Solid-state electrolyte layer and applications thereof

Abstract

This invention proposes a solid electrolyte layer and its application, comprising: a first electrolyte layer, the first electrolyte layer including a high-entropy sulfide electrolyte, the chemical formula of the high-entropy sulfide electrolyte being: Li 4±x‑y A y (M1 a M2 b M3 c )S 4-δ X δ Wherein, 0≤x≤1.5, 0≤y≤1.5, and y≤4±x; 0.4≤a≤0.8, 0.1≤b≤0.4, 0.1≤c≤0.3, a+b+c=1, 0≤δ≤1; A is selected from one or two of Na or K; M1 is selected from one or more of Ge, Sn, Si, P, As or B; M2 is selected from one or more of Sb, Nb, Ta, V, Mo, W, Ti, Zr, Hf or Re; M3 is selected from one or more of Al, Ga, In, Bi, Pb, Mg, Ca, Zn, Cd, Y, Sc, La, Ba, Sr, Ce or Sm; X is selected from one or more of O, Se or Te; a second electrolyte layer is disposed on one side surface of the first electrolyte layer, and the second electrolyte layer comprises a polymer and a covalent organic framework material. Through this invention, high flexibility, high mechanical strength, and excellent long-cycle stability can be achieved, thus improving the performance of all-solid-state batteries.

Description

Technical Field

[0001] This invention relates to the field of power battery technology, specifically to a solid electrolyte layer and its application. Background Technology

[0002] In recent years, with the development of high-energy-density lithium metal batteries, solid-state electrolytes have become key materials for replacing traditional liquid electrolytes due to their high safety, wide electrochemical window, and potential to suppress lithium dendrite growth. Currently, solid-state electrolytes mainly include three categories: oxides, sulfides, and polymers. Among them, oxide solid-state electrolytes possess high stability, a wide voltage window, and moderate ionic conductivity, but suffer from high interfacial impedance, difficult processing, and poor electrode compatibility. Sulfide solid-state electrolytes exhibit excellent room-temperature ionic conductivity, but suffer from poor mechanical flexibility, insufficient chemical stability to the lithium metal anode, and a tendency to react with lithium to form a high-resistivity interfacial layer. They are also prone to hydrolysis in air and are difficult to process. Polymer solid-state electrolytes possess good flexibility, film-forming properties, and interfacial contact, but generally have low room-temperature ionic conductivity, and their mechanical strength is insufficient to effectively block lithium dendrite penetration. Therefore, a single type of electrolyte cannot simultaneously meet the multiple requirements of high ionic conductivity, excellent mechanical properties, and good interfacial stability. Existing composite electrolytes are mostly homogeneous structures, lacking a synergistic functional partitioning design for the high oxidation environment on the positive electrode side and the strong reducing environment on the negative electrode side. Summary of the Invention

[0003] This invention proposes a solid electrolyte layer and its application. The solid electrolyte layer provided by this invention, which is composed of a double electrolyte layer, can achieve high flexibility, high mechanical strength and excellent long cycle stability, thereby improving the performance of all-solid-state batteries.

[0004] To solve the above-mentioned technical problems, the present invention provides a solid electrolyte layer, comprising:

[0005] A first electrolyte layer, comprising a high-entropy sulfide electrolyte, wherein the chemical formula of the high-entropy sulfide electrolyte is: Li 4±x-y A y (M1 a M2 b M3 c )S 4-δ X δWherein, 0≤x≤1.5, 0≤y≤1.5, and y≤4±x; 0.4≤a≤0.8, 0.1≤b≤0.4, 0.1≤c≤0.3, a+b+c=1, 0≤δ≤1; A is selected from one or two of Na or K; M1 is selected from one or more of Ge, Sn, Si, P, As or B; M2 is selected from one or more of Sb, Nb, Ta, V, Mo, W, Ti, Zr, Hf or Re; M3 is selected from one or more of Al, Ga, In, Bi, Pb, Mg, Ca, Zn, Cd, Y, Sc, La, Ba, Sr, Ce or Sm; X is selected from one or more of O, Se or Te. A second electrolyte layer is disposed on one side surface of the first electrolyte layer, and the second electrolyte layer comprises a polymer and a covalent organic framework material.

[0006] In one embodiment of the present invention, the thickness of the first electrolyte layer is 1 μm to 200 μm; and / or, the thickness of the second electrolyte layer is 1 μm to 100 μm.

[0007] In one embodiment of the present invention, the thickness of the first electrolyte layer is 30 μm to 50 μm; and / or, the thickness of the second electrolyte layer is 10 μm to 40 μm.

[0008] In one embodiment of the present invention, the conductivity of the first electrolyte layer is 1×10⁻⁶. -3 S / cm to 2×10 -2 S / cm; and / or, the conductivity of the second electrolyte layer is 1×10⁻⁶. -5 S / cm to 1×10 -3 S / cm.

[0009] In one embodiment of the present invention, the framework of the covalent organic framework material contains at least one heteroatom selected from nitrogen, oxygen, fluorine, or sulfur; the framework is formed by at least one covalent linking group selected from imine bond, hydrazone bond, β-ketoenamine bond, borate ester bond, triazine ring, benzoxazole, benzothiazole, imide bond, or urea bond.

[0010] In one embodiment of the present invention, the covalent organic framework material has a two-dimensional or three-dimensional periodic topological structure, and the covalent organic framework material has a periodic nanopore structure; and / or, the pore size of the covalent organic framework material is 1 nm to 3 nm, and the specific surface area of ​​the covalent organic framework material is greater than or equal to 500 m². 2 / g.

[0011] In one embodiment of the present invention, the covalent organic framework material is nanoparticles or nanosheets; the median particle size of the nanoparticles is 50 nm to 5 μm; the sheet diameter of the nanosheets is 50 nm to 5 μm and the thickness is 2 nm to 100 nm.

[0012] In one embodiment of the present invention, the second electrolyte layer further includes a lithium salt, wherein the lithium salt is selected from at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium bisfluorosulfonylimide, lithium hexafluorophosphate, or lithium dioxolaneborate.

[0013] In one embodiment of the present invention, the polymer comprises fluorinated polyimide, and / or the mass ratio of the polymer, the covalent organic framework material and the lithium salt is (35 to 98):(1 to 50):(1 to 15).

[0014] The present invention also provides an all-solid-state battery, comprising: Positive electrode sheet; Negative electrode sheet; and A solid electrolyte layer is disposed between the positive electrode and the negative electrode, and is selected from the solid electrolyte layer described above, wherein the first electrolyte layer of the solid electrolyte layer is located on the side closer to the positive electrode.

[0015] In summary, this invention proposes a solid electrolyte layer and its application. The high-entropy sulfide electrolyte in the first electrolyte layer effectively suppresses grain boundary migration and phase transition through a multi-principal solid solution structure, improving interfacial chemical stability and mechanical flexibility, and reducing Young's modulus to achieve "flexible wetting" with the positive electrode active material, thereby maintaining a stable ion pathway under a low stacking pressure of 1 MPa. The first electrolyte layer combines high oxidation stability, low Young's modulus, and high ionic conductivity, enabling good wetting with the positive electrode active material through a flexible transition in all-solid-state batteries, maintaining a good ion pathway without high pressure. The polymer in the second electrolyte layer has excellent flexibility and viscoelasticity, allowing it to tightly adhere to the surface of the negative electrode sheet under conditions not exceeding 1 MPa, filling microscopic voids and achieving excellent interfacial compatibility on the negative electrode side. The polymer and COFs synergistically interact on the lithium metal surface, generating a uniform and dense LiF / Li3N composite solid electrolyte interfacial film in situ, which can significantly reduce interfacial impedance and suppress side reactions and dendrite growth. Furthermore, the LiF / Li3N interface layer induced by COFs possesses self-healing properties, which can further reduce interfacial contact resistance. The solid electrolyte layer, with its two sides exhibiting different properties, achieves a balance of high flexibility, high mechanical strength, and excellent long-cycle stability, thereby enhancing the performance of the all-solid-state battery. Detailed Implementation

