Composite solid electrolyte and preparation method and application thereof

Abstract

The invention provides a composite solid electrolyte as well as a preparation method and application thereof, and the composite solid electrolyte comprises the following raw materials in parts by weight: 50-100 parts of inorganic filler; 5 to 15 parts of a plasticizer; 5 to 15 parts of lithium salt; 1-5 parts of a cross-linking agent and 5-20 parts of a chain extender. The composite solid electrolyte comprises the inorganic filler, the plasticizer, the lithium salt, the cross-linking agent, the chain extender and other components, complex physical and chemical interaction exists among the components, and the composite solid electrolyte with high ionic conductivity, excellent mechanical performance and electrochemical stability is jointly constructed. Through performance optimization of the composite electrolyte, the problems of large thickness, high brittleness and poor interface contact of a traditional inorganic solid electrolyte layer are solved, and powerful technical support is provided for development and commercial application of a solid-state battery.

Description

Technical Field

[0001] This invention relates to the field of solid-state lithium battery technology, and more specifically, to a composite solid electrolyte, its preparation method, and its application. Background Technology

[0002] As a novel energy storage device, all-solid-state lithium metal batteries have become an ideal choice for next-generation battery technology due to their high energy density, long lifespan, and safety performance. Compared with traditional liquid lithium-ion batteries, all-solid-state lithium metal batteries effectively avoid the safety hazards caused by liquid electrolytes, such as flammability, leakage, and instability, by using a solid electrolyte instead of a liquid electrolyte and separator, thereby greatly improving the overall safety and reliability of the battery.

[0003] In all-solid-state lithium metal batteries, solid electrolytes play a crucial role. They not only serve as a medium for lithium-ion transport and maintain charge balance during battery charging and discharging, but also improve the overall energy density of the battery, broaden the electrochemical window, and enhance the cycle performance of all-solid-state batteries. The development of solid electrolyte technology is one of the key factors driving the commercialization of solid-state batteries.

[0004] Garnet-type inorganic solid-state electrolytes, among all-solid-state electrolytes, have become a research focus in the field of solid-state electrolytes due to their high ionic conductivity and good stability against lithium metal anodes. These electrolytes not only meet the requirements of high-voltage battery systems but also ensure the stability of the lithium metal anode during charge and discharge, significantly improving battery cycle life and energy efficiency. However, inherent defects in garnet-type inorganic solid-state electrolytes limit their widespread application. The most prominent problems include: Difficulty in reducing electrolyte layer thickness: Inorganic solid-state electrolytes typically require a large thickness to ensure sufficient mechanical strength and ion conductivity, but a thick electrolyte layer increases the battery's volume and weight, hindering energy density improvement. High brittleness: The brittleness of inorganic materials makes them prone to cracking during manufacturing, especially when pursuing thin-layer structures, directly threatening battery performance and safety. Poor interfacial contact: Problems with interfacial contact between the inorganic solid-state electrolyte and electrode materials lead to reduced ion conductivity, increased internal resistance, and severely affect battery cycle performance and energy density. In addition, the use of solvents in the preparation of conventional all-solid electrolytes may bring a series of problems when mixing electrolyte components. For example, the solvent treatment process is complicated and increases costs, solvent emissions cause environmental pollution, and solvent residues in solid electrolytes may affect battery performance.

[0005] In summary, improving the thickness and toughness of all-solid-state electrolytes, addressing interfacial contact issues, enhancing ion conduction efficiency, and simultaneously resolving the adverse effects of solvent residues in all-solid-state electrolytes are key factors in further enhancing the performance of all-solid-state lithium metal batteries. Summary of the Invention

[0006] The main objective of this invention is to provide a composite solid electrolyte, its preparation method, and its application, in order to solve the problems of large electrolyte thickness, insufficient toughness, and poor interfacial contact in existing all-solid-state batteries, while also addressing the adverse effects of solvent residue, aiming to further improve the performance of all-solid-state lithium metal batteries.

[0007] This application provides a composite solid electrolyte, wherein the raw materials of the composite solid electrolyte include, by weight: inorganic filler: 50-100 parts; plasticizer: 5-15 parts; lithium salt: 5-15 parts; crosslinking agent: 1-5 parts; chain extender: 5-20 parts.

[0008] Furthermore, by weight, the raw materials for the composite solid electrolyte include: inorganic filler: 60-100 parts; plasticizer: 10-15 parts; lithium salt: 10-15 parts; crosslinking agent: 1-5 parts; and chain extender: 10-20 parts.

[0009] Furthermore, in the raw materials of the composite solid electrolyte, the weight content of the crosslinking agent is 1-5%; and / or, in the raw materials of the composite solid electrolyte, the weight content of the chain extender is 10-20%.

