A preparation method and application of a bottom-coated current collector for improving cycle life of lithium batteries

Abstract

This invention discloses a method for preparing and applying a bottom-coated current collector to improve the cycle life of lithium batteries, relating to the field of lithium battery technology. This application improves the cycle performance of lithium batteries by applying a bottom-coating slurry on aluminum foil, increasing the capacity retention rate of the battery after long cycles. The stable olivine structure and high-voltage platform of LMFP in the bottom-coating slurry can share some of the voltage stress and reduce the phase transition degree of NCM. Simultaneously, LMFP has better thermal stability than NCM materials and is difficult to decompose at high temperatures, thus protecting the structural stability of NCM materials at high temperatures. The high mechanical strength of AlOOH in the bottom-coating slurry, with a small amount added, can suppress material shedding caused by the volume expansion of NCM materials after long cycles. Furthermore, boehmite has excellent thermal stability, preventing heat propagation inside the battery, thereby improving the battery's cycle performance.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, specifically a method for preparing and applying a base-coated current collector to improve the cycle life of lithium batteries. Background Technology

[0002] In today's new energy market, ternary cathode materials are considered to be highly promising active materials for lithium batteries due to their high capacity. Therefore, ternary materials are widely used in power batteries and high-end energy fields.

[0003] Currently, the ternary NCM materials on the market are mainly 622 and 523. This is primarily because NCM811 has a high nickel content, making its structure less stable during long-term charge-discharge cycles and resulting in decreased cycle performance. Therefore, improving the cycle performance of high-nickel ternary materials has become a top priority. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing and applying a base coat current collector to improve the cycle life of lithium batteries, thereby solving the problems raised in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a base coating current collector to improve the cycle life of lithium batteries, comprising the following steps: Step 1: Mix the binder and solvent, disperse them evenly, and then add LMFP (lithium manganese iron phosphate), PVP (polyvinylpyrrolidone), conductive agent and AlOOH (boehmite) that have been pretreated by ball milling in sequence. Stir evenly to obtain the primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil, and dry it to obtain the primer current collector.

[0006] Furthermore, in step 1, the process conditions for ball milling pretreatment are: under a nitrogen atmosphere, a rotation speed of 150~200 rpm, and a time of 5~6 h.

[0007] Furthermore, in step 1, the mass ratio of adhesive, LMFP, PVP, conductive agent and AlOOH is 7: (64~80): (0.3~1.4): (3~4): (2~8); In step 1, the solid content of the primer slurry is 30-35%.

[0008] Furthermore, in step 1, the adhesive is PVDF (polyvinylidene fluoride). In step 1, the solvent is NMP (N-methyl-2-pyridinyl ketone). In step 1, the conductive agent is Li400.

[0009] Furthermore, in step 2, the coating speed is 30~40m / min; In step 2, the drying process conditions are: temperature 115~125℃, time 1~2h.

[0010] Furthermore, in step 2, the surface density of the primer slurry is 3.0~4.0 g / m². 2 ; In step 2, the coating thickness of the primer slurry is 1~3μm; In step 2, the thickness of the aluminum foil is 8~12μm.

[0011] This invention also provides an application of a base-coated current collector to improve the cycle life of lithium batteries, specifically including the following process: S1: Coat the positive electrode slurry onto the upper and lower surfaces of the primer current collector, and dry it to obtain the positive electrode sheet; S2: Coat the upper and lower surfaces of the copper foil with the negative electrode slurry, and dry it to obtain the negative electrode sheet; S3: The positive and negative electrode sheets are rolled, slit, and die-cut, and then stacked with the separator in the order of "positive electrode sheet-separator-negative electrode sheet-separator". The electrolyte is injected and the cells are formed to form a capacity, thus obtaining a soft-pack battery.

[0012] Furthermore, in S1, the coating thickness of the positive electrode slurry is 50~100μm.

[0013] Furthermore, in S1, the positive electrode slurry is obtained by mixing NCM811 (lithium nickel cobalt manganese oxide), PVDF, and Super P (conductive carbon black) in a mass ratio of (95.5~96.2):(1.5~1.8):2 and stirring until homogeneous.

[0014] Furthermore, in S2, the coating thickness of the negative electrode slurry is 60~100μm.

