Solid-state electrolyte material and method for producing the same

Abstract

The application discloses a solid electrolyte material and a preparation method thereof, relates to the technical field of electrolyte materials, and can be applied to lithium-air batteries and lithium metal batteries. The electrolyte material takes a polymer matrix and a modified ionic liquid as core raw materials, the modified ionic liquid is prepared through non-covalent bond interaction of an ionic liquid, ion transmission enhancement fillers and a dopant at a specific ratio, and the ion transmission enhancement fillers are prepared by reacting organic ligands and metal salts at a specific ratio. The material is prepared by first preparing the modified ionic liquid through a solution reaction, then mixing the modified ionic liquid with the polymer matrix in chloroform, ultrasonicating and drying to obtain a finished product. Through the synergistic effect of the components, the solid electrolyte material effectively improves key performances such as ion conductivity and lithium ion transference number, simultaneously improves the discharge specific capacity and cycle capacity retention rate of the battery, and improves the safety performance of the battery.

Description

Technical Field

[0001] This application relates to the technical field of electrolyte materials, and in particular to a solid electrolyte material and its preparation method. Background Technology

[0002] In the rapid iteration of new energy storage technologies, lithium-air batteries, with their unique electrode structure and reaction mechanism, have become an important direction for breaking through the energy density bottleneck of traditional lithium-ion batteries. Using metallic lithium as the negative electrode active material, they directly utilize oxygen from the ambient air as the source of the positive electrode reaction, eliminating the need for encapsulating large amounts of positive electrode active material inside the battery. Combined with a lightweight, porous positive electrode carrier, they can significantly reduce the overall battery weight while achieving energy storage capabilities far exceeding those of conventional lithium-ion batteries, showing broad application prospects in portable electronic devices, long-range transportation vehicles, and distributed energy storage equipment. Currently, most research and development of lithium-air batteries relies on traditional organic liquid electrolyte systems. While these systems have a certain foundation in ion transport efficiency and lithium-ion migration capabilities, providing basic ion conduction conditions for the initial electrochemical reaction, they still suffer from many unavoidable defects during actual operation. Organic liquid electrolytes themselves have weak chemical stability and are prone to decomposition, volatilization, and leakage under charge-discharge cycles and external environmental influences. This not only continuously depletes the battery's effective components but also reduces the overall safety of the system, making it difficult to meet the requirements for long-term stable use. Meanwhile, uneven deposition can easily occur in lithium metal anodes during repeated charging and discharging, leading to the formation of lithium dendrite structures. The continuous growth of dendrites may penetrate the isolation layer, causing direct contact between the positive and negative electrodes and triggering a short circuit. This can then induce thermal runaway, combustion, or even explosion, posing safety hazards and severely restricting the transition of lithium-air batteries from laboratory research to practical industrial applications.

[0003] To address the instability and safety risks associated with organic liquid electrolytes, and to effectively protect the lithium anode, the industry is increasingly shifting its research focus to solid-state electrolyte systems. Solid-state electrolytes, existing in a solid form, lack fluidity and volatility, and can structurally suppress electrolyte leakage and side reactions. Their inherent mechanical strength physically inhibits lithium dendrite growth and puncture, improving the battery's safety margin and service life under complex operating conditions. Compared to traditional liquid systems, solid-state electrolytes can create more stable interfaces, reducing interfacial side reactions and impedance proliferation, maintaining the reversibility and consistency of electrochemical reactions, and can be adapted to higher voltage electrode materials, further unlocking the energy density potential of lithium-air batteries.

[0004] With the market demand for high-safety, high-energy-density, and long-life energy storage devices continuing to increase, traditional organic liquid electrolytes are no longer sufficient to meet the comprehensive performance requirements of lithium-air batteries in practical scenarios. There is an urgent need to develop new solid-state electrolytes with high comprehensive performance to replace existing liquid systems and solve core issues such as stability, safety, and cycle reliability. To meet these needs, the designed solid-state electrolyte must be geared towards applications such as high-altitude, long-endurance unmanned aerial vehicles (UAVs). These devices operate under conditions of thin oxygen at high altitudes, wide temperature variations, continuous charging and discharging, and lightweight constraints. This requires the battery to maintain excellent performance during continuous operation to ensure stable power output, long endurance, and operational safety for UAVs during long-distance cruises, complex weather conditions, and uninterrupted charge-discharge cycles. Summary of the Invention

[0005] The purpose of this application is to provide a solid electrolyte material with excellent ionic conductivity, lithium-ion transference number, discharge specific capacity, and capacity retention after charge-discharge cycles, thereby extending the service life of the solid electrolyte material.

