A modified gel film, its preparation method and use

Abstract

The application belongs to the technical field of energy storage batteries, and provides a modified gel film, a preparation method and application thereof. The polyurethane acrylate is modified by trifluoromethylsulfonylimidazole and then cross-linked by using a photoinitiator, and a gel film with good mechanical properties is obtained through drying. The gel film utilizes the synergistic effect between the polymer and the modifier to construct a good network structure, can absorb different electrolytes and has a strong water retention rate, can effectively inhibit dendrite growth, and has good battery performance when applied to lithium batteries and zinc batteries, and further realizes high-temperature testing and soft package production. The application overcomes the problems of liquid electrolyte leakage and rapid dendrite growth, solves the problems of low conductivity, single directionality, high-temperature testing and soft package testing of the gel film, and has simple preparation process and low cost.

Description

Technical Field

[0001] This invention belongs to the field of chemical energy storage battery technology, specifically relating to a modified gel membrane, its preparation method, and its application. Background Technology

[0002] In the global acceleration of the green energy transition, the importance of chemical energy storage battery technology is self-evident; it is a key link in achieving efficient storage and flexible allocation of renewable energy. Lithium-ion batteries occupy an important position in consumer electronics and electric vehicles due to their high energy density, while aqueous zinc-ion batteries have great potential for large-scale energy storage due to their low cost, high safety, and abundant resources. As the core medium for ion transport within the battery, the electrolyte's performance directly determines the overall performance of the battery; therefore, the electrolyte has always been a key focus of battery technology research and development.

[0003] Traditional electrolyte-assembled batteries use liquid electrolytes, which pose a risk of leakage and have poor thermal stability. They are highly susceptible to safety accidents due to impact and high temperatures, and also exhibit numerous side reactions with the electrodes, resulting in a short cycle life. Furthermore, their poor compatibility with high-capacity materials significantly limits the improvement of energy density. In contrast, gels, with their solid-like form, have a low risk of leakage, excellent thermal stability, and can reduce safety hazards caused by leakage and high temperatures. Moreover, gels are highly adaptable in shape, can conform to the electrodes to ensure uniform ion transport, and have excellent vibration and impact resistance, possessing superior mechanical properties. Simultaneously, the three-dimensional network structure of gels provides stable ion transport channels, reducing ion aggregation and uneven diffusion, and ensuring continuous and stable ion transport.

[0004] However, the use of polymers in gel preparation has also revealed many problems. Polyethylene oxide (PEO) has high crystallinity at room temperature, which restricts ion migration and results in poor high-rate charge-discharge performance at room temperature; polyvinyl alcohol (PVA) has insufficient water resistance and electrochemical stability when used in aqueous batteries, and is prone to hydrolysis leading to performance degradation; the conductivity of polyurethane acrylate (PUA) itself also needs further optimization. Furthermore, current practical applications require further research into its safety under high-temperature conditions and its applicability for large-scale manufacturing. However, for many gels, the challenges of high-temperature testing and the difficulties in soft-pack fabrication still present numerous limitations and challenges.

[0005] Furthermore, it is worth noting that current gel preparation methods exhibit a significant single-target characteristic, often focusing solely on the adaptation needs of a specific type of battery. They lack universal, multi-functional application planning, making it difficult to flexibly switch between and utilize various battery systems. This results in significant shortcomings in cross-battery type versatility and multi-functional integration. Therefore, it is essential to develop a novel modified gel film that is leak-proof, highly safe, long-term stable, operates at high temperatures, is suitable for pouch applications, and meets the needs of different battery types. Summary of the Invention

[0006] To address the existing problems in the technology, such as leakage of liquid electrolytes, rapid dendrite growth, low safety and low energy density, difficulties in high-temperature testing and soft packaging of gel electrolytes, as well as the performance limitations and unidirectionality of gel membranes, this invention provides a modified gel membrane, its preparation method and application.

[0007] To achieve the above-mentioned objectives, this invention employs a modified gel membrane for energy storage batteries and its preparation method. Polyurethane acrylate is a polymer, which is modified by trifluoromethanesulfonyl imidazole and then a photoinitiator is used to promote internal polymerization and crosslinking to obtain a gel. The gel is dried to obtain the target gel membrane. The gel is then immersed in different electrolytes, and after swelling and saturation, it can be used in different energy storage batteries.

