A gel polymer electrolyte membrane in an energy storage system and a preparation method and application thereof

Abstract

This invention belongs to the technical field of lithium battery polymer electrolyte membrane materials, and discloses a gel polymer electrolyte membrane for energy storage systems, its preparation method, and its application. The method includes: adding lithium carbonate to a 2-acrylamido-2-methylpropanesulfonic acid solution; after the reaction is complete, evaporation to obtain lithium 2-acrylamido-2-methylpropanesulfonate; mixing lithium 2-acrylamido-2-methylpropanesulfonate, glycidyl methacrylate, and polyethylene glycol monomethyl ether acrylate; adding a crosslinking agent, plasticizer, and deionized water; stirring until completely dissolved to obtain a prepolymer solution; adding an initiator to the prepolymer solution; stirring evenly; pouring the mixture into a mold; and reacting in a constant temperature water bath to form a gel polymer electrolyte; removing the gel polymer electrolyte from the mold and drying it to obtain a gel polymer electrolyte membrane. This invention, based on the reaction mechanism of multi-component monomer copolymerization, significantly improves both rate capability and cycle performance, meeting the energy storage requirements of high-performance lithium batteries.

Description

Technical Field

[0001] This invention belongs to the technical field of lithium battery polymer electrolyte membrane materials, and relates to a gel polymer electrolyte membrane in an energy storage system, its preparation method and application. Background Technology

[0002] With the increasing global emphasis on clean and sustainable energy utilization, lithium batteries have been widely used in many fields such as electric vehicles, portable electronic devices, and energy storage power stations due to their advantages such as high energy density, long cycle life, and no memory effect, becoming one of the key technologies for modern energy storage and conversion.

[0003] Among the performance indicators of lithium batteries, energy density, power density, cycle life, and safety are key factors in evaluating their performance. Gel polymer electrolytes, as an important component of lithium batteries, play a crucial role in the overall battery performance. They not only need excellent ion conductivity to ensure efficient lithium-ion transport between the positive and negative electrodes, enabling rapid charging and discharging, but also sufficient mechanical support to maintain the stability of the battery's internal structure, preventing poor physical contact between the electrodes and the electrolyte, and structural damage caused by volume changes during charging and discharging. Furthermore, good interfacial stability and a high lithium-ion transference number are also key to improving battery performance.

[0004] Currently, the matrix material of gel polymer electrolytes is modified by introducing new polymer monomers or additives to improve their ionic conductivity and mechanical properties. Optimizing the preparation process of gel polymer electrolytes, such as using different polymerization methods and controlling polymerization reaction conditions, can improve the electrolyte's microstructure and properties. Novel gel polymer electrolyte structures, such as multilayer structures and gradient structures, are designed to achieve optimized combinations of different performance regions.

[0005] Although existing improvements have enhanced the performance of gel polymer electrolytes to some extent, they still cannot fundamentally solve problems such as insufficient ionic conductivity, low lithium-ion transference number, difficulty in balancing rate performance and cycle performance, and difficulty in balancing mechanical support performance and ion conduction performance. Summary of the Invention

[0006] The purpose of this invention is to provide a gel polymer electrolyte membrane for energy storage systems, its preparation method and application, to solve the problems of insufficient ionic conductivity, low lithium ion transference number, difficulty in achieving both rate performance and cycle performance, and difficulty in balancing mechanical support performance and ion conduction performance in the field of lithium battery energy storage.

[0007] To achieve the above objectives, the present invention employs the following technical solution: A gel polymer electrolyte membrane in an energy storage system, the polymer having the following structural formula: .

[0008] Furthermore, the room temperature ionic conductivity reaches 1.2 × 10⁻⁶. -3 S / cm.