[0006] Firstly, this application provides a solid electrolyte material and its preparation method, which adopts the following technical solution: A solid electrolyte material comprises the following raw materials in parts by weight: 7-40 parts polymer matrix and 5-8 parts modified ionic liquid; the modified ionic liquid comprises an ionic liquid, an ion transport enhancing filler, and a dopant; the mass ratio of the ionic liquid, the ion transport enhancing filler, and the dopant is 1:(0.95-1.25):(0.05-0.12), and the ion transport enhancing filler is prepared by coordination reaction of an organic ligand and a metal salt.

[0007] By adopting the above technical solution, the solid electrolyte material is composed of a polymer matrix and a modified ionic liquid in a reasonable ratio. It can take into account the mechanical stability, film-forming properties and interfacial compatibility of the polymer matrix. At the same time, by taking advantage of the high ion conductivity of the modified ionic liquid, the overall ion transport efficiency is significantly improved, the interfacial impedance is reduced, the contact state between the electrode and the electrolyte is improved, the occurrence of side reactions is suppressed, the cycle stability and safety performance of the battery are improved, and the synergistic optimization of mechanical and electrochemical performance is achieved. The modified ionic liquid is prepared by combining ionic liquid, ion transport enhancement filler and dopant through non-covalent interactions. This allows the components to be uniformly combined and work synergistically at the molecular level. The ion transport enhancement filler can build continuous fast ion transport channels and reduce the activation energy of ion migration. The dopant can promote ion dissociation, optimize the ion coordination environment, and increase ion transference number and conductivity. The non-covalent interaction can maintain the intrinsic high conductivity and thermal stability of the ionic liquid, avoid the ion transport obstruction caused by covalent cross-linking, improve the structural stability and component compatibility of the structure, reduce the risk of phase separation and leakage, and broaden the electrochemical stability window. The modified ionic liquid has high ion conductivity, structural stability and interfacial compatibility, providing a stable and efficient ion conduction environment for solid electrolytes and meeting the long-term stable operation requirements of solid batteries.

[0008] Optionally, the ionic liquid is any one or more of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-vinyl-2,3-dimethylimidazolium trifluoromethanesulfonate.

[0009] By adopting the above technical solution and selecting ionic liquids with vinyl functional groups, multiple positive effects can be achieved in solid-state electrolyte systems. Vinyl groups, as active reaction sites, can participate in appropriate cross-linking or polymerization reactions within the system, leading to stronger interactions between the ionic liquid and the polymer matrix. This improves interfacial compatibility and structural stability, effectively alleviating problems such as phase separation, leakage, and high interfacial impedance that are common with traditional ionic liquids. Simultaneously, it enhances the overall mechanical strength and structural integrity of the solid-state electrolyte, making it less prone to damage during cycling and improving battery service stability. Vinyl functional groups, without significantly impairing the intrinsic ion conductivity of the ionic liquid, help construct more continuous and stable ion transport channels, reducing ion transport resistance at the interface and improving ion migration efficiency and conductivity. Furthermore, the presence of vinyl groups can optimize the interfacial contact between the electrolyte and the electrode, suppress interfacial side reactions, broaden the electrochemical stability window of the system, and improve the thermal and chemical stability of the material. This allows the solid-state electrolyte to maintain stable electrochemical performance under different operating conditions, balancing high ion conductivity, good mechanical properties, and excellent interfacial stability.

[0010] Optionally, the dopant is any one or more of tetramethylammonium cation, methyltriethylammonium cation, and 1-methyl-3-methylimidazolium cation.

