Modified gel film as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of energy storage batteries, and provides a modified gel film and a preparation method and application thereof.Urethane acrylate is modified through trifluoromethylsulfonyl imidazole and then crosslinked through a photoinitiator, and the gel film with good mechanical properties is obtained through drying. According to the gel film, a good network structure is constructed by utilizing the synergistic effect between the polymer and the modifier, different electrolytes can be absorbed, the water retention rate is high, meanwhile, dendritic crystal growth can be effectively inhibited, good battery performance is achieved when the gel film is applied to a lithium battery and a zinc battery, and high-temperature testing and soft package manufacturing are further achieved. The problems of liquid leakage and rapid dendritic crystal growth of the existing liquid electrolyte are solved, the problems of low conductivity, single directivity, high-temperature test, soft package test and the like of the gel film are solved, the whole preparation process is simple, and the cost is low.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical energy storage batteries, and in particular relates to a modified gel membrane and a preparation method and application thereof. Background Art

[0002] In the process of accelerating the global 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 deployment of renewable energy. Lithium-ion batteries occupy an important position in the field of consumer electronics and electric vehicles due to their high energy density, while aqueous zinc-ion batteries have great potential in large-scale energy storage due to their low cost, high safety and abundant resources. As the core medium for ion transmission within the battery, the performance of the electrolyte directly determines the overall performance of the battery. Therefore, electrolytes have always been the focus of battery technology research and development.

[0003] Batteries assembled with traditional electrolytes have liquid electrolytes, which have the risk of liquid leakage and poor thermal stability. They are easily prone to safety accidents due to impact and high temperature, and have many side reactions with electrodes, resulting in a short cycle life. They are not compatible with high specific capacity materials, which greatly limits the improvement of energy density. In contrast, gels are similar to solid forms, have a low risk of liquid leakage, and have good thermal stability, which can reduce safety hazards caused by leakage and high temperature. In addition, the gel shape is highly adaptable and can fit the electrode to ensure uniform ion transmission. It also has excellent vibration and impact resistance and higher mechanical properties. At the same time, the three-dimensional network structure of the gel can also provide a stable ion transmission channel, reduce ion aggregation and uneven diffusion, and ensure continuous and stable ion transmission.

[0004] However, many problems are exposed when polymers are used to prepare gels. Polyethylene oxide (PEO) has high room temperature crystallinity, limited ion migration, and poor high-rate charge and discharge performance at room temperature; when polyvinyl alcohol (PVA) is used in aqueous batteries, it has insufficient water resistance and electrochemical stability, and is easily hydrolyzed to cause performance degradation; the conductivity of polyurethane acrylate (PUA) itself also needs to be further optimized. In addition, the current social practical situation requires further research on its safety under high temperature conditions and its applicability for actual large-scale manufacturing. However, for many gels, the difficulties of high-temperature testing and the difficulties of soft-pack production still face many challenges and limitations.

[0005] It is also worth noting that many current gel preparation schemes show significant single-directional characteristics, often focusing only on the adaptation needs of a specific type of battery and developing design considerations. The lack of universal multifunctional application planning makes it difficult to flexibly switch and play a role in a variety of different types of battery systems, and there are obvious deficiencies in the versatility and multifunctional integration across battery types. For this reason, it is extremely necessary to prepare a new modified gel membrane that can prevent leakage, has high safety, long stability, high temperature operation, soft-pack application, and meet the needs of different types of batteries. Summary of the invention

[0006] In view of the problems of liquid electrolyte leakage, rapid dendrite growth, low safety and low energy density, high temperature testing of gel electrolyte and soft package production, as well as the performance limitations and single directionality of gel membranes in the prior art, the present invention provides a modified gel membrane and a preparation method and application thereof.

[0007] In order to achieve the above-mentioned purpose of the invention, the present scheme adopts a modified gel membrane for energy storage batteries and a preparation method thereof. Polyurethane acrylate is a polymer, which is modified with trifluoromethanesulfonyl imidazole and then a photoinitiator is used to promote internal polymerization and cross-linking to obtain a gel. The gel is dried to obtain a target gel membrane, and then the gel is immersed in different electrolytes. After swelling and saturation, it can be used in different energy storage batteries.