[0008] A modified gel membrane, the preparation method of which mainly includes the following steps:

[0009] S1. Polyurethane acrylate is dissolved in an organic reagent, and then a photoinitiator and trifluoromethylsulfonyl imidazole are added and stirred until complete to obtain a gel prepolymer solution.

[0010] S2. Transfer the gel prepolymer solution from S1 into a mold and irradiate it with a UV lamp to obtain a gel containing solvent.

[0011] S3. Transfer the mold from S2 to an oven to dry and remove the solvent, and obtain a gel film;

[0012] S4. Before use, immerse the gel membrane from S3 into the corresponding electrolyte. After swelling and saturation, obtain the final gel electrolyte and assemble the button cell.

[0013] Based on the above technical solutions, vanadium-based and lithium iron phosphate are used to provide the cycle stability of positive electrode materials for zinc-ion batteries and lithium-ion batteries, respectively. Since the gel is cross-linked and solidified under light, a large amount of electrolyte is retained in the gel system after adsorbing the electrolyte, and it has a good water retention rate, so the ionic conductivity is high.

[0014] Furthermore, in step S1, the mass fraction of the polyurethane acrylate dissolved in the organic solvent is 10–600 mg / mL.

[0015] Furthermore, in step S1, the organic solvent in which the polyurethane acrylate is dissolved includes one or more of anhydrous ethanol, anhydrous acetonitrile, N,N-methyleneformamide acetone, and ethyl acetate.

[0016] Furthermore, in step S1, the photoinitiator includes one or more of 2,4,6-(trimethylbenzoyl)diphenylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin dimethyl ether, and ethyl acetate.

[0017] Furthermore, in step S1, the mass fraction of the photoinitiator in the gel prepolymer solution is 1–20 mg / mL.

[0018] Furthermore, in step S1, the mass fraction of the trifluoromethylsulfonyl imidazole in the gel prepolymer solution is 1–60 mg / mL.

[0019] Furthermore, in step S1, the ambient temperature during the stirring process is 20–40°C, and the humidity is 30–75% RH.

[0020] Furthermore, in step S2, the amount of the gel prepolymer transferred into the mold is controlled to be between 50 and 500 μL.

[0021] Furthermore, in step S2, the wavelength of the ultraviolet lamp irradiation is controlled between 254 and 365 nm, preferably 254, 302, and 365 nm.

[0022] Furthermore, in step S2, the photoperiod for obtaining the gel after irradiation with ultraviolet light is 5 to 60 minutes.

[0023] Furthermore, in step S3, the drying temperature for transferring the gel membrane to an oven to remove the solvent is 60–90°C.

[0024] Furthermore, in step S3, the gel membrane is dried in a vacuum drying and blower drying environment.

[0025] Furthermore, in step S4, the immersion time of the gel membrane in the corresponding electrolyte is 2 to 24 hours.

[0026] Furthermore, in step S4, the zinc salt is selected from one or more of zinc sulfate, zinc methanesulfonate, zinc trifluoromethanesulfonate, zinc bis(trifluoromethanesulfonate)imide, zinc chloride hexafluorosilicate, zinc perchlorate, and zinc nitrate.

[0027] Furthermore, in step S4, the lithium salt is selected from one or more of lithium tetrafluoroborate, lithium hexafluorophosphate, lithium perchlorate, lithium bisfluorosulfonylimide, and lithium trifluoromethanesulfonate.

[0028] Furthermore, in step S4, the vanadium base is selected from one or more of vanadium pentoxide, vanadium dioxide, sodium vanadium octoxide hydrate, or vanadium hexadecyl oxide.

[0029] Furthermore, in step S4, the zinc salt concentration of the aqueous zinc electrolyte is 0.5–3 mol / L, and the lithium salt concentration of the lithium-ion electrolyte is 0.1–2 mol / L.