[0011] By employing the above-mentioned technical solutions, using tetramethylammonium cations, methyltriethylammonium cations, and 1-methyl-3-methylimidazolium cations as dopants, multiple functions can be achieved in solid-state electrolyte systems, including efficient dissociation promotion, enhanced conductivity, and structural stabilization. These cations have symmetrical structures and uniform charge distribution, which can effectively disrupt ion association within ionic liquids, thereby improving ionic conductivity and ion migration efficiency. Simultaneously, these cations have moderate size and strong diffusion capabilities, enabling synergistic migration within ion transport channels, reducing the activation energy of ion transport, and facilitating smoother ion conduction. They exhibit good compatibility with polymer matrices, modified ionic liquids, and fillers, reducing interfacial defects and phase separation, improving the overall structural uniformity and mechanical stability of the electrolyte, suppressing side reactions, and optimizing the electrochemical stability window. Furthermore, these cations are chemically stable and do not readily undergo side reactions, maintaining the performance stability of the electrolyte during long-term cycling. This allows the solid-state electrolyte to possess high ion conductivity, excellent interfacial compatibility, and reliable chemical stability, better meeting the requirements for efficient and stable operation of solid-state batteries.

[0012] Optionally, the preparation method of the modified ionic liquid includes the following steps: S1. Dissolve 2,5-dihydroxyterephthalic acid, 1,2-di(4-pyridyl)ethylene, nickel nitrate hexahydrate, and cobalt nitrate hexahydrate in N,N-dimethylformamide, heat, stir, centrifuge, filter to obtain solid, wash, and dry to obtain ion transport enhanced packing. S2. Dissolve the ionic liquid in anhydrous ethanol, add the ion transport enhancement filler and dopant prepared in step S1, heat, stir, centrifuge, filter to obtain a solid, wash, dry, and obtain the modified ionic liquid.

[0013] By employing the above technical solution, this preparation method first prepares the ion transport enhancement filler through steps such as solution heating and stirring, centrifugation and filtration. This ensures the raw materials react fully, forming a filler product with a regular structure and stable performance. Simultaneously, washing and drying remove impurities, ensuring the purity of the filler and laying the foundation for the subsequent construction of ion transport channels. Subsequently, the ionic liquid, the prepared filler, and the dopant are mixed and reacted in anhydrous ethanol. The anhydrous environment avoids the interference of water on the performance of the ionic liquid and the interactions between components. Heating and stirring promote the uniform dispersion of each component, allowing the dopant to fully exert its dissociation-promoting effect, and enabling the ion transport enhancement filler and ionic liquid to bind tightly through non-covalent bonds. The entire preparation process is simple to operate and operates under mild conditions, effectively avoiding the damage to the raw material structure caused by extreme conditions such as high temperature and high pressure. Furthermore, the centrifugation, filtration, washing, and drying steps further improve the purity of the modified ionic liquid, reducing the impact of impurities on ion conduction, ultimately yielding a modified ionic liquid with uniform dispersion, stable structure, and high ion conduction efficiency.

[0014] Optionally, in step S1, the mass ratio of 2,5-dihydroxyterephthalic acid, 1,2-bis(4-pyridyl)ethylene, nickel nitrate hexahydrate, and cobalt nitrate hexahydrate is 1:1:(1.8-2.5):(0.6-0.8).

[0015] By adopting the above technical solution, step S1 uses a specific mass ratio to prepare the ion transport enhancement filler, ensuring the synergistic effect and full reaction of each raw material, guaranteeing a regular filler structure and stable performance. This ratio enables precise coordination between organic ligands and metal ions, forming a filler structure with uniform pore size and suitable specific surface area, providing a smooth channel for subsequent ion transport. Simultaneously, a reasonable ratio avoids structural defects caused by excessive amounts of a single raw material and prevents insufficient coordination due to insufficient raw materials, ensuring good dispersibility and stability of the filler. Based on this, when the filler is subsequently mixed with ionic liquids and dopants, it can better leverage its ion transport enhancement effect through non-covalent bonding. The entire preparation process is simple to operate and operates under mild conditions, effectively avoiding damage to the raw material structure caused by extreme conditions such as high temperature and high pressure. Furthermore, centrifugal filtration and washing / drying steps further improve the purity of the modified ionic liquid, reducing the impact of impurities on ion conduction, ultimately yielding a modified ionic liquid with uniform dispersion, stable structure, and high ion conduction efficiency, suitable for the needs of solid electrolytes.

[0016] Optionally, in step S1, the stirring rate is 400-800 rpm and the stirring time is 22-30 h.

[0017] By adopting the above technical solution, the stirring rate can fully disperse the raw materials in the solvent without generating excessive turbulence, ensuring uniform contact between the organic ligands and metal ions, which is conducive to forming a coordination structure with uniform structure and few defects. The appropriate stirring time can ensure that the coordination reaction proceeds fully, obtaining ion transport enhanced filler with excellent crystallinity and stability, while avoiding structural damage or agglomeration caused by excessive stirring time, thereby improving the purity and ion transport performance of the filler and providing a foundation for the subsequent preparation of modified ionic liquids.

