Preparation method of high-safety mobile power supply battery

Abstract

The application discloses a kind of preparation methods of high safety mobile power supply battery, it is related to mobile power supply battery technical field, comprising: step S1, preparation positive plate;Step S2, first polymer, second polymer are dissolved in NMP according to proportion to form prepolymer precursor solution, prepolymer precursor solution is sprayed on PP diaphragm, and drying treatment is carried out at 60~80 ℃ temperature, then form gelatinous diaphragm;Step S3, after graphite, Si / C, SP, CNT, SBR, PAA are mixed according to proportion, add water and stir evenly, then drying treatment is carried out at 90~110 ℃ temperature, after rolling, cutting obtains negative plate;Step S4, positive plate, gelatinous diaphragm, negative plate are laminated, and liquid injection is formed and high temperature and high pressure aging, and high-energy battery is prepared.The application forms three-dimensional polymer network structure by in-situ polymerization, improves the interface compatibility of gelatinous diaphragm and positive and negative, inhibits lithium dendrite growth, simultaneously improves the ionic conductivity and mechanical strength of gelatinous diaphragm.

Description

Technical Field

[0001] This invention relates to the field of mobile power bank battery technology, specifically a method for preparing a highly safe mobile power bank battery. Background Technology

[0002] As a core component of next-generation high-energy-density and high-safety lithium-ion batteries, gel polymer electrolytes (EPEs) face challenges in their development, including poor interface compatibility, difficulty in balancing ionic conductivity and mechanical strength, and high costs associated with large-scale manufacturing. To address these issues, the following solutions are proposed: First, focusing on interface optimization by developing active interface repair technologies such as in-situ polymerization to generate a gel layer in situ to stabilize the electrode / electrolyte interface; second, optimizing materials and structures by constructing a porous three-dimensional cross-linked framework at the separator-electrode interface to synergistically improve ion transport efficiency and mechanical stability; and third, optimizing the preparation process by blending LMFPs with slurry and employing double-layer coating processes to achieve ultra-thin, uniform, and low-cost electrode manufacturing.

[0003] For example, the patent with announcement number CN120566001B describes a high-safety separator for new energy batteries and its preparation method, which realizes systematic collaborative innovation of materials, processes and equipment, and thus realizes the commercialization of high-energy-density lithium-ion batteries. However, the preparation process in this scheme is relatively complex, and the gel separator has low ionic conductivity and insufficient mechanical strength, which is of limited help for the cell needle penetration test.

[0004] Based on this, a method for preparing a highly safe mobile power bank battery is now provided, which can eliminate the drawbacks of existing technical solutions. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a highly safe mobile power battery, in order to solve the problems of low ionic conductivity, insufficient mechanical strength, and limited assistance in the needle penetration test of the battery cell in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a highly safe mobile power bank battery specifically includes the following steps: Step S1: Prepare the positive electrode sheet; Step S2: Dissolve the first polymer and the second polymer in NMP in a certain proportion to form a prepolymer precursor solution. Spray the prepolymer precursor solution onto the PP membrane and dry it at a temperature of 60~80°C to form a gel membrane. Step S3: Mix graphite, Si / C, SP, CNT, SBR and PAA in proportion, add water and stir evenly, then dry at 90~110℃, and obtain negative electrode sheet by rolling and slitting. Step S4: Stack the positive electrode, gel separator, and negative electrode, and perform liquid injection formation and high-temperature and high-pressure aging to prepare a high-energy battery cell; Specifically, step S1 includes: Step S11: Add LMFP powder to NMP, then add GMA and stir for 12 hours, then add SP and stir for 12 hours to obtain LMFP slurry containing prepolymer; Step S12: Prepare slurry A by mass ratio NCM:SP:CNT:PVDF=95:1.5:0.5:3, and prepare slurry B by mass ratio NCM:LMFP:SP:CNT:PVDF=80:15:1.5:0.5:3, wherein LMFP in slurry B is LMFP slurry containing prepolymer; Step S13: Apply slurry A and slurry B to the composite aluminum foil simultaneously using a dual-module nozzle. Slurry B is applied to the side of the positive electrode near the gel membrane to form layer B, and slurry A is applied to the side of the positive electrode near the composite aluminum foil to form layer A. After the coating operation, the electrode is dried at 90°C and then rolled and slit to obtain the positive electrode sheet.

[0007] Further, step S4 specifically includes: adding 1% of an initiator to the electrolyte during the liquid injection formation process; maintaining the temperature at 85°C and the pressure at 2~5 MPa during the high temperature and high pressure aging process to ensure that the prepolymer precursor solution sprayed on the surface of the gel separator polymerizes with the prepolymer in the LMFP slurry in the positive electrode to form a stable three-dimensional polymer network structure.

[0008] Further, in step S11, the LMFP slurry is prepared at a mass ratio of LMFP:SP:GMA = 95:1:4.

[0009] Furthermore, in step S11, the amount of NMP added is 150g of NMP for every 95g of LMFP powder.

[0010] Furthermore, in step S13, the coating thickness ratio of layer A to layer B is 1:0.5, and the viscosity ratio is 1.2:1.

[0011] Furthermore, the positive electrode active material of the positive electrode sheet in step S13 is not limited to NCM, but also includes any one of LCO and LFP.

[0012] Further, in step S2, the ratio of the first polymer to the second polymer is set to 0.5:1.5, where the first polymer is polyethylene glycol methyl ether methacrylate and the second polymer is lithium N-trifluoromethanesulfonyl p-styrenesulfonylimide and its derivatives.

[0013] Furthermore, in step S2, the thickness of the PP diaphragm is 5~10μm.

[0014] Furthermore, in step S3, the ratio of graphite, Si / C, SP, CNT, SBR and PAA is set to 80:15:1:0.5:1:1.5.

[0015] Furthermore, the initiator is any one of AIBN, ABVN, BPO, DCP, and TBPB.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for preparing a highly safe mobile power battery. By introducing polymers into the conventional cell structure, safety is improved. The method involves spraying a lithium-ion conductive polymer and a long-chain polymer that increases the thermal stability and flexibility of the separator onto the separator surface. During the aging process, these polymers are polymerized with the prepolymer pre-added in the LMFP slurry, forming a safe and stable three-dimensional network structure on the positive electrode side. This improves the interfacial compatibility between the gel separator and the positive and negative electrodes, inhibits lithium dendrite growth, and simultaneously enhances the ionic conductivity and mechanical strength of the gel separator. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the preparation method of the present invention.

[0018] Figure 2 This is a schematic diagram of step S1 of the present invention.

[0019] Figure 3 This is a schematic diagram of the structure of the mobile power battery of the present invention.

[0020] Figure 4 This is a schematic diagram of the structure of glycidyl methacrylate of the present invention.

[0021] Figure 5 This is a schematic diagram of the structure of polyethylene glycol methyl ether methacrylate of the present invention.

[0022] Figure 6 This is a schematic diagram of the structure of lithium styrenesulfonyl (trifluoromethanesulfonyl)imide of the present invention.

