A gel battery and its preparation method

Abstract

This invention discloses a gel battery and its preparation method, comprising the following steps: liquid injection, room temperature wetting, high-temperature polymerization, high-temperature formation, high-temperature aging, and room temperature capacity testing. Specifically: in the liquid injection step, the liquid base solution and gel components are injected simultaneously to prevent uneven distribution of the gel components within the battery, simplifying the operation and facilitating implementation; room temperature wetting ensures the gel electrolyte exists in a liquid state within the battery, facilitating the full diffusion of the gel components into the vicinity of the active material, improving the wetting effect of the gel electrolyte, and reducing the interfacial resistance between the polymerized electrolyte and the electrode; high-temperature polymerization causes the monomers and initiators in the liquid electrolyte distributed around the active material to react and polymerize, locking the liquid base solution to form a non-flowing gel electrolyte; placing the high-temperature polymerization step before high-temperature formation effectively avoids the influence of monomers and / or initiators on the formation of the SEI film during the formation process, establishing a stable interface with good performance.

Description

Technical Field

[0001] This invention belongs to the field of gel battery production technology, and relates to a gel battery and its preparation method, particularly to the impregnation, polymerization and formation methods of the gel battery. Background Technology

[0002] Lithium-ion batteries are highly favored in portable electronic devices, power batteries, and energy storage due to their high energy density and long cycle life. However, with increasing demands for energy density, safety has become a bottleneck restricting the widespread application and development of lithium-ion batteries. Solid-state batteries, as the next generation of high-energy-density and high-safety batteries, have attracted widespread attention; however, their large interfacial impedance and low ionic conductivity limit their large-scale development and application.

[0003] Gel electrolytes are electrolytes with a special form that lies between liquids and solids. Therefore, gel batteries possess the high ionic conductivity of liquid batteries and the good safety performance of solid-state batteries, making them highly promising for commercial applications. Thermally initiated in-situ polymerization, as one method for preparing gel electrolytes, can utilize the same production equipment as liquid lithium-ion batteries and has been extensively studied by researchers.

[0004] In the production of gel batteries, the impact of monomers and / or initiators on battery performance cannot be ignored, and precise control of the polymerization reaction is quite difficult. If the electrolyte wetting, polymerization, and formation processes are not applied properly, the uniformity of the gel electrolyte distribution in the battery cannot be guaranteed, resulting in high interfacial resistance between the positive and negative electrode materials and the separator, causing lithium plating on the negative electrode. Furthermore, the participation of monomers and / or initiators in the electrolyte in the formation of the SEI film during battery formation can also affect the battery's electrical and safety performance.

[0005] In the preparation of gel batteries, how to effectively combine the gel battery wetting process with the polymerization and formation processes, so as to ensure that the gel electrolyte is fully wetted in the battery and that the polymerized gel electrolyte is evenly distributed between the electrode and the separator, while reducing the influence of the gel components (monomers and / or initiators) on the SEI film formation process, and thus achieve a balance between the electrical performance and safety performance of the gel battery, is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] To address the problems mentioned above in the background art, the purpose of this invention is to provide a gel battery and its preparation method. By improving the wetting, polymerization, and formation processes in the preparation of the gel battery, not only is the wetting effect of the gel electrolyte improved and the internal resistance of the contact interface between the polymerized electrolyte and the electrode reduced, but the influence of monomers, initiators, etc. on the formation of the SEI film during the formation process can also be effectively avoided, thus establishing a stable interface with good performance.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a gel battery includes the following steps:

[0009] Step A1: Injection. The liquid base solution and gel component are simultaneously injected into the battery, resulting in an Init battery. Preferably, the injection specifically involves uniformly mixing the liquid base solution and gel component to obtain a gel electrolyte, which is then injected into the baked battery in one step. The moisture content of the baked battery is required to be <300 ppm, and the dew point of the injection room is controlled at -50 ± 2℃. The liquid base solution includes lithium salt, solvent, and additives. The gel component includes monomers and initiators. The monomers are at least one of polyethylene glycol dimethacrylate, triethylene glycol dimethacrylate, ethylene glycol dimethacrylate, methyl methacrylate, 4,4'-bismaleimide diphenylmethane, and pentaerythritol tetraacrylate. The initiator is one of benzoyl peroxide, azobisisobutyronitrile, and 1-((cyano-1-methylethyl)azo)formamide. The monomer content in the gel electrolyte is 2.0 wt%-12.0 wt%. Furthermore, the lithium salt includes at least one of lithium hexafluorocarbonate, lithium difluorocarbonate, lithium fluoroborate, lithium dioxaborate, and lithium trifluoromethanesulfonate; the solvent includes at least one of methyl ethyl carbonate, diethyl carbonate, propylene carbonate, and fluoroethylene carbonate; and the additive is at least one of vinylene carbonate, vinyl sulfate, and 1,3-propenesulfonate lactone.