[0018] Optionally, the polymer substrate is any one of polyvinylidene fluoride, polyacrylonitrile, and polymethyl methacrylate.

[0019] By adopting the above technical solutions, polyvinylidene fluoride, polyacrylonitrile, and polymethyl methacrylate (PMMA) are all suitable for the preparation of solid-state electrolytes. All three possess good film-forming properties and mechanical strength, enabling the formation of a complete and stable electrolyte membrane. They also exhibit excellent chemical stability, good compatibility with modified ionic liquids, and reduced phase separation. Furthermore, they can synergistically work with ion transport-enhancing fillers and dopants without hindering ion conduction, and can improve the interfacial compatibility between the electrolyte and the electrode, ensuring the structural stability and electrochemical performance of the solid-state electrolyte, making it suitable for use in solid-state batteries.

[0020] Secondly, the preparation method of the solid electrolyte material provided in this application adopts the following technical solution: A method for preparing a solid electrolyte material includes the following steps: The modified ionic liquid was dissolved in chloroform and stirred. The polymer matrix was then added, sonicated, stirred, and vacuum dried to obtain a solid electrolyte material.

[0021] By employing the above technical solution, this method prepares the modified ionic liquid and polymer matrix together, achieving full fusion and uniform dispersion of the two, effectively avoiding stratification or phase separation problems. First, the modified ionic liquid is dissolved in chloroform and stirred for dispersion, then the polymer matrix is ​​added. Ultrasonication promotes molecular-level interactions, and subsequent stirring further enhances the system's homogeneity. Vacuum drying removes the solvent while simultaneously promoting the formation of a stable composite structure. This retains the high ionic conductivity of the modified ionic liquid while leveraging the film-forming properties and mechanical strength of the polymer matrix to form a structurally complete electrolyte membrane, improving interfacial compatibility and electrochemical performance stability, making it suitable for use in solid-state batteries.

[0022] Optionally, the modified ionic liquid and polymer matrix have a mass fraction of 4-9% in chloroform.

[0023] By employing the above technical solution, the mass fractions of the modified ionic liquid and polymer matrix in chloroform are controlled within a suitable range, ensuring their complete dissolution and uniform dispersion. This avoids excessively high concentrations leading to viscous and uneven mixing, or excessively low concentrations affecting subsequent film formation. This range allows the ultrasonic and stirring processes to more easily promote molecular-level stabilization, resulting in a dense electrolyte film without significant defects after vacuum drying. This film balances good mechanical strength and ion conductivity while reducing solvent residue, ensuring stable electrochemical performance of the electrolyte and making it suitable for solid-state batteries.

[0024] Application of a solid electrolyte material in lithium-air batteries and lithium metal batteries.

[0025] In summary, this application includes at least one of the following beneficial technical effects: 1. Compared with existing technologies, the modified ionic liquid in this application is prepared by compounding ionic liquid, ion transport enhancement filler and dopant in a specific mass ratio and through non-covalent interactions. The components can be uniformly combined and synergistically act at the molecular level. The ion transport enhancement filler can construct continuous fast ion transport channels, the dopant can effectively promote ion dissociation and optimize the coordination environment, and the non-covalent interactions ensure the intrinsic conductivity and thermal stability of the ionic liquid. At the same time, it improves the structural stability and component compatibility of the system, significantly improves the ionic conductivity and lithium-ion transference number of the solid electrolyte, and can also broaden the electrochemical stability window and reduce the risk of phase separation. 2. Compared with existing technologies, this application prepares a solid electrolyte by mixing modified ionic liquid and polymer matrix in a reasonable ratio, which can achieve full fusion and uniform dispersion at the molecular level, effectively avoiding phase separation or delamination problems. It retains the high ionic conductivity of the modified ionic liquid while relying on the good film-forming properties and mechanical strength of the polymer matrix to form a structurally complete electrolyte film. This improves the interfacial compatibility between the electrolyte and the electrode, reduces interfacial side reactions and impedance proliferation, and simultaneously enhances the mechanical strength of the electrolyte, inhibiting lithium dendrite growth and significantly improving the battery's discharge specific capacity and cycle capacity retention. Detailed Implementation