[0015] Furthermore, in S2, the negative electrode slurry is obtained by mixing artificial graphite, CMC (carboxymethyl cellulose), SBR (styrene-butadiene rubber), and Super P in a mass ratio of (90~95):(2.0~2.5):(1.5~1.7):(0.5~0.8) and stirring evenly.

[0016] Furthermore, in S2, the thickness of the copper foil is 6~8μm.

[0017] Furthermore, in S1 and S2, the drying process conditions are: temperature 120~140℃, time 1~2h.

[0018] Furthermore, in S3, the electrolyte is obtained by mixing LiPF6 (lithium tetrafluoroborate), DEC (diethyl carbonate), EC (ethylene carbonate), EMC (methyl ethyl carbonate), VC (ethylene carbonate), and PS (propane sulfonate lactone) in a mass ratio of 2:3:4:3:0.3:0.2.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. This application improves the cycle performance of lithium batteries by applying a slurry to aluminum foil and increases the capacity retention rate of the battery after long cycles. The stable olivine structure and high voltage platform of LMFP in the slurry can share some of the voltage stress and reduce the degree of phase transition (H2→H3 phase) of NCM. At the same time, LMFP has better thermal stability than NCM material and is difficult to decompose at high temperature, which can play a role in protecting the structural stability of NCM material at high temperature. 2. The AlOOH in the bottom coating slurry of this application has high mechanical strength. A small amount of addition can suppress the material shedding caused by the volume expansion of LMFP after long cycle. In addition, the boehmite has excellent thermal stability to prevent heat spread inside the battery, thereby improving the cycle performance of the battery.

[0020] 3. The addition of conductive agent Li400 in the primer slurry of this application can compensate for the conductivity loss of LMFP and AlOOH, and ensure rapid lithium ion transport.

[0021] 4. In this application, in order to ensure the coating stability of the primer slurry, the PVDF content is also controlled. If the PVDF content is too high, the slurry viscosity will be high, which is not conducive to rapid coating. If the PVDF content is too low, the viscosity will be too low, the slurry fluidity will be good, which will cause overflow on both sides of the coating area. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0023] In the following specific implementation; The adhesive is PVDF, grade Solvay 5130; The solvent is NMP; Boehmite, 10,000 mesh, specific surface area 5.07 m² 2 / g; Conductive agent, model number Li400; Super P, branded as Temico, has a particle size of 40nm and a specific surface area of ​​62m². 2 / g; Artificial graphite, model number FSN-1; Aluminum foil, 12μm thick.

[0024] Example 1: A method for preparing a base coating current collector to improve the cycle life of lithium batteries, comprising the following steps: Step 1: Mix the binder and solvent, disperse evenly, and then add the pre-treated LMFP, PVP, conductive agent, and AlOOH sequentially. Stir evenly to obtain a primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil and dry to obtain a primer current collector. In Step 1, the ball milling pretreatment conditions are: 200 rpm under a nitrogen atmosphere for 6 hours. In Step 1, the mass ratio of binder, LMFP, PVP, conductive agent, and AlOOH is 7:80:1:4:8. In Step 1, the solid content of the primer slurry is 30%. In Step 2, the coating speed is 40 m / min. In Step 2, the drying conditions are: 125℃ for 2 hours. In Step 2, the surface density of the primer slurry is 4.0 g / m³. 2 In step 2, the coating thickness of the primer slurry is 3μm.

[0025] Example 2: A method for preparing a base coating current collector to improve the cycle life of lithium batteries, comprising the following steps: Step 1: Mix the binder and solvent, disperse evenly, and then add the pre-treated LMFP, PVP, conductive agent, and AlOOH sequentially. Stir evenly to obtain a primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil and dry to obtain a primer current collector. In Step 1, the ball milling pretreatment conditions are: 200 rpm under a nitrogen atmosphere for 6 hours. In Step 1, the mass ratio of binder, LMFP, PVP, conductive agent, and AlOOH is 7:73:1:4:7. In Step 1, the solid content of the primer slurry is 30%. In Step 2, the coating speed is 40 m / min. In Step 2, the drying conditions are: temperature 125℃ for 2 hours. In Step 2, the surface density of the primer slurry is 4.0 g / m³. 2 In step 2, the coating thickness of the primer slurry is 3μm.

