Solid-state electrolyte and preparation method and application thereof

Abstract

This invention discloses a solid electrolyte, its preparation method, and its application, relating to the field of battery technology. The raw material components of the solid electrolyte include comonomers, lithium salts, and initiators. The comonomers include chain acrylate monomers containing ether bonds and cyclic carbonate monomers. The solid electrolyte provided in this application can solve the technical problems of existing technologies, such as the flammability and leakage hazards of traditional liquid electrolytes, the difficulty in balancing ionic conductivity and flexibility with high interfacial impedance in existing polymer electrolytes, and the complex and inefficient preparation processes.

Description

Technical Field

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

[0002] Lithium-ion batteries are widely used in new energy vehicles and energy storage due to their high energy density and other advantages. However, traditional liquid electrolytes are typically composed of carbonate-based organic solvents mixed with lithium salts, making them highly flammable. They are prone to fires during thermal runaway and leakage, leading to battery failure and posing serious safety hazards. Furthermore, liquid electrolytes have poor compatibility with high-capacity positive and negative electrode materials, resulting in violent interfacial reactions and rapid degradation of cycle performance. In contrast, solid-state batteries offer advantages such as safety, non-flammability, high mechanical and thermal stability, ease of processing, and the ability to achieve higher energy density and cycle performance. Polymer electrolytes, due to their good flexibility and interfacial compatibility, are considered ideal solid-state electrolyte materials to replace liquid electrolytes.

[0003] Solid-state electrolytes are a crucial component of solid-state batteries, and polymer electrolytes are among the most widely used materials. However, existing single-polymer systems struggle to achieve a balance of various performance characteristics. While ether-containing chain acrylate monomers combine the lithium-ion conductivity of ether bonds with the film-forming properties of acrylates, the ionic conductivity of pure acrylate polymers remains relatively low. Cyclic carbonate monomers, despite their high dielectric constant and interfacial stability, suffer from insufficient flexibility in homopolymers, making it difficult to adapt to volume changes during electrode charging and discharging. Furthermore, the high interfacial impedance between traditional polymers and electrode materials limits their application. In terms of manufacturing processes, existing methods often involve the separate addition of components, resulting in complex and inefficient processes. Some existing technologies attempt in-situ copolymerization, but the electrolyte system still contains organic solvent components, retaining the shortcomings of liquid batteries. Alternatively, the polyethylene glycol chain structure used has weak oxidation resistance, making it difficult to match with high-potential cathode materials and easily leading to a polymer-derived organic-based cathode interfacial layer, affecting the cycle stability of solid-state batteries.

[0004] Therefore, it is of great significance to develop a polymer solid electrolyte that combines high ionic conductivity, interface compatibility, and simple preparation process. Summary of the Invention

[0005] This invention provides a solid electrolyte, a solid battery, and a method for preparing the same, in order to solve the technical problems of existing liquid electrolytes being flammable and prone to leakage, posing safety hazards; existing solid electrolytes having difficulty in balancing ionic conductivity and flexibility, high interfacial impedance, and complex and inefficient preparation processes.

[0006] The applicant discovered that in-situ copolymerization using ether-bonded chain acrylate monomers and cyclic carbonate monomers as comonomers can simultaneously introduce the lithium-ion conductivity of ether bonds and the high dielectric constant and interfacial stability of cyclic carbonates into the polymer network backbone. In particular, when the cyclic carbonate monomers exist in the copolymer backbone in a chemically bonded form and maintain a specific weight ratio with the ether-bonded chain acrylate monomers, the ionic conductivity, flexibility, and high-voltage resistance of the electrolyte can be synergistically improved. Furthermore, copolymerization using a method of co-implanting lithium salts, monomers, and initiators allows the electrolyte to form in situ inside the battery, simplifying the process and reducing interfacial impedance.

[0007] In a first aspect, the present invention provides a solid electrolyte, wherein the raw material components of the solid electrolyte include a comonomer, a lithium salt and an initiator, wherein the comonomer includes chain acrylate monomers containing ether bonds and cyclic carbonate monomers.

[0008] In some embodiments, the mass ratio of the ether-containing chain acrylate monomer to the cyclic carbonate monomer is (50-80):(20-50).

[0009] In some embodiments, the amount of lithium salt used is 8%-15% of the total mass of the ether-linked chain acrylate monomer and the cyclic carbonate monomer.

[0010] In some embodiments, the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, and lithium bis(fluorosulfonyl)imide.

[0011] In some embodiments, the amount of the initiator is 0.5%-3% of the total mass of the ether-linked chain acrylate monomer and the cyclic carbonate monomer.

[0012] In some embodiments, the initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide.

[0013] In some embodiments, the ether-containing chain acrylate monomer is selected from at least one of ethoxyethoxyethyl acrylate, 3-ethoxyethyl acrylate, 2-phenoxyethyl acrylate, tetrahydrofuran acrylate, and triethylene glycol monomethyl ether acrylate.

[0014] In some embodiments, the cyclic carbonate monomer is selected from at least one of ethylene carbonate and vinylene carbonate.

[0015] Secondly, the present invention provides a method for preparing the above-mentioned solid electrolyte, comprising: mixing a comonomer, a lithium salt and an initiator, and then polymerizing them to obtain a solid electrolyte.

[0016] Thirdly, the present invention provides a solid-state battery, comprising a positive electrode, a negative electrode, and an electrolyte located between the positive electrode and the negative electrode; the electrolyte comprises the aforementioned solid-state electrolyte.

[0017] In some embodiments, the positive electrode comprises at least one of layered ternary materials and lithium iron phosphate.

[0018] In some embodiments, the negative electrode sheet includes at least one of graphite, silicon-carbon material, and silicon-oxygen material.

[0019] Fourthly, the present invention provides a method for preparing the above-mentioned solid-state battery, comprising: Under inert gas protection, the comonomer, lithium salt and initiator are mixed evenly to obtain the electrolyte precursor; The electrolyte precursor is injected into the battery. The battery after the electrolyte precursor is injected is heated to cause the monomers to undergo an in-situ copolymerization reaction inside the battery, thus obtaining the solid-state battery.