[0010] Step A2: Immersion at room temperature. Place the above-mentioned Init battery horizontally in a room temperature environment. The resulting battery is denoted as Inf battery. Preferably, the specific steps of step A2 are as follows: place the battery side seal after liquid injection horizontally in a room temperature settling room for 24-48 hours. The ambient temperature in the settling room is controlled at 25±2℃. The resulting battery is denoted as Inf battery.

[0011] Step A3: High-temperature polymerization. The Inf battery is transferred to a high-temperature environment and placed vertically. The resulting battery is denoted as HG battery. Preferably, in step A3, the Inf battery is transferred to a high-temperature environment with the battery side seal facing upwards. The high-temperature environment temperature is 45-50℃, and the battery is left to stand for 12-24 hours.

[0012] Step A4: High-temperature formation. Maintaining a fixed formation temperature and pressure, charge the HG battery at a constant current charging mode of 0.02-0.05C, controlling the battery termination voltage to 3.0-3.2V. The resulting battery is designated as Form-1. After resting for 5-10 minutes, charge the Form-1 battery at a constant current charging mode of 0.05-0.1C, controlling the battery termination voltage to 3.3-3.5V. The resulting battery is designated as Form-2. After resting for 5-10 minutes, charge the Form-2 battery at a constant current charging mode of 0.1-0.3C, controlling the battery termination voltage to 3.6-3.8V. The resulting battery is designated as Form-3. Preferably, the formation temperature is maintained at a fixed 45±2℃ and the pressure at a fixed 500-1000kgf.

[0013] Step A5: High-temperature aging, the above-mentioned Form-3 battery is placed in a high-temperature environment for static storage; preferably, the specific steps of step A5 are as follows: the above-mentioned Form-3 battery is placed in a high-temperature environment with an ambient temperature of 45±2℃ for static storage for 24-48 hours.

[0014] Step A6: Room temperature capacity grading. The obtained battery is subjected to room temperature capacity grading. Preferably, the specific steps of step A6 are as follows: the battery obtained in step A5 is transferred to a room temperature environment (25±2℃), and first, constant current and constant voltage charging and discharging are performed at 0.33-0.5C, followed by constant current and constant voltage charging and discharging within the range of 1.0-2.0C. The upper limit voltage for charging is set to 4.2-4.35V, and the lower limit voltage for discharging is set to 2.5-2.8V. Wherein, C is the rated capacity of the gel battery.

[0015] Compared to existing technologies, this invention, through a comparative and systematic design and verification of three different polymerization and formation processes for gel batteries, has found a suitable preparation method for gel batteries. The advantages of this invention are: In the preparation method of gel batteries, the liquid base solution and gel components (monomers, initiators) are simultaneously injected, facilitating better and more uniform mixing of the gel components with the liquid base solution, preventing localized uneven distribution of the gel components in the battery, and simplifying operation for easier implementation; The invention employs a room-temperature wetting process to ensure the gel electrolyte exists in liquid form within the battery, which is beneficial for the gel components to fully diffuse into the vicinity of the active material, improving the wetting effect of the gel electrolyte and reducing the interfacial resistance between the polymerized electrolyte and the electrode; The invention uses a high-temperature polymerization process to react and polymerize the monomers and initiators in the liquid electrolyte distributed around the active material, locking the liquid base solution to form a non-flowing gel electrolyte; The invention places the high-temperature polymerization process before high-temperature formation, effectively avoiding the influence of monomers and / or initiators on the formation of the SEI film during the formation process, establishing a stable interface with good performance.

