Crosslinked 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, a solid-state battery, and a method for producing the same. An aspect of the present disclosure relates to a process for producing a solid electrolyte, comprising the steps of: - contacting, in the presence of a catalyst: - a polymer precursor compound comprising polyethylene glycol (PEG) and / or polytetrahydrofuran (PTHF), wherein the polymer precursor compound comprises on average per polymer precursor molecule, -at least 2.0 alkoxysilyl functional groups, with a functionality of at least 2.0, preferably at least 2.5, preferably at least 3.0; and / or -at least 1.0 alkoxysilyl functional groups, with a functionality of at least 3.0; - optionally, an organo-tri-alkoxy silane, an organo-tetra-alkoxy silane, and / or a mixture thereof comprising a metal ion (M+) chelating moiety being a cyanurate, a crown ether, an aza-crown ether, a thia-crown ether, a cryptand, a carbamate, a cyano group, a thiocyanate group, or a metallacrown,, - a metal (M+) salt, preferably does the metal salt comprises Li+, Na+, Mg+, Ca+, Al+, and / or a combination thereof, preferably lithium (Li+); - a solvent, preferably an organic solvent; and, - optionally, an ionically conductive compound; thereby obtaining a solid electrolyte; - optionally, drying the obtained solid electrolyte.

Description

[0001] CROSSLINKED SOLID ELECTROLYTE AND ELECTRODE FOR A SOLID-STATE BATTERY, AND A METHOD FOR

[0002] 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, a solid-state battery, and a method for producing the same.

[0005] BACKGROUND

[0006] Electrochemical power storage devices are widely used in transport applications, ranging from automotive to aviation, marine to space. However, conventional liquid electrolytes are flammable and volatile, adding the risk of fire in the event of a leak. Thus, the development of solid-state batteries containing a solid electrolyte is becoming increasingly important, especially with the ever-growing demand for high energy and safety. In the pursuit of a solid electrolyte with desirable properties, various materials have been considered, including those of organic and inorganic nature such as ceramics, polymers, and gel electrolytes.

[0007] For polymer-based electrolytes specifically, water-based sol-gel chemistry has primarily been used to crosslink the polymers to obtain a solid electrolyte for use in electrochemical power storage devices. However, this approach can be time and resource-consuming. Sol-gel-based chemistry often involves additional processing, making it more challenging to obtain the crosslinked polymer with the desired properties and shape. The presence of water can lead to premature crosslinking of polymer chains, affecting the formation of the desired network structure and resulting in reduced mechanical properties of the solid electrolyte.

[0008] Moreover, water is often an unwanted product in the solid electrolyte as it can interfere with the interactions between the polymer matrix and the electrolyte ions. Consequently, additional drying or dehumidification steps may be required to remove water from the solid electrolyte. However, for dense crosslinked polymers, such drying step can be time-consuming and challenging, as it is important not to thermally deteriorate the crosslinked polymers.

[0009] For example, US 2015 / 256290 Al describes a transfix surface member for use in aqueous ink jet printer comprises a substrate. A conformance layer is disposed on the substrate layer. A surface layer comprising a siloxane polymer network is on the conformance layer. The siloxane polymer network comprises a plurality of diphenylsiloxane moieties and a plurality of polar moieties, the diphenylsiloxane moieties and polar moieties being bonded to the siloxane polymer network by one or more siloxane linkages. WANG HUALAN et al., "Organosilicon-Based Functional Electrolytes for High-Performance Lithium Batteries," Advanced Energy Materials, vol. 11, no. 28, 1 July 2021, XP093237930, DOI: 10.1002 / aenm.202101057; is a review article relating to investigation efforts to developing organosilicon- based electrolytes for the development of liquid, gel, and solid state electrolytes in Li-ion and Li-metal batteries.

[0010] Hence, there is a need to address these limitations by providing a solid electrolyte that has improved mechanical properties without reducing, and advantageously even improving, the ionic conductance. This is advantageous 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 electrolyte should have a fast self-extinguishing time.

[0011] SUMMARY OF THE INVENTION

[0012] The technology of the present disclosure generally relates to the field of power storage devices, and more specifically to a solid electrolyte comprising a crosslinked polymer, optionally including an ionically conductive compound. The crosslinking of the polymer is achieved using alkoxysilyl groups and optionally an organo-tri-alkoxy silane, in the presence of a catalyst in a solvent, preferably an organic solvent.

[0013] An advantage of the present solid electrolyte is its improved mechanical and ionic conductivity properties. Without being bound by theory, the crosslinked functional polymer network may enable the trapping of ionic liquid within the network, thereby reducing or preventing the leakage of ionic liquid from the solid electrolyte in the event of damage such as breakage or crushing. This trapping may further enhance the ionic conductivity of the solid electrolyte when used in a battery, resulting in improved electrochemical performance.

[0014] More specifically, the present solid electrolyte is formed through the use of silane-based crosslinkers as described herein that have a specific multfunctional structure. The present the solid electrolyte comprises one or more compounds selected from organo-tri-alkoxy silanes, organo-tetra-alkoxy silanes, and mixtures thereof, each comprising a metal ion (M+)-chelating moiety. A representative compound is l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lH,3H,5H)-trione (VPS), which includes three silane groups, each bearing three methoxy substituents, thus providing nine alkoxy groups per molecule. These alkoxy groups can undergo hydrolysis and condensation reactions with other alkoxysilane groups to form a highly crosslinked, three-dimensional (3D) polymer network. The resulting 3D crosslinked structure can confer several interrelated advantages. The high crosslink density enhances mechanical robustness and film cohesion, while the reduced polymer segmental mobility contributes to improved thermal and dimensional stability. The inclusion of metal ion (M+)- chelating moieties within the network architecture can facilitate the formation of stable ion transport pathways, enhancing ionic conductivity and supporting effective retention of ionic liquids where present. In addition, the multiplicity of alkoxy groups enables rapid curing under mild processing conditions.

[0015] The combination of these structural and functional features can yields a solid polymer electrolyte with superior performance characteristics, particularly when used in conjunction with polyether-based precursors such as PEG and / or PTHF. The design of the crosslinking agent and its integration into the polymer backbone enable the formation of a mechanically stable, ion-conductive matrix suitable for use in electrochemical energy storage devices.

[0016] Yet another advantage of the present process is the up-scalability and possible precise control of the reaction. The present process may have a notably shorter reaction and preparation time compared to conventional polymerization processes (e.g., water based sol-gel process). Conventional polymerization often involves multiple complex steps such as extensive purification, which can be both time-consuming and resource-intensive. The present process may eliminate the need for such rigorous procedures. Additionally, the present process may not require high-temperature treatment, resulting in lower energy consumption and a reduced CO2footprint during the manufacturing of battery components.

[0017] Yet another advantage of the present solid electrolyte is that the mechanical stability of the produced solid electrolyte and the rapid catalyst curing of the polymer may enable the production of large films through various industrial coating techniques. This robustness and efficiency can support the development of high- quality films at a scale suitable for a wide range of applications, enhancing both performance and sustainability in industrial practices. Moreover, the solid electrolyte may be non-flammable and can have the property to self-extinguish, which are desirable characteristics for battery safety.

[0018] Yet another advantage of the present solid electrolyte is that it may allow for substantially water-free processing and production when implemented in a battery production line. The reduced or substantially water-free environment may improve time and resource efficiency by allowing for better control of the polymer properties and eliminating various processing steps required for handling the presence water, such as drying or dehumidification.

[0019] Yet 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. Yet another advantage of the present solid electrolyte is that it may exhibit improved electrochemical stability.

[0020] Preferred statements (features) and embodiments of the compounds and processes of this invention are now set forth. Each statements and embodiments of the invention so defined may be combined with any other statement and / or embodiments unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

[0021] Numbered statements of this invention are:

[0022] 1. A process for producing a solid electrolyte, comprising the steps of:

[0023] - contacting, in the presence of a catalyst:

[0024] - a polymer precursor compound comprising polyethylene glycol (PEG) and / or polytetrahydrofuran (PTHF), wherein the polymer precursor compound comprises on average per polymer precursor molecule,

[0025] -at least 2.0 alkoxysilyl functional groups, with a functionality of at least 2.0, preferably at least 2.5, preferably at least 3.0; and / or

[0026] -at least 1.0 alkoxysilyl functional groups, with a functionality of at least 3.0;

[0027] - an organo-tri-alkoxy silane, an organo-tetra-alkoxy silane, and / or a mixture thereof,

[0028] - a metal (M+) salt, preferably a lithium (Li+) salt;

[0029] - a solvent, preferably an organic solvent; and,

[0030] - optionally, an ionically conductive compound; thereby obtaining a solid electrolyte;

[0031] - optionally, drying the obtained solid electrolyte.

[0032] 2. The process according to statement 1, wherein the organo-tri-alkoxy silane, an organo-tetra- alkoxy silane comprises a metal ion (M+) chelating moiety.

[0033] 3. The process according to statement 1 or statement 2, wherein the metal ion (M+) chelating moiety is a cyclic moiety or a macrocyclic moiety.

[0034] 4. The process according to any one of previous statements, wherein the metal ion (M+) chelating moiety is a cyanurate, a crown ether, an aza-crown ether, a thia-crown ether, a cryptand, a metallacrown, preferably a cyanurate.