[0020] In some embodiments, the temperature of the heat treatment is 50°C-80°C.

[0021] In some embodiments, the heat treatment time is 4h-24h.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Improved safety: The solid electrolyte provided by this invention is a non-flammable substance with a thermal decomposition temperature >200℃, avoiding the problems of flammability and leakage of traditional liquid electrolytes. 2. Excellent ion conductivity: The solid electrolyte provided by this invention has an ion conductivity of up to 10 at room temperature. -4 -10 -3 The S / cm ratio meets the requirements for normal battery operation. 3. Excellent interface compatibility: Although the interface impedance between the solid electrolyte and the NCM811 cathode provided by this invention increases by about 50Ω compared to the liquid electrolyte, the effect of the comonomer is beneficial to improving the battery cycle performance. 4. Excellent flexibility: The solid electrolyte provided by this invention has an elongation at break of >200%, which can adapt to volume changes during electrode charging and discharging.

[0023] 5. Simple preparation process: This invention simplifies the operation process, improves production efficiency, and is easy to industrialize by injecting lithium salt, comonomer and initiator together for copolymerization. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart illustrating the fabrication process of a solid-state battery provided in an embodiment of this application. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0027] Lithium-ion batteries, with their high energy density and long cycle life, have become the mainstream power source in consumer electronics, new energy vehicles, and energy storage. However, traditional commercial lithium-ion batteries generally use liquid electrolytes, which are mainly composed of carbonate-based organic solvents mixed with lithium salts. This liquid system has inherent safety hazards: the organic solvents are highly flammable and can easily cause fires or even explosions in the event of battery thermal runaway; moreover, liquid electrolytes are prone to leakage, leading to battery failure. In addition, liquid electrolytes have poor compatibility with high-capacity positive and negative electrode materials (such as high-nickel ternary and silicon-carbon anodes), resulting in severe interfacial side reactions, which increase interfacial impedance during cycling and cause rapid battery performance degradation.

[0028] To address the aforementioned safety concerns, polymer solid electrolytes, due to their excellent flexibility and interfacial compatibility, are considered ideal alternatives to liquid electrolytes. However, existing single polymer electrolyte systems suffer from performance bottlenecks: while pure acrylate polymers exhibit good film-forming properties and high mechanical strength, their ionic conductivity is relatively low; and while cyclic carbonate homopolymers possess excellent electrochemical stability and high dielectric constants, their flexibility is insufficient to accommodate the volume changes of electrode materials during charge and discharge. Furthermore, the high interfacial impedance between traditional polymer electrolytes and electrode materials limits their application in high-energy-density batteries.

[0029] To balance ionic conductivity and mechanical properties, existing technologies attempt to improve electrolyte performance through copolymerization modification. For example: Chinese patent application CN120149523A discloses a method for preparing solid polymer electrolytes through in-situ copolymerization of electron donor monomers and electron acceptor monomers. This technology uses cyclic ether and olefin monomers as electron donors and cyclic ester and anhydride monomers as electron acceptors. The monomers, electrolyte salts, and initiators are mixed to form a precursor solution before in-situ polymerization. However, the electrolyte system in this technology still contains a significant amount of organic solvent components, failing to fundamentally eliminate the safety hazards of liquid batteries, and solvent residues may affect long-term cycle stability.

[0030] Chinese patent application CN107492680A discloses a vinylene carbonate (VC) and polyethylene glycol (meth)acrylate-based polymer electrolyte and its preparation method. This technology uses polyethylene glycol (meth)acrylate (a macromolecular monomer containing PEO segments) and vinylene carbonate (VC) monomers to form a polymer matrix through copolymerization. However, the polyethylene glycol (PEO) segments have weak oxidation resistance and a narrow electrochemical window, making it difficult to match with high-voltage cathode materials (such as NCM811) with high operating potentials, resulting in poor battery performance at high voltages.

[0031] In view of this, the present invention provides a solid electrolyte, a solid battery and a method for preparing the same, in order to solve the technical problems in the prior art, such as the safety hazards of traditional liquid electrolytes being flammable and prone to leakage, the difficulty in balancing the ionic conductivity and flexibility of existing polymer electrolytes and their high interfacial impedance, and the complexity and low efficiency of the preparation process.

[0032] In a first aspect, the present invention provides a solid electrolyte. According to an embodiment of the present invention, the raw material components of the solid electrolyte include a comonomer, a lithium salt and an initiator, wherein the comonomer includes chain acrylate monomers containing ether bonds and cyclic carbonate monomers.

[0033] The solid electrolyte provided by this invention employs a copolymerization system of ether-linked chain acrylate monomers and cyclic carbonate monomers. The short ether chain structure possesses excellent segmental flexibility and ion conductivity, optimizing the system's wettability; while the rigid ring structure of the cyclic carbonate enhances the molecular skeleton's strength and structural stability. This copolymerization achieves structural complementarity at the molecular level. Through precise control of segmental flexibility and rigidity, it balances interfacial compatibility and mechanical strength, while simultaneously optimizing ion transport pathways and suppressing side reactions, thereby synergistically improving the stability, mechanical properties, and cycle life of the solid electrolyte.

[0034] Specifically, in chain-like acrylate monomers containing ether bonds, the ether bonds can construct continuous lithium-ion transport channels, reducing ion migration resistance and thus improving the ionic conductivity and migration efficiency of solid-state electrolytes. Simultaneously, the acrylate groups in this monomer possess excellent cross-linking film-forming properties, enabling the formation of a dense and stable cross-linked network structure, enhancing the overall mechanical strength and dimensional stability of the electrolyte. Furthermore, this monomer can optimize electrode interface adhesion, suppress interfacial side reactions and volume deformation, and improve interfacial compatibility, thereby effectively enhancing the cycle stability and safety of solid-state electrolytes.

