of grains is approximately 10 μm or less.
Clause 54. The method of any clause or example herein, in particular, any one of Clauses 30-53, wherein the melting point of the second material composition is in a range of 500-1100 K, inclusive.
Clause 55. The method of any clause or example herein, in particular, any one of Clauses 30-54, wherein:
Clause 56. The method of any clause or example herein, in particular, any one of Clauses 30-55, wherein the second material composition is an inorganic metal salt or a non-oxide metal salt.
Clause 57. The method of any clause or example herein, in particular, any one of Clauses 30-56, wherein the second material composition comprises LiCl, LiBr, LiI, LiF, Li3N, LiBH4, LiBF4, or any combination of the foregoing.
Clause 58. The method of any clause or example herein, in particular, any one of Clauses 30-57, wherein:
the first material composition comprises a compound having a formula of LiALaBM′CM″DZrEOF, LiALaBM′CM″DTaEOF, or LiALaBM′CM″DNbEOF;
Clause 59. The method of any clause or example herein, in particular, any one of Clauses 30-57, wherein:
Clause 60. The method of any clause or example herein, in particular, any one of Clauses 30-59, wherein the first material composition comprises perovskite-type Li3xLa2/3−xTiO3, NASICON-type Li1.3Al0.3Ti1.7(PO4)3, NASICON-type Li1+xAlxGe2−x(PO4)3, garnet-type Li7La3Zr2O12 (LLZO), garnet-type Li7La3Zr1.4Ta0.6O12 (LLTZO), LISICON-type Li14Zn(GeO4)4, thio-LISICON-type Li4−xGe1−xPxS4, argyrodite-type Li6PS5Cl, anti-perovskite-type Li3OCl, or any combination of the foregoing, wherein x represents a number.
Clause 61. The method of any clause or example herein, in particular, any one of Clauses 30-60, wherein the first material composition is garnet-type Li7La3Zr1.4Ta0.6O12 (LLTZO) and the second material composition is Li3N.
Clause 62. The method of any clause or example herein, in particular, any one of Clauses 30-61, wherein the solid-state ion-conducting structure conducts alkali metal ions, anions, or both.
Clause 63. The method of any clause or example herein, in particular, any one of Clauses 30-62, wherein the solid-state ion-conducting structure conducts lithium ions, sodium ions, potassium ions, oxygen ions, or any combination of the foregoing.
Any of the features illustrated or described herein, for example, with respect to
The present application claims the benefit of U.S. Provisional Application No. 63/261,947, filed Sep. 30, 2021, entitled “Solid-State Electrolyte Materials with Volatile Sintering Aids and Methods of Making and Using the Same,” which is incorporated by reference herein in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US22/45326 | 9/30/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63261947 | Sep 2021 | US |