[0010] Furthermore, the weight ratio of crosslinking agent to chain extender is (0.1 to 0.5):1.

[0011] Further, the crosslinking agent is at least one of an epoxide alkyl polymer or an epoxy compound; and / or, the number average molecular weight of the crosslinking agent is 200 to 2000; and / or, the crosslinking agent is one or more of polyethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, resorcinol diglycidyl ether, glycerol triglycidyl ether, and neopentyl glycol diglycidyl ether.

[0012] Further, the chain extender is an amine chain extender and / or a polysiloxane chain extender; and / or, the chain extender is one or more of p-phenylenediamine, 1,8-octanediamine, polyoxyethylenediamine, poly(dimethylsiloxane)bis(3-aminopropyl)-terminated and adipamide.

[0013] Furthermore, the inorganic filler is selected from one or more of LLZTO, LLZO, LAGP, alumina, silica, and titanium dioxide; and / or, the plasticizer is selected from one or more of succinic anhydride, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and N-methylacetamide; and / or, the lithium salt is selected from one or more of LiFSI, LiBOB, LiPF6, LiClO4, LiTFSI, LiNO3, and LiDFOB.

[0014] According to another aspect of the present invention, a method for preparing the above-mentioned composite solid electrolyte is also provided. The method includes the following steps: mixing inorganic filler, plasticizer, lithium salt, crosslinking agent and chain extender and then pulverizing them to obtain a mixture; and subjecting the mixture to static pressure curing and heat curing to obtain a composite solid electrolyte.

[0015] Furthermore, the mixing operation is carried out in a glove box; and / or, the static pressure curing temperature is 50–100°C and the time is 5–30 min; and / or, the heat curing temperature is 40–100°C and the time is 1–5 h; and / or, the static pressure curing pressure is 100–300 MPa.

[0016] According to a third aspect of the present invention, a solid-state lithium battery is also provided, the solid-state lithium battery comprising the above-described composite solid electrolyte.

[0017] This invention provides a composite solid-state electrolyte. By weight, the raw materials of the composite solid-state electrolyte include: inorganic filler: 50-100 parts; plasticizer: 5-15 parts; lithium salt: 5-15 parts; crosslinking agent: 1-5 parts; and chain extender: 5-20 parts. The composite solid-state electrolyte of this application includes multiple components such as inorganic filler, plasticizer, lithium salt, crosslinking agent, and chain extender. These components exhibit complex physicochemical interactions, jointly constructing a composite solid-state electrolyte that combines high ionic conductivity, excellent mechanical properties, and electrochemical stability. This performance optimization of the composite electrolyte solves the problems of large layer thickness, high brittleness, and poor interfacial contact in traditional inorganic solid-state electrolytes, providing strong technical support for the development and commercial application of solid-state batteries. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 Impedance diagrams of the composite solid electrolyte prepared according to Example 1 of the present invention are shown;

[0020] Figure 2The room temperature cycling performance of a coin cell corresponding to the composite solid electrolyte prepared according to Example 1 of the present invention is shown.

[0021] Figure 3 The cycling performance of a Li / / Li symmetric coin cell corresponding to the composite solid electrolyte prepared according to Example 1 of the present invention is shown. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] As described in the background section, garnet-type inorganic solid-state electrolytes, among all-solid-state electrolytes, have become a research focus in the field of solid-state electrolytes due to their high ionic conductivity and good stability against lithium metal anodes. However, existing all-solid-state electrolytes suffer from problems such as large thickness, high brittleness, and poor interfacial contact, which seriously affect the cycle performance and energy density of all-solid-state batteries. In addition, the use of solvents in the preparation process of conventional all-solid-state electrolytes may bring a series of problems when mixing electrolyte components, such as complex solvent treatment processes that increase costs, environmental pollution caused by solvent emissions, and the potential impact of solvent residues in the solid-state electrolyte on battery performance.

[0024] To address the aforementioned problems, this invention provides a composite solid electrolyte. By weight, the raw materials of the composite solid electrolyte include: inorganic filler: 50-100 parts; plasticizer: 5-15 parts; lithium salt: 5-15 parts; crosslinking agent: 1-5 parts; and chain extender: 5-20 parts. The composite solid electrolyte of this application includes multiple components such as inorganic filler, plasticizer, lithium salt, crosslinking agent, and chain extender. These components exhibit complex physicochemical interactions, collectively constructing a high-performance solid electrolyte layer.