[0023] Figure labeling: Positive electrode 10, Layer A 11, Layer B 12, Gel diaphragm 20, Diaphragm 21, Negative electrode 30. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] To address the safety issues related to needle penetration and thermal shock in current high-energy-density power banks, this invention introduces a multi-layer coating process during production. By constructing a flexible interface layer rich in functional additives on both sides of the gel separator 20, it helps to improve the rigid contact between the gel separator 20 and the positive electrode, improves interface compatibility, and inhibits lithium dendrite growth, thereby significantly improving the energy density and safety of the battery. Simultaneously, a prepolymer mixed with LMFP is constructed by double-layer coating on the positive electrode side. In addition, a prepolymer precursor solution is sprayed onto the surface of the gel separator 20, and a trace amount of initiator is added to the electrolyte. Its advantage stems from the unique dynamic cross-linked network structure built inside the cell, which can synergistically improve ionic conductivity and mechanical strength. Through this combined design, this invention can produce a high-safety, high-energy-density (280~340Wh / kg) battery cell, as detailed below.

[0026] Among them, such as Figure 1 and Figure 2 As shown, this invention provides a method for preparing a highly safe mobile power bank battery, specifically including the following steps: Step S1: Prepare positive electrode 10; Step S2: Dissolve the first polymer and the second polymer in NMP in a certain proportion to form a prepolymer precursor solution. Spray the prepolymer precursor solution onto the PP membrane and dry it at 60~80℃ to form a gel membrane 20. Specifically, step S2 includes: setting the ratio of the first polymer to the second polymer to 0.5:1.5, wherein the first polymer is polyethylene glycol methyl ether methacrylate (PEGMEMA-like structure: CH2=C(R)). 1 )-C(O)-O-(CH2CH2O)nR 2 The first polymer serves to form a chain-like network structure to increase the adhesion of the gel membrane 20. The long-chain structure of PEGMEMA can better increase the adhesion of LiSTFSI and GMA after polymerization and improve the problem of its high brittleness after polymerization. LiSTFSI can increase the lithium-ion conductivity of the membrane 21 and avoid the decrease in cell ion conductivity caused by the addition of polymer. GMA can be used as an LMFP dispersant. Its adsorption on the LMFP surface can form a stable three-dimensional network structure with the gel membrane 20 in the subsequent aging polymerization step, protecting the positive electrode structure. The second polymer is N-trifluoromethanesulfonyl p-styrenesulfonyl (trifluoromethanesulfonyl)imide lithium (LiSTFSI) and its derivatives (similar structure F3-SO2-N). - (Li + The second polymer (PP membrane) increases ionic conductivity and improves the high-temperature resistance of the gel membrane 20. The thickness of the PP membrane is 5~10μm. A schematic diagram of the structure of polyethylene glycol methyl ether methacrylate is shown below. Figure 5As shown in the diagram, the structural schematic of lithium styrenesulfonyl (trifluoromethanesulfonyl)imide is as follows: Figure 6 As shown; Step S3: Mix graphite, Si / C, SP, CNT, SBR and PAA in proportion, add water and stir evenly, then dry at 90~110℃, and obtain negative electrode sheet 30 by rolling and slitting. Specifically, step S3 includes: graphite, Si / C (SiO2) X (X takes values ​​from 0.5 to 1.5), and the ratio of SP, CNT, SBR, and PAA is set to 80:15:1:0.5:1:1.5; Step S4: The positive electrode 10, gel separator 20, and negative electrode 30 are stacked, and liquid injection formation and high-temperature and high-pressure aging are performed to prepare a high-energy battery cell. The structural schematic diagram of the high-energy battery cell is shown below. Figure 3 As shown; Specifically, step S4 includes: during the liquid injection formation process, adding 1% of an initiator to the electrolyte; during the high temperature and high pressure aging process, maintaining the temperature at 85°C and the pressure at 2~5 MPa to ensure that the prepolymer precursor solution sprayed on the surface of the gel separator 20 polymerizes with the prepolymer in the LMFP slurry in the positive electrode 10 to form a stable three-dimensional polymer network structure; the initiator is any one of AIBN, ABVN, BPO, DCP and TBPB; the prepolymer refers to a polymer or monomer with a low molecular weight containing polymerizable functional groups (such as carbon-carbon double bonds and epoxy groups); Specifically, step S1 includes: Step S11: Add LMFP (lithium manganese iron phosphate) powder to NMP (N-methylpyrrolidone), then add GMA (glycidyl methacrylate, similar structure CH2=C(R)). 1 )-C(O)-OR 2 Stir for 12 hours, then add SP (acetylene black, conductive agent) and stir for another 12 hours to obtain an LMFP slurry containing prepolymer. The LMFP slurry is prepared at a mass ratio of LMFP:SP:GMA = 95:1:4. The amount of NMP added is 150g NMP for every 95g LMFP powder. GMA is used as a dispersant and copolymerizes with the monomers on the membrane to form a three-dimensional structure. The structural diagram of GMA is shown below. Figure 4 As shown; Step S12: Prepare slurry A by mass ratio NCM(811):SP:CNT:PVDF=95:1.5:0.5:3, and prepare slurry B by mass ratio NCM(811):LMFP:SP:CNT:PVDF=80:15:1.5:0.5:3. In slurry B, LMFP is LMFP slurry containing prepolymer, NCM(811) is lithium nickel cobalt manganese oxide (811 type), and the mass ratio of its core metal elements nickel (Ni), cobalt (Co), and manganese (Mn) is 8:1:1. SP can be used as a positive electrode conductive agent to compensate for the positive electrode activity. To address the issue of insufficient conductivity in the materials (NCM811, LMFP), the electron conduction efficiency of the positive electrode 10 is improved, ensuring a full and uniform electrochemical reaction and reducing the internal resistance of the cell. CNT, carbon nanotubes, can work synergistically with SP as a positive electrode composite conductive agent to further improve the conductivity and structural stability of the positive electrode 10, ensuring the energy density of the cell. PVDF, polyvinylidene fluoride, is a special binder for lithium-ion battery positive electrodes, which can bond NCM811, LMFP, SP, CNT and other materials in the positive electrode together, while firmly bonding the entire positive electrode active layer to the composite aluminum foil substrate. Step S13: A slurry and B slurry are simultaneously coated onto the composite aluminum foil using a dual-module nozzle. Slurry B is coated on the side of the positive electrode closest to the gel separator 20 to form layer B 12, and slurry A is coated on the side of the positive electrode closest to the composite aluminum foil to form layer A 11. After coating, the electrode is dried at 90°C. The resulting positive electrode sheet 10 is obtained by rolling and slitting. The coating thickness ratio of layer A 11 to layer B 12 is 1:0.5, and the viscosity ratio is 1.2:1. The positive electrode sheet 10... The active material is not limited to NCM, but also includes any one of LCO and LFP. Composite aluminum foil is aluminum foil with a conductive coating on the surface. Foil refers to ultra-thin metal sheets with high conductivity and high ductility. It is the core substrate of the positive and negative electrode sheets of the battery, used to carry active materials and conduct current. Positive electrode foil is usually pure aluminum foil, which is the conventional substrate material of the positive electrode of the battery. Negative electrode foil is usually pure copper foil, used to carry negative electrode active materials (such as graphite, Si / C composite materials). Specifically, LMFP slurry is incorporated into the B layer 12 of the positive electrode near the separator 21, forming a bilayer structure with the compacted A layer 11 (pure positive electrode active material), replacing the traditional single positive electrode layer design. This solves the problem of rigid contact between the traditional gel separator 20 and the positive electrode, inhibits lithium dendrite growth, and structurally reduces the risk of internal short circuits. The LMFP slurry contains prepolymer components such as GMA (glycidyl methacrylate). GMA is adsorbed on the surface of LMFP powder. During the in-situ polymerization stage of cell electrolyte aging, it can copolymerize with prepolymers such as PEGMEMA and LiSTFSI sprayed on the surface of the gel separator 20, forming a continuous and stable three-dimensional polymer network structure at the positive electrode-separator interface. This structure can protect the structural integrity of the positive electrode active material on the one hand, and tightly bond the gel separator 20 to the positive electrode sheet 10 on the other hand, avoiding ion transport failure caused by interface separation.