[0030] Furthermore, in step S4, the thickness of the zinc sheet in the assembled battery is 10-100 μm, and the thickness of the lithium-ion sheet is 250-600 mm.

[0031] Furthermore, the separator in the battery assembly in step S4 includes a glass fiber separator, a cellulose separator, or a hydrophilic polypropylene separator.

[0032] Based on the above technical solution, since polyurethane acrylate forms a network structure gel film under light, it has a good synergistic effect with trifluoromethanesulfonyl imidazole. The prepared gel film has high mechanical strength, not only with good mechanical properties and water retention, but also effectively inhibits the growth of zinc dendrites, which is beneficial to improving the rate performance and long-term stability of the battery, and is suitable for preparing energy storage batteries.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] 1. The gel membrane proposed in this invention has a simple preparation process, readily available raw materials, and low cost;

[0035] 2. The gel film containing trifluoromethanesulfonyl imidazole additive provided by the present invention can grow an organic-inorganic composite solid electrolyte interface protective layer in situ on the surface of the metal negative electrode based on chemical bonding, which inhibits dendrite growth and helps to extend the cycle life of the battery.

[0036] 3. The gel membrane proposed in this invention has good mechanical properties, and after swelling and saturation, it can greatly delay the volatilization of the internal electrolyte / electrolyte, and has a strong "water-locking" effect.

[0037] 4. The ionic conductivity of the gel modified according to the present invention has been significantly improved.

[0038] 5. The battery assembled with the gel electrolyte proposed in this invention can effectively inhibit the growth of zinc dendrites.

[0039] 6. The gel membrane proposed in this invention has multifunctionality and can be applied in multiple fields (such as aqueous zinc-ion batteries and lithium-ion batteries), and has stronger versatility and practicality. Attached Figure Description

[0040] Figure 1 Optical photographs of the deformation of the modified gel film provided for the invention.

[0041] Figure 2 The invention provides tensile test deformation data of the gel film before and after modification.

[0042] Figure 3 The invention provides compression test deformation data of the gel membrane before and after modification.

[0043] Figure 4 A bar chart comparing the tensile stress data of the gel film before and after modification, provided for the invention.

[0044] Figure 5 A bar chart comparing the compressive stress data of the gel film before and after modification, provided for the invention.

[0045] Figure 6 Optical photographs of the modified gel membrane before and after immersion in electrolyte, provided for the invention.

[0046] Figure 7 The water retention rate of the modified gel membrane provided by the invention was tested after being stored for 15 days at 25℃±3℃ and 40RH%±5RH%.

[0047] Figure 8 Electrochemical impedance test data of the gel membrane before and after modification were provided for the invention.

[0048] Figure 9 The invention provides test data on the ionic conductivity of the gel membrane before and after modification.

[0049] Figure 10 The invention provides test data for symmetrical cells of aqueous zinc-ion batteries assembled with modified gel electrolyte and liquid electrolyte.

[0050] Figure 11 The invention provides full-cell test data for the assembly of an aqueous zinc-ion battery with a modified gel electrolyte.

[0051] Figure 12 The invention provides full-cell test data for lithium-ion batteries assembled with modified gel electrolyte.

[0052] Figure 13 The invention provides scanning electron microscopy (SEM) of the negative electrode of the modified gel film and the liquid electrolyte assembled battery after cycling, to compare the effect of inhibiting dendrite growth.

[0053] Figure 14 The invention provides high-temperature full-cell test data for assembling aqueous zinc-ion batteries with modified gel electrolytes and liquid electrolytes.

[0054] Figure 15 The invention provides soft-pack test data for the modified gel electrolyte. Detailed Implementation

[0055] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but this should not be construed as limiting the scope of the present invention.