[0025] Specifically, the presence of inorganic fillers in the raw materials of composite solid-state electrolytes improves their ionic conductivity and electrochemical stability, and further broadens their electrochemical window. Especially with the synergistic effect of plasticizers, crosslinking agents, and chain extenders, composite solid-state electrolytes possess both good mechanical properties and improved flexibility and processability. This compensates for the brittleness and poor interfacial contact of inorganic fillers, allowing the composite solid-state electrolyte to resist bending or compressive stress even after thinning, preventing the composite solid-state electrolyte layer from cracking. This facilitates the preparation of thin and uniform continuous layers, resulting in composite solid-state electrolytes with superior ionic conductivity and other properties. Lithium salts play a role in providing lithium ions in the composite electrolyte. In particular, in the presence of plasticizers, lithium salts can better dissolve and dissociate to form freely moving lithium ions, accelerating their migration speed. This helps reduce the interfacial impedance of the composite solid-state electrolyte and improves the electrochemical performance of the all-solid-state battery. Plasticizers, with their low glass transition temperature (Tg), allow the composite electrolyte to remain soft and fluid at room temperature, reducing resistance to ion transport and mitigating the high brittleness of composite solid electrolytes. Crosslinking agents, by forming chemical crosslinking points between polymer chains, increase the network structure of the material, thereby improving the mechanical strength and toughness of the electrolyte. Furthermore, the presence of crosslinks restricts polymer chain movement, improving the material's thermal stability and allowing it to maintain stable performance at higher temperatures. The presence of crosslinks also reduces polymer swelling and dissolution in the electrolyte, thus improving the electrolyte's chemical stability. The addition of chain extenders introduces flexible segments, increasing polymer mobility and making the solid electrolyte more flexible. Chain extenders, through chain extension reactions, increase the polymer's molecular weight, thereby improving the material's mechanical properties and consequently, the ion conductivity in the electrolyte. The synergistic effect of chain extenders and crosslinking agents results in a crosslinked network structure that increases the mechanical strength and thermal stability of the composite solid electrolyte, while also providing a continuous conductive path for lithium ions, thus improving ionic conductivity. The composite solid electrolyte exhibits high ionic conductivity, good thermal stability, flame retardancy, a wide electrochemical window, and a high lithium-ion transference number, effectively improving the electrochemical performance of all-solid-state batteries.

[0026] In summary, the composite solid electrolyte provided by this invention, through the complex physicochemical interactions of various components such as inorganic fillers, plasticizers, lithium salts, crosslinking agents, and chain extenders in the raw materials of the composite solid electrolyte, and by controlling the proportions of these components within the aforementioned ranges, collectively constructs a composite solid electrolyte that possesses high ionic conductivity, excellent mechanical properties, and electrochemical stability. This performance optimization of the composite electrolyte solves the problems of large layer thickness, high brittleness, and poor interfacial contact in traditional inorganic solid electrolytes, providing strong technical support for the development and commercial application of solid-state batteries.

[0027] In a preferred embodiment, the raw materials for the composite solid-state electrolyte, by weight, include: 60-100 parts of inorganic filler; 10-15 parts of plasticizer; 10-15 parts of lithium salt; 1-5 parts of crosslinking agent; and 10-20 parts of chain extender. As described above, the composite solid-state electrolyte significantly improves its electrochemical performance through the synergistic effect of inorganic filler, plasticizer, lithium salt, crosslinking agent, and chain extender. Inorganic filler provides high ionic conductivity and electrochemical stability, broadening the electrochemical window; plasticizer keeps the electrolyte soft, promotes lithium salt dissolution, accelerates lithium ion migration, and reduces interfacial impedance; crosslinking agent and chain extender construct a stable conductive network structure, enhancing mechanical strength and thermal stability, and ensuring continuous lithium ion conduction. Through the combined action of these components, the prepared electrolyte exhibits high ionic conductivity, excellent thermal stability, and flame retardancy, greatly optimizing the electrochemical performance and safety of all-solid-state batteries. Controlling the proportions of each component within the above range can better leverage the synergistic effects, thereby further improving the overall electrochemical performance of the prepared composite solid-state electrolyte.