[0027] In summary, this invention provides a method for preparing a high-safety mobile power battery, which involves spraying a prepolymer protective layer onto both sides of the gel separator 20 and using a double-layer coating process. The side closer to the composite aluminum foil uses a high-pressure compacted positive electrode active material without admixture, while the side closer to the gel separator 20 uses a B slurry with LMFP and prepolymer admixture. In-situ polymerization is carried out during the liquid injection aging process. The gel separator 20, positive electrode 10, and negative electrode 30 form a gel layer with a fast lithium-ion channel. During the needle penetration test, this gel layer partially wraps the outer layer of the steel needle, avoiding excessive contact between the copper foil (negative electrode foil) and the aluminum foil (positive electrode foil), and reducing the probability of thermal runaway caused by a large amount of heat generated in a short time.

[0028] To further demonstrate the application value of the high-safety mobile power battery preparation method of the present invention, experimental data of preparing corresponding mobile power batteries with different parameters are provided below, as shown in the following examples and comparative examples. Example

[0029] This embodiment prepares a highly safe mobile power battery using the above method, and the steps include: Step S1: Set the ratio of LMFP, SP, and GMA to 95:1:4. Add 95g of LMFP (lithium manganese iron phosphate) powder to 150g of NMP, then add 4g of GMA (glycidyl methacrylate) and stir for 12 hours. Then add 1g of NMP... SP (acetylene black) was stirred for 12 hours to obtain LMFP slurry containing prepolymer. Slurry A was prepared by mass ratio NCM(811):SP:CNT:PVDF=95:1.5:0.5:3. Slurry B was prepared by mass ratio NCM(811):LMFP:SP:CNT:PVDF=80:15:1.5:0.5:3. LMFP in slurry B is LMFP slurry containing prepolymer. Slurry A and slurry B were coated on composite aluminum foil simultaneously through a dual-module nozzle. Slurry B was coated on the side of the positive electrode near the gel membrane to form layer B, and slurry A was coated on the side of the positive electrode near the composite aluminum foil to form layer A. The thickness ratio of layer A to layer B was 1:0.5, and the viscosity ratio was 1.2:1. Both were coated on composite aluminum foil at the same time. After coating, the foil was dried at 90°C. After rolling and cutting, the positive electrode sheet was obtained. Step S2: Dissolve the first polymer and the second polymer in NMP at a ratio of 0.5:1.5 to form a prepolymer precursor solution. The first polymer is polyethylene glycol methyl ether methacrylate, and the second polymer is lithium styrene sulfonyl (trifluoromethanesulfonyl)imide (LiSTFSI). Spray the prepolymer precursor solution onto a PP membrane with a thickness of 5~10μm and dry it at a temperature of 60~80℃ to form a gel membrane. Step S3: Add graphite and Si / C (SiO2) X The following ingredients are mixed in a ratio of 80:15:1:0.5:1:1.5 (X is 0.5~1.5), SP, CNT, SBR and PAA are mixed, water is added and stirred evenly, and then dried at 90~110℃. After rolling and slitting, the negative electrode sheet is obtained. Step S4: Stack the positive electrode, gel separator, and negative electrode, and perform liquid injection formation and high-temperature and high-pressure aging. During the liquid injection formation process, add 1% initiator to the electrolyte. During the high-temperature and high-pressure aging process, maintain the temperature at 85℃ and the pressure at 2~5 MPa for 12 hours to ensure that the prepolymer precursor solution sprayed on the surface of the gel separator polymerizes with the prepolymer in the LMFP slurry in the positive electrode to form a stable three-dimensional polymer network structure, thereby preparing a high-energy battery cell. The initiator is any one of AIBN, ABVN, BPO, DCP, and TBPB. Specifically, the prepared cell structure is as follows: Figure 3As shown in Table 1, the high-energy battery cell was subjected to a needle penetration test. The relevant data of the battery cell obtained from the test are shown in Table 1. The battery cell energy density is 322Wh / kg, the capacity is 5.0Ah, the highest temperature of the hot box test is 134℃, and the highest temperature of the needle penetration test is 25.5℃. Example

[0030] This embodiment prepares a highly safe mobile power battery using the above method, and the steps include: Step S1: Set the ratio of LMFP, SP, and GMA to 95:1:4. Add 95g of LMFP (lithium manganese iron phosphate) powder to 150g of NMP, then add 4g of GMA (glycidyl methacrylate) and stir for 12 hours. Then add 1g of NMP... SP (acetylene black) was stirred for 12 hours to obtain LMFP slurry containing prepolymer. Slurry A was prepared by mass ratio NCM(811):SP:CNT:PVDF=95:1.5:0.5:3. Slurry B was prepared by mass ratio NCM(811):LMFP:SP:CNT:PVDF=80:15:1.5:0.5:3. LMFP in slurry B is LMFP slurry containing prepolymer. Slurry A and slurry B were coated on composite aluminum foil simultaneously through a dual-module nozzle. Slurry B was coated on the side of the positive electrode near the gel membrane to form layer B, and slurry A was coated on the side of the positive electrode near the composite aluminum foil to form layer A. The thickness ratio of layer A to layer B was 1:0.5, and the viscosity ratio was 1.2:1. Both were coated on composite aluminum foil at the same time. After coating, the foil was dried at 90°C. After rolling and cutting, the positive electrode sheet was obtained. Step S2: Dissolve the first polymer and the second polymer in NMP at a ratio of 0.5:1.5 to form a prepolymer precursor solution. The first polymer is polyethylene glycol methyl ether methacrylate, and the second polymer is lithium styrene sulfonyl N-[(trifluoromethyl)oxo[[(trifluoromethyl)sulfonyl]amino]-4-sulfonyl]imine (LiSsTFSI). Spray the prepolymer precursor solution onto a PP membrane with a thickness of 5~10μm and dry it at a temperature of 60~80℃ to form a gel membrane. Step S3: Add graphite and Si / C (SiO2) X The following ingredients are mixed in a ratio of 80:15:1:0.5:1:1.5 (X is 0.5~1.5), SP, CNT, SBR and PAA are mixed, water is added and stirred evenly, and then dried at 90~110℃. After rolling and slitting, the negative electrode sheet is obtained. Step S4: Stack the positive electrode, gel separator, and negative electrode, and perform liquid injection formation and high-temperature and high-pressure aging. During the liquid injection formation process, add 1% initiator to the electrolyte. During the high-temperature and high-pressure aging process, maintain the temperature at 85℃ and the pressure at 2~5 MPa for 12 hours to ensure that the prepolymer precursor solution sprayed on the surface of the gel separator polymerizes with the prepolymer in the LMFP slurry in the positive electrode to form a stable three-dimensional polymer network structure, thereby preparing a high-energy battery cell. The initiator is any one of AIBN, ABVN, BPO, DCP, and TBPB. This embodiment is consistent with the preparation method, steps, and parameters of Example 1, except that the second polymer is lithium styrenesulfonyl N-[(trifluoromethyl)oxo[[(trifluoromethyl)sulfonyl]amino]-4-sulfonyl]imine (LiSsTFSI); Specifically, the prepared cell structure is as follows: Figure 3 As shown in Table 1, the cell was subjected to a needle penetration test. The cell energy density was 323Wh / kg, the capacity was 5.1Ah, the highest temperature of the hot box test was 135℃, and the highest temperature of the needle penetration test was 26.5℃. Example