[0035] 5. The process according to any one of previous statements, comprising the steps of: - contacting, in the presence of a catalyst:

[0036] - a polymer precursor compound comprising polyethylene glycol (PEG) and / or polytetrahydrofuran (PTHF), wherein the polymer precursor compound comprises on average per polymer precursor molecule,

[0037] -at least 2.0 alkoxysilyl functional groups, with a functionality of at least 2.0, preferably at least 2.5, preferably at least 3.0; and / or

[0038] -at least 1.0 alkoxysilyl functional groups, with a functionality of at least 3.0;

[0039] -an organo-tri-alkoxy silane, an organo-tetra-alkoxy silane, and / or a mixture thereof comprising a metal ion (M+) chelating moiety being a cyanurate, a crown ether, an aza-crown ether, a thia-crown ether, a cryptand, a carbamate, a cyano group, a thiocyanate group, or a metallacrown,

[0040] - a metal (IVT) salt, preferably does the metal salt comprises Li+, Na+, Mg+, Ca+, AT, and / or a combination thereof, preferably lithium (Li+);

[0041] - a solvent, preferably an organic solvent; and,

[0042] - optionally, an ionically conductive compound; thereby obtaining a solid electrolyte;

[0043] - optionally, drying the obtained solid electrolyte. cess according to any one of previous statements, comprising the steps of:

[0044] - contacting, in the presence of a catalyst:

[0045] - a polymer precursor compound comprising polyethylene glycol (PEG) and / or polytetrahydrofuran (PTHF), wherein the polymer precursor compound comprises on average per polymer przecursor molecule,

[0046] -at least 2.0 alkoxysilyl functional groups, with a functionality of at least 2.0, preferably at least 2.5, preferably at least 3.0; and / or

[0047] -at least 1.0 alkoxysilyl functional groups, with a functionality of at least 3.0;

[0048] -an organo-tri-alkoxy silane, an organo-tetra-alkoxy silane, and / or a mixture thereof comprising a metal ion (M+) chelating moiety being a cyanurate, a crown ether, an aza-crown ether, a thia-crown ether, a cryptand, or a metallacrown,

[0049] - a metal (M+) salt, preferably does the metal salt comprises Li+, Na+, Mg+, Ca+, Al+, and / or a combination thereof, preferably lithium (Li+); - a solvent, preferably an organic solvent; and,

[0050] - optionally, an ionically conductive compound; thereby obtaining a solid electrolyte;

[0051] - optionally, drying the obtained solid electrolyte.

[0052] 7. The process according to any one of previous statements, wherein the crown ether is a 12-crown-

[0053] 4 crown ether or a 15-crown-5 crown ether, preferably a 12-crown-4 crown ether.

[0054] 8. The process according to any one of previous statements, wherein the metal crown is a 12-

[0055] MCFe(lll)N(shi)“4.

[0056] 9. The process according to any one of previous statements, wherein the alkoxysilyl functional groups are functional end groups of the polymer precursor.

[0057] 10. The process according to any one of previous statements, wherein the alkoxysilyl functional groups are tri- alkoxysilyl functional groups.

[0058] 11. The process according to any one of previous statements, wherein the alkoxysilyl functional groups are tri- ethoxysilyl functional groups or tri- methoxysilyl functional groups.

[0059] 12. The process according to any one of previous statements, wherein the organo-tri-alkoxy silane or the organo-tetra-alkoxy silane, are polyfunctional organo-tri-alkoxy silanes or polyfunctional orga no -tetra -alkoxy silanes.

[0060] 13. The process according to any one of previous statements, wherein in the organo-tri-alkoxy silane or the organo-tetra-alkoxy silanes, the one or more tri-alkoxy silane group or the one or more tetra-alkoxy silanes are side chains on the metal ion (M+) chelating moiety.

[0061] 14. The process according to any one of previous statements, wherein the organo-tri-alkoxy silane or the organo-tetra-alkoxy silane 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 (VPS), l,3,5-tris[3-

[0062] (triethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lh,3h,5h)-trione, bis(3-triethoxysilylpropyl)amine, 1,2- bis(triethoxysilyl)ethane, tetraethyl orthosilicate, tetrabutyl orthosilicate, tetrapropyl orthosilicate, (3-aminopropyl)triethoxysilane, triethoxysilylpropyl ethylcarbamate, methyltriethoxysilane, methyltrimethoxysilane, (n,n-diethylaminomethyl)trimethoxysilane, 3- thiocyanatopropyltriethoxysilane, 3-isocyanotopropyltrimethoxysilane, or mixtures thereof.

[0063] 15. The process according to any one of previous statements, wherein the organo-tri-alkoxy silane or the organo-tetra-alkoxy silane 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 (VPS), l,3,5-tris[3-

[0064] (triethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lh,3h,5h)-trione, bis(3-triethoxysilylpropyl)amine, (3- aminopropyl)triethoxysilane, triethoxysilylpropyl ethylcarbamate, (n,n- diethylaminomethyl)trimethoxysilane, 3-thiocyanatopropyltriethoxysilane, 3- isocyanotopropyltrimethoxysilane, or mixtures thereof. The process according to any one of previous statements, wherein the organo-tri-alkoxy silane or the organo-tetra-alkoxy silane 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 (VPS), l,3,5-tris[3- (triethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lh,3h,5h)-trione, triethoxysilylpropyl ethylcarbamate, 3-thiocyanatopropyltriethoxysilane, 3-isocyanotopropyltrimethoxysilane, or mixtures thereof. The process according to any one of previous statements, wherein the organo-tri-alkoxy silane is a l,3,5-tris[3-(trialkoxysilyl)alkyl]-l,3,5-triazine-2,4,6(lh,3h,5h)-trione. The process according to any one of previous statements, wherein the catalyst is a phosphoric acid orga nocatalyst, preferably a phosphoric acid diester. The process according to any one of previous statements, wherein the catalyst is selected from the group comprising dibutyl phosphate (DBuP), diphenyl phosphate (DPP), l,l'-binaphthyl-2,2'- diyl hydrogen phosphate (BNPH) or mixtures thereof. The process according to any one of previous statements, wherein the contacting is done under polymerising conditions. The process according to any one of previous statements, wherein the contacting lasts at least for 15 minutes, preferably at least 30 minutes, preferably at least 45 minutes, preferably at least 60 minutes. The process according to any one of previous statements, wherein the polyethylene glycol (PEG) or the polytetrahydrofuran (PTHF) has a molecular weight of at least 200 to at most 100,000 g / mol, preferably at least 500 to at most 80,000 g / mol, preferably at least 1000 to at most 60,000 g / mol, preferably at least 5000 to at most 40,000 g / mol, preferably at least 10,000 to at most 20,000 g / mol. The process according to any one of previous statements, wherein the metal (M+) salt comprises Li+, Na+, Mg+, Ca+, AT, and / or a combination thereof. The process according to any one of previous statements, wherein the metal salt is selected from the list comprising Lithium bis(trifluoromethanesulfonyl)imide (LiFSI), Lithium bis(trifluoromethane)sulfonimide (LiTFSI), Lithium hexafluorophosphate (LiPFs), Lithium tetrafluoroborate (LiBF4), Lithium bis(oxalato)borate (LiBOB), Lithium difluoro(oxalate)borate (LiODFB), Lithium nitrate (LiNO3), Lithium perchlorate (LiCIO4), and combinations thereof. The process according to any one of previous statements, wherein the solvent is an organic solvent, preferably a polar organic solvent, preferably a polar aprotic solvent. The process according to any one of previous statements, wherein the solvent is water-free. The process according to any one of previous statements, wherein the solvent is acetonitrile, tetrahydrofuran (THF), dimethoxyethane, or a mixture thereof. The process according to any one of previous statements, wherein the ionically conductive compound is an ionic liquid. The process according to any one of previous statements, wherein the ionically conductive compound is l-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIFSI), l-Ethyl-3- methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI), PrMPyrrTf2N, l-Ethyl-3- methylimidazolium trifluoromethanesulfonate (EMIOtf), BMATFSI, EMIB(CN)4, EMITFA, EMIFAP, EMIPFS, EMIBF4, BMPYRFSI, sulfolane, N-methylacetamide, Tetraethylene glycol dimethyl ether, mixtures of 1,3-dioxolane (DOL) and 1,2-dimethoxyethane (DME), and / or a combination thereof. The process according to any one of previous statements, wherein at least 70.0 to at most 100.0 parts by weight of the polymer precursor compound are contacted with:

[0065] - 0.0 to at most 30.0 parts by weight, preferably at least 1.0 to at most 25.0 parts by weight, preferably at least 3.0 to at most 20.0 parts by weight, preferably at least 5.0 to at most 15.0 parts by weight, preferably at least 10.0 to at most 12.0 parts by weight, of the organo-tri-alkoxy silane or the organo-tetra-alkoxy silane;

[0066] - 0.0 to at most 50.0 parts by weight, preferably at least 2.0 to at most 45.0 parts by weight, preferably at least 5.0 to at most 40.0 parts by weight, preferably at least 10.0 to at most 30.0 parts by weight, preferably at least 15.0 to at most 25.0 parts by weight of the ionically conductive compound;

[0067] - 3.0 to 20.0 part by weight, preferably 5.0 to 18.00 parts by weight, preferably 7.0 to 15.00 parts by weight, preferably 10.0 to 12.00 parts by weight, of the metal salt; and,

[0068] - 10.0 to 50.0 part by weight, preferably 15.0 to 45.00 parts by weight, preferably 20.0 to 40.00 parts by weight, preferably 25.0 to 35.00 parts by weight, of the solvent. The process according to any one of previous statements, wherein the water content in the solid electrolyte (after optional drying) is less than 500 ppm, preferably less than 400 ppm, preferably less than 300 ppm, preferably less than 200 ppm, preferably less than 100 ppm. The process according to any one of previous statements, wherein the solid electrolyte after optional drying) is substantially free of water with a water content of less than 50 ppm, preferably less than 40 ppm, preferably less than 30 ppm, preferably less than 20 ppm, preferably less than 10 ppm or less, for example 5 ppm or 0 ppm.

[0069] 33. The process according to any one of previous statements, wherein the process is anhydrous, such that substantially no water is added or included during the step of contacting.

[0070] 34. A solid electrolyte, preferably for an electrochemical energy storage device, obtained by a process according to any one of the statements 1 to 33.

[0071] 35. A solid electrolyte for an electrochemical energy storage device, comprising: a crosslinked polymer, comprising polyethylene oxide (PEG) and / or polytetrahydrofuran (PTHF), covalently crosslinked to via bridging moieties; metal (M+) ions, preferably lithium (Li+) ions; and, optionally, an ionically conductive compound;

[0072] 36. wherein the bridging moieties comprises a -Si-O-Si- bonds, preferably -Si-O-Si-R-Si-O-Si- bonds.The solid electrolyte according to statement 31, wherein metal ion (M+) chelating moieties are covalently bonded or covalently incorporated in the crosslinked polymer.

