Sol-GEL produced solid electrolyte and electrode for a solid-state battery, and a method for producing the same

Abstract

The technology of the present disclosure generally relates to the field of power storage devices, and more specifically to a solid electrolyte, an electrode, electrode assemblies, solid electrolyte separators, a solid- state battery, and a process for producing the same. An aspect of the present disclosure relates to a process for producing a solid electrolyte, the process comprising the steps of: - providing a curable composition comprising • a polyether compound comprising at least one polyalkoxy silyl funconal group; • a cross-linker comprising at least two polyalkoxy silyl funconal groups and a metal ion (M+) chelang moiety; • a metal (M+) salt, preferably a lithium (Li+) salt; • clay mineral parcles; • oponally, an ionically conducve compound; and • a solvent comprising water, and preferably one or more alcohols; - curing the curable composion, thereby obtaining the solid electrolyte; and, - oponally, drying the solid electrolyte.

Description

[0001] SOL-GEL PRODUCED SOLID ELECTROLYTE AND ELECTRODE FOR A SOLID-STATE BATTERY, AND A

[0002] METHOD FOR PRODUCING THE SAME

[0003] FIELD OF THE INVENTION

[0004] The technology of the present disclosure generally relates to the field of power storage devices, and more specifically to a solid electrolyte, an electrode, electrode assemblies, solid electrolyte separators, a solid- state battery, and a process for producing the same.

[0005] BACKGROUND

[0006] Electrochemical power storage devices, such as batteries and supercapacitors, are integral to numerous modern technologies, including portable electronics, electric vehicles, and renewable energy storage systems. To meet current and future market demands, electrolyte design and composition are becoming increasingly important. For instance, traditional liquid electrolytes, while effective, pose significant safety risks due to leakage, flammability, and potential for short-circuiting. Solid electrolytes offer a promising alternative, providing improved safety, mechanical stability, and potentially higher energy densities.

[0007] The sol-gel process is a versatile and cost-effective method for preparing polymeric solid electrolytes. This method involves the transition of a system from a liquid 'sol' (a colloidal suspension of particles) into a solid 'gel' phase. The sol-gel process is advantageous in that it allows for precise control over the composition and microstructure of the resulting material, enabling the tailoring of electrolyte properties to meet specific requirements of electrochemical power storage devices.

[0008] Despite these advantages, challenges remain in optimizing the ionic conductivity, mechanical integrity, and compatibility of sol-gel derived solid electrolytes with electrode materials. To address these challenges composite materials have been used comprising inorganic parts (typically providing mechanical strength) and organic parts (typically providing flexibility and optimizing ion transport).

[0009] For example, SAIKIA DIGANTA et al., in "Development of a New Crosslinked Highly Conductive Hybrid Electrolyte based on Polyetherdiamine, Diphenylmethane Diisocyanate and Organosilanes for Efficient Lithium-Metal Battery," Batteries & Supercaps, vol. 5, no. 12, December 2022; describes the development of a crosslinked organic-inorganic hybrid polymer electrolyte based on polyetherdiamine, isocyanate, organosilanes, and LiCIO4, through plasticization.

[0010] SAIKIA DIGANTA et al., in "A highly conductive organic-inorganic hybrid electrolyte based on cocondensation of di-ureasil and ethylene glycol-containing alkoxysilane," Electrochimica Acta, vol. 54, no. 27, 30 November 2009, pp. 7156-7166; describes hybrid polymer electrolytes based on di-ureasil structures formed by reacting polyether diamines with isocyanate-functional silanes, followed by cocondensation with an ethylene glycol-containing alkoxysilane in the presence of LiCIO4.

[0011] DEKA JUTI RANI et al., in "Design, synthesis and characterization of polysiloxane and polyetherdiamine based comb-shaped hybrid solid polymer electrolytes for applications in electrochemical devices," Materials Research Bulletin, vol. 109, 1 January 2019, pp. 72-81; describes the development of combshaped hybrid solid polymer electrolytes prepared via hydrosilylation and sol-gel reactions involving polymethylhydrosiloxane and polyether diamines, followed by LiCIO4doping.

[0012] SAIKIA DIGANTA et al., in "Organic-inorganic hybrid polymer electrolytes based on polyether diamine, alkoxysilane, and trichlorotriazine: Synthesis, characterization, and electrochemical applications," Journal of Power Sources, vol. 269, 7 July 2014, pp. 651-660; describes hybrid polymer electrolytes prepared by reacting polyether diamines with 2,4,6-trichloro-l,3,5-triazine and an alkoxysilane precursor, followed by LiCIO4doping.

[0013] However, composite materials remain limited by their own drawbacks and challenges. In particular, uneven distribution of inorganic and organic parts across and around the solid electrolyte structure can lead to several disadvantages that may impact the performance, reliability, and longevity of the resulting power storage devices. For example, non-uniform composition can create regions with poor ionic conductivity, disrupting the continuous pathways necessary for efficient ion transport. Moreover, this may create the formation of thermal hotspots or mechanical stress concentrations, increasing safety hazards and making the material more susceptible to cracking or fracturing. Such non-uniformity issues are typically observed in polymer grafted silica (nano)particles disclosed in the art.

[0014] Hence, there remains a need to address the aforementioned limitations by providing a solid electrolyte that has improved mechanical properties without reducing, and advantageously even improving, the ionic conductance. This is necessary for the development of commercially relevant solid-state batteries. Furthermore, to improve the safety of electrochemical power storage devices, there is a need for solid- state electrolytes with reduced flammability, and when ignited, these solid electrolytes should advantageously have a fast self-extinguishing time.

[0015] SUMMARY OF THE INVENTION

[0016] The technology of the present disclosure generally relates to the field of power storage devices, and more specifically to a solid electrolyte comprising a cured polymer network, optionally including an ionically conductive compound. The curing or crosslinking is achieved herein using a polyether compound and a cross-linker comprising a specified amount of polyalkoxy silyl functional groups (i.e., a functional group having one or more alkoxy groups (-OR) attached to a silicon atom) in the presence of a solvent. In particular, the alkoxy groups of the silyl functional group can react with water, leading to the formation of silanols (Si-OH) and alcohols (ROH), which may form siloxane bonds (Si-O-Si) through subsequent condensation reactions.

[0017] While cross-linking is typically associated with a decreased ionic conductivity due to inherent restrictions in ion mobility, it has been found that the specific combination of polyether compound and cross-linker as defined herein provide a structurally stable polymer network with significantly improved ionic conductivity. Thus, an advantage of the present solid electrolyte is its improved mechanical stability and ionic conductivity properties.

[0018] Another advantage of the present solid electrolyte is that it may exhibit improved thermal stability. Specifically, embodiments of the present solid electrolyte result in reduced to significantly reduced flammability of the solid electrolyte film, and / or improved to significantly improved self-extinguishing capabilities of the solid electrolyte film.

[0019] An overview of various aspects of the technology of the present disclosure is given hereinbelow, after which specific embodiments will be described in more detail. This overview is meant to aid the reader in understanding the technological concepts more quickly, but it is not meant to identify the most important or essential features thereof, nor is it meant to limit the scope of the present disclosure, which is limited only by the claims.

[0020] An aspect of the present disclosure relates to a process for producing a solid electrolyte, the process comprising the steps of: providing a curable composition, the curable composition comprising

[0021] • a polyether compound comprising at least one polyalkoxy silyl functional group;

[0022] • a cross-linker comprising at least two polyalkoxy silyl functional groups;

[0023] • a metal (M+) salt, preferably a lithium (Li+) salt;

[0024] • optionally, an ionically conductive compound; and

[0025] • a solvent comprising water, and preferably one or more alcohols; curing the curable composition, thereby obtaining the solid electrolyte; preferably, drying the solid electrolyte.

[0026] In particular embodiments, the process comprises the steps of: providing a curable composition comprising

[0027] • a polyether compound comprising at least one polyalkoxy silyl functional group;

[0028] • a cross-linker comprising at least two polyalkoxy silyl functional groups and a metal ion (M+) chelating moiety;

[0029] • a metal (M+) salt, preferably a lithium (Li+) salt;

[0030] • clay mineral particles;

[0031] • optionally, an ionically conductive compound; and

[0032] • a solvent comprising water, and preferably one or more alcohols; curing the curable composition, thereby obtaining the solid electrolyte; and, optionally, drying the solid electrolyte.

[0033] In particular embodiments, the curable composition may further comprise clay mineral particles; preferably wherein the clay mineral particles are selected from the group consisting of palygorskite, attapulgite, kaolin, smectite, illite, chlorite, sepiolite, vermiculite, and mixtures thereof; more preferably palygorskite, kaolin and / or attapulgite; more preferably wherein the clay mineral particles comprise halloysite nanotubes (HNT) comprising aluminosilicate (AI2Si2O5(OH)4).

[0034] In particular embodiments, the polyalkoxy silyl functional group may be a hydrolysable group, and is preferably selected from the group consisting of trialkoxy silyl (-SifOR^fOR^fOR3)), dialkoxy alkyl silyl (- Si(OR4)(OR5)(R6)), monoalkoxy dialkyl silyl (-Si(OR7)(R8)(R9)), and combinations thereof.

[0035] In particular embodiments, the polyether compound may comprise repeating units of Formula (I) and / or Formula (II)

[0036] In particular embodiments, the curable composition may further comprise a compound selected from the group consisting of tetraalkoxy silane, trialkoxy alkyl silane, dialkoxy dialkyl silane, alkoxy trialkyl silane, and mixtures thereof. In particular embodiments, the cross-linker may comprise a metal ion (M+) chelating moiety, and preferably wherein the metal ion (M+) chelating moiety is a cyclic moiety or a macrocyclic moiety.

[0037] In particular embodiments, the curable composition comprises: at least 0.5 wt.% of the cross-linker; with wt.% relative to the total weight of the curable composition.

[0038] In particular embodiments, the cross-linker comprises at least three polyalkoxy silyl functional groups; and is preferably selected from the group consisting of l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine- 2,4,6(lh,3h,5h)-trione, tris(3-(trimethoxysilyl)propyl)amine, l,l,l,3-tris(3-(triethoxysilyl) propyl) urea, and mixtures thereof.

[0039] Another aspect of the present disclosure relates to a solid electrolyte, for an electrochemical energy storage device, comprising a cured polymer network; wherein the cured polymer network comprises polyether chains; metal ions (M+), preferably lithium ions (Li+); optionally, an ionically conductive compound; cross-links having at least two bridging moieties; wherein each bridging moiety is independently selected from the group consisting of Formula (III), Formula (IV), and Formula (V)

[0040] (HI), (IV), (V).

[0041] In particular embodiments, the solid electrolyte comprises: a polymeric matrix comprising polyether chains; metal ions (M+), preferably lithium ions (Li+); metal ion (M+) chelating moieties; clay mineral particles; optionally, an ionically conductive compound; and, cross-links containing siloxane (-Si-O-Si-) bonds.

[0042] It should be noted that (preferred) embodiments and associated advantages of the process for producing a solid electrolyte according to an aspect of the present disclosure are also (preferred) embodiments of the solid electrolyte according to an aspect of the present disclosure and vice versa.

[0043] In particular embodiments, the cured polymer network may comprise a metal ion chelating moiety, and preferably wherein the metal ion chelating moiety is a cyclic moiety or a macrocyclic moiety.

[0044] In particular embodiments, the polyether chains may be connected to one another by bridging moieties as defined herein.

[0045] In particular embodiments the water content in the solid electrolyte is at most 1500 ppm preferably after drying, preferably at most 1000 ppm, more preferably at most 500 ppm or less, for example 100 ppm or 50 ppm.

[0046] In particular embodiments, the solid electrolyte further comprises a porous substrate embedded within the cured polymer-silica network.

[0047] Another aspect of the present disclosure relates to an electrode comprising a solid electrolyte according to the present disclosure and / or obtained or obtainable according to a process for producing a solid electrolyte according to the present disclosure and an electrode active material, preferably wherein the solid electrolyte forms a covering and / or coating layer on the electrode active material.

[0048] It should be noted that (preferred) embodiments and associated advantages of the process for producing a solid electrolyte according to an aspect of the present disclosure and the solid electrolyte according to another aspect of the present disclosure are also (preferred) embodiments of the electrode according to an aspect of the present disclosure and vice versa.

[0049] Another aspect of the present disclosure relates to a solid electrolyte separator, for an electrochemical energy storage device, comprising a cured polymer network and a porous substrate embedded with the cured polymer network; wherein the cured polymer network comprises polyether chains; metal ions (M+), preferably lithium ions (Li+); optionally, an ionically conductive compound; cross-links having at least two bridging moieties; wherein each bridging moiety is independently selected from the group consisting of Formula (III), Formula (IV), and Formula (V)

[0050] In particular embodiments the water content in the solid electrolyte separator is at most 1500 ppm preferably after drying, preferably at most 1000 ppm, more preferably at most 500 ppm or less, for example 100 ppm or 50 ppm.

[0051] It should be noted that (preferred) embodiments and associated advantages of the process for producing a solid electrolyte according to an aspect of the present disclosure, the solid electrolyte according to another aspect of the present disclosure and the electrode according to another aspect of the present disclosure are also (preferred) embodiments of the solid electrolyte separator according to an aspect of the present disclosure and vice versa.

[0052] In particular embodiments, the solid electrolyte separator may further comprise a layer of the cured polymer network positioned on at least one side of the porous substrate, preferably at least two layers of the cured polymer network positioned on at least two opposite sides of the porous substrate, wherein the layer is configured for ionically connecting to an active electrode material.

[0053] Another aspect of the present disclosure relates to an electrode assembly comprising an electrode according to an aspect of the present disclosure, and preferably one or more separators, more preferably one or more solid electrolyte separators according to an aspect of the present disclosure.

[0054] In particular embodiments, the electrode assembly comprises an electrode according to an aspect of the present disclosure and one or more separators, preferably in the form of a solid electrolyte according to an aspect of the present disclosure. It should be noted that (preferred) embodiments and associated advantages of the process for producing a solid electrolyte according to an aspect of the present disclosure, the solid electrolyte according to another aspect of the present disclosure, the electrode according to another aspect of the present disclosure, and the solid electrolyte separator according to another aspect of the present disclosure are also (preferred) embodiments of the electrode assembly according to an aspect of the present disclosure and vice versa.

[0055] In particular embodiments the water content in the electrode assembly is at most 1500 ppm preferably after drying, preferably at most 1000 ppm, more preferably at most 500 ppm or less, for example 100 ppm or 50 ppm.

[0056] Another aspect of the present disclosure relates to an electrochemical energy storage device, comprising a positive electrode, a negative electrode, and a solid electrolyte according to an aspect of the present disclosure and / or obtained or obtainable according to a process for producing a solid electrolyte according to the present disclosure.

[0057] In particular embodiments, the electrochemical energy storage device comprises a positive electrode, a negative electrode, and a solid electrolyte according an aspect of the present disclosure; preferably further comprising one or more separators in the form of a solid electrolyte according to an aspect of the present disclosure.

[0058] It should be noted that (preferred) embodiments and associated advantages of the process for producing a solid electrolyte according to an aspect of the present disclosure, the solid electrolyte according to another aspect of the present disclosure, the electrode according to another aspect of the present disclosure, the solid electrolyte separator according to another aspect of the present disclosure, and the electrode assembly according to another aspect of the present disclosure are also (preferred) embodiments of the electrochemical energy storage device according to an aspect of the present disclosure and vice versa.

[0059] In particular embodiments the water content in the electrode and / or the separator is at most 1500 ppm preferably after drying, preferably at most 1000 ppm, more preferably at most 500 ppm or less, for example 100 ppm or 50 ppm.

[0060] In particular embodiments, the electrochemical energy storage device may further comprise one or more separators, preferably one or more solid electrolyte separators according to an aspect of the present disclosure. The above and other characteristics, features and advantages of the present disclosure will become apparent from the following detailed description, which illustrate, by way of example, the principles of the disclosure.

[0061] DESCRIPTION OF THE FIGURES

[0062] The following description of the figures relate to specific embodiments of the disclosure which are exemplary in nature and not intended to limit the teachings or applications of the present disclosure in any way.

[0063] FIG. 1 is a graph illustrating the ionic conductivity of solid electrolytes SE1-SE4 according to an embodiment of the present invention and comparative solid electrolyte CE1, as a function of the weight percentage of VPS cross-linker.