[0016] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0017] It should be understood that the invention can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0018] The technical solution of the present invention will be further described in detail below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This invention proposes a solid electrolyte layer, comprising a first electrolyte layer and a second electrolyte layer stacked sequentially, with the second electrolyte layer disposed on one side surface of the first electrolyte layer. The first electrolyte layer comprises a high-entropy sulfide electrolyte with the chemical formula: Li. 4±x-y A y (M1 a M2 b M3 c )S 4-δ X δ Wherein, 0≤x≤1.5, 0≤y≤1.5, and y≤4±x; 0.4≤a≤0.8, 0.1≤b≤0.4, 0.1≤c≤0.3, a+b+c=1, 0≤δ≤1; A is selected from any one or two of Na or K; M1 is selected from any one or more of Ge, Sn, Si, P, As or B; M2 is selected from any one or more of Sb, Nb, Ta, V, Mo, W, Ti, Zr, Hf or Re; M3 is selected from any one or more of Al, Ga, In, Bi, Pb, Mg, Ca, Zn, Cd, Y, Sc, La, Ba, Sr, Ce or Sm; X is selected from any one or more of O, Se or Te. The second electrolyte layer includes polymers and covalent organic frameworks (COFs). By forming a solid electrolyte layer with two electrolyte layers, the two sides of the solid electrolyte layer have different properties, which can take into account high flexibility, high mechanical strength and excellent long cycle stability as a whole, thereby improving the performance of all-solid-state batteries.

[0020] In one embodiment of the present invention, the first electrolyte layer further includes a first adhesive, such as selected from polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), polymerized styrene-butadiene rubber (SBR), polyvinylpyrrolidone (PVP), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), polyacrylic acid (PAA), polyurethane (PU), polyvinyl alcohol (PVA), sodium alginate (Alg), ethylene-propylene-diene monomer (EPDM), fluororubber, and β-cyclodextrin polymer. Polymer (β-CDp), polypropylene emulsion (LA132), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), fluorinated ethylene-propylene copolymer (FEP), perfluoroalkoxy alkane (PFA), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyvinylidene fluoride-chlorotrifluoroethylene copolymer (PVDF-CTFE), and one or more of the following:

[0021] In one embodiment of the present invention, in the first electrolyte layer, the mass ratio of the high-entropy sulfide electrolyte to the first binder is, for example, (95 to 99.5):(0.5 to 5), and the thickness of the first electrolyte layer is, for example, 1 μm to 200 μm, or more specifically, 30 μm to 50 μm, and the conductivity of the first electrolyte layer is, for example, 1 × 10⁻⁶. -3 S / cm to 2×10 -2S / cm. High-entropy sulfide electrolytes effectively suppress grain boundary migration and phase transitions through their multi-principal solid solution structure, enhancing interfacial chemical stability and mechanical flexibility. They also reduce Young's modulus to achieve "flexible wetting" with the cathode active material, thus maintaining a stable ion pathway under low stacking pressure. Furthermore, the high configurational entropy and lattice distortion effect brought about by the multi-principal structure of the high-entropy sulfide electrolyte significantly improves the material's configurational entropy and disorder, lowering the energy barrier for lithium-ion diffusion and thus improving the ionic conductivity of the sulfide electrolyte. Simultaneously, the introduction of element X enhances the air stability of the sulfide electrolyte, exhibiting excellent chemical / electrochemical stability and a unique self-healing tendency. By forming a first electrolyte layer with a high content of high-entropy sulfide electrolyte, which possesses high oxidation stability, low Young's modulus, and high ionic conductivity, good wetting with the cathode active material can be achieved through a flexible transition in all-solid-state batteries, maintaining a good ion pathway without high pressure. By controlling the thickness of the first electrolyte layer, the conductivity of the first electrolyte layer is ensured, while its mechanical strength is also controlled. After assembly under a 1MPa stacking pressure, the initial interface impedance is less than 1.5Ω and remains stable during cycling.

[0022] In one embodiment of the present invention, the above-mentioned high-entropy sulfide electrolyte can be prepared by the following method: First, according to the chemical formula Li 4±x-y A y (M1 a M2 b M3 c S4 δ X δ The Li source, A source, M1 source, M2 source, M3 source, S source, and X source are mixed uniformly according to a stoichiometric ratio, and then added to a ball mill jar for ball milling to obtain precursor powder. The precursor powder is then sintered and cooled to obtain a high-entropy sulfide electrolyte. In a specific embodiment of the present invention, the Li source is, for example, derived from lithium sulfide or LiX, the A source is derived from the corresponding element's sulfide, the X source is derived from LiX, the M1, M2, and M3 sources are, for example, derived from the corresponding element's sulfide, and the S source is derived from lithium sulfide, the A source's sulfide, or the M source's sulfide, or may be derived from other substances. The ball-to-material mass ratio in the ball mill jar is, for example, 1:1 to 100:1, the ball milling time is, for example, 1 hour to 48 hours, and the ball milling speed is, for example, 50 rpm to 1500 rpm. The precursor powder obtained by ball milling is then sintered at a temperature of 150°C to 500°C for 1 to 12 hours, and then cooled at a rate of 1°C / s to 10°C / s to obtain a high-entropy sulfide electrolyte. All the above steps are carried out in an inert atmosphere such as argon during the preparation of the high-entropy sulfide electrolyte.

[0023] The preparation method of high-entropy sulfide electrolytes is not limited to this; other conventional methods for preparing sulfide electrolytes can also be used.

[0024] In one embodiment of the present invention, the second electrolyte layer comprises a polymer and a covalent organic framework material, wherein the polymer includes, for example, fluorinated polyimide, and the fluorinated polyimide is prepared, for example, by a polycondensation reaction of a fluorinated aromatic dianhydride and an aromatic diamine, wherein the molar ratio of the fluorinated aromatic dianhydride to the aromatic diamine is, for example, 1:0.95 to 1:1.05. In a specific embodiment of the present invention, the fluorinated aromatic dianhydride monomer includes, for example, at least one selected from 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA), 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, or 1,3-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride. Fluorinated aromatic diamine monomers include, for example, at least one of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB), 4,4'-bis(4-aminophenoxy)octafluorobiphenyl (8F-APB), or 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether (6F-ODA). The polymer exhibits excellent flexibility and viscoelasticity, allowing it to tightly adhere to the surface of the negative electrode sheet under pressure not exceeding 1 MPa, filling microscopic voids and achieving excellent interfacial compatibility on the negative electrode side.

[0025] In one embodiment of the present invention, the covalent organic framework material is a crystalline porous polymer material formed by organic monomers linked by covalent bonds. In this embodiment, the framework of the covalent organic framework material contains at least one heteroatom selected from nitrogen, oxygen, fluorine, or sulfur. In the second electrolyte layer, the fluorine element in the fluorinated polyimide and the nitrogen, oxygen, and other functional groups in the COFs framework work synergistically on the lithium metal surface to generate a uniform and dense LiF / Li3N composite solid electrolyte interface (SEI) in situ, which can significantly reduce interfacial impedance and suppress side reactions and dendrite growth. Furthermore, the LiF / Li3N interface layer induced by COFs has self-healing properties, which can further reduce interfacial contact resistance.

