A high-temperature-resistant solid-state battery polymer electrolyte composite and a preparation method thereof

Abstract

The application discloses a kind of high-temperature-resistant solid-state battery polymer electrolyte composite and preparation method thereof, belong to solid-state battery material technical field.The preparation step includes: the preparation of key functional component, the preparation of precursor solution, the dispersion and compounding of filler, film casting and heat treatment and post-processing.The application constructs "oxygen-sulfur" coordination network by introducing dynamic sulfide bond into main chain, and solves the problems such as that traditional polymer electrolyte cannot consider ion conductivity and mechanical strength at high temperature, filler is easy to aggregate and film has many defects by combining multi-component interface chemical bonding and gradient curing process.The material obtained still maintains high ion conductivity and excellent mechanical stability at 150 DEG C, and has wide electrochemical window, and is suitable for high safety, high energy density solid-state battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid-state battery materials, and particularly relates to a high-temperature-resistant polymer electrolyte composite material for solid-state batteries and a preparation method thereof. BACKGROUND

[0002] Solid-state batteries use non-flammable solid-state electrolytes to replace liquid electrolytes, which is considered as a key technology path to fundamentally solve the safety problem and is expected to be compatible with high-capacity metal lithium negative electrodes and high-voltage positive electrode materials, and has become the research focus of the next generation of batteries.

[0003] Among various solid-state electrolytes, composite polymer solid-state electrolytes are attracting attention due to their good flexibility, easy processability, high ionic conductivity and mechanical strength of inorganic fillers. However, the existing mainstream system, especially the composite electrolyte with polyethylene oxide (PEO) as the matrix, faces two core bottlenecks: first, the high-temperature resistance is insufficient. The crystalline melting point of PEO is 60-70℃, and when the working temperature exceeds 80℃, the mechanical strength of the matrix will decrease sharply due to softening, which can easily lead to internal short circuit of the battery, and the ionic conductivity will also decrease due to excessive disorder of the chain segment; second, the electrochemical window is narrow, and it is difficult to stably match high-voltage positive electrode materials such as high-nickel ternary and lithium-rich manganese-based materials, which limits the improvement of energy density.

[0004] In order to improve the above-mentioned performances, the existing technology mainly uses copolymerization, blending or adding inorganic fillers for modification. However, these methods often have limitations: copolymerization or blending is difficult to maintain high ionic conductivity while giving the material sufficient high-temperature dimensional stability; simple physical doping of inorganic fillers is easy to agglomerate in the polymer matrix, resulting in poor interfacial compatibility, discontinuous ion transport path, and limited effect on widening the electrochemical window. More importantly, most improvement schemes often sacrifice other performances when improving a certain performance, and it is difficult to achieve a balance of comprehensive performance at high temperature.

[0005] Therefore, it is of urgent need and great significance to develop a composite polymer electrolyte material that can simultaneously have excellent mechanical strength, high ionic conductivity, wide electrochemical window and good interfacial stability in a wide temperature range (especially in the high-temperature range of 80-150℃) for promoting the practical application of high-safety and high-energy-density solid-state batteries. SUMMARY

[0006] The purpose of the present application is to solve the problems existing in the prior art, and to provide a preparation method of a high-temperature-resistant polymer electrolyte composite material for solid-state batteries and its application.

[0007] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0008] The application provides a preparation method of a high-temperature-resistant solid-state battery polymer electrolyte composite, which comprises the following steps:

[0009] S1: preparation of a key functional component:

[0010] S101: 1,4-hydroquinone, 4,4'-dichlorodiphenyl sulfone, 4,4'-dimercaptodiphenyl sulfide and anhydrous potassium carbonate with a mass ratio of 1:3:0.2:3 are added into a reaction kettle and uniformly mixed, 3 times the mass of a mixed solvent of N,N-dimethylacetamide and toluene is added, nitrogen is introduced, the temperature is increased to 140 DEG C and refluxed for 4 hours, the temperature is increased to 160-170 DEG C and the reaction is continued for 8-10 hours, the temperature is cooled to room temperature, the reaction solution is poured into deionized water for precipitation, ethanol washing is performed for 3 times, vacuum drying is performed, vacuum annealing is performed at 180 DEG C for 4 hours, and a modified polyaryletherketone matrix is obtained, wherein the mass ratio of N,N-dimethylacetamide and toluene is 3:1;

[0011] 1,4-hydroquinone, 4,4'-dichlorodiphenyl sulfone, 4,4'-dimercaptodiphenyl sulfide and anhydrous potassium carbonate with a mass ratio of 1:3:0.2:3 are added into a reaction kettle and uniformly mixed, 3 times the mass of a mixed solvent of N,N-dimethylacetamide and toluene is added, nitrogen is introduced, the temperature is increased to 140 DEG C and refluxed for 4 hours, the temperature is increased to 160-170 DEG C and the reaction is continued for 8-10 hours, the temperature is cooled to room temperature, the reaction solution is poured into deionized water for precipitation, ethanol washing is performed for 3 times, vacuum drying is performed, vacuum annealing is performed at 180 DEG C for 4 hours, and a modified polyaryletherketone matrix is obtained, wherein the mass ratio of N,N-dimethylacetamide and toluene is 3:1;

[0012] 1,4-hydroquinone, 4,4'-dichlorodiphenyl sulfone, 4,4'-dimercaptodiphenyl sulfide and anhydrous potassium carbonate with a mass ratio of 1:3:0.2:3 are added into a reaction kettle and uniformly mixed, 3 times the mass of a mixed solvent of N,N-dimethylacetamide and toluene is added, nitrogen is introduced, the temperature is increased to 140 DEG C and refluxed for 4 hours, the temperature is increased to 160-170 DEG C and the reaction is continued for 8-10 hours, the temperature is cooled to room temperature, the reaction solution is poured into deionized water for precipitation, ethanol washing is performed for 3 times, vacuum drying is performed, vacuum annealing is performed at 180 DEG C for 4 hours, and a modified polyaryletherketone matrix is obtained, wherein the mass ratio of N,N-dimethylacetamide and toluene is 3:1;

[0013] 1,4-hydroquinone, 4,4'-dichlorodiphenyl sulfone, 4,4'-dimercaptodiphenyl sulfide and anhydrous potassium carbonate with a mass ratio of 1:3:0.2:3 are added into a reaction kettle and uniformly mixed, 3 times the mass of a mixed solvent of N,N-dimethylacetamide and toluene is added, nitrogen is introduced, the temperature is increased to 140 DEG C and refluxed for 4 hours, the temperature is increased to 160-170 DEG C and the reaction is continued for 8-10 hours, the temperature is cooled to room temperature, the reaction solution is poured into deionized water for precipitation, ethanol washing is performed for 3 times, vacuum drying is performed, vacuum annealing is performed at 180 DEG C for 4 hours, and a modified polyaryletherketone matrix is obtained, wherein the mass ratio of N,N-dimethylacetamide and toluene is 3:1;

[0014] The reaction among 1,4-hydroquinone, 4,4'-dichlorodiphenyl sulfone, 4,4'-dimercaptodiphenyl sulfide and anhydrous potassium carbonate can be divided into three stages:

[0015] The first stage is active site activation: the sulfonyl group (-SO2-) in the 4,4'-dichlorodiphenyl sulfone molecule is a strong electron-withdrawing group, which significantly reduces the electron cloud density on the adjacent aromatic ring through resonance effect and induction effect, making the carbon atoms adjacent to and opposite to the chlorine atom the active sites with the lowest electron cloud density, thus creating conditions for the attack of nucleophiles;

[0016] The second stage is nucleophilic attack and transition state formation: 1,4-hydroquinone and 4,4'-dimercaptodiphenyl sulfide react with potassium carbonate to form salts, and the oxygen anions have strong nucleophilicity and can attack the active sites of 4,4'-dichlorodiphenyl sulfone to form a negatively charged aromatic transition state, at which time the aromatic ring is transformed from sp 2 hybridization to sp 3 hybridization, forming an unstable five-membered ring transition structure;

[0017] The third stage is the departure of the leaving group and chain growth: the transition state rapidly rearranges, and the chlorine atom is removed from the aromatic ring as a leaving group, and the aromatic ring restores the stable sp 2 hybridization structure, and at the same time, an ether bond (-O-) is formed between the salt and 4,4'-dichlorodiphenyl sulfone. Since the 4,4'-dichlorodiphenyl sulfone molecule contains two chlorine atoms, and the salt molecule contains two oxygen anions, the above nucleophilic substitution reaction can be recycled, with each 4,4'-dichlorodiphenyl sulfone molecule being connected to two salt molecules, and each salt molecule being connected to two 4,4'-dichlorodiphenyl sulfone molecules. Finally, a long-chain polymer with -O-Ar1-O-Ar2-SO2- as the repeating unit is formed, and the degree of polymerization n is controlled within the range of 50-100;

[0018]

[0019] One of the advantages of the modified polyaryletherketone matrix core prepared by the above steps is that the mercapto group (-SH) is integrated. The mercapot group of 4,4'-dithiodimercaptobenzene reacts with anhydrous potassium carbonate to form a mercapto salt nucleophile, which cooperates with the phenoxide generated by the phenolic hydroxyl group to participate in the nucleophilic substitution reaction, so that the main chain is precisely introduced into the sulfide bond (-S-) in addition to the ether bond and the sulfone group. The sulfur atom in the sulfide bond derived from the mercapto group contains a lone pair of electrons, which can form "O-S cooperative coordination" with the oxygen atom of the ether bond, greatly increasing the lithium ion coordination site, significantly improving the lithium salt dissociation efficiency and building a more dense ion transmission channel; At the same time, the rigid aromatic structure of the sulfide bond is combined with the conjugated system of the main chain, further enhancing the high temperature anti-creep performance of the matrix, and the chemical stability of sulfur also gives the matrix better oxidation resistance and electrolyte corrosion resistance, which meets the long-term cycle demand of high-voltage cathode; In addition, the matrix still retains the inherent high heat resistance and mechanical strength of polyaryletherketone. The molecular chain regularity optimized by annealing superimposes the polarity regulation of the sulfide bond, which also enhances the interfacial compatibility with the modified boron-nitrogen-doped graphene and nitrogen-containing heterocyclic toughening agent. It effectively solves the core defects of the traditional matrix, such as the sudden drop of ion conductivity at high temperature, the attenuation of mechanical strength, and the insufficient anti-deterioration performance. The sulfide bond derived from the mercapto group is the key to the synergistic improvement of ion conduction and structural stability, which lays the foundation for the wide temperature range and high performance of the composite material;

[0020] S102: Citric acid, boric acid and urea with a mass ratio of 5:1:2 were dissolved in deionized water and ultrasonically treated for 30 min, then transferred to a high-pressure reaction kettle with a polytetrafluoroethylene liner and reacted at 180℃ for 12 h. After cooling to room temperature, it was dialyzed for 5 times and vacuum dried at 60℃. Then it was immersed in a 3-aminopropyltriethoxysilane reagent hydrolysate for 1 h, washed with ethanol for 3 times and vacuum dried to obtain modified boron-nitrogen-doped graphene nanoparticles;

[0021] Lemon acid (carbon source), boric acid (boron source) and urea (nitrogen source and structure directing agent) were mixed in an aqueous solution, and ultrasonic treatment was used to ensure uniform molecular dispersion. Under the high-pressure hydrothermal environment at 180℃, a series of complex dehydration, condensation and aromatization reactions occurred. The citric acid molecules were dehydrated to form C-C covalent bonds, gradually building a graphite-like six-membered ring carbon skeleton. The urea thermal decomposition produced active nitrogen-containing species such as ammonia (NH3) and isocyanic acid (HCNO), which not only doped into the carbon skeleton as a nitrogen source, but also promoted the graphitization of citric acid molecules in the alkaline reducing atmosphere, and regulated the size and surface state of the nanoparticles.

[0022] C6H8O7 (citric acid) → C (graphene skeleton) + H2O↑ + CO↑;

[0023] CO(NH2)2→NH3↑+HNCO;

[0024] HNCO+H2O→NH3↑+CO2↑;

[0025] Boric acid is decomposed into boron oxide (B2O3), and the boron atoms in the boron oxide partially replace the carbon atoms in the lattice under high-temperature hydrothermal conditions, forming B-C bonds and achieving boron doping. The high-pressure environment can inhibit the escape of volatile substances and promote the penetration of boron and nitrogen atoms into the carbon skeleton, improving the uniformity of doping. The 12-hour long reaction time ensures complete carbonization and forms a nanoparticle structure with moderate crystallinity.

[0026] C (graphene skeleton) + B2O3→ B-C (doping);

[0027] C (graphene skeleton) + NH3→ N-C (doping);

[0028] After cooling, dialysis 5 times (using a dialysis bag with a molecular weight cutoff of 1000-3000 Da) can remove small molecular impurities that do not participate in the reaction, such as uncarbonized citric acid, excess boric acid, and urea decomposition residues, to avoid the influence of impurities on the subsequent modification effect. Vacuum drying at 60°C can not only remove the water adsorbed on the surface of the particles, but also prevent oxidation of the particles caused by high temperature, obtaining dry boron-nitrogen-doped graphene nanoparticle crude product.

[0029] Ammonia propyl triethoxysilane is a silane coupling agent that undergoes hydrolysis in water: its ethoxy group (-OC2H5) is converted to a hydroxyl group (-OH), generating an active intermediate containing silicon hydroxyl groups. Subsequently, the silicon hydroxyl groups undergo condensation reactions with the hydroxyl groups (oxygen-containing groups remaining from the carbonization process) on the surface of the boron-nitrogen-doped graphene nanoparticles, grafting organic segments containing amino groups (-NH2) onto the particle surface. This modification introduces hydrophilic and reactive amino groups, enhancing the interfacial bonding between the particles and the modified polyaryletherketone matrix (amino groups can form hydrogen bonds with the ether bonds and sulfonyl groups in the matrix). Ethanol washing 3 times is used to remove unreacted silane reagent monomers, and vacuum drying finally obtains surface amino-functionalized modified boron-nitrogen-doped graphene nanoparticles.