[0064] FIG. 2 is a graph illustrating the storage modulus (G') and loss modulus (G") as a function of frequency of solid electrolytes SE1-SE4 according to an embodiment of the present invention and comparative solid electrolyte CE1.

[0065] FIG. 3 is a graph illustrating the damping factor of solid electrolytes SE1-SE4 according to an embodiment of the present invention and comparative solid electrolyte CE1, as a function of the weight percentage of VPS cross-linker.

[0066] FIG 4. is a graph illustrating the current density as a function of potential (V vs. Li / Li+) of solid electrolyte SE4 of Example 1 according to an embodiment of the present invention and comparative solid electrolyte CE1.

[0067] FIG 5. is a graph illustrating the current density as a function of time of solid electrolyte SE4 of Example 1 according to an embodiment of the present invention and comparative solid electrolyte CE1.

[0068] FIG 6. is a thermogram illustrating the weight percentage of solid electrolyte as a function of temperature of solid electrolyte SE4 of Example 1 according to embodiments of the present invention and comparative solid electrolyte CE1.

[0069] FIG 7. is a graph illustrating the voltage profile of lithium cathode 1 of Example 4 comprising solid electrolyte SE4 of Example 1 according to embodiments of the present invention.

[0070] FIG 8. is a graph illustrating the voltage profile of comparative lithium cathode 1 of Example 4 comprising comparative solid electrolyte CE1 according to embodiments of the present invention. FIG 9. is a graph illustrating the discharge specific capacity and coulombic efficiency of lithium cathode 1 of Example 4 comprising solid electrolyte SE4 of Example 1 according to an embodiment of the present invention, as a function of the number of cycles.

[0071] FIG 10. is a graph illustrating the discharge specific capacity and coulombic efficiency of comparative lithium cathode 1 of Example 4 comprising comparative solid electrolyte CE1 according to an embodiment of the present invention, as a function of the number of cycles.

[0072] FIG 11. is a graph illustrating the discharge specific capacity and coulombic efficiency of electrochemical energy storage device cell 1 (Cell 1) of Example 5 according to an embodiment of the present invention, comprising a solid electrolyte separator and an overfill of around 35 pm thickness, at C / 3 discharge and as a function of the number of cycles.

[0073] FIG 12. is a graph illustrating the discharge specific capacity and coulombic efficiency of electrochemical energy storage device cell 1 (Cell 1) of Example 5 according to an embodiment of the present invention, comprising a solid electrolyte separator and an overfill of around 35 pm thickness, at variable C-discharge and as a function of the number of cycles.

[0074] FIG 13. is a graph illustrating the discharge specific capacity and coulombic efficiency of electrochemical energy storage device cell 2 (Cell 2) of Example 5 according to an embodiment of the present invention, comprising a solid electrolyte separator and an overfill of around 35 pm thickness, at C / 3 discharge and as a function of the number of cycles.

[0075] FIG 14. is a graph illustrating the discharge specific capacity and coulombic efficiency of electrochemical energy storage device cell 2 (Cell 2) of Example 5 according to an embodiment of the present invention, comprising a solid electrolyte separator and an overfill of around 35 pm thickness, at variable C-discharge and as a function of the number of cycles.

[0076] FIG. 15 is a graph illustrating the ionic conductivity of solid electrolytes SE6 of Example 6 according to an embodiment of the present invention and comparative solid electrolyte CE2, as a function of temperature. FIG 16. is a graph illustrating the thermal properties of solid electrolytes SE6 of Example 6 according to an embodiment of the present invention and comparative solid electrolyte CE2, as a function of temperature.

[0077] DETAILED DESCRIPTION

[0078] In the following detailed description, the technology underlying the present disclosure will be described by means of different aspects thereof. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure. When describing specific embodiments, reference is made to the accompanying drawings, which are provided solely to aid in the understanding of the described embodiment.

[0079] In the present description, technology is described by means of which a solid electrolyte can be produced that is suitable for the manufacturing of a (solid-state) battery. More specifically, a solid electrolyte is disclosed comprising a crosslinked or cured polymer network, preferably a porous cured polymer network, that may be doped with a metal salt and optionally an ionically conductive compound. The cured polymer network is preferably obtained by a sol-gel process, as further described herein below, by reacting a polyether compound and a cross-linker comprising a specified amount of polyalkoxy silyl functional groups in the presence of a solvent.

[0080] Accordingly, an aspect of the present disclosure relates to a process for producing a solid electrolyte, the process comprising the steps of: providing a curable composition, the curable composition comprising

[0081] • a polyether compound comprising at least one polyalkoxy silyl functional group;

[0082] • a cross-linker comprising at least two polyalkoxy silyl functional groups;

[0083] • a metal (M+) salt, preferably a lithium (Li+) salt;

[0084] • optionally, an ionically conductive compound; and

[0085] • a solvent comprising water, and preferably one or more alcohols; curing the curable composition, thereby obtaining the solid electrolyte; preferably, drying the solid electrolyte.

[0086] In particular embodiments, the process comprises the steps of: providing a curable composition comprising

[0087] • a polyether compound comprising at least one polyalkoxy silyl functional group;

[0088] • a cross-linker comprising at least two polyalkoxy silyl functional groups and a metal ion (M+) chelating moiety;

[0089] • a metal (M+) salt, preferably a lithium (Li+) salt;

[0090] • clay mineral particles;

[0091] • optionally, an ionically conductive compound; and

[0092] • a solvent comprising water, and preferably one or more alcohols; curing the curable composition, thereby obtaining the solid electrolyte; and, optionally, drying the solid electrolyte.

[0093] The process according to the present disclosure has the advantage that the curing of the curable composition may occur fast, so that shaping of the solid electrolyte may become easier and long gelation times may be avoided. In addition, the process is very flexible in reaction conditions.

[0094] Advantageously, the present process may avoid the need for an inert atmosphere or dry conditions.

[0095] Another advantage of the present process is that it provides a solid electrolyte having improved mechanical stability (i.e., low brittleness, high elasticity and / or high strength) and ionic conductivity properties, despite being characterized by a high cross-linking degree.

[0096] Another advantage of the present solid electrolyte is that it may exhibit improved thermal stability. Specifically, embodiments of the present solid electrolyte result in reduced to significantly reduced flammability of the solid electrolyte, and / or improved to significantly improved self-extinguishing capabilities of the solid electrolyte.

[0097] Moreover, without wishing to be bound by theory, it is considered that the present cross-linker allows to improve the mechanical stability, without reducing the ionic conductivity, of the resulting solid electrolyte. In particular, despite creating a more interconnected structure, the functionality of the cross-linker allows to interact with the dissolved metal salt in the network, allowing to enhance the ionic conductivity and overall performance of the electrolyte. In other words, the present cross-linker allows to provide pathways for ion transport, while maintaining structural integrity and mechanical properties of the solid electrolyte. The term "solid" as used herein refers to being in solid state as a whole system at room temperature. It should be noted that partial inclusion of a liquid is not excluded. Gels, for example, are considered "solid". Hence, the "solid electrolyte" as disclosed herein refers to an electrolyte being in solid state at room temperature so that it is suitable for producing of a solid-state battery. Alternatively or in combination, the electrolyte can be referred to as a "composite electrolyte" based on the combination of constituent materials comprising a combination of inorganic and organic components as defined herein.

[0098] The term "polyalkoxysilyl functional group" as used herein refers to an alkoxysilane group comprising one or more alkoxy groups (-OR), such as one alkoxy group, two alkoxy groups, or three alkoxy groups, attached to a silicon atom. Hence, the prefix "poly-" as used herein may refer to one or more.

[0099] It should be noted that whenever in the present disclosure the silicon atom is substituted with less than three alkoxy groups, one or more alkyl groups are attached to the silicon atom instead, provided that the silicon atom's normal valency is not exceeded, and that the substitution results in a chemically stable compound. In some embodiments, the polyalkoxysilyl functional group may comprise two alkoxy groups and one alkyl group attached to the silicon atom.

[0100] In some embodiments, the polyalkoxysilyl functional group may comprise three alkoxy groups attached to the silicon atom. This provides functional groups with a high functionality, which provides a high availability of reactive species, allowing easy cross-linking and / or a high cross-linking density of the curable composition. Non-limiting examples of suitable polyalkoxysilyl functional groups are triethoxysilyl groups or trimethoxysilyl groups. The alkoxy groups being methoxy groups or ethoxy groups provides a high atomefficiency in the formation of the solid electrolyte. The choice of alkoxy groups may also advantageously influence the reactivity of the functional groups, allowing for a more controlled curing process.

[0101] In particular embodiments, the polyalkoxy silyl functional group is selected from the group consisting of trialkoxy silyl (-SiJOR^OR^OR3)), which can be represented by Formula (VI); dialkoxy alkyl silyl (- Si(OR4)(OR5)(R6)), which can be represented by Formula (VII); monoalkoxy dialkyl silyl (-Si(OR7)(R8)(R9)), which can be represented by Formula (VIII); and combinations thereof:

[0102] (VI); (VII); (VIII) wherein R1, R2, R3, R4, R5, R6, R7, R8, R9are each independently alkyl, preferably a Ci-ioalkyl, preferably a Ci-8alkyl, preferably a Ci-4alkyl.

[0103] In preferred embodiments, the polyalkoxy silyl functional group is selected from the group consisting of trialkoxy silyl (-Si(OR1)(OR2)(OR3)), which can be represented by Formula (VI); dialkoxy alkyl silyl (- Si(OR4)(OR5)(R6)), which can be represented by Formula (VII); and combinations thereof, wherein Formula (VI) and Formula (VII) are as defined herein above.

[0104] Whenever the term "substituted" is used in the present invention, it is meant to indicate that one or more hydrogens on the atom indicated in the expression using "substituted" is replaced with a selection from the indicated group, provided that the indicated atom's normal valency is not exceeded, and that the substitution results in a chemically stable compound. Where groups can be substituted, such groups may be substituted with one or more, and preferably one, two or three substituents.

[0105] The term "alkyl" as a group or part of a group, refers to a hydrocarbyl group of formula CnH2n+i wherein n is a number greater than or equal to 1, with no site of unsaturation. Alkyl groups may be linear or branched and may be substituted as indicated herein. Generally, alkyl groups can comprise from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, more preferably from 1 to 6 carbon atoms, more preferably from 1 to 4 carbon atoms. When a subscript is used herein following a carbon atom, the subscript refers to the number of carbon atoms that the named group may contain. For example, the term "Ci.6alkyl", as a group or part of a group, refers to a hydrocarbyl group of formula CnH2n+i wherein n is a number ranging from 1 to 6. Thus, for example, "Ci.6alkyl" includes all linear or branched alkyl groups with between 1 and 6 carbon atoms, and thus includes methyl, ethyl, n-propyl, / -propyl, butyl, and its isomers (e.g., n-butyl, i- butyl, and t-butyl); pentyl and its isomers, hexyl, and its isomers, etc. For example, Ci.4alkyl includes all linear or branched alkyl groups having 1 to 4 carbon atoms, and thus includes for example methyl, ethyl, n-propyl, / -propyl, 2-methyl-ethyl, butyl, and its isomers (e.g., n-butyl, / -butyl, and t-butyl), and the like.

[0106] In particular embodiments, the term alkyl refers to Ci-i2a Ikyl (Ci-i2hydrocarbons), yet more in particular to Ci-ioalkyl (Ci-io hydrocarbons), yet more in particular to Ci.9alkyl (Ci.9hydrocarbons), yet more in particular to Ci-ealkyl (Ci-6 hydrocarbons) as further defined herein above. Non-limiting examples of alkyl include methyl, ethyl, 1-propyl (n-propyl), 2-propyl ( / Pr), 1-butyl, 2-methyl-l-propyl(i-Bu), 2-butyl (s-Bu), 2- dimethyl-2-propyl (t-Bu), 1-pentyl (n-pentyl), 2-pentyl, 3-pentyl, 2-methyl-2-butyl, 3-methyl-2-butyl, 3- methyl-l-butyl, 2-methyl-l-butyl, 1-hexyl, 2-hexyl, 3-hexyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4- methyl-2-pentyl, 3-methyl-3-pentyl, 2-methyl-3-pentyl, 2,3-dimethyl-2-butyl, 3,3-dimethyl-2-butyl, n- heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, and n-icosyl.

[0107] The term "hydroxyl" or "hydroxy" as used herein refers to the group -OH.

[0108] The term "alkoxy" or "alkyloxy", as a group or part of a group, refers to a group of formula -ORawherein Rais alkyl as defined herein. Non-limiting examples of suitable Ci.6alkoxy include methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy, and hexyloxy.

[0109] It should be understood that in the context of the formation of a cross-linked or cured polymer network as disclosed herein, alkoxy groups are reactive functional groups that can participate in the network formation. Alkyl groups are considered non-reactive functional groups under the process conditions as disclosed herein and typically do not participate in the network formation, resulting in unreacted, dangling chain ends within the polymeric structure.

[0110] In preferred embodiments, the polyalkoxy silyl functional group is a hydrolysable group. In other words, the alkoxy groups attached to the silicon atom can react with water, leading to the formation of a silanol group (Si-OH) and an alcohol condensate (ROH). Subsequent condensation reactions of the formed silanol groups may result in the formation of siloxane bonds (-Si-O-Si-).

[0111] The polyalkoxy silyl functional groups of the polyether compound may allow cross-linking by reacting between themselves and / or with the polyalkoxy silyl functional groups of the cross-linker. During crosslinking or curing, the metal salt (M+), and the optional ionically conductive compound, such as an ionic liquid, may be embedded in the three-dimensional network, thereby obtaining a solid electrolyte.

[0112] A skilled person will understand that the polyether compound and the cross-linker should have a number of alkoxy groups suitable for forming a polymer network of a suitable cross-linking degree. In a non-limiting exemplary embodiment, the polyether compound may comprise one trialkoxy silyl functional group (i.e., having three hydrolysable alkoxy groups) and the cross-linker may comprise two trialkoxy silyl functional groups (i.e., having six hydrolysable alkoxy groups). In another non-limiting exemplary embodiment, the polyether compound may comprise two trialkoxy silyl functional groups (i.e., having six hydrolysable alkoxy groups) and the cross-linker may comprise three trialkoxy silyl functional groups (i.e., having nine hydrolysable alkoxy groups). In yet another non-limiting exemplary embodiment, the polyether compound may comprise one dialkoxy alkyl silyl functional group (i.e., having two hydrolysable alkoxy groups) and the cross-linker may comprise three trialkoxy silyl functional groups (i.e., having nine hydrolysable alkoxy groups).

[0113] In some embodiments, the curable composition may comprise

[0114] • a polyether compound comprising one trialkoxy silyl functional group;

[0115] • a cross-linker comprising two trialkoxy silyl functional groups;

[0116] • a metal (M+) salt, preferably a lithium (Li+) salt;

[0117] • optionally, an ionically conductive compound; and

[0118] • a solvent comprising water and one or more alcohols.

[0119] In some embodiments, the curable composition may comprise

[0120] • a polyether compound comprising one trialkoxy silyl functional group;

[0121] • a cross-linker comprising two trialkoxy silyl functional groups and a metal ion (M+) chelating moiety; • a metal (M+) salt, preferably a lithium (Li+) salt;

[0122] • clay mineral particles;

[0123] • optionally, an ionically conductive compound; and

[0124] • a solvent comprising water and one or more alcohols.

[0125] In some embodiments, the curable composition may comprise

[0126] • a polyether compound comprising two trialkoxy silyl functional groups;

[0127] • a cross-linker comprising two trialkoxy silyl functional groups;

[0128] • a metal (M+) salt, preferably a lithium (Li+) salt;

[0129] • optionally, an ionically conductive compound; and

[0130] • a solvent comprising water and one or more alcohols.

[0131] In some embodiments, the curable composition may comprise

[0132] • a polyether compound comprising two trialkoxy silyl functional groups;

[0133] • a cross-linker comprising two trialkoxy silyl functional groups and a metal ion (M+) chelating moiety;

[0134] • a metal (M+) salt, preferably a lithium (Li+) salt;

[0135] • clay mineral particles;

[0136] • optionally, an ionically conductive compound; and

[0137] • a solvent comprising water and one or more alcohols.