[0026] Example 3: A method for preparing a base coating current collector to improve the cycle life of lithium batteries, comprising the following steps: Step 1: Mix the binder and solvent, disperse evenly, and then add the pre-treated LMFP, PVP, conductive agent, and AlOOH sequentially. Stir evenly to obtain a primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil and dry to obtain a primer current collector. In Step 1, the ball milling pretreatment conditions are: 200 rpm under a nitrogen atmosphere for 6 hours. In Step 1, the mass ratio of binder, LMFP, PVP, conductive agent, and AlOOH is 7:78:1:4:6. In Step 1, the solid content of the primer slurry is 30%. In Step 2, the coating speed is 40 m / min. In Step 2, the drying conditions are: 125℃ for 2 hours. In Step 2, the surface density of the primer slurry is 4.0 g / m³. 2 In step 2, the coating thickness of the primer slurry is 3μm.

[0027] Example 4: A method for preparing a base coating current collector to improve the cycle life of lithium batteries, comprising the following steps: Step 1: Mix the binder and solvent, disperse evenly, and then add the pre-treated LMFP, PVP, conductive agent, and AlOOH sequentially. Stir evenly to obtain a primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil and dry to obtain a primer current collector. In Step 1, the ball milling pretreatment conditions are: 200 rpm under a nitrogen atmosphere for 6 hours. In Step 1, the mass ratio of binder, LMFP, PVP, conductive agent, and AlOOH is 7:74:1:3.5:6.5. In Step 1, the solid content of the primer slurry is 30%. In Step 2, the coating speed is 40 m / min. In Step 2, the drying conditions are: 125℃ for 2 hours. In Step 2, the surface density of the primer slurry is 4.0 g / m³. 2 In step 2, the coating thickness of the primer slurry is 3μm.

[0028] Example 5: A method for preparing a base coating current collector to improve the cycle life of lithium batteries, comprising the following steps: Step 1: Mix the binder and solvent, disperse evenly, and then add the pre-treated LMFP, PVP, conductive agent, and AlOOH sequentially. Stir evenly to obtain a primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil and dry to obtain a primer current collector. In Step 1, the ball milling pretreatment conditions are: 200 rpm under a nitrogen atmosphere for 6 hours. In Step 1, the mass ratio of binder, LMFP, PVP, conductive agent, and AlOOH is 7:70:1:3:2. In Step 1, the solid content of the primer slurry is 30%. In Step 2, the coating speed is 40 m / min. In Step 2, the drying conditions are: temperature 125℃ for 2 hours. In Step 2, the surface density of the primer slurry is 4.0 g / m³. 2 In step 2, the coating thickness of the primer slurry is 3μm.

[0029] Example 6: A method for preparing a base coating current collector to improve the cycle life of lithium batteries, comprising the following steps: Step 1: Mix the binder and solvent, disperse evenly, and then add the pre-treated LMFP, PVP, conductive agent, and AlOOH sequentially. Stir evenly to obtain a primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil and dry to obtain a primer current collector. In Step 1, the ball milling pretreatment conditions are: 200 rpm under a nitrogen atmosphere for 6 hours. In Step 1, the mass ratio of binder, LMFP, PVP, conductive agent, and AlOOH is 7:64:1:4:8. In Step 1, the solid content of the primer slurry is 30%. In Step 2, the coating speed is 40 m / min. In Step 2, the drying conditions are: 125℃ for 2 hours. In Step 2, the surface density of the primer slurry is 4.0 g / m³. 2 In step 2, the coating thickness of the primer slurry is 3μm.

[0030] Example 7: A method for preparing a base coating current collector to improve the cycle life of lithium batteries, comprising the following steps: Step 1: Mix the binder and solvent, disperse evenly, and then add the pre-treated LMFP, PVP, conductive agent, and AlOOH sequentially. Stir evenly to obtain a primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil and dry to obtain a primer current collector. In Step 1, the ball milling pretreatment conditions are: 200 rpm under a nitrogen atmosphere for 6 hours. In Step 1, the mass ratio of binder, LMFP, PVP, conductive agent, and AlOOH is 7:72:1:4:8. In Step 1, the solid content of the primer slurry is 30%. In Step 2, the coating speed is 40 m / min. In Step 2, the drying conditions are: 125℃ for 2 hours. In Step 2, the surface density of the primer slurry is 4.0 g / m³. 2 In step 2, the coating thickness of the primer slurry is 3μm.