[0073] 37. The solid electrolyte according to any one of statements 34 to 36, wherein the metal ion (M+) chelating moiety is a cyclic moiety or a macrocyclic moiety.

[0074] 38. The solid electrolyte according to any one of statements 34 to 37, wherein the metal ion (M+) chelating moiety is a cyanurate, a crown ether, an aza-crown ether, a thia-crown ether, a cryptand or a metallacrown.

[0075] 39. A solid electrolyte for an electrochemical energy storage device, comprising: a crosslinked polymer, comprising polyethylene oxide (PEG) and / or polytetrahydrofuran (PTHF), covalently crosslinked to via bridging moieties; metal (M+) ions, preferably lithium (Li+) ions; and, optionally, an ionically conductive compound; wherein the bridging moieties comprise -Si-O-Si- bonds, preferably -Si-O-Si-R-Si-O-Si- bonds; and wherein metal ion (M+) chelating moieties being a cyanurate, a crown ether, an aza-crown ether, a thia-crown ether, a cryptand, a carbamate, a cyano group, a thiocyanate group, or a metallacrown are covalently bonded or covalently incorporated in the crosslinked polymer.

[0076] 40. The solid electrolyte according to any one of statements 34 to 39, wherein the solid electrolyte is impregnated into a membrane. The solid electrolyte according to any one of statements 34 to 40, wherein the water content in the solid electrolyte (after optional drying) is less than 500 ppm, preferably less than 400 ppm, preferably less than 300 ppm, preferably less than 200 ppm, preferably less than 100 ppm. The solid electrolyte according to any one of statements 34 to 41, wherein the solid electrolyte (after optional drying) is substantially free of water with a water content of less than 50 ppm, preferably less than 40 ppm, preferably less than 30 ppm, preferably less than 20 ppm, preferably less than 10 ppm or less, for example 5 ppm or 0 ppm. Use of the solid electrolyte according to any one of statements 34 to 42, as an interelectrode material in an electrochemical energy storage device. An electrode comprising the solid electrolyte according to any one of statements 34 to 42 and an electrode active material. The electrode according to statement 44, wherein the solid electrolyte forms a covering and / or coating layer on the electrode active material. The electrode according to statement 45, wherein the covering layer is a uniform and / or homogenous covering layer with a preferred layer thickness after drying and before compression of below about 200 pm, more preferably below about 150 pm, more preferably still below about 100 pm; more preferably still below about 30 pm or below. The electrode according to any one of statements 44 to 46, wherein electrode has a plurality of pores formed by the electrode active material, thereby forming a porous electrode, and wherein the solid electrolyte penetrates or fills at least a portion of the pores of the porous electrode. The electrode according to any one of statements 44 to 47 wherein the electrode active material is a composite or a metal, preferably a lithium metal. An electrochemical energy storage device, comprising a positive electrode, a negative electrode; and the solid electrolyte according to any one of statements 34 to 42. The electrochemical energy storage device according to statement 49, wherein the solid electrolyte forms a covering and / or coating layer on at least an electrode, preferably at least on the positive electrode. The electrochemical energy storage device according to one of statements 49 or 50, wherein at least one electrode has a plurality of pores, thereby forming a porous electrode, and wherein the solid electrolyte penetrates or fills at least a portion of the pores of the porous electrode, preferably wherein at least the positive electrode is the porous electrode. DESCRIPTION OF THE FIGURES

[0077] 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.

[0078] Figure 1 shows the ionic conductivity (mS / cm) for different electrolyte films according to an embodiment of the invention, as function of the temperature.

[0079] Figure 2 shows the influence of the ionic liquid on the ionic conductivity (mS / cm) for two films according to an embodiment of the invention.

[0080] Figure 3 shows the current density (mA / crri2) versus the potential (V vs Li / Li+) for the solid electrolyte film according to an embodiment of the invention.

[0081] Figure 4 shows the thermal degradations for two solid electrolyte films according to an embodiment of the invention.

[0082] Figure 5 shows ignition time of two solid electrolyte films according to an embodiment of the invention compared to an organic electrolyte.

[0083] Figure 6 shows self-extinction time of two solid electrolyte films according to an embodiment of the invention compared to an organic electrolyte.

[0084] Figure 7 shows the formation test of electrochemical energy storage device cell 1 (Cell 1) of Example 3 according to an embodiment of the invention.

[0085] Figure 8 shows a self-standing film for a solid electrolyte device according to an embodiment of the invention.

[0086] Figure 9 shows the ionic conductivity (mS / cm) for different electrolyte films according to an embodiment of the invention, as function of the concentration of organo-tri-alkoxy silane.

[0087] Figure 10 shows the discharge specific capacity and coulombic efficiency of electrochemical energy storage device cell 2 (Cell 2) of Example 6 according to an embodiment of the present invention, at variable C- discharge and as a function of the number of cycles.

[0088] DETAILED DESCRIPTION

[0089] 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. This description is meant to aid the reader in understanding the technological concepts more easily, but it is not meant to limit the scope of the present disclosure, which is limited only by the claims.

[0090] 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" in various places throughout this specification are not necessarily all referring to the same embodiment.

[0091] As used herein, 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, non-recited members, elements or method steps. The terms "comprising", "comprises" and "comprised of" when referring to recited members, elements or method steps also include embodiments which "consist of" said recited members, elements or method steps. The singular forms "a", "an", and "the" include both singular and plural referents unless the context clearly dictates otherwise.

[0092] Objects described herein as being "connected" or "coupled" reflect a functional relationship between the described objects, that is, the terms indicate the described objects must be connected in a way to perform a designated function which may include a direct or indirect connection in a physical or nonphysical manner, as appropriate for the context in which the term is used.

[0093] 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.

[0094] As used herein, the term "about" is 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. Unless otherwise stated, use of the term "about" 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. The recitation of numerical ranges by endpoints includes all numbers and fractons subsumed within the respective ranges, as well as the recited endpoints. Furthermore, 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.

[0095] 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.

[0096] 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. When describing specific embodiments, reference is made to the accompanying drawings, which are provided solely to aid in the understanding of the described embodiment.

[0097] 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 polymer network, preferably a porous crosslinked polymer network, that may be doped with a metal salt and optionally an ionically conductive compound. The crosslinking is preferably done catalytically, by reacting of alkoxysilyl functional groups on the polymer , optionally with organo-alkoxy silanes, and that preferably in a solvent, preferably an organic solvent.

[0098] The term "solid" as used herein refers to being in solid state as a whole system at room temperature. Partial inclusion of a liquid is not excluded. Gels, for example, are considered "solid". Hence, the "solid electrolyte" as disclosed herein refers to the 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, more specifically, a combination of the composite network and the functionalised polymer. The term "alkoxysilyl functional group" refers to a functional group which may be considered as the radical of silane, wherein one or more alkoxy groups are bond to the silicon atom. The alkoxysilyl functional group may be a (mono-alkoxy)silyl functional group, however of particular interest in the disclosure are the (di- alkoxy)silyl functional groups, which can be represented by formula (V); and the (tri-alkoxy)silyl functional groups, which can be represented by formula (VI):

[0099] Preferably, R4, R5, R6are alkyl or aryl, preferably with at most 10 carbon atoms, preferably at most 8 carbon atoms, preferably at most 6 carbon atoms, preferably at most 4 carbon atoms, and preferably at most 2 carbon atoms. Preferably, R7is an alkyl or aryl, preferably with at most 10 carbon atoms, preferably at most 8 carbon atoms, preferably at most 6 carbon atoms, preferably at most 4 carbon atoms, and preferably at most 2 carbon atoms. It should be noted that for the formation of the crosslinked polymer as described herein, alkoxy groups are reactive functional groups that can participate in the network formation. Alkyl groups typically do not participate in the network formation, resulting in unreacted, dangling chain ends within the polymeric structure.

[0100] In an aspect the invention relates to a process for producing a solid electrolyte.

[0101] In particular embodiments, the process comprises the steps of:

[0102] - contacting, in the presence of a catalyst:

[0103] - a polymer precursor compound comprising polyethylene glycol (PEG) and / or polytetrahydrofuran (PTHF), wherein the polymer precursor compound comprises on average per polymer precursor molecule,

[0104] -at least 2.0 alkoxysilyl functional groups, with a functionality of at least 2.0, preferably at least 2.5, preferably at least 3.0; and / or

[0105] -at least 1.0 alkoxysilyl functional groups, with a functionality of at least 3.0;

[0106] -an organo-(tri-alkoxy)silane, an organo-(tetra-alkoxy)silane, and / or a mixture thereof,

[0107] - a metal (M ) salt, preferably a lithium (Li ) salt; - a solvent, preferably an organic solvent; and,

[0108] - optionally, an ionically conductive compound; thereby obtaining a solid electrolyte;

[0109] - optionally, drying the obtained solid electrolyte.

[0110] In particular embodiments, the process comprises the steps of:

[0111] - contacting, in the presence of a catalyst:

[0112] - a polymer precursor compound comprising polyethylene glycol (PEG) and / or polytetrahydrofuran (PTHF), wherein the polymer precursor compound comprises on average per polymer przecursor molecule,

[0113] -at least 2.0 alkoxysilyl functional groups, with a functionality of at least 2.0, preferably at least 2.5, preferably at least 3.0; and / or

[0114] -at least 1.0 alkoxysilyl functional groups, with a functionality of at least 3.0;

[0115] -an organo-tri-alkoxy silane, an organo-tetra-alkoxy silane, and / or a mixture thereof comprising a metal ion (M+) chelating moiety being a cyanurate, a crown ether, an aza-crown ether, a thia-crown ether, a cryptand, a carbamate, a cyano group, a thiocyanate group, or a metallacrown,

[0116] - a metal (IVT) salt, preferably does the metal salt comprises Li+, Na+, Mg+, Ca+, AT, and / or a combination thereof, preferably lithium (Li+);

[0117] - a solvent, preferably an organic solvent; and,

[0118] - optionally, an ionically conductive compound; thereby obtaining a solid electrolyte;

[0119] - optionally, drying the obtained solid electrolyte.