[0138] In some embodiments, the curable composition may comprise

[0139] • a polyether compound comprising one trialkoxy silyl functional group;

[0140] • a cross-linker comprising three trialkoxy silyl functional groups;

[0141] • a metal (M+) salt, preferably a lithium (Li+) salt;

[0142] • optionally, an ionically conductive compound; and

[0143] • a solvent comprising water and one or more alcohols.

[0144] In some embodiments, the curable composition may comprise

[0145] • a polyether compound comprising one trialkoxy silyl functional group;

[0146] • a cross-linker comprising three trialkoxy silyl functional groups and a metal ion (M+) chelating moiety;

[0147] • a metal (M+) salt, preferably a lithium (Li+) salt;

[0148] • clay mineral particles;

[0149] • optionally, an ionically conductive compound; and Y1

[0150] • a solvent comprising water and one or more alcohols.

[0151] In some embodiments, the curable composition may comprise

[0152] • a polyether compound comprising two trialkoxy silyl functional groups;

[0153] • a cross-linker comprising three trialkoxy silyl functional groups;

[0154] • a metal (M+) salt, preferably a lithium (Li+) salt;

[0155] • optionally, an ionically conductive compound; and

[0156] • a solvent comprising water and one or more alcohols.

[0157] In some embodiments, the curable composition may comprise

[0158] • a polyether compound comprising two trialkoxy silyl functional groups;

[0159] • a cross-linker comprising three trialkoxy silyl functional groups and a metal ion (M+) chelating moiety;

[0160] • a metal (M+) salt, preferably a lithium (Li+) salt;

[0161] • clay mineral particles;

[0162] • optionally, an ionically conductive compound; and

[0163] • a solvent comprising water and one or more alcohols.

[0164] In some embodiments, the polyether compound is an organoalkoxysilane comprising one or more polyalkoxy silyl functional groups, such as one polyalkoxy silyl functional group or two polyalkoxy silyl functional groups, and ether bonds (-C-O-C-). Advantageously, the present process for producing a solid electrolyte provides that the at least one polyalkoxy silyl functional groups allow a polyether structure with a high ionic conductivity to be covalently incorporated into the solid electrolyte. This has the advantage that the present invention allows to introduce grafted polymeric structures both at the surface and in the bulk of the porous composite network, resulting in a more homogeneous distribution of inorganic segments (e.g., providing strength) and organic segments (e.g., providing flexibility, and optimizing the lithium-ion transport path) across and within the porous structure.

[0165] Preferably, the polyalkoxy silyl functional group is a functional end group. However, the present disclosure is not limited to polyether compounds comprising polyalkoxy silyl functional end groups.

[0166] The terms "functional end group", "reactive end group", "terminal reactive group", and "end group" as used herein interchangeably refer to a substituent or moiety that is positioned at an extremity of a macromolecule or oligomer molecule (e.g., a polyether compound as disclosed herein). This has the advantage that the number of function groups per polyether compound is easy to control and / or easy to install, as often the end groups of a polymer have a different reactivity compared to other groups in the polymer molecule.

[0167] In particular embodiments, the polyether compound may comprise one polyalkoxy silyl functional end group, preferably one trialkoxy functional end group.

[0168] In particular embodiments, the polyether compound may comprise two polyalkoxy silyl functional end groups, preferably two trialkoxy functional end groups.

[0169] In particular embodiments, the polyether compound may comprise repeating units of Formula (I) and / or Formula (II)

[0170] (ID wherein n and m are positive integers; preferably each independently ranging from 3 to 15000, or 3 to 10000, or 3 to 5000, or 3 to 1000, or 3 to 500, or 3 to 150. The term "positive integer" as used herein refers to integers with a value greater than zero.

[0171] It has been found that an ethylene oxide group and / or a tetramethylene oxide group advantageously provide a high conductivity for metal ions (M+).

[0172] Non-limiting suitable examples of a polyether compound as disclosed herein are (methoxy(polyethyleneoxy)propyl)triethoxysilane, (methoxy(polyethyleneoxy)propyl)trimethoxysilane, 2- (methoxypoly(ethylenoxy)6-9propyl)dimethylmethoxysilane, bis(methoxy(triethyleneoxy)propyl)tetramethyldisiloxane, bis(methoxy(triethyleneoxy)propyl)tetramethyldisiloxane, methoxy(triethyleneoxy)undecyltrimethoxysilane, methoxy(triethyleneoxy)undecyltriethoxysilane, ll-(2- methoxyethoxy)undecyltrimethoxysilane, ll-(2-methoxyethoxy)undecyltriethoxysilane,

[0173] (methoxytri(ethyleneoxy)propyl)hexamethyltrisiloxanylethyltriethoxysilane, 2-(methoxy(triethyleneoxy))- (ll-triethoxysilyl)undecanoate, bis(3-triethoxysilylpropyl)polyethylene oxide; commercially available from Gelest Inc. In preferred embodiments, the curable composition as disclosed herein may comprise at least 1.0 wt.%, or at least 2.0 wt.%, or at least 3.0 wt.%, or at least 4.0 wt.%, or at least 5.0 wt.% of polyether compound; with wt.% relative to the total weight of the curable composition.

[0174] In preferred embodiments, the curable composition as disclosed herein may comprise at most 50.0 wt.%, or at most 40.0 wt.%, or at most 35.0 wt.%, or at most 30.0 wt.%, or at most 25.0 wt.% of polyether compound; with wt.% relative to the total weight of the curable composition.

[0175] In preferred embodiments, the curable composition as disclosed herein may comprise between 1.0 and 50.0 wt.%, or between 1.0 and 40.0 wt.%, or between 1.0 and 35.0 wt.%, or between 1.0 and 30.0 wt.%, or between 2.0 and 30.0 wt.%, or between 3.0 and 30.0 wt.%, or between 4.0 and 30.0 wt.%, or between 5.0 and 30.0 wt.%, or between 5.0 and 25.0 wt.% of polyether compound; with wt.% relative to the total weight of the curable composition.

[0176] In some embodiments, the cross-linker may be an organoalkoxysilane comprising two or more polyalkoxy silyl functional groups, such as two polyalkoxy silyl functional groups or three polyalkoxy silyl functional groups. Preferably, the cross-linker does not comprise ether bonds.

[0177] Advantageously, the present process for producing a solid electrolyte provides that the at least two polyalkoxy silyl functional groups allow the formation of a highly cross-linked polymer network without decreasing, or even improving, the ionic conductivity of the solid electrolyte. Without wishing to be bound by theory, it is believed that a high degree of cross-linking may create a more interconnected structure, which can distribute stress more evenly and enhances the material's ability to withstand mechanical forces without deforming. Another advantage is that the herein produced solid electrolyte may have the ability to accommodate volume variations during charge / discharge cycling, such as those experienced when lithium is used as an anode.

[0178] In particular embodiments, the cross-linker may comprise at most two polyalkoxy silyl functional groups; and is preferably selected from the group consisting of bis(3-triethoxysilylpropyl)amine, 1,2- bis(triethoxysilyl)ethane, N,N'-bis-[(3-triethoxysilylpropyl)aminocarbonyl]polyethylene oxide, bis(3- triethoxysilylpropyl)carbonate, bis(triethoxysilylpropyl)disulfide, N,N'-bis-[(3- triethoxysilylpropyl)thiourea], bis(3-trimethoxysilylpropyl)-N-methylamine, N,N'-bis(2-hydroxyethyl)- N,N'-bis(trimethoxysilylpropyl)ethylenediamine; l,2-bis(trimethoxysilyl)decane; 1,2- bis(triethoxysilyl)ethane; l,8-bis(triethoxysilyl)octane, bis(trimethoxysilylethyl)benzene; bis(triethoxysilyl)methane; l-(triethoxysilyl)-2-(diethoxymethylsilylethane), and mixtures thereof. In particular embodiments, the cross-linker comprises at most three polyalkoxy silyl functional groups; and is preferably selected from the group consisting of l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine- 2,4,6(lh,3h,5h)-trione, tris(3-(trimethoxysilyl)propyl)amine, l,l,l,3-tris(3-(triethoxysilyl) propyl) urea, and mixtures thereof.

[0179] In particular embodiments, the cross-linker is selected from the group consisting of l,3,5-tris[3- (trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lh,3h,5h)-trione, tris(3-(trimethoxysilyl)propyl)amine, l,l,l,3-tris(3-(triethoxysilyl) propyl) urea, and mixtures thereof.

[0180] Advantageously, the above-listed cross-linkers provide a curable composition that is able to produce a highly cross-linked solid electrolyte with low brittleness, high elasticity and / or high strength, without hampering the diffusion of metal ions.

[0181] In particular embodiments, the cross-linker may comprise a metal ion (M+) chelating moiety. It has been found that the incorporation of a metal ion (M+) chelating moiety in the cross-linker, may establish a bridging moiety between the constituting polymer chains, which may increase the mobility of metal ions, thereby further increasing the conductivity of the solid electrolyte.

[0182] As used herein, the term metal ion (M+) chelating moiety, may refer to a part of the molecule that has the ability to chelate or to form a complex with the metal ion (M+). Other groups may be present in or attached to the metal ion (M+) chelating moiety, which are not necessarily involved with the chelation of the ion.

[0183] In some embodiments, the metal ion (M+) chelating moiety is a cyclic moiety or a macrocyclic moiety. These cyclic or macrocyclic moieties may provide a certain rigidity to the cross-linker or the formed solid electrolyte, which may increase the speed of the polymerisation reaction and / or improve the mechanical properties of the solid electrolyte.

[0184] In some embodiments, the metal ion (M+) chelating moiety may be a cyanurate, a crown ether, an azacrown ether, a thia-crown ether, a cryptand, preferably a cyanurate or a crown ether.

[0185] As used herein, the term cyanurate refers to derivatives of cyanuric acid, which is represented by the Equilibrium (I):

[0186]

[0187] Typically derivatization may occur on the nitrogen atoms of cyanuric acid. Hence a cyanurate may be represented by formula (IX): Wherein R10, R11, R12are polyalkoxy silyl functional group as defined herein, preferably wherein R10, R11, R12comprise at least two polyalkoxy silyl functional group. Cyanurate may have the ability of chelating metal ions, particularly lithium (Li+) ions.

[0188] In some embodiments, the crown ether may be a 12-crown-4 crown ether or a 15-crown-5 crown ether, preferably a 12-crown-4 crown ether. In some embodiments, the at least two polyalkoxy silyl functional groups of the cross-linker may be side chains on the metal ion (M+) chelating moiety. Advantageously, this ensures that the metal ion (M+) chelating moiety becomes part of the polymer network, which thereby may increase the mobility of metal ions trough the polymer network.

[0189] In some embodiments, the cross-linker may be a l,3,5-tris[3-(trialkoxysilyl)alkyl]-l,3,5-triazine- 2,4,6(lh,3h,5h)-trione.

[0190] As used herein, l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lh,3h,5h)-trione, also known as VPS, is a molecule which can be represented by formula (X)

[0191] l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6( lh,3h,5h)-trione has 26115-70-8 as CAS number.

[0192] A different name is tris[3-(trimethoxysilyl)propyl] isocyanurate and it is a cyanurate within the meaning of this application. l,3,5-tris[3-(triethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lh,3h,5h)-trione, is the ethoxylated version of the compound described above, and can be represented by formula (XI): l,3,5-tris[3-(triethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lh,3h,5h)-trione has 82194-46-5 as CAS number and is often called l,3,5-tris(triethoxysilylpropyl) isocyanurate; tris(3-triethoxysilylpropyl) isocyanurate. The compound is also a cyanurate within the meaning of this application.

[0193] In preferred embodiments, the curable composition as disclosed herein may comprise at least 0.5 wt.%, or at least 1.0 wt.%, or at least 1.5 wt.%, or at least 2.0 wt.%, or at least 2.5 wt.% of cross-linker; with wt.% relative to the total weight of the curable composition. In preferred embodiments, the curable composition as disclosed herein may comprise at most 30.0 wt.%, or at most 27.5 wt.%, or at most 25.0 wt.%, or at most 22.5 wt.%, or at most 20.0 wt.% of cross-linker; with wt.% relative to the total weight of the curable composition.

[0194] In preferred embodiments, the curable composition as disclosed herein may comprise between 0.5 and 30.0 wt.%, or between 0.5 and 27.5 wt.%, or between 0.5 and 25.0 wt.%, or between 1.0 and 25.0 wt.%, or between 1.5 and 25.0 wt.%, or between 2.0 and 25.0 wt.%, or between 2.5 and 25.0 wt.%, or between 2.5 and 22.5 wt.%, or between 2.5 and 20.0 wt.% of polyether compound; with wt.% relative to the total weight of the curable composition.

[0195] In particular embodiments, the metal (M+) salt as referred to herein may comprise Li+, Na+, Mg+, Ca+, Al+, and / or a combination thereof. Preferably the metal salt comprises Li+and / or Na+, which are industry standard for the manufacturing of a high energy solid-state battery. Additionally, a plurality of different metal salts may be used, for example, Li+and / or Na+.

[0196] In some embodiments, the lithium (Li+) salt may comprise Lithium bis(trifluoromethanesulfonyl)imide (LiFSI), Lithium bis(trifluoromethane)sulfonimide (LiTFSI), Lithium hexafluorophosphate (LiPF6), Lithium tetrafluoroborate (LiBF4), Lithium bis(oxalato)borate (LiBOB), Lithium difluoro(oxalate)borate (LiODFB), Lithium nitrate (LiNO3), Lithium perchlorate (LiCIO4), any substitutions known in the art, and / or any combinations thereof. Each of the listed Li+salts can be used alone, in combination with other (unlisted) metal salts, or included as an additive. LiTFSI is preferred because it is more chemically stable in a(n) (organic) solvent. Additionally, a plurality of different metal salts may be used, for example, LiFSI and LiTFSI. In some embodiments, the sodium (Na+) salt may comprise Sodium bis(trifluoromethanesulfonyl)imide (NaFSI), Sodium bis(trifluoromethane)sulfonimide (NaTFSI), Sodium hexafluorophosphate (NaPF6), Sodium tetrafluoroborate (NaBF4), Sodium bis(oxalato)borate (NaBOB), Sodium difluoro(oxalate)borate (NaODFB), Sodium nitrate (NaNO3), any substitutions known in the art, and / or a combination thereof. NaTFSI is preferred because it is more chemically stable in an organic solvent. Additionally, a plurality of different metal salts may be used, for example, NaFSI and NaTFSI.

[0197] In some embodiments, the curable composition as disclosed herein may comprise at least 1.0 wt.%, or at least 2.0 wt.%, or at least 3.0 wt.%, or at least 4.0 wt.%, or at least 5.0 wt.% of metal (M+) salt; with wt.% relative to the total weight of the curable composition.

[0198] In some embodiments, the curable composition as disclosed herein may comprise at most 35.0 wt.%, or at most 30.0 wt.%, or at most 25.0 wt.%, or at most 20.0 wt.%, of metal (M+) salt; with wt.% relative to the total weight of the curable composition. In some embodiments, the curable composition as disclosed herein may comprise between 1.0 and 35.0 wt.%, or between 1.0 and 30.0 wt.%, or between 1.0 and 30.0 wt.%, or between 1.0 and 25.0 wt.%, or between 2.0 and 25.0 wt.%, or between 3.0 and 25.0 wt.%, or between 4.0 and 25.0 wt.%, or between 5.0 and 25.0 wt.%, or between 5.0 and 20.0 wt.% of metal (M+) salt; with wt.% relative to the total weight of the curable composition.

[0199] In particular embodiments, the curable composition as disclosed herein further comprises an ionically conductive compound. The ionically conductive compound has been found to further increase the ionic conductivity and metal ion transference number of the solid electrolyte as disclosed herein. This advantageously reduces or even avoids dendrite formation during operation. In a preferred embodiments, liquid additives with low flammability are included that can present high dielectric constant and lead to strong dissociation of the metal salts due to the strong interaction between strongly electronegative groups of the liquid additives and ions, thus providing high ionic conductivity for the solid electrolyte. Nevertheless, the addition of an ionically conductive compound is optional because the polyether compound as disclosed herein may advantageously already provide a solid electrolyte with desirable ionic conductivity.

