Search

CN-122000422-A - Battery cell, manufacturing method thereof, battery device and electricity utilization device

CN122000422ACN 122000422 ACN122000422 ACN 122000422ACN-122000422-A

Abstract

The application provides a battery cell, a manufacturing method thereof, a battery device and an electric device. The battery monomer comprises an electrode assembly, wherein the electrode assembly comprises an anode pole piece, a cathode pole piece and a separator positioned between the anode pole piece and the cathode pole piece, the cathode pole piece comprises a cathode current collector and a cathode film layer, the cathode film layer is arranged on at least one side of the cathode current collector, the cathode film layer comprises a cathode active material and a conductive agent, the cathode active material comprises a carbon-based material and a silicon-based material, the conductive agent comprises a flaky carbon-based conductive agent, the cathode film layer is a single layer or multiple layers, and the mass content of silicon element in the cathode film layer with the flaky carbon-based conductive agent and the silicon-based material is 30% -80%. The conductivity and the stability in circulation of the silicon-containing cathode are improved.

Inventors

  • WU KAI
  • WU LONGSHENG
  • CHEN XINGBU
  • WU LILI
  • SUN XIN
  • LI XUAN

Assignees

  • 宁德时代新能源科技股份有限公司

Dates

Publication Date
20260508
Application Date
20241104

Claims (19)

  1. 1. The battery cell comprises an electrode assembly, wherein the electrode assembly comprises a positive electrode plate, a negative electrode plate and a separator arranged between the positive electrode plate and the negative electrode plate, the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer, the negative electrode film layer is arranged on at least one side of the negative electrode current collector, the negative electrode film layer comprises a negative electrode active material and a conductive agent, the negative electrode active material comprises a carbon-based material and a silicon-based material, the conductive agent comprises a sheet-shaped carbon-based conductive agent, the negative electrode film layer is a single layer or multiple layers, and the mass content of silicon element in the sheet-shaped carbon-based conductive agent and the negative electrode film layer of the silicon-based material is 30% -80%.
  2. 2. The battery cell according to claim 1, wherein the sheet-like carbon-based conductive agent has an average diameter length of 0.5 μm to 10 μm, optionally 0.6 μm to 7 μm.
  3. 3. The battery cell according to claim 1 or 2, wherein the sheet-like carbon-based conductive agent has an average thickness of 0.1 μm to 5 μm, optionally 0.2 μm to 2 μm, and optionally the ratio of the average thickness to the average diameter length of the sheet-like carbon-based conductive agent is 1/30 to 1/3.
  4. 4. The battery cell according to any one of claims 1 to 3, wherein the sheet-shaped carbon-based conductive agent has a powder resistivity of 1mΩ -cm-15 mΩ -cm at a pressure of 12 MPa.
  5. 5. The battery cell according to any one of claims 1 to 4, wherein the platy carbon-based conductive agent comprises any one or more of platy graphite, platy graphene.
  6. 6. The battery cell according to any one of claims 1 to 5, wherein, in a cross-sectional area of the anode film layer having the silicon-based material in a thickness direction of the anode tab, an area ratio of the sheet-shaped carbon-based conductive agent to the silicon-based material is 4% to 20%.
  7. 7. The battery cell according to any one of claims 1 to 6, wherein the conductive agent further comprises a dot-shaped conductive agent and/or a line-shaped conductive agent, Optionally, the punctiform conductive agent comprises one or more of superconductive carbon, acetylene black, carbon black, ketjen black or carbon dots; optionally, the linear conductive agent includes carbon nanotubes and/or carbon nanofibers.
  8. 8. The battery cell of any one of claims 1 to 7, wherein the carbon-based material comprises any one or more of artificial graphite, natural graphite, soft carbon, and hard carbon.
  9. 9. The battery cell of any one of claims 1-8, wherein the silicon-based material comprises one or more of elemental silicon, a silicon oxygen compound, a silicon carbon composite, and a silicon alloy.
  10. 10. The battery cell according to any one of claims 1 to 9, wherein a mass content of the silicon element in the anode film layer is 30% -55%.
  11. 11. The battery cell of claim 10, wherein the negative electrode film is multilayered, at least a portion of the sheet-like carbon-based conductive agent being disposed in the same negative electrode film as the silicon-based material.
  12. 12. The battery cell of claim 11, wherein the negative electrode film layer comprises: The first negative electrode film layer is arranged on one side of the negative electrode current collector; the second negative electrode film layer is arranged on one side of the first negative electrode film layer, which is far away from the negative electrode current collector, The silicon-based material is independently arranged in each of the first negative electrode film layer and the second negative electrode film layer.
  13. 13. The battery cell of claim 12, wherein the first and second anode films each independently comprise a binder, the silicon-based material is present in the first anode film at a greater mass content than in the second anode film, optionally the binder is present in the first anode film at a mass content greater than or equal to the binder in the second anode film, and/or the binder is present in the first anode film at a mass content of 5% -10%.
  14. 14. The battery cell of claim 12, wherein the silicon-based material is present in the second negative electrode film in a greater mass content than in the first negative electrode film, the ratio of the thickness of the first negative electrode film to the thickness of the second negative electrode film being (1:4) - (4:1), optionally (6:5) - (1:1).
  15. 15. A method of making a battery cell of any one of claims 1 to 14, the method comprising a process of making a negative electrode tab, the process comprising: Mixing a negative electrode active material, a conductive agent and a solvent to form a negative electrode slurry, wherein the negative electrode active material comprises a carbon-based material and a silicon-based material, and the conductive agent comprises a platy carbon-based conductive agent; and (3) after the negative electrode slurry is arranged on a negative electrode current collector, tabletting and drying are carried out, so that the negative electrode plate is obtained.
  16. 16. The production method according to claim 15, wherein the negative electrode slurry having a solid content of 30 to 40% has a viscosity of 8000Pa.s to 12000mPa.s at 25 ℃ and a rotation speed of 60 rpm.
  17. 17. The manufacturing method according to claim 15 or 16, wherein the manufacturing process further comprises a process of coating the sheet-shaped carbon-based conductive agent on the surface of the silicon-based material, optionally by spray drying, before forming the anode slurry.
  18. 18. A battery device comprising a plurality of battery cells, wherein the battery cells comprise the battery cell of any one of claims 1 to 14.
  19. 19. An electrical device comprising the battery cell of any one of claims 1 to 14 or the battery device of claim 18 for storing or providing electrical energy.