[0009] A method for preparing a gel polymer electrolyte membrane in the energy storage system, comprising: Lithium carbonate was added to a solution of 2-acrylamido-2-methylpropanesulfonic acid. After the reaction was completed, the solution was evaporated to obtain lithium 2-acrylamido-2-methylpropanesulfonate. Lithium 2-acrylamido-2-methylpropanesulfonate, glycidyl methacrylate and polyethylene glycol monomethyl ether acrylate are mixed, and crosslinking agent, plasticizer and deionized water are added. The mixture is stirred until completely dissolved to obtain a prepolymer solution. An initiator is added to the prepolymer solution, stirred evenly, and then poured into a mold. The mixture is then reacted in a constant temperature water bath to form a gel-like polymer electrolyte. The gel polymer electrolyte is removed from the mold and dried to obtain a gel polymer electrolyte membrane.

[0010] Furthermore, the molar ratio of 2-acrylamido-2-methylpropanesulfonic acid solution to lithium carbonate is 1:1.

[0011] Furthermore, the reaction temperature of 2-acrylamido-2-methylpropanesulfonic acid solution with lithium carbonate is 55~65℃, and the reaction time is 3~5 h; The drying temperature of lithium 2-acrylamido-2-methylpropanesulfonate is 75~85℃, and the drying time is 10~14 h.

[0012] Furthermore, the mass ratio of lithium 2-acrylamido-2-methylpropanesulfonate, glycidyl methacrylate, and polyethylene glycol monomethyl ether acrylate is 2.5~3.5:1.5~2.5:1.5~2.5.

[0013] Furthermore, the crosslinking agent accounts for 1.0% to 1.5% of the total mass of lithium 2-acrylamido-2-methylpropanesulfonate, glycidyl methacrylate, and polyethylene glycol monomethyl ether acrylate. The crosslinking agent is N,N-methylenebisacrylamide; The plasticizer accounts for 30% to 40% of the total mass of lithium 2-acrylamido-2-methylpropanesulfonate, glycidyl methacrylate, and polyethylene glycol monomethyl ether acrylate. The plasticizer is a mixture of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate, with a mass ratio of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate of 0.8~1.2:0.8~1.2:0.8~1.2. The mass of deionized water is 2.0 to 3.0 times the total mass of lithium 2-acrylamido-2-methylpropanesulfonate, glycidyl methacrylate, and polyethylene glycol monomethyl ether acrylate. The mass of the initiator is 1.0% to 1.5% of the mass of the prepolymer solution; The initiator is ammonium persulfate.

[0014] Furthermore, the constant temperature water bath temperature is 60~70℃, and the reaction time is 4-6 h.

[0015] Furthermore, the drying temperature of the gel polymer electrolyte is 60~70℃, and the drying time is 18~22 h.

[0016] A lithium battery, made of the aforementioned gel polymer electrolyte membrane, has an initial discharge specific capacity of 157 mAh·g at a 0.5C rate. -1 .

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a gel polymer electrolyte membrane for energy storage systems. It forms a stable cross-linked network structure through copolymerization of functional lithium salt monomers. The molecular chain is rich in lithium active groups and ion transport sites, which ensures efficient lithium ion conduction from the structural nature. At the same time, it improves the structural stability and gel moldability of the polymer matrix, laying the foundation for the electrochemical and mechanical properties of the electrolyte membrane.

[0018] Furthermore, the electrolyte membrane exhibits a room temperature ionic conductivity of 1.2 × 10⁻⁶. - With a speed of 3 S / cm, it can significantly reduce the resistance to lithium-ion migration, accelerate the ion transport rate inside the electrolyte, effectively reduce the internal resistance of the battery, reduce polarization loss during charging and discharging, and improve the charging and discharging response speed and working stability of lithium batteries.