[0200] In some embodiments, the ionically conductive compound is selected from the group consisting of: 1- Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIFSI), l-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI), l-Ethyl-3-methylimidazolium fluorosulfonyl (trifluoromethanesulfonyl)imide (EMIFTFSI), l-Ethyl-3-methylimidazolium trifluoromethanesulfonate (EMIOTf), Butyltrimethylammonium bis(trifluoromethylsulfonyl)imide (BMATFSI), l-Ethyl-3- methylimidazolium bis(pentafluoroethylsulfonyl)imide (EMIBeti), l-Ethyl-3-methylimidazolium dicyanamide (EMIDCA), l-Ethyl-3-methylimidazolium diethylphosphate (EMIDEP), l-Butyl-3- methylimidazolium bis(fluorosulfonyl)imide (BMIFSI), l-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMITFSI), l-Butyl-3-methylimidazolium fluorosulfonyl (trifluoromethanesulfonyl)imide (BMIFTFSI) l-Butyl-3-methylimidazolium trifluoromethanesulfonate (BMIOTf), l-Butyl-3-methylimidazolium bis(pentafluoroethylsulfonyl)imide (BMIBeti), 1-Butyl-l- methylpyrrolidinium bis(fluorosulfonyl)imide (BMPFSI), 1-Butyl-l-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPTFSI), 1-Butyl-l-methylpyrrolidinium fluorosulfonyl (trifluoromethanesulfonyl)imide (BMPFTFSI), 1-Butyl-l-methylpyrrolidinium trifluoromethanesulfonate (BMPOTf), 1-Butyl-l-methylpyrrolidinium bis(pentafluoroethylsulfonyl)imide (BMPBeti), 1-Methyl-l- pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyrl5TFSI), 1-Methyl-l-pentylpyrrolidinium fluorosulfonyl (trifluoromethanesulfonyl)imide (Pyrl5FTFSI), 1-Methyl-l-pentylpyrrolidinium trifluoromethanesulfonate (Pyrl5OTf), 1-Methyl-l-pentylpyrrolidinium bis(pentafluoroethylsulfonyl)imide (Pyrl5Beti), tetraethylene glycol dimethyl ether (TEGDM), triethylsulfonium bis(trifluoromethanesulfonyl)imide (TESTFSI), tetrabutylammonium bis(trifluoromethane)sulfonylimide (TBATFSI), and mixtures thereof.

[0201] In some embodiments, the ionically conductive compound is selected from the group consisting of: 1- Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIFSI), l-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI), Butyltrimethylammonium bis(trifluoromethylsulfonyl)imide (BMATFSI), l-Butyl-3-methylimidazolium bis(fluorosulfonyl)imide (BMIFSI), l-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMITFSI), 1-Butyl-l-methylpyrrolidinium bis(fluorosulfonyl)imide (BMPFSI), 1-Butyl-l-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPTFSI), 1-Butyl-l- methylpyrrolidinium fluorosulfonyl (trifluoromethanesulfonyl)imide (BMPFTFSI), 1-Methyl-l- pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyrl5TFSI), tetraethylene glycol dimethyl ether (TEGDM), triethylsulfonium bis(trifluoromethanesulfonyl)imide (TESTFSI), tetrabutylammonium bis(trifluoromethane)sulfonylimide (TBATFSI), and mixtures thereof.

[0202] In some embodiments, the ionically conductive compound is selected from the group consisting of: 1- Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI), Butyltrimethylammonium bis(trifluoromethylsulfonyl)imide (BMATFSI), l-Butyl-3-methylimidazolium bis(fluorosulfonyl)imide (BMIFSI), l-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMITFSI), 1-Butyl-l- methylpyrrolidinium bis(fluorosulfonyl)imide (BMPFSI), 1-Methyl-l-pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyrl5TFSI), tetraethylene glycol dimethyl ether (TEGDM), N- methylacetamide, tetraethylene glycol dimethyl ether and mixtures thereof.

[0203] In some embodiments, the curable composition as disclosed herein may comprise at least 0.5 wt.%, or at least 1.0 wt.%, or at least 1.5 wt.%, or at least 2.0 wt.%, or at least 2.5 wt.% of ionically conductive compound; with wt.% relative to the total weight of the curable composition.

[0204] In some embodiments, the curable composition as disclosed herein may comprise at most 30.0 wt.%, or at most 27.5 wt.%, or at most 25.0 wt.%, or at most 22.5 wt.%, or at most 20.0 wt.% of ionically conductive compound; with wt.% relative to the total weight of the curable composition.

[0205] In some embodiments, the curable composition as disclosed herein may comprise between 0.5 and 30.0 wt.%, or between 0.5 and 27.5 wt.%, or between 0.5 and 25.0 wt.%, or between 1.0 and 25.0 wt.%, or between 1.5 and 25.0 wt.%, or between 2.0 and 25.0 wt.%, or between 2.5 and 25.0 wt.%, or between 2.5 and 22.5 wt.%, or between 2.5 and 20.0 wt.% of ionically conductive compound; with wt.% relative to the total weight of the curable composition.

[0206] In some embodiments, the curable composition may further comprise a compound selected from the group consisting of tetraalkoxy silane, trialkoxy alkyl silane, dialkoxy dialkyl silane, alkoxy trialkyl silane, and mixtures thereof. It has been found that the addition of one or more of the silane compounds as listed herein may enable the formation of a cured polymer network with controlled porosity and microstructure. In addition, another advantage is that it increases the thermal stability of the resulting solid electrolyte.

[0207] In some embodiments, the curable composition may further comprise tetraalkoxy silane, and preferably wherein the tetraalkoxy silane is selected from the group consisting of tetraethoxy silane, tetramethoxy silane, tetrapropoxy silane, tetrabutoxy silane, and mixtures thereof. Said compounds are readily available, making the present process more cost-effective, and may enable rapid curing and solidification of the curable composition.

[0208] In particular embodiments, the curable composition may further comprise clay mineral particles. Clay minerals are naturally occurring minerals that are abundant in the Earth's crust. They belong to the phyllosilicate group (i.e., hydrous aluminium phyllosilicates) and are characterized by their layered and crystalline structure. It has been found that clay minerals of a smaller particle size, preferably nanoparticles with a size ranging between 1.0 and 100.0 nm, may provide a higher compatibility between the cured polymer network and the clay mineral particles.

[0209] Advantageously, it has been found herein that the inclusion of clay mineral particles may further enhance the mechanical strength and conductivity performance of the resulting solid electrolyte.

[0210] Another advantage of the present clay mineral particles may be the provision of a solid electrolyte with a higher electrochemical stability window and thermal stability, thereby preventing creep under pressure.

[0211] In preferred embodiments, the clay mineral particles may be nanoparticles with a fibrous or tubular structure. This has the advantage that said nanoparticles may simultaneously reinforce the cured polymer network and provide a high surface area for interaction with the metal (M+) salt, which can result in an increase in mechanical strength and ionic conductivity of the solid electrolyte.

[0212] In certain embodiments, the clay mineral particles may comprise (nano)structures having an elongated shape, such as a fibrous or a needle-like structure. This elongated shape may improve its absorbent and binding properties due to the increased surface area available for interactions. Alternatively, the clay mineral particles can comprise individual nanoparticles that align to an elongated structure. Preferably, the elongated shapes may include nanowires, nanofibers, nanowires, nanotubes, and / or nanorods. In certain embodiments, the clay mineral particles may comprise (nano)structures comprising of rolled or tubular layers, advantageously with a hollow central core or lumen. The external and internal surfaces of the clay mineral particles can be functionalized or modified to enhance compatibility with specific substances such as described in a later embodiment.

[0213] In certain embodiments, the clay mineral particles may comprise (nano)structures with a tubular shape having a negatively charged exterior and a positively charged interior. Without wishing to be bound by theory, it has been found that the negatively charged exterior of the clay mineral particles is capable of interacting with the metal salt embedded in the cured polymer network. As a result, the clay mineral particles may aid in the dissociation of the metal salt and improve the ionic conductivity of the solid electrolyte. As such, the electrochemical and thermal stability can be enhanced by adding clay mineral particles to the solid electrolyte.

[0214] In certain embodiments, the clay mineral particles comprise (nano)structures with a (nano)tubular shape having a hollow interior. Advantageously, the (nano)tubular shape consists of a plurality of rolled layers wherein each layer can comprise at least two different materials. For example, the clay mineral tubular shape may be comprised of rolled alumina and silica layers, the layers may be alternating or successive layers.

[0215] In certain embodiments, the clay mineral particles are selected from the group consisting of palygorskite, attapulgite, kaolin, smectite, illite, chlorite, sepiolite, vermiculite, and mixtures thereof; preferably palygorskite, kaolin and / or attapulgite.

[0216] In certain embodiments the solid electrolyte may comprise halloysite nanotubes (HNT). As used herein, halloysite nanotubes refers to a tubular 3D nanostructure having oppositely charged surfaces, more specifically, a negatively charged external surface, for example silica surface, and a positively charged interior surface, for example aluminol surface. In a preferred embodiment, HNT comprises aluminosilicate (AI2Si2Os(OH)4), preferably from natural nano-clay.

[0217] Another advantage of the clay mineral particles as disclosed herein is that the anions of the metal (M+) salt may be immobilized, which may lead to an increase of lithium-ion transference number (t i+) and a reduction in polarization, thereby resulting in a homogeneous lithium deposition and dissolution. In particular, without wishing to be bound by theory, it appears that the oppositely charged surfaces of the clay mineral particles can separate lithium salts into lithium cations that are absorbed on the negatively charged outer silica surface, and anions may be accommodated on the positively charged inner surface. So, an ordered 3D structure for free lithium-ion transport with shorten the distance of free lithium ions transfer, lower ionic coupling and provide a high-speed freeway for lithium-ion transport. Thus improving the ionic conductivity and the lithium-ion transference number of the electrolyte. Additional advantages conferred by the clay mineral particles can include an enhanced mechanical strength, high electrochemical stability window and thermal stability preventing creep under pressure.

[0218] In some embodiments, the curable composition as disclosed herein may comprise at least 0.5 wt.%, or at least 1.0 wt.%, or at least 1.5 wt.%, or at least 2.0 wt.%, or at least 2.5 wt.% of clay mineral particles; with wt.% relative to the total weight of the curable composition.

[0219] In some embodiments, the curable composition as disclosed herein may comprise at most 20.0 wt.%, or at most 17.5 wt.%, or at most 15.0 wt.%, or at most 10.0 wt.% of clay mineral particles; with wt.% relative to the total weight of the curable composition.

[0220] In some embodiments, the curable composition as disclosed herein may comprise between 0.5 and 20.0 wt.%, or between 0.5 and 17.5 wt.%, or between 0.5 and 15.0 wt.%, or between 1.0 and 15.0 wt.%, or between 1.5 and 15.0 wt.%, or between 2.0 and 15.0 wt.%, or between 2.5 and 15.0 wt.%, or between 2.5 and 10.0 wt.% of clay mineral particles; with wt.% relative to the total weight of the curable composition. In some embodiments, the curable composition may further comprise a catalyst. Preferably, the catalyst is a phosphoric acid orga nocatalyst, more preferably a phosphoric acid diester. In some embodiments, the catalyst is selected from the group comprising dibutyl phosphate (DBuP), diphenyl phosphate (DPP), 1,1'- binaphthyl-2,2'-diyl hydrogen phosphate (BNPH) or mixtures thereof. It has been found that such catalyst results in a fast polymerisation reaction.

[0221] In some embodiments, the curable composition may further comprise clay mineral particles and a dispersing agent. The term "dispersing agent" (synonymous with diffusing agent, dispersant, dispersing additive, or wetting agent) as used herein refers to a substance or compound that facilitates the dissolution of an inorganic filler in the liquid mixture by reducing the interfacial tension between two phases or components. Moreover, it has now been found that the addition of a dispersing agent, specifically a phosphate-based dispersing agent, can significantly improve the chemical compatibility between the inorganic filler and the network structure of the solid electrolyte.

[0222] Homogeneous dispersion or distribution of the inorganic filler in the three-dimensional network by the dispersing agent has the advantage that the mechanical integrity, chemical stability, and thermal resistance of the resulting solid electrolyte can be improved without compromising (or even improving) ionic conductivity. In preferred embodiments, the dispersing agent may be a phosphate-based dispersing agent comprising at least one phosphate (e.g., orthophosphate, dihydrogen phosphate, or hydrogen phosphate) anion. Said phosphate-based dispersing agent may be commercially available as salt(s) comprising at least one phosphate anion.

[0223] In more preferred embodiments, the phosphate-based dispersing agent may be a phosphate salt. Preferably, said phosphate salt is a monovalent or multivalent phosphate salt, such as a divalent, trivalent, tetravalent phosphate salt. Advantageously, multivalent interactions of the phosphate salt with the surface of other materials, such as an inorganic filler as disclosed herein, may modify the surface properties of said inorganic filler to improve heat resistance, mechanical stability and chemical compatibility.

[0224] In some embodiments, the phosphate salt may comprise an alkali metal ion (cation) selected from the group consisting of lithium, sodium, potassium, rubidium, and mixtures thereof.

[0225] In some embodiments, the phosphate salt may comprise an alkaline earth metal ion (cation) selected from the group consisting of beryllium, magnesium, calcium, strontium, barium, and mixtures thereof.

[0226] In some embodiments, the phosphate salt may comprise an ammonium ion (NH4+, cation) and / or an organoammonium ion (cation).

[0227] In preferred embodiments, the phosphate-based dispersing agent may be a polyphosphate salt. The term "polyphosphate" as used herein refers to phosphate anions which have been polymerized by dehydration to form a polymer of the phosphate anion. The term "polyphosphate salt" as described herein refers to said polymer of the phosphate anion with one or more counterion. Polyphosphates can exist as linear or cyclic materials or mixtures thereof. Preferred polyphosphates used herein are linear materials comprising only low levels of cyclic materials. Polyphosphates can also be characterized by the average anion chain length of the polymer anion. Therefore, and in some embodiments, the polyphosphate salt may comprise a plurality of polyphosphate chains having a backbone comprising oxygen-phosphate bonds having "n" phosphate units, with "n" being a positive integer.

[0228] In some embodiments, each phosphate unit may include a counterion, e.g. an alkali metal cation, an alkaline earth metal cation, an ammonium cation or an organoammonium cation, as described above.

[0229] In some embodiments, the amount of phosphate units "n" of the polyphosphate salt as described herein may be at least 10.0, such as between 10.0 and 40.0, or between 15.0 and 30.0 or between 18.0 and 30.0, and combinations thereof.

[0230] The advantage of the polyphosphate salt in particular is that it can modify the surface properties of the inorganic filler to improve the dispersion or distribution of said filler in the network. Moreover, it can simultaneously activate the ionic conductivity of the inorganic filler, creating continuous ion channels for alkali metal ions in the bulk of the solid electrolyte, which may significantly improve ion transportation. Hence, when applied in an electrochemical energy storage device, said solid electrolyte may provide an enhanced charge and discharge rate.

[0231] In particular embodiments, the phosphate-based dispersing agent may be selected from the group consisting of monolithium phosphate, dilithium phosphate, trilithium phosphate, monolithium diphosphate, dilithium diphosphate, trilithium diphosphate, tetralithium diphosphate, lithium triphosphate, lithium tetraphosphate, lithium metaphosphate, lithium trimetaphosphate, lithium hexametaphosphate, lithium pyrophosphate, dilithium pyrophosphate, lithium polyphosphate, monosodium phosphate, disodium phosphate, trisodium phosphate, monosodium diphosphate, disodium diphosphate, trisodium diphosphate, tetrasodium diphosphate, sodium triphosphate, sodium tetraphosphate, sodium metaphosphate, sodium trimetaphosphate, sodium hexametaphosphate, sodium pyrophosphate, disodium pyrophosphate, sodium polyphosphate, monopotassium phosphate, dipotassium phosphate, tripotassium phosphate, monopotassium diphosphate, dipotassium diphosphate, tripotassium diphosphate, tetra potassium diphosphate, potassium triphosphate, potassium tetraphosphate, potassium metaphosphate, potassium trimetaphosphate, potassium hexametaphosphate, potassium pyrophosphate, dipotassium pyrophosphate, potassium polyphosphate hydrates thereof and / or mixtures thereof; preferably wherein the phosphate-based dispersing agent is lithium polyphosphate, sodium polyphosphate, or potassium polyphosphate.