[0030]

[0031] The addition of modified boron-nitrogen doped graphene nanoparticles can serve as a rigid reinforcing framework for the composite material on the basis of its two-dimensional sheet structure and high mechanical strength, and can improve the tensile properties and structural stability of the material at high temperatures in cooperation with the nitrogen-containing heterocyclic rigid toughener to inhibit high-temperature creep. On the other hand, the polar sites formed by boron-nitrogen co-doping can coordinate with lithium ions to construct a continuous ion transport channel, reduce the lithium ion migration energy barrier, and significantly improve the wide-temperature-range ionic conductivity of the composite material. Meanwhile, the amino groups introduced on the surface of the nanoparticles by silane modification can form hydrogen bonds with the ether bonds and sulfone groups of the modified polyaryletherketone matrix, effectively improving the dispersion uniformity of the nanoparticles in the matrix, avoiding the blockage of ion transport channels caused by agglomeration, and further improving the high-temperature resistance limit and oxidation decomposition voltage of the composite material due to the excellent thermal stability and electrochemical inertness brought by boron-nitrogen doping, ensuring the compatibility with high-voltage positive electrode materials, and finally realizing the synergistic optimization of ion conduction, mechanical strength, high-temperature stability and component compatibility of the composite material.

[0032] S2: Preparation of the precursor solution:

[0033] The modified polyaryletherketone matrix was weighed according to the proportion, added into N-methylpyrrolidone solvent, and stirred at 85°C for 6-8h to form a transparent viscous solution with a solid content of 10wt%. The polybenzimidazole powder was added in proportion, and the stirring was continued at 80°C for 4h. The lithium salt solution was slowly added, and the stirring was continued at 70°C for 2h to obtain the precursor solution.

[0034] First, the modified polyaryletherketone matrix was weighed according to the proportion and added into N-methylpyrrolidone (NMP) solvent, and stirred at 85°C for 6-8h to form a transparent viscous solution with a solid content of 10wt%. NMP, as a strong polar aprotic solvent, can form hydrogen bonds with the ether bonds (-O-), sulfone groups (-SO2-) and sulfide bonds (-S-) of the modified polyaryletherketone matrix through intermolecular forces, destroy the van der Waals forces between the polyaryletherketone molecules and their hydrogen bonds, and make the polymer chain segments fully stretch and dissolve. The temperature setting of 85°C not only improves the solvent molecular motion rate and accelerates the dissolution process, but also avoids the degradation of the polyaryletherketone matrix caused by high temperature. The solid content of 10wt% takes into account the solution flowability and thickness uniformity of the subsequent film formation, avoiding the problems of too thin film layer caused by too low solid content or uneven dispersion caused by too high solid content.

[0035] Subsequently, polybenzimidazole (PBI) powder was added in proportion, and stirring was continued at 80°C for 4h. As a nitrogen-containing heterocyclic polymer, PBI has strong polarity between the nitrogen atom (-N=) on the imidazole ring and the amino group (-N-H), and can form hydrogen bonds with the solvent to achieve dissolution. At the same time, the N atom and N-H bond of the PBI imidazole ring can form multiple hydrogen bonds with the ether oxygen, sulfonyl oxygen and sulfide sulfur of the modified polyaryletherketone backbone. The stirring temperature of 80°C maintains the solubility of the system and avoids the dissociation of hydrogen bonds caused by excessive temperature. Through 4h of sufficient stirring, PBI is uniformly dispersed in the polyaryletherketone matrix solution, and the rigid heterocyclic structure can also be preliminarily anchored in the matrix segment through intermolecular forces, laying the foundation for subsequent improvement of the mechanical strength of the composite material;

[0036] Finally, the lithium salt solution was slowly added, and stirring was continued at 70°C for 2h to obtain the precursor solution. Lithium ions (Li + ) in the lithium salt solution have empty orbitals and can act as electron acceptors to coordinate with the electron-rich sites in the system: Specifically, Li + forms a multi-ligand coordination complex with the ether oxygen (-O-), sulfide sulfur (-S-), sulfonyl oxygen (-SO2-) of the modified polyaryletherketone, and the nitrogen atom (-N=) of the PBI imidazole ring. Slow addition is to avoid local lithium salt concentration too high leading to Li + agglomeration, and the temperature setting of 70°C can balance the molecular motion rate and coordination stability, which can promote Li + to fully coordinate with each polar site, and prevent the dissociation of coordination bonds caused by high temperature. 2h of continuous stirring ensures uniform dispersion and complete dissociation of lithium salt, avoiding the influence of undissociated lithium salt particles on subsequent ion transport efficiency;

[0037] S3: Dispersion and compounding of fillers:

[0038] The modified boron-nitrogen doped graphene nanoparticles were added to the precursor solution, ultrasonic treatment was performed for 30min, and then the solution was transferred into a 70°C oil bath and stirred for 3h to obtain an electrolyte casting solution.

[0039] After adding the modified particles to the precursor, 30min of ultrasonic treatment was performed, which took cavitation effect as the core. Bubbles in the solution were rapidly generated and broken, producing impact force and shear force, which broke the agglomerates of the particles formed by van der Waals force and hydrogen bonds, and dispersed them into low-aggregated state. At the same time, ultrasonic treatment promoted the contact between the solution and the particle surface, exposed the amino groups and boron-nitrogen doped sites introduced by the silane reagent modification, and created conditions for subsequent interfacial action;

[0040] Subsequently, 70°C oil bath stirring for 3h, 70°C to enhance the rate of molecular thermal motion, help particles uniform diffusion, but also to avoid the precursor has been formed in the coordination bond, hydrogen bond dissociation; continuous stirring can effectively inhibit the secondary agglomeration of particles, more importantly, the formation of multiple interface stabilization at this stage: modified boron and nitrogen-doped graphene surface amino (-NH2) can form hydrogen bonds with poly (aryl ether ketone) ether oxygen (-O-), sulfonyl oxygen (-SO2-) and PBI imidazole ring N-H bond, the surface of the particle boron atom (containing lone pair of electrons), nitrogen atom can form weak coordination with lithium ions (Li + ) in the precursor, at the same time, the two-dimensional sheet structure of the particles through the van der Waals force and polymer chain segment adsorption, these interactions will be firmly anchored in the polymer matrix nanoparticles, both to avoid the agglomeration of particles caused by ion transport channel blockage, and through the interface interaction to build the lithium ion transport "interface channel", ultimately form a uniform dispersion, good stability of the electrolyte casting solution;

[0041] S4: casting and heat treatment:

[0042] The electrolyte casting solution is poured on a flat polytetrafluoroethylene or glass substrate, and an automatic film scraper is used to control the wet film thickness of 300-500μm, and gradient heat treatment is carried out in vacuum;