[0026] Unless otherwise specified, all raw materials used in the embodiments and comparative examples of this application are commercially available products: Polyvinylidene fluoride, item number: V30214-500g, source: Yuanye. Example 1

[0027] A method for preparing a solid electrolyte material includes the following steps: The preparation method of modified ionic liquids includes the following steps: 5 g of 2,5-dihydroxyterephthalic acid, 5 g of 1,2-bis(4-pyridyl)ethylene, 11 g of nickel nitrate hexahydrate, and 3.5 g of cobalt nitrate hexahydrate were dissolved in 500 mL of N,N-dimethylformamide. The solution was heated to 85 °C and stirred at 500 rpm for 40 min to obtain the first mixture. The first mixture was centrifuged at 8000 rpm for 15 min, filtered, and the supernatant was discarded to obtain the first solid. The first solid was immersed in 300 mL of N,N-dimethylformamide and washed for 24 h. The N,N-dimethylformamide was replaced every 12 h for a total of 2 times. The first solid after the second N,N-dimethylformamide soaking was removed and immersed in 400 mL of anhydrous methanol for 48 h. The anhydrous methanol was replaced every 12 h for a total of 4 times. The first solid after the final anhydrous methanol soaking was removed and dried in a vacuum drying oven at 100 °C and 0.08 MPa for 12 h to obtain the ion transport enhanced packing. 10 g of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt was dissolved in 30 mL of anhydrous ethanol and stirred at 500 rpm for 10 min to obtain a second mixture. 9.5 g of ion transport enhancing filler and 0.5 g of methyltriethylammonium cation were added to the second mixture, and the mixture was heated to 60 °C and stirred at 500 rpm for 24 h to obtain a third mixture. The third mixture was centrifuged at 6000 rpm for 5 min, filtered to obtain a second solid, and washed twice with 200 mL of ethanol. After each wash, the solid was centrifuged at 4000 rpm for 5 min, and the ethanol was discarded. The washed third solid was dried at 80 °C and 0.08 MPa vacuum for 12 h to obtain a modified ionic liquid.

[0028] 5g of modified ionic liquid was dissolved in 150mL of chloroform and stirred at 500rpm for 30min to obtain a fourth mixture. 10g of polyvinylidene fluoride was added to the fourth mixture, and the mixture was sonicated at 1000W for 8min, then stirred at 500rpm for 10min. The mixture was then dried at 0.09MPa vacuum and 85℃ for 24h to obtain a solid electrolyte material. Example 2

[0029] The difference between Example 2 and Example 1 is that 10g of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt, 9.5g of ion transport enhancement filler, and 0.5g of methyltriethylammonium cation in Example 1 are replaced with 10g of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt, 10.5g of ion transport enhancement filler, and 0.8g of methyltriethylammonium cation. Example 3

[0030] The difference between Example 3 and Example 1 is that 10g of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt, 9.5g of ion transport enhancement filler, and 0.5g of methyltriethylammonium cation in Example 1 are replaced with 10g of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt, 11.5g of ion transport enhancement filler, and 1g of methyltriethylammonium cation. Example 4

[0031] The difference between Example 4 and Example 1 is that 10g of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt, 9.5g of ion transport enhancing filler, and 0.5g of methyltriethylammonium cation in Example 1 are replaced with 10g of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt, 12.5g of ion transport enhancing filler, and 1.2g of methyltriethylammonium cation. Example 5

[0032] The difference between Example 5 and Example 3 is that the 5g modified ionic liquid, 150mL chloroform, and 10g polyvinylidene fluoride in Example 3 are replaced with 6.5g modified ionic liquid, 350mL chloroform, and 25g polyvinylidene fluoride. Example 6

[0033] The difference between Example 6 and Example 3 is that the 5g modified ionic liquid, 150mL chloroform, and 10g polyvinylidene fluoride in Example 3 are replaced with 8g modified ionic liquid, 550mL chloroform, and 40g polyvinylidene fluoride. Comparative Example 1

[0034] The difference between Comparative Example 1 and Example 1 is that 10g of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt, 9.5g of ion transport enhancing filler, and 0.5g of methyltriethylammonium cation in Example 1 are replaced with 12g of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt, 8.5g of ion transport enhancing filler, and 0.5g of methyltriethylammonium cation. Comparative Example 2