[0232] In particular embodiments, the phosphate-based dispersing agent may be selected from the group consisting of monosodium phosphate, disodium phosphate, trisodium phosphate, monosodium diphosphate, disodium diphosphate, trisodium diphosphate, tetrasodium diphosphate, sodium triphosphate, sodium tetraphosphate, sodium metaphosphate, sodium trimetaphosphate, sodium hexametaphosphate, sodium pyrophosphate, disodium pyrophosphate, sodium polyphosphate, monopotassium phosphate, dipotassium phosphate, tripotassium phosphate, monopotassium diphosphate, dipotassium diphosphate, tripotassium diphosphate, tetrapotassium diphosphate, potassium triphosphate, potassium tetraphosphate, potassium metaphosphate, potassium trimetaphosphate, potassium hexametaphosphate, potassium pyrophosphate, dipotassium pyrophosphate, potassium polyphosphate hydrates thereof and / or mixtures thereof; preferably wherein the phosphate-based dispersing agent is sodium polyphosphate or potassium polyphosphate. In particular embodiments, the phosphate-based dispersing agent may be selected from the group consisting of monosodium phosphate, disodium phosphate, trisodium phosphate, monosodium diphosphate, disodium diphosphate, trisodium diphosphate, tetrasodium diphosphate, sodium triphosphate, sodium tetraphosphate, sodium metaphosphate, sodium trimetaphosphate, sodium hexametaphosphate, sodium pyrophosphate, disodium pyrophosphate, sodium polyphosphate; preferably wherein the phosphate-based dispersing agent is sodium polyphosphate or sodium hexametaphosphate.

[0233] In some embodiments, the step of curing the curable composition may be performed for at least 15 minutes, preferably at least 30 minutes, preferably at least 45 minutes, preferably at least 60 minutes.

[0234] In some embodiments, the step of curing the curable composition may be performed at a temperature of between at least 0 °C and at most 70 °C, or between at least 5 °C and at most 70 °C, or between at least 5 °C and at most 60 °C, or between at least 10 °C and at most 60 °C, or between at least 15 °C and at most 60 °C, or between at least 20 °C and at most 60 °C, or between at least 20 °C and at most 50 °C. The listed temperatures can decrease the time needed for polymer network to form, although lower temperatures can be considered still.

[0235] As mentioned before, curing of the curable composition is preferably obtained by a sol-gel process, in particular by reacting the polyether compound and the cross-linker (comprising a specified amount of polyalkoxy silyl functional groups) in the presence of a solvent. A "sol-gel process" as referred to herein involves the conversion of reactive compounds (e.g., the polyether compound and the cross-linker) into a colloidal suspension (sol), which acts as a precursor for an integrated network (gel). In particular, the herein disclosed sol-gel process is a wet-crosslinking technique that may be initiated by hydrolysis (and / or alcoholysis) of a polyalkoxy silyl functional group in the presence of a solvent comprising water, and preferably one or more compounds capable of mixing the water, polyether compound, and cross-linker.

[0236] In particular embodiments, the solvent comprises an amount of water sufficient for modifying the reactivity of at least a portion of the polyalkoxy silyl functional groups comprised in the curable composition, preferably by hydrolyzing at least a portion of the polyalkoxy silyl functional groups.

[0237] Advantageously, the solvent may further aid in the mixing and dispersion of the compounds comprised in the curable composition as well as provide a curable composition having a desirable viscosity for easier handling and processing.

[0238] In particular embodiments, the solvent comprises water and one or more alcohols. Suitable alcohols include isopropanol, ethanol, l-methoxy-2-propanol, and mixtures thereof. In some embodiments, the weight ratio of solvent to polyether compound is at least 1.0, or at least 2.0, or at least 3.0, or at least 4.0, or at least 5.0.

[0239] In some embodiments, after the curing step, the solid electrolyte can be dried. The drying can be performed by a (classic) drying process and / or an ageing process, preferably an ageing process followed by (classic) drying process. Typically, ageing is intended to further increase the degree of condensation (and for the present embodiment, the degree of case cross-linking) after reaching the liquid-to-solid transition. For example, the obtained solid electrolyte can be dried, using a vacuum dryer under the conditions of a pressure of 0.1 to 200 Pa and a temperature of 15 to 100 °C (ambient temperature). Optionally, a pre-drying process may additionally be carried out before the drying process to reduce occurrence of bumping and generation of air bubbles during the vacuum drying. In the pre-drying process, the obtained solid electrolyte is heated, for example, using a hot plate provided on a local exhaust system under the conditions of atmospheric pressure and a temperature of 15 to 90 °C (surface temperature of the hot plate). Most of the solvent contained in the solid electrolyte can be evaporated by the pre-drying process.

[0240] In particular embodiments, the process as disclosed herein comprises drying the solid electrolyte until the water content is less than 2000 ppm, or less than 1500 ppm, or less than 1250 ppm, or less than 1000 ppm, or less than 900 ppm, or less than 800 ppm, or less than 700 ppm, or less than 600 ppm, or less than 500 ppm, or less than 100 ppm, for example 50 ppm or 10 ppm.

[0241] In exemplary embodiments, the process as disclosed herein may comprise the steps of providing a curable composition, the curable composition comprising

[0242] • a polyether compound comprising at least one polyalkoxy silyl functional group;

[0243] • a cross-linker comprising three trialkoxy silyl functional groups;

[0244] • a lithium (Li+) salt;

[0245] • optionally, an ionically conductive compound; and

[0246] • a solvent comprising water and one or more alcohols; curing the curable composition, thereby obtaining the solid electrolyte; drying the solid electrolyte.

[0247] In exemplary embodiments, the process as disclosed herein may comprise the steps of providing a curable composition, the curable composition comprising

[0248] • a polyether compound comprising at least one polyalkoxy silyl functional group; • a cross-linker comprising three trialkoxy silyl functional groups and a metal ion (M+) chelating moiety;

[0249] • a lithium (Li+) salt;

[0250] • optionally, an ionically conductive compound; and

[0251] • a solvent comprising water and one or more alcohols; curing the curable composition, thereby obtaining the solid electrolyte; drying the solid electrolyte.

[0252] In some embodiments, the curable composition as disclosed herein may comprise

[0253] 1.0 to 50.0 wt.% of polyether compound;

[0254] 0.5 to 30.0 wt.% of cross-linker;

[0255] 1.0 to 35.0 wt.% of lithium (Li+) salt;

[0256] 0.5 to 60.0 wt.% of ionically conductive compound;

[0257] 10.0 to 65.0 wt.% of solvent comprising water; and preferably wherein the solvent comprises at least 30.0 wt.% of water; with wt.% relative to the total weight of the curable composition.

[0258] In some embodiments, the curable composition as disclosed herein may comprise

[0259] 1.0 to 25.0 wt.% of polyether compound;

[0260] 0.5 to 15.0 wt.% of cross-linker;

[0261] 1.0 to 15.0 wt.% of lithium (Li+) salt;

[0262] 0.5 to 35.0 wt.% of ionically conductive compound;

[0263] 10.0 to 50.0 wt.% of solvent comprising water; with wt.% relative to the total weight of the curable composition.

[0264] In exemplary embodiments, the process as disclosed herein may comprise the steps of providing a curable composition, the curable composition comprising

[0265] • a polyether compound comprising at least one polyalkoxy silyl functional group;

[0266] • a cross-linker comprising three trialkoxy silyl functional groups;

[0267] • a lithium (Li+) salt;

[0268] • clay mineral particles;

[0269] • optionally, an ionically conductive compound; and

[0270] • a solvent comprising water and one or more alcohols; curing the curable composition, thereby obtaining the solid electrolyte; drying the solid electrolyte. In exemplary embodiments, the process as disclosed herein may comprise the steps of providing a curable composition, the curable composition comprising

[0271] • a polyether compound comprising at least one polyalkoxy silyl functional group;

[0272] • a cross-linker comprising three trialkoxy silyl functional groups and a metal ion (M+) chelating moiety;

[0273] • a lithium (Li+) salt;

[0274] • clay mineral particles;

[0275] • optionally, an ionically conductive compound; and

[0276] • a solvent comprising water and one or more alcohols; curing the curable composition, thereby obtaining the solid electrolyte; drying the solid electrolyte.

[0277] In some embodiments, the curable composition as disclosed herein may comprise

[0278] 1.0 to 50.0 wt.% of polyether compound;

[0279] 0.5 to 30.0 wt.% of cross-linker;

[0280] 1.0 to 35.0 wt.% of lithium (Li+) salt;

[0281] 0.5 to 20.0 wt.% of clay mineral particles

[0282] 0.5 to 60.0 wt.% of ionically conductive compound;

[0283] 10.0 to 65.0 wt.% of solvent comprising water; and preferably wherein the solvent comprises at least 30.0 wt.% of water; with wt.% relative to the total weight of the curable composition.

[0284] In some embodiments, the curable composition as disclosed herein may comprise

[0285] 1.0 to 25.0 wt.% of polyether compound;

[0286] 0.5 to 10.0 wt.% of cross-linker;

[0287] 1.0 to 15.0 wt.% of lithium (Li+) salt;

[0288] 0.5 to 20.0 wt.% of clay mineral particles

[0289] 0.5 to 20.0 wt.% of ionically conductive compound;

[0290] 10.0 to 50.0 wt.% of solvent comprising water; and preferably wherein the solvent comprises at least 30.0 wt.% of water; with wt.% relative to the total weight of the curable composition.

[0291] In exemplary embodiments, the process as disclosed herein may comprise the steps of providing a curable composition, the curable composition comprising

[0292] • a polyether compound comprising at least one polyalkoxy silyl functional group;

[0293] • a cross-linker comprising three trialkoxy silyl functional groups; • a lithium (Li+) salt;

[0294] • clay mineral particles;

[0295] • a tetraalkoxy silane;

[0296] • optionally, an ionically conductive compound; and

[0297] • a solvent comprising water and one or more alcohols; curing the curable composition, thereby obtaining the solid electrolyte; drying the solid electrolyte.

[0298] In exemplary embodiments, the process as disclosed herein may comprise the steps of providing a curable composition, the curable composition comprising

[0299] • a polyether compound comprising at least one polyalkoxy silyl functional group;

[0300] • a cross-linker comprising three trialkoxy silyl functional groups and a metal ion (M+) chelating moiety;

[0301] • a lithium (Li+) salt;

[0302] • clay mineral particles;

[0303] • a tetraalkoxy silane;

[0304] • optionally, an ionically conductive compound; and

[0305] • a solvent comprising water and one or more alcohols; curing the curable composition, thereby obtaining the solid electrolyte; drying the solid electrolyte.

[0306] In some embodiments, the curable composition as disclosed herein may comprise

[0307] 1.0 to 50.0 wt.% of polyether compound;

[0308] 0.5 to 30.0 wt.% of cross-linker;

[0309] 1.0 to 35.0 wt.% of metal (M+) salt; preferably lithium (Li+) salt;

[0310] 0.5 to 20.0 wt.% of clay mineral particles

[0311] 0.5 to 20.0 wt.% of tetraalkoxy silane;

[0312] 0.5 to 60.0 wt.% of ionically conductive compound;

[0313] 10.0 to 65.0 wt.% of solvent comprising water; and preferably wherein the solvent comprises at least 30.0 wt.% of water; with wt.% relative to the total weight of the curable composition.

[0314] In some embodiments, the curable composition as disclosed herein may comprise

[0315] 1.0 to 15.0 wt.% of polyether compound;

[0316] 0.5 to 10.0 wt.% of cross-linker; 1.0 to 15.0 wt.% of metal (M+) salt; preferably lithium (Li+) salt;

[0317] 0.5 to 10.0 wt.% of clay mineral particles

[0318] 0.5 to 10.0 wt.% of tetraalkoxy silane;

[0319] 0.5 to 30.0 wt.% of ionically conductive compound;

[0320] 10.0 to 50.0 wt.% of solvent comprising water; and preferably wherein the solvent comprises at least 30.0 wt.% of water; with wt.% relative to the total weight of the curable composition.

[0321] In this way, a solid electrolyte is obtained that can provide flexibility and reduce the brittleness that is specific to pure inorganic glasses. This combination could help prevent stress cracking during the curing process allowing the possibility of coating on substrates of over large areas. In comparison, for silica particles, such as those described in the art, any additional polymers are only grafted at the surface of the composite network, hence essentially forming a "coating" on the inside of the pores of the composite network.

[0322] Accordingly the present disclosure further encompasses a solid electrolyte, preferably for an electrochemical energy storage device, obtained or obtainable by means of the process for producing a solid electrolyte as disclosed herein.

[0323] Another aspect of the present disclosure relates to a solid electrolyte, for an electrochemical energy storage device, comprising a cured polymer network; wherein the cured polymer network comprises polyether chains; metal ions (M+), preferably lithium ions (Li+); optionally, an ionically conductive compound; cross-links having at least two bridging moieties; wherein each bridging moiety is independently selected from the group consisting of Formula (III), Formula (IV), and Formula (V)

[0324]

[0325] In particular embodiments, the solid electrolyte comprises: a polymeric matrix comprising polyether chains; metal ions (M+), preferably lithium ions (Li+); metal ion (M+) chelating moieties; clay mineral particles; optionally, an ionically conductive compound; cross-links containing siloxane (-Si-O-Si-) bonds.

[0326] It should be noted that (preferred) embodiments and associated advantages of the process for producing a solid electrolyte according to an aspect of the present disclosure are also (preferred) embodiments of the solid electrolyte according to an aspect of the present disclosure and vice versa.

[0327] In particular embodiments, the cured polymer network may comprise a metal ion (M+) chelating moiety, and preferably wherein the metal ion chelating moiety is a cyclic moiety or a macrocyclic moiety. It has been found that a covalently bonded or covalently incorporated metal ion (M+) chelating moiety in the cured polymer network may advantageously improve the ionic conductivity of the solid electrolyte.

[0328] In preferred embodiments, the polyether chains are connected to one another by bridging moieties of Formula (III), Formula (IV), and / or Formula (V) as defined herein above. It has been found that by covalently bonding or covalently integrating the polyether chains in the three-dimensional polymer network, a solid electrolyte may be provided which has a more homogenous ionic conductivity and decreased polarization. In particular embodiments, the cured polymer network further comprises clay mineral particles; preferably wherein the clay mineral particles are selected from the group consisting of palygorskite, attapulgite, kaolin, smectite, illite, chlorite, sepiolite, vermiculite, and mixtures thereof; preferably palygorskite, kaolin and / or attapulgite; and preferably wherein the clay mineral particles comprise halloysite nanotubes (HNT) comprising aluminosilicate (AI2Si2O5(OH)4).

[0329] In some embodiments, the solid electrolyte has an ionic conductivity of at least 0.80, or at least 0.85, or at least 0.90 mS / cm at 20 °C as determined according to the method described herein in the example section.

[0330] In some embodiments, the solid electrolyte has a loss factor (tan delta) of at most 0.150, or at most 0.140, or at most 0.130, or at most 0.120, or at most 0.110, or at most 0.100, or at most 0.090 at 20 °C and a shear strain of 1% as determined according to the method described herein in the example section.

[0331] In some embodiments, the solid electrolyte has an electrochemical stability window of at least 5.0 V as determined according to the method described herein in the example section.

[0332] As mentioned above, the present solid electrolyte is particularly suitable for application in an electrochemical energy storage device. Accordingly, the present disclosure further encompasses the use of the solid electrolyte according to an aspect of the present disclosure, as an inter-electrode material in an electrochemical energy storage device.

[0333] Another aspect of the present disclosure relates to an electrode comprising a solid electrolyte according to the present disclosure and / or obtained or obtainable according to a process for producing a solid electrolyte according to the present disclosure and an electrode active material, preferably wherein the solid electrolyte forms a covering and / or coating layer on the electrode active material.

[0334] It should be noted that (preferred) embodiments and associated advantages of the process for producing a solid electrolyte according to an aspect of the present disclosure and the solid electrolyte according to another aspect of the present disclosure are also (preferred) embodiments of the electrode according to an aspect of the present disclosure and vice versa.