[0035] As a copolymer component, the cyclic carbonate monomer possesses a high dielectric constant, which enhances lithium salt dissociation efficiency, increases the number of free lithium ions in the system, and improves the ion conductivity of the solid electrolyte. Simultaneously, this monomer exhibits excellent interfacial stability, forming a stable passivation layer on the electrode surface and suppressing electrolyte decomposition and interfacial side reactions. Furthermore, the synergistic effect of the cyclic carbonate monomer and the polymer crosslinking system effectively alleviates the volume expansion problem of the electrode during cycling, optimizes the solid-solid interface adhesion between the electrolyte and the electrode, comprehensively improves the interfacial compatibility of the electrolyte, and ensures long-term stable cycling operation of the battery.

[0036] In summary, the copolymerization of ether-containing chain acrylate monomers and cyclic carbonate monomers to form a unified polymer matrix overcomes the inherent defects of single components in terms of ionic conductivity, mechanical flexibility, and interfacial compatibility. This collaborative development has resulted in a high-performance electrolyte alternative material that combines high safety, high ionic conductivity, and excellent interfacial stability, effectively solving the technical problems of flammability and leakage of traditional liquid electrolytes and the insufficient performance of existing solid electrolytes.

[0037] In some embodiments of the present invention, the mass ratio of the ether-containing chain acrylate monomer to the cyclic carbonate monomer is (50-80):(20-50). By limiting the mass ratio of the ether-containing chain acrylate monomer to the cyclic carbonate monomer within the above range, the ether-containing chain acrylate monomer can fully utilize its advantages of high dielectric constant, ion conductivity, and interfacial compatibility, ensuring the efficiency of electrolyte ion transport. Simultaneously, an appropriate amount of cyclic carbonate monomer can fully utilize its rigid structure, effectively reinforcing the strength and heat resistance of the polymer skeleton. Through the above-mentioned reasonable ratio, a balance between flexible segments and rigid cyclic structures can be achieved, avoiding the problems of weak mechanical properties and hindered ion migration caused by an excessively high proportion of a single monomer. This synergistically optimizes the density of the polymer crosslinking network, reduces interfacial impedance, and balances the conductivity, mechanical strength, and long-term interfacial stability of the solid electrolyte.

[0038] In some embodiments of the present invention, the ether-containing chain acrylate monomers are selected from at least one of ethoxyethyl acrylate (DEGEEA), 3-ethoxyethyl acrylate (3-EEA), 2-phenoxyethyl acrylate (PHEA), tetrahydrofuran acrylate (THFA), and triethylene glycol monomethyl ether acrylate (TEGMA). The ether-containing chain acrylate monomers selected from the above range have molecular chains rich in flexible ether bond structures, which can construct continuous lithium-ion transport pathways, improving the lithium salt dissociation ability and ionic conductivity. Simultaneously, the molecular side chain structure can optimize the polymer crosslinking arrangement, reduce the cohesive energy of the system, and improve the flexibility of the solid electrolyte. Furthermore, these monomers exhibit excellent chemical inertness, forming a stable interfacial film on the electrode surface, suppressing interfacial side reactions, and synergistically improving the mechanical properties, interfacial compatibility, and cycle stability of the composite electrolyte.

[0039] The structural formulas of DEGEEA, 3-EEA, PHEA, and THFA are as follows:

[0040] In some embodiments of the present invention, the cyclic carbonate monomer is selected from at least one of ethylene ethylene carbonate (VEC) and ethylene carbonate (VC). Cyclic carbonate monomers selected from the above range possess a highly polar cyclic carbonate structure, which is beneficial for improving the dielectric constant of the system and promoting the complete dissociation of lithium salts. The rigid cyclic framework can enhance the structural strength and dimensional stability of the polymer crosslinking network, alleviating deformation problems during cycling. Simultaneously, these monomers can preferentially passivate and form a film on the electrode surface, constructing a dense and stable interfacial protective layer, suppressing side reactions between the electrode and electrolyte, optimizing solid-solid interface contact, and synergistically improving the oxidation resistance and long-cycle stability of the solid electrolyte.

[0041] In some embodiments of the present invention, the amount of lithium salt is 8%-15% of the total mass of the ether-bonded chain acrylate monomers and the cyclic carbonate monomers. Limiting the amount of lithium salt within this range achieves a balance between lithium salt dissociation and ion transport. An appropriate amount of lithium salt can adequately replenish free lithium ions, improve the conduction pathway, and effectively enhance the ionic conductivity of the solid electrolyte; too low a lithium salt content can lead to insufficient charge carriers and weak conductivity. Too high a content can cause ion aggregation, increase system viscosity, hinder chain segment movement, reduce the density of the crosslinked network, and increase interfacial impedance. This formulation avoids the above-mentioned defects, balancing the mechanical structural stability of the electrolyte with lithium ion migration efficiency.

[0042] There are no special limitations on the type of lithium salt. Those skilled in the art can make flexible choices as needed. The lithium salts mentioned in this application include, but are not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium bis(fluorosulfonyl)imide (LiFSI).

[0043] In some embodiments of the present invention, the amount of initiator is 0.5%-3% of the total mass of the ether-containing chain acrylate monomers and the cyclic carbonate monomers. Limiting the amount of initiator within this range allows for the control of the polymerization and crosslinking reaction rate and crosslinking density of the acrylate monomers. An appropriate amount of initiator ensures complete polymerization of the monomers, forming a uniform and dense crosslinked network, thus guaranteeing the overall structural stability of the solid electrolyte. Too low an initiator content leads to incomplete polymerization, a loose network structure, and decreased mechanical properties. Too high an amount easily generates excessive free radical side reactions, resulting in over-crosslinking, increased system brittleness, and residual small molecules that deteriorate interfacial properties. This ratio balances the degree of polymerization and film-forming quality, stabilizing electrochemical performance.

[0044] In some embodiments of the present invention, the initiator is selected from at least one of azobisisobutyronitrile (AIBN), azobisisoheptanenitrile (ABVN), and benzoyl peroxide (BPO).