[0056] This invention addresses the aforementioned problems faced by energy storage batteries by designing a gel film composed of polyurethane acrylate as a polymer and trifluoromethanesulfonyl imidazole as a modifier. Polyurethane acrylate itself possesses excellent mechanical properties and adhesion, enabling it to form a stable network structure that effectively immobilizes trifluoromethanesulfonyl imidazole and the electrolyte containing metal salts, preventing the aggregation and shedding of active materials. During charge and discharge, the electrode materials undergo volume changes, and this stable network structure buffers the stress caused by these volume changes, maintaining the integrity and stability of the electrodes, reducing pulverization and loss of electrode materials, thereby improving the cycle stability of the battery. Furthermore, trifluoromethanesulfonyl imidazole has good ionic conductivity; after forming a gel film with polyurethane acrylate, it provides a more convenient channel for ion transport after immersion in the electrolyte, accelerating ion migration and thus improving the battery's charge and discharge efficiency and capacity performance.

[0057] There is a certain interaction between trifluoromethanesulfonyl imidazole and polyurethane acrylate. This interaction can regulate the properties of the electrolyte, improving its compatibility with electrode materials, facilitating the formation of a stable electrode / electrolyte interface, reducing interfacial resistance, minimizing polarization, solving the problem of dendrite growth at the negative electrode interface, and improving the battery's charge / discharge efficiency and capacity retention. This is beneficial for subsequent high-temperature testing and soft-pack fabrication applications. Simultaneously, the corresponding zinc / lithium salts can dissociate more effectively in the gel, further increasing ion concentration and improving ionic conductivity. This allows for faster ion insertion and extraction during charge and discharge, thereby enhancing the overall battery performance. The preparation method of this gel film is characterized by its simple process, mild preparation conditions, and low raw material cost, making it suitable for large-scale production.

[0058] This invention provides a modified gel film for energy storage batteries, its preparation method, and its applications in multiple fields. It includes an additive containing trifluoromethanesulfonyl imidazole, a polymer of polyurethane acrylate, a zinc sheet as the negative electrode material for aqueous zinc-ion batteries, and a lithium sheet as the negative electrode material for lithium-ion batteries.

[0059] Example 1

[0060] Under conditions of 20℃ and 30% RH, 0.01 g of polyurethane acrylate was completely dissolved in 1 mL of anhydrous ethanol. Then, 1 mg of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide and 7 mg of trifluoromethanesulfonyl imidazole were added and dissolved evenly, and set aside. The mixture was then irradiated with UV light at a wavelength of 265 nm for 5 min to obtain a cross-linked gel. The cross-linked gel was transferred to a vacuum oven and dried overnight at 60℃ to obtain a solidified membrane. Two solidified membranes were immersed in prepared 0.5 M zinc sulfate solution and 0.1 M lithium tetrafluoroborate solution, respectively, for 2 h to obtain the final gel electrolyte. These were then used for the assembly and testing of button cells and pouch cells using aqueous zinc-ion batteries and lithium-ion batteries.

[0061] Example 2

[0062] Under conditions of 25℃ and 40% RH, 50 mg of polyurethane acrylate was completely dissolved in 1 mL of N,N-methyleneformamide. Then, 5 mg of 1-hydroxy-cyclohexyl-phenyl ketone and 14 mg of trifluoromethanesulfonyl imidazole were added and dissolved thoroughly. The solution was then irradiated with a UV lamp at 302 nm for 10 min to obtain a cross-linked gel. The cross-linked gel was transferred to a forced-air oven and dried overnight at 60℃ to obtain a solidified membrane. Two solidified membranes were immersed in a prepared 1 M zinc methanesulfonate solution and a 0.2 M lithium hexafluorophosphate solution, respectively, for 4 h to obtain the final gel electrolyte. These were then used to assemble and test coin cells and pouch cells of aqueous zinc-ion and lithium-ion batteries.

[0063] Example 3

[0064] 100 mg of polyurethane acrylate was completely dissolved in 1 mL of anhydrous acetonitrile at 30 °C and 50% RH. Then, 10 mg of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 22 mg of trifluoromethanesulfonyl imidazole were added and dissolved thoroughly. The solution was then irradiated with a 365 nm UV lamp for 20 min to obtain a cross-linked gel. The cross-linked gel was transferred to a vacuum oven and dried overnight at 70 °C to obtain a solidified membrane. Two solidified membranes were immersed in a 1.5 M zinc trifluoromethanesulfonate solution and a 0.4 M lithium perfluoride solution, respectively, for 8 h to obtain the final gel electrolyte. This gel electrolyte was then used for the assembly and testing of coin cells and pouch cells using aqueous zinc-ion and lithium-ion batteries.