Description

Battery cell, manufacturing method thereof, battery device and electricity utilization device Technical Field The present application relates to the field of battery technologies, and in particular, to a battery cell, a manufacturing method thereof, a battery device, and an electric device. Background In recent years, lithium ion batteries with high energy density are widely used in the electric automobile industry. Silicon has become a high-capacity anode material which is more applied at present by virtue of high gram capacity. However, the silicon material is used as the negative electrode of the lithium battery, and has the problems of poor cycle performance, large volume expansion and the like. The theoretical gram capacity of a pure silicon anode can be as high as 4200mAh/g (45 ℃). However, silicon has some problems that the electrochemical activity is low due to poor electric conductivity ①, and the ② high-silicon negative electrode plate can generate particle breakage and active substances are separated from a conductive network after repeated cyclic expansion, so that the active substances are deactivated. The above problems result in an insufficient cycle life of the cell, failing to meet the commercial demands. Disclosure of Invention The application provides a battery cell, a manufacturing method thereof, a battery device and an electric device, which are used for improving the conductivity of a silicon-containing negative electrode and the stability in circulation. The first aspect of the application provides a battery cell, comprising an electrode assembly, wherein the electrode assembly comprises a positive electrode plate, a negative electrode plate and a separator positioned between the positive electrode plate and the negative electrode plate, the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer, the negative electrode film layer is arranged on at least one side of the negative electrode current collector, the negative electrode film layer comprises a negative electrode active material and a conductive agent, the negative electrode active material comprises a carbon-based material and a silicon-based material, the conductive agent comprises a flaky carbon-based conductive agent, the negative electrode film layer is a single layer or multiple layers, and the mass content of silicon element in the negative electrode film layer with the flaky carbon-based conductive agent and the silicon-based material is 30% -80%. The flaky carbon-based conductive agent is not easy to agglomerate, can be uniformly covered on the surface of a silicon-based material to form a good conductive network and a buffer structure, and theoretically, compared with a particle conductive agent, the flaky carbon-based conductive agent can be in surface contact with particles of the silicon-based material, so that the interface electronic conduction of the low-conductivity silicon-based material is obviously improved, the activity of a negative electrode plate is improved, the flaky carbon-based conductive agent has certain flexibility, and can be buffered to a certain extent in the cyclic expansion and contraction process of the silicon-based material, so that the whole life cycle of the flaky carbon-based conductive agent is kept in good electrical contact with the particles of the silicon-based material, and the cycle life is prolonged. Meanwhile, the probability of direct contact between the silicon-based materials coated by the flaky carbon-based conductive agent is greatly reduced, and the hardness of the silicon-based material particles in the cyclic expansion and contraction process is controlled, so that the crushing and pulverization caused by extrusion among the silicon-based material particles are delayed, and the cyclic life is further prolonged. Experiments prove that when the mass content of silicon element in the film layer containing the silicon-based material is less than 30%, the carbon-based material fully wraps the silicon-based material, so that aggregation among silicon-based material particles is greatly reduced, and the conductivity and the buffering effect cannot be improved when the sheet-shaped carbon-based conductive agent is added. When the mass content of silicon element in the film layer containing the silicon-based material is above 30%, the sheet-like carbon-based conductive agent has a remarkable improvement effect on the conductivity and the cushioning effect. In any embodiment of the first aspect, the sheet-like carbon-based conductive agent has an average diameter length of 0.5 μm to 10 μm, optionally 0.6 μm to 7 μm. The conductive effect of the sheet-like carbon-based conductive agent can be further improved. In any embodiment of the first aspect, the sheet-like carbon-based conductive agent has an average thickness of 0.1 μm to 5 μm, alternatively 0.2 μm to 2 μm, and alternatively the ratio of the average thickness to the a