[0019] This invention also provides a method for preparing a gel polymer electrolyte membrane in an energy storage system. The method involves copolymerizing monomers with different functions, specifically using glycidyl methacrylate (GMA) as the supporting polymer network structure and polyethylene glycol monomethyl ether acrylate (PEGA) as the lithium-ion conduction promoter, in a copolymerization reaction with AMPSLi to form a single-ion gel polymer electrolyte membrane with both good mechanical properties and high ion conductivity. The epoxy groups in GMA form crosslinking points through ring opening, enhancing the stability of the polymer network and ensuring good mechanical support, high tensile strength, and elongation at break of the electrolyte membrane. The numerous ether oxygen bonds in PEGA effectively coordinate with lithium ions, promoting lithium ion dissociation and migration, and improving ionic conductivity and lithium-ion transference number to meet the requirements of high-frequency charge and discharge. This invention features a simple and easy-to-operate process. Based on the reaction mechanism of multi-component monomer copolymerization, performance breakthroughs are achieved through reasonable control of the proportions of each monomer and reaction conditions. The prepared gel polymer electrolyte membrane exhibits excellent overall performance, with significant improvements in both rate performance and cycle performance. It addresses the issues of low ionic conductivity, low lithium-ion transference number, poor rate and cycle performance, and the difficulty in synergistically optimizing mechanical and ion conductivity in electrolyte membranes. This membrane can meet the energy storage requirements of high-performance lithium batteries and provides core material support for high-reliability lithium battery energy storage.

[0020] Furthermore, limiting the molar ratio of 2-acrylamido-2-methylpropanesulfonic acid to lithium carbonate to 1:1 ensures the complete acid-base reaction, maximizes the synthesis of lithium salt monomer AMPSLi, avoids the introduction of impurities caused by raw material residues or incomplete reactions, ensures sufficient lithium source supply, increases the lithium ion content of the system, and avoids the negative impact of by-products on electrochemical performance.

[0021] Furthermore, by limiting the reaction temperature, time, and drying parameters for lithium salt synthesis, optimizing the monomer synthesis reaction conditions, and ensuring the full reaction and synthesis of lithium salt monomers, while precisely controlling the drying conditions, residual moisture and impurities can be effectively removed, preventing moisture from causing battery side reactions, ensuring the purity and structural stability of lithium salt monomers, and improving the effect of subsequent polymerization reactions.

[0022] Furthermore, by limiting the ratio range of the three functional monomers, the synergistic ratio of the multiple monomers can optimize the polymer network structure, take into account the flexibility of the molecular chain, the crosslinking density and the ion capacity, balance the mechanical strength and air permeability of the electrolyte membrane, improve the gel liquid retention, and further improve the lithium ion conduction environment.

[0023] Furthermore, by limiting the types, ratios, and component proportions of crosslinking agents, plasticizers, and initiators, specific crosslinking agents can form a dense and stable three-dimensional network structure, improving the mechanical strength and stability of the electrolyte membrane; composite plasticizers can enhance the fluidity of the system, improving solution capacity and ion mobility; limiting the amount of initiator ensures the stable progress of the polymerization reaction, avoiding excessive crosslinking or insufficient polymerization. The synergistic effect of multiple component parameters comprehensively optimizes the formability, electrochemical stability, and overall performance of the electrolyte membrane.

[0024] Furthermore, limiting the water bath temperature and time range of the polymerization reaction ensures that the monomers in the prepolymer solution are fully and uniformly polymerized, and the reaction conditions are mild and controllable. This avoids the system aging and deterioration due to excessively high temperatures or incomplete polymerization due to excessively low temperatures, ensuring that the gel polymer structure is uniform and dense, and improving the overall performance uniformity of the electrolyte membrane.

[0025] Furthermore, by limiting the subsequent drying parameters of the gel electrolyte, residual moisture and volatile solvents in the system can be effectively removed, the water content of the electrolyte membrane can be reduced, hydrolysis side reactions inside the lithium battery can be prevented, corrosion and capacity decay can be inhibited, and the cycle stability and long-term safety of the battery can be improved.

[0026] This invention also provides a lithium battery in which, regarding interface stability, the assembled lithium battery exhibits an initial discharge specific capacity of 157 mAh·g at a 0.5C rate. -1 This invention demonstrates the excellent interfacial compatibility between the gel polymer electrolyte membrane and the electrode material, which can fully leverage the capacity advantages of the electrode material, significantly improve the discharge capacity and energy density of lithium batteries, optimize the battery energy storage performance and practical application value, and provide a brand-new approach for high-safety, long-life semi-solid-state batteries. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 The impedance diagrams are of the electrolyte membranes of Examples 1, 4 and Comparative Example 1 after 100 cycles.