[0026] In one embodiment of the present invention, the skeleton of COFs is formed, for example, by at least one covalent linking group selected from imine bonds, hydrazone bonds, β-ketoenamine bonds, borate ester bonds, triazine rings, benzoxazole, benzothiazole, imide bonds, or urea bonds, or, for example, selected from one or more of imine bonds, β-ketoenamine bonds, triazine rings, benzothiazole, or benzoxazole. This is because some COFs linkages may undergo hydrolysis, sulfidation, or redox side reactions when in prolonged contact with high-entropy sulfide electrolytes. For example, borate ester bonds are easily hydrolyzed in the presence of trace amounts of moisture to generate B(OH)3 and release H2S; urea bonds may decompose at the reducing lithium metal / sulfide interface to generate NH3. Therefore, imine bonds, β-ketoenamine bonds, triazine rings, benzothiazoles, and benzoxazoles possess higher chemical inertness and thermodynamic stability. Imine bonds and β-ketoenamine bonds have conjugated structures, strong electron delocalization, and excellent resistance to reduction. Triazine rings are electron-deficient aromatic heterocycles, resistant to reduction, and do not contain easily broken BO or NH bonds. Benzothiazoles / benzoxazoles are fused heterocycles with high structural rigidity, in which sulfur, nitrogen, and oxygen atoms (S, N, O) are embedded in the aromatic system, making them less susceptible to oxidation. 2- The reaction occurs, which helps to reduce interfacial impedance.

[0027] In one embodiment of the present invention, the COFs have a two-dimensional or three-dimensional periodic topological structure and a periodic nanopore structure. In this embodiment, the pore size of the COFs is, for example, 1 nm to 3 nm, and the specific surface area of ​​the COFs is, for example, greater than or equal to 500 m². 2 / g. The ordered channels of COFs can provide continuous lithium ions (Li). + The transmission channel can improve the conductivity of the second electrolyte layer. In one embodiment of the present invention, the conductivity of the second electrolyte layer is, for example, 1 × 10⁻⁶. -5 S / cm to 1×10 -3 S / cm.

[0028] In one embodiment of the present invention, COFs are, for example, at least one of nanoparticles or nanosheets. When the COFs are nanoparticles, the median particle size D50 of the nanoparticles is, for example, 50 nm to 5 μm. The median particle size D50 refers to the particle size corresponding to a cumulative distribution percentage of 50% in the particle size distribution of a volume-based particle group; that is, half of the particles in the sample have a particle size less than or equal to this value, and the other half have a particle size greater than or equal to this value. When the COFs are nanosheets, the sheet diameter is, for example, 50 nm to 5 μm, and the thickness of the nanosheet is, for example, 2 nm to 100 nm. By controlling the size of the COFs, it is possible to ensure that the COFs are uniformly distributed in the second electrolyte layer and reduce the aggregation of COFs.

[0029] In one embodiment of the present invention, the second electrolyte layer further includes, for example, a lithium salt selected from at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bisfluorosulfonylimide (LiFSI), lithium hexafluorophosphate (LiPF6), or lithium dioxolane borate (LiBOB). In one embodiment of the present invention, in the second polymer layer, the mass ratio of the polymer, the covalent organic framework material, and the lithium salt is, for example, (35 to 98):(1 to 50):(1 to 15), or, for example, (55 to 89):(10 to 30):(1 to 15), or, for example, (60 to 84):(15 to 25):(1 to 15). By adding a lithium salt to the second electrolyte layer and controlling the content of each substance in the second electrolyte layer, the ionic conductivity of the second electrolyte layer is improved, the interfacial stability is regulated, and the mechanical and thermal stability is optimized.

[0030] In one embodiment of the present invention, the thickness of the second electrolyte layer is, for example, 1 μm to 100 μm, or, for example, 10 μm to 40 μm. By controlling the composition and thickness of the second electrolyte layer, excellent interfacial compatibility can be achieved on the negative electrode side, and a uniform and stable LiF / Li3N composite protective layer can be constructed in situ, effectively suppressing lithium dendrite growth. Through the double-layer solid electrolyte layer, high flexibility, high mechanical strength, and excellent long-cycle stability are achieved, providing key material support for the practical application of high energy density and high safety all-solid-state batteries.

[0031] In one embodiment of the present invention, the above-mentioned COFs can be prepared by the following method: dispersing the first monomer and the second monomer in an organic solvent in a stoichiometric ratio to obtain a mixed raw material; adding acetic acid to the mixed raw material, degassing by ultrasonication or stirring, sealing it in a polytetrafluoroethylene-lined reactor, and reacting at a constant temperature of, for example, 100°C to 150°C for 24 h to 72 h to obtain an intermediate product; cooling the intermediate product, centrifuging, washing, and drying it, and then activating it under vacuum conditions of 80°C to 120°C for 12 h to 24 h to obtain COFs powder material.

[0032] In one embodiment of the present invention, the molar ratio of the first monomer to the second monomer is, for example, 1:0.9 to 1.2. The first monomer and the second monomer are each selected from one or more of the following: ammonia monomers, aldehyde monomers, ketone-aldehyde monomers, acylhydrazine monomers, boric acid monomers, vicinal diol monomers, nitrile monomers, dianhydride monomers, or isocyanate monomers. The ammonia monomers include, for example, at least one of 1,3,5-tris(4-aminophenyl)benzene, 1,4-phenylenediamine, 1,3-phenylenediamine, 2-fluoro-1,4-phenylenediamine, 3,5-difluoro-1,2-phenylenediamine, 4,4'-thiodiphenylamine, 2-aminobenzenethiophenol, 2-amino-4-fluorophenol, or 2-amino-5-fluorophenol. Aldehyde monomers include, for example, at least one of terephthalaldehyde, isophthalaldehyde, 2,5-difluoroterephthalaldehyde, tetrafluoroterephthalaldehyde, 4,4'-thiodibenzoaldehyde, 2,5-thiophene dicarboxaldehyde, or 2,5-dimethoxyterephthalaldehyde. Ketone aldehyde monomers include, for example, at least one of 1,3,5-tricarboxymethyl phloroglucinol, 2-fluoro-1,3,5-tricarboxymethyl phloroglucinol, or 2-thio-1,3,5-tricarboxymethyl phloroglucinol. Acylhydrazine monomers include, for example, at least one of terephthaloyl hydrazine, 1,3,5-tris(4-acylhydrazine phenyl)benzene, 2-fluoroterephthaloyl hydrazine, or sulfur-containing acylhydrazine derivatives, and sulfur-containing acylhydrazine derivatives include, for example, at least one of 4,4'-dithiodibenzoyl hydrazine, lipoyl hydrazine, or diphenyl sulfide-type diacylhydrazine. Boric acid monomers include, for example, at least one of 1,4-phenylenediboronic acid, tripinal ester of 1,3,5-phenyltriboronic acid, 2-fluoro-1,4-phenylenediboronic acid, or sulfur-containing boric acid derivatives; sulfur-containing boric acid derivatives include, for example, at least one of dibenzothiophene-4-boronic acid, dibenzothiophene-4-boronic acid, or thiophene-3-boronic acid. Ortho-diol monomers include, for example, at least one of 2,3,6,7,10,11-hexahydroxytriphenyl, tetrafluorocatechol, or thiocatechol. Nitrile monomers include, for example, at least one of terephthalonitrile, 1,3,5-tricyanobenzene, 2-fluoroterephthalonitrile, tetrafluoroterephthalonitrile, 2-thioterephthalonitrile, or thiophenedicarbonyl. Dihydride monomers include, for example, at least one of pyromellitic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, or 4,4'-(hexafluoroisopropylidene)diphthalic anhydride. Isocyanate monomers include, for example, at least one of terephthalic diisocyanate or fluorinated aromatic isocyanate.

[0033] In one embodiment of the present invention, the organic solvent is, for example, at least one selected from o-dichlorobenzene, n-butanol, mesitylene, or 1,4-dioxane. In another embodiment, the organic solvent is, for example, a 1:1 volume ratio mixture of o-dichlorobenzene and n-butanol, or a 1:1 volume ratio mixture of mesitylene and 1,4-dioxane. The content of the first monomer and the second monomer in the organic solvent is, for example, 1 wt% to 10 wt%. Acetic acid is, for example, a 3 mol / L to 6 mol / L aqueous solution of acetic acid, and the amount of acetic acid added is, for example, 5% to 20% of the volume of the organic solvent.