[0028] In a preferred embodiment, the crosslinking agent comprises 1-5% by weight of the raw materials for the composite solid electrolyte; and / or, the chain extender comprises 10-20% by weight of the raw materials for the composite solid electrolyte. The synergistic effect of the crosslinking agent and chain extender in the composite solid electrolyte significantly enhances the material's performance. The crosslinking agent strengthens the network structure of the composite solid electrolyte material by establishing chemical bonds between polymer chains, improving the electrolyte's mechanical strength, toughness, and thermal stability, maintaining performance stability even at high temperatures, reducing swelling and dissolution in the electrolyte, and enhancing chemical stability. The chain extender, by introducing flexible segments, increases the polymer's mobility and molecular weight, making the solid electrolyte more flexible and improving ion conductivity. Through the combined action of the crosslinking agent and chain extender, a robust and flexible crosslinked network is constructed in the electrolyte, not only improving the mechanical strength of the composite solid electrolyte but also providing an efficient conduction pathway for lithium ions, thereby significantly improving ion conductivity and optimizing the electrochemical performance and durability of the all-solid-state battery. Controlling the weight content of the crosslinking agent or chain extender in the raw materials of the composite solid electrolyte within the aforementioned range allows for better performance of the above-mentioned effects, which is beneficial for further improving the overall electrochemical performance of the composite solid electrolyte. Preferably, the weight content of the crosslinking agent in the raw materials of the composite solid electrolyte is 1.5–2.5%; more preferably, the weight content of the chain extender in the raw materials of the composite solid electrolyte is 12–16%. Controlling the weight content of the crosslinking agent and chain extender in the raw materials of the composite solid electrolyte within the aforementioned range allows for better performance of the composite solid electrolyte, which is beneficial for further improving its overall electrochemical performance.

[0029] In a preferred embodiment, the weight ratio of the crosslinking agent to the chain extender is (0.1–0.5):1. Controlling the weight ratio of the crosslinking agent to the chain extender within this range allows for better formation of a crosslinked network, thereby improving the mechanical strength and ion conduction pathway of the composite solid-state electrolyte, and enhancing the electrochemical performance and durability of the all-solid-state battery. Preferably, the weight ratio of the crosslinking agent to the chain extender is (0.1–0.3):1. Controlling the weight ratio of the crosslinking agent to the chain extender within the preferred range further enhances the above effects, resulting in better overall performance of the composite solid-state electrolyte.

[0030] In a preferred embodiment, the crosslinking agent is at least one of an epoxy alkyl polymer or an epoxy compound; preferably, the number average molecular weight of the crosslinking agent is 200-2000. Epoxy groups are active functional groups, which can better react with the active groups in the chain extender to construct a crosslinking network. The formed crosslinking network is beneficial to improving the overall stability of the composite material, especially its performance under high temperature and high pressure conditions, while also further reducing the swelling tendency of the polymer electrolyte and enhancing the chemical stability of the composite solid electrolyte. In particular, using a polymer with the above-mentioned number average molecular weight as a crosslinking agent is beneficial to better control the microstructure and performance of the composite electrolyte, further ensuring that the crosslinking network is neither too rigid to the point of brittle fracture nor too soft to lose its shape, providing a balanced transport environment for lithium ions, and further improving the overall conductivity of the composite solid electrolyte. Preferably, the crosslinking agent is one or more of polyethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, resorcinol diglycidyl ether, glycerol triglycidyl ether, and neopentyl glycol diglycidyl ether. Choosing the aforementioned crosslinking agents helps to better enhance the mechanical strength and toughness of the electrolyte, reduce its brittleness, and maintain good ionic conductivity.

[0031] In a preferred embodiment, the chain extender is an amine chain extender and / or a polysiloxane chain extender. The amino and siloxane groups in the chain extender can react with the active groups in the crosslinking agent, extending the polymer chains, increasing the degree of freedom of movement between chains, and thus improving the flexibility and ion conductivity of the electrolyte. This helps to further improve the tight contact between the electrolyte and the electrode during battery charging and discharging, reducing interfacial impedance. Preferably, the chain extender is one or more of p-phenylenediamine, 1,8-octanediamine, polyoxyethylenediamine, poly(dimethylsiloxane)bis(3-aminopropyl)-terminated, and adipamide. Selecting the above-mentioned specific chain extenders can better promote the dissociation and conduction of lithium ions, optimizing conductivity and battery cycle performance.

[0032] In a preferred embodiment, the inorganic filler is selected from LLZTO (Li 6.25 Al 0.25 La3Zr2O), LLZO(Li7La3Zr2O) 12 ), LAGP (Li 1.5 Al 0.5 Ti 1.5(PO4)3), one or more of alumina, silicon dioxide, and titanium dioxide; fillers such as LLZTO, LLZO, and LAGP possess high lithium-ion conductivity and stable electrochemical performance. Their addition enhances the electrochemical window and ion transport capability of the composite electrolyte, while also improving the mechanical strength and thermal stability of the material. Preferably, the inorganic filler is selected from one or more of LLZTO, LLZO, and LAGP. The above-mentioned types of inorganic fillers are beneficial to further improving the comprehensive electrochemical performance of the composite solid electrolyte. Preferably, the plasticizer is selected from one or more of succinic anhydride, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and N-methylacetamide; preferably, the lithium salt is selected from one or more of LiFSI, LiBOB, LiPF6, LiClO4, LiTFSI, LiNO3, and LiDFOB. The above-mentioned types of plasticizers and lithium salts can better exert their effects and are beneficial to improving the ionic conductivity and other properties of the obtained composite solid electrolyte.