[0029] Figure 2 This is a schematic diagram showing the capacity of the electrolyte membranes of Embodiment 1 and Comparative Example 1 of the present invention at different expansion rates.

[0030] Figure 3 This is a charge-discharge curve diagram of the first cycle of Embodiment 1 of the present invention. Detailed Implementation

[0031] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0032] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0033] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0034] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0035] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0036] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0037] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0038] The present invention will now be described in further detail with reference to the accompanying drawings: This invention provides a gel polymer electrolyte membrane for an energy storage system, wherein the polymer has the following structural formula: .

[0039] This invention also provides a gel polymer electrolyte membrane for an energy storage system, its preparation method, and its application, specifically including the following steps: Step 1: Preparation of lithium 2-acrylamido-2-methylpropanesulfonate (AMPSLi): Dissolve 2-acrylamido-2-methylpropanesulfonic acid (AMPS) in deionized water, slowly add an equimolar amount of lithium carbonate, and stir the reaction at 55-65℃ for 3-5 h. After the reaction is complete, evaporate the solution to dryness to obtain a white solid AMPSLi, which is then dried in a vacuum drying oven at 75-85℃ for 10-14 h for later use.

[0040] Step 2: Preparation of prepolymer solution: Weigh AMPSLi, glycidyl methacrylate (GMA), and polyethylene glycol monomethyl ether acrylate (PEGA) in a mass ratio of 2.5~3.5:1.5~2.5:1.5~2.5. Add 1.0%~1.5% of the total mass of AMPSLi, GMA, and PEGA as a crosslinking agent (N,N-methylenebisacrylamide (MBA)). Then add 30%~40% of the total mass of AMPSLi, GMA, and PEGA as a plasticizer. Add 2.0~3.0 times the total mass of AMPSLi, GMA, and PEGA as deionized water and stir until completely dissolved to obtain a homogeneous prepolymer solution.

[0041] Step 3: Initiator addition and polymerization reaction Weigh out 1.0% to 1.5% of the initiator ammonium persulfate (APS) by mass of the prepolymer solution, add it to the prepolymer solution prepared in step two, stir evenly, pour it into a mold, and react in a constant temperature water bath at 60 to 70°C for 4 to 6 hours to form a gel-like polymer electrolyte.

[0042] Step 4: Post-processing: The gel polymer electrolyte is removed from the mold and dried in a vacuum drying oven at 60~70℃ for 18~22h to obtain a gel polymer electrolyte membrane for lithium batteries.

[0043] Preferably, the plasticizer is a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC), and the mass ratio of EC:DMC:EMC is 0.8~1.2:0.8~1.2:0.8~1.2.

[0044] The present invention also provides a lithium battery made of the above-mentioned gel polymer electrolyte membrane, wherein the initial discharge specific capacity of the battery measured at a 0.5C rate is 157 mAh·g. -1 .

[0045] The technical solution of the present invention will be further described in detail below through specific embodiments: Example 1: Preparation of AMPSLi: Weigh 10g AMPS and dissolve it in 50mL deionized water. Slowly add 5.3g lithium carbonate (equimolar with AMPS) and stir the mixture at 60℃ for 4 h. After the reaction is complete, evaporate the solution to dryness using a rotary evaporator to obtain white solid AMPSLi, which is then dried in a vacuum drying oven at 80℃ for 12 h for later use.

[0046] Preparation of prepolymer solution: Weigh AMPSLi, GMA, and PEGA in a mass ratio of 3:2:2, 6g, 4g, and 4g respectively. Add 1.2% of the total mass of MBA (i.e., 0.168g), and 35% of the total mass of plasticizer (EC:DMC:EMC=1:1:1, with a total mass of (6+4+4+0.168)÷(1-35%)×35%≈8.22g, of which EC, DMC, and EMC are each 2.74g). Add 30mL of deionized water and stir until completely dissolved to obtain a homogeneous prepolymer solution.

