Preparation method of rate type square lithium ion battery

Abstract

The invention discloses a preparation method of a rate type square lithium ion battery. The preparation method comprises the following steps: step 1, forming a glue solution; step 2, quickly stirring and dispersing into uniform positive electrode slurry under a vacuum condition; step 3; step 4, preparing a glue solution; 5, stirring and dispersing in vacuum to form stable negative electrode slurry; step 6, preparing a negative plate; step 7, obtaining a naked battery cell; step 9; step 10, welding the positive pole lug of the naked battery cell with the positive pole cover plate; step 11; and step 12, preparing the rate type square lithium ion battery. Small-particle-size positive electrode lithium iron phosphate and single-particle negative electrode graphite are selected to prepare positive and negative electrode plates, and the positive and negative electrode plates and a diaphragm are subjected to a Z-shaped lamination process to prepare the square aluminum shell lithium ion battery; the battery manufacturing method is simple, the impedance is small, 4C high-rate charging and 6C high-rate discharging are supported, 80% SOC can be charged in 12 min, and the battery can be applied to special vehicles, UPSs and scenes needing rapid power storage and standby power.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a method for preparing a high-rate square lithium-ion battery. Background Technology

[0002] In recent years, the driving range and power performance of electric vehicles have become comparable to those of traditional gasoline vehicles. However, compared to refueling traditional gasoline vehicles, a prominent issue with electric vehicles is the long charging time. This "charging anxiety" of electric vehicles places higher demands on the charging speed of lithium-ion batteries. According to the definition proposed by the Advanced Battery Consortium in the United States, fast charging means charging the battery to 80% capacity within 15 minutes, meaning the battery can operate stably and continuously at a high rate of 4C. Therefore, improving the fast charging capability and power performance of lithium-ion batteries, while ensuring high safety, low cost, and long lifespan, is of particular significance for promoting the development of industries such as electric vehicles, UPS, and energy storage. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a high-rate square lithium-ion battery to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a high-rate square lithium-ion battery, comprising the following steps:

[0005] Step 1: Mix polyvinylidene fluoride and N-methylpyrrolidone in a certain mass ratio under vacuum and stir until homogeneous to form a glue solution;

[0006] Step 2: Mix the lithium iron phosphate cathode material, conductive carbon black, and graphene composite conductive slurry with the adhesive solution prepared in Step 1 at a certain mass ratio, and quickly stir and disperse them under vacuum conditions to form a uniform cathode slurry.

[0007] Step 3: The prepared slurry is uniformly coated onto the positive electrode current collector coated with carbon aluminum foil at a certain density, and then rolled, die-cut and baked to obtain the positive electrode sheet;

[0008] Step 4: Mix sodium carboxymethyl cellulose and deionized water in a certain mass ratio under vacuum to obtain a gel solution;

[0009] Step 5: Mix the graphite negative electrode active material with conductive carbon black, styrene-acrylic emulsion, and functional polymer in a certain mass ratio with the adhesive solution prepared in Step 4, and stir and disperse under vacuum to form a stable negative electrode slurry.

[0010] Step 6: Apply the prepared negative electrode slurry to the negative electrode current collector copper foil at a certain density, and then roll, die-cut and bake to obtain the negative electrode sheet;

[0011] Step 7: Provide a lithium-ion battery separator;

[0012] Step 8: Obtain the bare cell by using a Z-shaped stacking process in the order of positive electrode, separator, negative electrode, and separator;

[0013] Step 9: Provide a square lithium-ion battery aluminum casing, positive electrode cover plate, negative electrode cover plate, positive electrode separator ring, side support plate, and Mylar film;

[0014] Step 10: Weld the negative electrode tab of the bare cell to the negative electrode cover plate, and after being wrapped and fixed by the Mylar film, side support plate and positive electrode insulating ring, place it in the aluminum shell of the square lithium-ion battery. Then weld the positive electrode tab of the bare cell to the positive electrode cover plate.

[0015] Step 11: Seal and weld the positive electrode cover plate and the negative electrode cover plate to the square lithium-ion battery aluminum shell to obtain a semi-finished battery cell;

[0016] Step 12: The semi-finished cells are baked, injected with electrolyte, formed, injected with electrolyte again, sealed and tested for capacity to obtain a high-rate square lithium-ion battery.