[0335] The electrode active material can be, for example, produced by applying a slurry containing active material particles, a binder and conductive agent particles onto a current collector. The slurry can be applied by using a coating technique known in the art, for example, drop casting, blade coating, slot die coating, spray coating, and so on. The slurry can be dried to obtain the electrode active material on top of the current collector. Subsequently, the electrode active material can be impregnated, for example, by applying a solid electrolyte precursor solution (the reaction mixture) and / or pre-crosslinked electrolyte solution onto said electrode active material. In this way, a composite electrode comprising the solid electrolyte can be obtained, with or without an overfill. The impregnation with a solid electrolyte precursor and / or precrosslinked electrolyte solution can be performed by using a coating technique known in the art, for example, drop casting, blade coating, slot die coating, spray coating and the like. The amount of solid electrolyte precursor and / or pre-crosslinked electrolyte solution can be adapted, for example, to form or not form an overfill on top of the composite electrode. The skilled person understands that the exemplary embodiment can be adapted based on the relevant assembly process strategy.

[0336] It may be, moreover, appreciated that, because of the improved properties of the herein disclosed solid electrolyte, there exists the possibility to adapt the production process, for example, to produce a selfstanding film, which was previously difficult with other types of solid electrolytes, such as pure porous silica. Nonetheless, the solid electrolyte can also be produced using classic production techniques, as described above, allowing for great adaptability based on the relevant assembly process strategy.

[0337] As described above, because the solid electrolyte of the present disclosure can demonstrate an improved ionic conductivity; therefore, an electrode comprising said solid electrolyte can demonstrate improved ionic conduction properties also. Similarly, the electrode can have improved mechanical properties due to the improved flexibility of the solid electrolyte. It is understood that any of the above embodiments of the solid electrolyte form embodiments of the electrode.

[0338] The improved structural properties can be particularly advantageous for the manufacturing of an electrode by reducing the chance of the material becoming brittle and breaking. Especially bending and rolling the electrode impregnated with the solid electrolyte and / or covered with an overfill of solid electrolyte becomes feasible. As such, the electrode size may be increased by coating on substrates of larger size and over large areas.

[0339] The term "covering" or "coating" is used to refer to a point or position where the electrode active material comes in contact with the solid electrolyte according to any of the above embodiments and results in the formation of a layer that covers and / or coats the electrode active material, more specifically on one or more surfaces thereof. Advantageously, the layer completely covers at least one surface of the electrode active material.

[0340] In some embodiments, the solid electrolyte may be a uniform covering / coating layer on the electrode active material. The term "uniform" as used herein referring to the solid electrolyte layer means that said layer does not contain segregated areas of amorphous and / or crystalline content that can be easily discerned using the analytical techniques described herein.

[0341] In some embodiments, the solid electrolyte may be a homogeneous covering / coating layer on the electrode active material. The term "homogeneous" as used herein referring to the solid electrolyte layer means that the components of said layer, are homogeneously mixed and said layer and / or a surface thereof therefore does not contain areas wherein the components can be easily discerned using the analytical techniques described herein.

[0342] In some embodiments, the solid electrolyte may be a porous covering / coating layer on the electrode active material. The term "porous" as used herein referring to the solid electrolyte layer means that said layer is intentionally designed to have a network of pores or openings that may enable the movement of ions, gases, or liquids through the material. The pores can vary in size, ranging from micropores (less than 2 nm) and mesopores (2-50 nm) to macropores (greater than 50 nm). Optionally, the porous covering / coating layer may be subjected to a calendaring step to reduce the porosity.

[0343] In some embodiments the covering layer may have dried thickness, before compression, lower than about 200 pm, preferably lower than about 150 pm; more preferably lower than about 100 pm; more preferably still lower than about 60 pm, for example 50 pm, 40 pm or 30 pm.

[0344] In some embodiments the thickness of the covering layer, preferably as excess overfill solid electrolyte, may be between 0 pm and 1000 pm, preferably between 0 pm and 300 pm, more preferably between 0 pm and 100 pm, more preferably still between 0 pm and 30 pm. The thickness of the covering layer can impact the ionic properties of the battery and the skilled person understands that the thickness of the herein described exemplary embodiments can be adapted based on the relevant assembly process strategy.

[0345] As used herein, a "thick" film refers to an electrolyte film that, after drying has a layer thickness greater than about 50 pm, and a "thin" film refers to an electrolyte film that, after drying has a layer thickness lower than about 50 pm. Advantageously, the solid electrolyte thickness, after compression, is produced to be as thin as possible while maintaining its mechanical functionality (no cracking) to separate positive and negative electrodes from each other such that the maximum Wh / L can be realised at device and stack level. Nonetheless, it should be appreciated that the herein disclosed composite electrolyte has the advantage of allowing the production of thick / thin films of varying thickness and diameter due to its improved mechanical properties as discussed earlier, making the fabrication of large and / or thick self- standing films possible, or obtaining a crack-free film of few pm (for example, in a range of >20 pm & < 150 pm on top of the electrode).

[0346] Alternatively or in combination with any of the above embodiments, the solid electrolyte may be a selfstanding film. Preferably the solid electrolyte is a homogeneous / uniform self-standing film. Due to the improved mechanical properties of the solid electrolyte, it is possible to cast a film that can be placed onto an electrode, preferably, between two opposite electrodes. The self-standing film can be produced by being deposited on a substrate that is removed after solidification of the solid electrolyte.

[0347] In some embodiments the electrode active material used in the electrode can be a positive electrode active material. Examples of the positive electrode active material may include a lithium-containing transition metal oxide, vanadium oxide, chromium oxide, and lithium-containing transition metal sulfide. Examples of the lithium-containing transition metal oxide include LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNiCoMnO2(referred as NMC family with various compositions NMXxyz, where x, y z, refers to the relative amounts of Ni, Mn and Co present in the cathode active material, for example, NMC 111 corresponding to a material composed of Ni 33.33%; Mn 33.3% and Co 3.33%; or NMC532, NMC622, NMC721, NMC811, NMC90.50.5 and any other composition of NMC or combination thereof), LiNiCoO2, LiCoMnO2, LiNiMnO2, LiNiCoMnO4, LiMnNiO4, LiMnCoO4, LiNiCoAIO2, LiNiPO4, LiCoPO4, LiMnPO4, LiFePO4, LiMnxFel-xPO4(preferably Mn content as high as possible; examples being LiMno.9Feo.iP04, LiMno.8Feo.2P04, LiMno.7Feo.3P04, LiMno.5Feo.5PO ! and the like) Li2NiSiO4, Li2CoSiO4, Li2MnSiO4, Li2FeSiO4, LiNiBO3, LiCoBO3, LiMnBO3, and LiFeBO3. Examples of the lithium-containing transition metal sulfide include LiTiS2, Li2TiS3, and Li3NbS4. One positive electrode active material or two or more positive electrode active materials selected from these positive electrode active materials can be used.

[0348] In some embodiments the electrode active material used in the electrode can be a negative electrode active material. Examples of the negative electrode active material may include a metal, semimetal, oxide, nitride, and carbon. Examples of the metal and semimetal include lithium, silicon, amorphous silicon, aluminium, silver, tin, antimony, and their alloys. Examples of the oxide can include Li4Ti50i2, Li2SrTi60i4, TiO2, Nb2O5, SnO2, Ta2O5, WO2, WO3, Fe2O3, CoO, MoO2, SiO2, SnBPO6, and their mixtures. Examples of the nitride can include LiCoN, Li3FeN2, Li7MnN4, and their mixtures. Examples of the carbon include graphite, graphene, hard carbon, carbon nanotube, and their mixtures. One negative electrode active material or two or more negative electrode active materials selected from these negative electrode active materials can be used. In some embodiments, the electrode may comprise a binder. The binder may fix particles of the electrode active material to each other. When the particles of the electrode active material are fixed to each other, occurrence of a gap due to expansion and shrinkage of the particles of the electrode active material is reduced. This reduces a decrease in the discharged capacity of a battery including the electrode. The binder may, for example, comprise carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR), and the like.

[0349] The present disclosure further encompasses a method for producing an electrode, comprising the steps of: providing an electrode active material; and forming a covering / coating layer comprising a solid electrolyte according to any of the above embodiments on the electrode active material.

[0350] In some embodiments, the electrode active material can be produced by applying a slurry containing active material particles, a binder and conductive agent particles onto a current collector, and drying said slurry to obtain the electrode active material on top of the current collector. Preferably, the slurry is applied using drop casting, blade coating, slot die coating, and / or spray coating.

[0351] In some embodiments, the electrode active material can be impregnated with the solid electrolyte by applying a solid electrolyte precursor solution and / or or pre-crosslinked electrolyte solution onto said electrode active material, and drying said impregnated electrode active material. Preferably, the impregnation is applied using drop casting, blade coating, slot die coating, and / or spray coating. Advantageously, the amount of solid electrolyte precursor and / or pre-crosslinked electrolyte solution is adapted based on the relevant assembly process strategy to form or not form an overfill on top of the composite electrode.

[0352] In certain embodiments, the electrode is a porous electrode having a plurality of pores formed by the electrode active material, preferably wherein the plurality of pores are interconnected mutually. Preferably the porous electrode has a porosity of from at least 10% to at most 60%, for example 20%, 30%, 40%, or 50%. In such embodiments, the step of forming a covering / coating layer may include impregnating the porous electrode such that the solid electrolyte fills at least a portion of the pores of the porous electrode. The solid electrolyte may at least partially fill an interior volume of the plurality of pores, or it may completely fill the interior of the plurality of pores of the porous electrode. Preferably, the step of forming a covering / coating layer may reduce the porosity of the porous electrode to a remaining porosity of less than 10%, or less than 5%, or less than 2% (after impregnation). In some embodiments, the method may comprise the step of producing a self-standing film comprising the solid electrolyte according to any of the above embodiments, and placing said self-standing film on the electrode active material. Preferably, the self-standing film can be produced by depositing a solid electrolyte precursor solution and / or or pre-crosslinked electrolyte solution on a substrate and removing said substrate after solidification of said precursor solution.

[0353] In particular embodiments, the solid electrolyte further comprises a porous substrate embedded within the cured polymer-silica network.

[0354] Another aspect of the present disclosure relates to a solid electrolyte separator, for an electrochemical energy storage device, comprising a cured polymer network and a porous substrate embedded with the cured polymer network; wherein the cured polymer network comprises polyether chains; metal ions (M+), preferably lithium ions (Li+); an ionically conductive compound; cross-links having at least two bridging moieties; wherein each bridging moiety is independently selected from the group consisting of Formula (III), Formula (IV), and Formula

[0355] (V)

[0356] It should be noted that (preferred) embodiments and associated advantages of the process for producing a solid electrolyte according to an aspect of the present disclosure, the solid electrolyte according to another aspect of the present disclosure and the electrode according to another aspect of the present disclosure are also (preferred) embodiments of the solid electrolyte separator according to an aspect of the present disclosure and vice versa. The solid electrolyte separator as disclosed herein is suitable for use in an electrochemical energy storage device, such as an electrochemical cell or a battery, that may be configured to physically separate a positive electrode (i.e., cathode) and negative electrode (i.e., anode), while allowing the passage of ions for charging and discharging of the storage device. The "electrolyte" comprised in the solid electrolyte separator provides a medium that allows the movement of said ions, but is electrically insulating and therefore does not conduct electrons. This ensures that the electrical energy of an energy storage device is stored and released through an external circuit.

[0357] In contrast to conventional separators requiring a highly porous structure with a large plurality of pores to facilitate the transport of the ions from one electrode to another electrode through a liquid medium, the present solid electrolyte separator provides that the movement of ions is facilitated and / or stimulated by the solid electrolyte embedded and formed 'in-situ' within the pores of the porous substrate. Moreover, it has been found that by embedding the solid electrolyte in the pores of the substrate, the present solid electrolyte separator can provide a stronger physical barrier with improved protection against short circuiting, even at reduced thickness.

[0358] In particular embodiments, the solid electrolyte separator may further comprise a layer of the cured polymer network positioned on at least one side of the porous substrate, preferably at least two layers of the cured polymer network positioned on at least two opposite sides of the porous substrate, wherein the layer is configured for ionically connecting to an active electrode material. Advantageously, the layer may fill in any voids or surface inconsistencies on the porous substrate, resulting in a more homogenous and uniform surface of the solid electrolyte separator.

[0359] Hence, the solid electrolyte may simultaneously provide reinforcement to the substrate (i.e., through the embedded material) and adherence to other components (i.e., through the one or more layers), such as components of an electrochemical energy storage device. Preferably, the layer may comprise the same solid electrolyte material as embedded within porous substrate.

[0360] In particular embodiments, the solid electrolyte layer can be obtained by adding an excess amount of solid electrolyte material to the porous substrate, sufficient for overfilling of the pores of the porous substrate with the solid electrolyte material, thereby forming an overfill layer on a side of the porous substrate. The thickness of the layer can be controlled by managing the excess amount of solid electrolyte material added to the porous substrate. Alternatively or in combination, the thickness of the layer can be reduced after solidification. For example, chemical etching can be used to remove a portion of the layer, or the layer's surface can be mechanically removed through grinding or cutting. In particular embodiments, the cured polymer network layer has an average thickness of between 0.01 pm and 50.0 pm, or between 0.01 pm and 45.0 pm, or between 0.01 pm and 40.0 pm, or between 0.01 pm and 35.0 pm, or between 0.01 pm and 30.0 pm, or between 0.5 pm and 30.0 pm, or between 1.0 pm and 30.0 pm.

[0361] The porous substrate may refer to a membrane, a nonwoven fabric, a woven fabric, a continuous sheet, or a film that has desirable thermomechanical properties. Any organic material or inorganic material having sufficient electrical insulation properties (i.e., to block the transfer of electrons between the anode and cathode) and electrochemical stability can be used as a material to form the porous substrate.

[0362] In particular embodiments, the porous substrate may comprise a polymer material and / or a fibrous material. Non-limiting examples of a fibrous material include glass fibers and / or carbon fibers.

[0363] In particular embodiments, the porous substrate comprises a polymer selected from the group consisting of polypropylene, polyethylene, polystyrene, polyacrylonitrile, Nylon 6, Nylon 6,6, polyether sulfone, polyether ether ketone, cellulose acetate, cellulose triacetate, cellulose, polyimide, polyvinylidene fluoride, and mixtures thereof; preferably wherein the porous substrate comprises a plurality of polymer layers, preferably at least three polymer layers.

[0364] Alternatively, or in combination, the porous substrate comprises aluminum oxide.

[0365] In particular embodiments, the porous substrate may comprise a multilayer polymer. Preferably, the porous substrate comprises a plurality of polymer layers, preferably at least three polymer layers, for example a trilayer polymer, or more layers, such as four polymer layers, five polymer layers, or more. Advantageously, the substrate may be a multilayer polymer. The advantage of having three or more layers is that the one or more inner layers may provide for a thermal shutdown function to avoid thermal runaway of the electrochemical cell or battery.

[0366] Another aspect of the present disclosure relates to an electrode assembly comprising an electrode according to an aspect of the present disclosure, and preferably one or more separators, more preferably one or more solid electrolyte separators according to an aspect of the present disclosure.

[0367] It should be noted that (preferred) embodiments and associated advantages of the process for producing a solid electrolyte according to an aspect of the present disclosure, the solid electrolyte according to another aspect of the present disclosure, the electrode according to another aspect of the present disclosure, and the solid electrolyte separator according to another aspect of the present disclosure are also (preferred) embodiments of the electrode assembly according to an aspect of the present disclosure and vice versa. Another aspect of the present disclosure relates to an electrochemical energy storage device, such as a battery or cell, comprising a positive electrode, a negative electrode, and a solid electrolyte according to an aspect of the present disclosure and / or obtained or obtainable according to a process for producing a solid electrolyte according to the present disclosure. It is understood that an electrochemical energy storage device may comprise various combinations of electrode, for example, a plurality of negative and positive electrodes that are advantageously stacked on top of each other. Techniques for producing a power storage device from a solid electrolyte are known in the art.

[0368] It should be noted that (preferred) embodiments and associated advantages of the process for producing a solid electrolyte according to an aspect of the present disclosure, the solid electrolyte according to another aspect of the present disclosure, the electrode according to another aspect of the present disclosure, the solid electrolyte separator according to another aspect of the present disclosure, and the electrode assembly according to another aspect of the present disclosure are also (preferred) embodiments of the electrochemical energy storage device according to an aspect of the present disclosure and vice versa.