[0033] According to another aspect of the present invention, a method for preparing the above-mentioned composite solid electrolyte is also provided. This method includes the following steps: mixing and pulverizing an inorganic filler, plasticizer, lithium salt, crosslinking agent, and chain extender to obtain a mixture; and then subjecting the mixture to static pressure curing and heat curing to obtain the composite solid electrolyte. In the above preparation method, the raw materials for the composite solid electrolyte, such as the inorganic filler, plasticizer, lithium salt, crosslinking agent, and chain extender, are first mixed and then pulverized to obtain a uniformly mixed mixture with a small particle size. Then, the obtained mixture is subjected to static pressure curing and heat curing to obtain the composite solid electrolyte.

[0034] In particular, the presence of crosslinking agents and chain extenders in the preparation of the aforementioned composite solid-state electrolyte enables the formation of a polymer network structure in the mixed system. Therefore, no solvent is needed during preparation, achieving good contact between the components and resulting in a composite solid-state electrolyte with excellent conductivity. This solvent-free process is not only environmentally friendly but also simplifies the production process, reduces energy consumption, and improves the economics of the composite solid-state electrolyte. Furthermore, in terms of improving the performance of the composite solid-state electrolyte, the solvent-free thermosetting process promotes more direct and effective interactions and crosslinking between components, avoiding performance degradation caused by solvent residue. This is beneficial for improving the ionic conductivity of the prepared composite solid-state electrolyte and optimizing electrochemical performance. Simultaneously, this method produces a thinner electrolyte layer, effectively alleviating battery internal resistance and increasing battery energy density. Finally, the composite electrolyte prepared by the solvent-free thermosetting method performs better under high-temperature conditions, ensuring safe battery operation. In summary, solvent-free thermosetting composite solid-state electrolytes not only demonstrate advantages in environmental protection and cost control but also achieve significant improvements in battery performance, safety, and applicability, indicating that they will become an important driving force for the development of solid-state battery technology.

[0035] In a preferred embodiment, the mixing operation is carried out in a glove box; the anhydrous and oxygen-free operation in the glove box allows for better performance of raw materials such as inorganic fillers, plasticizers, and lithium salts; and / or, the static pressure curing temperature is 50–100°C, and the time is 5–30 min; and / or, the heat curing temperature is 40–100°C, and the time is 1–5 h; and / or, the static pressure curing pressure is 100–300 MPa; and / or, the pulverization method is ball milling or grinding. Controlling the parameters in the preparation process within the above preferred ranges can further improve the performance of the prepared composite solid electrolyte.

[0036] Preferably, the mixture is subjected to a first heating curing, a static pressure curing, and a second heating curing sequentially to obtain a composite solid electrolyte. Preferably, the first and second heating curing temperatures are 40–100°C, and the times are 1–5 hours, with the first and second heating curing temperatures and times being independent of each other. Preferably, the static pressure curing temperature is 50–100°C, and the time is 5–30 minutes. Preferably, the static pressure curing pressure is 100–300 MPa. The above curing methods provide better results.

[0037] According to a third aspect of the present invention, a solid-state lithium battery is also provided, the solid-state lithium battery comprising the above-described composite solid electrolyte.

[0038] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0039] Example 1

[0040] By weight, 80 parts of inorganic filler (LLZTO), 10 parts of plasticizer (N-methylacetamide), 10 parts of lithium salt (LiTFSI), 2.4 parts of crosslinking agent (glycerol triglycidyl ether), and 17.6 parts of chain extender (poly(dimethylsiloxane) bis(3-aminopropyl)-terminated) were mixed and ground for 2 hours to obtain a dough-like mixture. This mixture was placed between two PP films, first cured in a vacuum oven at 60°C for 1.5 hours, then statically cured at 60°C (200 MPa) for 10 minutes, and finally further cured at 60°C for 2 hours to obtain a composite solid electrolyte.

[0041] Example 2

[0042] By weight, 80 parts of inorganic filler (LLZTO), 10 parts of plasticizer (butadienenitrile), 10 parts of lithium salt (LiTFSI), 2.4 parts of crosslinking agent (resorcinol diglycidyl ether), and 17.6 parts of chain extender (p-phenylenediamine) were mixed and ground for 2 hours to obtain a dough-like mixture. This mixture was placed between two PP films and first cured in a vacuum oven at 100°C for 1 hour, then statically cured at 50°C (100 MPa) for 30 minutes, and finally further cured at 40°C for 5 hours to obtain a composite solid electrolyte.