[0120] As used herein the term "functionality", may read on the functionality of the functional group, in particular the functionality of the alkoxysilyl functional group. It expresses the average amount of functionalities per function group, hence in this case the amount of alkoxy groups bound to the silicon atom of the silyl functional group.

[0121] The present process has the advantage that the formation of the solid electrolyte may occur fast, so that shaping of the solid electrolyte may become easier as long gelation times may be avoided.

[0122] The process is very flexible in reaction conditions. So may an inert atmosphere be avoided, or may there be no need to work under dry conditions. In some embodiments, the contacting is done under polymerising conditions. The process provides a solid electrolyte that has great mechanical properties, like a low brittleness, hight elasticity and high strength; while remaining or even improving the ionic conductivity of the solid electrolyte compared to a polyethylene glycol (PEG) or a polytetrahydrofuran (PTHF) electrolyte. It appears that the formed -Si-O-Si- bonds and or the residues of the organo-tri-alkoxy silane and the organo-tetra-alkoxy silane allow easy mobility of the metal ions over the crosslinking moiety. The functionality of the alkoxysilyl functional groups may allow cross-linking of the polymer precursor compound, as these functional groups may react between themselves, or when present with the silyl alkoxy groups of the organo-tri-alkoxy silane or organo-tetra-alkoxy silane. The organo-tri-alkoxy silane or organo-tetra-alkoxy silane may therefore function as a crosslinking agent. When an ionically conductive compound, such as an ionic liquid, it may be embedded in said three-dimensional network, so that a solid electrolyte is obtained.

[0123] In some embodiments, the polymer precursor compound, the organo-tri-alkoxy silane when present, and organo-tetra-alkoxy silane when present are mixed together before being contacted with the catalyst.

[0124] In some embodiments, the organo-tri-alkoxy silane, an organo-tetra-alkoxy silane comprises a metal ion (M+) chelating moiety. It has been found that the incorporation of a metal ion (M+) chelating moiety in the organo-tri-alkoxy silane or the organo-tetra-alkoxy silane, may establish a crosslink between the polymer precursor molecules that may increase the mobility of metal ions, thereby increasing the conductivity of the solid electrolyte.

[0125] As used herein, the term silane compound specifically comprising an organo-trialkoxysilane, an organo- tetraalkoxysilane, and / or a mixture thereof refers to a compound that includes at least one silane selected from: an organo-trialkoxysilane, of the general formula R-Si(OR')3, and / or an organo-tetraalkoxysilane, of the general formula Si(0R')4, wherein R is an organic substituent, such as an alkyl, aryl, or functionalised hydrocarbon group, and OR' is an alkoxy group, such as methoxy or ethoxy. Preferably, the silane compound may consist of a single species or a mixture of two or more species, and may optionally comprise additional functional groups, including, but not limited to, groups capable of participating in cross-linking reactions or chelating metal ions (M+) as defined herein.

[0126] 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. In some embodiments, the metal ion (M+) chelating moiety is a cyclic moiety or a macrocyclic moiety. These may provide a certain rigidity to the organo-tri-alkoxy silane, organo-tetra-alkoxy silane or the formed solid electrolyte, which may increase the speed of reaction or the mechanical properties of the solid electrolyte. In some embodiments, the metal ion (M+) chelating moiety is a cyanurate, a crown ether, an aza-crown ether, a thia-crown ether, a cryptand, a metallacrown, preferably a cyanurate or a crown ether.

[0127] As used herein, the term cyanurate refers to derivatives of cyanuric acid, which is represented by the equilibrium (I):

[0128] Typically derivatization may occur on the nitrogen atoms of cyanuric acid. Hence a cyanurate may be represented by formula (II):

[0129] (ii).

[0130] Wherein -R1, -R2, -R3are typically (alkoxy silane)alkyl groups, preferably (dialkoxy silane)alkyl groups or (trialkoxy silane)alkyl groups, preferably (trialkoxy silane)alkyl groups. Preferably, each -R1, -R2, -R3, comprises at most 15 carbon atoms, preferably at most 12 carbon atoms, preferably at most 10 carbon atoms, preferably at most 9 carbon atoms, preferably at most 6 carbon atoms. Preferably the alkoxy groups are methoxy groups or ethoxy groups. Cyanurate may have the ability of chelating metal ions, particularly lithium (Li+) ions.

[0131] In some embodiments, the crown ether is a 12-crown-4 crown ether or a 15-crown-5 crown ether, preferably a 12-crown-4 crown ether. In some embodiments, the metallacrown is a 12-M CFe(m)N(shi)-4. These crown ethers may chelate smaller metal ions, such as Li+ions.

[0132] In some embodiments, the alkoxysilyl functional groups are functional end groups of the polymer precursor. This has the advantage that the number of function groups per polymer precursor group 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.

[0133] The terms "functional end group", "reactive end group", and "terminal reactive group" as used herein refers to a substituent or moiety that is positioned at an extremity of a macromolecule or oligomer molecule (e.g., a polymer precursor compound). Said substituent or moiety is capable of entering into further polymerization or other reactions. A polymer functionalized with at least one reactive group is therefore suitable for reaction with a given compound, bearing at least one complementary reactive functional group. Preferably, in the present disclosure, both functional end groups of the polymer precursor are alkoxysilyl functional groups, preferably both (di-alkoxy)silyl functional groups or both (trial koxy)silyl functional groups, more preferably both (tri-alkoxy)silyl functional groups.

[0134] In some embodiments, the polymer precursor compound comprises two reactive functional end groups, according to the following formula (VII): wherein

[0135] - TG is a reactive functional end group selected from the group consisting of (di-alkoxy)silyl, or (tri- alkoxyjsilyl, and combinations thereof;

[0136] - R is an alkyl group, and

[0137] - n ranges from 6 to 13000, preferably 6 to 10000, more preferably 6 to 5000, more preferably still 6 to 1000, more preferably still 6 to 500, more preferably still 6 to 150.

[0138] In some embodiment, the alkoxysilyl functional groups are (tri- a I koxy)sily I functional groups. This provides functional groups with a high functionality, which provides a high availability of reactive species, allowing easy crosslinking and / or a high crosslinking density of the polymer precursor compound.

[0139] In some embodiment, the alkoxysilyl functional groups are tri- ethoxysilyl functional groups or trimethoxysilyl functional groups. The alkoxy groups being methoxy groups or ethoxy groups provides in a high atom-efficiency in the formation of the solid electrolyte. The choice of alkoxy groups may also influence the reactivity of the functional groups.

[0140] In some embodiment, the organo-tri-alkoxy silane or the orga no -tetra -alkoxy silane, are polyfunctional organo-tri-alkoxy silanes or polyfunctional orga no -tetra -alkoxy silanes. As used herein, the prefix "poly-", may refer to more than one. When the organo-tri-alkoxy silane, comprises ate least two tri-alkoxy silanes, the availability of crosslinkable groups increases, which may result in easier, faster crosslinking reaction or result in a higher crosslinking density.

[0141] In some embodiments, in the organo-tri-alkoxy silane or the organo-tetra-alkoxy silanes, the one or more tri-alkoxy silane group or the one or more tetra-alkoxy silanes are side chains on the metal ion (M+) chelating moiety. This way, 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.

[0142] In some embodiments, the organo-tri-alkoxy silane or the organo-tetra-alkoxy silane 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 (VPS), 1,3,5- tris[3-(triethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lh,3h,5h)-trione, bis(3-triethoxysilylpropyl)amine, 1,2- bis(triethoxysilyl)ethane, tetraethyl orthosilicate, tetrabutyl orthosilicate, tetrapropyl orthosilicate, (3- aminopropyl)triethoxysilane, triethoxysilylpropyl ethylcarbamate, methyltriethoxysilane, methyltrimethoxysilane, (n,n-diethylaminomethyl)trimethoxysilane, 3-thiocyanatopropyltriethoxysilane, 3-isocyanotopropyltrimethoxysilane, or mixtures thereof.

[0143] In some embodiments, the organo-tri-alkoxy silane or the organo-tetra-alkoxy silane 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 (VPS), 1,3,5- tris[3-(triethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lh,3h,5h)-trione, bis(3-triethoxysilylpropyl)amine, (3- aminopropyl)triethoxysilane, triethoxysilylpropyl ethylcarbamate, (n,n- diethylaminomethyl)trimethoxysilane, 3-thiocyanatopropyltriethoxysilane, 3- isocyanotopropyltrimethoxysilane, or mixtures thereof.

[0144] In some embodiments, the organo-tri-alkoxy silane or the organo-tetra-alkoxy silane 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 (VPS), 1,3,5- tris[3-(triethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lh,3h,5h)-trione, triethoxysilylpropyl ethylcarbamate, 3- thiocyanatopropyltriethoxysilane, 3-isocyanotopropyltrimethoxysilane, or mixtures thereof.

[0145] In some embodiments, the organo-tri-alkoxy silane is a l,3,5-tris[3-(trialkoxysilyl)alkyl]-l,3,5-triazine- 2,4,6(lh,3h,5h)-trione.

[0146] As used herein, l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,5(lh,3h,5h)-trione, also known as VPS, and is a molecule which can be represented by formula (III): 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.

[0147] 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 (IV): iiV) 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 1,3,5-Tris(triethoxysilylpropyl) isocyanurate; Tris(3-triethoxysilylpropyl) isocyanurate. Th compound is also a cyanurate within the meaning of this application.