[0369] As used herein, an "electrochemical energy storage device" refers to a device capable of either generating electrical energy from chemical reactions or using electrical energy to cause chemical reactions. The technology of the present disclosure can be regarded as general-purpose technology in the sense that it can be readily adapted for a variety of different electrochemical energy storage device, including for example, solid-state electrochemistry which may be implemented in various battery applications, such as automotive, aviation, marine, space, but not limited thereto.

[0370] In some embodiments, the electrochemical energy storage device may comprise the solid electrolyte as a self-standing film that is arranged on at least one electrode, preferably, between two opposite electrodes. As described above, because the solid electrolyte of the present disclosure can demonstrate improved ionic conductivity; therefore, a power storage device comprising an electrode with said solid electrolyte can demonstrate improved ionic conduction properties also. Similarly, the power storage device can have improved mechanical properties due to the improved flexibility of the solid electrolyte comprised in the electrode. It is understood that any of the above embodiments of the solid electrolyte form embodiments of the power storage device.

[0371] In particular embodiments, the electrochemical energy storage device may further comprise one or more separators, preferably one or more solid electrolyte separators according to an aspect of the present disclosure. When describing the present disclosure, the terms used are to be construed in accordance with the following definitions, unless a context dictates otherwise.

[0372] As used herein, the singular forms "a", "an", and "the" include both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a step" means one step or more than one step. The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, nonrecited members, elements, or method steps. The terms also encompass "consisting of" and "consisting essentially of", which enjoy well-established meanings in patent terminology.

[0373] Whereas the terms "one or more" or "at least one", such as one or more members or at least one member of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any >3, >4, >5, >6 or >7 etc. of said members, and up to all said members. In another example, "one or more" or "at least one" may refer to 1, 2, 3, 4, 5, 6, 7 or more.

[0374] The terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order, unless specified. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the disclosure described herein are capable of operation in other sequences than described or illustrated herein.

[0375] As used herein, the term "and / or" when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a list is described as comprising group A, B, and / or C, the list can comprise A alone, B alone, C alone, A and B in combination, A and C in combination, B and C in combination, or A, B, and C in combination.

[0376] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" or "in a particular embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while certain embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the disclosure, and form different embodiments, as would be understood by those in the art.

[0377] The recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g. 1 to 5 can include 1, 2, 3, 4 when referring to, for example, a number of elements, and can also include 1.5, 2, 2.75 and 3.80, when referring to, for example, measurements). The recitation of endpoints also includes the end point values themselves (e.g. from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all sub-ranges subsumed therein. This applies to numerical ranges irrespective of whether they are introduced by the expression "from... to..." or the expression "between... and..." or another expression.

[0378] As used herein, the terms "about" or "approximately" are used to provide flexibility to a numerical value or range endpoint by providing that a given value may be "a little above" or "a little below" said value or endpoint, depending on the specific context. Hence, the terms "about" or "approximately" as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, are meant to encompass variations of and from the specified value or endpoint, such as variations of + / - 10% or less, preferably + / -5% or less, more preferably + / -!% or less, and still more preferably + / -0.1% or less of and from the specified value, insofar such variations are appropriate to perform in the present disclosure.

[0379] Unless otherwise stated, use of the terms "about" or "approximately" in accordance with a specific number or numerical range should also be understood to provide support for such numerical terms or range without the term "about". For example, the recitation of "about 30" should be construed as not only providing support for values a little above and a little below 30, but also for the actual numerical value of 30 as well.

[0380] As used herein, the term "substantially" refers to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result. For example, an object that is "substantially" enclosed would mean that the object is either completely enclosed or nearly completely enclosed. The exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context. However, generally speaking the nearness of completion will be so as to have the same overall result as if absolute and total completion were obtained. The use of "substantially" is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result. The terms "vol%", or "mol%" refers to a weight percentage of a component, a volume percentage of a component, or molar percentage of a component, respectively, based on the total weight, the total volume of material, or total moles, which includes the component.

[0381] Reference in this specification may be made to devices, structures, systems, or methods that provide "improved" performance (e.g. increased or decreased results, depending on the context). It is to be understood that unless otherwise stated, such "improvement" is a measure of a benefit obtained based on a comparison to devices, structures, systems or methods in the prior art. Furthermore, it is to be understood that the degree of improved performance may vary between disclosed embodiments and that no equality or consistency in the amount, degree, or realization of improved performance is to be assumed as universally applicable.

[0382] Reference in this specification may be made to devices, structures, systems, or methods that provide "improved" performance (e.g. increased or decreased results, depending on the context). It is to be understood that unless otherwise stated, such "improvement" is a measure of a benefit obtained based on a comparison to devices, structures, systems or methods in the prior art. Furthermore, it is to be understood that the degree of improved performance may vary between disclosed embodiments and that no equality or consistency in the amount, degree, or realization of improved performance is to be assumed as universally applicable.

[0383] EXAMPLES

[0384] Examples of an implementation of the technology according to the present disclosure is given hereinbelow. The provision of examples is meant to aid the reader in understanding the technological concepts more easily, but it is not meant to identify the most important or essential features thereof, nor is it meant to limit the scope of the present disclosure.

[0385] Throughout the examples, the following abbreviations are used: l,3,5-tris[3-(trimethoxysilyl)propyl]- l,3,5-triazine-2,4,6(lH,3H,5H)-trione (VPS); halloysite nanotubes (HNT), silane terminated polyethylene glycol (SPEG); tetraethoxysilane (TEOS); l-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIFSI); Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI); lithium nickel manganese cobalt oxides (NMC) cathode; lithium ferro-phosphate (LFP); thermal gravimetric analysis (TGA); scanning electron microscope (SEM); electrochemical impedance spectroscopy (EIS); Linear sweep voltammetry (LSV); Electrochemical stability window (ESW). Comparative Example 1: Solid electrolyte without cross-linker

[0386] As a comparative example, a solid electrolyte was prepared in the form of a self-standing film by curing a curable composition in the absence of a cross-linker.

[0387] First, a curable composition was prepared under continuous stirring comprising

[0388] 5.7 wt.% of Trimethoxysilylpropoxypolyethyleneoxide, Methyl Ether (monofunctional SPEG) (having a molecular weight of 600 g / mol);

[0389] 1.2 wt.% of halloysite nanotubes (HNT);

[0390] 8.3 wt.% of a 1.5 mol / L LiTFSI solution;

[0391] - 26.6 wt.% of EMIFSI;

[0392] - 14.7 wt.% of TEOS

[0393] 43.5 wt.% of solvent comprising 15.7:27.8 of water: l-methoxy-2-propanol; with wt.% relative to the total weight of the curable composition.

[0394] The curable composition was subsequently drop-cast in a stainless steel CR2025 coin cell cap used as a mold. Around 0.2 g of the sol was used per mold. The drop cast sol was kept at ambient temperature (40- 60% relative humidity and 20.5-22.5°C) for 12 hours to cure the curable composition and obtain a wet solid electrolyte.

[0395] Subsequently, the wet samples were demolded and dried at 60 °C under vacuum (< 10'2mbar) for 3 days to obtain a dry solid electrolyte in the form of pellets (until a water content of less than 600 ppm). The self-standing solid electrolyte pellets of 220-230 pm thickness were kept in a dry room atmosphere prior to use. The resulting comparative solid electrolyte (CE1) comprised 10.0 wt.% of SPEG and 2.0 wt.% of halloysite nanotubes; with wt.% relative to the total weight of the solid electrolyte.

[0396] Example 1: Solid electrolyte with cross-linker

[0397] In a first example, a number of solid electrolytes according to the present disclosure were prepared in the form of self-standing films by curing a curable composition.

[0398] First, a curable composition was prepared under continuous stirring comprising:

[0399] 5.7 wt.% of Trimethoxysilylpropoxypolyethyleneoxide, Methyl Ether (SPEG) (having a molecular weight of 600 g / mol);

[0400] 0.6 wt.% of l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lH,3H,5H)-trione (VPS);

[0401] 1.2 wt.% of halloysite nanotubes (HNT);

[0402] 8.2 wt.% of a 1.5 mol / L LiTFSI solution; 26.5 wt.% of EMIFSI;

[0403] 14.6 wt.% of TEOS

[0404] 43.2 wt.% of solvent comprising 15.6:27.6 of water:l-methoxy-2-propanol; with wt.% relative to the total weight of the curable composition.

[0405] The curable composition was subsequently drop-cast in a stainless steel CR2025 coin cell cap used as a mold. Around 0.2 g of the sol was used per mold. The drop cast sol was kept at ambient temperature (40- 60% relative humidity and 20.5-22.5°C) for 12 hours to cure the curable composition and obtain a wet solid electrolyte.

[0406] Subsequently, the wet samples were demolded and dried at 60 °C under vacuum (< 10'2mbar) for 3 days to obtain a dry solid electrolyte in the form of pellets (until a water content of less than 600 ppm). The self-standing solid electrolyte pellets of 220-230 pm thickness were kept in a dry room atmosphere prior to use. The resulting solid electrolyte (SEI) comprised 10.0 wt.% of SPEG, 2.0 wt.% of halloysite nanotubes, and 1.0 wt.% of VPS; with wt.% relative to the total weight of the solid electrolyte.

[0407] The same procedure was repeated, but with a curable composition comprising:

[0408] 5.7 wt.% of Trimethoxysilylpropoxypolyethyleneoxide, Methyl Ether (SPEG) (having a molecular weight of 600 g / mol);

[0409] 1.2 wt.% of l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lH,3H,5H)-trione (VPS);

[0410] 1.2 wt.% of halloysite nanotubes (HNT);

[0411] 8.2 wt.% of a 1.5 mol / L LiTFSI solution;

[0412] - 26.3 wt.% of EMIFSI;

[0413] - 14.5 wt.% of TEOS

[0414] 42.9 wt.% of solvent comprising 15.5:27.8 of water: l-methoxy-2-propanol; with wt.% relative to the total weight of the curable composition.

[0415] The resulting solid electrolyte (SE2) comprised 10.0 wt.% of SPEG, 2.0 wt.% of halloysite nanotubes, and 2.0 wt.% of VPS; with wt.% relative to the total weight of the solid electrolyte.

[0416] The same procedure was repeated, but with a curable composition comprising:

[0417] 5.8 wt.% of Trimethoxysilylpropoxypolyethyleneoxide, Methyl Ether (SPEG) (having a molecular weight of 600 g / mol);

[0418] 1.7 wt.% of l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lH,3H,5H)-trione (VPS);

[0419] 1.2 wt.% of halloysite nanotubes (HNT);

[0420] 8.1 wt.% of a 1.5 mol / L LiTFSI solution; 26.1 wt.% of EMIFSI;

[0421] 14.4 wt.% of TEOS

[0422] 42.7 wt.% of solvent comprising 15.4:27.3 of water:l-methoxy-2-propanol; with wt.% relative to the total weight of the curable composition.

[0423] The resulting solid electrolyte (SE3) comprised 10.0 wt.% of SPEG, 2.0 wt.% of halloysite nanotubes, and 3.0 wt.% of VPS; with wt.% relative to the total weight of the solid electrolyte.

[0424] The same procedure was repeated, but a curable composition comprising:

[0425] 5.8 wt.% of Trimethoxysilylpropoxypolyethyleneoxide, Methyl Ether (SPEG) (having a molecular weight of 600 g / mol);

[0426] 2.3 wt.% of l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lH,3H,5H)-trione (VPS);

[0427] 1.2 wt.% of halloysite nanotubes (HNT);

[0428] 8.0 wt.% of a 1.5 mol / L LiTFSI solution;

[0429] - 26.0 wt.% of EMIFSI;

[0430] - 14.3 wt.% of TEOS

[0431] 42.3 wt.% of solvent comprising 15.3:27 of water:l-methoxy-2-propanol; with wt.% relative to the total weight of the curable composition.

[0432] The resulting solid electrolyte (SE4) comprised 10.0 wt.% of SPEG, 2.0 wt.% of halloysite nanotubes, and 4.0 wt.% of VPS; with wt.% relative to the total weight of the solid electrolyte.

[0433] The same procedure was repeated, but a curable composition comprising:

[0434] 5.8 wt.% of Trimethoxysilylpropoxypolyethyleneoxide, Methyl Ether (SPEG) (having a molecular weight of 600 g / mol);

[0435] 2.9 wt.% of l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lH,3H,5H)-trione (VPS);

[0436] 1.2 wt.% of halloysite nanotubes (HNT);

[0437] 8.0 wt.% of a 1.5 mol / L LiTFSI solution;

[0438] - 25.9 wt.% of EMIFSI;

[0439] - 14.2 wt.% of TEOS

[0440] 42 wt.% of solvent comprising 15.2:26.8 of water:l-methoxy-2-propanol; with wt.% relative to the total weight of the curable composition.

[0441] The resulting solid electrolyte (SE5) comprised 10.0 wt.% of SPEG, 2.0 wt.% of halloysite nanotubes, and 5.0 wt.% of VPS; with wt.% relative to the total weight of the solid electrolyte. Example 2: Characteristics of the produced solid electrolytes

[0442] In a second example, the ionic conductivity as well as the mechanical properties of the solid electrolytes of Example 1 were compared to the solid electrolyte of Comparative Example 1. As shown in Table 1 below, curable compositions comprising a higher amount of VPS cross-linker provided solid electrolytes with improved conductivity. Moreover, the solid electrolytes of Example 1, according to the present disclosure, are characterized by an improved mechanical strength (G') as determined from the damping factor (i.e., the ratio of the loss modulus G" and storage modulus G').

[0443] Table 1

[0444] Ionic conductivity performance

[0445] The ionic conductivity of the solid electrolyte films was characterised at room temperature (20 °C) using EIS without any external pressure applied to the film. Each electrolyte film was sandwiched between a stainless-steel (SS) disk (d = 1.5 cm) to form a symmetric [SS / electrolyte / SS] cell. Next, an alternating potential was applied to the electrolytic cell with an amplitude of 10 mV within a frequency range of 1 Hz to 50,000 Hz. The resulting alternating current flowing through the cell is measured and converted to conductivity values. A suitable device for EIS measurements includes a VMP-3 BioLogic instrument.

[0446] The electrochemical properties of solid electrolytes SEI-5 from Example 1 and the solid electrolyte CE1 of Comparative Example 1 are depicted in FIG.l. Based on the results in FIG.l, an uprising trend in ionic conductivity is observed when increasing the amount of VPS cross-linker in the cured polymer network. Mechanical properties

[0447] Viscoelastic properties of the aforementioned solid electrolytes were compared to assess the impact on mechanical stability. To measure the viscoelastic properties of each solid electrolyte pellets of 15 mm diameter were used. The damping factor (tan 6), as calculated from the ratio of the loss modulus G" and the storage modulus G', was measured using oscillatory frequency sweep measurements on a rotational rheometer operating in oscillatory mode with a constant shear strain of 1% and a variable frequency of from 0.01 Hz to 100 Hz at 20 °C. The constant shear strain of 1% was determined to be in the linear viscoelastic (LVE) range of each pellet sample.

[0448] As shown in Table 1 and FIGs. 2-3, addition of VPS cross-linker leads to a lower damping factor due to an increase in storage modulus G' and higher mechanical strength, resulting in a more elastic behaviour which is required to resist commonly observed dendrite growth of the metal anode.

[0449] Example 3: Characteristics of selected solid electrolytes

[0450] In a third example, electrochemical properties and thermal properties were further investigated by comparing solid electrolyte SE4 of Example 1 to solid electrolyte CE1 of Comparative Example 1. As shown in Table 2 below, and FIGs. 4-5, addition of VPS cross-linker enhances the electrochemical stability window (ESW) and anodic current limit of the solid electrolyte. Hence, the solid electrolyte as described herein may provide a more stable working voltage during charge-discharge cycling and provide a higher anodic current limit when compared to what is disclosed in the state of the art.

[0451] Moreover, as shown in FIG. 6, the addition of VPS cross-linker also increased the thermal stability of the solid electrolyte as determined by dynamic thermogravimetric analysis (TGA).