[0017] In step 1, the mass ratio of polyvinylidene fluoride and N-methylpyrrolidone is 100:7.5.

[0018] In step 2, the primary particle size of the lithium iron phosphate cathode material is 100-200 nm, the D50 is 1-2 μm, and the specific surface area is 10-14 m². 2 / g, with a capacity of 140-150mAh / g;

[0019] In the positive electrode slurry, the mass ratio of lithium iron phosphate positive electrode material, conductive carbon black, graphene composite conductive slurry, and polyvinylidene fluoride is 93.5-97.5:1.3-1.7:0.9-1.1:1.5-2.5.

[0020] The vacuum degree during stirring is -60 to -80 kPa.

[0021] In step 3, the density of the positive electrode slurry coated on the carbon-coated aluminum foil of the positive electrode current collector is 200–340 mg / m³. 2 The coating speed is 1-20 m / min;

[0022] The baking temperature is 65–200℃;

[0023] The rolling pressure during rolling is 20-40T, the sheet length is 200mm-300mm, the sheet width is 80-150mm, the tab length is 10-40mm, and the tab width is 20-50mm.

[0024] In step 5, the graphite anode active material is a single-particle solid-phase coated graphite with a D50 of 5-9 μm and a specific surface area of ​​1.4-2.2 m². 2 / g, with a capacity of 330-340mAh / g;

[0025] In the negative electrode slurry, the mass ratio of graphite negative electrode active material, conductive carbon black, sodium carboxymethyl cellulose, styrene-acrylic emulsion, and functional polymer is 92-95:1.6-2.4:1.3-1.7:2-3:0.1-0.3.

[0026] The vacuum degree during stirring is -60 to -80 kPa.

[0027] In step 6, the density of the negative electrode slurry coated on the negative electrode current collector copper foil is 120-150 mg / m³. 2 The coating speed is 1-20 m / min;

[0028] The baking temperature is 65-100℃;

[0029] The rolling pressure during rolling is 20-40T, the sheet length is 200mm-300mm, the sheet width is 80-150mm, the tab length is 10-40mm, and the tab width is 20-50mm.

[0030] In step 7, the diaphragm is either a dry diaphragm or a wet diaphragm, with a thickness of 7-25 μm, a porosity of 30%-50%, and a width of 210-310 mm.

[0031] In step 8, the Z-shaped stacking process involves the separator moving along a Z-shaped path and being placed between the positive and negative electrode plates. Stacking stops when the required number of electrodes is reached.

[0032] In step 10, the welding method between the positive electrode tab and the positive electrode cover plate, and between the negative electrode tab and the negative electrode cover plate, is one of laser welding, ultrasonic welding, or friction welding.

[0033] In step 12, the electrolyte solvent for the injection is a mixture of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, and dimethyl carbonate in a mass ratio of 30%:5%:55%:10%.

[0034] The electrolyte contains 10%-15% lithium salt (LiPF6) and 0.2%-0.8% LiFSI.

[0035] The process involves high-temperature negative pressure formation at 45°C.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] This invention utilizes small-particle lithium iron phosphate as the positive electrode and single-particle graphite as the negative electrode to form positive and negative electrode sheets, which are then stacked with a separator using a "Z" shaped stacking process to produce a square aluminum-cased lithium-ion battery. The battery is simple to manufacture, has low impedance, supports 4C high-rate charging and 6C high-rate discharging, and can be charged to 80% SOC in 12 minutes. It can be applied to special vehicles, UPS, and other scenarios requiring rapid energy storage and backup power. Attached Figure Description

[0038] Figure 1 This is a high-rate charging curve of the battery of the present invention;

[0039] Figure 2 This is a high-rate discharge curve of the battery of the present invention;

[0040] Figure 3 This is a graph showing the change in high-power performance of the battery of the present invention with the number of cycles. Detailed Implementation

[0041] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0042] Example 1

[0043] A method for preparing a high-rate prismatic lithium-ion battery includes the following steps:

[0044] Step 1: Mix polyvinylidene fluoride and N-methylpyrrolidone at a mass ratio of 100%:7.5 under vacuum at -60 to -80 kPa to form a gel solution.

[0045] Step 2: Mix the lithium iron phosphate cathode material, conductive carbon black, and graphene composite conductive slurry with the adhesive solution prepared in Step 1 at a mass ratio of 95.5:1.5:1, and rapidly stir and disperse them under vacuum to form a uniform cathode slurry.