[0016] Furthermore, the superior process methods for gel battery impregnation, polymerization, and formation of this invention are compatible with existing liquid electrolyte battery processes, simplifying the process flow, reducing equipment costs and energy consumption, and facilitating large-scale industrial production. Attached Figure Description

[0017] Figure 1 The above are process flow diagrams for the methods in Group A of Examples 1 to 3.

[0018] Figure 2 The process flow diagrams are for the methods in Group B of Examples 4 to 6.

[0019] Figure 3 The process flow diagrams are for the methods of Group C in Examples 7 to 9. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be emphasized that the embodiments described in this invention are for illustrative purposes and are part of this invention. Based on the embodiments of this invention, those skilled in the art can arbitrarily combine the following embodiments to form new embodiments without creative effort, all of which fall within the scope of protection of this invention.

[0021] In both the embodiments and comparative examples of this invention, the batteries are the same type of 3.5Ah pouch cell, and the positive electrode active material in this battery is LiNi. 0.8 Co 0.1 Mn 0.1 O2; the negative electrode active material is a mixture of silicon suboxide and graphite (mass ratio m) 氧化亚硅 :m 石墨 =1:4); the diaphragm is a polypropylene-based membrane with a surface coated with nano-sized alumina material; the liquid base liquid uses 1M LiPF6 as the electrolyte salt (lithium salt) and a mixture of ethyl methyl carbonate (EMC), propylene carbonate (PC), diethyl carbonate (DEC), and fluoroethylene carbonate (FEC) as the solvent, with a mass ratio of EMC:PC:DEC:FEC = 40:20:30:10. 0.5% vinylene carbonate, 1.0% vinyl sulfate, and 0.5% 1,3-propenesulfonate lactone are added and stirred until homogeneous.

[0022] Example 1

[0023] like Figure 1 As shown, a method for preparing a gel battery, the key processes of which are gel battery impregnation, polymerization, and formation processes, the core idea being to first polymerize the gel components and then perform formation, specifically including the following steps:

[0024] (1) Step A1: Liquid injection. The liquid base liquid and gel components (monomer and initiator) are uniformly mixed to obtain a gel electrolyte. The gel electrolyte is injected into the baked battery in one go. The battery moisture content is required to be <300ppm. The dew point of the injection room is controlled at -50±2℃. The resulting battery is called an Init battery. Among them: the monomer is a mixture of polyethylene glycol dimethacrylate and methyl methacrylate in a mass ratio of 2:1, and the initiator is benzoyl peroxide. The content of monomer in the gel electrolyte is 3.0wt%, and the content of initiator is 0.15wt%.

[0025] (2) Step A2: Immersion at room temperature. Place the Init battery side seal horizontally in a room temperature settling room and let it stand for 24 hours. The ambient temperature in the settling room is controlled at 25±2℃. The resulting battery is called Inf battery.

[0026] (3) Step A3: High temperature polymerization. The Inf battery is transferred to a high temperature environment and placed vertically upward with the side sealed. The temperature of the high temperature environment is 45±2℃. After standing for 12 hours, the battery is recorded as HG battery.

[0027] (4) Step A4: High-temperature formation, keep the formation temperature at 45±2℃ and the pressure at 500kgf, charge the above HG battery with a constant current charging mode of 0.02C, control the battery end voltage to 3.0V, and the resulting battery is recorded as Form-1 battery; after standing for 5 minutes, charge the resulting Form-1 battery with a constant current charging mode of 0.05C, control the battery end voltage to 3.3V, and the resulting battery is recorded as Form-2 battery; after standing for 5 minutes, charge the resulting Form-2 battery with a constant current charging mode of 0.1C, control the battery end voltage to 3.8V, and the resulting battery is recorded as Form-3 battery;

[0028] (5) Step A5: High temperature aging. The Form-3 battery above is placed in a high temperature environment for 24 hours at an ambient temperature of 45±2℃.

[0029] (6) Step A6: At room temperature, transfer the battery obtained in step A5 to a room temperature environment with a temperature of 25±2℃, and perform constant current and constant voltage charging and constant current discharging at 0.33C and 1.0C respectively. Set the upper limit of charging voltage to 4.25V and the lower limit of discharging to 2.5V.