[0035] The difference between Comparative Example 2 and Example 3 is that the 5g modified ionic liquid, 150mL chloroform, and 10g polyvinylidene fluoride in Example 3 are replaced with 4g modified ionic liquid, 280mL chloroform, and 20g polyvinylidene fluoride. Comparative Example 3

[0036] The difference between Comparative Example 3 and Example 5 is that 10g of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt was replaced with 10g of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt. Test case

[0037] The solid electrolytes prepared in Examples 1-6 and Comparative Examples 1-3 were applied to batteries, and their performance was tested. Batteries were assembled in a glove box. Treated nickel foam was used as the positive electrode, and the solid electrolyte material was used as the electrolyte. 0.1 mL of a 1M solution of lithium bis(trifluoromethanesulfonyl)imide and tetraethylene glycol dimethyl ether (1:1 volume ratio) was added, followed by the addition of a lithium sheet as the negative electrode, and the batteries were assembled. The batteries were activated in an oven (65°C, 12 h, argon atmosphere), then removed and placed in an oxygen chamber for testing using the Wuhan Landian testing system. Ionic conductivity and lithium-ion transport number were tested. The first discharge specific capacity and cycle stability were also tested after assembling the solid electrolyte into a lithium-air battery. The test results are shown in Table 1.

[0038]

[0039] A comparative analysis of Examples 1-4 and Comparative Example 1 revealed that the solid electrolyte prepared in Example 3 exhibited the best overall performance. The difference in performance may be attributed to variations in the mass ratios of the ionic liquid, ion transport enhancement filler, and dopant. Specifically, the amounts of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt, ion transport enhancement filler, and methyltriethylammonium cation differ. 1-Vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt, as the matrix ionic liquid, provides the basic ion transport carrier for the electrolyte. Its amount needs to be matched with the ion transport enhancement filler and methyltriethylammonium cation to construct efficient ion transport channels. The ion transport enhancement filler can construct a three-dimensional network structure, increasing the ion transport contact area and reducing ion transport resistance. However, more filler is not always better; excessive filler can lead to agglomeration, disrupting matrix continuity and hindering ion migration; insufficient filler will fail to form a complete transport network, resulting in low ion transport efficiency. Methyltriethylammonium cations, as dopants, can regulate the arrangement of imidazole cations in ionic liquids, reduce the interaction between lithium ions and imidazole rings, and enhance the degree of freedom of lithium ion migration. Appropriate doping optimizes ion transport kinetics, while excessive doping increases inter-ion interference and reduces ion migration rates. Insufficient doping fails to fully exert its regulatory effect. When the amounts of these three components are properly matched, they work synergistically. The ionic liquid can fully wet the filler surface, forming a continuous ion transport path. The dopants effectively regulate the ionic environment, improving ionic conductivity and lithium ion transference number, enhancing the interfacial compatibility between the electrolyte and electrode, reducing interfacial side reactions during charging and discharging, and improving the battery's initial discharge specific capacity and cycle stability. Imbalanced doping amounts, however, can disrupt the integrity of the transport network, the harmony of the ionic environment, or interfacial stability, leading to a decline in various performance characteristics.

[0040] Comparative analysis of Examples 5-6 and Comparative Example 2 revealed that the solid electrolyte prepared in Example 5 exhibited the best overall performance. The reason for this performance difference may lie in the varying amounts of polymer matrix and modified ionic liquid used in the preparation of the solid electrolyte. The ratio of modified ionic liquid to polyvinylidene fluoride (PVDF) directly determines the microstructure and ion transport environment of the solid electrolyte. When the content of modified ionic liquid is moderately increased, continuous and stable ion transport channels can be constructed within PVDF, reducing the lithium-ion transition barrier. Simultaneously, its surface functional sites synergistically inhibit anion migration and increase the lithium-ion transference number. Sufficient ion transport sites and continuous channels significantly improve ionic conductivity, providing an efficient ion transport environment for lithium-air batteries, thereby enhancing the discharge specific capacity. A moderate polymer matrix content ensures both the mechanical stability and interfacial compatibility of the electrolyte without compromising its performance. Excessive polyvinylidene fluoride (PVDF) can obstruct ion transport pathways, but excessive ionic liquid will not cause structural loosening or increased side reactions. The synergistic optimization of the two can form an electrolyte system with both high ion conductivity and structural stability, reducing structural damage and interface degradation during charge and discharge, thereby significantly improving capacity retention after 200 cycles. If the modified ionic liquid is insufficient, the ion transport channels will be discontinuous, and the conductivity and transference number will be low. If the polymer matrix ratio is unbalanced, it will damage the ion transport network or reduce mechanical properties, resulting in a decline in overall performance. Only when the amounts of the two are matched can the synergistic optimization of ion conductivity, lithium-ion transference number, discharge specific capacity and cycle stability be achieved.