[0065] Example 4

[0066] 300 mg of polyurethane acrylate was completely dissolved in 1 mL of acetone at 35 °C and 60% RH. Then, 15 mg of benzoin dimethyl ether and 45 mg of trifluoromethylsulfonyl imidazole were added and dissolved thoroughly. The solution was then irradiated with UV light at 254 nm for 40 min to obtain a cross-linked gel. The cross-linked gel was transferred to a forced-air oven and dried overnight at 80 °C to obtain a solidified membrane. Two solidified membranes were immersed in a prepared 2 M zinc chloride solution and a 0.8 M lithium difluorosulfonyl imide solution, respectively, for 16 h to obtain the final gel electrolyte. These were then used for the assembly and testing of button cells and pouch cells in aqueous zinc-ion and lithium-ion batteries.

[0067] Example 5

[0068] 600 mg of polyurethane acrylate was completely dissolved in 1 mL of ethyl acetate at 40 °C and 75% RH. Then, 20 mg of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 60 mg of trifluoromethanesulfonyl imidazole were added and dissolved thoroughly. The solution was then irradiated with a 302 nm UV lamp for 60 min to obtain a cross-linked gel. The cross-linked gel was transferred to a vacuum oven and dried overnight at 90 °C to obtain a solidified membrane. Two solidified membranes were immersed in a prepared 3 M zinc nitrate solution and a 1 M lithium trifluoromethanesulfonate solution, respectively, for 24 h to obtain the final gel electrolyte. This gel electrolyte was then used for the assembly and testing of button cells and pouch cells using aqueous zinc-ion and lithium-ion batteries.

[0069] Comparative Example 1

[0070] 600 mg of polyurethane acrylate was completely dissolved in 1 mL of ethyl acetate at 40 °C and 75% RH. Then, 20 mg of 2-hydroxy-2-methyl-1-phenyl-1-propanone was added and dissolved thoroughly. The solution was then irradiated with a UV lamp at 302 nm for 60 min to obtain a cross-linked gel. The cross-linked gel was transferred to a vacuum oven and dried overnight at 90 °C to obtain a solidified membrane. Two solidified membranes were immersed in a prepared 3M zinc nitrate solution and a 1M lithium trifluoromethanesulfonate solution, respectively, for 24 h to obtain the final unmodified gel electrolyte. This gel electrolyte was then used for the assembly and testing of coin cells and pouch cells in aqueous zinc-ion and lithium-ion batteries.

[0071] Comparative Example 2

[0072] A CR2032 liquid coin cell was assembled using a 3M zinc nitrate solution and a 1M lithium trifluoromethanesulfonate solution for comparison.

[0073] Application and performance testing:

[0074] (1) Mechanical property testing of gel membrane:

[0075] The mechanical properties of the gel film provided by this invention were tested using a universal testing machine. Tensile properties parameters: dumbbell shape, length × width × height = 20.0 × 5.0 × 1.00 mm, 1 kN sensor, speed 10 mm / min. -1 Five parallel sets. Compression performance parameters: cylindrical shape, 20kN sensor, compression rate of 2mm·min. -1 Optical photographs and experimental data of its deformation are as follows: Figure 1 and Figures 2 to 5 As shown, this indicates that the gel membrane possesses good bending, tensile, and compressive strength, which are further improved after modification.

[0076] (2) Tests on the electrolyte adsorption effect and water retention rate of the gel membrane:

[0077] The gel membrane provided by this invention can adsorb both aqueous and organic electrolytes, indicating that it can adsorb a variety of electrolytes, thus possessing greater usability and applicable to various batteries. Furthermore, after wiping the electrolyte off the gel surface and placing it on paper, no significant electrolyte seepage occurred, indicating that the gel membrane has a certain "locking-in" effect on the electrolyte. Optical photographs taken before and after swelling saturation are shown below. Figure 6 As shown, the water retention rate test results for it after 15 days of storage at 25℃±3℃ and 40RH%±5RH% are as follows: Figure 7 As shown, the gel film still retains 85% of its mass after 15 days, indicating that it has an extremely high water retention rate, making it very easy to store and for long-term battery use.