[0030] Example 2

[0031] The difference between this embodiment and Embodiment 1 is that the monomer content in the gel electrolyte used is 5.0 wt%.

[0032] like Figure 1 As shown, the specific steps of the gel battery impregnation, polymerization, and formation processes are the same as in Example 1.

[0033] Example 3

[0034] The difference between this embodiment and Embodiment 1 is that the monomer content in the gel electrolyte used is 8 wt%.

[0035] like Figure 1 As shown, the specific steps of the gel battery impregnation, polymerization, and formation processes are the same as in Example 1.

[0036] Example 4

[0037] The electrolyte used is a gel electrolyte with a monomer content of 3.0 wt%. The difference between this embodiment and Embodiments 1-3 lies in the process method used. The main difference is that a two-step liquid injection method is adopted, in which the gel component is added to the battery after formation, that is, formation is performed first and then gel polymerization occurs.

[0038] like Figure 2 As shown, a method for preparing a gel battery specifically includes the following steps:

[0039] (1) Step B1: First step of liquid injection, inject 85wt% liquid base liquid into the baked battery. The battery moisture requirement is <300ppm. The dew point of the injection room is controlled at -50±2℃. The resulting battery is called Init-1 battery.

[0040] (2) Step B2: High temperature immersion. The Init-1 battery was transferred to a high temperature environment and placed vertically upward with the side sealed. The high temperature environment temperature was 45±2℃. The battery was left to stand for 24 hours. The resulting battery was called HS battery.

[0041] (3) Step B3: High-temperature formation, keep the formation temperature at 45±2℃ and the pressure at 500kgf, charge the above HG battery with a constant current charging mode of 0.02C, control the battery end voltage to 3.0V, and the resulting battery is recorded as Form-1B battery; after standing for 5 minutes, charge the resulting Form-1B battery with a constant current charging mode of 0.05C, control the battery end voltage to 3.3V, and the resulting battery is recorded as Form-2B battery; after standing for 5 minutes, charge the resulting Form-2B battery with a constant current charging mode of 0.1C, control the battery end voltage to 3.8V, and the resulting battery is recorded as Form-3B battery;

[0042] (4) Step B4: Second step of liquid injection, after mixing 15wt% of liquid base liquid and gel components (monomer and initiator) evenly, inject into Form-3B battery. The dew point of the injection room is controlled at -50±2℃. The resulting battery is called Init-2 battery. The types and amounts of monomers and initiators in the gel components are the same as in Example 1.

[0043] (5) Step B5: Immersion at room temperature. Place the Init-2 battery side seal horizontally in a room temperature settling room and let it stand for 24 hours. The ambient temperature in the settling room is controlled at 25±2℃. The resulting battery is called Inf-B battery.

[0044] (6) Step B6: High temperature polymerization. The Inf-B battery is transferred to a high temperature environment and placed vertically upward with the side sealed. The high temperature environment temperature is 45±2℃. After standing for 12 hours, the battery is recorded as HG-B battery.

[0045] (7) Step B7: At room temperature, transfer the battery obtained in step B6 to a room temperature environment with a temperature of 25±2℃, and perform constant current and constant voltage charging and constant current discharging at 0.33C and 1.0C respectively. Set the upper limit of charging voltage to 4.25V and the lower limit of discharging to 2.5V.

[0046] Example 5

[0047] The difference between this embodiment and Embodiment 4 is that the monomer content in the gel electrolyte used is 5.0 wt%.

[0048] like Figure 2 As shown, the specific steps of the gel battery impregnation, polymerization, and formation processes are the same as in Example 4.

[0049] Example 6

[0050] The difference between this embodiment and Embodiment 4 is that the monomer content in the gel electrolyte used is 8 wt%.

[0051] like Figure 2 As shown, the specific steps of the gel battery impregnation, polymerization, and formation processes are the same as in Example 4.

[0052] Example 7

[0053] The electrolyte used is a gel electrolyte with a monomer content of 3.0 wt%. The difference between this example and Examples 1-3 and Examples 4-6 lies in the different process methods used, mainly in that the polymerization and formation processes of the gel component are carried out simultaneously.