[0045] Secondly, the present invention provides a method for preparing the above-mentioned solid electrolyte, which, according to an embodiment of the present application, includes: mixing a comonomer, a lithium salt and an initiator, and then polymerizing them to obtain a solid electrolyte.

[0046] The solid electrolyte preparation method provided by this invention adopts a process route in which ether-linked chain acrylate monomers, cyclic carbonate monomers, lithium salts and initiators are mixed uniformly in one step and then directly polymerized. This process differs from the complex process of adding each component separately in the traditional method, simplifying the operation steps and improving production efficiency. This all-component premixing method ensures the uniform distribution of lithium salts and comonomers, avoiding uneven polymerization caused by local concentration differences. At the same time, the fluidity of the electrolyte precursor allows it to fully wet the micropores of the electrode material, forming a solid electrolyte network in situ during the subsequent polymerization process. This achieves a tight fit between the electrolyte and the electrode interface, effectively reducing interfacial contact resistance. Furthermore, the process is highly controllable, which is conducive to ensuring the consistency between product batches. This provides a convenient, efficient and low-cost technical solution for the large-scale manufacturing of high-performance solid-state batteries.

[0047] Thirdly, the present invention provides a solid-state battery. According to an embodiment of this application, the solid-state battery includes a positive electrode, a negative electrode, and an electrolyte located between the positive electrode and the negative electrode; the electrolyte includes the solid electrolyte described above.

[0048] The solid-state battery provided by this invention uses a solid electrolyte formed by copolymerization of the aforementioned specific components, which can solve the safety problems of flammability and leakage of traditional liquid electrolytes and improve the thermal stability and safety of the battery. This is because the synergistic effect of the ether-linked chain acrylate and cyclic carbonate structure in the electrolyte constructs an ion transport network with both high ionic conductivity and excellent flexibility inside the battery, effectively reducing interfacial impedance and suppressing oxidative decomposition side reactions under high voltage. At the same time, the electrolyte layer formed by the in-situ polymerization process achieves molecular-level close contact with the positive and negative electrode sheets, which can adapt to the volume changes of the electrode materials during charging and discharging. This allows the battery to maintain excellent cycle stability even in high-energy-density systems (such as high-nickel ternary cathodes / silicon-carbon anodes), thereby improving safety and cycle life.

[0049] Fourthly, the present invention provides a method for preparing the above-mentioned solid-state battery, such as... Figure 1 As shown in the embodiments of this application, the preparation method includes: S100. Under the protection of an inert gas, the comonomer, lithium salt and initiator are mixed evenly to obtain the electrolyte precursor. S200, Inject the electrolyte precursor into the battery; S300. The battery after the electrolyte precursor is injected is heated to cause the monomer to undergo an in-situ copolymerization reaction inside the battery, thereby obtaining the solid-state battery.

[0050] The solid-state battery fabrication method provided by this invention employs a full-component premixing and in-situ polymerization process under inert gas protection. Utilizing the fluidity of the electrolyte precursor to fully wet the micropores of the positive and negative electrode sheets eliminates the defects of poor solid-solid contact between traditional solid electrolytes and electrodes. This constructs a solid electrolyte layer that is molecularly and tightly bonded to the electrode surface in situ within the battery, reducing interfacial contact resistance. This in-situ curing strategy eliminates the need for separate preparation, transfer, and lamination processes of traditional solid electrolyte membranes, simplifying the production process and improving manufacturing efficiency and batch consistency. Simultaneously, the controllable in-situ copolymerization reaction ensures the full conversion of comonomers and the chemical bonding of cyclic carbonate monomers to the polymer backbone. Combined with inert gas protection, side reactions are prevented. The resulting solid-state battery exhibits high intrinsic safety, excellent interfacial stability, and long cycle life, providing a convenient and efficient technical path for the large-scale production of high-performance solid-state batteries.

[0051] The type of inert gas is not specifically limited, and those skilled in the art can choose flexibly as needed. The inert gas in this application includes, but is not limited to, nitrogen or argon. Specifically, monomer A, monomer B, lithium salt and initiator are added to a reaction vessel, stirred evenly to fully dissolve the lithium salt, and then inert gas such as nitrogen or argon is introduced for 10-30 minutes to remove oxygen from the system, forming a copolymer electrolyte precursor.

[0052] In some embodiments of the present invention, the heat treatment temperature is 50°C-80°C. Limiting the heat treatment temperature within this range allows for gentle control of the polymerization and crosslinking reaction process, promoting complete monomer reaction and orderly crosslinking of molecular chains. This temperature range ensures stable decomposition of the initiator to generate active free radicals, achieving uniform curing and film formation, while avoiding thermal degradation of molecular chains and increased internal micropore defects caused by high temperatures. Simultaneously, it prevents excessively low temperatures from leading to slow reaction rates and incomplete crosslinking and curing, effectively balancing crosslinking efficiency and structural integrity, and ensuring the electrolytic mechanical properties and ion transport stability.

[0053] In some embodiments of the present invention, the heat treatment time is 4-24 hours. Limiting the heat treatment time within this range ensures the gradual polymerization and cross-linking of monomers, promoting full bonding of molecular chains and forming a uniform and dense cross-linked network. Too short a time leads to insufficient polymerization and cross-linking, resulting in a loose electrolyte structure and weak mechanical strength; too long a time can cause excessive aging of molecular chains and excessive local cross-linking, increasing the internal resistance of the system. This time range allows for reasonable and controllable reaction degree, elimination of residual monomers, optimization of microstructure, stabilization of interfacial properties, and a balance between the mechanical properties and ion conductivity of the solid electrolyte.

[0054] The technical solution provided by the present invention will be described in detail below with reference to the embodiments.

[0055] Unless otherwise specified, the raw materials used in the examples and comparative examples are commercially available analytical grade materials.