[0031] Example 8: A method for preparing a base coating current collector to improve the cycle life of lithium batteries, comprising the following steps: Step 1: Mix the binder and solvent, disperse evenly, and then add the pre-treated LMFP, PVP, conductive agent, and AlOOH sequentially. Stir evenly to obtain a primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil and dry to obtain a primer current collector. In Step 1, the ball milling pretreatment conditions are: 200 rpm under a nitrogen atmosphere for 6 hours. In Step 1, the mass ratio of binder, LMFP, PVP, conductive agent, and AlOOH is 7:66:1:4:6. In Step 1, the solid content of the primer slurry is 30%. In Step 2, the coating speed is 40 m / min. In Step 2, the drying conditions are: 125℃ for 2 hours. In Step 2, the surface density of the primer slurry is 4.0 g / m³. 2 In step 2, the coating thickness of the primer slurry is 3μm.

[0032] Example 9: A method for preparing a base coating current collector to improve the cycle life of lithium batteries, comprising the following steps: Step 1: Mix the binder and solvent, disperse evenly, and then add the pre-treated LMFP, PVP, conductive agent, and AlOOH sequentially. Stir evenly to obtain a primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil and dry to obtain a primer current collector. In Step 1, the ball milling pretreatment conditions are: 200 rpm under a nitrogen atmosphere for 6 hours. In Step 1, the mass ratio of binder, LMFP, PVP, conductive agent, and AlOOH is 7:72:1:4:6. In Step 1, the solid content of the primer slurry is 30%. In Step 2, the coating speed is 40 m / min. In Step 2, the drying conditions are: 125℃ for 2 hours. In Step 2, the surface density of the primer slurry is 4.0 g / m³. 2 In step 2, the coating thickness of the primer slurry is 3μm.

[0033] Example 10: A method for preparing a base coating current collector to improve the cycle life of lithium batteries, comprising the following steps: Step 1: Mix the binder and solvent, disperse evenly, and then add the pre-treated LMFP, PVP, conductive agent, and AlOOH sequentially. Stir evenly to obtain a primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil and dry to obtain a primer current collector. In Step 1, the ball milling pretreatment conditions are: under a nitrogen atmosphere, rotation speed 150-200 rpm, time 5-6 h; in Step 1, the mass ratio of binder, LMFP, PVP, conductive agent, and AlOOH is 7:64:0.4:3:2; in Step 1, the solid content of the primer slurry is 30%; in Step 2, the coating speed is 40 m / min; in Step 2, the drying conditions are: temperature 125℃, time 2 h; in Step 2, the surface density of the primer slurry is 4.0 g / m³. 2 In step 2, the coating thickness of the primer slurry is 3μm.

[0034] Example 11: A method for preparing a base coating current collector to improve the cycle life of lithium batteries, comprising the following steps: Step 1: Mix the binder and solvent, disperse evenly, and then add the pre-treated LMFP, PVP, conductive agent, and AlOOH sequentially. Stir evenly to obtain a primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil and dry to obtain a primer current collector. In Step 1, the ball milling pretreatment conditions are: 200 rpm under a nitrogen atmosphere for 6 hours. In Step 1, the mass ratio of binder, LMFP, PVP, conductive agent, and AlOOH is 7:72:1.4:4:6. In Step 1, the solid content of the primer slurry is 30%. In Step 2, the coating speed is 40 m / min. In Step 2, the drying conditions are: 125℃ for 2 hours. In Step 2, the surface density of the primer slurry is 4.0 g / m³. 2 In step 2, the coating thickness of the primer slurry is 3μm.

[0035] Example 12: A method for preparing a base coating current collector to improve the cycle life of lithium batteries, comprising the following steps: Step 1: Mix the binder and solvent, disperse evenly, and then add the pre-treated LMFP, PVP, conductive agent, and AlOOH sequentially. Stir evenly to obtain a primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil and dry to obtain a primer current collector. In Step 1, the ball milling pretreatment conditions are: 180 rpm under a nitrogen atmosphere for 5.5 hours. In Step 1, the mass ratio of binder, LMFP, PVP, conductive agent, and AlOOH is 7:80:1:4:8. In Step 1, the solid content of the primer slurry is 33%. In Step 2, the coating speed is 35 m / min. In Step 2, the drying conditions are: 120℃ for 1.5 hours. In Step 2, the surface density of the primer slurry is 3.5 g / m³. 2 In step 2, the coating thickness of the primer slurry is 2μm.