[0078] (3) Conductivity test of gel membrane:

[0079] To further investigate the conductivity optimization effect of the gel membrane provided by this invention, button cell symmetric batteries were assembled using the gels before and after modification. The structure of the button cell is as follows: positive electrode shell, spacer, gel, spacer, spring, and negative electrode shell. The electrochemical impedance of the gel was tested, and the ionic conductivity formula was used as a reference. Ionic conductivity was measured. The electrochemical impedance and ionic conductivity results are as follows: Figure 8 and Figure 9 As shown, the optimization significantly improved the ionic conductivity, effectively solving the problem of poor conductivity in simple polyurethane acrylate gels and laying the foundation for good battery performance.

[0080] (4) Battery assembly and testing with gel membrane:

[0081] Assembly of button batteries: The structure of a complete button battery (aqueous zinc-ion battery) consists of: a positive electrode shell, a vanadium pentoxide electrode, an electrolyte, a glass fiber separator, a zinc plate, a gasket, a spring, and a negative electrode shell. The structure of a complete button battery (lithium-ion battery) consists of: a positive electrode shell, a lithium iron phosphate electrode, an electrolyte, a hydrophilic polypropylene separator, an electrolyte, a lithium plate, a gasket, a spring, and a negative electrode shell. For symmetrical batteries, simply replace the positive electrode with the corresponding zinc / lithium plate. For liquid batteries, replace the gel with "electrolyte, separator, electrolyte".

[0082] Assembly of pouch batteries: Required materials include aluminum-plastic film, negative electrode current collector, negative electrode, tabs, prepared positive electrode sheet, and gel. The process involves tab welding, stacking, molding, compaction, aging, and secondary molding. For liquid pouch batteries, simply replace the gel with electrolyte, separator, and electrolyte again. The positive electrode area of ​​the pouch battery should be controlled at 5*5cm.

[0083] Battery testing: The assembled button cells and pouch cells were charged and discharged on the Blue Battery Testing System, while the remaining electrochemical tests were conducted on the Shanghai Chenhua Electrochemical Workstation.

[0084] The results of its zinc-ion battery symmetric cell are as follows: Figure 10 As shown, it can be achieved at 1 mA·cm -2 Current density and 1 mAh·cm -2 The gel-assembled battery remained stable after 1700 hours of cycling at the deposition capacity. This indicates that the metal ion deposition / dissolution process is relatively uniform and stable, with fewer side reactions with the electrolyte, a stable electrochemical window, and favorable ion transport. Furthermore, the gel itself is not easily decomposed, ensuring interfacial stability and the long-lasting effectiveness of the SEI film, thus laying a solid foundation for its reliable application in numerous fields.

[0085] Meanwhile, the gel electrolytes formed by soaking the gel membrane provided by the present invention in zinc salt / lithium salt electrolytes were assembled into full cells of aqueous zinc-ion batteries and lithium-ion batteries, respectively, and tested. Figure 11 and Figure 12 The batteries maintain excellent capacity retention rates of 94.3% and 98.7% under prolonged conditions. This indicates a high degree of matching between the positive and negative electrode materials and the gel in terms of capacity, voltage plateau, and other aspects. It also demonstrates excellent ionic conductivity and a stable electrochemical window, effectively reducing resistance and polarization, and facilitating ion migration and maintaining the internal environment. Furthermore, the high capacity retention rates of both lithium-ion and zinc-ion batteries assembled with this gel further prove its applicability to various energy storage batteries, effectively avoiding the unidirectional nature of traditional gels and giving the gel membrane provided by this invention greater practicality and multifunctionality.