[0056] Example 1 Example 1 of this application provides a method for preparing a DEGEEA-VEC solid electrolyte E1 and its solid battery B1, as detailed below: Weigh 0.7g of ethoxyethyl acrylate (DEGEEA), 0.3g of ethylene ethylene carbonate (VEC), 0.1g of lithium hexafluorophosphate (LiPF6) and 0.01g of azobisisobutyronitrile (AIBN), add them together to a reaction flask, and stir continuously at room temperature until LiPF6 is completely dissolved to obtain a homogeneous electrolyte precursor.

[0057] The electrolyte precursor was processed in two ways: one was by injecting it into a beaker, and the other was by injecting the electrolyte precursor with NCM811 as the positive electrode, silicon carbon as the negative electrode, and Celgard 2400 as the separator, and assembling it into a CR2032 coin cell in an argon glove box. Subsequently, the samples of both methods were baked at 60°C for 4 hours to allow DEGEEA and VEC to undergo a copolymerization reaction, resulting in a DEGEEA-VEC copolymer solid electrolyte (denoted as E1) and a DEGEEA-VEC copolymer solid electrolyte-based solid silicon carbon / NCM811 battery (denoted as B1).

[0058] Example 2 Example 2 of this application provides a method for preparing a PHEA-VC copolymer solid electrolyte E2 and its solid battery B2, as detailed below: Accurately weigh 0.6 g of 2-phenoxyethyl acrylate (PHEA), 0.4 g of vinylene carbonate (VC), 0.12 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 0.015 g of benzoyl peroxide (BPO), add them together to a reaction flask, and stir continuously at room temperature until LiTFSI is completely dissolved to obtain a homogeneous precursor solution.

[0059] The precursor solution was processed in two ways: one was by injecting it into a beaker, and the other was by injecting the electrolyte precursor with NCM811 as the positive electrode, silicon carbon as the negative electrode, and Celgard 2400 as the separator, and assembling it into a CR2032 coin cell in an argon glove box. Subsequently, the samples of both methods were baked at 70°C for 12 hours to allow PHEA and VC to undergo a copolymerization reaction, resulting in PHEA-VC copolymer solid electrolyte (denoted as E2) and PHEA-VC copolymer solid electrolyte-based solid silicon carbon / NCM811 battery (denoted as B2).

[0060] Example 3 Example 3 of this application provides a method for preparing a THFA-VEC copolymer solid electrolyte E3 and its solid battery B3, as detailed below: Accurately weigh 0.6 g tetrahydrofuran acrylate (THFA), 0.5 g ethylene ethylene carbonate (VEC), 0.08 g lithium hexafluorophosphate (LiPF6) and 0.02 g azobisisoheptanenitrile (ABVN), add them together to a reaction flask, and stir continuously at room temperature until LiPF6 is completely dissolved to obtain a homogeneous precursor solution.

[0061] The precursor solution was treated in two ways: one was by injecting it into a beaker, and the other was by injecting the electrolyte precursor with NCM811 as the positive electrode, silicon carbon as the negative electrode, and Celgard 2400 as the separator, and assembling it into a CR2032 coin cell in an argon glove box. Subsequently, the samples of both treatments were baked at 80°C for 24 hours to allow THFA and VEC to undergo a copolymerization reaction, resulting in a THFA-VEC copolymer solid electrolyte (denoted as E3) and a THFA-VEC copolymer solid electrolyte-based solid silicon carbon / NCM811 battery (denoted as B3).

[0062] Example 4 Example 4 of this application provides a method for preparing a DEGEEA-VEC copolymer solid electrolyte E4 and its solid battery B4, as detailed below: Weigh 0.5g of ethoxyethyl acrylate (DEGEEA), 0.5g of ethylene ethylene carbonate (VEC), 0.08g of lithium hexafluorophosphate (LiPF6) and 0.005g of azobisisobutyronitrile (AIBN), add them together to a reaction flask, and stir continuously at room temperature until LiPF6 is completely dissolved to obtain a homogeneous precursor solution.

[0063] The precursor solution was processed in two ways: one was by injecting it into a beaker, and the other was by injecting the electrolyte precursor with NCM811 as the positive electrode, silicon carbon as the negative electrode, and Celgard 2400 as the separator, and assembling it into a CR2032 coin cell in an argon glove box. Subsequently, the samples of both methods were baked at 60°C for 4 hours to allow DEGEEA and VEC to undergo a copolymerization reaction, resulting in a DEGEEA-VEC copolymer solid electrolyte (denoted as E4) and a DEGEEA-VEC copolymer solid electrolyte-based solid silicon carbon / NCM811 battery (denoted as B4).

[0064] Example 5 Example 5 of this application provides a method for preparing a DEGEEA-VEC copolymer solid electrolyte E5 and its solid battery B5, as detailed below: Weigh 0.8g of ethoxyethyl acrylate (DEGEEA), 0.2g of ethylene ethylene carbonate (VEC), 0.15g of lithium hexafluorophosphate (LiPF6) and 0.03g of azobisisobutyronitrile (AIBN), add them together to a reaction flask, and stir continuously at room temperature until LiPF6 is completely dissolved to obtain a homogeneous precursor solution.

[0065] The precursor solution was processed in two ways: one was by injecting it into a beaker, and the other was by injecting the electrolyte precursor with NCM811 as the positive electrode, silicon carbon as the negative electrode, and Celgard 2400 as the separator, and assembling it into a CR2032 coin cell in an argon glove box. Subsequently, the samples of both methods were baked at 60°C for 4 hours to allow DEGEEA and VEC to undergo a copolymerization reaction, resulting in a DEGEEA-VEC copolymer solid electrolyte (denoted as E5) and a DEGEEA-VEC copolymer solid electrolyte-based solid silicon carbon / NCM811 battery (denoted as B5).