[0148] In some embodiments, the catalyst is a phosphoric acid orga no catalyst. In some embodiments, the catalyst is selected from the group phosphoric acid diester, dibutyltin dilaurate, imidazoles, tetrabutyl titanate, zirconium propoxide, p-toluenesulfonic acid, triethylamine, imidazoles, any substitutions known in the art, and / or a combination thereof; more preferably at least phosphoric acid diester. In some embodiments, the catalyst is selected from the group comprising dibutyl phosphate (DBuP), diphenyl phosphate (DPP), l,l'-binaphthyl-2,2'-diyl hydrogen phosphate (BNPH), or mixtures thereof. It has been found that such catalyst results in a fast polymerisation reaction.

[0149] In some embodiments, the contacting lasts at least for 15 minutes, preferably at least 30 minutes, preferably at least 45 minutes, preferably at least 60 minutes.

[0150] In some embodiments, the contacting can be performed at a temperature of at most 70 °C to at least 0 °C, preferably at most 60 °C to at least 5 °C, more preferably at most 55 °C to at least 10 °C, more preferably at most 50 °C to at least 15 °C, more preferably at most 45 °C to at least 20 °C, more preferably still about room temperature. The listed temperatures can decrease the time needed for polymer network to form, although lower temperatures can be considered still.

[0151] In some embodiments, after the contacting step, the solid electrolyte can be dried. The drying can be performed by a classic drying and / or ageing process, e.g., by UV or convector, online or static. For example, the obtained mixture can be dried, for example, 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 be carried out before the vacuum drying step to reduce occurrence of bumping and generation of air bubbles during the vacuum drying. In the pre-drying process, the obtained mixture 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 organic solvent contained in the obtained mixture can be evaporated by the pre-drying process.

[0152] In some embodiments, the solid electrolyte can be impregnated into the pores of electrode layer, for example during the contacting step.

[0153] In some embodiment, the contacting step may be performed after the reaction mixture is blade coated on the electrode layer, the resultant crosslinked polymer is formed into the pores of the active electrode. In some embodiments, the polyethylene glycol (PEG) or the polytetrahydrofuran (PTHF) has a molecular weight of at least 200 to at most 100,000 g / mol, preferably at least 500 to at most 80,000 g / mol, preferably at least 1000 to at most 60,000 g / mol, preferably at least 5000 to at most 40,000 g / mol, preferably at least 10,000 to at most 20,000 g / mol. This may be a balance between the polymer being long enough for a good ion mobility and a density of crosslinking enough to provide the desired mechanical properties.

[0154] The terms "matrix" and "network" are used herein interchangeably and denote a three-dimensional crosslinked polymeric structure, wherein the polymer chains are bonded together by covalent links.

[0155] The herein disclosed crosslinked polymer can be produced through the reaction of a polymer precursor compound among themselves or together with the organo-tri-alkoxy silane or the organo-tetra-alkoxy silane, in order to form an in-situ siloxane-network that is covalently grafted with the functionalised polymer chains.

[0156] The term "in-situ" as used herein denotes that the network is an inorganic-organic hybrid network comprising inorganic segments and organic segments that are comprised in the backbone and / or sidechains of the cross-linked polymeric structure. Hence, the functionalised polymer chains may be incorporated (i.e., covalently bound) into the polymer backbone and / or sidechains. The in-situ formation of the composite network can improve the flexibility of the solid electrolyte. Specifically, the presence of functionalised polymer chains grafted inside the siloxane may allow the composite network to reorganize and fill the solvent place when it is evaporated and form a uniform electrolyte film free of cracks. Hence, allowing the possibility of coating on substrates of any size and over large areas.

[0157] In particular embodiments, the network is an inorganic-organic hybrid network, preferably comprising a copolymer of the alkoxide compound and the polymer precursor compound.

[0158] The term "copolymer" as used herein refers to polymers formed by the polymerization of at least two different monomers or macromers. Copolymers can be linear and nonlinear (i.e., branched) depending on the number of reactive functional groups present in each monomer. Typically, monomers having two functional groups mainly result in linear copolymers, while monomers having more than two functional groups mainly yield branched copolymers. When the polymer chains of the branched copolymers become covalently bound (beyond the gel point), a three-dimensional cross-linked network is typically formed.

[0159] It should be understood that the herein disclosed monomers (i.e., an organo-alkoxy-silane and a polymer precursor compound) typically comprise more than two reactive functionalities, allowing the formation of branched copolymeric structures.

[0160] In some embodiments, the network may comprise branched copolymers, and more particularly graft copolymers, wherein the main chain primarily comprises (inorganic) siloxane, and wherein the side chains primarily comprise the functionalized (organic) polymer chains.

[0161] The formed polymer chains are part of functionalised compound that can be included as a second silica precursor (i.e., monomer) in the electrolyte system. Without wishing to be bound by theory, when the composite network is formed, the polymer chains can be grafted directly within the porous silica that can improve the material flexibility, help to control rheological properties and to reduce hardness in highly filled silica system, such that a uniform electrolyte film can be formed free of cracks, as described later. Moreover, the composite network can act as a reinforcing agent, providing further mechanical compliance and structural integrity under compression process because the cross-linking may create a more interconnected structure, which may distribute stress more evenly and may enhance the material's ability to withstand mechanical forces without deforming, may increase the heat distortion temperature allowing the polymer to maintain its shape and performance at higher temperatures, higher plateau modulus indicating improved stiffness and elasticity over a range of temperatures. The interlocking network may limit the polymer chains' movement, thereby reducing the thermal expansion coefficient and minimizing dimensional changes with temperature fluctuations. These benefits may arise due to the polymer network's ability to accommodate volume variations during cycling, such as those experienced when lithium is used as an anode.

[0162] In this way, a combination of a functionalised polymer with the inorganic composite network 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 above referenced document, 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.

[0163] 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.

[0164] Also, the presence of functionalised polymer chains can lead to strong dissociation of the dissolved metal salts, allowing ions to diffuse inside the network due to the strong interaction between oxygen atoms of the polymer and ion, resulting in a more relaxed coordination between oxygen atoms and lithium ions and thereby facilitating the transport of ions through the composite network which can improve the ion conductivity of the solid electrolyte so that it is suitable for manufacturing of a high energy solid-state battery, as described later. Several functional groups of VPS that used in some embodiments as trifunctional crosslinker may positively impact cross-linked polymer electrolyte. The carbonyl groups may coordinate with lithium ions and promote ion mobility. These groups may act as Lewis acid or Lewis base sites, facilitating the complexation of lithium ions. Nitrogen atoms may also participate in ion coordination. This polymers with nitrogen-containing functional groups may provide pathways for lithium-ion transport by interacting with the ions. These functional groups, including carbonyl groups and nitrogen atoms, may contribute to the overall ionic conductivity of the cross-linked polymer electrolyte. Their presence may create a more conducive environment for lithium-ion transport, making them valuable in the design and optimization of polymer electrolytes for lithium batteries. The specific choice of functional groups and their concentration depends on the desired properties and the compatibility with other components of the battery system. Lithium ions may coordinate with carbonyl groups in the polymer, while ethylene oxide groups may trap the lithium ions, making their diffusion more difficult through the polymer.

[0165] In an embodiment, the solid electrolyte may comprise a crosslinked polymer comprising polyethylene glycol (PEG), covalently grafted via siloxane comprising crosslinking moieties. PEG has an ethylene oxide group that is advantageous for a solid electrolyte due to its higher ionic conductivity for ions. Preferably, PEG comprises bi-terminal reactive functional groups, for example, alkoxysilyl groups, preferably (di- alkoxy)silyl or (tri-alkoxy)silyl as a terminal reactive functional group.

[0166] In an embodiment, the solid electrolyte may comprise a crosslinked polymer comprising polytetrahydrofuran (PTHF), covalently grafted via siloxane comprising crosslinking moieties. PTHF has an ethylene oxide group that is advantageous for a solid electrolyte due to its higher ionic conductivity for ions. Preferably, PTHF comprises bi-terminal reactive functional groups, for example, alkoxysilyl groups, preferably (di-alkoxy)silyl or (tri-alkoxy)silyl as a terminal reactive functional group.

[0167] In some embodiments, the amount of PEG and / or PTHF, is at least 1 wt.% to at most 15 wt.% with respect to the total weight of the solid electrolyte. The listed amounts are optimal for improving the flexibility of the solid electrolyte with the silane terminated polymer.

[0168] In certain embodiments, the amount of polymer precursor compound in the solid electrolyte as described herein is at least 3 wt.% to at most 15 wt.% with respect to the total weight of the electrolyte. It has been found that this may provide an optimal balance between flexibility and integrity of the solid electrolyte.

[0169] In some embodiments, the polymer precursor compound may comprise combination of two or more polymer compounds comprising a different alkoxysilyl functional groups.

[0170] In certain embodiments, the process as described herein is anhydrous, meaning that substantially no water is added during the process. This may have the advantage of reducing the need for substantial water removal following the formation of the solid electrolyte. In particular, some applications of the solid electrolyte do not permit the presence of substantial amounts of water. Consequently, it is advantageous that the present process does not necessitate the addition of water either to initiate the process or as a solvent. Therefore, in some embodiments, the solvent employed is substantially free of water. However, it is understood by those skilled in the art that, due to specific processing conditions, there may be a possibility of incidental moisture being present in the solid electrolyte. Accordingly, the suitable water content is defined as specified in the embodiments below.

[0171] In certain embodiments the water content in the solid electrolyte (after an optional drying step) is less than 500 ppm, preferably less than 400 ppm, preferably less than 300 ppm, preferably less than 200 ppm, preferably less than 100 ppm. In certain preferred embodiments the solid electrolyte (after an optional drying step) is substantially free of water with a water content of less than 50 ppm, preferably less than 40 ppm, preferably less than 30 ppm, preferably less than 20 ppm, preferably less than 10 ppm or less, for example 5 ppm or 0 ppm.

[0172] In some embodiments, the solvent is an organic solvent, preferably a polar organic solvent, preferably a polar aprotic solvent. In some embodiments, the solvent is acetonitrile, tetrahydrofuran (THF), dimethoxyethane, or a mixture thereof. The solvent may aid in the mixing and dispersion of the polymer precursor compound, the ionic liquid electrolyte (ILE), and the organo-alkoxysilane compound. Moreover, the solvent may alter the viscosity of the mixture and thereby provide easier handling and processing of the mixture to form the solid electrolyte composition.