[0054] like Figure 3 As shown, a method for preparing a gel battery specifically includes the following steps:

[0055] (1) Step C1: Liquid injection. After uniformly mixing the liquid base liquid with the gel components (monomers and initiators), it is injected into the baked battery in one go. The battery moisture content is required to be <300ppm. The dew point of the injection room is controlled at -50±2℃. The resulting battery is called an Init-C battery. The types and amounts of monomers and initiators in the gel components are the same as in Example 1.

[0056] (2) Step C2: Immersion at room temperature. Place the Init-B battery side seal horizontally in a room temperature settling room and let it stand for 24 hours. The ambient temperature in the settling room is controlled at 25±2℃. The resulting battery is called Inf-C battery.

[0057] (3) Step C3: High-temperature formation / polymerization, keeping the formation temperature at 45±2℃ and the pressure at 500kgf, charging the above HG battery with a constant current charging mode of 0.02C, controlling the battery end voltage to 3.0V, the resulting battery is recorded as Form-1C battery; after standing for 5 minutes, charging the resulting Form-1C battery with a constant current charging mode of 0.05C, controlling the battery end voltage to 3.3V, the resulting battery is recorded as Form-2C battery; after standing for 5 minutes, charging the resulting Form-2C battery with a constant current charging mode of 0.1C, controlling the battery end voltage to 3.8V, the resulting battery is recorded as Form-3C battery;

[0058] (4) Step C4: High temperature aging. The above Form-3C battery is placed in a high temperature environment for 24 hours. The ambient temperature is 45±2℃.

[0059] (5) Step C5: At room temperature, the battery obtained in step C4 is transferred to a room temperature environment with a temperature of 25±2℃, and constant current and constant voltage charging and constant current discharging are performed at 0.33C and 1.0C respectively. The upper limit of charging voltage is set to 4.25V and the lower limit of discharging voltage is set to 2.5V.

[0060] Example 8

[0061] The difference between this embodiment and Embodiment 7 is that the monomer content in the gel electrolyte used is 5.0 wt%.

[0062] like Figure 3 As shown, the specific steps of the gel battery impregnation, polymerization, and formation processes are the same as in Example 7.

[0063] Example 9

[0064] The difference between this embodiment and Embodiment 7 is that the monomer content in the gel electrolyte used is 8.0 wt%.

[0065] like Figure 3 As shown, the specific steps of the gel battery impregnation, polymerization, and formation processes are the same as in Example 7.

[0066] Comparative Example 1

[0067] The electrolyte is a liquid electrolyte, that is, a simple liquid base liquid without gel components.

[0068] like Figure 1As shown, the specific steps of the gel battery impregnation, polymerization, and formation processes are the same as in Example 1.

[0069] Comparative Example 2

[0070] The electrolyte is a liquid electrolyte, that is, a simple liquid base liquid without gel components.

[0071] like Figure 2 As shown, the specific steps of the gel battery impregnation, polymerization, and formation processes are the same as in Example 4.

[0072] Comparative Example 3

[0073] The electrolyte is a liquid electrolyte, that is, a simple liquid base liquid without gel components.

[0074] like Figure 3 As shown, the specific steps of the gel battery impregnation, polymerization, and formation processes are the same as in Example 7.

[0075] The batteries were fully charged and disassembled after capacity testing to observe the gel distribution, the appearance of the negative electrode, and the "lithium plating" state on the surface. The results are shown in Table 1.

[0076] Table 1 Results of disassembly after full-charge battery capacity testing.

[0077]

[0078]

[0079] Cell performance testing includes: initial efficiency, initial internal resistance, and capacity retention after 100 charge-discharge cycles at 25℃ and 0.5C / 1C. Each test group consists of at least two lithium-ion batteries, and the average value is taken.

[0080] 25℃ Cyclic Performance Test: Take the lithium-ion battery after capacity testing, charge it at 0.5C to 4.25V, then switch to constant voltage charging until the charging current is ≤ cutoff current, let it stand for 30 minutes, then discharge it at 1C to the cutoff voltage of 2.5V, let it stand for 30 minutes, and perform the charge and discharge test according to the above procedure. A total of 100 cycles were performed. The test results are shown in Table 2.