[0031] This embodiment prepares a highly safe mobile power battery using the above method, and the steps include: Step S1: Set the ratio of LMFP, SP, and GMA to 95:1:4. Add 95g of LMFP (lithium manganese iron phosphate) powder to 150g of NMP, then add 4g of GMA (glycidyl methacrylate) and stir for 12 hours. Then add 1g of NMP... SP (acetylene black) was stirred for 12 hours to obtain LMFP slurry containing prepolymer. Slurry A was prepared by mass ratio NCM(811):SP:CNT:PVDF=95:1.5:0.5:3. Slurry B was prepared by mass ratio NCM(811):LMFP:SP:CNT:PVDF=80:15:1.5:0.5:3. LMFP in slurry B is LMFP slurry containing prepolymer. Slurry A and slurry B were coated on composite aluminum foil simultaneously through a dual-module nozzle. Slurry B was coated on the side of the positive electrode near the gel membrane to form layer B, and slurry A was coated on the side of the positive electrode near the composite aluminum foil to form layer A. The thickness ratio of layer A to layer B was 1:0.5, and the viscosity ratio was 1.2:1. Both were coated on composite aluminum foil at the same time. After coating, the foil was dried at 90°C. After rolling and cutting, the positive electrode sheet was obtained. Step S2: Dissolve the first polymer and the second polymer in NMP at a ratio of 0.5:1.5 to form a prepolymer precursor solution. The first polymer is polyethylene glycol methyl ether methacrylate, and the second polymer is lithium (2-methacrylate) propyltrifluoromethanesulfonylimide (LiMTFSI). Spray the prepolymer precursor solution onto a PP membrane with a thickness of 5~10μm and dry it at a temperature of 60~80℃ to form a gel membrane. Step S3: Add graphite and Si / C (SiO2) X The following ingredients are mixed in a ratio of 80:15:1:0.5:1:1.5 (X is 0.5~1.5), SP, CNT, SBR and PAA are mixed, water is added and stirred evenly, and then dried at 90~110℃. After rolling and slitting, the negative electrode sheet is obtained. Step S4: Stack the positive electrode, gel separator, and negative electrode, and perform liquid injection formation and high-temperature and high-pressure aging. During the liquid injection formation process, add 1% initiator to the electrolyte. During the high-temperature and high-pressure aging process, maintain the temperature at 85℃ and the pressure at 2~5 MPa for 12 hours to ensure that the prepolymer precursor solution sprayed on the surface of the gel separator polymerizes with the prepolymer in the LMFP slurry in the positive electrode to form a stable three-dimensional polymer network structure, thereby preparing a high-energy battery cell. The initiator is any one of AIBN, ABVN, BPO, DCP, and TBPB. The preparation method, steps, and parameters of this embodiment are consistent with those of Example 1, except that the second polymer is lithium (2-methacrylate)propyltrifluoromethanesulfonylimide (LiMTFSI). Specifically, the prepared cell structure is as follows: Figure 3 As shown in Table 1, the cell was subjected to a needle penetration test. The cell energy density was 325Wh / kg, the capacity was 5.1Ah, the highest temperature of the hot box test was 135℃, and the highest temperature of the needle penetration test was 25.2℃. Example

[0032] This embodiment prepares a highly safe mobile power battery using the above method, and the steps include: Step S1: Set the ratio of LMFP, SP, and 3,4-epoxycyclohexyl methyl methacrylate to 95:1:4. Add 95g of LMFP (lithium manganese iron phosphate) powder to 150g of NMP, then add 4g of 3,4-epoxycyclohexyl methyl methacrylate and stir for 12 hours. Then add 1g of NMP. SP (acetylene black) was stirred for 12 hours to obtain LMFP slurry containing prepolymer. Slurry A was prepared by mass ratio NCM(811):SP:CNT:PVDF=95:1.5:0.5:3. Slurry B was prepared by mass ratio NCM(811):LMFP:SP:CNT:PVDF=80:15:1.5:0.5:3. LMFP in slurry B is LMFP slurry containing prepolymer. Slurry A and slurry B were coated on composite aluminum foil simultaneously through a dual-module nozzle. Slurry B was coated on the side of the positive electrode near the gel membrane to form layer B, and slurry A was coated on the side of the positive electrode near the composite aluminum foil to form layer A. The thickness ratio of layer A to layer B was 1:0.5, and the viscosity ratio was 1.2:1. Both were coated on composite aluminum foil at the same time. After coating, the foil was dried at 90°C. After rolling and cutting, the positive electrode sheet was obtained. Step S2: Dissolve the first polymer and the second polymer in NMP at a ratio of 0.5:1.5 to form a prepolymer precursor solution. The first polymer is polyethylene glycol methyl ether methacrylate and the second polymer is potassium N-trifluoromethanesulfonyl p-styrenesulfonylimide. Spray the prepolymer precursor solution onto a PP membrane with a thickness of 5~10μm and dry it at a temperature of 60~80℃ to form a gel membrane. Step S3: Add graphite and Si / C (SiO2) X The following ingredients are mixed in a ratio of 80:15:1:0.5:1:1.5 (X is 0.5~1.5), SP, CNT, SBR and PAA are mixed, water is added and stirred evenly, and then dried at 90~110℃. After rolling and slitting, the negative electrode sheet is obtained. Step S4: Stack the positive electrode, gel separator, and negative electrode, and perform liquid injection formation and high-temperature and high-pressure aging. During the liquid injection formation process, add 1% initiator to the electrolyte. During the high-temperature and high-pressure aging process, maintain the temperature at 85℃ and the pressure at 2~5 MPa for 12 hours to ensure that the prepolymer precursor solution sprayed on the surface of the gel separator polymerizes with the prepolymer in the LMFP slurry in the positive electrode to form a stable three-dimensional polymer network structure, thereby preparing a high-energy battery cell. The initiator is any one of AIBN, ABVN, BPO, DCP, and TBPB. The preparation method, steps, and parameters of this embodiment are consistent with those of Example 1. The only difference is that the LMFP slurry does not use GMA, but uses methyl methacrylate-3,4-epoxycyclohexyl methacrylate, and the ratio is kept at 95:1:4. The second polymer is potassium N-trifluoromethanesulfonyl p-styrenesulfonylimide. Specifically, the prepared cell structure is as follows: Figure 3 As shown in Table 1, the cell was subjected to a needle penetration test. The cell energy density was 322Wh / kg, the capacity was 5.1Ah, the highest temperature of the hot box test was 136℃, and the highest temperature of the needle penetration test was 25.4℃. Example