[0043] The casting solution is poured on a polytetrafluoroethylene or glass substrate, and the surface of the two is smooth and chemically inert, which can avoid the adhesion of the casting solution or the occurrence of side reactions, and at the same time ensure the smooth peeling of the subsequent film layer; an automatic film scraper is used to control the wet film thickness of 300-500μm, which not only ensures the uniformity of the final dry film thickness through precise thickness control, but also avoids the local unevenness caused by manual film scraping, laying a foundation for the uniformity of the film performance;

[0044] Gradient heat treatment in vacuum is the key: vacuum conditions can isolate oxygen to prevent film layer oxidation at high temperature, and accelerate solvent evaporation to avoid the influence of residual solvent on film structure stability; gradient heating realizes function optimization in stages: slow removal of most solvents at 80°C low temperature stage to prevent solvent from escaping to form holes, cracks and other defects; 120°C medium temperature stage promotes polymer chain segment movement, promotes modified boron and nitrogen-doped graphene and substrate interface further fusion, reduces the gap between components; 150°C high temperature stage realizes the final curing of the film structure, locks the molecular arrangement and component distribution, and eliminates the residual stress in the film, improves the thermal dimensional stability and mechanical integrity of the film. The whole process realizes the progress of "forming-densification-stability" of the film layer through physical means, and finally obtains a uniform and dense composite electrolyte membrane with stable structure;

[0045] S5: post-processing:

[0046] After heat treatment, natural cooling to room temperature, the self-supporting composite material is peeled off from the substrate, punched into the required shape as needed, placed in a glove box filled with argon for use;

[0047] After heat treatment, natural cooling to room temperature, the self-supporting composite material is peeled off from the substrate, punched into the required shape as needed, placed in a glove box filled with argon for use;

[0048] Punching into shape is to adapt to the electrode size of different specifications of solid-state battery, improve the practicality of adaptability; argon is an inert gas, the argon atmosphere in the glove box can isolate air and moisture, avoid the moisture absorption and oxidation of lithium salt in the film, prevent the reaction of film components and oxygen, maintain its electrochemical activity, and ensure the performance stability during subsequent battery assembly.

[0049] Preferably, the lithium salt is one or more of lithium bistrifluoromethanesulfonimide, lithium bisfluorosulfonimide, lithium hexafluorophosphate, all with a purity of ≥99.9%, and the preparation method of the lithium salt solution is: adding lithium salt into N-methyl pyrrolidone solvent in proportion, stirring and dissolving at room temperature, to obtain a lithium salt solution.

[0050] Preferably, the specific parameters of ultrasonic treatment are: power 500W, working 2s, stopping 2s, total time 30min.

[0051] Preferably, the specific parameters of gradient heat treatment are: vacuum drying at 80℃ for 12h, vacuum drying at 120℃ for 6h, and finally vacuum drying at 150℃ for 2h.

[0052] Compared with the prior art, the beneficial effects of the present application are:

[0053] 1、The present application adopts 4,4'-dimercaptodiphenyl sulfide to participate in nucleophilic substitution polymerization, precisely introduces sulfide bond in polyaryletherketone main chain, constructs "O-S synergistic coordination" system with ether bond and sulfone group, cooperates with the double regulation mechanism of mercapto derivative sulfide bond, solves the core problem of mutual exclusion of ion conductivity and mechanical strength at high temperature of traditional matrix. Mercapto salt and phenolate salt synergistically polymerize to form stable alternating main chain, the lone pair electrons of sulfur atom and ether oxygen synergistically increase the coordination site of lithium ion, the rigid structure of sulfide bond strengthens the high temperature creep resistance, so that the material still maintains ≥8MPa tensile strength and 10 -3 S / cm level of ion conductivity at 150℃.

[0054] 2, The application adopts the means of boric acid-urea synergistic doping and silane modification to prepare surface amino functionalized boron-nitrogen doped graphene, and solves the problems of inorganic filler agglomeration and poor interface compatibility by cooperating with the interface multiple non-covalent interaction mechanism. The boron-nitrogen uniform doping constructs a polar site and a two-dimensional reinforcing skeleton, the amino forms a hydrogen bond with the matrix and PBI, and the boron-nitrogen site weakly coordinates with lithium ions, so that the filler agglomeration is avoided, a continuous ion transmission channel is constructed, and the high-temperature mechanical strength and the electrochemical window are simultaneously improved to ≥5.0 V.

[0055] 3, The application adopts the means of modified polyaryletherketone-polybenzimidazole-lithium salt-boron-nitrogen graphene step-by-step composite system, cooperates with the multi-component synergistic mechanism, and realizes the balanced improvement of comprehensive performance in a wide temperature range. The modified polyaryletherketone provides heat resistance and conduction basis, the polybenzimidazole enhances the mechanical strength and interface compatibility, the modified boron-nitrogen graphene cooperatively optimizes the performance, and the lithium salt is efficiently dissociated through multi-site coordination; the components form a stable system through non-covalent interaction, so that the material maintains a high ionic conductivity of 10 -4 -10 -3 S / cm in a wide temperature range of 25-150 DEG C, and breaks the limitation of single performance improvement at the expense of other performances. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 A process flow chart for preparing a high polymer electrolyte composite material. DETAILED DESCRIPTION

[0057] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application.

[0058] Embodiment 1: a preparation method of a high polymer electrolyte composite material for a high-temperature-resistant solid-state battery:

[0059] S1: preparation of key functional components:

[0060] S101: 1,4-hydroquinone, 4,4'-dichlorodiphenyl sulfone, 4,4'-dimercaptodiphenyl sulfide and anhydrous potassium carbonate with a mass ratio of 1:3:0.2:3 are added into a reaction kettle and uniformly mixed, 3 times the mass of a mixed solvent of N,N-dimethylacetamide and toluene is added, nitrogen is introduced, the temperature is increased to 140 DEG C and refluxed for 4 h, the temperature is increased to 165 DEG C and the reaction is continued for 8-10 h, the temperature is cooled to room temperature, precipitated in deionized water, washed with ethanol for 3 times, vacuum dried, and then vacuum annealed at 180 DEG C for 4 h to obtain a modified polyaryletherketone matrix, wherein the mass ratio of N,N-dimethylacetamide and toluene is 3:1;

[0061] S102: Citric acid, boric acid and urea with a mass ratio of 5:1:2 were dissolved in deionized water together, ultrasonic treatment for 30 min, transferred to a high-pressure reaction kettle with a polytetrafluoroethylene liner, reacted at 180°C for 12 h, cooled to room temperature, dialyzed for 5 times, vacuum dried at 60°C, immersed in 3-aminopropyl triethoxysilane reagent hydrolyzate for 1 h, washed with ethanol for 3 times, vacuum dried, and modified boron-nitrogen doped graphene nanoparticles were obtained;

[0062] S2: Preparation of precursor solution:

[0063] 40 parts of modified polyaryletherketone matrix were weighed, N-methylpyrrolidone solvent was added, stirred at 85°C for 7 h to form a transparent viscous solution with a solid content of 10wt%, 15 parts of polybenzimidazole powder were added, and stirring was continued at 80°C for 4 h, 20 parts of lithium salt solution were slowly added, and stirring was continued at 70°C for 2 h to obtain a precursor solution;

[0064] S3: Dispersion and compounding of fillers:

[0065] 10 parts of modified boron-nitrogen doped graphene nanoparticles were added to the precursor solution, ultrasonic treatment for 30 min, then transferred into a 70°C oil bath, and stirred for 3 h to obtain an electrolyte casting solution;

[0066] S4: Casting and heat treatment:

[0067] The electrolyte casting solution was poured onto a flat polytetrafluoroethylene or glass substrate, and an automatic film scraper was used to control the wet film thickness to be 300-500μm, and gradient heat treatment was carried out in vacuum;

[0068] S5: Post-processing:

[0069] After heat treatment, the self-supporting composite material was peeled off from the substrate, cut into the required shape as needed, and placed in an argon-filled glove box for use.