[0008] A modified gel membrane and a preparation method thereof mainly comprise the following steps:

[0009] S1, adding polyurethane acrylate to an organic reagent to dissolve it, then adding a photoinitiator and trifluoromethylsulfonyl imidazole to it and further stirring to obtain a gel prepolymer solution;

[0010] S2, transferring the gel prepolymer in S1 into a mold, and irradiating it with an ultraviolet lamp to obtain a gel containing a solvent;

[0011] S3, transferring the mold in S2 to an oven for drying to remove the solvent, thereby obtaining a gel film;

[0012] S4. Before use, immerse the gel film in S3 in the corresponding electrolyte, swell to saturation to obtain the final gel electrolyte and assemble the button battery.

[0013] Based on the above technical scheme, vanadium-based and lithium iron phosphate are used to provide the cycle stability of zinc-ion battery and lithium-ion battery positive electrode materials 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 good water retention rate, so the ion conductivity is high.

[0014] Furthermore, in step S1, the mass fraction of the polyurethane acrylate dissolved in the organic solvent is 10 to 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 to 20 mg / mL.

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

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

[0020] Furthermore, in step S2, the amount of the gel prepolymer solution transferred to the mold is controlled to be 50-500ul.

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

[0022] Furthermore, in step S2, the irradiation time of the gel obtained after irradiation with the ultraviolet lamp is 5 to 60 minutes.

[0023] Furthermore, in step S3, the gel film is transferred to an oven for drying to remove the solvent, and the drying temperature is 60-90°C.

[0024] Furthermore, in step S3, the drying environment of the gel film is vacuum drying and forced air drying.

[0025] Furthermore, in step S4, the gel film is immersed in the corresponding electrolyte for 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, zinc 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 bis(fluorosulfonyl)imide, and lithium trifluoromethanesulfonate.

[0028] Furthermore, in step S4, the vanadium base is selected from one or more of vanadium pentoxide, vanadium dioxide, hydrated sodium trivanadium octoxide or tridecavanadium hexaoxide.

[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 assembled battery zinc sheet is 10-100 μm, and the thickness of the lithium-ion lithium sheet is 250-600 mm.

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

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

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The gel film proposed by the present invention has a simple preparation process, readily available raw materials and low cost;

[0035] 2. The gel film containing trifluoromethylsulfonyl imidazole additive provided by the present invention can in situ grow an organic-inorganic composite solid electrolyte interface protection layer on the surface of the metal negative electrode based on chemical bonding to inhibit dendrite growth, which is beneficial to prolonging the cycle life of the battery.

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

[0037] 4. The ionic conductivity of the gel proposed in the present invention is significantly improved after modification.

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

[0039] 6. The gel membrane proposed in the present invention is multifunctional and can be applied in multiple fields (such as aqueous zinc ion batteries and lithium ion batteries), and has stronger versatility and practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The deformation optical photograph of the modified gel film provided by the invention.

[0041] Figure 2 The invention provides the 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 film before and after modification.

[0043] Figure 4 The bar graph comparison of the tensile stress data of the gel film before and after modification provided by the invention.

[0044] Figure 5 The bar graphs provide a comparison of the compressive stress data of the gel film before and after modification provided by the invention.

[0045] Figure 6 Optical photographs of the modified gel membrane provided by the invention before and after being immersed in electrolyte.

[0046] Figure 7 The water retention rate test of the modified gel film provided by the invention was carried out under the environment of 25°C±3°C and 40RH%±5RH% for 15 days.

[0047] Figure 8 The invention provides electrochemical impedance test data of the gel membrane before and after modification.

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

[0049] Fig.10 The invention provides symmetrical battery test data of aqueous zinc ion batteries assembled with modified gel electrolyte and liquid electrolyte.

[0050] Fig.11 The invention provides full-cell test data of aqueous zinc-ion batteries assembled with modified gel electrolyte.

[0051] Fig.12 The invention provides full battery test data of lithium-ion batteries assembled with modified gel electrolyte.