[0081] Table 2 Cell performance test results

[0082] plan Average first effect Initial internal resistance (mΩ) Capacity retention after 100 cycles at 25°C Example 1 84.20％ 28.1 95.58％ Example 2 84.15％ 28.8 95.49％ Example 3 83.29％ 29.9 94.29％ Example 4 84.14％ 28.0 95.50％ Example 5 83.43％ 29.7 95.17％ Example 6 81.18％ 32.6 91.28％ Example 7 83.97％ 29.3 95.11％ Example 8 82.87％ 30.3 94.12％ Example 9 81.50％ 31.8 91.90％ Comparative Example 1 84.25％ 27.2 95.63％ Comparative Example 2 84.29％ 27.0 95.78％ Comparative Example 3 84.22％ 27.5 95.54％

[0083] To facilitate a more intuitive and clear analysis and understanding, the examples and comparative examples are divided into three groups: Group A: Examples 1-3 and Comparative Example 1; Group B: Examples 4-6 and Comparative Example 2; Group C: Examples 7-9 and Comparative Example 3. Examples 1-9 are further divided into three groups: Group 1: Examples 1, 4, and 7; Group 2: Examples 2, 5, and 8; Group 3: Examples 3, 6, and 9.

[0084] Comparing Groups A, B, and C, corresponding to three impregnation and polymerization / formation processes (Method A, Method B, and Method C respectively), it can be seen that the fully charged disassembly of the negative electrode interface and cell performance of the gel electrolyte in Group A are closest to the negative electrode interface state of the comparative liquid electrolyte. Overall, it is significantly better than Groups B and C. In this case, the impact of the impregnation and polymerization / formation processes on the gel battery is greater than the impact of increasing the monomer ratio, indicating that the process approach of forming gel first and then forming is more suitable for gel batteries. Comparing Groups 1, 2, and 3, corresponding to three ranges of gel monomer ratios (3.0 wt%, 5.0 wt%, and 8.0 wt%), it can be seen that as the monomer ratio in the electrolyte increases, the fully charged disassembly of the negative electrode interface and cell performance of the gel battery significantly deteriorate. In this case, the impact of increasing the monomer ratio on the gel battery is greater than the impact of the impregnation and polymerization / formation processes, indicating that the in-situ polymerization method is not suitable for adding high monomer content, as it is not conducive to the uniform distribution of the gel electrolyte in the battery. Furthermore, for low-proportion cells, the fully charged disassembly of the negative electrode interface and cell performance using method B are superior to those using method C. However, for high-proportion cells, the fully charged disassembly of the negative electrode interface and cell performance using method B are inferior to those using method C. This is because method B uses a two-step electrolyte injection method, in which the gel component is added in the second step. The gel electrolyte of low-proportion cells can be better dispersed in the battery, and at the same time, it effectively avoids the adverse effects of the gel component on the formation of the SEI film during the battery formation process. On the other hand, a high proportion of cells will lead to a significant increase in electrolyte viscosity, which is not conducive to the diffusion of the gel component in the battery. This can be seen from the data comparison of Examples 4, 5, 7, 8, 6, and 9.

[0085] Heating Test: Four cells from each embodiment and comparative example were fully charged and fixed with a special metal clamp. Temperature sensors were connected to the positive and negative tabs, the large surface area, and the explosion-proof valve of the cells. The cells were then left to stand at 60°C for 4 hours, then heated to 130°C at a rate of 2°C / min and held for 30 minutes. The temperature was then increased to 200°C at a rate of 2°C / min and held for 30 minutes. The temperature rise curves at different locations of the cells were monitored during the heating process, and the maximum values ​​of the temperature rise curves at different locations were recorded. The results are shown in Table 3.

[0086] Table 3 shows the highest temperature of the battery cell at different locations during the heating process.

[0087]

[0088]

[0089] As shown in Table 3, the highest point temperature of the gel electrolyte batteries in Examples 1-9 during the heating process was significantly lower than that of the liquid electrolyte batteries in Comparative Examples 1-3, indicating that the gel electrolyte batteries have better safety performance. Meanwhile, compared to Examples 4-6 and 7-9, Examples 1-3 showed lower highest point temperatures of the heating curves at different locations during the heating process, indicating that the process approach of forming a gel first and then performing the formation in Method A is more suitable for gel batteries. From the comparison of Examples 1, 2, and 3, it can be seen that the safety performance of the gel battery improved with the increase of the single-cell ratio. However, combined with the cell performance test results in Table 2, the gel battery in Example 2 with a single-cell ratio of 5.0 wt% better balanced electrochemical performance and safety performance.