[0047] Polymerization reaction: Pour the prepolymer liquid into a glass mold, add 1.2% APS by mass of the prepolymer liquid (total mass of prepolymer liquid is 16+4+4+0.168+8.22+30≈52.388g, so the amount of APS added is 0.629g), stir evenly, and then place the mold in a 65℃ constant temperature water bath to react for 5 h to form a gel-like polymer electrolyte.

[0048] Post-processing: The gel polymer electrolyte is removed from the mold and dried in a vacuum drying oven at 65°C for 20 h to obtain a gel polymer electrolyte membrane for lithium batteries.

[0049] The electrolyte membrane prepared in this embodiment has an ionic conductivity of 1.2 × 10⁻⁶ at room temperature. -3 S / cm.

[0050] After being assembled into a CR2032 coin cell (positive electrode LiFePO4, negative electrode lithium metal), the discharge capacity is 157 mAh / g at 0.5C rate, 128 mAh / g at 2C rate, and 119 mAh / g at 5C rate.

[0051] Example 2: The difference between Example 2 and Example 1 is that the mass ratio of AMPSLi, GMA and PEGA is 2.5:2.5:2.5, while the proportions of other raw materials and reaction conditions are the same as in Example 1.

[0052] Example 3: The difference between Example 3 and Example 1 is that the amount of plasticizer added is 30% of the total mass of the AMPSLi, GMA and PEGA system, the mass ratio of EC:DMC:EMC is 0.8:1.2:1.0, and the proportions of other raw materials and reaction conditions are the same as in Example 1.

[0053] Example 4: The difference between Example 4 and Example 1 is that the polymerization reaction temperature is 60°C and the reaction time is 6 hours, while the proportions of other raw materials and reaction conditions are the same as in Example 1.

[0054] Example 5: The difference between Example 5 and Example 1 is that the amount of MBA added is 1.0% of the total mass of the AMPSLi, GMA and PEGA system, and the amount of APS added is 1.5% of the mass of the prepolymer liquid. The proportions of other raw materials and reaction conditions are the same as in Example 1.

[0055] Example 6: The difference between Example 6 and Example 1 is that the reaction temperature for AMPSLi preparation is 55°C and the reaction time is 5h; the post-treatment drying temperature is 60°C and the drying time is 22h, while the proportions of other raw materials and reaction conditions are the same as in Example 1.

[0056] Comparative Example 1 The specific steps for preparing the polymer electrolyte membrane in Comparative Example 1 are as follows: 1.00 g of polyvinylidene difluoride (PVDF) and 0.30 g of LiTFSI were dissolved in 30 ml of N-methylpyrrolidone (NMP) solution. The resulting solution was poured onto the surface of a glass mold and dried in a vacuum environment at 60 °C for 12 h to obtain a polymer electrolyte membrane, denoted as PVDF.

[0057] A LiFePO4 / PVDF / Li battery was assembled using PVDF and its charge-discharge cycle performance was tested at 60℃. The conductivity of the polymer electrolyte membrane at room temperature was measured to be 5.36 × 10⁻⁶. 5 S / cm -1 The initial discharge specific capacity of the battery was measured to be 136 mAh·g at a 0.5C rate. -1 .

[0058] Comparing Example 1 of the present invention with Comparative Example 1, it can be seen that the gel polymer electrolyte membrane prepared by using AMPSLi, GMA, and PEGA as composite monomers, adding MBA crosslinking agent and EC:DMC:EMC mixed plasticizer, and polymerizing in aqueous solution followed by vacuum drying, exhibits significantly better overall performance than the traditional PVDF-based polymer electrolyte membrane. Example 1: Ionic conductivity at room temperature (1.2 × 10⁻⁶) -3 S / cm) Comparison Example 1 (5.36×10 -5 The S / cm ratio is increased by approximately 22 times, and under the same positive electrode (LiFePO4), negative electrode (lithium metal) system and 0.5C rate, the initial discharge specific capacity (157 mAh / g) is higher than that of the PVDF-based electrolyte membrane (136 mAh / g). At the same time, it also exhibits good high-rate discharge capability (discharge capacity reaches 128 mAh / g and 119 mAh / g at 2C and 5C rates, respectively). This indicates that the synergistic effect of the composite monomer system, the introduction of plasticizer and the reasonable preparation process of the present invention can effectively improve the ion transport efficiency and interfacial compatibility of polymer electrolyte, thereby improving the energy output and rate performance of lithium battery.