[0052] Fig.13 The invention provides a scanning electron microscope (SEM) of the negative electrode of the battery assembled with the gel film and liquid electrolyte before and after modification after cycling to compare the effect of inhibiting dendrite growth.

[0053] Fig.14 The invention provides high-temperature full-cell test data of aqueous zinc-ion batteries assembled with gel electrolyte and liquid electrolyte before and after modification.

[0054] Fig.15 The soft pack test data of the modified gel electrolyte provided by the invention. DETAILED DESCRIPTION

[0055] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the specific implementation modes of the present invention are described in detail below with reference to the accompanying drawings, but they should not be construed as limiting the applicable scope of the present invention.

[0056] In view of the above-mentioned problems faced by energy storage batteries, the present invention designs a gel film composed of polyurethane acrylate as a polymer and trifluoromethylsulfonyl imidazole as a modifier. Polyurethane acrylate itself has excellent mechanical properties and adhesion, and can form a stable network structure, effectively fix trifluoromethylsulfonyl imidazole and an electrolyte with a metal salt therein, and prevent the agglomeration and shedding of active substances. During the charge and discharge process, the electrode material will undergo volume changes, and this stable network structure can buffer the stress caused by this volume change, maintain the integrity and stability of the electrode, reduce the pulverization and loss of the electrode material, and thus improve the cycle stability of the battery. In addition, trifluoromethylsulfonyl imidazole has good ionic conductivity. After forming a gel film with polyurethane acrylate, after being soaked in an electrolyte, it can provide a more convenient channel for ion transmission, accelerate the migration speed of ions, and thus improve the charge and discharge efficiency and capacity performance of the battery.

[0057] There is a certain interaction between trifluoromethylsulfonyl imidazole and polyurethane acrylate, which can adjust the properties of the electrolyte, make it more compatible with the electrode material, help form a stable electrode / electrolyte interface, reduce interface resistance, reduce the occurrence of polarization, solve the problem of dendrite growth at the negative electrode interface, improve the battery's charge and discharge efficiency and capacity retention rate, and help subsequent high-temperature testing and soft-pack manufacturing applications. At the same time, the corresponding zinc salt / lithium salt can be better dissociated in the gel, further increasing the ion concentration, improving the ion conductivity, and enabling the battery to embed and extract ions more quickly during the charge and discharge process, thereby enhancing the overall performance of the battery. The preparation method of the gel film has the characteristics of simple preparation process, mild preparation conditions, low raw material cost, etc., and is convenient for large-scale production.

[0058] The invention provides a modified gel film for energy storage battery and a preparation method and multi-field applications thereof, comprising an additive containing trifluoromethylsulfonyl imidazole, a polymer of polyurethane acrylate, a zinc sheet as the negative electrode material of an aqueous zinc ion battery, and a lithium sheet as the negative electrode material of a lithium ion battery.

[0059] Example 1

[0060] At 20°C and 30RH%, 0.01g of polyurethane acrylate was completely dissolved in 1mL of anhydrous ethanol. Then 1mg (2,4,6-trimethylbenzoyl) diphenylphosphine oxide and 7mg trifluoromethylsulfonyl imidazole were added, dissolved evenly and set aside. Irradiate with a wavelength of 265nm of ultraviolet lamp for 5min to obtain a cross-linked gel. The cross-linked gel was transferred to a vacuum oven and dried overnight at 60°C to obtain a solidified film. The two solidified films were immersed in the prepared 0.5M zinc sulfate solution and 0.1M lithium tetrafluoroborate solution respectively, and the immersion time was 2h to obtain the final gel electrolyte. The button cells and soft-pack batteries of aqueous zinc ion batteries and lithium ion batteries were assembled and tested.

[0061] Example 2

[0062] At 25°C and 40RH%, 50mg of polyurethane acrylate was completely dissolved in 1mL of N,N-methyleneformamide. Then 5mg of 1-hydroxy-cyclohexyl-phenyl ketone and 14mg of trifluoromethylsulfonyl imidazole were added, and after uniform dissolution, they were set aside. Irradiate with a wavelength of 302nm of ultraviolet lamp for 10min to obtain a cross-linked gel. The cross-linked gel was transferred to a forced air oven and dried overnight at 60°C to obtain a solidified film. The two solidified films were immersed in the prepared 1M zinc methanesulfonate solution and 0.2M lithium hexafluorophosphate solution respectively, and the immersion time was 4h to obtain the final gel electrolyte. The button cells and soft-pack batteries of aqueous zinc ion batteries and lithium ion batteries were assembled and tested.

