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CN-122025532-A - Negative plate, preparation method thereof and battery

CN122025532ACN 122025532 ACN122025532 ACN 122025532ACN-122025532-A

Abstract

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 current collector and a negative electrode active layer, and the negative electrode active layer is arranged on at least one side of the negative electrode current collector; the passivation layer is arranged on one side, away from the negative electrode current collector, of the negative electrode active layer, the passivation layer comprises a composite lithium-containing compound and a composite conductive adhesive, the composite conductive adhesive comprises a conductive core layer and a coating layer, the conductive core layer comprises a conductive carbon substrate, the coating layer comprises a conductive polymer layer and an adhesive layer, the conductive polymer layer is coated on the surface of the conductive core layer, and the adhesive layer is grafted on one side, away from the conductive core layer, of the conductive polymer layer. The composite conductive adhesive with integrated design of conductivity and cohesiveness can improve the ion transmission efficiency and the electron transmission efficiency of the passivation layer, thereby effectively reducing the internal resistance of the battery, and the composite conductive adhesive can enable the passivation layer to be combined with the negative electrode active material layer more tightly, reduce interface impedance and improve the performance of the battery.

Inventors

  • Kuang Kunbin
  • HONG SIFAN
  • LIU RONGJIANG
  • WU YONGXUAN

Assignees

  • 惠州亿纬锂能股份有限公司

Dates

Publication Date
20260512
Application Date
20260130

Claims (11)

  1. 1. A negative electrode sheet (100), comprising: A negative electrode current collector (10), A negative electrode active layer (20), the negative electrode active layer (20) being provided on at least one side of the negative electrode current collector (10), and A passivation layer (30), wherein the passivation layer (30) is arranged on the surface of one side of the negative electrode active layer (20) facing away from the negative electrode current collector (10), and the passivation layer (30) comprises a compound containing lithium and a compound conductive adhesive; The composite conductive adhesive comprises a conductive core layer and a coating layer, wherein the conductive core layer comprises a conductive carbon substrate, the coating layer comprises a conductive polymer layer and an adhesive layer, the conductive polymer layer is coated on the surface of the conductive core layer, and the adhesive layer is grafted on the surface of one side, away from the conductive core layer, of the conductive polymer layer.
  2. 2. The negative electrode sheet (100) according to claim 1, wherein the composite lithium-containing compound includes a first lithium-containing compound including at least one of lithium hexafluorophosphate, lithium difluorosulfonimide, and lithium difluorooxalato borate and a second lithium-containing compound including at least one of lithium carbonate, lithium nitrate, and lithium hydroxide.
  3. 3. The negative electrode sheet (100) according to claim 1 or 2, wherein the mass percentage of the composite conductive binder and the composite lithium-containing compound is 80% -90%, 10% -20%.
  4. 4. The negative electrode sheet (100) according to claim 2, wherein a mass ratio of the first lithium-containing compound to the second lithium-containing compound is 1 to 2:1 to 2.
  5. 5. The negative electrode sheet (100) according to any one of claims 1 to 4, wherein the mass ratio of the conductive core layer, the conductive polymer layer, and the adhesive layer in the composite conductive adhesive is 0.5 to 1.5:2.5 to 3.5:4.5 to 5.5.
  6. 6. The negative electrode sheet (100) according to any one of claims 1 to 5, wherein the passivation layer (30) has a thickness of 2 μm to 3 μm.
  7. 7. The negative electrode sheet (100) according to any one of claims 1 to 6, wherein the conductive carbon base material comprises at least one of carbon black, graphene, and carbon nanotubes, and/or, The material of the conductive polymer layer comprises at least one of polyaniline, polyacetylene, polypyrrole and polythiophene, and/or, The material of the adhesive layer comprises at least one of polyacrylic acid, polyacrylonitrile, styrene butadiene, sodium polyacrylate, lithium polyacrylate, potassium polyacrylate, calcium polyacrylate, magnesium polyacrylate, rubidium polyacrylate, cesium polyacrylate, francium polyacrylate, barium polyacrylate, strontium polyacrylate, lithium carboxymethyl cellulose, beryllium carboxymethyl cellulose and sodium carboxymethyl cellulose.
  8. 8. A method of producing the negative electrode sheet (100) according to any one of claims 1 to 7, comprising: Providing a negative electrode current collector (10); Providing a negative electrode slurry, coating the negative electrode slurry on the negative electrode current collector (10), and drying to form a negative electrode active layer (20); Preparing passivation layer slurry containing a composite lithium-containing compound and a composite conductive binder, coating the passivation layer slurry on the surface of one side of the negative electrode active layer (20) away from the negative electrode current collector (10), drying, and forming a passivation layer (30) on the surface of the negative electrode active layer (20).
  9. 9. The method of producing a negative electrode sheet (100) according to claim 8, characterized in that the method of producing the composite conductive adhesive comprises: dispersing the conductive core layer in acid liquor, adding conductive polymer monomer and first solvent, and dispersing to obtain first solution; adding an oxidant into the first solution, reacting to polymerize the conductive polymer monomer, and forming a conductive polymer layer on the surface of the conductive core layer to obtain an intermediate; Dispersing the intermediate and the passivation layer binder in a second solvent to form a second solution; dispersing a free radical initiator in a third solvent to form a third solution; and adding the third solution into the second solution, and reacting to enable the surface of the conductive polymer layer to be grafted with the adhesive layer, so as to obtain the slurry containing the composite conductive adhesive.
  10. 10. The method of producing a negative electrode sheet (100) according to claim 8 or 9, wherein the passivation layer slurry has a solid content of 20% -25%.
  11. 11. A battery, characterized by comprising the negative electrode sheet (100) according to any one of claims 1 to 7 or the negative electrode sheet (100) produced by the production method of the negative electrode sheet (100) according to any one of claims 8 to 10; the battery also comprises a positive plate and a diaphragm; Wherein, the diaphragm set up in negative pole piece (100) with between the positive pole piece, passivation layer (30) set up in negative pole piece (100) be close to diaphragm one side.