[0070] Example 2: Preparation method of high-temperature-resistant solid-state battery polymer electrolyte composite material:

[0071] S1: Preparation of key functional components:

[0072] S101: 1,4-hydroquinone, 4,4'-dichlorodiphenyl sulfone, 4,4'-dimercaptodiphenyl sulfide and anhydrous potassium carbonate with a mass ratio of 1:3:0.2:3 were added into a reaction kettle and uniformly mixed, then 3 times the mass of N,N-dimethylacetamide and toluene mixed solvent was added, nitrogen was introduced, the temperature was increased to 140 DEG C and refluxed for 4h, the temperature was increased to 165 DEG C and the reaction was continued for 8-10h, and then the temperature was cooled to room temperature, poured into deionized water for precipitation, washed with ethanol for 3 times, vacuum dried, then vacuum annealed at 180 DEG C for 4h, and the modified polyaryletherketone matrix was obtained, wherein the mass ratio of N,N-dimethylacetamide and toluene is 3:1;

[0073] S102: citric acid, boric acid and urea with a mass ratio of 5:1:2 were dissolved in deionized water, ultrasonic treatment was performed for 30 min, and then transferred to a high-pressure reaction kettle with a polytetrafluoroethylene liner, reacted at 180 DEG C for 12h, cooled to room temperature, dialyzed for 5 times, vacuum dried at 60 DEG C, immersed in 3-aminopropyl triethoxysilane reagent hydrolysate for 1h, washed with ethanol for 3 times, and vacuum dried to obtain modified boron-nitrogen doped graphene nanoparticles;

[0074] S2: Preparation of precursor solution:

[0075] 60 parts of modified polyaryletherketone matrix were weighed, N-methyl pyrrolidone solvent was added, stirred at 85 DEG C for 7h to form a transparent viscous solution with a solid content of 10wt%, 15 parts of polybenzimidazole powder was added, and the stirring was continued at 80 DEG C for 4h, 20 parts of lithium salt solution was slowly added, and the stirring was continued at 70 DEG C for 2h to obtain the precursor solution;

[0076] S3: Dispersion and compounding of fillers:

[0077] 10 parts of modified boron-nitrogen doped graphene nanoparticles were added into the precursor solution, ultrasonic treatment was performed for 30 min, and then transferred into a 70 DEG C oil bath, and stirred for 3h to obtain an electrolyte casting solution;

[0078] S4: Casting and heat treatment:

[0079] The electrolyte casting solution was poured onto a flat polytetrafluoroethylene or glass substrate, an automatic film scraper was used to control the wet film thickness to be 300-500μm, and gradient heat treatment was performed in a vacuum;

[0080] S5: Post-processing:

[0081] After heat treatment, the self-supporting composite material was peeled off from the substrate, cut into the required shape as needed, and placed in an argon-filled glove box for use.

[0082] Example 3: Preparation method of high molecular electrolyte composite material for high-temperature resistant solid-state battery:

[0083] S1: Preparation of key functional components:

[0084] S101: 1,4-hydroquinone, 4,4'-dichlorodiphenyl sulfone, 4,4'-dimercaptodiphenyl sulfide and anhydrous potassium carbonate with a mass ratio of 1:3:0.2:3 were added into a reaction kettle and mixed uniformly, then 3 times the mass of N,N-dimethylacetamide and toluene mixed solvent was added, nitrogen was introduced, the temperature was raised to 140°C and refluxed for 4h, then the temperature was raised to 165°C and the reaction was continued for 8-10h, then the temperature was cooled to room temperature, poured into deionized water for precipitation, washed with ethanol for 3 times, vacuum dried, then vacuum annealed at 180°C for 4h, to obtain a modified polyaryletherketone matrix, wherein the mass ratio of N,N-dimethylacetamide and toluene is 3:1;

[0085] S102: Citric acid, boric acid and urea with a mass ratio of 5:1:2 were dissolved in deionized water together, ultrasonic treatment for 30min, transferred to a high-pressure reaction kettle with a polytetrafluoroethylene liner, reacted at 180°C for 12h, cooled to room temperature, dialyzed for 5 times, vacuum dried at 60°C, immersed in 3-aminopropyl triethoxysilane reagent hydrolysate for 1h, washed with ethanol for 3 times, vacuum dried, to obtain modified boron-nitrogen doped graphene nanoparticles;

[0086] S2: Preparation of precursor solution:

[0087] 50 parts of modified polyaryletherketone matrix was weighed, N-methyl pyrrolidone solvent was added, stirred at 85°C for 7h to form a transparent viscous solution with a solid content of 10wt%, 15 parts of polybenzimidazole powder was added, continued to stir at 80°C for 4h, 20 parts of lithium salt solution was slowly added, continued to stir at 70°C for 2h, to obtain a precursor solution;

[0088] S3: Dispersion and compounding of fillers:

[0089] 10 parts of modified boron-nitrogen doped graphene nanoparticles was added into the precursor solution, ultrasonic treatment for 30min, then transferred into a 70°C oil bath, stirred for 3h, to obtain an electrolyte casting solution;

[0090] S4: Casting and heat treatment:

[0091] The electrolyte casting solution was poured onto a flat polytetrafluoroethylene or glass substrate, the wet film thickness was controlled to be 300-500μm using an automatic film scraper, and gradient heat treatment was carried out in vacuum;

[0092] S5: Post-processing:

[0093] After heat treatment, the self-supporting composite material was naturally cooled to room temperature, peeled off from the substrate, cut into the required shape as needed, and placed in an argon-filled glove box for use.

