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CN-122000294-A - Negative electrode plate, preparation method of negative electrode plate and battery

CN122000294ACN 122000294 ACN122000294 ACN 122000294ACN-122000294-A

Abstract

The embodiment of the application provides a negative electrode plate, a preparation method of the negative electrode plate and a battery, and relates to the technical field of batteries. The negative electrode plate comprises a current collector, a first coating and a second coating, wherein the first coating is arranged on at least one surface of the current collector, the second coating is arranged on the surface, deviating from the current collector, of the first coating, and the first coating comprises carbon nano onion. According to the application, the first coating with the carbon nano onion is arranged between the current collector and the second coating, the first coating is used as a transition layer, and the second coating is used as a negative electrode active layer. The first coating has elastic deformation, and can absorb the expansion stress generated by the second coating when the battery is charged and discharged, so that the second coating is prevented from falling powder, the peeling strength between the second coating and the current collector is effectively improved, and the performance of the battery is further improved.

Inventors

  • ZHANG YONG
  • ZHANG HENG
  • WU ZHIFEI
  • LIAO YULI
  • PENG YANQIU

Assignees

  • 武汉亿纬储能有限公司

Dates

Publication Date
20260508
Application Date
20260206

Claims (19)

  1. 1. The negative electrode plate is characterized by comprising a current collector, a first coating and a second coating, wherein the first coating is arranged on at least one surface of the current collector, the second coating is arranged on the surface, facing away from the current collector, of the first coating, and the first coating comprises carbon nano onions.
  2. 2. The negative electrode tab of claim 1, wherein the thickness ratio of the first coating and the second coating is 0.1% -0.2%.
  3. 3. The negative electrode tab of claim 2, wherein the first coating has a thickness of 90nm-100nm and the second coating has a thickness of 50 μm-70 μm.
  4. 4. The negative electrode tab of claim 1, wherein the first coating comprises a dispersant and a first binder, wherein the mass ratio of the carbon nano-onions, the dispersant and the first binder is (80-100): 3-8): 1.5-4.
  5. 5. The negative electrode tab of claim 4, wherein the dispersant comprises one or more of polyvinylpyrrolidone, polyvinyl alcohol, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, polyethylene glycol monooctylphenyl ether, and polysorbate, and the first binder comprises one or more of sodium carboxymethyl cellulose, polyacrylic acid, sodium polyacrylate, and sodium alginate.
  6. 6. The negative electrode tab of claim 1, wherein the second coating comprises graphite, a conductive agent, and a second binder, wherein the mass ratio of the graphite, the conductive agent, and the second binder is (90-95): 2-3): 6-8.
  7. 7. The negative electrode tab of claim 6, wherein the conductive agent comprises carbon black and carbon nanotubes in a mass ratio of 2:1 or 1:1, and the second binder comprises styrene butadiene rubber and sodium carboxymethyl cellulose in a mass ratio of (3:2) to (2:1).
  8. 8. The negative electrode tab of claim 1, wherein the contact angle of the current collector is 22 ° -28 °, and/or the surface roughness of the current collector is less than or equal to 3.5 μm.
  9. 9. The negative electrode tab of claim 1, further comprising a third coating layer between the current collector and the first coating layer, the third coating layer comprising a silane coupling agent.
  10. 10. A method for producing a negative electrode sheet according to any one of claims 1 to 9, comprising the steps of: Coating a first slurry on at least one surface of the current collector, and obtaining a first coating after first drying, wherein the first slurry comprises carbon nano-onions; coating a second slurry on the surface of the first coating, which faces away from the current collector, and obtaining the second coating after second drying; And rolling the current collector, the first coating and the second coating to obtain the negative electrode plate.
  11. 11. The method of manufacturing a negative electrode sheet according to claim 10, wherein the preparation of the first slurry includes: The carbon nano onion and the dispersing agent are dissolved in a first solvent, a first binder is added after first mixing treatment, and the first slurry is obtained after second mixing treatment and first filtering, wherein the mass ratio of the carbon nano onion to the dispersing agent to the first binder is (80-100): (3-8): (1.5-4), the first solvent comprises water, and the solid content of the first slurry is 8.5-9.5 wt%.
  12. 12. The method of manufacturing a negative electrode sheet according to claim 11, wherein at least one of the following characteristics is satisfied: the viscosity of the first slurry is 3500 Pa.s-4500 Pa.s; The average grain size of the first slurry is 120nm-180nm; The variation coefficient value of the first slurry is less than or equal to 10%; the sedimentation rate of the first slurry for 24 hours is less than or equal to 5 percent.
  13. 13. The method of producing a negative electrode sheet according to claim 11 or 12, wherein the first mixing treatment includes at least one of: Stirring for 1-5 h at 50-60deg.C by using a stirrer; Dispersing treatment with a high shear emulsifying machine for 0.5-2h at 30-60deg.C; Performing ultrasonic dispersion treatment for 60s-30min at 20-50deg.C; The second mixing treatment comprises stirring treatment by adopting a stirrer, wherein the stirring time is 15-25 min, and the stirring temperature is 50-60 ℃.
  14. 14. The method of manufacturing a negative electrode sheet according to claim 10, wherein the manufacturing of the second slurry includes: And dissolving graphite, a conductive agent and a second binder in a second solvent, and obtaining second slurry after third mixing treatment and second filtering, wherein the mass ratio of the graphite to the conductive agent to the second binder is (90-95): (2-3): (6-8), the second solvent comprises water, and the solid content of the second slurry is 51-53 wt%.
  15. 15. The method for preparing a negative electrode sheet according to claim 14, wherein, The viscosity of the second slurry is 8000 Pa.s-10000 Pa.s; And/or the sedimentation rate of the second slurry for 1 hour is less than or equal to 3 percent.
  16. 16. The method of claim 10, wherein the first drying comprises, Drying treatment is carried out by adopting pre-drying, wherein the drying temperature is 50-70 ℃, the air speed is 2-4 m/s, and the drying time is 2-10 min, and the solvent residue rate after the pre-drying is 50-60%; And/or drying treatment is carried out by adopting high-temperature curing, wherein the gas atmosphere is nitrogen atmosphere with oxygen content less than or equal to 5%, the drying temperature is 100-120 ℃, and the drying time is 5-30 min, and the solvent residue rate after high-temperature curing is less than or equal to 0.5%.
  17. 17. The method for preparing a negative electrode sheet according to claim 10, wherein before the first slurry is coated on at least one surface of the current collector and the first coating is obtained after the first drying, the method further comprises the step of pre-treating the current collector, the pre-treating step comprising: Immersing the current collector into an alkaline solution for alkaline washing, wherein the alkaline solution comprises at least one of sodium hydroxide and sodium dodecyl sulfate, and the alkaline washing time is 1-5 min; Immersing the alkaline washed current collector into an acidic solution for pickling, wherein the acidic solution comprises sulfuric acid, and the pickling time is 30s-3min; and drying the current collector subjected to alkaline washing and acid washing, wherein the drying time is 1-5 min, and the drying temperature is 70-90 ℃.
  18. 18. The method according to claim 17, wherein the pretreatment step includes hydrolyzing a silane coupling agent under acidic conditions to obtain a hydrolyzed solution, coating the hydrolyzed solution on at least one surface of the current collector after the alkaline washing and the acid washing, and then performing a third drying treatment, before drying the current collector after the alkaline washing and the acid washing, wherein the concentration of the silane coupling agent is 0.2wt% to 0.8wt%.
  19. 19. A battery comprising a positive electrode sheet, a separator, an electrolyte, and the negative electrode sheet of any one of claims 1-9.