[0033] This embodiment prepares a highly safe mobile power battery using the above method, and the steps include: Step S1: Set the ratio of LMFP, SP, and glycidyl acrylate (GA) to 95:1:4. Add 95g of LMFP (lithium manganese iron phosphate) powder to 150g of NMP, and then add 4g of NMP. GA was stirred for 12 hours, and then 1g of SP (acetylene black) was added and stirred for 12 hours to obtain LMFP slurry containing prepolymer. Slurry A was prepared according to the mass ratio of NCM(811):SP:CNT:PVDF=95:1.5:0.5:3. Slurry B was prepared according to the mass ratio of NCM(811):LMFP:SP:CNT:PVDF=80:15:1.5:0.5:3. LMFP in slurry B is LMFP slurry containing prepolymer. Slurry A and slurry B were coated on composite aluminum foil simultaneously through a dual-module nozzle. Slurry B was coated on the side of the positive electrode close to the gel membrane to form layer B, and slurry A was coated on the side of the positive electrode close to the composite aluminum foil to form layer A. The thickness ratio of layer A to layer B was 1:0.5, and the viscosity ratio was 1.2:1. Both were coated on composite aluminum foil at the same time. After coating, the foil was dried at 90°C. After rolling and cutting, the positive electrode sheet was obtained. Step S2: Dissolve the first polymer and the second polymer in NMP at a ratio of 0.5:1.5 to form a prepolymer precursor solution. The first polymer is polyethylene glycol methyl ether methacrylate and the second polymer is potassium N-trifluoromethanesulfonyl p-styrenesulfonylimide. Spray the prepolymer precursor solution onto a PP membrane with a thickness of 5~10μm and dry it at a temperature of 60~80℃ to form a gel membrane. Step S3: Add graphite and Si / C (SiO2) X The following ingredients are mixed in a ratio of 80:15:1:0.5:1:1.5 (X is 0.5~1.5), SP, CNT, SBR and PAA are mixed, water is added and stirred evenly, and then dried at 90~110℃. After rolling and slitting, the negative electrode sheet is obtained. Step S4: Stack the positive electrode, gel separator, and negative electrode, and perform liquid injection formation and high-temperature and high-pressure aging. During the liquid injection formation process, add 1% initiator to the electrolyte. During the high-temperature and high-pressure aging process, maintain the temperature at 85℃ and the pressure at 2~5 MPa for 12 hours to ensure that the prepolymer precursor solution sprayed on the surface of the gel separator polymerizes with the prepolymer in the LMFP slurry in the positive electrode to form a stable three-dimensional polymer network structure, thereby preparing a high-energy battery cell. The initiator is any one of AIBN, ABVN, BPO, DCP, and TBPB. The preparation method, steps, and parameters of this embodiment are consistent with those of Example 4. The only difference is that the LMFP slurry does not use methyl methacrylate-3,4-epoxycyclohexyl methacrylate, but uses glycidyl acrylate (GA), and the ratio is kept at 95:1:4. The second polymer is also N-trifluoromethanesulfonyl p-styrenesulfonylimide potassium, which is consistent with Example 4. Specifically, the prepared cell structure is as follows: Figure 3 As shown in Table 1, the cell was subjected to a needle penetration test. The cell energy density was 325Wh / kg, the capacity was 5.1Ah, the highest temperature of the hot box test was 134℃, and the highest temperature of the needle penetration test was 25.5℃. Example

[0034] This embodiment prepares a highly safe mobile power battery using the above method, and the steps include: Step S1: Set the ratio of LMFP, SP, and 2-ethyl glycidyl methacrylate to 95:1:4. Add 95g of LMFP (lithium manganese iron phosphate) powder to 150g of NMP, then add 4g of 2-ethyl glycidyl methacrylate and stir for 12 hours. Then add 1g of NMP. SP (acetylene black) was stirred for 12 hours to obtain LMFP slurry containing prepolymer. Slurry A was prepared by mass ratio NCM(811):SP:CNT:PVDF=95:1.5:0.5:3. Slurry B was prepared by mass ratio NCM(811):LMFP:SP:CNT:PVDF=80:15:1.5:0.5:3. LMFP in slurry B is LMFP slurry containing prepolymer. Slurry A and slurry B were coated on composite aluminum foil simultaneously through a dual-module nozzle. Slurry B was coated on the side of the positive electrode near the gel membrane to form layer B, and slurry A was coated on the side of the positive electrode near the composite aluminum foil to form layer A. The thickness ratio of layer A to layer B was 1:0.5, and the viscosity ratio was 1.2:1. Both were coated on composite aluminum foil at the same time. After coating, the foil was dried at 90°C. After rolling and cutting, the positive electrode sheet was obtained. Step S2: Dissolve the first polymer and the second polymer in NMP at a ratio of 0.5:1.5 to form a prepolymer precursor solution. The first polymer is polyethylene glycol methyl ether methacrylate and the second polymer is potassium N-trifluoromethanesulfonyl p-styrenesulfonylimide. Spray the prepolymer precursor solution onto a PP membrane with a thickness of 5~10μm and dry it at a temperature of 60~80℃ to form a gel membrane. Step S3: Add graphite and Si / C (SiO2) X The following ingredients are mixed in a ratio of 80:15:1:0.5:1:1.5 (X is 0.5~1.5), SP, CNT, SBR and PAA are mixed, water is added and stirred evenly, and then dried at 90~110℃. After rolling and slitting, the negative electrode sheet is obtained. Step S4: Stack the positive electrode, gel separator, and negative electrode, and perform liquid injection formation and high-temperature and high-pressure aging. During the liquid injection formation process, add 1% initiator to the electrolyte. During the high-temperature and high-pressure aging process, maintain the temperature at 85℃ and the pressure at 2~5 MPa for 12 hours to ensure that the prepolymer precursor solution sprayed on the surface of the gel separator polymerizes with the prepolymer in the LMFP slurry in the positive electrode to form a stable three-dimensional polymer network structure, thereby preparing a high-energy battery cell. The initiator is any one of AIBN, ABVN, BPO, DCP, and TBPB. The preparation method, steps, and parameters of this embodiment are consistent with those of Example 4. The only difference is that the LMFP slurry does not use methyl methacrylate-3,4-epoxycyclohexyl methacrylate, but uses 2-ethyl glycidyl methacrylate, and the ratio is kept at 95:1:4. The second polymer is also N-trifluoromethanesulfonyl p-styrenesulfonylimide potassium, which is consistent with Example 5. Specifically, the prepared cell structure is as follows: Figure 3 As shown in Table 1, the cell was subjected to a needle penetration test. The cell energy density was 319Wh / kg, the capacity was 5.1Ah, the highest temperature of the hot box test was 135℃, and the highest temperature of the needle penetration test was 25.6℃. Example