[0046] Step 3: Mix the prepared positive electrode slurry with a density of 200-340 mg / m³. 2 The carbon-coated aluminum foil is uniformly coated onto the positive electrode current collector. The thickness of the carbon-coated aluminum foil is 13μm, and the coating speed is 1~20m / min. The positive electrode sheet is obtained by rolling (rolling pressure is 20~40T), die cutting, and baking (oven temperature is 65~100℃). The sheet length is 200mm~300mm, the sheet width is 80~150mm, the tab length is 10~40mm, and the tab width is 20~50mm.

[0047] Step 4: Mix sodium carboxymethyl cellulose and deionized water at a mass ratio of 1.6:100 under vacuum of -60 to -80 kPa to obtain a gel solution;

[0048] Step 5: Mix the graphite negative electrode active material with conductive carbon black, styrene-acrylic emulsion (SBR), and functional polymer (SFC) in a mass ratio of 93.8:2:2.5:0.2 with the slurry prepared in Step 4 and stir and disperse under vacuum to form a stable negative electrode slurry;

[0049] Step 6: Mix the prepared negative electrode slurry with a density of 120-150 mg / m³. 2 The coating is applied to the copper foil of the negative electrode current collector. The copper foil thickness is 8μm, and the coating speed is 1-20m / min. The negative electrode sheet is obtained by rolling (rolling pressure is 20-40T), die cutting, and baking (oven temperature is 65-100℃). The sheet length is 200mm-300mm, the sheet width is 80-150mm, the tab length is 10-40mm, and the tab width is 20-50mm.

[0050] Step 7: Provide a lithium-ion battery separator. The separator is a 25μm dry-process separator with a porosity of 42% and a width of 298mm.

[0051] Step 8: The materials are stacked in the order of positive electrode, separator, negative electrode, and separator to obtain bare cells using a "Z" shaped stacking process;

[0052] Step 9: Provide a square lithium-ion battery aluminum casing, positive and negative electrode covers, positive electrode separator ring, side support plate, and Mylar film;

[0053] Step 10: The bare cell negative electrode tab and negative electrode cover plate are laser welded together. After being wrapped and fixed by Mylar film, side support plate and positive electrode insulating ring, it is placed in the square lithium-ion battery aluminum shell. Then the positive electrode tab and positive electrode cover plate are laser welded together.

[0054] Step 11: Seal and weld the positive electrode cover plate and negative electrode cover plate to the square lithium-ion battery aluminum shell to obtain a semi-finished battery cell;

[0055] Step 12: The semi-finished battery cells are baked, injected with electrolyte (the electrolyte solvent is ethylene carbonate, propylene carbonate, ethyl methyl carbonate and dimethyl carbonate mixed in a mass ratio of 30%:5%:55%:10%, the lithium salt LiPF6 content in the electrolyte is 10%~15%, and the LiFSI content is 0.2%~0.8%), formed, injected with electrolyte a second time, sealed, and tested for capacity to obtain a rate-capacity square lithium-ion battery.

[0056] Example 2

[0057] A method for preparing a high-rate prismatic lithium-ion battery includes the following steps:

[0058] Step 1: Mix polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) at a mass ratio of 100:7.5 under vacuum of -60 to -80 kPa to form a slurry.

[0059] Step 2: Mix the lithium iron phosphate cathode material, conductive carbon black, and graphene composite conductive slurry with the adhesive solution prepared in Step 1 at a mass ratio of 95.5:1.5:1, and rapidly stir and disperse them under vacuum to form a uniform cathode slurry.

[0060] Step 3: Mix the prepared positive electrode slurry with a density of 200-340 mg / m³. 2 The carbon-coated aluminum foil is uniformly coated onto the positive electrode current collector. The thickness of the carbon-coated aluminum foil is 15μm, and the coating speed is 1-20m / min. The positive electrode sheet is obtained by rolling (rolling pressure of 20-40T), die cutting, and baking (oven temperature of 65-100℃). The sheet length is 200mm-300mm, the sheet width is 80-150mm, the tab length is 10-40mm, and the tab width is 20-50mm.