[0059] like Figure 1 The image shows the electrochemical impedance spectroscopy (EIS) spectra of the gel polymer electrolyte membranes of Examples 1, 4, and Comparative Example 1 after 100 cycles. Figure 1 As can be seen, the high-frequency interfacial charge transfer impedance semicircle and the low-frequency ion diffusion oblique line are composed of a three-dimensional stable network structure rich in lithium active sites and continuous ion transport channels, thanks to the ternary copolymer system of AMPSLi lithium salt monomer, GMA epoxy crosslinking and PEGA ether oxygen coordination adopted in this invention. The diameter of the high-frequency semicircle in Examples 1 and 4 is much smaller than that in Comparative Example 1, and the interfacial charge transfer impedance is significantly reduced. At the same time, the impedance does not increase significantly after 100 cycles, indicating that the crosslinked network is structurally stable, does not collapse or degrade during long-term charge and discharge, and can continuously ensure the rapid migration of lithium ions. The curves of Examples 1 and 4 are highly overlapping, further proving that the process parameters of this invention are reasonable and the product performance is stable and controllable. From the perspective of interfacial impedance mechanism, it is confirmed that the electrolyte membrane of this invention can effectively reduce battery polarization and improve interfacial compatibility and cycle stability.

[0060] like Figure 2 The figure shown is a comparison chart of the discharge capacity of the optimal embodiment 1 and comparative example 1 at different discharge rates. Figure 2 As can be seen, in Example 1 of this invention, AMPSLi provides a sufficient lithium source and ion sites, GMA enhances mechanical support, PEGA efficiently coordinates and dissociates lithium ions through ether-oxygen bonds, and EC / DMC / EMC composite plasticizer optimizes the swelling and ion conduction environment, resulting in an electrolyte membrane with a room temperature ionic conductivity as high as 1.2 × 10⁻⁶. -3The discharge capacity (S / cm) at 0.5C, 2C, and 5C rates is significantly higher than that of the traditional PVDF base compared to Example 1, and the capacity decays gradually with increasing rate, maintaining 119 mAh even at a high rate of 5C. g -1 In contrast, Comparative Example 1 suffers from low ionic conductivity and poor interfacial compatibility, resulting in a rapid capacity drop at high rates. The rate response mechanism of this invention proves that the electrolyte membrane can achieve rapid charging and discharging, balancing mechanical strength and ion conduction performance, and solving the problems of poor rate performance and severe polarization at high rates of traditional electrolytes.

[0061] like Figure 3 The figure shows the first charge-discharge curve of Embodiment 1 of the present invention, which exhibits the best performance, at a rate of 0.5C. Figure 3 As can be seen, Embodiment 1 of the present invention relies on a single-ion conductive gel structure formed by the ternary copolymerization of AMPSLi-GMA-PEGA. This electrolyte membrane has close contact with the LiFePO4 positive electrode and the lithium metal negative electrode interface, with few side reactions. Its charge and discharge plateau spacing is narrow, the polarization voltage is low, the discharge voltage plateau is stable and has a long duration, and the initial discharge specific capacity reaches 157 mAh. g -1 The curves showed no obvious fluctuations, impurities, or abnormal voltage drops. The electrode-electrolyte interface mechanism and lithium-ion insertion / extraction mechanism fully demonstrate that the electrolyte membrane of Example 1 of this invention has high ion conduction efficiency and excellent chemical and electrochemical stability. It can fully utilize the capacity of electrode materials, improve battery energy density and charge / discharge efficiency, and exhibit comprehensive electrochemical performance far exceeding that of traditional electrolytes, thus meeting the practical application requirements of high-performance lithium batteries.