[0035] This embodiment prepares a highly safe mobile power battery using the above method, and the steps include: Step S1: Set the ratio of LMFP, SP, and 3,4-epoxycyclohexyl methyl methacrylate to 95:1:4. Add 95g of LMFP (lithium manganese iron phosphate) powder to 150g of NMP, then add 4g of 3,4-epoxycyclohexyl methyl methacrylate and stir for 12h. Then add 1g of NMP. SP (acetylene black) was stirred for 12 hours to obtain LMFP slurry containing prepolymer. Slurry A was prepared by mass ratio NCM(811):SP:CNT:PVDF=95:1.5:0.5:3. Slurry B was prepared by mass ratio NCM(811):LMFP:SP:CNT:PVDF=80:15:1.5:0.5:3. LMFP in slurry B is LMFP slurry containing prepolymer. Slurry A and slurry B were coated on composite aluminum foil simultaneously through a dual-module nozzle. Slurry B was coated on the side of the positive electrode near the gel membrane to form layer B, and slurry A was coated on the side of the positive electrode near the composite aluminum foil to form layer A. The thickness ratio of layer A to layer B was 1:0.5, and the viscosity ratio was 1.2:1. Both were coated on composite aluminum foil at the same time. After coating, the foil was dried at 90°C. After rolling and cutting, the positive electrode sheet was obtained. Step S2: Dissolve the first polymer and the second polymer in NMP at a ratio of 0.5:1.5 to form a prepolymer precursor solution. The first polymer is polyethylene glycol methyl ether methacrylate and the second polymer is potassium N-trifluoromethanesulfonyl p-styrenesulfonylimide. Spray the prepolymer precursor solution onto a PP membrane with a thickness of 5~10μm and dry it at a temperature of 60~80℃ to form a gel membrane. Step S3: Add graphite and Si / C (SiO2) X The following ingredients are mixed in a ratio of 80:15:1:0.5:1:1.5 (X is 0.5~1.5), SP, CNT, SBR and PAA are mixed, water is added and stirred evenly, and then dried at 90~110℃. After rolling and slitting, the negative electrode sheet is obtained. Step S4: Stack the positive electrode, gel separator, and negative electrode, and perform liquid injection formation and high-temperature and high-pressure aging. During the liquid injection formation process, add 1% initiator to the electrolyte. During the high-temperature and high-pressure aging process, maintain the temperature at 85℃ and the pressure at 2~5 MPa for 12 hours to ensure that the prepolymer precursor solution sprayed on the surface of the gel separator polymerizes with the prepolymer in the LMFP slurry in the positive electrode to form a stable three-dimensional polymer network structure, thereby preparing a high-energy battery cell. The initiator is any one of AIBN, ABVN, BPO, DCP, and TBPB. The preparation method, steps, and parameters of this embodiment are consistent with those of Example 1. The only difference is that the LMFP slurry does not use GMA, but uses methyl methacrylate-3,4-epoxycyclohexyl methacrylate, and the ratio is kept at 95:1:4. The second polymer is potassium N-trifluoromethanesulfonyl p-styrenesulfonylimide. Specifically, the prepared cell structure is as follows: Figure 3 As shown in Table 1, the cell was subjected to a needle penetration test. The cell energy density was 320Wh / kg, the capacity was 5.1Ah, the highest temperature in the hot box test was 134℃, and the highest temperature in the needle penetration test was 27.2℃. Example

[0036] This embodiment prepares a highly safe mobile power battery using the above method, and the steps include: Step S1: Set the ratio of LMFP, SP, and GMA to 95:1:4. Add 95g of LMFP (lithium manganese iron phosphate) powder to 150g of NMP, then add 4g of GMA and stir for 12 hours. Then add 1g of NMP. SP (acetylene black) was stirred for 12 hours to obtain LMFP slurry containing prepolymer. Slurry A was prepared by mass ratio NCM(811):SP:CNT:PVDF=95:1.5:0.5:3. Slurry B was prepared by mass ratio NCM(811):LMFP:SP:CNT:PVDF=80:15:1.5:0.5:3. LMFP in slurry B is LMFP slurry containing prepolymer. Slurry A and slurry B were coated on composite aluminum foil simultaneously through a dual-module nozzle. Slurry B was coated on the side of the positive electrode near the gel membrane to form layer B, and slurry A was coated on the side of the positive electrode near the composite aluminum foil to form layer A. The thickness ratio of layer A to layer B was 1:0.5, and the viscosity ratio was 1.2:1. Both were coated on composite aluminum foil at the same time. After coating, the foil was dried at 90°C. After rolling and cutting, the positive electrode sheet was obtained. Step S2: Dissolve the first polymer and the second polymer in NMP at a ratio of 0.5:1.5 to form a prepolymer precursor solution. The first polymer is polyethylene glycol methyl ether acrylate (mPEG-acrylate), and the second polymer is potassium N-trifluoromethanesulfonyl p-styrenesulfonylimide. Spray the prepolymer precursor solution onto a PP membrane with a thickness of 5~10μm and dry it at a temperature of 60~80℃ to form a gel membrane. Step S3: Add graphite and Si / C (SiO2) X The following ingredients are mixed in a ratio of 80:15:1:0.5:1:1.5 (X is 0.5~1.5), SP, CNT, SBR and PAA are mixed, water is added and stirred evenly, and then dried at 90~110℃. After rolling and slitting, the negative electrode sheet is obtained. Step S4: Stack the positive electrode, gel separator, and negative electrode, and perform liquid injection formation and high-temperature and high-pressure aging. During the liquid injection formation process, add 1% initiator to the electrolyte. During the high-temperature and high-pressure aging process, maintain the temperature at 85℃ and the pressure at 2~5 MPa for 12 hours to ensure that the prepolymer precursor solution sprayed on the surface of the gel separator polymerizes with the prepolymer in the LMFP slurry in the positive electrode to form a stable three-dimensional polymer network structure, thereby preparing a high-energy battery cell. The initiator is any one of AIBN, ABVN, BPO, DCP, and TBPB. The preparation method, steps, and parameters of this embodiment are consistent with those of Example 1, except that the first polymer is polyethylene glycol methyl ether acrylate (mPEG-acrylate) and the second polymer is potassium N-trifluoromethanesulfonyl p-styrenesulfonylimide. Specifically, the prepared cell structure is as follows: Figure 3 As shown in Table 1, the cell was subjected to a needle penetration test. The cell energy density was 321Wh / kg, the capacity was 5.12Ah, the highest temperature in the hot box test was 134℃, and the highest temperature in the needle penetration test was 25.2℃. Example

[0037] This embodiment prepares a highly safe mobile power battery using the above method, and the steps include: Step S1: Set the ratio of LMFP, SP, and GMA to 95:1:4. Add 95g of LMFP (lithium manganese iron phosphate) powder to 150g of NMP, then add 4g of GMA and stir for 12 hours. Then add 1g of NMP. SP (acetylene black) was stirred for 12 hours to obtain LMFP slurry containing prepolymer. Slurry A was prepared by mass ratio NCM(811):SP:CNT:PVDF=95:1.5:0.5:3. Slurry B was prepared by mass ratio NCM(811):LMFP:SP:CNT:PVDF=80:15:1.5:0.5:3. LMFP in slurry B is LMFP slurry containing prepolymer. Slurry A and slurry B were coated on composite aluminum foil simultaneously through a dual-module nozzle. Slurry B was coated on the side of the positive electrode near the gel membrane to form layer B, and slurry A was coated on the side of the positive electrode near the composite aluminum foil to form layer A. The thickness ratio of layer A to layer B was 1:0.5, and the viscosity ratio was 1.2:1. Both were coated on composite aluminum foil at the same time. After coating, the foil was dried at 90°C. After rolling and cutting, the positive electrode sheet was obtained. Step S2: Dissolve the first polymer and the second polymer in NMP at a ratio of 0.5:1.5 to form a prepolymer precursor solution. The first polymer is polyethylene glycol methyl ether methacrylate and the second polymer is potassium N-trifluoromethanesulfonyl p-styrenesulfonylimide. Spray the prepolymer precursor solution onto a PP membrane with a thickness of 5~10μm and dry it at a temperature of 60~80℃ to form a gel membrane. Step S3: Add graphite and Si / C (SiO2) X The following ingredients are mixed in a ratio of 80:15:1:0.5:1:1.5 (X is 0.5~1.5), SP, CNT, SBR and PAA are mixed, water is added and stirred evenly, and then dried at 90~110℃. After rolling and slitting, the negative electrode sheet is obtained. Step S4: Stack the positive electrode, gel separator, and negative electrode, and perform liquid injection formation and high-temperature and high-pressure aging. During the liquid injection formation process, add 1% initiator to the electrolyte. During the high-temperature and high-pressure aging process, maintain the temperature at 85℃ and the pressure at 2~5 MPa for 12 hours to ensure that the prepolymer precursor solution sprayed on the surface of the gel separator polymerizes with the prepolymer in the LMFP slurry in the positive electrode to form a stable three-dimensional polymer network structure, thereby preparing a high-energy battery cell. The initiator is any one of AIBN, ABVN, BPO, DCP, and TBPB. The preparation method, steps, and parameters of this embodiment are consistent with those of Example 1, except that the first polymer is polyethylene glycol methyl ether methacrylate and the second polymer is potassium N-trifluoromethanesulfonyl p-styrenesulfonylimide. Specifically, the prepared cell structure is as follows: Figure 3 As shown in Table 1, the cell was subjected to a needle penetration test. The cell energy density was 322Wh / kg, the capacity was 5.1Ah, the highest temperature of the hot box test was 135℃, and the highest temperature of the needle penetration test was 25.5℃. Example