[0173] In some embodiments, the ionically conductive compound is an ionic liquid. This may increase the conductivity of the solid electrolyte, without introducing water into the solid electrolyte.

[0174] As mentioned before, the solid electrolyte can be produced with an ionic liquid as an electrolyte. As used herein, "ionic liquids" refers to salts that have a low melting point such that it is liquids at room temperature, comprising a cation and an anion dissolved in a solvent, which depending on the exact anion / cation combination, can be used as electrolytes for energy storage applications.

[0175] As will be discussed later, one or more ionically conductive compounds, such as an ionic liquid but also alternatives, such as sulfolane, N-methylacetamide, tetraethylene glycol dimethyl ether, and the like, could be added to the reaction mixture in order to improve the ionic conductivity. Liquid additives with low flammability 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.

[0176] In some embodiments, the ionically conductive compound is l-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIFSI), l-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI), PrMPyrrTf2N, l-Ethyl-3-methylimidazolium trifluoromethanesulfonate (EMIOtf), BMATFSI, EMIB(CN)4, EMITFA, EMIFAP, EMIPFs, EMIBF4, BMPYRFSI and / or a combination thereof, sulfolane, N- methylacetamide, Tetraethylene glycol dimethyl ether, mixtures of 1,3-dioxolane (DOL) and 1,2- dimethoxyethane (DME), and / or a combination thereof. With the use of EMIFSI, a solid electrolyte can have improved cycle characteristics, rate characteristics, and low-temperature characteristics. Nonetheless, other combinations of conductive compound and metal salts may be considered, as described below.

[0177] In some embodiments, the metal (M+) salt comprises 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+.

[0178] In some embodiments the amount of dissolved metal salt may be at least 10 wt.% to at most 20 wt.% with respect to the total weight of the solid electrolyte. Preferably, the amount of dissolved Li salt in the solid electrolyte may be at least 10 wt.% to at most 20 wt.% with respect to the total weight of the solid electrolyte. The listed amounts are advantageous for the manufacturing of a solid-state battery having improved ionic conduction properties.

[0179] In some embodiment the amount of dissolved metal salt concentration may be at least 1 Mol / I to at most 2 Mol / I. Preferably, the amount of dissolved LiTFSI may be at least 1 Mol / I to at most 2 Mol / L Preferably, embodiment the amount of dissolved Li salt concentration may be at least 1 Mol / I to at most 2 Mol / I. Preferably, the amount of dissolved LiTFSI may be at least 1 Mol / I to at most 2 Mol / I. The listed amounts are advantageous for the manufacturing of a solid-state battery having improved ionic conduction properties.

[0180] Alternatively or in combination, the lithium salt may comprise one or more other cations, such as Lithium bis(trifluoromethanesulfonyl)imide (LiFSI), Lithium bis(trifluoromethane)sulfonimide (LiTFSI), Lithium hexafluorophosphate (LiPFs), Lithium tetrafluoro bo rate (Li BF4), 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 an organic solvent. Additionally, a plurality of different metal salts may be used, for example, LiFSI and LiTFSI.

[0181] In some embodiments, the ionically conductive compound may comprise at least one of an ionic liquid, including l-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIFSI), l-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI), PrMPyrrTf2N, l-Ethyl-3-methylimidazolium trifluoromethanesulfonate (EMIOtf), BMATFSI, EMIB(CN)4, EMITFA, EMIFAP, EMIPFs, EMIBF4, BMPYRFSI and / or a combination thereof, sulfolane, N-methylacetamide, Tetraethylene glycol dimethyl ether, mixtures of 1,3-dioxolane (DOL) and 1,2-dimethoxyethane (DME), and / or a combination thereof.

[0182] In some embodiments the amount of ionically conductive compound in the solid electrolyte may be at least 1 wt.% to at most 50 wt.% with respect to the total weight of the solid electrolyte. In some embodiments, a molar ratio of the ionic liquid to the crosslinked polymer is at least 0.5 and at most 3 (ionic liquid to polymer). The listed amounts are advantageous for the manufacturing of a solid-state battery having improved ionic conduction properties. 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.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] 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.

[0187] 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 layers 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. 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.

[0188] 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 (AI2Si2O5(OH)4), preferably from natural nano-clay.

[0189] 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 (tu+) 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.

[0190] 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.

[0191] 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.

[0192] 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 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 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.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] In some embodiments, the phosphate salt may comprise an ammonium ion (NH4+, cation) and / or an organoammonium ion (cation).

[0199] 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. 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.

[0200] 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.

[0201] 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.

[0202] 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.

[0203] 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.

[0204] 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.

[0205] In some embodiments, at least 70.0 to at most 100.0 parts by weight of the polymer precursor compound are contacted with at least 0.0 to at most 30.0 parts by weight, preferably at least 1.0 to at most 25.0 parts by weight, more preferably at least 3.0 to at most 20.0 parts by weight, more preferably at least 5.0 to at most 15.0 parts by weight, and most preferably at least 10.0 to at most 12.0 parts by weight, of the organo- tri-alkoxy silane, the organo-tetra-alkoxy silane, and / or mixtures thereof.

[0206] In some embodiments, at least 70.0 to at most 100.0 parts by weight of the polymer precursor compound are contacted with at least 0.0 to at most 50.0 parts by weight, preferably at least 2.0 to at most 45.0 parts by weight, more preferably at least 5.0 to at most 40.0 parts by weight, more preferably at least 10.0 to at most 30.0 parts by weight, and most preferably at least 15.0 to at most 25.0 parts by weight, of the ionically conductive compound.

[0207] In some embodiments, at least 70.0 to at most 100.0 parts by weight of the polymer precursor compound are contacted with at least 3.0 to at most 20.0 parts by weight, preferably 5.0 to 18.0 parts by weight, more preferably 7.0 to 15.0 parts by weight, and most preferably 10.0 to 12.0 parts by weight, of the metal salt.

[0208] In some embodiments, at least 70.0 to at most 100.0 parts by weight of the polymer precursor compound are contacted with at least 10.0 to at most 50.0 parts by weight, preferably 15.0 to 45.0 parts by weight, more preferably 20.0 to 40.0 parts by weight, and most preferably 25.0 to 35.0 parts by weight, of the solvent.

[0209] For the avoidance of doubt, all combinations of the ranges, values, for the above listed components are considered to be explicitly disclosed as part of the present application. In another aspect, the invention provides for a solid electrolyte, preferably for an electrochemical energy storage device, obtained by a process according to an embodiment described herein.

[0210] Particularly, the invention may provide in a solid electrolyte for an electrochemical energy storage device, comprising: a crosslinked polymer, comprising polyethylene oxide (PEG) and / or polytetrahydrofuran (PTHF), covalently crosslinked to via bridging moieties; metal (M+) ions, preferably lithium (Li+) ions; and, optionally, an ionically conductive compound; wherein the bridging moieties comprises a -Si-O-Si- bonds, preferably -Si-O-Si-R-Si-O-Si- bonds.

[0211] In some embodiments, metal ion (M+) chelating moieties are covalently bonded or covalently incorporated in the crosslinked polymer.

[0212] In particular embodiments, the invention may provide a solid electrolyte for an electrochemical energy storage device, comprising a crosslinked polymer, comprising polyethylene oxide (PEG) and / or polytetrahydrofuran (PTHF), covalently crosslinked to via bridging moieties; metal (M+) ions, preferably lithium (Li+) ions; and, optionally, an ionically conductive compound; wherein the bridging moieties comprise -Si-O-Si- bonds, preferably -Si-O-Si-R-Si-O-Si- bonds; and wherein metal ion (M+) chelating moieties being a cyanurate, a crown ether, an aza-crown ether, a thia-crown ether, a cryptand, a carbamate, a cyano group, a thiocyanate group, or a metallacrown are covalently bonded or covalently incorporated in the crosslinked polymer.

[0213] In some embodiments, the thickness of the solid electrolyte is 25 pm to 100 pm, preferably 30 pm to 75 pm, 40 pm to 50 pm.

[0214] In some embodiments, the ionic conductivity at 100°C of the solid electrolyte is 0.30 mS / cm to 2.00 mS / cm, preferably 0.40 mS / cm to 1.50 mS / cm, preferably 0.50 mS / cm to 1.00 mS / cm.

[0215] In some embodiments, the electrochemical stability window of the solid electrolyte is at least 1.0 V, preferably at least 2.0 V, preferably at least 3.0 V, preferably at least 3.5 V, preferably at least 4.0 V, preferably at least 4.5 V.

[0216] In some embodiments, the thermal stability at 5% weight loss of the solid electrolyte is at least 150 °C, preferably; at least 175 °C, preferably at least 200 °C, preferably at least 220 °C. In some embodiments, the ignition time of the solid electrolyte is at least 5 seconds, preferably at least 7 seconds, preferably at least 10 seconds, preferably at least 12 seconds, preferably at least 50 seconds, preferably at least 100 seconds, preferably at least 150 seconds, preferably at least 190 seconds.

[0217] In some embodiments, the solid electrolyte self-extinguishes after at most 60 seconds, preferably at most 45 seconds, preferably at most 30 seconds, preferably at most 15 seconds.

[0218] In another aspect, the invention provides in the use of the solid electrolyte according to an embodiment disclosed herein, as an inter-electrode material in an electrochemical energy storage device.

[0219] In another aspect, the invention provides an electrode comprising the solid electrolyte according to an embodiment disclosed herein, and an electrode active material. In this way, a composite electrode can be obtained. In some embodiments, the solid electrolyte forms a covering and / or coating layer on the electrode active material.

[0220] 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.

[0221] Subsequently, the electrode active material can be impregnated, for example, by applying a solid electrolyte precursor solution (the reaction mixture) and / or 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.

[0222] 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.

[0223] 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.

[0224] 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.

[0225] 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.

[0226] 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.

[0227] 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.

[0228] 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.

[0229] 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. 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 selfstanding 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).

[0230] 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.