[0034] In one specific embodiment of the present invention, to obtain nanoparticle-shaped COFs, a monofunctional modulator is added to the mixed raw materials. The monofunctional modulator is, for example, at least one of aniline or acetic acid, and the molar ratio of the monofunctional modulator to the total monomer is, for example, 10:1 to 100:1. The end-capping effect of the monofunctional modulator restricts the growth of crystals in three dimensions, thereby obtaining nanoparticles. To obtain nanosheet-shaped COFs, the COFs are subjected to liquid-phase ultrasonic exfoliation to obtain nanosheets, wherein the ultrasonic power is, for example, 300W to 800W, and the ultrasonic time is, for example, 2h to 10h.

[0035] The preparation method of COFs is not limited to this. Other conventional methods for preparing COFs can also be used, or commercially available products can be purchased directly.

[0036] Based on the aforementioned solid electrolyte layer, this invention also proposes a method for preparing a solid electrolyte layer, comprising at least: adding a high-entropy sulfide electrolyte and a first binder to a first solvent in a mass ratio and mixing them uniformly to obtain a first slurry; coating the first slurry onto a substrate and drying it to obtain a first electrolyte layer; dispersing COFs in a second solvent to obtain a COFs dispersion; adding a fluorinated aromatic dianhydride and an aromatic diamine monomer to the COFs dispersion in a stoichiometric ratio and performing a polymerization reaction to form a polyamic acid / COFs mixed solution; adding a lithium salt to the mixed solution and stirring uniformly to obtain a second slurry; casting the slurry into a film and subjecting it to gradient thermal imidization treatment to obtain a second electrolyte layer; transferring the first electrolyte layer onto the second electrolyte layer by cold pressing or hot pressing, and peeling off the substrate to obtain a solid electrolyte layer.

[0037] In one embodiment of the present invention, the high-entropy sulfide electrolyte and the first binder are added according to the mass ratio of the first electrolyte layer. The first solvent is selected from one or more of the following: toluene, chlorobenzene, xylene, dimethyl carbonate, N-methylformamide, n-hexane, dimethyl glycol ether, dibutyl ether, ethanol, 1,2-ethylenediamine, 1,2-ethylenedithiol, acetonitrile, tetrahydrofuran, methanol, isopropyl ether, acetone, hexene, ethyl acetate, benzyl acetate, butyl butyrate, or diisobutyl ketone. The solid content in the first slurry is, for example, 40% to 60%. The substrate is selected from at least one of the following: polyethylene terephthalate (PET) film, aluminum foil, steel foil, or copper foil, to facilitate substrate removal in subsequent processes. After the first slurry is coated onto the substrate, it is vacuum dried at 60°C to 100°C for 6 hours to 24 hours.

[0038] In one embodiment of the present invention, the second solvent is selected from one or more polar aprotic solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), or dimethyl sulfoxide (DMSO). In the COFs dispersion, the concentration of COFs is, for example, from 0.1 mg / mL to 50 mg / mL, and the molar ratio of the fluorinated aromatic dianhydride to the aromatic diamine monomer is, for example, from 1:0.95 to 1:1.05.

[0039] In one embodiment of the present invention, the gradient thermal imidization treatment includes: heating the cast wet film from room temperature to a final temperature through at least two temperature stages under an inert atmosphere or vacuum. The final temperature is, for example, 150°C to 220°C, and the total treatment time is, for example, 2 hours to 6 hours. In a specific embodiment of the present invention, the gradient thermal imidization treatment includes heating from room temperature to a first temperature and holding at that temperature for a first time, heating from the first temperature to a second temperature and holding at that temperature for a second time, heating from the second temperature to the final temperature and holding at that temperature for a third time. The first temperature is, for example, 60 to 90°C, and the first time is, for example, 0.5 hours to 1 hour. Alternatively, the first temperature may be, for example, 100 to 140°C, and the first time may be, for example, 0.5 hours to 1 hour; the third time may be, for example, 1 hour to 2 hours. Through gradient thermal imidization treatment, the molecular structure uniformity and residual stress distribution of the second electrolyte layer can be significantly optimized, thereby improving its dimensional stability and mechanical properties.

[0040] This invention also proposes an all-solid-state battery, comprising a positive electrode, a negative electrode, and a solid electrolyte layer. The solid electrolyte layer is disposed between the positive and negative electrode layers. The solid electrolyte layer is selected from the aforementioned solid electrolyte layers, with a first electrolyte layer closer to the positive electrode and a second electrolyte layer closer to the negative electrode. In this invention, the all-solid-state battery can be, for example, a primary battery or a secondary battery. A secondary battery can be, for example, a pouch battery, a prismatic battery, or a cylindrical battery. This invention does not impose specific limitations on the type or category of all-solid-state batteries.

[0041] In one embodiment of the present invention, the positive electrode sheet includes a positive current collector and a positive active layer coated on at least one surface of the positive current collector. The positive current collector is, for example, a foil formed by surface treatment of materials such as nickel, titanium, aluminum, silver, stainless steel, or carbon. Besides foil, the positive current collector can also be used in any one or more combinations of various forms such as film, mesh, porous, foam, or nonwoven fabric.

[0042] In one embodiment of the present invention, the positive electrode active layer includes a positive electrode active material, the aforementioned high-entropy sulfide electrolyte, a positive electrode conductive agent, and a positive electrode binder. The positive electrode active material includes, for example, at least one of lithium nickel cobalt manganese oxide (NCM), lithium nickel oxide (LNO), lithium manganese oxide (LMO), lithium nickel manganese oxide (LNMO), lithium cobalt oxide (LCO), or lithium nickel cobalt aluminum oxide (NCA). The positive electrode conductive agent is selected from at least one of conductive carbon black, acetylene black, carbon fiber (VGCF), carbon nanotubes (CNT), or graphene. The positive electrode binder is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, hydrogenated nitrile rubber (HNBR), poly(ethylene oxide) (PEO), polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyethylene ether, polymethyl methacrylate (PMMA), ethylene-propylene-diene terpolymer (EPDM), or polyhexanefluoropropylene (Polyhexafluoropropylene). The mass ratio of the positive electrode active material, high-entropy sulfide electrolyte, positive electrode conductive agent, and positive electrode binder is, for example, (60 to 94):(5 to 30):(1 to 5):(1 to 5).

[0043] In a specific embodiment of the present invention, the positive electrode active material is selected as LiNi. 0.8 Co 0.1 Mn 0.1For O₂, carbon fiber is selected as the positive electrode conductive agent, and hydrogenated nitrile rubber is selected as the positive electrode binder. After fully stirring and mixing the positive electrode active material, high-entropy sulfide electrolyte, positive electrode conductive agent, and positive electrode binder, for example, in a mass ratio of 70:25:2:3 in xylene solvent to obtain a uniform positive electrode paste, it is coated on aluminum foil, dried, and cold-pressed to obtain the positive electrode sheet.

[0044] In an embodiment of the present invention, the negative electrode sheet, for example, includes a negative electrode current collector and at least a negative electrode active layer coated on one side surface of the negative electrode current collector. Among them, the negative electrode current collector is, for example, a copper foil current collector, a composite copper foil current collector, a carbon current collector, a foam copper current collector, or a stainless steel current collector, etc. The negative electrode active layer includes a negative electrode active material, the above-mentioned high-entropy sulfide electrolyte, a negative electrode conductive agent, and a negative electrode binder, etc. Among them, the negative electrode active material is selected from graphite-based materials, silicon materials, or composite materials composed of a combination of the two. Among them, the graphite-based materials include at least one of natural graphite or artificial graphite. Natural graphite includes at least one of massive graphite, flake graphite, or earthy graphite, etc. Artificial graphite includes at least one of single crystal graphite, polycrystalline graphite, pyrolytic graphite, or graphite fiber, etc. The silicon materials include, but are not limited to, silicon, silicon-carbon composite materials, and silicon oxides (SiO x , 0 < x < 2). The negative electrode conductive agent is, for example, selected from at least one of conductive carbon black, acetylene black, Ketjen black, carbon nanotubes, or graphene, etc. The negative electrode binder is, for example, selected from at least one of polypropylene, polyacrylate, polyethylene ether, polymethyl methacrylate, polyhexafluoropropylene, or styrene-butadiene rubber, etc. The negative electrode active layer can be prepared by dry or wet methods, and this application does not make specific restrictions.