[0061] Step 4: Mix sodium carboxymethyl cellulose (CMC) and deionized water at a mass ratio of 1.6:100 under vacuum of -60 to -80 kPa to obtain a gel solution;

[0062] Step 5: Mix the graphite negative electrode active material with conductive carbon black, styrene-acrylic emulsion (SBR), and functional polymer (SFC) in a mass ratio of 93.8:2:2.5:0.2 with the slurry prepared in Step 4 and stir and disperse under vacuum to form a stable negative electrode slurry;

[0063] Step 6: Mix the prepared negative electrode slurry with a density of 120-150 mg / m³. 2 The coating is applied to the copper foil of the negative electrode current collector, with a copper foil thickness of 8μm and a coating speed of 1–20 m / min. The negative electrode sheet is then produced by rolling (rolling pressure 20–40T), die-cutting, and baking (oven temperature 65–100℃). The sheet length is 200–300 mm, the sheet width is 80–150 mm, the tab length is 10–40 mm, and the tab width is 20–50 mm.

[0064] Step 7: Provide a lithium-ion battery separator. The separator is a 16μm wet-process separator with a porosity of 43% and a width of 298mm.

[0065] Step 8: The materials are stacked in the order of positive electrode, separator, negative electrode, and separator to obtain bare cells using a "Z" shaped stacking process;

[0066] Step 9: Provide a square lithium-ion battery aluminum casing, positive and negative electrode covers, positive electrode separator ring, side support plate, and Mylar film;

[0067] Step 10: The bare cell negative electrode tab and negative electrode cover plate are laser welded together. After being wrapped and fixed by Mylar film, side support plate and positive electrode insulating ring, it is placed in the square lithium-ion battery aluminum shell. Then the positive electrode tab and positive electrode cover plate are laser welded together.

[0068] Step 11: Seal and weld the positive electrode cover plate and the negative electrode cover plate to the square lithium-ion battery aluminum shell to obtain a semi-finished battery cell;

[0069] Step 12: The semi-finished battery cells are baked, injected with electrolyte (the electrolyte solvent is ethylene carbonate, propylene carbonate, ethyl methyl carbonate and dimethyl carbonate mixed in a mass ratio of 30%:5%:55%:10%, the lithium salt LiPF6 content in the electrolyte is 10%~15%, and the LiFSI content is 0.2%~0.8%), formed, injected with electrolyte a second time, sealed, and tested for capacity to obtain a rate-capacity square lithium-ion battery.

[0070] Example 3

[0071] A method for preparing a high-rate prismatic lithium-ion battery includes the following steps:

[0072] Step 1: Mix polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) at a mass ratio of 100:7.5 under vacuum of -60 to -80 kPa to form a slurry.

[0073] Step 2: Mix the lithium iron phosphate cathode material, conductive carbon black, and graphene composite conductive slurry with the adhesive solution prepared in Step 1 at a mass ratio of 95.5:1.5:1, and rapidly stir and disperse them under vacuum to form a uniform cathode slurry.

[0074] Step 3: Mix the prepared positive electrode slurry with a density of 200-340 mg / m³. 2 The carbon-coated aluminum foil is uniformly coated onto the positive electrode current collector. The thickness of the carbon-coated aluminum foil is 15μm, and the coating speed is 1-20m / min. The positive electrode sheet is obtained by rolling (rolling pressure of 20-40T), die cutting, and baking (oven temperature of 65-100℃). The sheet length is 200mm-300mm, the sheet width is 80-150mm, the tab length is 10-40mm, and the tab width is 20-50mm.

[0075] Step 4: Mix sodium carboxymethyl cellulose (CMC) and deionized water at a mass ratio of 1.6:100 under vacuum of -60 to -80 kPa to obtain a gel solution;

[0076] Step 5: Mix the graphite negative electrode active material with conductive carbon black, styrene-acrylic emulsion (SBR), and functional polymer (SFC) in a mass ratio of 93.8:2:2.5:0.2 with the slurry prepared in Step 4 and stir and disperse under vacuum to form a stable negative electrode slurry;

[0077] Step 6: Mix the prepared negative electrode slurry with a density of 120-150 mg / m³. 2 The coating is applied to the copper foil of the negative electrode current collector, with a copper foil thickness of 8μm and a coating speed of 1–20 m / min. The negative electrode sheet is then produced by rolling (rolling pressure 20–40T), die-cutting, and baking (oven temperature 65–100℃). The sheet length is 200–300 mm, the sheet width is 80–150 mm, the tab length is 10–40 mm, and the tab width is 20–50 mm.