[0090] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and design concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a gel battery, characterized in that: Includes the following steps: Step A1: Liquid injection, the liquid base liquid and gel component are injected into the battery at the same time, and the resulting battery is called the Init battery; Step A2: Immersion at room temperature. Place the above Init battery horizontally in a room temperature environment. The resulting battery is denoted as Inf battery. Step A3: High-temperature polymerization. The Inf battery is transferred to a high-temperature environment and placed vertically. The resulting battery is denoted as HG battery. The temperature of the high-temperature environment is 45-50℃. The placement time is 12-24 hours. Step A4: High-temperature formation, maintaining a constant formation pressure, the HG battery is formed in a high-temperature environment of 43-47℃; the formation pressure is 500-1000 kg. Step A5: High-temperature aging. After the formation process is completed, the battery is placed in a high-temperature environment for resting. The temperature of the high-temperature environment is 43-47℃. Step A6: Capacity testing at room temperature. The obtained battery is then subjected to capacity testing at room temperature to obtain a gel battery. In step A4, the method for charging the HG battery during the high-temperature formation process is as follows: The HG battery is charged at a constant current charging mode of 0.02-0.05C, controlling the battery's final voltage to 3.0-3.2V. The resulting battery is designated as Form-1. After resting for 5-10 minutes, the Form-1 battery is charged at a constant current charging mode of 0.05-0.1C, controlling the final voltage to 3.3-3.5V. The resulting battery is designated as Form-2. After resting for 5-10 minutes, the Form-2 battery is charged at a constant current charging mode of 0.1-0.3C, controlling the final voltage to 3.6-3.8V. The resulting battery is designated as Form-3.

2. The method for preparing a gel battery according to claim 1, characterized in that: In step A1, the liquid injection specifically involves uniformly mixing the liquid base liquid with the gel component to obtain a gel electrolyte, and then injecting the gel electrolyte into the baked battery in one go. The resulting battery is referred to as an Init battery.

3. The method for preparing a gel battery according to claim 2, characterized in that: The moisture content of the baked battery must be <300ppm, and the dew point of the environment in the filling room must be controlled at -50±2℃.

4. The method for preparing a gel battery according to claim 2, characterized in that: The liquid base solution includes lithium salt, solvent, and additives; the gel component includes monomers and initiators, wherein the monomers are at least one selected from polyethylene glycol dimethacrylate, triethylene glycol dimethacrylate, ethylene glycol dimethacrylate, methyl methacrylate, 4,4'-bismaleimide diphenylmethane, and pentaerythritol tetraacrylate; the initiator is one selected from benzoyl peroxide, azobisisobutyronitrile, and 1-((cyano-1-methylethyl)azo)formamide; and the monomer content in the gel electrolyte is 2.0 wt%-12.0 wt%.

5. The method for preparing a gel battery according to claim 1, characterized in that: In step A2, the Init battery side seal is placed horizontally in a room at room temperature for 24-48 hours.

6. The method for preparing a gel battery according to claim 1, characterized in that: In step A3, the Inf battery side seal is placed vertically upwards.

7. The method for preparing a gel battery according to claim 1, characterized in that: In step A5, the settling time is 24-48 hours.

8. The method for preparing a gel battery according to claim 1, characterized in that: The specific steps of step A6 are as follows: the battery obtained in step A5 is transferred to a room temperature environment, with a temperature of 25±2℃. First, constant current and constant voltage charging and constant current discharging are performed at 0.33-0.5C, followed by constant current and constant voltage charging and constant current discharging at 1.0-2.0C. The upper limit of the charging voltage is set to 4.2-4.35V, and the lower limit of the discharging voltage is set to 2.5-2.8V; where C is the rated capacity of the gel battery.

9. A gel battery, characterized in that: The gel battery is prepared using the preparation method described in any one of claims 1 to 8.

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