[0045] In a specific embodiment of the present invention, the negative electrode active material is a graphite and silicon-carbon composite material with a mass ratio of 1:1, the negative electrode conductive agent is acetylene black, and the negative electrode binder is styrene-butadiene rubber. After fully stirring and mixing the negative electrode active material, high-entropy sulfide electrolyte, negative electrode conductive agent, and negative electrode binder, for example, in a mass ratio of 70:25:2:3 in xylene solvent to obtain a uniform negative electrode paste, it is coated on copper foil, dried, and cold-pressed to obtain the negative electrode sheet.

[0046] In an embodiment of the present invention, when obtaining a all-solid-state battery, the positive electrode sheet and the negative electrode sheet are respectively placed on both sides of the solid electrolyte layer. The positive electrode sheet is close to the first electrolyte layer, and the negative electrode sheet is close to the second electrolyte layer. After assembling and sealing, it is isopressurized and pressed at 500 MPa to obtain a all-solid-state battery. Among them, the assembly process of the all-solid-state battery is completed in an inert atmosphere.

[0047] Hereinafter, the present invention will be more specifically explained by citing examples, and these examples should not be construed as restrictive. Within the scope consistent with the gist of the present invention, appropriate modifications can be made, and they all fall within the technical scope of the present invention.

[0048] Example 1 Preparation of high-entropy sulfide electrolyte: Under an argon atmosphere, 1.835 mol of Li₂S, 0.06 mol of SnS₂, 0.21 mol of SiS₂, 0.165 mol of P₂S₅, 0.1 mol of Sb₂S₅, and 0.1 mol of Al₂S₃ were placed in a ball mill jar. Ball milling beads were added at a ball-to-material mass ratio of 30:1. The mixture was ball-milled at 100 rpm for 10 min, followed by further ball milling at 600 rpm for 16 h to obtain a homogeneous precursor powder. The precursor powder was then placed in a crucible and sintered at 200 °C for 20 h. After cooling at a rate of 5 °C / s, Li₂S₅ was obtained. 3.67 (Sn 0.1 Si 0.35 P 0.55 ) 0.6 Sb 0.2 Al 0.2 S4 electrolyte material, and Li with a median particle size D50 of 1 μm was obtained by sieving. 3.67 (Sn 0.1 Si 0.35 P 0.55 ) 0.6 Sb 0.2 Al 0.2 S4 electrolyte material.

[0049] Preparation of solid electrolyte layer: The above Li 3.67 (Sn 0.1 Si 0.35 P 0.55 ) 0.6 Sb 0.2 Al 0.2 S4 and PVDF are mixed at a mass ratio of 97:3, and xylene solvent is added to mix them to obtain a first slurry. The first slurry is coated on aluminum foil and dried under vacuum at 80°C for 12 hours to obtain a first electrolyte layer with a thickness of 45 μm.

[0050] Preparation of β-ketoenamine COFs: 1,3,5-tris(4-aminophenyl)benzene was selected as the first monomer and 1,3,5-tricarboxymethyl phloroglucinol was selected as the second monomer. They were dispersed in a 1:1 molar ratio in a mixed organic solvent of mesitylene and 1,4-dioxane in a 1:1 volume ratio. The total mass concentration of the first and second monomers in the organic solvent was controlled to be 5 wt%. A 3 mol / L acetic acid aqueous solution was added, accounting for 5% of the volume of the organic solvent. After ultrasonic degassing for 10 minutes, the mixture was sealed in a polytetrafluoroethylene-lined reactor and reacted at 120°C for 48 hours. After cooling, the solid was collected by centrifugation and washed three times with acetone and tetrahydrofuran in sequence. After drying, it was activated under vacuum at 100°C for 12 hours to obtain the β-ketoenamine COF powder particles with a particle size of approximately 500 nm.

[0051] The above-mentioned β-ketoenamine COF particles were dispersed in NMP solvent to obtain a COF dispersion with a concentration of 10 mg / mL. 6FDA and TFDB were added to the COF dispersion at a molar ratio of 1:1 to carry out a polymerization reaction, forming a polyamic acid / COF mixed solution. LiTFSI was then added and stirred until homogeneous to obtain a second slurry. The second slurry, based on a total solute mass of 100%, contained 20 wt% COFs and 6.5 wt% LiTFSI.

[0052] Under an inert atmosphere, the second slurry was cast into a film and subjected to gradient thermal imidization treatment at 80℃ for 30 min, 120℃ for 40 min, and 160℃ for 90 min to obtain a second electrolyte layer with a thickness of 20 μm. The first electrolyte layer was transferred onto the second electrolyte layer by cold pressing, and the aluminum foil was peeled off to obtain a solid electrolyte layer.

[0053] Preparation of positive electrode: LiNi 0.8 Co 0.1 Mn 0.1 O2, Li 3.67 (Sn 0.1 Si 0.35 P 0.55 ) 0.6 Sb 0.2 Al 0.2 S4, carbon fiber, and hydrogenated nitrile rubber were thoroughly mixed in xylene solvent at a mass ratio of 70:25:2:3 to obtain a positive electrode slurry. This slurry was coated onto aluminum foil, dried, and cold-pressed to obtain the positive electrode sheet. The areal capacity of the positive electrode sheet was 4 mAh / cm². 2 And cut it into round pieces with a diameter of 10mm.

[0054] Negative electrode: The negative electrode active material is a graphite and silicon-carbon composite material with a mass ratio of 1:1. The negative electrode active material and Li... 3.67 (Sn 0.1 Si 0.35 P 0.55 ) 0.6 Sb 0.2 Al 0.2 S4, acetylene black, and styrene-butadiene rubber were thoroughly mixed in xylene solvent at a mass ratio of 70:25:2:3 to obtain a negative electrode slurry. This slurry was coated onto copper foil, dried, and cold-pressed to obtain the negative electrode sheet. The areal capacity of the negative electrode sheet was 4.4 mAh / cm². 2 And cut it into round pieces with a diameter of 10mm.

[0055] Assembly of all-solid-state battery: Under an argon atmosphere, the above-mentioned positive electrode and negative electrode are placed on both sides of the solid electrolyte layer, with the positive electrode close to the first electrolyte layer and the negative electrode close to the second electrolyte layer. After assembly, the battery is sealed and pressed under isobaric pressure at 500 MPa to obtain an all-solid-state battery.

[0056] Example 2 In the preparation of high-entropy sulfide electrolytes, the raw materials were 1.95 mol Li₂S, 0.6 mol SiS₂, 0.05 mol Sb₂S₅, 0.04 mol MoS₃, 0.06 mol WS₃, and 0.1 mol Al₂S₃, yielding Li₂S electrolytes with a median particle size D50 of 1 μm. 3.9 Si 0.6 (Sb 0.5 Mo 0.2 W 0.3 ) 0.2 Al 0.2 S4 electrolyte material. The Li obtained in this embodiment was used in the preparation of the positive and negative electrode sheets. 3.9 Si 0.6 (Sb 0.5 Mo 0.2 W 0.3 ) 0.2 Al 0.2 The preparation steps for the S4 electrolyte material and other batteries are the same as in Example 1.