[0231] 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, LiNiOz, LiMnO2, LiMn2O4, LiNiCoMnCh (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 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 LiMnogFeo iP04, LiMnosFeo2P04, LiMno.7Feo.3PC , LiMno.5Feo5PC and the like) Li2NiSiO4, Li2CoSiO4, Li2MnSiO4, Li2FeSiO4, LiNiBOs, LiCoBCU, LiMnBOs, and LiFeBCU. Examples of the lithium-containing transition metal sulfide include LiTiSz, 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.

[0232] 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, SiO, SnBPOs, 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.

[0233] 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.

[0234] In some embodiments, the solid electrolyte may penetrate the porosity of the electrode. It may therefore reduce the porosity of the electrode. In some embodiments, the solid electrode overfills the pores of the electrode; which may improve the interface contact.

[0235] Another aspect of the present disclosure relates to a method for producing an electrode, comprising the steps: providing an electrode active material; and forming a covering / coating layer comprising a solid electrolyte according to any of herein described embodiments on the electrode active material.

[0236] 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.

[0237] 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. 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).

[0238] 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.

[0239] 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 the solid electrolyte according to any of the above embodiments. 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.

[0240] 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.

[0241] 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.

[0242] EXAMPLES

[0243] 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.

[0244] Throughout the examples, the following abbreviations are used: 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; stainless steel (SUS); lithium ferro-phosphate (LFP); thermal gravimetric analysis (TGA); scanning electron microscope (SEM); electrochemical impedance spectroscopy (EIS); Linear sweep voltammetry (LSV); Electrochemical stability window (ESW).

[0245] Example 1: solid electrolyte comprising ionic liquid

[0246] A mixture was prepared comprising:

[0247] 57.5 parts by weight of bis(3-t riethoxysily I propyl ) polyethylene oxide (SPEG), with a molecular weight of approximately 1600 g / mol;

[0248] 5.5 parts by weight of l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lH,3H,5H)-trione (VPS);

[0249] 1.0 parts by weight of dibutyl phosphate;

[0250] 30.0 parts by weight of EMIFSI (ionic liquid )

[0251] 6 parts by weight of a LiTFSI; dissolved in acetonitrile as solvent, used in a 1 to 1 weight ratio compared to the SPEG.

[0252] The mixture was stirred for 3 minutes, blade coated and left to polymerise for 1 hour at room temperature. The resulting polymer was dried at 100 °C for 2 hours under vacuum, to yield the dried solid electrolyte. A flexible film was obtained with an area of at least 119 cm2, and a thickness of 70 pm. The water content of the film was less than 100 ppm.

[0253] The ionic liquid was incorporated into the flexible film of the solid electrolyte. The mechanical properties of the film were assessed by subjecting it to a crushing test using an automated electric press, applying a pressure of approximately 25 MPa. It was observed that no liquid came out of the film, even after crushing. This test demonstrates that the ionic liquid is effectively retained within the cross-linked functional polymer network.

[0254] The ionic conductivity of the obtained dried solid electrolyte was measured using EIS without any applied pressure. The ionic conductivity was found to be 0.14 mS / cm at room temperature and 0.92 mS / cm at 100 °C.

[0255] Example 2: solid electrolyte free of ionic liquid

[0256] A mixture was prepared comprising:

[0257] 77.5 parts by weight of b is ( 3-tr iethoxy s il y Ip ropy I ) polyethylene oxide (SPEG)), with a molecular weight of approximately 1600 g / mol;

[0258] 5.5 parts by weight of l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lH,3H,5H)-trione (VPS);

[0259] 1.0 parts by weight of dibutyl phosphate;

[0260] 16 parts by weight of a LiTFSI solution; dissolved in acetonitrile as solvent, used in a 1 to 1 weight ratio compared to the SPEG.

[0261] The mixture was stirred for 3 minutes, blade coated, and left to polymerise for 1 hour at room temperature. The obtained polymer was dried at 100 °C for 2 hours under vacuum, to yield the dried solid electrolyte. A Flexible film was obtained with an area of at least 119 cm2, and a thickness of 48 pm, and can be seen in Figure 8. The water content of the film was less than 100 ppm.

[0262] The ionic conductivity of the dried solid electrolyte was measured using EIS without any applied pressure, and found to be 0.001 mS / cm at room temperature (20 °C). When measured at 100 °C, the ionic conductivity increased to 0.62 mS / cm.

[0263] Ionic conductivity performance

[0264] The ionic conductivity of the electrolyte films is characterised using EIS without any applied pressure. Each electrolyte film is sandwiched between a stainless-steel (SS) disk (d = 1.5 cm) to form a symmetric [SS / electrolyte / SS] cell. An alternating potential is 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 via electrical impedance spectroscopy (EIS) and converted to conductivity values.

[0265] Figure 1 shows the the ionic conductivity (mS / cm) for the different electrolyte films in function of the temperature. Figure 1 (a) shows the behaviour of the film comprising ionic liquid (Example 1), and Figure 1 (b) shows the behaviour of the film free of ionic liquid (Example 2). The profiles are depicted for two measurements: a first obtained by increasing the temperature ('uphill') and a second by decreasing the temperature ('downhill').

[0266] Both films exhibit reversible behavior when heating the solid electrolyte and then cooling it down. Notably, even the film free of ionic liquid (Example 2), shows a higher ionic conductivity at room temperature (1x10’5S / cm) compared to traditional PEO electrolyte (10'7to IO-8S / cm at RT, IO-5to 10sS / cm at 60 °C).

[0267] Figure 2 shows the ionic conductivity (mS / cm) profiles during the heating phase ('uphill') of the experiments conducted to produce Figure 1 for the films of Example 1 (comprising ionic liquid) and Example 2 (free of ionic liquid), demonstrating the influence of the ionic liquid on the results. Electrochemical stability window (ESW)

[0268] The ESW of a SUS | | Li electrochemical cell configuration assembled with a solid electrolyte film in a crimped coin cell was characterised using LVS. The applied scan rate used was 20 mV / s.

[0269] Figure 3 shows the current density (mA / cm2) as a function of the potential (V vs Li / Li+) for the film obtained in Example 1. The ESW was determined to be 4.9 V.

[0270] Thermal performance

[0271] The thermal degradation of the films is measured using TGA. The TGA profile included a heating rate of 5 °C / min up to 600 °C, run under Nitrogen gas. The thermal stability can be determined from the temperature at 5% weight loss or at 10% weight loss.

[0272] Figure 4 shows the TGA profiles for the solid electrolyte films of Example 1 and Example 2 in the temperature range of 25-600 °C. For the film of Example 1, the thermal stability was determined to be 221 °C at a 5% weight loss, while the residual at 600 °C was 9.5%. For the film of Example 2, the thermal stability was determined to be 292 °C at a 10% weight loss, while the residual at 600 °C was 20%. Flammability

[0273] The flammability of the films of Example 1, Example 2 and a control standard organic electrolyte, consisting of Ethylene Carbonate / Diethyl Carbonate (ED / DEC) containing IM LiPF6, was assessed by were exposure to an open flame.

[0274] Figure 5 illustrates the ignition times, revealing that the standard organic electrolyte readily ignites within 3 seconds, consistent with literature reports, while the film of Example 1 ignited after 12 seconds. Notably, the film of Example 2 did not ignite even after 197 seconds, prompting the discontinuation of the experiment. This test demonstrates the enhanced flame resistance of films produced using the solid electrolyte described herein. Self-extinguishing time

[0275] The self-extinguishing properties of the films of Example 1, Example 2 and a control standard organic electrolyte, consisting of ED / DEC containing IM LiPFg, were assessed following ignition.

[0276] Figure 6 illustrates the self-extinguishing times, with the control standard organic electrolyte taking 40 seconds to extinguish. Notably, the film of Example 1 extinguished after 15 seconds, while the film of Example 2 only took 10 seconds to self-extinguish. This test underscores the improved self-extinguishing properties and thus enhanced fire safety of films produced using the solid electrolyte described herein.

[0277] Example 3: A lithium battery pouch cell

[0278] A lithium battery pouch cell (Cell 1) was constructed by sandwiching the solid electrolyte film of Example 1, measuring 3.3 x 4.8 cm2with a thickness of 50 pm, between a Li metal anode (25 pm) and a porous LiFePCU (LFP) cathode impregnated withthe solid electrolyte within its pores. As a result of the coating step, the pores of the cathode were filled with the solid electrolyte and a 20 pm overfill was present on top of the cathode electrode. The cathode had an areal capacity of 1 mAh / cm2.

[0279] The solid electrolyte film functions as a separator between the Li anode and the LiFePO4cathode. The overfill ensures proper interfacial contact between the electrodes and the solid electrolyte, thereby facilitating ion transport and improving cell performance.

[0280] Electrochemical performances

[0281] The electrochemical performance of Cell 1 was evaluated by means of a formation test, during which several charge and discharge cycles were conducted, within a voltage window of 2.5 V to 3.8 V.

[0282] Figure 7 presents the voltage (V) vs. Li / Li+in function of the specific capacity (mAh / g), from which the full theoretical capacity (at low C-rate) can be determined as 150 mAh / g, with a Coulombic efficiency of 96%. These results demonstrate that the lithium battery pouch cell exhibits enhanced performance characteristics and is well-suited for the applications described herein. The functional cross-linked polymer is therefore suitable to work as solid electrolyte in lithium battery where it can work in a full cell using LFP and lithium metal.

[0283] Example 4: Impact of organo-tri-alkoxy silane comprising metal ion chelating moiety (M+) on ionic conductivity at room temperature

[0284] A series of solid electrolyte mixtures were prepared with varying amounts of an organo-trialkoxysilane compound comprising a metal ion (M+)-chelating moiety. The weight percentage of the silane compound was varied while keeping the other components constant. The ionic conductivity of each sample was measured at room temperature (20 °C) using EIS without applied pressure.

[0285] Figure 9 shows the the ionic conductivity (mS / cm) for the different samples as a function of the weight percentage of organo-tri-alkoxy silane in the mixture.