[0063] Example 3

[0064] At 30°C and 50RH%, 100mg of polyurethane acrylate was completely dissolved in 1mL of anhydrous acetonitrile. Then 10mg of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 22mg of trifluoromethylsulfonyl imidazole were added, dissolved evenly and set aside. Irradiate with a wavelength of 365nm of ultraviolet lamp for 20min 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 film. The two solidified films were immersed in the prepared 1.5M trifluoromethanesulfonate zinc solution and 0.4M lithium perfluoride solution respectively, and the immersion time was 8h to obtain the final gel electrolyte. The button cells and soft-pack batteries of aqueous zinc ion batteries and lithium ion batteries were assembled and tested.

[0065] Example 4

[0066] At 35°C and 60RH%, 300mg of polyurethane acrylate was completely dissolved in 1mL of acetone. Then 15mg of benzoin dimethyl ether and 45mg of trifluoromethylsulfonyl imidazole were added, dissolved evenly and set aside. Irradiate with a wavelength of 254nm of ultraviolet lamp for 40min to obtain a cross-linked gel. Transfer the cross-linked gel to a forced air oven and dry it overnight at 80°C to obtain a solidified film. The two solidified films were immersed in the prepared 2M zinc chloride solution and 0.8M lithium bis(fluorosulfonyl)imide, respectively, for an immersion time of 16h to obtain the final gel electrolyte. The button cells and soft-pack batteries of aqueous zinc-ion batteries and lithium-ion batteries were assembled and tested.

[0067] Example 5

[0068] At 40°C and 75RH%, 600mg of polyurethane acrylate was completely dissolved in 1mL of ethyl acetate. Then 20mg of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 60mg of trifluoromethylsulfonyl imidazole were added, and after uniform dissolution, they were set aside. Irradiate with a wavelength of 302nm of ultraviolet lamp for 60min 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 film. The two solidified films were immersed in the prepared 3M zinc nitrate solution and 1M lithium trifluoromethylsulfonate solution respectively, and the immersion time was 24h to obtain the final gel electrolyte. The button cells and soft-pack batteries of aqueous zinc ion batteries and lithium ion batteries were assembled and tested.

[0069] Comparative Example 1

[0070] At 40°C and 75RH%, 600mg of polyurethane acrylate was completely dissolved in 1mL of ethyl acetate. Then 20mg of 2-hydroxy-2-methyl-1-phenyl-1-propanone was added and dissolved evenly for standby use. Irradiate with a UV lamp at a wavelength of 302nm for 60min 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 film. The two solidified films were immersed in the prepared 3M zinc nitrate solution and 1M lithium trifluoromethanesulfonate solution respectively for 24h to obtain the final unmodified gel electrolyte. The button cells and soft-pack batteries of aqueous zinc ion batteries and lithium ion batteries were assembled and tested.

[0071] Comparative Example 2

[0072] 3M zinc nitrate solution and 1M lithium trifluoromethanesulfonate solution were prepared and assembled into a CR2032 liquid button battery for comparison.

[0073] Application and performance testing:

[0074] (1) Mechanical properties test of gel film:

[0075] The mechanical properties of the gel film provided by the present invention were tested using a universal material testing machine. Tensile performance parameters: dumbbell shape, length × width × height = 20.0 × 5.0 × 1.00 mm, 1KN sensor, rate of 10 mm min -1 , 5 sets in parallel. Compression performance parameters: cylindrical, 20KN sensor, compression rate 2mm·min -1 The optical photos and experimental data of its deformation are as follows: Figure 1 and Figures 2 to 5 As shown. It shows that the gel film has good bending, tensile and compressive strength, and the strength is further improved after modification.