[0038] This embodiment prepares a highly safe mobile power battery using the above method, and the steps include: Step S1: Set the ratio of LMFP, SP, and GMA to 95:1:4. Add 95g of LMFP (lithium manganese iron phosphate) powder to 150g of NMP, then add 4g of GMA and stir for 12 hours. Then add 1g of NMP. SP (acetylene black) was stirred for 12 hours to obtain LMFP slurry containing prepolymer. Slurry A was prepared by mass ratio NCM(811):SP:CNT:PVDF=95:1.5:0.5:3. Slurry B was prepared by mass ratio NCM(811):LMFP:SP:CNT:PVDF=80:15:1.5:0.5:3. LMFP in slurry B is LMFP slurry containing prepolymer. Slurry A and slurry B were coated on composite aluminum foil simultaneously through a dual-module nozzle. Slurry B was coated on the side of the positive electrode near the gel membrane to form layer B, and slurry A was coated on the side of the positive electrode near the composite aluminum foil to form layer A. The thickness ratio of layer A to layer B was 1:0.5, and the viscosity ratio was 1.2:1. Both were coated on composite aluminum foil at the same time. After coating, the foil was dried at 90°C. After rolling and cutting, the positive electrode sheet was obtained. Step S2: Dissolve the first polymer and the second polymer in NMP at a ratio of 0.5:1.5 to form a prepolymer precursor solution. The first polymer is polyethylene glycol methacrylate and the second polymer is potassium N-trifluoromethanesulfonyl p-styrenesulfonylimide. Spray the prepolymer precursor solution onto a PP membrane with a thickness of 5~10μm and dry it at a temperature of 60~80℃ to form a gel membrane. Step S3: Add graphite and Si / C (SiO2) X The following ingredients are mixed in a ratio of 80:15:1:0.5:1:1.5 (X is 0.5~1.5), SP, CNT, SBR and PAA are mixed, water is added and stirred evenly, and then dried at 90~110℃. After rolling and slitting, the negative electrode sheet is obtained. Step S4: Stack the positive electrode, gel separator, and negative electrode, and perform liquid injection formation and high-temperature and high-pressure aging. During the liquid injection formation process, add 1% initiator to the electrolyte. During the high-temperature and high-pressure aging process, maintain the temperature at 85℃ and the pressure at 2~5 MPa for 12 hours to ensure that the prepolymer precursor solution sprayed on the surface of the gel separator polymerizes with the prepolymer in the LMFP slurry in the positive electrode to form a stable three-dimensional polymer network structure, thereby preparing a high-energy battery cell. The initiator is any one of AIBN, ABVN, BPO, DCP, and TBPB. The preparation method, steps, and parameters of this embodiment are consistent with those of Example 8, except that the first polymer is polyethylene glycol methacrylate. Specifically, the prepared cell structure is as follows: Figure 3As shown in Table 1, the cell was subjected to a needle penetration test. The cell energy density was 323Wh / kg, the capacity was 5.1Ah, the highest temperature in the hot box test was 136℃, and the highest temperature in the needle penetration test was 25.6℃.

[0039] Comparative Example 1 The comparative example uses the following method to prepare the mobile power battery, including the following steps: Step 1: Set the ratio of LMFP, SP, and GMA to 95:1:4. Add 95g of LMFP (lithium manganese iron phosphate) powder to 150g of NMP, then add 4g of GMA and stir for 12 hours. Then add 1g of NMP. SP (acetylene black) was stirred for 12 hours to obtain LMFP slurry containing prepolymer. Slurry A was prepared by mass ratio NCM(811):SP:CNT:PVDF=95:1.5:0.5:3. Slurry B was prepared by mass ratio NCM(811):LMFP:SP:CNT:PVDF=80:15:1.5:0.5:3. LMFP in slurry B is LMFP slurry containing prepolymer. Slurry A and slurry B were coated on composite aluminum foil simultaneously through a dual-module nozzle. Slurry B was coated on the side of the positive electrode near the gel membrane to form layer B, and slurry A was coated on the side of the positive electrode near the composite aluminum foil to form layer A. The thickness ratio of layer A to layer B was 1:0.5, and the viscosity ratio was 1.2:1. Both were coated on composite aluminum foil at the same time. After coating, the foil was dried at 90°C. After rolling and cutting, the positive electrode sheet was obtained. Step 2: Use a PP membrane with a thickness of 10μm; Step 3: Add graphite and Si / C (SiO2) X The following ingredients are mixed in a ratio of 80:15:1:0.5:1:1.5 (X is 0.5~1.5), SP, CNT, SBR and PAA are mixed, water is added and stirred evenly, and then dried at 90~110℃. After rolling and slitting, the negative electrode sheet is obtained. Step 4: Stack the positive electrode, separator, and negative electrode, and perform liquid injection formation and high-temperature and high-pressure aging. During the liquid injection formation process, add 1% initiator to the electrolyte. During the high-temperature and high-pressure aging process, maintain the temperature at 85℃ and the pressure at 2~5Mpa for 12h. The initiator is any one of AIBN, ABVN, BPO, DCP, and TBPB, thereby preparing the battery cell. The comparative example is consistent with the preparation method, steps and parameters of Example 1. The only difference is that the prepolymer precursor solution formed by the first polymer and the second polymer in proportion is not used, the prepolymer precursor solution is not sprayed on the PP membrane, the drying treatment is not carried out at a temperature of 60~80°C, and a gel membrane is not formed. Only an untreated PP membrane is used. Specifically, the prepared battery cells were subjected to a needle penetration test. The relevant data of the battery cells obtained from the test are shown in Table 1. The battery cell energy density is 320Wh / kg, the battery cell capacity is 5.1Ah, the highest temperature of the hot box test is 134℃, and the highest temperature of the needle penetration test is 680.4℃.