[0452] Table 2

[0453] Electrochemical stability window (ESW) and anodic current limit

[0454] Linear sweep voltammetry (LSV) was used to determine the electrochemical stability window (ESW) of solid electrolytes SE4 and CE1, preferably as an electrolytic cell comprising said solid electrolyte. A typical linear sweep voltammetry (LSV) experiment was conducted on an electrolytic SUS | | Li cell assembled with the corresponding solid electrolyte film in a crimped coin cell with a scan rate of 20 mV / s.

[0455] To measure the anodic current limit, each respective solid electrolyte was sandwiched between Li electrodes to form electrolytic cell 2. Next, voltammetry experiments were conducted by measuring the current as a function of potential using chronoamperometry at 1 V. The maximum current observed is the anodic current limit.

[0456] Thermal stability

[0457] To measure the thermal stability, each respective solid electrolyte was prepared into pellets of 20 mm of diameter. Subsequently, a sample was taken and subjected to dynamic TGA conducted under nitrogen at a heating rate of 10 “C.min1from 25 °C to 800 °C. The thermal stability can be determined from the temperature at 3% weight loss or 5% weight loss, respectively.

[0458] Example 4: Charge and discharge efficiency of selected solid electrolytes

[0459] In a fourth example, the charge and discharge efficiency of solid electrolytes SE4 and CE1 was compared when used for the impregnation of a cathode.

[0460] To that end, a composite cathode (a lithium ferro-phosphate (LFP) cathode) comprising an active material loading of ImAh / cm2was impregnated by providing a curable composition according to the procedure of Example 1 with the difference that the sol was drop-cast in the cathode instead of a coin cell, resulting in cathode 1.

[0461] The aforementioned procedure of drop-casting the precursor solution in the cathode was repeated with the difference that the curable composition of Comparative Example 1 was used, resulting in comparative cathode 1.

[0462] Next, the performance characteristics of the impregnated cathodes 1 and comparative cathode 1, voltage changes during discharge were measured after 55 cycles. As shown in Table 3 below, and FIGs. 7-10 the discharge capacity and coulombic efficiency significantly improved by addition of cross-linker as defined herein.

[0463] Table 3

[0464] Example 5: Electrochemical energy storage device comprising a single unit cell

[0465] Example 5 illustrates single unit cells comprising a solid electrolyte separator as disclosed herein, which comprises a commercially available porous substrate CES (Cambridge Energy Solutions substrate: 12 pm Microporous Monolayer Membrane of polyethylenecoated with 2pm of AIOXon each side) embedded with a solid electrolyte as disclosed herein.

[0466] Impregnation of the porous substrate to form a solid electrolyte separator

[0467] The porous substrate CES was blade coated with a curable composition comprising

[0468] 5.8 wt.% of Trimethoxysilylpropoxypolyethyleneoxide, Methyl Ether (SPEG) (having a molecular weight of 600 g / mol); 2.3 wt.% of l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lH,3H,5H)-trione (VPS);

[0469] 1.2 wt.% of halloysite nanotubes (HNT);

[0470] 8.0 wt.% of a 1.5 mol / L LiTFSI solution;

[0471] 26.0 wt.% of tetraethylene glycol dimethyl ether (TEGDM) ;

[0472] - 14.3 wt.% of TEOS;

[0473] 42.3 wt.% of solvent comprising 15.3:27 of water:l-methoxy-2-propanol; with wt.% relative to the total weight of the curable composition.

[0474] Prior to coating the porous CES substrate, the curable composition was heated at 60 °C for 30 to 35 hours in a convection oven to initiate gelation and increase the viscosity of the curable composition. After obtaining a desirable viscosity, the curable composition was applied to the porous substrate via a blade coating technique. In particular, blade coating of electrolyte solution into CES spacer in both side, which used as mechanical separator to have very thin film (35 pm). The impregnated substrate was subsequently subjected to an ageing step at room temperature for 12 hours in a fume hood. The obtained solid electrolyte separator 1 was subsequently dried at 60 °C for 15h under vacuum of 6 mbar (until a water content of less than 600 ppm). The dried solid electrolyte separator 1 was characterized by a thickness of 35 pm, and two solid electrolyte layers that each have a thickness of about 10 pm and are positioned on opposite sides of the substrate.

[0475] Formation of the electrochemical energy storage device

[0476] Two different electrochemical energy storage devices comprising one unit cell were assembled under dry room conditions at about 22 °C with a dew point below -45.

[0477] Firstly, a stack was prepared by pressing a composite cathode (a lithium nickel manganese cobalt oxides (NMC) cathode) comprising an active material loading of 2mAh / cm2on a single-layer cathode footprint measuring 3 x 4.5 cm2(or 13.5 cm2) onto the formed solid electrolyte separator 1 by applying a pressure of 1250 kPa. Then, a lithium metal electrode with a thickness of 26 pm was pressed onto the opposite side of the solid electrolyte separator 1 by applying a pressure of 1250 kPa to form the unit cell. A Ni / Cu tab was welded to the copper current collector, while an Al tab was welded to the aluminum current collector using an ultrasonic welding device. The resulting stack was positioned between two pouch foils, each measuring 8 x 5 cm2, and the pouch foil was sealed using a vacuum sealing device to obtain cell 1.

[0478] Secondly, a stack was prepared by pressing a composite cathode (a lithium ferro-phosphate (LFP) cathode) comprising an active material loading of ImAh / cm2on a single-layer cathode footprint measuring 3 x 4.5 cm2(or 13.5 cm2) onto the formed solid electrolyte separator 1 by applying a pressure of 1250 kPa. Then, a lithium metal electrode with a thickness of 26 pm was pressed onto the opposite side of the solid electrolyte separator 1 by applying a pressure of 1250 kPa to form the unit cell. A Ni / Cu tab was welded to the copper current collector, while an Al tab was welded to the aluminum current collector using an ultrasonic welding device. The resulting stack was positioned between two pouch foils, each measuring 8 x 5 cm2, and the pouch foil was sealed using a vacuum sealing device to obtain cell 2.

[0479] Electrochemical performances

[0480] The electrochemical characterization of the obtained energy storage devices pouch cell 1 and cell 2 was conducted in a Cell Test System at a controlled temperature of 45.0 ± 0.5QC. Testing was performed at different C-rates, including C / 20 for the formation cycle tests. Additionally, the cycle life of the pouch cells was evaluated through continuous charge-discharge cycles within a voltage window of 3.0-4.2 V.

[0481] As shown in FIG. 11, the discharge capacity of cell 1 remained around 135 mAh / g for up to 50 cycles at 1250 kPa and a C / 3 discharge rate. FIG. 12 further illustrates the effect of different C-rates on the discharge capacity of cell 1.

[0482] As shown in FIG. 13, the discharge capacity of cell 2 remained around 150 mAh / g for up to 25 cycles at 1250kPa and a C / 3 discharge rate. FIG. 14 further illustrates the effect of different C-rates on the discharge capacity of cell 2.

[0483] From the data presented in FIG. 11-14 it follows that the obtained energy storage devices according to the present disclosure are advantageously characterized by a high discharge specific capacity and about 100% Coulombic efficiency.

[0484] Comparative Example 2: Solid electrolyte with cross-linker

[0485] As another comparative example, a solid electrolyte was prepared in the form of a self-standing film by curing a curable composition in the absence of clay mineral particles, more specifically without halloysite nanotubes (HNT).

[0486] Specifically, a curable composition (Comparative Example 2) was prepared under continuous stirring comprising:

[0487] 5.7 wt.% of Trimethoxysilylpropoxypolyethyleneoxide, Methyl Ether (SPEG) (having a molecular weight of 600 g / mol);

[0488] 0.8 wt.% of l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lH,3H,5H)-trione (VPS);

[0489] 8.2 wt.% of a 1.5 mol / L LiTFSI solution;

[0490] - 26.5 wt.% of EMIFSI; 14.6 wt.% of TEOS

[0491] 44.2 wt.% of solvent comprising water and l-methoxy-2-propanol in a 15.6:27.6 ratio; with wt.% relative to the total weight of the curable composition.

[0492] Example 6: Solid electrolyte with cross-linker and clay mineral particles

[0493] A curable composition was prepared under continuous stirring comprising:

[0494] 5.7 wt.% of Trimethoxysilylpropoxypolyethyleneoxide, Methyl Ether (SPEG) (having a molecular weight of 600 g / mol);

[0495] 0.8 wt.% of l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lH,3H,5H)-trione (VPS);

[0496] 1.0 wt.% of halloysite nanotubes (HNT);

[0497] 8.2 wt.% of a 1.5 mol / L LiTFSI solution;

[0498] - 26.5 wt.% of EMIFSI;

[0499] - 14.6 wt.% of TEOS

[0500] 43.2 wt.% of solvent comprising water and l-methoxy-2-propanol in a 15.6:27.6 ratio; with wt.% relative to the total weight of the curable composition.

[0501] The curable composition was subsequently drop-cast in a stainless steel CR2025 coin cell cap used as a mold. Around 0.2 g of the sol was used per mold. The drop cast sol was kept at ambient temperature (40- 60% relative humidity and 20.5-22.5°C) for 12 hours to cure the curable composition and obtain a wet solid electrolyte.

[0502] Subsequently, the wet samples were demolded and dried at 60 °C under vacuum (< 10'2mbar) for 3 days to obtain a dry solid electrolyte in the form of pellets (until a water content of less than 600 ppm). The self-standing solid electrolyte pellets of 220-230 pm thickness were kept in a dry room atmosphere prior to use.

[0503] The resulting solid electrolyte (SE6) comprised 10.0 wt.% of SPEG, 1.8 wt.% of halloysite nanotubes, and 1.4 wt.% of VPS; with wt.% relative to the total weight of the solid electrolyte.

[0504] Example 7: Characteristics of the produced solid electrolytes

[0505] The ionic conductivity as well as the thermal properties of the solid electrolytes of Example 6 (SE6) were compared to the solid electrolyte of Comparative Example 2 (CE2). As shown in Table 4 below, curable compositions comprising a higher amount of HNT provided solid electrolytes with improved conductivity. Moreover, the solid electrolytes of Example 6, according to the present disclosure, also exhibited an improved thermal stability, as further shown in Table 5.

[0506] Table 4

[0507] Ionic conductivity performance

[0508] The ionic conductivity of the solid electrolyte films was characterised at various temperatures (ranging from 25-100 °C) using EIS without applying any external pressure to the film. Each electrolyte film was sandwiched between a stainless-steel (SS) disk (diameter = 1.5 cm) to form a symmetric [SS / electrolyte / SS] cell. Next, an alternating potential was applied to the electrolytic cell with an amplitude of 10 mV within a frequency range of 1 Hz to 50,000 Hz. The resulting alternating current flowing through the cell is measured and converted to ionic conductivity values. A suitable device for EIS measurements includes a

[0509] VMP-3 BioLogic instrument.

[0510] The electrochemical properties of solid electrolytes SE1-SE5 (Example 1) and the solid electrolyte CE1

[0511] (Comparative Example 1) are depicted in FIG.15. As shown in FIG.15, an upward trend in ionic conductivity is observed when increasing the amount of HNT in the cured polymer network.

[0512] Thermal stability

[0513] To measure the thermal stability, each respective solid electrolyte was prepared into pellets of 20 mm of diameter. Subsequently, a sample was taken and subjected to dynamic TGA conducted under nitrogen at a heating rate of 10 “C.min1from 25 °C to 600 °C. The thermal stability can be determined from the temperature at 5% weight loss (T5%) and the residual mass at 600 °C. As shown in FIG. 16, the solid electrolyte SE6 exhibits improved thermal stability compared to CE2.

[0514] Table 5 >

Claims

CLAIMS1. A process for producing a solid electrolyte, the process comprising the steps of: providing a curable composition comprising• a polyether compound comprising at least one polyalkoxy silyl functional group;• a cross-linker comprising at least two polyalkoxy silyl functional groups and a metal ion (M+) chelating moiety;• a metal (M+) salt, preferably a lithium (Li+) salt;• clay mineral particles;• optionally, an ionically conductive compound; and• a solvent comprising water, and preferably one or more alcohols; curing the curable composition, thereby obtaining the solid electrolyte; and, optionally, drying the solid electrolyte.

2. The process according to claim 1, wherein the polyalkoxy silyl functional group is a hydrolysable group selected from the group consisting of: trialkoxy silyl (-SifOR^OR^OR3)), dialkoxy alkyl silyl (-Si(OR4)(OR5)(R6)), monoalkoxy dialkyl silyl (-Si(OR7)(R8)(R9)), and / or combinations thereof.

3. The process according to any one of the preceding claims, wherein the polyether compound comprises repeating units of Formula (I) and / or (II)wherein n is a positive integer, preferably n ranging from 3-15 000; and wherein m is a positive integer, preferably m ranging from 3-15 000.

4. The process according to any one of the preceding claims, wherein the metal ion (M+) chelating moiety is a cyclic moiety or a macrocyclic moiety.

5. The process according to any one of the preceding claims, wherein the curable composition comprises at least 0.5 wt.% of the cross-linker; with wt.% relative to the total weight of the curable composition.

6. The process according to any one of the preceding claims, wherein the cross-linker comprises at least three polyalkoxy silyl functional groups.

7. The process according to claim 6, wherein the cross-linker is selected from the group consisting of: l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lh,3h,5h)-trione, tris(3-(trimethoxysilyl)propyl)amine, l,l,l,3-tris(3-(triethoxysilyl) propyl) urea, and mixtures thereof.

8. The process according to any one of the preceding claims, wherein the clay mineral particles are selected from the group consisting of: palygorskite, attapulgite, kaolin, smectite, illite, chlorite, sepiolite, vermiculite, and / or mixtures thereof; preferably selected from palygorskite, kaolin and / or attapulgite; more preferably wherein the clay mineral particles comprise halloysite nanotubes (HNT) comprising aluminosilicate (Al2Si2Os(OH)4).

9. The process according to any one of the preceding claims, wherein the curable composition further comprises a compound selected from the group consisting of: tetraalkoxy silane, trialkoxy alkyl silane, dialkoxy dialkyl silane, alkoxy trialkyl silane, and / or mixtures thereof.

10. The process according to any one of the preceding claims, wherein the metal salt is a lithium (Li+) salt selected from the list consisting of: Lithium bis(trifluoromethanesulfonyl)imide (LiFSI), Lithium bis(trifluoromethane)sulfonimide (LiTFSI), Lithium hexafluorophosphate (LiPF6), Lithium tetrafluoroborate (LiBF4), Lithium bis(oxalato)borate (LiBOB), Lithium difluoro(oxalate)borate (LiODFB), Lithium nitrate (LiNO3), Lithium perchlorate (LiCIO4), and / or combinations thereof.

11. The process according to any one of the preceding claims, wherein the curable composition further comprises l-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIFSI), or tetraethylene glycol dimethyl ether (TEGDM), and / or N-methylacetamide.

12. A solid electrolyte, for an electrochemical energy storage device, comprising a cured polymer network; wherein the cured polymer network comprises: a polymeric matrix comprising polyether chains; metal ions (M+), preferably lithium ions (Li+); metal ion (M+) chelating moieties; clay mineral particles; optionally, an ionically conductive compound; and,cross-links comprising siloxane (-Si-O-Si-) bonds.

13. The solid electrolyte according to claim 12, wherein the metal ion chelating moiety is a cyclic moiety or a macrocyclic moiety.

14. The solid electrolyte according to any one of claims 12 or 13, further comprising a porous substrate embedded within the cured polymer network.

15. An electrode comprising an electrode active material and a solid electrolyte according to any one of claims 12 to 14.

16. The electrode according to claim 15, wherein the solid electrolyte forms a covering and / or coating layer on the electrode active material, and / or wherein the electrode has a plurality of pores formed by the electrode active material and the solid electrolyte fills at least a portion of the electrode's pores.

17. An electrode assembly comprising an electrode according to claim 15 or 16, further comprising one or more separators in the form of a solid electrolyte according to any one of claims 12 to 14.

18. The electrode assembly according to claim 17, wherein the water content in the electrode and / or the separator is at most 1500 ppm, preferably at most 1000 ppm, more preferably at most 500 ppm or less, for example 100 ppm or 50 ppm, preferably after drying.

19. An electrochemical energy storage device, comprising a positive electrode, a negative electrode, and a solid electrolyte according to any one of claims 12 to 14.

20. The electrochemical energy storage device according to claim 19, further comprising one or more separators in the form of a solid electrolyte according to any one of claims 12 to 14.

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