[0076] (2) Gel membrane adsorption electrolyte effect and water retention rate test:

[0077] The gel membrane provided by the present invention can adsorb both aqueous electrolyte and organic electrolyte, indicating that the gel membrane can adsorb a variety of electrolytes, has stronger usability, and can be used in a variety of batteries. After wiping the electrolyte on the surface of the gel and placing it on paper, there is no obvious electrolyte leakage, indicating that the gel membrane has a certain "locking" effect on the electrolyte. Optical photos taken before and after swelling saturation are shown in Figure 1. Figure 6 The test results of water retention rate of the product stored at 25℃±3℃, 40RH%±5RH% for 15 days are shown in Figure 7 As shown, it still has 85% of its mass after 15 days, indicating that the gel film has extremely strong water retention and is very convenient for storage and long-term use of batteries.

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

[0079] In order to further explore the conductivity optimization effect of the gel film provided by the present invention, the gel before and after modification was assembled into a button symmetrical battery, and the structure of the button battery was: positive electrode shell, gasket, gel, gasket, spring and negative electrode shell. The electrochemical impedance of the gel was tested, and the ionic conductivity formula was used. The electrochemical impedance and ionic conductivity results are as follows: Figure 8 and Fig. 9 It shows that after optimization, the ionic conductivity has been greatly improved, which effectively solves the problem of poor conductivity of simple polyurethane acrylate gel and lays a good foundation for subsequent good battery performance.

[0080] (4) Gel film battery assembly and testing:

[0081] Assembly of button cells: The structure of a button cell assembled from an aqueous zinc-ion battery is: positive electrode shell, vanadium pentoxide pole piece, electrolyte, glass fiber diaphragm, electrolyte, zinc sheet, gasket, shrapnel and negative electrode shell. The structure of a button cell assembled from a lithium-ion battery is: positive electrode shell, lithium iron phosphate pole piece, electrolyte, hydrophilic polypropylene diaphragm, electrolyte, lithium sheet, gasket, shrapnel and negative electrode shell. For a symmetrical battery, just replace the positive pole piece with the corresponding zinc sheet / lithium sheet. For a liquid battery, just replace the gel with "electrolyte, diaphragm, electrolyte".

[0082] Assembly of soft pack battery: The required materials include aluminum plastic film, negative electrode current collector, negative electrode, tab, prepared positive electrode sheet and gel. The above materials are subjected to tab welding, lamination, plastic sealing, compaction, aging and secondary plastic sealing. For liquid soft pack battery, the gel is replaced with "electrolyte, diaphragm, electrolyte". The positive electrode area of ​​the soft pack is controlled at 5*5cm.

[0083] Battery testing: The assembled button cells and soft-pack batteries were subjected to charge and discharge tests on the Blue Power battery testing system, and the remaining electrochemical tests were conducted on the Shanghai Chenhua electrochemical workstation.

[0084] The symmetric battery results of the zinc ion battery are as follows Fig.10 As shown, it can be -2 The current density and 1 mAh cm -2 The deposition capacity of the gel is still stable after 1700h cycle. This shows that the metal ion deposition / dissolution process of the gel-assembled battery is relatively uniform and stable, with few side reactions with the electrolyte, a stable electrochemical window, which is conducive to ion transmission and is not easy to decompose itself, ensuring the stability of the interface and the long-term effectiveness of the SEI film, laying a solid foundation for its reliable application in many fields.

[0085] At the same time, the gel electrolyte formed by the gel membrane provided by the present invention after being immersed in zinc salt / lithium salt electrolyte respectively is assembled into full batteries of aqueous zinc ion batteries and lithium ion batteries, and the full batteries are tested. Fig.11 and Fig.12 The battery can still maintain an excellent capacity retention rate under long-term conditions, reaching 94.3% and 98.7% respectively. This shows that the positive and negative electrode materials and the gel are highly matched in terms of capacity, voltage platform and other aspects, with good ion conductivity and stable electrochemical window, effectively reducing resistance and polarization, and facilitating ion migration and maintaining the internal environment. The lithium-ion battery and zinc-ion battery assembled by the gel also have a high capacity retention rate, which further proves that the gel can be applied to a variety of energy storage batteries, effectively avoiding the single directionality of traditional gels, making the gel film provided by the present invention more practical and multifunctional.