Description

Negative electrode plate, preparation method of negative electrode plate and battery Technical Field The application belongs to the technical field of batteries, and particularly relates to a negative electrode plate, a preparation method of the negative electrode plate and a battery. Background The energy storage industry is moving into a large energy storage era, the size design of the battery core is larger and larger, and the requirement on the volume energy density is higher and higher. In order to improve the volume energy density of the battery cell, the current battery cell design mainly focuses on the high-voltage compaction and high-voltage compaction directions of the electrode. By improving the compaction density and the compaction degree of the electrode, more electric energy can be stored in a limited space, so that the overall energy density of the battery cell is improved. Based on this, thick electrode design is an important option, as compared to thin electrodes, thick motors can carry more active material at the same area to increase the capacity of the cell. However, the thick electrode design is easy to cause the coating of the negative electrode graphite material system to generate a powder falling phenomenon, and the volume of the negative electrode graphite layer is changed due to the breathing effect of the expansion force of the negative electrode graphite layer in the use process of charging and discharging of the battery cell, so that the powder falling risk of the negative electrode graphite layer is also easy to cause. Disclosure of Invention The application provides a negative electrode plate, a preparation method of the negative electrode plate and a battery. Through setting up first coating between electric current body and second coating, the expansion of second coating can be restrained to first coating, effectively promotes the peel strength of second coating on electric current body, improves the cycle of negative pole piece and falls the whitewashed phenomenon to promote the performance of battery. In a first aspect, the application provides a negative electrode plate, which comprises a current collector, a first coating and a second coating, wherein the first coating is arranged on at least one surface of the current collector, the second coating is arranged on the surface of the first coating, which is away from the current collector, and the first coating comprises carbon nano onions. According to the application, the first coating is arranged between the current collector and the second coating, and the first coating is used as the transition layer, so that a strong interface combination can be formed between the current collector and the second coating. Meanwhile, the carbon nano onion material can elastically deform and provide buffering for the second coating. When the second coating changes in volume, the first coating can absorb the stress generated by volume expansion of the second coating, so that the problem that the second coating is easy to peel due to the fact that the second coating is directly coated on a current collector can be effectively solved, and the powder dropping phenomenon of the negative electrode plate is improved. In some embodiments, the thickness ratio of the first coating layer to the second coating layer is 0.1% to 0.2%. In some embodiments, the first coating has a thickness of 90nm to 100nm and the second coating has a thickness of 50 μm to 70 μm. In some embodiments, the first coating includes a dispersant and a first binder, wherein the mass ratio of carbon nano-onions, dispersant and first binder is (80-100): 3-8): 1.5-4. In some embodiments, the dispersant comprises one or more of polyvinylpyrrolidone, polyvinyl alcohol, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, polyethylene glycol monooctylphenyl ether, and polysorbate, and the first binder comprises one or more of sodium carboxymethyl cellulose, polyacrylic acid, sodium polyacrylate, and sodium alginate. In some embodiments, the second coating comprises graphite, a conductive agent, and a second binder, wherein the mass ratio of graphite, conductive agent, and second binder is (90-95): 2-3): 6-8. In some embodiments, the conductive agent comprises carbon black and carbon nanotubes, wherein the mass ratio of carbon black to carbon nanotubes is 2:1 or 1:1. In some embodiments, the mass ratio of styrene butadiene rubber to sodium carboxymethyl cellulose ranges from 3:2 to 2:1. In some embodiments, the contact angle of the current collector is 22 ° -28 °. In some embodiments, the surface roughness of the current collector is less than or equal to 3.5 μm. In some embodiments, the negative electrode tab further comprises a third coating layer positioned between the current collector and the first coating layer, the third coating layer for connecting the current collector and the first coating layer. The application provides a preparation method of a negative electrode