[0057] Example 3 In the preparation of high-entropy sulfide electrolytes, the raw materials were 2.02 mol Li₂S, 0.6 mol SiS₂, 0.1 mol Sb₂S₅, 0.03 mol Al₂S₃, 0.05 mol In₂S₃, and 0.04 mol SrS, yielding Li₂S electrolytes with a median particle size D₅₀ of 1 μm. 4.04 Si 0.6 Sb 0.2 (In 0.5 Al 0.3 Sr 0.2 ) 0.2 S4 electrolyte material. The Li obtained in this embodiment was used in the preparation of the positive and negative electrode sheets. 4.04 Si 0.6 Sb 0.2 (In 0.5 Al 0.3 Sr 0.2 ) 0.2 The preparation steps for the S4 electrolyte material and other batteries are the same as in Example 1.

[0058] Example 4 In the preparation of high-entropy sulfide electrolytes, the raw materials were 1.9 mol Li₂S, 0.05 mol Na₂S, 0.05 mol K₂S, 0.6 mol SiS₂, 0.1 mol Sb₂S₅, and 0.1 mol Al₂S₃, yielding Li₂S electrolytes with a median particle size D₅₀ of 1 μm. 3.8 Na 0.1 K 0.1 Si 0.6 Sb 0.2 Al 0.2 S4 electrolyte material. The Li obtained in this embodiment was used in the preparation of the positive and negative electrode sheets. 3.8 Na 0.1 K 0.1 Si 0.6 Sb 0.2 Al 0.2 The preparation steps for the S4 electrolyte material and other batteries are the same as in Example 1.

[0059] Example 5 In the preparation of high-entropy sulfide electrolytes, the raw materials were 1.7 mol Li₂S, 0.6 mol SiS₂, 0.1 mol Sb₂S₅, 0.1 mol Al₂S₃, 0.2 mol Li₂O, and 0.1 mol Li₂Te, yielding Li₄Si with a median particle size D₅₀ of 1 μm. 0.6 Sb 0.2 Al 0.2 S 3.7 O 0.2 Te 0.1 Electrolyte material. The Li4Si obtained in this embodiment was used in the preparation of the positive and negative electrode sheets. 0.6 Sb 0.2 Al 0.2 S 3.7 O 0.2 Te 0.1 The electrolyte material and the preparation steps for other batteries are the same as in Example 1.

[0060] Example 6 When preparing the solid electrolyte layer, the thickness of the first electrolyte layer is 1 μm, and the preparation steps of other batteries are the same as in Example 3.

[0061] Example 7 When preparing the solid electrolyte layer, the thickness of the first electrolyte layer is 30 μm, and the preparation steps of the other batteries are the same as in Example 3.

[0062] Example 8 When preparing the solid electrolyte layer, the thickness of the first electrolyte layer is 50 μm, and the preparation steps of the other batteries are the same as in Example 3.

[0063] Example 9 When preparing the solid electrolyte layer, the thickness of the first electrolyte layer is 100 μm, and the preparation steps of the other batteries are the same as in Example 3.

[0064] Example 10 When preparing the solid electrolyte layer, the thickness of the first electrolyte layer is 200 μm, and the preparation steps of the other batteries are the same as in Example 3.

[0065] Example 11 When preparing the solid electrolyte layer, the thickness of the first electrolyte layer is 500 μm, and the preparation steps of the other batteries are the same as in Example 3.

[0066] Example 12 In preparing the solid electrolyte layer, COFs are selected from triazine ring COFs particles. 1,3,5-tricyanobenzene is used as the first monomer and terephthalonitrile is used as the second monomer in the preparation of the COF triazine ring COFs particles. The preparation steps of other batteries are the same as in Example 3.

[0067] Example 13 In preparing the solid electrolyte layer, the COFs were selected from benzothiazole COFs sheets. The benzothiazole COFs sheets were prepared using 2-aminobenzylthiophenol as the first monomer and terephthalaldehyde as the second monomer. The preparation steps of other batteries were the same as in Example 3.

[0068] Example 14 In preparing the solid electrolyte layer, COFs are selected from borate COFs sheets. 1,4-phenyldiboronic acid is used as the first monomer and 2,3,6,7,10,11-hexahydroxytriphenyl as the second monomer in the preparation of the borate COFs sheets. The preparation steps of other batteries are the same as in Example 3.

[0069] Example 15 In the preparation of the solid electrolyte layer, the COF content in the second electrolyte layer is 1 wt%, and the preparation steps of other batteries are the same as in Example 3.

[0070] Example 16 In the preparation of the solid electrolyte layer, the COF content in the second electrolyte layer is 10 wt%, and the preparation steps of other batteries are the same as in Example 3.

[0071] Example 17 In the preparation of the solid electrolyte layer, the COF content in the second electrolyte layer is 15 wt%, and the preparation steps of other batteries are the same as in Example 3.

[0072] Example 18 In the preparation of the solid electrolyte layer, the COF content in the second electrolyte layer is 25 wt%, and the preparation steps of other batteries are the same as in Example 3.

[0073] Example 19 In the preparation of the solid electrolyte layer, the COF content in the second electrolyte layer is 30 wt%, and the preparation steps of other batteries are the same as in Example 3.

[0074] Example 20 In the preparation of the solid electrolyte layer, the COF content in the second electrolyte layer is 50 wt%, and the preparation steps of other batteries are the same as in Example 3.

[0075] Example 21 In the preparation of the solid electrolyte layer, the COF content in the second electrolyte layer is 55 wt%, and the preparation steps of other batteries are the same as in Example 3.

[0076] Example 22 When preparing the solid electrolyte layer, the thickness of the second electrolyte layer is 1 μm, and the preparation steps of other batteries are the same as in Example 3.

[0077] Example 23 When preparing the solid electrolyte layer, the thickness of the second electrolyte layer is 10 μm, and the preparation steps of other batteries are the same as in Example 3.

[0078] Example 24 When preparing the solid electrolyte layer, the thickness of the second electrolyte layer is 40 μm, and the preparation steps of other batteries are the same as in Example 3.

[0079] Example 25 When preparing the solid electrolyte layer, the thickness of the second electrolyte layer is 50 μm, and the preparation steps of other batteries are the same as in Example 3.

[0080] Example 26 When preparing the solid electrolyte layer, the thickness of the second electrolyte layer is 100 μm, and the preparation steps of other batteries are the same as in Example 3.

[0081] Example 27 When preparing the solid electrolyte layer, the thickness of the second electrolyte layer is 150 μm, and the preparation steps of other batteries are the same as in Example 3.

[0082] Comparative Example 1 In preparing the high-entropy sulfide electrolyte, the raw materials were 2 mol of Li₂S and 1 mol of SnS₂, resulting in a Li₄SnS₄ electrolyte material with a median particle size D₅₀ of 1 μm. The Li₄SnS₄ electrolyte material was used in preparing the positive and negative electrode sheets; the preparation steps for other batteries were the same as in Example 3.

[0083] Comparative Example 2 In the preparation of the solid electrolyte layer, only the first electrolyte layer is included, and the second electrolyte layer is not formed. The preparation steps of other batteries are the same as in Example 3.

[0084] Comparative Example 3 In the preparation of the solid electrolyte layer, only the second electrolyte layer is included, and the first electrolyte layer is not formed. The preparation steps of other batteries are the same as in Example 3.

[0085] Comparative Example 4 In the preparation of the solid electrolyte layer, the COF content in the second electrolyte layer is 0 wt%, and the preparation steps of other batteries are the same as in Example 3.

[0086] In this invention, some features of the solid electrolyte layer in Examples 1-27 and Comparative Examples 1-4 are shown in Table 1. The performance of the all-solid-state batteries in Examples 1-27 and Comparative Examples 1-4 was tested, and the test results were recorded. The test results are shown in Table 2.