[0286] A clear ionic conductivity increase could be seen when increasing the amount of organo-tri-alkoxy silane in the mixture up to an optimum at approximately 5 wt.%. Beyond 5 wt.%., a slight decrease was noted, although still remaining higher than those typically reported for conventional PEO-based solid electrolytes (IO-7to 10'8S / cm at room temperature).

[0287] Example 5: Solid electrolyte with cross-linker and clay mineral particles

[0288] A mixture was prepared comprising:

[0289] 56.5 parts by weight of bis(3-triethoxysi ly I propyl) polyethylene oxide (SPEG), with a molecular weight of approximatelylGOO g / mol;

[0290] 5.5 parts by weight of l,3,5-tris[3-(trimethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lH,3H,5H)-trione (VPS);

[0291] 1.0 parts by weight of dibutyl phosphate;

[0292] 30.0 parts by weight of EMIFSI (ionic liquid )

[0293] 6 parts by weight of a LiTFSI;

[0294] 1.0 wt. of halloysite nanotubes (HNT); dissolved in acetonitrile as solvent, used in a 1 to 1 weight ratio compared to the SPEG.

[0295] The mixture was stirred for 3 minutes, blade coated, and left to polymerise for 1 hour at room temperature. The obtained polymer was dried at 100 °C for 2 hours under vacuum, to yield the dried solid electrolyte. A flexible film was obtained with an area of at least 119 cm2, and a thickness of 70 pm. The water content was less than 100 ppm.

[0296] The resulting solid electrolyte comprised 56.5 wt.% of SPEG, 1.0 wt.% of HNT, and 5.5 wt.% of VPS; with wt.% relative to the total weight of the solid electrolyte.

[0297] Example 6: Electrochemical energy storage device comprising a single unit cell

[0298] Formation of the electrochemical energy storage device

[0299] A Li battery pouch cell (Cell 2) was constructed by pressing a composite cathode (Lithium Nickel Manganese Cobalt Oxide LiNio.s no.2Coo.202(NMC62 ) cathode) comprising an active material loading of 1 mAh / cm2on a single-layer cathode footprint measuring 3 x 4.5 cm2(total area: 13.5 cm2) onto the formed solid electrolyte prepared in Example 5.

[0300] Then, a lithium metal electrode with a thickness of 26 pm was pressed onto the opposite side of the solid electrolyte by applying an external pressure of 25 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 enclosed between two pouch foils, each measuring 8 x 5 cm2, and the pouch foil was sealed using a vacuum sealing device to obtain the final pouch cell .

[0301] Electrochemical performances

[0302] The electrochemical characterization of the obtained Cell 2 was conducted in a cell test system at a controlled temperature of 45.0 + 0.5 °C. Testing was performed at different C-rates, including C / 10, C / 6, C / 3, 1C and 2C, for the formation cycle tests. Additionally, the cycle life of the Cell 2 was evaluated through continuous charge-discharge cycles within a voltage window of 3.0-4.2 V.

[0303] As shown in Figure 10 the discharge capacity of Cell 2 remained around 155 mAh / g for up to 30 cycles at the C / 10, C / 6, and C / 3 discharge rates.

[0304] From the data presented in Figure 10, it follows that the obtained electrochemical energy storage devices according to the present disclosure advantageously exhibit a high discharge-specific capacity and approximately 100% Coulombic efficiency.

Claims

CLAIMS1. A process for producing a solid electrolyte, comprising the steps of:- contacting, in the presence of a catalyst:- a polymer precursor compound comprising polyethylene glycol (PEG) and / or polytetrahydrofuran (PTHF), wherein the polymer precursor compound comprises, on average per polymer precursor molecule:- at least 2.0 alkoxysilyl functional groups, with a functionality of at least 2.0, preferably at least 2.5, preferably at least 3.0; and / or- at least 1.0 alkoxysilyl functional groups, with a functionality of at least 3.0;- a silane compound comprising an organo-tri-alkoxy silane, an organo-tetra- alkoxy silane, and / or a mixture thereof; the silane compound further comprising a metal ion (M+) chelating moiety selected from the group consisting of: a cyanurate, a crown ether, an aza-crown ether, a thia-crown ether, a cryptand, a carbamate, a cyano group, a thiocyanate group, and / or a metallacrown;- a metal (M+) salt, preferably selected from Li+, Na+, Mg+, Ca+, Al+, and / or any combination thereof, more preferably Li+;- a solvent, preferably an organic solvent; and,- optionally, an ionically conductive compound; thereby obtaining a solid electrolyte; and,- optionally, drying the obtained solid electrolyte.

2. The process according to claim 1, wherein the metal ion (M+) chelating moiety is a cyclic moiety or a macrocyclic moiety.

3. The process according to any one of the preceding claims, wherein the alkoxysilyl functional groups are functional end groups of the polymer precursor; and / or wherein the alkoxysilyl functional groups are tri-alkoxysilyl functional groups.

4. The process according to any one of the preceding claims, wherein the organo-tri-alkoxy silane or the organo-tetra-alkoxy silane, is a polyfunctional organo-tri-alkoxy silane or a polyfunctional orga no -tetra -alkoxy silane.

5. The process according to claim 4 wherein in the organo-tri-alkoxy silane or the organo-tetra- alkoxy silane, the one or more tri-alkoxy silane group or the one or more tetra-alkoxy silanes are side chains on the metal ion (l\ZI+) chelating moiety.

6. The process according to any one of the preceding claims, wherein the organo-tri-alkoxy silane or the organo-tetra-alkoxy silane 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 (VPS), l,3,5-tris[3- (triethoxysilyl)propyl]-l,3,5-triazine-2,4,6(lh,3h,5h)-trione, bis(3-triethoxysilylpropyl)amine, triethoxysilylpropyl ethylcarbamate, 3-thiocyanatopropyltriethoxysilane, 3- isocyanotopropyltrimethoxysilane, or mixtures thereof.

7. The process according to any one of the preceding claims, wherein the catalyst is a phosphoric acid organocatalyst.

8. The process according to claim 7, wherein the catalyst is selected from the group consisting of: a phosphoric acid diester, dibutyltin dilaurate, tetrabutyl titanate, zirconium propoxide, p- toluenesulfonic acid, triethylamine, imidazoles, or mixtures thereof.

9. The process according to any one of the preceding claims, wherein the solvent is an organic solvent, preferably a polar organic solvent, more preferably a polar aprotic solvent; and / or preferably, wherein the solvent is substantially free of water.

10. The process according to any one of the preceding claims, wherein the process is anhydrous such that substantially no water is added; and wherein the water content in the solid electrolyte, after the optional drying, is less than 100 ppm, preferably less than 50 ppm, more preferably less than 10 ppm.

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

12. The process according to any one of the preceding claims, wherein the ionically conductive compound comprises an ionic liquid, preferably is an ionic liquid.

13. The process according to any one of the preceding claims, wherein at least 70.0 to at most 100.0 parts by weight of the polymer precursor compound are contacted with:- at least 0.0 to at most 30.0 parts by weight of the organo-tri-alkoxy silane, the organo- tetra-alkoxy silane and / or the mixture thereof, preferably at least 1.0 to at most 25.0 parts by weight, more preferably at least 3.0 to at most 20.0 parts by weight, more preferably at least 5.0 to at most 15.0 parts by weight, more preferably still at least 10.0 to at most 12.0 parts by weight;- at least 0.0 to at most 50.0 parts by weight of the ionically conductive compound, preferably at least 2.0 to at most 45.0 parts by weight, more preferably still at least 5.0 to at most 40.0 parts by weight, more preferably still at least 10.0 to at most 30.0 parts by weight, more preferably still at least 15.0 to at most 25.0 parts by weight;- at least 3.0 to at most 20.0 part by weight of the metal salt, preferably 5.0 to 18.0 parts by weight, more preferably 7.0 to 15.0 parts by weight, more preferably still 10.0 to 12.0 parts by weight; and,- at least 10.0 to at most 50.0 part by weight of the solvent, preferably 15.0 to 45.0 parts by weight, more preferably 20.0 to 40.0 parts by weight, more preferably still 25.0 to 35.0 parts by weight.

14. A solid electrolyte, for use in an electrochemical energy storage device, obtained by a process according to any one of the preceding claims 1 to 13.

15. A solid electrolyte for an electrochemical energy storage device, comprising: a crosslinked polymer comprising polyethylene oxide (PEG) and / or polytetrahydrofuran (PTHF), the crosslinked polymer being covalently crosslinked via bridging moieties; metal (M+) ions, preferably Li+ions, Na+ions, Mg+ions, Ca+ions, Al+ions, and / or any combination thereof, more preferably Li+ions; and, optionally, an ionically conductive compound; wherein the bridging moieties comprise -Si-O-Si- bonds, preferably -Si-O-Si-R-Si-O-Si- bonds; wherein the crosslinked polymer comprises one or more metal ion (M+)-chelating moieties that are covalently bonded to, or covalently incorporated in, the crosslinked polymer; and, wherein the metal ion (M+) chelating moieties are selected from the group consisting of: a cyanurate, a crown ether, an aza-crown ether, a thia-crown ether, a cryptand, a carbamate, a cyano group, a thiocyanate group, and / or a metallacrown.

16. Use of the solid electrolyte according to claim 14 or 15, as an interelectrode material in an electrochemical energy storage device.

17. An electrode comprising an electrode active material and the solid electrolyte according to claim 14 or 15.

18. The electrode according to claim 17 wherein the solid electrolyte forms a covering and / or coating layer on the electrode active material, and / or wherein the electrode comprises a plurality of pores formed by the electrode active material, and the solid electrolyte fills at least a portion of the pores.

19. An electrochemical energy storage device, comprising a positive electrode, a negative electrode; and the solid electrolyte according to claim 14 or 15.

20. The electrochemical energy storage device according to claim 19, wherein the solid electrolyte forms a covering and / or coating layer on at least one of the electrodes, and / or wherein at least one electrode comprises a plurality of pores, and the solid electrolyte fills at least a portion of the pores.

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