[0036] Example 13: A method for preparing a base coating current collector to improve the cycle life of lithium batteries, comprising the following steps: Step 1: Mix the binder and solvent, disperse evenly, and then add the pre-treated LMFP, PVP, conductive agent, and AlOOH sequentially. Stir evenly to obtain a primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil and dry to obtain a primer current collector. In Step 1, the ball milling pretreatment conditions are: 150 rpm under a nitrogen atmosphere for 5-6 hours; the mass ratio of binder, LMFP, PVP, conductive agent, and AlOOH in Step 1 is 7:80:1:4:8; the solid content of the primer slurry in Step 1 is 30%; the coating speed in Step 2 is 30 m / min; the drying conditions in Step 2 are: temperature 115℃ for 1 hour; and the surface density of the primer slurry in Step 2 is 3.0 g / m³. 2 In step 2, the coating thickness of the primer slurry is 1 μm.

[0037] Comparative Example 1: Compared with Example 1, AlOOH was not added to the primer slurry, and all other conditions remained the same as in Example 1, specifically: Step 1: Mix the binder and solvent, disperse evenly, and then add the pre-treated LMFP, PVP, and conductive agent sequentially. Stir evenly to obtain a primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil and dry to obtain a primer current collector. In Step 1, the ball milling pretreatment conditions are: 200 rpm under a nitrogen atmosphere for 6 hours; the mass ratio of binder, LMFP, PVP, and conductive agent in Step 1 is 7:80:1:4; the solid content of the primer slurry in Step 1 is 30%; the coating speed in Step 2 is 40 m / min; the drying conditions in Step 2 are: 125℃ for 2 hours; and the surface density of the primer slurry in Step 2 is 4.0 g / m³. 2 In step 2, the coating thickness of the primer slurry is 3μm.

[0038] Comparative Example 2: Compared with Example 1, no conductive agent was added to the primer slurry, and all other conditions remained the same as in Example 1, specifically: Step 1: Mix the binder and solvent, disperse evenly, and then add the pre-treated LMFP, PVP, and AlOOH sequentially. Stir evenly to obtain a primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil and dry to obtain a primer current collector. In Step 1, the ball milling pretreatment conditions are: 200 rpm under a nitrogen atmosphere for 6 hours; the mass ratio of binder, LMFP, PVP, and AlOOH in Step 1 is 7:80:1:8; the solid content of the primer slurry in Step 1 is 30%; the coating speed in Step 2 is 40 m / min; the drying conditions in Step 2 are: 125℃ for 2 hours; and the surface density of the primer slurry in Step 2 is 4.0 g / m³. 2 In step 2, the coating thickness of the primer slurry is 3μm.

[0039] Comparative Example 3: Compared with Example 1, without adding PVP to the primer slurry, and with all other conditions unchanged, the viscosity of the primer slurry increased sharply, making it impossible to coat normally.

[0040] Comparative Example 4: The aluminum foil was used directly without applying a primer to its surface.

[0041] Experiment: The primer current collectors obtained in the examples and comparative examples were used to make soft-pack batteries, and the performance of the soft-pack batteries was tested. Fabrication of pouch cells: S1: The positive electrode slurry is coated onto the upper and lower surfaces of the primer current collector and dried to obtain the positive electrode sheet; S2: The negative electrode slurry is coated onto the upper and lower surfaces of the copper foil and dried to obtain the negative electrode sheet; S3: The positive and negative electrode sheets are rolled, slit, and die-cut, and then stacked with the separator in the order of "positive electrode sheet-separator-negative electrode sheet-separator", assembled, injected with electrolyte, and formed into a capacity test to obtain a soft-pack battery; In S1, the coating thickness of the positive electrode slurry is 100μm; In S1, the positive electrode slurry is obtained by mixing NCM811, PVDF, and Super P in a mass ratio of 96.2:1.8:2 and stirring evenly; In S2, the coating thickness of the negative electrode slurry is 100μm; In S2, the negative electrode slurry is obtained by mixing artificial graphite, CMC, SBR, and Super P. P is mixed in a mass ratio of 95:2.5:1.7:0.8 and stirred until homogeneous; in S2, the thickness of the copper foil is 8μm; in S1 and S2, the drying process conditions are: temperature 140℃, time 2h; in S3, the electrolyte is obtained by mixing LiPF6, DEC, EC, EMC, VC and PS in a mass ratio of 2:3:4:3:0.3:0.2. The soft-pack battery was charged and discharged using a charge-discharge tester. The voltage range was 2.8-4.2V and the discharge current was 1C. The capacity retention rate was tested after 500, 800 and 1000 cycles.