[0078] Step 7: Provide a lithium-ion battery separator. The separator is a 12μm wet-process separator with a porosity of 46% and a width of 298mm.

[0079] Step 8: The materials are stacked in the order of positive electrode, separator, negative electrode, and separator to obtain bare cells using a "Z" shaped stacking process;

[0080] Step 9: Provide a square lithium-ion battery aluminum casing, positive and negative electrode covers, positive electrode separator ring, side support plate, and Mylar film;

[0081] Step 10: The bare cell negative electrode tab and negative electrode cover plate are laser welded together. After being wrapped and fixed by Mylar film, side support plate and positive electrode insulating ring, it is placed in the square lithium-ion battery aluminum shell. Then the positive electrode tab and positive electrode cover plate are laser welded together.

[0082] Step 11: Seal and weld the positive electrode cover plate and the negative electrode cover plate to the square lithium-ion battery aluminum shell to obtain a semi-finished battery cell;

[0083] Step 12: The semi-finished battery cells are baked, injected with electrolyte (the electrolyte solvent is ethylene carbonate, propylene carbonate, ethyl methyl carbonate and dimethyl carbonate mixed in a mass ratio of 30%:5%:55%:10%, the lithium salt LiPF6 content in the electrolyte is 10%~15%, and the LiFSI content is 0.2%~0.8%), formed, injected with electrolyte a second time, sealed, and tested for capacity to obtain a rate-capacity square lithium-ion battery.

[0084] Experimental Example

[0085] The rate-controlled prismatic lithium-ion batteries prepared in Examples 1, 2, and 3 were subjected to battery property testing. The test results are shown in Table 1 below. High-rate charging tests, high-rate discharging tests, high-power performance tests, and cycle performance tests were also conducted on the rate-controlled prismatic lithium-ion batteries prepared in Examples 1, 2, and 3. Specific test results are provided in the appendix to the instruction manual. Figure 1-3 As shown;

[0086] Table 1 Battery property test data

[0087]

[0088] From Table 1 and Figure 1 , 2 As can be seen from point 3, the high-rate square lithium-ion battery prepared by the method of this invention can meet the requirements of high-rate charging and discharging while ensuring cycle life. Therefore, this invention uses small-particle-size lithium iron phosphate positive electrode and single-particle graphite negative electrode to make positive and negative electrode sheets, and then uses a "Z"-shaped stacking process with a separator to produce a square aluminum-cased lithium-ion battery. The battery manufacturing method is simple, has low impedance, and supports 4C high-rate charging and 6C high-rate discharging. It can charge to 80% SOC in 12 minutes and can be applied to special vehicles, UPS, and other scenarios requiring rapid energy storage and backup power.

[0089] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a high-rate prismatic lithium-ion battery, characterized in that, Includes the following steps: Step 1: Mix polyvinylidene fluoride and N-methylpyrrolidone in a certain mass ratio under vacuum and stir until homogeneous to form a glue solution; Step 2: Mix the lithium iron phosphate cathode material, conductive carbon black, and graphene composite conductive slurry with the adhesive solution prepared in Step 1 at a certain mass ratio, and quickly stir and disperse them under vacuum conditions to form a uniform cathode slurry. Step 3: The prepared slurry is evenly coated onto the positive electrode current collector coated with carbon aluminum foil at a certain density, and then rolled, die-cut and baked to obtain the positive electrode sheet; Step 4: Mix sodium carboxymethyl cellulose and deionized water in a certain mass ratio under vacuum to obtain a gel solution; Step 5: Mix the graphite negative electrode active material with conductive carbon black, styrene-acrylic emulsion, and functional polymer in a certain mass ratio with the adhesive solution prepared in Step 4, and stir and disperse under vacuum to form a stable negative electrode slurry. Step 6: Apply the prepared negative electrode slurry to the negative electrode current collector copper foil at a certain density, and then roll, die-cut and bake to obtain the negative electrode sheet; Step 7: Provide a lithium-ion battery separator; Step 8: Obtain the bare cell by using a Z-shaped stacking process in the order of positive electrode, separator, negative electrode, and separator; Step 9: Provide a square lithium-ion battery aluminum casing, positive electrode cover plate, negative electrode cover plate, positive electrode separator ring, side support plate, and Mylar film; Step 10: Weld the negative electrode tab of the bare cell to the negative electrode cover plate, and after being wrapped and fixed by the Mylar film, side support plate and positive electrode insulating ring, place it in the aluminum shell of the square lithium-ion battery. Then weld the positive electrode tab of the bare cell to the positive electrode cover plate. Step 11: Seal and weld the positive electrode cover plate and the negative electrode cover plate to the square lithium-ion battery aluminum shell to obtain a semi-finished battery cell; Step 12: The semi-finished cells are baked, injected with electrolyte, formed, injected with electrolyte again, sealed and tested for capacity to obtain a high-rate square lithium-ion battery.