[0086] SEM images were taken of the negative electrode sheet after long cycling, and the results are as follows: Figure 13As shown. Figure 13 The battery assembled in liquid form showed significant dendrite growth on the zinc plate after cycling, while the battery assembled in gel form exhibited a flat negative electrode surface with no obvious byproduct formation. This indicates that the gel provided by this invention can suppress side reactions and effectively inhibit dendrite growth. This further improves battery safety, preventing dendrites from piercing the positive and negative electrode contacts and causing short circuits, thus reducing the risk of spontaneous combustion and explosion. Secondly, it can extend battery life, reduce irreversible capacity loss caused by dendrite breakage, and maintain charge and discharge performance. Furthermore, it helps improve battery performance, achieving uniform carrier deposition and rapid transport, and optimizing coulombic efficiency.

[0087] The button cell battery was subjected to a long-cycle test at 60°C, and the results were as follows: Figure 14 As shown, the battery assembled with the modified gel can operate normally at 60℃, and compared with unmodified gel and liquid batteries, the modified gel exhibits more stable cycle performance. High-temperature testing of batteries is of great significance. It is a key measure to ensure battery safety, minimizing the risk of thermal runaway, combustion, and explosion under extreme high-temperature conditions. The gel membrane provided in this study can operate at high temperatures, which helps expand the application fields of batteries. Through testing, batteries suitable for high-temperature scenarios such as special industrial applications, military equipment, and electronic devices in tropical regions can be screened, laying a solid foundation for their application in multiple fields.

[0088] Furthermore, the gel membrane provided by this invention was also successfully used to make a pouch battery, and its pouch appearance and performance data are as follows: Figure 15 As shown, its capacity retention rate reaches 82.43% after 100 cycles. The successful operation of the pouch battery further confirms the significant practicality of the gel proposed in this study. With a wider capacity range, flexible customizable shape, and higher energy density, it can further meet the diverse power needs of various devices, from mobile phones to electric vehicles, providing longer-lasting power and benefiting long-range devices. Simultaneously, the flexibility of its gel pouch further enhances battery portability, expanding the possibilities for practical battery applications.

Claims

1. A method for preparing a modified gel membrane, characterized in that, Includes the following steps: S1. Dissolve polyurethane acrylate in an organic solvent, then add photoinitiator and trifluoromethylsulfonyl imidazole and stir until complete to obtain gel prepolymer solution; The specific ingredients are as follows: The mass fraction of the polyurethane acrylate dissolved in the organic solvent is 10–600 mg / mL; The organic solvents in which the polyurethane acrylate is soluble include one or more of anhydrous ethanol, anhydrous acetonitrile, N,N-methyleneformamide acetone, and ethyl acetate. The photoinitiator includes one or more of 2,4,6-(trimethylbenzoyl)diphenylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin dimethyl ether, and ethyl acetate; The photoinitiator has a mass fraction of 1–20 mg / mL in the gel prepolymer solution; The mass fraction of the trifluoromethylsulfonyl imidazole in the gel prepolymer solution is 1–60 mg / mL; S2. Transfer the gel prepolymer solution from S1 into a mold and irradiate it with a UV lamp to obtain a gel containing organic solvent. S3. Transfer the mold from S2 to an oven to dry and remove the organic solvent, and obtain the modified gel film.

2. The method for preparing a modified gel membrane according to claim 1, characterized in that, In step S1, the ambient temperature during the stirring process is 20–40°C and the humidity is 30–75% RH.

3. The method for preparing a modified gel membrane according to claim 1, characterized in that, In step S2, the wavelength of the ultraviolet lamp irradiation is controlled at 254~365nm; the irradiation time for obtaining the gel after ultraviolet lamp irradiation is 5~60min.

4. The method for preparing a modified gel membrane according to claim 1, characterized in that, In step S3, the gel membrane is transferred to an oven to dry and remove the organic solvent at a drying temperature of 60–90°C.

5. A modified gel membrane, characterized in that, Obtained by the preparation method according to any one of claims 1 to 4.

6. The application of the modified gel membrane according to claim 5, characterized in that, Used to manufacture energy storage batteries.

7. The application of the modified gel membrane according to claim 6, characterized in that, The specific method is as follows: the modified gel membrane is immersed in the electrolyte, and after swelling and saturation, the final gel electrolyte is obtained and the battery is assembled.

8. The application of the modified gel membrane according to claim 7, characterized in that, The modified gel membrane is immersed in the corresponding electrolyte for 2 to 24 hours.

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