[0094] Embodiment 4: Preparation method of high-temperature-resistant solid-state battery polymer electrolyte composite

[0095] S1: Preparation of key functional components

[0096] S101: 1,4-hydroquinone, 4,4'-dichlorodiphenyl sulfone, 4,4'-dimercaptodiphenyl sulfide, and anhydrous potassium carbonate with a mass ratio of 1:3:0.1:3 were added into a reaction kettle and uniformly mixed, 3 times the mass of N,N-dimethylacetamide and toluene mixed solvent was added, nitrogen was introduced, the temperature was raised to 140°C and refluxed for 4h, the temperature was raised to 165°C and the reaction was continued for 8-10h, cooled to room temperature, poured into deionized water for precipitation, washed with ethanol for 3 times, vacuum dried, then vacuum annealed at 180°C for 4h, to obtain a modified polyaryletherketone matrix, wherein the mass ratio of N,N-dimethylacetamide and toluene is 3:1;

[0097] S102: Citric acid, boric acid, and urea with a mass ratio of 5:1:2 were dissolved in deionized water and ultrasonically treated for 30min, then transferred to a high-pressure reaction kettle with a polytetrafluoroethylene liner and reacted at 180°C for 12h, cooled to room temperature, dialyzed for 5 times, vacuum dried at 60°C, immersed in a 3-aminopropyltriethoxysilane reagent hydrolysate for 1h, washed with ethanol for 3 times, and vacuum dried to obtain modified boron-nitrogen-doped graphene nanoparticles;

[0098] S2: Preparation of precursor solution

[0099] 50 parts of the modified polyaryletherketone matrix was weighed, N-methylpyrrolidone solvent was added, stirred at 85°C for 7h to form a transparent viscous solution with a solid content of 10wt%, 15 parts of polybenzimidazole powder was added, and the stirring was continued at 80°C for 4h, 20 parts of lithium salt solution was slowly added, and the stirring was continued at 70°C for 2h to obtain the precursor solution;

[0100] S3: Dispersion and compounding of fillers

[0101] 10 parts of the modified boron-nitrogen-doped graphene nanoparticles was added into the precursor solution, ultrasonically treated for 30min, then transferred into a 70°C oil bath and stirred for 3h to obtain an electrolyte casting solution;

[0102] S4: Casting and heat treatment

[0103] The electrolyte casting solution was poured onto a flat polytetrafluoroethylene or glass substrate, an automatic film coater was used to control the wet film thickness to be 300-500μm, and gradient heat treatment was performed in a vacuum;

[0104] S5: Post-treatment

[0105] After heat treatment, natural cooling to room temperature, the self-supporting composite material is peeled off from the substrate, punched into the required shape as needed, placed in a glove box filled with argon for use.

[0106] Example 5: Preparation method of high-temperature-resistant solid-state battery polymer electrolyte composite material:

[0107] S1: Preparation of key functional components:

[0108] S101: 1,4-hydroquinone, 4,4'-dichlorodiphenyl sulfone, 4,4'-dimercaptodiphenyl sulfide and anhydrous potassium carbonate with a mass ratio of 1:3:0.2:3 are added into a reaction kettle and uniformly mixed, then 3 times the mass of N,N-dimethylacetamide and toluene mixed solvent is added, nitrogen is introduced, the temperature is raised to 140°C and refluxed for 4h, the temperature is raised to 165°C and the reaction is continued for 8-10h, the temperature is cooled to room temperature, poured into deionized water for precipitation, washed with ethanol for 3 times, vacuum dried, then vacuum annealed at 180°C for 4h to obtain a modified polyaryletherketone matrix, wherein the mass ratio of N,N-dimethylacetamide and toluene is 3:1;

[0109] S102: Citric acid, boric acid and urea with a mass ratio of 5:1:2 are dissolved in deionized water, ultrasonic treated for 30min, transferred to a polytetrafluoroethylene lined high-pressure reaction kettle, reacted at 180°C for 12h, cooled to room temperature, dialyzed for 5 times, vacuum dried at 60°C, immersed in 3-aminopropyltriethoxysilane reagent hydrolysate for 1h, washed with ethanol for 3 times, vacuum dried to obtain modified boron-nitrogen doped graphene nanoparticles;

[0110] S2: Preparation of precursor solution:

[0111] 50 parts of modified polyaryletherketone matrix is weighed, N-methylpyrrolidone solvent is added, stirred at 85°C for 7h to form a transparent viscous solution with a solid content of 10wt%, 15 parts of polybenzimidazole powder is added, continue to stir at 80°C for 4h, slowly add 20 parts of lithium salt solution, continue to stir at 70°C for 2h to obtain the precursor solution;

[0112] S3: Dispersion and compounding of fillers:

[0113] 5 parts of modified boron-nitrogen doped graphene nanoparticles is added into the precursor solution, ultrasonic treated for 30min, then transferred into a 70°C oil bath, stirred for 3h to obtain an electrolyte casting solution;

[0114] S4: Casting film and heat treatment:

[0115] The electrolyte casting solution is poured onto a flat polytetrafluoroethylene or glass substrate, the wet film thickness is controlled to be 300-500μm using an automatic film scraper, and gradient heat treatment is carried out in vacuum;

[0116] S5: Post-processing:

[0117] After heat treatment, naturally cool to room temperature, peel off the self-supporting composite material from the substrate, punch into the required shape as needed, and place in an argon-filled glove box for use.

[0118] Comparative Example 1:

[0119] Compared with Example 3, the modified polyaryletherketone matrix in Comparative Example 1 weighs 70 parts dissolved in the solvent.

[0120] Comparative Example 2:

[0121] Compared with Example 3, no 4,4'-dimercaptodiphenyl sulfide was added during the preparation of the modified polyaryletherketone matrix in Comparative Example 2.

[0122] Comparative Example 3:

[0123] Compared with Example 3, the boron-nitrogen-doped graphene nanoparticles in Comparative Example 3 were not modified with a silane reagent.

[0124] Comparative Example 4:

[0125] Compared with Example 3, no polybenzimidazole was added in Step S2 of Comparative Example 4.

[0126] Comparative Example 5:

[0127] Compared with Example 3, no gradient heat treatment was performed in S4 of Comparative Example 5, but instead vacuum drying was directly performed at 120°C for 20h.

[0128] Comparative Example 6:

[0129] Compared with Example 3, polyethylene oxide was used instead of the modified polyaryletherketone matrix in Comparative Example 6.

[0130] Performance Test:

[0131] According to the tests in GB / T 1040.4-2006 "Determination of tensile properties of plastics - Part 4: test conditions for films and sheets", GB / T 27761-2011 "Thermogravimetric analysis for determination of thermal stability of solid materials", GB / T 19466.2-2004 "Differential scanning calorimetry (DSC) for plastics - Part 2: determination of glass transition temperature", and GB / T 6283-2008 "Determination of moisture content in chemical products - Karl Fischer method", the tensile strength, elongation at break, thermal decomposition temperature, residual mass, glass transition temperature, and trace moisture content of the present application were determined.

[0132] Ion Conductivity Test:

[0133] Test steps: 1. The electrolyte membrane was punched into a 12mm diameter disc and placed in an argon glove box to assemble a stainless steel (SS) / electrolyte membrane / stainless steel (SS) symmetrical battery;

[0134] 2. The electrochemical workstation was used to test at 25℃ and 150℃ constant temperature environment respectively, with a frequency range of 1Hz-1MHz and an alternating current amplitude of 10mV;

[0135] 3. The resistance value at the intersection of the high-frequency area semicircle and the real axis in the Nyquist plot was read, which was the bulk resistance (Rb, unit: Ω);

[0136] 4. The thickness (L, unit: cm) of the membrane at three different positions was measured by a screw micrometer, and the average value was taken; the effective contact area of the electrode (A, unit: cm 2 , A=πd 2 / 4, d is the electrode diameter, unit: cm).