[0062] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A gel polymer electrolyte membrane in an energy storage system, characterized in that, The structural formula of the polymer is: 。 2. The gel polymer electrolyte membrane in the energy storage system according to claim 1, characterized in that, The room temperature ionic conductivity reaches 1.2 × 10⁻⁶. -3 S / cm.

3. A method for preparing a gel polymer electrolyte membrane in an energy storage system according to any one of claims 1 to 2, characterized in that, include: Lithium carbonate was added to a solution of 2-acrylamido-2-methylpropanesulfonic acid. After the reaction was completed, the solution was evaporated to obtain lithium 2-acrylamido-2-methylpropanesulfonate. Lithium 2-acrylamido-2-methylpropanesulfonate, glycidyl methacrylate and polyethylene glycol monomethyl ether acrylate are mixed, and crosslinking agent, plasticizer and deionized water are added. The mixture is stirred until completely dissolved to obtain a prepolymer solution. An initiator is added to the prepolymer solution, stirred evenly, and then poured into a mold. The mixture is then reacted in a constant temperature water bath to form a gel-like polymer electrolyte. The gel polymer electrolyte is removed from the mold and dried to obtain a gel polymer electrolyte membrane.

4. The method for preparing the gel polymer electrolyte membrane in the energy storage system according to claim 3, characterized in that, The molar ratio of 2-acrylamido-2-methylpropanesulfonic acid solution to lithium carbonate is 1:

1.

5. The method for preparing the gel polymer electrolyte membrane in the energy storage system according to claim 3, characterized in that, The reaction temperature of 2-acrylamido-2-methylpropanesulfonic acid solution with lithium carbonate is 55~65℃, and the reaction time is 3~5 h; The drying temperature of lithium 2-acrylamido-2-methylpropanesulfonate is 75~85℃, and the drying time is 10~14 h.

6. The method for preparing the gel polymer electrolyte membrane in the energy storage system according to claim 3, characterized in that, The mass ratio of lithium 2-acrylamido-2-methylpropanesulfonate, glycidyl methacrylate, and polyethylene glycol monomethyl ether acrylate is (2.5~3.5):(1.5~2.5):(1.5~2.5).

7. The method for preparing the gel polymer electrolyte membrane in the energy storage system according to claim 3, characterized in that, The crosslinking agent accounts for 1.0% to 1.5% of the total mass of lithium 2-acrylamido-2-methylpropanesulfonate, glycidyl methacrylate, and polyethylene glycol monomethyl ether acrylate. The crosslinking agent is N,N-methylenebisacrylamide; The plasticizer accounts for 30% to 40% of the total mass of lithium 2-acrylamido-2-methylpropanesulfonate, glycidyl methacrylate, and polyethylene glycol monomethyl ether acrylate. The plasticizer is a mixture of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate, with a mass ratio of (0.8~1.2):(0.8~1.2):(0.8~1.2). The mass of deionized water is 2.0 to 3.0 times the total mass of lithium 2-acrylamido-2-methylpropanesulfonate, glycidyl methacrylate, and polyethylene glycol monomethyl ether acrylate. The mass of the initiator is 1.0% to 1.5% of the mass of the prepolymer solution; The initiator is ammonium persulfate.

8. The method for preparing the gel polymer electrolyte membrane in the energy storage system according to claim 3, characterized in that, The constant temperature water bath temperature is 60~70℃, and the reaction time is 4-6 h.

9. The method for preparing the gel polymer electrolyte membrane in the energy storage system according to claim 3, characterized in that, The drying temperature of the gel polymer electrolyte is 60~70℃, and the drying time is 18~22 h.

10. A lithium battery, characterized in that, Made from the gel polymer electrolyte membrane according to any one of claims 1 to 2, characterized in that the initial discharge specific capacity at a 0.5C rate is 157 mAh·g. -1 .

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