[0066] Example 6 Example 6 of this application provides a method for preparing a DEGEEA-VEC copolymer solid electrolyte E6 and its solid battery B6, as detailed below: Weigh 0.25g of ethoxyethyl acrylate (DEGEEA), 0.5g of ethylene ethylene carbonate (VEC), 0.15g of lithium hexafluorophosphate (LiPF6) and 0.03g of azobisisobutyronitrile (AIBN), add them together to a reaction flask, and stir continuously at room temperature until LiPF6 is completely dissolved to obtain a homogeneous precursor solution.

[0067] The precursor solution was processed in two ways: one was by injecting it into a beaker, and the other was by injecting the electrolyte precursor with NCM811 as the positive electrode, silicon carbon as the negative electrode, and Celgard 2400 as the separator, and assembling it into a CR2032 coin cell in an argon glove box. Subsequently, the samples of both methods were baked at 60°C for 4 hours to allow DEGEEA and VEC to undergo a copolymerization reaction, resulting in a DEGEEA-VEC copolymer solid electrolyte (denoted as E6) and a DEGEEA-VEC copolymer solid electrolyte-based solid silicon carbon / NCM811 battery (denoted as B6).

[0068] Example 7 Example 7 of this application provides a method for preparing a DEGEEA-VEC copolymer solid electrolyte E7 and its solid battery B7, as detailed below: Weigh 0.9g of ethoxyethyl acrylate (DEGEEA), 0.2g of ethylene ethylene carbonate (VEC), 0.15g of lithium hexafluorophosphate (LiPF6) and 0.03g of azobisisobutyronitrile (AIBN), add them together to a reaction flask, and stir continuously at room temperature until LiPF6 is completely dissolved to obtain a homogeneous precursor solution.

[0069] The precursor solution was processed in two ways: one was by injecting it into a beaker, and the other was by injecting the electrolyte precursor with NCM811 as the positive electrode, silicon carbon as the negative electrode, and Celgard 2400 as the separator, and assembling it into a CR2032 coin cell in an argon glove box. Subsequently, the samples of both methods were baked at 60°C for 4 hours to allow DEGEEA and VEC to undergo a copolymerization reaction, resulting in a DEGEEA-VEC copolymer solid electrolyte (denoted as E7) and a DEGEEA-VEC copolymer solid electrolyte-based solid silicon carbon / NCM811 battery (denoted as B7).

[0070] Comparative Example 1 Comparative Example 1 provides a method for preparing a silicon-carbon / NCM811 battery using a conventional liquid electrolyte, as detailed below: Traditional liquid electrolyte preparation: Ethylene carbonate (EC) and dimethyl carbonate (DMC) are used as organic solvents and mixed evenly at a volume ratio of 1:1. Lithium hexafluorophosphate (LiPF6) is then added to the mixed organic solvent and stirred until completely dissolved to prepare a LiPF6-EC / DMC mixed liquid electrolyte (denoted as SD) with a concentration of 1 mol / L.

[0071] Using NCM811 as the positive electrode, silicon-carbon as the negative electrode, and Celgard 2400 as the separator, the above liquid electrolyte was injected and assembled into a CR2032 coin cell in an argon glove box to obtain a silicon-carbon / NCM811 battery. The resulting battery is denoted as sample CE.

[0072] Comparative Example 2 Comparative Example 2 provides a method for preparing a VEC homopolymer solid electrolyte E8 and its solid-state battery B8, as detailed below: Accurately weigh 1g of ethylene ethylene carbonate (VEC), 0.1g of lithium hexafluorophosphate (LiPF6), and 0.01g of azobisisobutyronitrile (AIBN), add them together to a reaction flask, and stir continuously at room temperature until LiPF6 is completely dissolved to obtain a homogeneous precursor solution.

[0073] The precursor solution was processed in two ways: one was by injecting it into a beaker, and the other was by injecting the electrolyte precursor with NCM811 as the positive electrode, silicon carbon as the negative electrode, and Celgard 2400 as the separator, and assembling it into a CR2032 coin cell in an argon glove box. Subsequently, the samples of both methods were baked at 60°C for 4 hours to induce homopolymerization, resulting in VEC homopolymer solid electrolyte (denoted as E8) and VEC homopolymer solid electrolyte-based solid silicon carbon / NCM811 battery (denoted as B8).

[0074] Comparative Example 3 Comparative Example 3 provides a method for preparing a DEGEEA solid electrolyte E9 and its solid battery B9, as detailed below: Weigh 1g of ethoxyethoxyethyl acrylate (DEGEEA), 0.1g of lithium hexafluorophosphate (LiPF6) and 0.01g of azobisisobutyronitrile (AIBN), add them together to a reaction flask, and stir continuously at room temperature until LiPF6 is completely dissolved to obtain a homogeneous precursor solution.

[0075] The precursor solution was processed in two ways: one was by injecting it into a beaker, and the other was by injecting the electrolyte precursor with NCM811 as the positive electrode, silicon carbon as the negative electrode, and Celgard 2400 as the separator, and assembling it into a CR2032 coin cell in an argon glove box. Subsequently, the samples of both methods were baked at 60°C for 4 hours to induce homopolymerization, resulting in DEGEEA homopolymer solid electrolyte (denoted as E9) and DEGEEA homopolymer solid electrolyte-based solid silicon carbon / NCM811 battery (denoted as B9).

[0076] Comparative Example 4 Comparative Example 4 provides a method for preparing a gel electrolyte E10 and a solid-state battery B10 by in-situ solidification of a conventional electrolyte SD and VEC, as detailed below: Accurately weigh 1g of ethylene ethylene carbonate (VEC) and 0.01g of azobisisobutyronitrile (AIBN), and measure 20g of conventional liquid electrolyte SD (the same 1mol / L LiPF6-EC / DMC mixed liquid electrolyte prepared in Comparative Example 1). Add them together to the reaction flask and stir continuously at room temperature until the system is completely clear to obtain a homogeneous precursor solution.