[0043] Example 3

[0044] By weight, 80 parts of inorganic filler (LLZTO), 10 parts of plasticizer (diethylene glycol dimethyl ether), 10 parts of lithium salt (LiTFSI), 2.4 parts of crosslinking agent (1,4-butanediol diglycidyl ether), and 17.6 parts of chain extender (adipamide) were mixed and ground for 2 hours to obtain a dough-like mixture. This mixture was placed between two PP films, first cured in a vacuum oven at 40°C for 5 hours, then statically cured at 100°C (300 MPa) for 5 minutes, and finally further cured at 100°C for 1 hour to obtain a composite solid electrolyte.

[0045] Example 4

[0046] The difference between Example 4 and Example 1 is the proportion of the all-solid electrolyte raw materials. Specifically:

[0047] By weight, the all-solid electrolyte raw materials include: 60 parts of inorganic filler (LLZTO), 10 parts of plasticizer (N-methylacetamide), 10 parts of lithium salt (LiTFSI), 2.4 parts of crosslinking agent (glycerol triglycidyl ether), and 17.6 parts of chain extender (poly(dimethylsiloxane) bis(3-aminopropyl) capped).

[0048] Example 5

[0049] The difference between Example 5 and Example 1 is the raw material for the all-solid electrolyte. Specifically:

[0050] By weight, it contains 80 parts of inorganic filler (LAGP), 10 parts of plasticizer (N-methylacetamide), 10 parts of lithium salt (LiTFSI), 2.4 parts of crosslinking agent (glycerol triglycidyl ether), and 17.6 parts of chain extender (poly(dimethylsiloxane) bis(3-aminopropyl) capped).

[0051] Example 6

[0052] The difference between Example 6 and Example 1 is the proportion of the all-solid electrolyte raw materials. Specifically:

[0053] By weight, 50 parts inorganic filler (LLZTO), 5 parts plasticizer (N-methylacetamide), 5 parts lithium salt (LiTFSI), 1 part crosslinking agent (glycerol triglycidyl ether), and 5 parts chain extender (poly(dimethylsiloxane) bis(3-aminopropyl) capped).

[0054] Example 7

[0055] The difference between Example 7 and Example 1 is the proportion of the all-solid electrolyte raw materials. Specifically:

[0056] By weight, 100 parts inorganic filler (LLZTO), 15 parts plasticizer (N-methylacetamide), 15 parts lithium salt (LiTFSI), 5 parts crosslinking agent (glycerol triglycidyl ether), and 20 parts chain extender (poly(dimethylsiloxane) bis(3-aminopropyl) capped).

[0057] Example 8

[0058] The difference between Example 8 and Example 1 is the proportion of the all-solid electrolyte raw materials. Specifically:

[0059] By weight, 60 parts of inorganic filler (LLZTO), 10 parts of plasticizer (N-methylacetamide), 10 parts of lithium salt (LiTFSI), 1 part of crosslinking agent (glycerol triglycidyl ether), and 10 parts of chain extender (poly(dimethylsiloxane) bis(3-aminopropyl) capped).

[0060] Example 9

[0061] The difference between Example 9 and Example 1 is the proportion of the all-solid electrolyte raw materials. Specifically:

[0062] By weight, 80 parts of inorganic filler (LLZTO), 10 parts of plasticizer (N-methylacetamide), 10 parts of lithium salt (LiTFSI), 5 parts of crosslinking agent (glycerol triglycidyl ether), and 10 parts of chain extender (poly(dimethylsiloxane) bis(3-aminopropyl) capped).

[0063] Example 10

[0064] The difference between Example 10 and Example 1 is the proportion of the all-solid electrolyte raw materials. Specifically:

[0065] By weight, 80 parts of inorganic filler (LLZTO), 10 parts of plasticizer (N-methylacetamide), 10 parts of lithium salt (LiTFSI), 1 part of crosslinking agent (glycerol triglycidyl ether), and 20 parts of chain extender (poly(dimethylsiloxane) bis(3-aminopropyl) capped).

[0066] Example 11

[0067] The difference between Example 11 and Example 1 is the proportion of the all-solid electrolyte raw materials. Specifically:

[0068] By weight, 80 parts of inorganic filler (LLZTO), 10 parts of plasticizer (N-methylacetamide), 10 parts of lithium salt (LiTFSI), 1 part of crosslinking agent (glycerol triglycidyl ether), and 8 parts of chain extender (poly(dimethylsiloxane) bis(3-aminopropyl) capped).

