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CN-122000355-A - Negative plate, preparation method thereof and battery

CN122000355ACN 122000355 ACN122000355 ACN 122000355ACN-122000355-A

Abstract

The embodiment of the application discloses a negative electrode plate, a preparation method thereof and a battery, and belongs to the technical field of batteries, wherein the negative electrode plate comprises a negative electrode active layer, and the material of the negative electrode active layer comprises a negative electrode active material, a first conductive agent, a second conductive agent and a binder, wherein the conductivity of the first conductive agent is 500S/m-2000S/m, and the conductivity of the second conductive agent is 10 5 S/m-10 8 S/m. Wherein, the mass percent of the first conductive agent in the anode active layer is 10% -50%, and the mass percent of the second conductive agent in the anode active layer is 0.3% -0.6%. The negative plate provided by the embodiment of the application can construct a three-dimensional conductive network through the synergistic effect of the first conductive agent and the second conductive agent, so that the electron transmission efficiency is obviously improved, the capacity exertion rate is ensured, the circulation stability is improved, and the mechanical property is improved.

Inventors

  • Rong Mengke
  • TAN YANING
  • SUN PEILING
  • CAO LANG

Assignees

  • 惠州亿纬锂能股份有限公司

Dates

Publication Date
20260508
Application Date
20251226

Claims (12)

  1. 1. A negative electrode sheet characterized by comprising a negative electrode active layer, wherein the material of the negative electrode active layer comprises a negative electrode active material, a first conductive agent, a second conductive agent and a binder; the conductivity of the first conductive agent is 500S/m-2000S/m, and the conductivity of the second conductive agent is 10 5 S/m-10 8 S/m; wherein the mass percentage of the first conductive agent in the anode active layer is 10% -50%, and the mass percentage of the second conductive agent in the anode active layer is 0.3% -0.6%.
  2. 2. The negative electrode sheet according to claim 1, wherein the particle size of the first conductive agent is 30nm to 5 μm and the particle size of the second conductive agent is 20nm to 200nm.
  3. 3. The negative electrode sheet according to claim 1, wherein the first conductive agent includes at least one of graphite, super P, and acetylene black; and/or the second conductive agent includes at least one of graphene, carbon nanotubes, and carbon fibers.
  4. 4. The negative electrode sheet according to claim 1, wherein the mass percentage of the first conductive agent in the negative electrode active layer is 40% to 50%.
  5. 5. The negative electrode sheet according to claim 1, wherein the mass percentage of the negative electrode active material in the negative electrode active layer is 44.4% to 58.7%; and/or the mass percentage of the binder in the anode active layer is 1-5%.
  6. 6. The negative electrode sheet according to claim 1, wherein the negative electrode active material includes at least one of elemental silicon, a silicon-carbon material, a silicon oxygen material, and a silicon-based alloy material; and/or the binder comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber and polyacrylic acid.
  7. 7. The negative electrode sheet according to any one of claims 1 to 6, wherein the thickness of the negative electrode active layer is 370 μm to 420 μm.
  8. 8. The preparation method of the negative plate is characterized by comprising the following steps: Providing a negative electrode active material, a first conductive agent, a second conductive agent, and a binder; mixing the first conductive agent and the second conductive agent to obtain a composite conductive agent; Mixing the negative electrode active material, the binder and the composite conductive agent to obtain a mixed dry material; and forming a negative electrode active layer by adopting a dry film forming process to the mixed dry material to obtain a negative electrode plate.
  9. 9. The method for preparing a negative electrode sheet according to claim 8, wherein the mixing the first conductive agent and the second conductive agent to obtain a composite conductive agent comprises: Mixing part of the first conductive agent with part of the second conductive agent to obtain a first mixture; mixing the rest of the first conductive agent with the first mixture to obtain a second mixture; mixing the rest of the second conductive agent with the second mixture to obtain the composite conductive agent.
  10. 10. The method for preparing a negative electrode sheet according to claim 8, wherein the forming the negative electrode active layer from the mixed dry material by a dry film forming process comprises: Shearing the mixed dry material to form sheared mixed dry material; And pressing the shearing mixed dry material into a film at the temperature of 80-120 ℃ to form the anode active layer.
  11. 11. A battery comprising the negative electrode sheet according to any one of claims 1 to 7, or comprising the negative electrode sheet produced by the production method of the negative electrode sheet according to any one of claims 8 to 10.
  12. 12. The battery of claim 11, further comprising a positive electrode sheet comprising a positive electrode active material having a molecular formula of Li 1+x Co y Mn 2-(x+y) O 4 , 0< x +.0.33, 0< y +.0.1.