[0077] The precursor solution was processed in two ways: one was by injecting it into a beaker, and the other was by injecting the electrolyte precursor with NCM811 as the positive electrode, silicon carbon as the negative electrode, and Celgard 2400 as the separator, and assembling it into a CR2032 coin cell in an argon glove box. Subsequently, the samples of both methods were baked at 60°C for 4 hours to allow VEC and the traditional electrolyte SD to form a gel system through in-situ solidification reaction, resulting in a gel electrolyte (denoted as E10) and a gel solid silicon carbon / NCM811 battery (denoted as B10).

[0078] Performance testing 1. The room temperature ionic conductivity, thermal decomposition temperature, flammability, and elongation at break of the electrolytes of Examples 1-7 and Comparative Examples 1-4 were tested. The specific test methods and procedures are as follows: 1) Room temperature ionic conductivity test: Under room temperature (25℃) conditions, with a frequency range of 1Hz-1MHz and an amplitude of 5mV, AC impedance testing was performed on the symmetrical cell, and the impedance spectrum was recorded. The ionic conductivity was calculated according to the formula σ= L / (Rb×S), where σ is the ionic conductivity (S / cm), L is the electrolyte thickness (cm), Rb is the resistance value (Ω) at the intersection of the arc and the real axis in the impedance spectrum, and S is the electrode area (cm²).

[0079] 2) Thermal decomposition temperature: Approximately 5 mg of each electrolyte was placed in an alumina crucible. Under a nitrogen atmosphere, the heating rate was set to 10 °C / min, and the temperature range was from room temperature to 500 °C. The mass change curve of the sample as a function of temperature was recorded. The thermal decomposition temperature was defined as the temperature at which the sample mass decreased by 5%. For liquid electrolytes (SD), the boiling temperature was recorded.

[0080] 3) Combustion test: Take 2 mL of each electrolyte into a ceramic crucible, heat the bottom of the crucible with an alcohol torch, observe whether the sample burns and the intensity of the burning, and record the burning phenomenon.

[0081] 4) Elongation at break test: Each electrolyte is made into a dumbbell-shaped sample with a thickness of 0.2 mm, a length of 50 mm, and a width of 10 mm. Traditional liquid electrolyte (SD) cannot form a film, so this test is not performed. Under room temperature conditions, the tensile rate is set to 50 mm / min, and the two ends of the sample are clamped for tensile testing. The elongation at break is recorded. Elongation at break = (elongation at break / initial length) × 100%.

[0082] The test results are shown in Table 1: Table 1 Electrolyte performance test results

[0083] " / " indicates no.

[0084] As can be seen from the data in Table 1, the data from Examples 1-5 and Examples 6-7 show that reasonable control of monomer ratio and component dosage can effectively improve the ionic conductivity and mechanical flexibility of electrolytes. Compared with the optimal ratio range of Examples 1-5, after deviating from this range, the elongation at break and ionic conductivity of electrolytes decreased significantly, and the overall performance of materials deteriorated significantly. As can be seen from the data of Examples 1-7 and Comparative Example 1, the solid electrolyte prepared by the present invention has a slightly lower room temperature ionic conductivity, but a significantly higher thermal decomposition temperature, and fully possesses flame-retardant and non-flammable properties, effectively improving the defects of traditional liquid electrolytes that are extremely prone to violent combustion and have extremely poor thermal stability. As can be seen from the data of Examples 1-7 and Comparative Example 2, the copolymer modification system of the present invention can improve ion transport efficiency and significantly enhance the tensile toughness of the material. While maintaining excellent flame retardant and heat-resistant properties, it achieves a synergistic improvement in mechanical and electrical properties. As can be seen from the data of Examples 1-7 and Comparative Example 3, the formulation system of the present invention can effectively improve the lithium salt dissociation efficiency and ion migration rate, obtain better ionic conductivity, and take into account both heat resistance and structural flexibility, with significant comprehensive performance advantages. As can be seen from the data of Examples 1-7 and Comparative Example 4, compared with conventional electrolytes with high flammability, the copolymer curing system of the present invention has significantly enhanced thermal decomposition resistance and excellent flame retardant effect, which can effectively avoid the risk of battery thermal runaway combustion. The above results demonstrate that the present invention, through copolymerization modification of ether-chain acrylates and cyclic carbonate monomers, combined with appropriate amounts of lithium salts, initiators, and preparation processes, can synergistically optimize the ion conductivity, mechanical toughness, thermal stability, and flame retardant safety performance of solid electrolytes. The components complement each other and have complementary advantages, which is conducive to improving the overall application performance of the electrolyte and meeting the needs of high-safety energy storage batteries.

[0085] 2. The cycle performance and interface impedance of the batteries in Examples 1-7 and Comparative Examples 1-4 were tested. The specific test procedures are as follows: 1) Battery cycle performance test Test conditions: 25℃, 0.5C charge / discharge, voltage range 3.0-4.3V. Test procedure: Charge the battery with a constant current to 4.3V, let it rest for 5 minutes, then discharge it with a constant current to 3.0V, and let it rest for 5 minutes to complete one charge-discharge cycle. Record the discharge capacity of each cycle and calculate the capacity retention rate. Capacity retention rate = (discharge capacity of the nth cycle / discharge capacity of the 1st cycle) × 100%.