[0137] The calculation formula is: σ=L / (R b ×A), where σ is the ionic conductivity (unit: S / cm), L is the membrane thickness, R b is the bulk resistance, and A is the electrode area.

[0138] Table 1 below shows the tensile strength, elongation at break, and trace moisture content test data of the electrolyte composite materials prepared in each example and comparative example at room temperature and 150℃ environment.

[0139]

[0140] Table 2 below shows the thermal decomposition temperature (T5%), residual mass at 600℃, glass transition temperature (Tg), and ionic conductivity test data of the electrolyte composite materials prepared in each example and comparative example at 25℃ and 150℃ environment.

[0141]

[0142] Data analysis:

[0143] Figure 1 The process flow chart for preparing the polymer electrolyte composite material is shown in the figure. First, the modified polyarylether sulfone ketone matrix and modified boron-nitrogen doped graphene nanoparticles and other key components are prepared; then the matrix is mixed with lithium salt and polybenzimidazole to prepare a precursor solution; the modified boron-nitrogen doped graphene nanoparticles are added to complete the filler dispersion and compounding; then the film is formed by casting and heat treated; finally, the target composite material is obtained through post-processing.

[0144] According to the performance test data shown in Table 1 and Table 2, the performance of each item of Example 3 presents the most optimal balance, and the mechanical strength, ionic conductivity and thermal stability are all at the ideal level. From the mechanism, the amount of the modified polyaryletherketone matrix, the content of the sulfide bond, the polybenzimidazole toughening agent and the modified boron-nitrogen-doped graphene filler form the optimal ratio in this example: the ether bond, the sulfone group and the sulfide bond of the matrix backbone construct a high-efficiency "O-S synergistic coordination" system, which fully improves the lithium salt dissociation efficiency; the filler is modified by silane and forms a stable interfacial interaction with the matrix, is uniformly dispersed and constructs a continuous ion transmission channel; the toughening agent enhances the interfacial compatibility and mechanical toughness through hydrogen bonding, and under the synergistic action of each component, not only the structural stability at high temperature is ensured, but also the efficient transmission of lithium ions is realized, and finally the comprehensive performance balance is achieved.

[0145] Compared with Example 3, the mechanical strength of Example 1 decreases slightly, and the ionic conductivity presents a small increase. Mechanically, the amount of the modified polyaryletherketone matrix in Example 1 is reduced, which leads to insufficient skeleton density of the support material structure and reduced molecular chain entanglement degree, and the mechanical strength, especially the anti-creep performance at high temperature, is affected; but the reduction of the matrix proportion increases the relative concentration of lithium salt and modified boron-nitrogen-doped graphene, and the ion coordination sites are more dense, and the matrix chain segment is more stretched, so the space resistance to lithium ion migration is reduced, and the ion transmission channel is more unobstructed, so the conductivity presents a small reverse increase.

[0146] Compared with Example 3, the mechanical strength of Example 2 is significantly improved, and the ionic conductivity decreases. Mechanically, the amount of the modified polyaryletherketone matrix in Example 2 is increased, which forms a more dense molecular chain network structure and improves the molecular chain entanglement degree, providing a more stable support skeleton for the material, so the mechanical strength, especially the structural stability at high temperature, is significantly enhanced; but the excess matrix leads to the dilution of the relative concentration of lithium salt in the system, the density of lithium ion coordination sites is reduced, and the dense molecular chain restricts the chain segment movement, hinders the migration of lithium ions, and the excess matrix blocks the ion transmission channel to some extent, finally leading to a significant decrease in the conductivity.

[0147] The mechanical strength of Comparative Example 1 is further improved compared to Example 3, but the elongation at break is significantly reduced, and the ionic conductivity is greatly reduced. Mechanistically, the amount of modified polyaryletherketone matrix in Comparative Example 1 is much higher than the standard example, forming a highly dense polymer network, and the degree of molecular chain entanglement reaches a peak, so the mechanical strength reaches the highest; but the excessive dense molecular chain seriously limits the flexible movement of the chain segment, resulting in poor material toughness and a sharp drop in elongation at break; at the same time, the excessive matrix greatly dilutes the effective concentration of lithium salt and filler, the ionic site density of the "O-S synergistic coordination" system is insufficient, and the dense matrix network blocks the lithium ion transmission channel, making the lithium ion migration energy barrier greatly increased, resulting in a sharp drop in conductivity, highlighting the negative inhibition of matrix dosage oversaturation on ion transport performance.

[0148] Compared with Example 3, the ionic conductivity of Example 4 decreases significantly, and the mechanical strength decreases slightly. Mechanistically, the amount of 4,4'-dimercaptodiphenyl sulfide in this example is reduced, resulting in a decrease in the amount of sulfide bond introduced into the modified polyaryletherketone backbone, and the "O-S synergistic coordination" system is not fully constructed, the lithium salt dissociation efficiency is reduced and the density of the ion transport channel is insufficient, which directly leads to a sharp drop in conductivity; at the same time, the rigid aromatic structure of the sulfide bond weakens the enhancement of the conjugated system of the main chain, resulting in a slight decrease in the mechanical support capacity of the material, ultimately showing the performance characteristics of a dominant decrease in conductivity.

[0149] Compared with Example 3, the mechanical strength and ionic conductivity of Example 5 both decrease significantly. Mechanistically, the amount of modified boron-nitrogen-doped graphene filler in this example is halved, the number of two-dimensional sheet structures as "rigid reinforcing framework" is insufficient, and the support network density formed with the polymer matrix is reduced, resulting in a decrease in mechanical strength, especially high-temperature creep resistance; at the same time, the reduction in the amount of filler greatly reduces the number of ion transport interface channels constructed on its surface, and the synergistic coordination of boron-nitrogen doping sites and lithium ions is weakened, the lithium ion migration path is discontinuous, ultimately leading to a synchronous decrease in mechanical strength and conductivity.

[0150] Compared with Example 3, the ionic conductivity of Comparative Example 2 decreases significantly, and the high-temperature mechanical strength also decreases significantly. The core reason is that Comparative Example 2 does not add 4,4'-dimercaptodiphenyl sulfide, and the sulfide bond is completely missing in the modified polyaryletherketone backbone, the "O-S synergistic coordination" system cannot be formed, the lithium salt dissociation lacks the synergistic effect of sulfur atom lone pair electrons, the ionic coordination site is greatly reduced and the transmission channel is sparse, resulting in a sharp drop in conductivity; at the same time, the rigid aromatic structure of the sulfide bond is lost, which enhances the main chain, and the material's high-temperature creep resistance is greatly weakened, resulting in a significant decrease in mechanical strength, highlighting the key role of the sulfide bond in performance regulation.