Description

Negative plate, preparation method thereof and battery Technical Field The application relates to the technical field of batteries, in particular to a negative plate, a preparation method thereof and a battery. Background In the field of batteries, the performance of a negative electrode sheet, which is a critical part of a battery, directly affects the overall performance of the battery. With the continuous expansion of battery application scenes and the increasing of battery performance, the thickness of the negative plate is increased, thereby providing assistance for improving the capacity and energy density of the battery. But since ions need to be transported in the negative electrode sheet during charge and discharge of the battery to achieve transfer and storage of charge. For the negative plate with larger thickness, the transmission path of electrons in the negative plate is prolonged, so that the resistance applied to the electrons in the transmission process is increased, mass transfer is easy to occur, the capacity exertion rate of the negative plate is lower, and the performance improvement of the battery is seriously influenced. Disclosure of Invention The application provides a negative plate, a preparation method thereof and a battery, wherein a three-dimensional conductive network can be constructed through the synergistic effect of a first conductive agent and a second conductive agent, so that the electron transmission efficiency is remarkably improved, the capacity exertion rate is ensured, and the circulation stability is improved. In a first aspect, the present application provides a negative electrode sheet including a negative electrode active layer, the material of the negative electrode active layer including a negative electrode active material, a first conductive agent, a second conductive agent, and a binder; the conductivity of the first conductive agent is 500S/m-2000S/m, and the conductivity of the second conductive agent is 10 5S/m-108 S/m; Wherein, the mass percent of the first conductive agent in the anode active layer is 10% -50%, and the mass percent of the second conductive agent in the anode active layer is 0.3% -0.6%. By including the first conductive agent and the second conductive agent in the anode active layer of the anode sheet, a three-dimensional conductive network can be formed by matching with the anode active material and the binder, and an electron transmission channel is increased. The first conductive agent has moderate conductivity and higher addition proportion, can be fully contacted with the negative electrode active material, reduces interface resistance, has better dispersion performance, has higher conductivity, can build a conductive bridge crossing particles, forms a three-dimensional conductive network, obviously reduces the internal resistance of the negative electrode sheet, and improves capacity exertion rate. The first conductive agent and the second conductive agent can form a 'short-range + long-range' cooperative conductive network in cooperation, so that electron transmission optimization is realized. In addition, the first conductive agent and the second conductive agent can also form a framework in the negative electrode plate, so that pulverization of the negative electrode active material can be reduced, and the mechanical property of the negative electrode plate is improved. Namely, the negative electrode sheet provided by the embodiment of the application can construct a three-dimensional conductive network through the synergistic effect of the first conductive agent and the second conductive agent, so that the electron transmission efficiency is obviously improved, the capacity exertion rate is ensured, the circulation stability is improved, and the mechanical property is improved. Alternatively, the particle size of the first conductive agent is 30nm to 5 μm and the particle size of the second conductive agent is 20nm to 200nm. By making the particle diameters of the first conductive agent and the second conductive agent respectively in the above ranges, the first conductive agent can form a short-range conductive network between the anode active materials, thereby ensuring rapid transmission of electrons between the anode active materials, and the second conductive agent builds a bridge of length Cheng Daodian in the gap of the first conductive agent, shortening the electron transmission path. In addition, the first conductive agent can wrap the anode active material and reserve gaps, can relieve the expansion stress of the anode active material, and the second conductive agent can support the gap structure to prevent the structure from collapsing, so that the mechanical property of the anode plate is improved under the synergistic effect of the first conductive agent and the second conductive agent. Optionally, the first conductive agent includes at least one of graphite, super P, and acetylene black; and/or the second conduct