[0086] The test results are shown in Table 2: Table 2 Cyclic performance results

[0087] As can be seen from the data in Table 2, the data from Examples 1-5 and Examples 6-7 show that the copolymer system with optimized monomer types and ratios can effectively improve the battery cycle capacity retention rate and the capacity decay rate is more gradual during long-term cycling. Compared with the optimized ratios in Examples 1-5, the imbalance in the composition ratio will significantly aggravate the capacity decay and reduce the cycle stability. As can be seen from the data of Examples 1-7 and Comparative Example 1, the solid electrolyte of the present invention can effectively reduce capacity loss during cycling, and has higher capacity retention rate under 50, 100 and 200 long-cycle cycles, and its cycle durability performance is better than that of the comparative system. As can be seen from the data of Examples 1-7 and Comparative Example 2, the cycle capacity of Comparative Example 2 decayed rapidly and abruptly, while the embodiments of the present invention can maintain stable electrochemical cycle performance, effectively suppress interface degradation and active material loss, and significantly extend cycle life. The data from Examples 1-7 and Comparative Example 3 show that the battery in Comparative Example 3 has a faster cycle failure rate and almost complete capacity decay. The copolymer crosslinking structure of the present invention can stabilize the electrode / electrolyte interface and improve long-cycle service capability. As can be seen from the data of Examples 1-7 and Comparative Example 4, compared with conventional modified electrolytes, the system of the present invention has better interface compatibility, can maintain a stable ion transport environment, and effectively alleviates performance degradation under long-term cycling. The above results demonstrate that the solid electrolyte constructed by copolymerizing ether-bonded acrylates and cyclic carbonates in this invention can build a stable interfacial structure and cross-linking network, effectively suppressing side reactions and structural degradation during cycling, thereby improving the battery's long-term cycle capacity retention and cycle stability, and possessing excellent long-term electrochemical application value.

[0088] 2) Interface impedance test At room temperature (25℃), the frequency range was set to 1Hz-1MHz and the amplitude to 5mV. AC impedance tests were performed on the battery in its initial state and the battery after 100 cycles. The impedance spectrum was recorded, and the charge transfer resistance value corresponding to the semicircle in the impedance spectrum was read, which is the interface impedance.

[0089] The test results are shown in Table 3: Table 3. Interfacial Impedance Test Results

[0090] As can be seen from the data in Table 3, the data from Examples 1-5 and Examples 6-7 show that reasonable selection of monomer types and optimization of ratio can effectively reduce the initial interfacial impedance of the system, and the impedance increase after cycling is small; while when the components are not properly matched, the initial impedance increases significantly, the interfacial impedance increases sharply after long cycling, and the interfacial stability decreases significantly. As can be seen from the data of Examples 1-7 and Comparative Example 1, Comparative Example 1 has a lower initial impedance, but the impedance increase of each embodiment of the present invention is gradual, the interface structure is not easily degraded, and a long-term stable interface transmission environment can be maintained. The data from Examples 1-7 and Comparative Example 2 show that the initial interface impedance of Comparative Example 2 is extremely high. After 100 cycles, the impedance increases dramatically, and the interface deteriorates severely. The system of the present invention can effectively avoid this problem, and the interface evolution is stable and controllable. The data from Examples 1-7 and Comparative Example 3 show that Comparative Example 3 has a large initial impedance and severe interface failure after cycling, with a significant increase in impedance. The copolymer structure of the present invention can optimize solid-solid interface contact and suppress the continuous accumulation of interface side reactions. The data from Examples 1-7 and Comparative Example 4 show that the impedance in Comparative Example 4 decreases abnormally during the cycle, and the interface structure is prone to change. In contrast, the impedance change pattern of the embodiments of the present invention is stable, and the integrity and stability of the interface structure are better. The above results demonstrate that the present invention, through copolymerization modification of ether-chain acrylates and cyclic carbonates, can construct a stable and compatible electrode-electrolyte interface, reasonably control the interface impedance level, suppress interface aging and side reaction accumulation during cycling, ensure stable ion transport, and improve the long-term service performance of the battery from the interface level.

[0091] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0092] It should be noted that in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, technology, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, technology, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, technology, article, or apparatus that includes said element. In this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly specified.

[0093] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A solid electrolyte, characterized in that, The raw material components of the solid electrolyte include comonomers, lithium salts, and initiators. The comonomers include chain acrylate monomers containing ether bonds and cyclic carbonate monomers.

2. The solid-state electrolyte of claim 1, wherein, The mass ratio of the ether-containing chain acrylate monomer to the cyclic carbonate monomer is (50-80):(20-50).

3. The solid-state electrolyte of claim 1, wherein, The amount of lithium salt used is 8%-15% of the total mass of the ether-containing chain acrylate monomers and the cyclic carbonate monomers; and / or, The lithium salt is selected from at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, and lithium bis(fluorosulfonyl)imide.

4. The solid state electrolyte of claim 1, wherein, The amount of the initiator is 0.5%-3% of the total mass of the ether-containing chain acrylate monomers and the cyclic carbonate monomers; and / or, The initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide.

5. The solid state electrolyte of claim 1, wherein, The ether-containing chain acrylate monomers are selected from at least one of ethoxy ethoxy ethyl acrylate, 3-ethoxy ethyl acrylate, 2-phenoxy ethyl acrylate, tetrahydrofuran acrylate, and triethylene glycol monomethyl ether acrylate.

6. The solid electrolyte as described in claim 1, characterized in that, The cyclic carbonate monomers are selected from at least one of ethylene carbonate and vinylene carbonate.

7. A method for preparing a solid electrolyte as described in any one of claims 1-6, characterized in that, include: A solid electrolyte is obtained by mixing comonomers, lithium salts, and initiators and then polymerizing them.

8. A solid-state battery, characterized in that, It includes a positive electrode, a negative electrode, and an electrolyte located between the positive electrode and the negative electrode; the electrolyte includes a solid electrolyte as described in any one of claims 1-6.

9. The solid-state battery as described in claim 8, characterized in that, The positive electrode sheet includes at least one of layered ternary materials and lithium iron phosphate.

10. The solid-state battery as described in claim 8, characterized in that, The negative electrode sheet includes at least one of graphite, silicon-carbon material, and silicon-oxygen material.

11. A method of producing a solid-state battery as claimed in any one of claims 8-10, characterized by, include: Under inert gas protection, the comonomer, lithium salt and initiator are mixed evenly to obtain the electrolyte precursor; The electrolyte precursor is injected into the battery. The battery after the electrolyte precursor is injected is heated to cause the monomers to undergo an in-situ copolymerization reaction inside the battery, thus obtaining the solid-state battery.

12. The preparation method according to claim 11, characterized in that, The temperature of the heat treatment is 50℃-80℃.

13. The production method according to claim 11, wherein The heat treatment time is 4h-24h.

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