[0069] Comparative Example 1

[0070] The difference between Comparative Example 1 and Example 1 is the proportion of the all-solid electrolyte raw materials. Specifically:

[0071] By weight, it contains 40 parts of inorganic filler (LLZTO), 10 parts of plasticizer (N-methylacetamide), 10 parts of lithium salt (LiTFSI), 2.4 parts of crosslinking agent (glycerol triglycidyl ether), and 17.6 parts of chain extender (poly(dimethylsiloxane) bis(3-aminopropyl) capped).

[0072] Comparative Example 2

[0073] The difference between Comparative Example 2 and Example 1 is the proportion of the all-solid electrolyte raw materials. Specifically:

[0074] By weight, it contains 20 parts of inorganic filler (LLZTO), 10 parts of plasticizer (N-methylacetamide), 10 parts of lithium salt (LiTFSI), 2.4 parts of crosslinking agent (glycerol triglycidyl ether), and 17.6 parts of chain extender (poly(dimethylsiloxane) bis(3-aminopropyl) capped).

[0075] Comparative Example 3

[0076] The difference between Comparative Example 3 and Example 1 is that no inorganic filler was added to the all-solid electrolyte.

[0077] Comparative Example 4

[0078] The difference between Comparative Example 4 and Example 1 is the proportion of the all-solid electrolyte raw materials. Specifically:

[0079] By weight, 80 parts inorganic filler (LLZTO), 3 parts plasticizer (N-methylacetamide), 10 parts lithium salt (LiTFSI), 8 parts crosslinking agent (glycerol triglycidyl ether), and 3 parts chain extender (poly(dimethylsiloxane) bis(3-aminopropyl) capped).

[0080] The ionic conductivity of the composite electrolyte membranes prepared in the above examples and comparative examples was tested, and the results are shown in Table 1.

[0081] Table 1

[0082]

[0083]

[0084] The composite electrolyte membranes prepared in the above examples and comparative examples were used to assemble coin cells, and their initial discharge capacity, discharge capacity after 100 cycles, and average coulombic efficiency were tested and calculated. The results are shown in Table 2. The positive electrode of the coin cell includes: an aluminum foil current collector, and a positive electrode active material layer located on one side of the aluminum foil current collector. In the positive electrode active material layer, the weight ratio of lithium iron phosphate (LiFePO4), conductive agent (acetylene black), and binder (PVDF) is 8:1:1. The negative electrode of the coin cell is a lithium metal sheet, and the composite electrolyte membrane is located between the positive and negative electrodes. The assembled coin cell is of type CR2025. The test conditions for the initial discharge capacity and the discharge capacity after 100 cycles are: room temperature (25°C) at a rate of 0.2C.

[0085] Table 2

[0086]

[0087] The composite electrolyte membranes prepared in the above examples and comparative examples were used to assemble Li / / Li symmetrical coin cells, and their polarization voltages before and after 200 hours of cycling were tested. The results are shown in Table 2. In the Li / / Li symmetrical coin cells, the positive and negative electrodes were 13mm diameter lithium metal sheets, and the composite electrolyte membrane was located between the positive and negative electrodes, resulting in a CR2025 type Li / / Li symmetrical coin cell. The polarization voltage was tested under the following conditions: at 0.1 mA·cm⁻¹. -2At a current density of 1 hour per charge / discharge cycle, a charge / discharge test was performed.

[0088] Table 3

[0089]

[0090] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0091] In Examples 1 to 11, composite solid electrolyte membranes were prepared using the composite solid electrolyte formulation provided in this application. According to Table 1, the composite electrolyte membranes corresponding to the above examples all exhibit excellent conductivity. The composite solid electrolyte membranes corresponding to the above examples were used to prepare coin cells, and their electrochemical performance was tested. The results are shown in Table 2. According to Table 2, the coin cells corresponding to Examples 1 to 11 exhibit excellent battery capacity and cycle stability. Furthermore, the composite solid electrolyte membranes corresponding to the above examples were used to prepare Li / / Li symmetrical coin cells, and their polarization voltage before and after 200 hours of cycling was tested. The results are shown in Table 3. According to Table 3, the initial polarization voltage and the polarization voltage after 200 hours of cycling of the Li / / Li symmetrical coin cells corresponding to Examples 1 to 11 are both within a low range, indicating that the corresponding symmetrical coin cells have excellent operating efficiency. In particular, by controlling the various parameters in the composite solid electrolyte formulation within the preferred range, the conductivity of the composite electrolyte membrane, the coin cell, and the overall electrochemical performance of the Li / / Li symmetrical coin cell are better, resulting in better performance.