[0042] Based on the data in the table above, the following conclusions can be drawn: Compared with Example 1, Comparative Example 1 did not add AlOOH to the primer slurry, and the capacity retention rate decreased after cycling. This is because the thermal stability of AlOOH can prevent heat propagation inside the battery, thereby improving the cycle performance of the battery. Compared with Example 1, Comparative Example 2 did not add a conductive agent to the base coating slurry, and the capacity retention rate decreased after cycling. This is because the conductive agent Li400 can compensate for the conductivity loss of LMFP and AlOOH, ensure the rapid transport of lithium ions, and help improve the cycle performance of the battery. Compared with Example 1, Comparative Example 3 did not add PVP to the primer slurry. Without the introduction of PVP, the slurry was difficult to disperse, and the viscosity of the primer slurry increased sharply, resulting in the inability to coat normally, so it could not be tested. Compared with Example 1, Comparative Example 4, which uses aluminum foil directly to prepare pouch cells, showed a more significant decrease in capacity retention after cycling. In summary, the settings for the materials used and their quantities, as well as the process conditions in this application, can promote the overall improvement of the cycle performance of the manufactured soft-pack battery.

[0043] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing a base-coated current collector to improve the cycle life of lithium batteries, characterized in that: Includes the following steps: Step 1: Mix the binder and solvent, disperse them evenly, and then add the ball-milled pretreated LMFP, PVP, conductive agent and AlOOH in sequence. Stir evenly to obtain the primer slurry. Step 2: Apply the primer slurry evenly to the upper and lower surfaces of the aluminum foil, and dry it to obtain the primer current collector; In step 1, the mass ratio of adhesive, LMFP, PVP, conductive agent and AlOOH is 7: (64~80): (0.3~1.4): (3~4): (2~8).

2. The method for preparing a base coating current collector to improve the cycle life of lithium batteries according to claim 1, characterized in that: In step 1, the process conditions for ball mill pretreatment are: under a nitrogen atmosphere, a rotation speed of 150~200 rpm, and a time of 5~6 h.

3. The method for preparing a base coating current collector to improve the cycle life of a lithium battery according to claim 2, characterized in that: In step 1, the solid content of the primer slurry is 30-35%.

4. The method for preparing a base coating current collector to improve the cycle life of a lithium battery according to claim 3, characterized in that: In step 2, the coating speed is 30~40m / min.

5. The method for preparing a base coating current collector to improve the cycle life of a lithium battery according to claim 4, characterized in that: In step 2, the drying process conditions are: temperature 115~125℃, time 1~2h.

6. The method for preparing a base coating current collector to improve the cycle life of a lithium battery according to claim 5, characterized in that: In step 2, the coating surface density of the primer slurry is 3.0-4.0 g / m 2 .

7. The method for preparing a base coating current collector to improve the cycle life of a lithium battery according to claim 6, characterized in that: In step 2, the coating thickness of the primer slurry is 1~3μm.

8. The method for preparing a base coating current collector to improve the cycle life of a lithium battery according to claim 7, characterized in that: In step 1, the adhesive is PVDF; In step 1, the solvent is NMP.

9. The method for preparing a base coating current collector to improve the cycle life of a lithium battery according to claim 8, characterized in that: In step 1, the conductive agent is Li400.

10. The application of a primer current collector for improving the cycle life of lithium batteries according to any one of claims 1 to 9, characterized in that: Used to manufacture pouch cells.

Images