[0087] Table 1. Partial parameters of the solid electrolyte layer in Examples 1-27 and Comparative Examples 1-4

[0088] In one embodiment of the present invention, to obtain room temperature cycling performance, the all-solid-state batteries prepared in the examples and comparative examples were subjected to a low pressure of 1 MPa at 25°C and normal pressure. After activation at a rate of 0.05C for two cycles within an operating voltage range of 2.5V to 4.3V, they were then charged and discharged at a rate of 1C / 1C (1C rated current density is 4 mA / cm²). 2 Record the discharge capacity of the battery in the first cycle after activation, which is the first 1C discharge capacity Q0. Record the capacity at 1000 battery cycles as Q1. Calculate the capacity retention rate after 1000 cycles of 1C / 1C at room temperature using the following formula: Capacity retention rate after 1000 cycles = (Q1 / Q0) × 100%.

[0089] In one embodiment of the present invention, to obtain the Direct Current Resistance (DCR) at 50% State of Charge (50% SOC), the temperature of the temperature chamber is kept constant at 25°C. The all-solid-state batteries obtained in the embodiment and the comparative example are placed in the temperature chamber for 10 minutes. The batteries are then charged at a constant current rate of 0.33C to 4.3V, followed by a constant voltage rate of 0.05C. After standing for 10 minutes, they are discharged at 0.33C to 2.5V to obtain the theoretical capacity of the battery. Subsequently, the batteries are charged again at a constant current rate of 0.33C to 4.3V, followed by a constant voltage rate of 0.05C. After standing for 10 minutes, they are discharged at 0.33C to adjust the capacity to 50% SOC. After standing for 1 hour, the initial voltage V1 of the battery is recorded. Then, the battery is discharged at a current of 4C I0 for 30 seconds, and the battery voltage V2 after discharge is recorded. The DCR of the battery at 50% SOC is calculated according to the following formula: DCR(Ω)=(V1-V2) / I0.

[0090] In one embodiment of the present invention, the rate performance test is conducted at 25°C by applying a low pressure of 1 MPa to the all-solid-state batteries assembled in the examples and comparative examples, at a rate of 0.05C (1C rated current density is 4 mA / cm²). 2 After two cycles of activation at the high rate, charge at 0.33C to 4.3V and let stand for 5 minutes. Then, discharge at different rates (e.g., 0.33C, 0.5C, 1C, 2C) to 2.5V. The specific process is as follows: charge at 0.33C, then discharge at 0.33C, repeat 3 times, and record the average discharge capacity at 0.33C; then charge at 0.33C and discharge at 0.5C, repeat 3 times; then charge at 0.33C and discharge at 1C, repeat 3 times; then charge at 0.33C and discharge at 2C, repeat 3 times, and record the average discharge capacity at 2C. Calculate the fast charging capacity retention rate at the high rate of 2C using the following formula: Fast charging capacity retention rate (%) = (Average discharge capacity at 2C / Average discharge capacity at 0.33C) × 100%.

[0091] Table 2 shows the performance of all-solid-state batteries in Examples 1-27 and Comparative Examples 1-4.

[0092] Please refer to Tables 1 and 2. Comparing Examples 1 to 5, Comparative Examples 1 and 3, it can be seen that when the first electrolyte layer includes a high-entropy sulfide electrolyte, compared to conventional sulfide electrolytes, such as Comparative Example 1 using Li4SnS4, and compared to Comparative Example 3 without a first electrolyte layer, the all-solid-state battery exhibits significant advantages in cycle stability, interfacial impedance DCR, and fast-charging performance when it contains high-entropy sulfide electrolytes with different structures. This is because the high-entropy sulfide electrolyte effectively suppresses grain boundary migration and phase transition through its multi-principal solid solution structure, improves interfacial chemical stability and mechanical flexibility, and reduces Young's modulus to achieve "flexible wetting" with the positive electrode active material, thereby maintaining a stable ion pathway under a low stacking pressure of 1 MPa. In contrast, conventional sulfide electrolytes are prone to increased interfacial side reactions and dendrite penetration risk due to their single composition. The lack of sulfide electrolyte in the solid electrolyte layer cannot provide high conductivity and oxidation stability support, resulting in a sharp increase in interfacial impedance and accelerated cycle decay. In addition, the high-entropy design endows the first electrolyte layer with excellent thermodynamic stability, which can work together with the LiF / Li3N protective layer induced by COFs on the negative electrode side to jointly construct a bistable interface system between the positive and negative electrodes.

[0093] Please refer to Tables 1 and 2. A comparison of Examples 3, 6, to 11 shows that as the thickness of the first electrolyte layer in the solid electrolyte layer increases, the all-solid-state battery exhibits the following characteristics: first, the cycle capacity initially increases and then decreases; second, the interface resistance (DCR) initially decreases and then increases; and third, the fast-charging capacity initially increases and then decreases. Specifically, when the thickness of the first electrolyte layer is 45 μm, the interface resistance is lowest, and the cycle capacity retention and fast-charging performance are optimal. When the thickness of the first electrolyte layer decreases to 1 μm, although the ion transport resistance is reduced, insufficient mechanical strength makes it susceptible to dendrite penetration, leading to an increase in DCR and a decrease in capacity retention. When the thickness of the first electrolyte layer increases to 50-200 μm, the ion diffusion path lengthens, internal resistance increases, causing the DCR to gradually increase, fast-charging performance to decrease, and the stacking pressure requirement increases. When the thickness of the first electrolyte layer reaches 500 μm, not only is the conductivity of the first electrolyte layer limited, but the excessive rigidity also makes it difficult to meet the requirements of low-pressure batteries, resulting in a sharp drop in capacity retention and fast-charging performance. Therefore, the thickness of the first electrolyte layer is 1 μm to 200 μm, preferably 30 μm to 50 μm, to improve the performance of the all-solid-state lithium-ion battery.

[0094] Please refer to Tables 1 and 2. Comparing Examples 3, 12 to 14, and Comparative Example 4, it can be seen that when COFs with β-ketoenamine bonds, triazine rings, benzothiazoles, and imine bonds are used as fillers in the second electrolyte layer in these examples, the battery performance is significantly better than that of Comparative Example 4, which does not contain COFs. Comparative Example 4, lacking the ordered channels and heteroatom sites of COFsF, has low ionic conductivity, high interfacial impedance, and the worst fast-charging performance. Therefore, when using a second electrolyte layer containing COFs, continuous Li is constructed through periodic nanopores. + The transport pathway, with its N / O / S / F heteroatoms in the framework, can induce the formation of a dense, high-modulus LiF / Li3N composite SEI film in situ on the lithium metal surface, significantly reducing interfacial impedance and suppressing dendrite growth. Among them, β-keto-enamine COFs exhibit the best cycle retention and fast-charging capability due to their complete absence of NH, strong conjugated structure, and high chemical stability with high-entropy sulfide electrolytes. Triazine rings and benzothiazoles also show significantly better battery performance than Comparative Example 4 due to their high inertness and interfacial compatibility. In the borate ester COFs of Example 14, when in contact with high-entropy sulfide electrolytes, the borate ester bonds are easily hydrolyzed to generate B(OH)3 and release H2S in the presence of trace amounts of moisture, resulting in slightly poorer battery performance.

[0095] Please refer to Tables 1 and 2. Comparing Examples 3, 14 to 21 and Comparative Example 4, it can be seen that as the COF content in the second electrolyte layer gradually increases from 0 wt% to 30 wt%, the performance of the all-solid-state battery shows a trend of first significantly improving and then tending to saturate or even slightly decreasing. Comparative Example 4, which does not contain COFs, exhibits the highest interfacial impedance due to the lack of ordered ion channels and interface regulation sites. When the COF content is between 15 wt% and 25 wt%, the performance of the all-solid-state battery reaches its peak. This is because at this content, COFs construct a highly efficient Li... + The continuous transport network provides sufficient N / F heteroatoms to form a uniform and dense LiF / Li3N protective layer in situ, while also ensuring the flexibility and film integrity of the polymer in the second electrolyte layer. However, when the COF content is below 10 wt%, insufficient COFs result in limited improvement in ionic conductivity and weak interface stabilization. When the COF content exceeds 30 wt%, COFs are prone to aggregation, disrupting the continuous polymer phase, leading to increased film brittleness and deteriorated interfacial contact, which in turn increases DCR and reduces cycle and fast-charging performance. Therefore, the COF content in the second electrolyte layer is 1 wt% to 50 wt%, preferably 10 wt% to 30 wt%, and more preferably 15 wt% to 25 wt%, to improve the performance of the all-solid-state lithium-ion battery.