[0092] Regarding the above test parameters, the relevant results were plotted using Example 1 as an example. Among them, Figure 1 The impedance diagram of the composite solid electrolyte prepared in Example 1 of the present invention is shown; Figure 2 The room temperature cycling performance of the coin cell corresponding to the composite solid electrolyte prepared in Example 1 of the present invention is shown. Figure 3 The accompanying figures illustrate the cycle performance of a Li / / Li symmetric coin cell corresponding to the composite solid electrolyte prepared in Example 1 of this invention. These figures further corroborate the above conclusions, demonstrating the superior performance of the composite solid electrolyte formulation provided in this application in multiple aspects.

[0093] In contrast, in Comparative Examples 1, 2, and 4, the content of inorganic fillers and other components in the corresponding composite solid electrolyte membranes is not within the scope of protection of this application; in Comparative Example 3, no filler was added to the composite solid electrolyte, and the conductivity of the composite solid electrolyte membranes corresponding to the above comparative examples is significantly different from that in the embodiments of this application. The overall electrochemical performance of the coin cells and Li / / Li symmetric coin cells corresponding to the above comparative examples is also significantly different from that in the embodiments of this application.

[0094] In summary, the composite solid-state electrolyte formulation in this application, through the complex interactions among components including inorganic fillers, plasticizers, lithium salts, crosslinking agents, and chain extenders, collectively constructs a composite solid-state electrolyte that possesses high ionic conductivity, excellent mechanical properties, and electrochemical stability. This performance optimization of the composite electrolyte effectively solves the problems of large layer thickness, high brittleness, and poor interfacial contact in traditional inorganic solid-state electrolytes, providing strong technical support for the development and commercial application of solid-state batteries.

[0095] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite solid electrolyte, characterized in that, The raw materials of the composite solid electrolyte, by weight, include: inorganic filler: 50-100 parts; plasticizer: 5-15 parts; lithium salt: 5-15 parts; crosslinking agent: 1-5 parts; and chain extender: 5-20 parts.

2. The composite solid electrolyte according to claim 1, characterized in that, The raw materials of the composite solid electrolyte, by weight, include: the inorganic filler: 60-100 parts; the plasticizer: 10-15 parts; the lithium salt: 10-15 parts; the crosslinking agent: 1-5 parts; and the chain extender: 10-20 parts.

3. The composite solid electrolyte according to claim 1, characterized in that, In the raw materials of the composite solid electrolyte, the weight content of the crosslinking agent is 1-5%; And / or, in the raw materials of the composite solid electrolyte, the weight content of the chain extender is 10-20%.

4. The composite solid electrolyte according to any one of claims 1 to 3, characterized in that, The weight ratio of the crosslinking agent to the chain extender is (0.1-0.5):

1.

5. The composite solid electrolyte according to any one of claims 1 to 3, characterized in that, The crosslinking agent is at least one of an alkyl epoxide polymer or an epoxy compound; And / or, the number-average molecular weight of the crosslinking agent is 200 to 2000; And / or, the crosslinking agent is one or more of polyethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, resorcinol diglycidyl ether, glycerol triglycidyl ether, and neopentyl glycol diglycidyl ether.

6. The composite solid electrolyte according to any one of claims 1 to 3, characterized in that, The chain extender is an amine chain extender and / or a polysiloxane chain extender; And / or, the chain extender is one or more of p-phenylenediamine, 1,8-octanediamine, polyoxyethylenediamine, poly(dimethylsiloxane) bis(3-aminopropyl)-terminated and adipamide.

7. The composite solid electrolyte according to any one of claims 1 to 6, characterized in that, The inorganic filler is selected from one or more of LLZTO, LLZO, LAGP, alumina, silicon dioxide, and titanium dioxide; And / or, the plasticizer is selected from one or more of succinic anhydride, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and N-methylacetamide; And / or, the lithium salt is selected from one or more of LiFSI, LiBOB, LiPF6, LiClO4, LiTFSI, LiNO3 and LiDFOB.

8. A method for preparing a composite solid electrolyte according to any one of claims 1 to 7, characterized in that, The preparation method includes the following steps: Inorganic fillers, plasticizers, lithium salts, crosslinking agents, and chain extenders are mixed and then pulverized to obtain a mixture. The composite solid electrolyte is obtained by subjecting the mixture to static pressure curing and heat curing.

9. The method for preparing the composite solid electrolyte according to claim 8, characterized in that, The mixing operation is performed in the glove box; And / or, the static pressure curing temperature is 50–100°C, and the time is 5–30 min; And / or, the heating and curing temperature is 40–100°C, and the time is 1–5 hours; And / or, the static pressure curing pressure is 100-300 MPa.

10. A solid-state lithium battery, characterized in that, The solid-state lithium battery includes the composite solid-state electrolyte according to any one of claims 1 to 7.

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