2. The method for preparing a high-rate prismatic lithium-ion battery according to claim 1, characterized in that: In step 1, the mass ratio of polyvinylidene fluoride and N-methylpyrrolidone is 100:7.

5.

3. The method for preparing a high-rate prismatic lithium-ion battery according to claim 1, characterized in that: In step 2, the primary particle size of the lithium iron phosphate cathode material is 100-200 nm, the D50 is 1-2 μm, and the specific surface area is 10-14 m². 2 / g, with a capacity of 140-150mAh / g; In the positive electrode slurry, the mass ratio of lithium iron phosphate positive electrode material, conductive carbon black, graphene composite conductive slurry, and polyvinylidene fluoride is 93.5-97.5:1.3-1.7:0.9-1.1:1.5-2.

5. The vacuum degree during stirring is -60 to -80 kPa.

4. The method for preparing a high-rate prismatic lithium-ion battery according to claim 1, characterized in that: In step 3, the density of the positive electrode slurry coated on the carbon-coated aluminum foil of the positive electrode current collector is 200–340 mg / m³. 2 The coating speed is 1-20 m / min; The baking temperature is 65–200℃; The rolling pressure during rolling is 20-40T, the sheet length is 200mm-300mm, the sheet width is 80-150mm, the tab length is 10-40mm, and the tab width is 20-50mm.

5. The method for preparing a high-rate prismatic lithium-ion battery according to claim 1, characterized in that: In step 5, the graphite anode active material is single-particle solid-phase coated graphite with a D50 of 5-9 μm and a specific surface area of ​​1.4-2.2 m². 2 / g, with a capacity of 330-340mAh / g; In the negative electrode slurry, the mass ratio of graphite negative electrode active material, conductive carbon black, sodium carboxymethyl cellulose, styrene-acrylic emulsion, and functional polymer is 92-95: 1.6-2.4：1.3-1.7：2-3：0.1-0.3； The vacuum degree during stirring is -60 to -80 kPa.

6. The method for preparing a high-rate prismatic lithium-ion battery according to claim 1, characterized in that: In step 6, the density of the negative electrode slurry coated on the negative electrode current collector copper foil is 120-150 mg / m³. 2 The coating speed is 1-20 m / min; The baking temperature is 65-100℃; The rolling pressure during rolling is 20-40T, the sheet length is 200mm-300mm, the sheet width is 80-150mm, the tab length is 10-40mm, and the tab width is 20-50mm.

7. The method for preparing a high-rate prismatic lithium-ion battery according to claim 1, characterized in that: In step 7, the diaphragm is either a dry diaphragm or a wet diaphragm, with a thickness of 7-25 μm, a porosity of 30%-50%, and a width of 210-310 mm.

8. The method for preparing a high-rate prismatic lithium-ion battery according to claim 1, characterized in that: In step 8, the Z-shaped stacking process involves the separator moving along a Z-shaped path and being placed between the positive and negative electrode plates. Stacking stops when the required number of electrodes is reached.

9. The method for preparing a high-rate prismatic lithium-ion battery according to claim 1, characterized in that: In step 10, the welding method between the positive electrode tab and the positive electrode cover plate, and between the negative electrode tab and the negative electrode cover plate, is one of laser welding, ultrasonic welding, or friction welding.

10. The method for preparing a high-rate prismatic lithium-ion battery according to claim 1, characterized in that: In step 12, the electrolyte solvent for the injection is a mixture of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, and dimethyl carbonate in a mass ratio of 30%:5%:55%:10%. The electrolyte contains 10%-15% lithium salt (LiPF6) and 0.2%-0.8% LiFSI. The process involves high-temperature negative pressure formation at 45°C.

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