[0086] The negative electrode sheet after long cycle was photographed by SEM, and the results are as follows Fig.13shown. Fig.13 The results show that the zinc sheet of the battery assembled by liquid shows obvious dendrite growth after cycling, while the surface of the negative electrode sheet of the battery assembled by gel is flat after cycling, and no obvious by-products are formed, indicating that the gel provided by the present invention can inhibit side reactions and effectively inhibit dendrite growth. This can further improve battery safety, prevent dendrites from piercing the contact between the positive and negative electrodes and causing short circuits, and reduce the risks 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 to improve battery performance, achieve uniform deposition and rapid transmission of carriers, and optimize coulomb efficiency.

[0087] The button battery was placed at 60°C for a long cycle test. The results are as follows Fig.14 As shown. The battery assembled with the modified gel can operate normally at 60°C, and compared with the unmodified gel and liquid batteries, the modified gel has a more stable cycle effect. Testing the battery at high temperature is of great significance. It is a key measure to ensure battery safety, and can avoid hidden dangers such as thermal runaway, combustion and explosion to the greatest extent under extreme high temperature conditions. The gel membrane provided in this study can operate at high temperatures, which helps to expand the application field of batteries. Through testing, batteries suitable for high temperature scenarios such as special industries, military equipment, and electronic equipment in tropical areas can be selected, laying a solid foundation for their application in multiple fields.

[0088] In addition, the gel film provided by the present invention is also successfully made into a soft pack battery, and its soft pack appearance and performance data are as follows: Fig.15 As shown in the figure, its capacity retention rate can reach 82.43% after 100 cycles. The successful operation of the soft-pack battery further confirms that the gel proposed in this study has significant practicality. It has a wider capacity range, flexible and customizable shape, and higher energy density. It can further meet the different power requirements of various devices from mobile phones to electric vehicles, provide more lasting power, and facilitate the use of long-lasting devices. At the same time, the flexibility of its gel soft pack can further improve the portability of the battery, expanding more possibilities for the practical application of the battery.

Claims

1. A method for preparing a modified gel membrane, characterized in that: The following steps are involved: S1, adding polyurethane acrylate to an organic reagent to dissolve it, then adding a photoinitiator and trifluoromethylsulfonyl imidazole and stirring thoroughly to obtain a gel prepolymer solution; S2, transferring the gel prepolymer in S1 into a mold, and irradiating it with an ultraviolet lamp to obtain a gel containing a solvent; S3. Transfer the mold in S2 to an oven for drying to remove the solvent, thereby obtaining a modified gel film.

2. The method for preparing a modified gel membrane according to claim 1, characterized in that: The raw materials in step S1 are specifically: The mass fraction of the polyurethane acrylate dissolved in the organic solvent is 10 to 600 mg / mL; 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; 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 mass fraction of the photoinitiator in the gel prepolymer solution is 1 to 20 mg / mL; The mass fraction of the trifluoromethylsulfonyl imidazole in the gel prepolymer solution is 1 to 60 mg / mL.

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

4. The method for preparing a modified gel membrane according to claim 1, characterized in that: In step S2, the amount of the gel prepolymer solution transferred to the mold is controlled to be 50-500ul.

5. The method for preparing a modified gel membrane according to claim 1, characterized in that: In step S2, the wavelength of the gelling UV lamp is controlled at 254-365 nm; the irradiation time of the gel obtained after the UV lamp irradiation is 5-60 minutes.

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

7. A modified gel membrane, characterized in that: Obtained according to the preparation method according to any one of claims 1 to 6.

8. The use of a modified gel membrane according to claim 7, characterized in that: Used to prepare energy storage batteries.

9. The use of a modified gel membrane according to claim 8, characterized in that: The specific method is: immersing the modified gel membrane in an electrolyte, swelling and saturating to obtain a final gel electrolyte and assembling a battery.

10. The use of a modified gel membrane according to claim 9, characterized in that: The modified gel membrane is immersed in the corresponding electrolyte for 2 to 24 hours.

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