[0151] Compared with Example 3, the ion conductivity and mechanical strength of Comparative Example 3 both decreased significantly, and the performance stability was poor. Mechanistically, the boron-nitrogen doped graphene in this comparative example was not modified by silane, and the surface lacked amino functional groups, so it could not form stable hydrogen bonding with the modified polyaryletherketone matrix and polybenzimidazole. The fillers easily agglomerated due to van der Waals forces. The agglomerated fillers not only failed to build a continuous ion transport channel, but also blocked some of the original channels, resulting in a decrease in conductivity. At the same time, the interface bonding between the agglomerates and the matrix was weak, and stress concentration was easily formed under stress, resulting in a decrease in mechanical strength, and the performance fluctuated greatly due to uneven dispersion.

[0152] Compared with Example 3, the elongation at break of Comparative Example 4 decreased significantly, and the mechanical strength, especially the high-temperature mechanical strength, decreased significantly. Mechanistically, this comparative example did not add polybenzimidazole nitrogen-containing heterocyclic toughener, and the imidazole ring could form multiple hydrogen bonds with the matrix, improving the interfacial compatibility and enhancing the toughness of the material. After the absence of the toughener, the interfacial bonding between the matrix and the filler was weakened, and the flexible connection between the molecular chains was insufficient, resulting in poor material toughness and a sharp decrease in elongation at break. In a high-temperature environment, the interface defects are more likely to expand, and the overall structural stability of the material decreases, resulting in a significant decrease in mechanical strength.

[0153] Compared with Example 3, the ion conductivity and mechanical strength of Comparative Example 5 both decreased slightly, and the film layer was prone to have subtle defects. The key mechanism lies in the fact that this comparative example does not use gradient heat treatment, but single-temperature long-time drying: the absence of low-temperature stage leads to rapid solvent evaporation, forming defects such as pores and cracks in the film layer. These defects will destroy the continuity of the ion transport channel, while reducing the material structure density. The absence of medium-temperature interface fusion and high-temperature structure curing makes the interface bonding between the filler and the matrix insufficient, and the residual stress in the film is not effectively eliminated, ultimately leading to a decrease in conductivity due to channel defects, and a decrease in mechanical strength due to insufficient structure density.

[0154] Compared with Example 3, the high-temperature mechanical strength of Comparative Example 6 decreased sharply, the ion conductivity decreased significantly, and the thermal stability also deteriorated significantly. Mechanistically, this comparative example uses polyethylene oxide (PEO) to replace the modified polyaryletherketone matrix, and PEO has a low melting point and poor thermal stability, which will melt at high temperatures, resulting in a sharp decrease in mechanical strength of the material. After melting, the PEO molecular chain is excessively disordered, destroying the coordination environment for lithium ion transport, resulting in a significant decrease in ion conductivity. At the same time, the thermal decomposition temperature of PEO is much lower than that of polyaryletherketone, resulting in a significant deterioration in the overall thermal stability of the material, which completely fails to meet the use requirements of high-temperature solid-state batteries.

[0155] The above examples and comparative examples show that the comprehensive performance of the high-temperature-resistant solid-state battery polymer electrolyte composite depends on the optimal matching of each component and the key preparation process: the amount of modified polyarylene ether ketone matrix, the amount of introduced sulfide bond, and the amount of modified boron-nitrogen-doped graphene need to be adapted; the toughening effect of polybenzimidazole, the improvement of filler dispersion by silane modification, and the optimization of film structure by gradient heat treatment are all indispensable, and the "O-S synergistic coordination" system constructed by the sulfide bond is the core that balances high-temperature ionic conductivity and mechanical strength; the traditional polyethylene oxide matrix cannot meet the high-temperature resistance requirement, and the present application can achieve performance balance in a wide temperature range.

[0156] The above description is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A high-temperature-resistant solid-state battery polymer electrolyte composite, characterized by, The components include the following weight parts: The modified polyaryletherketone matrix: 40-60 parts; Lithium salt: 15-25 parts; Nitrogen-containing heterocyclic rigid toughening agent: 10-20 parts, polybenzimidazole; Modified boron-nitrogen-doped graphene nanoparticles: 5-15 parts; The preparation process of the high-temperature-resistant solid-state battery polymer electrolyte composite material includes the following steps: S1: Preparation of key functional components: S101: Mix 1,4-hydroquinone, 4,4'-dichlorodiphenyl sulfone, 4,4'-dimercaptodiphenyl sulfide, and anhydrous potassium carbonate, add N,N-dimethylacetamide and toluene mixed solvent, pass nitrogen, warm up to 140℃ reflux for 4h, warm up to 160-170℃ reaction for 8-10h, cool down, pour into deionized water, ethanol washing, vacuum drying, 180℃ vacuum annealing, to get the modified polyaryletherketone matrix, wherein the mass ratio of N,N-dimethylacetamide and toluene is 3:1; S102: Dissolve citric acid, boric acid and urea, ultrasonic treatment for 30min, 180℃ reaction for 12h, cool down to room temperature, dialysis, vacuum drying, immerse in 3-aminopropyl triethoxysilane reagent hydrolysate, ethanol washing, vacuum drying, to get modified boron-nitrogen-doped graphene nanoparticles; S2: Preparation of precursor solution: Take the modified polyaryletherketone matrix by proportion, add N-methyl pyrrolidone solvent, stir at 85℃ for 6-8h, form a transparent viscous solution with solid content of 10wt%, add polybenzimidazole powder by proportion, continue to stir at 80℃ for 4h, slowly add lithium salt solution, continue to stir at 70℃ for 2h, to get the precursor solution; S3: Dispersion and compounding of fillers: Add modified boron-nitrogen-doped graphene nanoparticles to the precursor solution, ultrasonic treatment for 30min, then transfer to 70℃ oil bath, stir for 3h, to get electrolyte casting solution; S4: Casting and heat treatment: Pour the electrolyte casting solution on a flat polytetrafluoroethylene or glass substrate, use an automatic film coater to control the wet film thickness to be 300-500μm, perform gradient heat treatment in vacuum; S5: Post-processing: After heat treatment, naturally cool down to room temperature, peel off the self-supporting composite material from the substrate, according to needs, punch into the required shape, place in an argon-filled glove box for use. 2.The high-temperature-resistant solid-state battery polymer electrolyte composite material according to claim 1, characterized in that, The lithium salt is one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium hexafluorophosphate, with purity ≥99.9%. 3.The high-temperature-resistant solid-state battery polymer electrolyte composite material according to claim 1, characterized in that, The purity of the nitrogen-containing heterocyclic rigid toughening agent is ≥98%. 4.The high-temperature-resistant solid-state battery polymer electrolyte composite material of claim 1, wherein, The preparation method of the lithium salt solution in S2 is: add lithium salt into N-methyl pyrrolidone solvent by proportion, stir and dissolve at room temperature, to get the lithium salt solution. 5.The high-temperature-resistant solid-state battery polymer electrolyte composite material according to claim 1, characterized in that, The specific parameters of ultrasonic treatment in S3 are: power 500W, work 2s, stop 2s, total time 30min. 6.The high-temperature-resistant solid-state battery polymer electrolyte composite material according to claim 1, characterized in that, The specific parameters of gradient heat treatment in S4 are: first vacuum drying at 80℃ for 12h, then vacuum drying at 120℃ for 6h, finally vacuum drying at 150℃ for 2h.

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