[0096] Please refer to Tables 1 and 2. A comparison of Examples 3, 22 to 27, and Comparative Example 2 shows that as the thickness of the second electrolyte layer in the solid electrolyte layer increases, the all-solid-state battery exhibits a consistent pattern: cycle capacity initially increases and then decreases; interface resistance (DCR) initially decreases and then increases; and fast-charging capacity initially increases and then decreases. Specifically, the battery exhibits optimal electrochemical performance when the thickness of the second electrolyte layer is 20 μm, indicating that this thickness provides good flexibility, effective adhesion to the negative electrode, and a suitable ion transport path. When the thickness of the second electrolyte layer decreases to 1 μm, although ion migration resistance is reduced, insufficient mechanical strength makes it difficult to suppress dendrite penetration and negative electrode layer expansion, leading to decreased interface stability. When the thickness of the second electrolyte layer increases to 40 μm to 150 μm, the DCR gradually increases due to the extended ion diffusion distance and increased internal resistance, resulting in a significant decrease in fast-charging performance. Comparative Example 2 lacks a second electrolyte layer, making it difficult to maintain good interface contact under low pressure. During battery cycling, changes in the negative electrode volume lead to interface deterioration and increased interface resistance. Therefore, the thickness of the second electrolyte layer is 1 μm to 100 μm, preferably 10 μm to 40 μm, to improve the performance of the all-solid-state lithium-ion battery.

[0097] This invention also provides an electronic device comprising at least one of the aforementioned all-solid-state batteries, which provides electrical energy. The electronic device can be a vehicle, mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, or power tool, etc. In one embodiment of this invention, the vehicle is, for example, a new energy vehicle, which can be a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The electronic device includes the aforementioned all-solid-state battery, and therefore the advantages of including the aforementioned all-solid-state battery are not elaborated here.

[0098] In summary, this invention proposes a solid electrolyte layer and its application. The high-entropy sulfide electrolyte in the first electrolyte layer effectively suppresses grain boundary migration and phase transition through a multi-principal solid solution structure, improving interfacial chemical stability and mechanical flexibility, and reducing Young's modulus to achieve "flexible wetting" with the positive electrode active material, thereby maintaining a stable ion pathway under a low stacking pressure of 1 MPa. The first electrolyte layer combines high oxidation stability, low Young's modulus, and high ionic conductivity, enabling good wetting with the positive electrode active material through a flexible transition in all-solid-state batteries, maintaining a good ion pathway without high pressure. The polymer in the second electrolyte layer has excellent flexibility and viscoelasticity, allowing it to tightly adhere to the surface of the negative electrode sheet under conditions not exceeding 1 MPa, filling microscopic voids and achieving excellent interfacial compatibility on the negative electrode side. The fluorine element in the fluorinated polyimide and the nitrogen and oxygen functional groups in the COFs framework work synergistically on the lithium metal surface to generate a uniform and dense LiF / Li3N composite solid electrolyte interfacial film in situ, which can significantly reduce interfacial impedance and suppress side reactions and dendrite growth. Furthermore, the LiF / Li3N interface layer induced by COFs possesses self-healing properties, further reducing interfacial contact resistance. By adding lithium salt to the second electrolyte layer and controlling the content of various substances within it, the ionic conductivity of the second electrolyte layer can be improved, interfacial stability can be regulated, and mechanical and thermal stability optimized. The solid electrolyte layer, constructed with a bilayer electrolyte structure, exhibits different properties on both sides, achieving a balance between high flexibility, high mechanical strength, and excellent long-cycle stability, thereby enhancing the performance of the all-solid-state battery.

[0099] The above description is merely a preferred embodiment of this application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept. For example, technical solutions formed by replacing the above-mentioned features with technical features with similar functions disclosed in this application (but not limited to) each other.

[0100] Apart from the technical features described in the specification, the other technical features are known to those skilled in the art. To highlight the innovative features of this invention, the other technical features will not be described in detail here.

Claims

1. A solid electrolyte layer, characterized in that, include: A first electrolyte layer, comprising a high-entropy sulfide electrolyte, wherein the chemical formula of the high-entropy sulfide electrolyte is: Li 4±x-y A y (M1 a M2 b M3 c S4 δ X δ Where 0≤x≤1.5, 0≤y≤1.5, and y≤4±x; 0.4≤a≤0.8, 0.1≤b≤0.4, 0.1≤c≤0.3, a+b+c=1, 0≤δ≤1; A is selected from one or two of Na or K; M1 is selected from one or more of Ge, Sn, Si, P, As or B; M2 is selected from one or more of Sb, Nb, Ta, V, Mo, W, Ti, Zr, Hf or Re; M3 is selected from one or more of Al, Ga, In, Bi, Pb, Mg, Ca, Zn, Cd, Y, Sc, La, Ba, Sr, Ce or Sm; X is selected from one or more of O, Se or Te. A second electrolyte layer is disposed on one side surface of the first electrolyte layer, and the second electrolyte layer comprises a polymer and a covalent organic framework material.

2. The solid electrolyte layer according to claim 1, characterized in that, The thickness of the first electrolyte layer is 1 μm to 200 μm; and / or, the thickness of the second electrolyte layer is 1 μm to 100 μm.

3. The solid electrolyte layer according to claim 1, characterized in that, The thickness of the first electrolyte layer is 30 μm to 50 μm; and / or, the thickness of the second electrolyte layer is 10 μm to 40 μm.

4. The solid electrolyte layer according to claim 1, characterized in that, The conductivity of the first electrolyte layer is 1×10 -3 S / cm to 2×10 -2 S / cm; and / or, the conductivity of the second electrolyte layer is 1×10⁻⁶. -5 S / cm to 1×10 -3 S / cm.

5. The solid electrolyte layer according to claim 4, characterized in that, The framework of the covalent organic framework material contains at least one heteroatom selected from nitrogen, oxygen, fluorine, or sulfur; the framework is formed by at least one covalent linking group selected from imine bond, hydrazone bond, β-ketoenamine bond, borate ester bond, triazine ring, benzoxazole, benzothiazole, imide bond, or urea bond.

6. The solid electrolyte layer according to claim 5, characterized in that, The covalent organic framework material has a two-dimensional or three-dimensional periodic topological structure, and the covalent organic framework material has a periodic nanopore structure; and / or, the pore size of the covalent organic framework material is 1 nm to 3 nm, and the specific surface area of ​​the covalent organic framework material is greater than or equal to 500 m². 2 / g.

7. The solid electrolyte layer according to claim 1, characterized in that, The covalent organic framework material is nanoparticles or nanosheets; the median particle size of the nanoparticles is 50 nm to 5 μm; the diameter of the nanosheets is 50 nm to 5 μm and the thickness is 2 nm to 100 nm.

8. The solid electrolyte layer according to claim 1, characterized in that, The second electrolyte layer further includes a lithium salt selected from at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium bisfluorosulfonylimide, lithium hexafluorophosphate, or lithium dioxaborate.

9. The solid electrolyte layer according to claim 8, characterized in that, The polymer includes fluorinated polyimide, and / or the mass ratio of the polymer, the covalent organic framework material and the lithium salt is (35 to 98):(1 to 50):(1 to 15).

10. An all-solid-state battery, characterized in that, include: Positive electrode sheet; Negative electrode plate; as well as A solid electrolyte layer is disposed between the positive electrode and the negative electrode, and is selected from the solid electrolyte layer according to any one of claims 1 to 9, wherein the first electrolyte layer of the solid electrolyte layer is located on the side closer to the positive electrode.

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