[0040] The needle penetration tests in the above embodiments and comparative examples were all conducted in a glove box under the same physical conditions: moisture content ≤0.1 PPM and oxygen content ≤0.1 PPM. The specific performance tests of the above embodiments and comparative examples are shown in Table 1. Cell energy density refers to the electrical energy that a unit mass of cell can store. The higher the value, the stronger the battery life of the same weight of cell. Cell capacity refers to the rated capacity of the cell, which represents the total amount of charge that the cell can release under specified discharge conditions, reflecting the total amount of energy stored in the cell. The hot box test simulates the cell's tolerance to high temperature environments. The highest temperature of the hot box test is the highest temperature reached by the cell during the hot box test, reflecting the thermal stability of the cell. The needle penetration test is used to simulate the extreme situation where the cell is punctured by a sharp object and an internal short circuit occurs. The highest temperature of the needle penetration test is the highest internal temperature reached by the cell after being punctured by a needle. Table 1 - Comparison of performance data of batteries prepared in different embodiments and comparative examples Example 1 322 5.0 134 25.5 Example 2 323 5.1 135 26.5 Example 3 325 5.1 135 25.2 Example 4 322 5.1 136 25.4 Example 5 325 5.1 134 25.5 Example 6 319 5.1 135 25.6 Example 7 320 5.1 134 27.2 Example 8 321 5.12 134 25.2 Example 9 322 5.1 135 25.5 Example 10 323 5.1 136 25.6 Comparative Example 1 320 5.1 134 680.4 Table 1 shows that the tested cell energy density can reach 280~340Wh / kg, and the measured cell capacity is stable in the range of 5.0~5.12Ah. While ensuring high safety, it retains the core performance of high-energy-density lithium-ion batteries, meeting the needs of mobile power supplies for battery life and miniaturization. The highest temperature of the cell hot box test is controlled at 134~136℃, which is far below the thermal runaway critical temperature. It can still maintain structural and performance stability in high-temperature environments, effectively reducing safety risks during high-temperature use and storage. The highest temperature of the needle penetration test is 25.2~27.2℃, which is a qualitative leap compared to the highest needle penetration temperature of 680.4℃ of traditional cells. The cell can pass the needle penetration test when fully charged, fundamentally solving the problem of thermal runaway caused by internal short circuits in high-energy-density cells during needle penetration. A multi-dimensional performance data comparison was conducted between Examples 1-10 and Comparative Example 1. Comparative Example 1, which did not use a gel separator, experienced severe thermal runaway during the needle penetration test. In contrast, the battery cells of Examples 1-10 maintained excellent performance across the board, and the needle penetration safety was significantly improved. This directly verifies the effectiveness of the gel separator preparation, positive electrode double-layer coating, and in-situ polymerization scheme of the present invention. Furthermore, according to Examples 1-10, it can be seen that after the raw materials are replaced (such as prepolymers or lithium salt derivatives), the energy density, capacity, and thermal box test performance of the battery cells remain basically stable, and the highest temperature of the needle penetration test is controlled below 30°C. This proves that the technical solution of the present invention has good adaptability to the fine-tuning of relevant raw material derivatives.

[0041] In summary, this invention improves safety by introducing polymers into conventional battery cell structures. It involves spraying a lithium salt polymer that conducts lithium ions and a long-chain polymer that increases the thermal stability and flexibility of the separator onto the separator surface. During aging, these polymers are polymerized with prepolymers added to the LMFP slurry, forming a safe and stable three-dimensional network structure on the positive electrode side. Experimental data shows that the polymers can effectively prevent thermal runaway caused by short circuits within the positive and negative electrodes during the needle penetration test, enabling high-energy-density battery cells to pass the needle penetration test fully charged and improving the needle penetration pass rate of high-energy-density battery cells.

[0042] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing a high-safety mobile power bank battery, characterized in that, Specifically, the following steps are included: Step S1: Prepare the positive electrode sheet; Step S2: Dissolve the first polymer and the second polymer in NMP in a certain proportion to form a prepolymer precursor solution. Spray the prepolymer precursor solution onto the PP membrane and dry it at a temperature of 60~80°C to form a gel membrane. Step S3: Mix graphite, Si / C, SP, CNT, SBR and PAA in proportion, add water and stir evenly, then dry at 90~110℃, and obtain negative electrode sheet by rolling and slitting. Step S4: Stack the positive electrode, gel separator, and negative electrode, and perform liquid injection formation and high-temperature and high-pressure aging to prepare a high-energy battery cell; Specifically, step S1 includes: Step S11: Add LMFP powder to NMP, then add GMA and stir for 12 hours, then add SP and stir for 12 hours to obtain LMFP slurry containing prepolymer; Step S12: Prepare slurry A by mass ratio NCM:SP:CNT:PVDF=95:1.5:0.5:3, and prepare slurry B by mass ratio NCM:LMFP:SP:CNT:PVDF=80:15:1.5:0.5:3, wherein LMFP in slurry B is LMFP slurry containing prepolymer; Step S13: Apply slurry A and slurry B to the composite aluminum foil simultaneously using a dual-module nozzle. Slurry B is applied to the side of the positive electrode near the gel membrane to form layer B, and slurry A is applied to the side of the positive electrode near the composite aluminum foil to form layer A. After the coating operation, the electrode is dried at 90°C and then rolled and slit to obtain the positive electrode sheet.

2. The method for preparing a high-safety mobile power bank battery according to claim 1, characterized in that, Step S4 specifically includes: adding 1% of an initiator to the electrolyte during the liquid injection formation process; maintaining the temperature at 85°C and the pressure at 2-5 MPa during the high-temperature and high-pressure aging process to ensure that the prepolymer precursor solution sprayed on the surface of the gel separator polymerizes with the prepolymer in the LMFP slurry in the positive electrode to form a stable three-dimensional polymer network structure.

3. The method for preparing a high-safety mobile power bank battery according to claim 1, characterized in that, In step S11, the LMFP slurry is prepared at a mass ratio of LMFP:SP:GMA = 95:1:

4.

4. The method for preparing a high-safety mobile power bank battery according to claim 1, characterized in that, In step S11, the amount of NMP added is 150g of NMP for every 95g of LMFP powder.

5. The method for preparing a high-safety mobile power bank battery according to claim 1, characterized in that, In step S13, the coating thickness ratio of layer A to layer B is 1:0.5, and the viscosity ratio is 1.2:

1.

6. The method for preparing a high-safety mobile power bank battery according to claim 1, characterized in that, The positive electrode active material of the positive electrode sheet in step S13 is not limited to NCM, but also includes any one of LCO and LFP.

7. The method for preparing a high-safety mobile power bank battery according to claim 1, characterized in that, In step S2, the ratio of the first polymer to the second polymer is set to 0.5:1.

5. The first polymer is polyethylene glycol methyl ether methacrylate, and the second polymer is lithium N-trifluoromethanesulfonyl p-styrenesulfonylimide and its derivatives.

8. The method for preparing a high-safety mobile power bank battery according to claim 1, characterized in that, The thickness of the PP diaphragm in step S2 is 5~10μm.

9. The method for preparing a high-safety mobile power bank battery according to claim 1, characterized in that, In step S3, the ratio of graphite, Si / C, SP, CNT, SBR and PAA is set to 80:15:1:0.5:1:1.

5.

10. The method for preparing a high-safety mobile power bank battery according to claim 2, characterized in that, The initiator is any one of AIBN, ABVN, BPO, DCP, and TBPB.

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