[0041] Comparative analysis of Example 5 and Comparative Example 3 revealed that the solid electrolyte prepared in Example 5 exhibited the best overall performance. The difference in performance may be attributed to the use of different ionic liquids. The 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt and the 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt differ in alkyl chain length and double bond substitution in their cationic structures. The former, containing vinyl groups, forms weak interactions with the system and arranges itself in a regular pattern, lowering the ion transport barrier and increasing ionic conductivity. The shorter ethyl chain reduces steric hindrance, facilitating lithium-ion dissociation and migration, and increasing the lithium-ion transference number. This ionic liquid shows better compatibility with ion transport enhancement fillers and methyltriethylammonium cations, enabling the construction of continuous and efficient ion transport channels. This results in more complete reactions in lithium-air batteries and a higher initial discharge specific capacity. Simultaneously, it stabilizes the electrode interface, suppresses side reactions and structural degradation, reduces performance degradation during charge and discharge processes, and thus improves capacity retention after long-term cycling.

[0042] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made to the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A solid state electrolyte material, characterized by, The solid-state electrolyte material comprises the following raw materials by weight: 7-40 parts of a polymer matrix, 5-8 parts of a modified ionic liquid; the modified ionic liquid comprises an ionic liquid, an ion transport enhancing filler, and a dopant; the mass ratio of the ionic liquid, the ion transport enhancing filler, and the dopant is 1:(0.95-1.25):(0.05-0.12); the ion transport enhancing filler is prepared by coordination reaction of an organic ligand and a metal salt.

2. The solid-state electrolyte material of claim 1, wherein, The ionic liquid is any one or more of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-vinyl-3-ethylimidazolium bis(trifluoromethylsulfonyl)imide, and 1-vinyl-2,3-dimethylimidazolium trifluoromethanesulfonate.

3. The solid-state electrolyte material of claim 1, wherein, The dopant is any one or more of a tetramethylammonium cation, a methyltriethylammonium cation, and a 1-methyl-3-methylimidazolium cation.

4. The solid-state electrolyte material of claim 1, wherein, The preparation method of the modified ionic liquid comprises the following steps: S1. Dissolving 2,5-dihydroxyterephthalic acid, 1,2-di(4-pyridyl)ethylene, nickel nitrate hexahydrate, and cobalt nitrate hexahydrate in N,N-dimethylformamide, heating, stirring, centrifuging, filtering to obtain a solid, washing, and drying to obtain the ion transport enhancing filler; S2. Dissolving the ionic liquid in anhydrous ethanol, adding the ion transport enhancing filler prepared in step S1 and the dopant, heating, stirring, centrifuging, filtering to obtain a solid, washing, and drying to obtain the modified ionic liquid.

5. The solid-state electrolyte material of claim 4, wherein, The mass ratio of 2,5-dihydroxyterephthalic acid, 1,2-di(4-pyridyl)ethylene, nickel nitrate hexahydrate, and cobalt nitrate hexahydrate in step S1 is 1:1:(1.8-2.5):(0.6-0.8).

6. The solid-state electrolyte material of claim 4, wherein, The stirring rate in step S1 is 400-800 rpm, and the stirring time is 22-30 h.

7. The solid-state electrolyte material of claim 1, wherein, The polymer matrix is any one of polyvinylidene fluoride, polyacrylonitrile, and polymethyl methacrylate.

8. A method of producing a solid-state electrolyte material, characterized by, The method comprises the following steps: dissolving the modified ionic liquid in chloroform, stirring, adding the polymer matrix, ultrasonically treating, stirring, and vacuum drying to obtain the solid-state electrolyte material.

9. The method of claim 8, wherein the solid-state electrolyte material is prepared by a method comprising: The mass fraction of the modified ionic liquid and the polymer matrix in chloroform is 4-9%.

10. Application of the solid-state electrolyte material according to any one of claims 1-7 in a lithium-air battery or a lithium metal battery.

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