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 At present, the lithium ion battery is widely applied to the fields of new energy automobiles and electronic products, and the negative electrode of the lithium ion battery is a key factor affecting the performance of the lithium ion battery. In the first charging process, the lithium ion battery can form an SEI film on the surface of the negative electrode, and the SEI film can prevent the negative electrode from being directly contacted with electrolyte, so that side reactions of the battery are reduced, and the performance of the battery is improved. However, when the negative electrode material is graphite, the graphite is a typical intercalation negative electrode material, and graphite particles repeatedly expand and contract during the continuous charge and discharge of the battery, resulting in rupture of the SEI film, thereby reducing the cycling stability of the lithium ion battery. In the related art, the interface protection layer is arranged on the surface of the anode active material layer, so that the cycle stability of the battery is improved. However, the interface protective layer has poor conductivity and stability, thereby affecting the performance of the negative electrode sheet and the battery. Disclosure of Invention The application provides a negative plate, a preparation method thereof and a battery, and aims to solve the problem of poor battery performance caused by poor conductivity and stability of the conventional interface protection layer. In a first aspect, the present application provides a negative electrode sheet comprising: A negative electrode current collector, a negative electrode, A negative electrode active layer disposed on at least one side of the negative electrode current collector, and The passivation layer is arranged on the surface of one side, away from the negative electrode current collector, of the negative electrode active layer, and comprises a compound lithium-containing compound and a compound conductive adhesive; the composite conductive adhesive comprises a conductive core layer and a coating layer, wherein the conductive core layer comprises a conductive carbon substrate, the coating layer comprises a conductive polymer layer and an adhesive layer, the conductive polymer layer is coated on the surface of the conductive core layer, and the adhesive layer is grafted on the surface of one side of the conductive polymer layer, which is away from the conductive core layer. According to the application, the passivation layer is arranged on the surface of the anode active layer, and comprises the composite lithium-containing compound and the composite conductive adhesive, so that the composite lithium-containing compound and the composite conductive adhesive of the passivation layer are highly dispersed and more uniformly dispersed, a uniform and compact ion transmission channel and an electron transmission channel are constructed in the passivation layer, the ion transmission efficiency and the electron transmission efficiency are improved, the battery has lower interface impedance, the internal resistance of the battery is effectively reduced, the multiplying power performance and the cycle performance of the battery are improved, and meanwhile, the composite conductive adhesive can enable the combination of the passivation layer and the anode active material layer to be tighter, the interface impedance is further reduced, and the multiplying power performance of the battery is improved. The composite conductive adhesive comprises the conductive core layer and the coating layer, wherein the conductive core layer comprises a conductive carbon substrate, the conductive carbon substrate provides electronic conductivity for the composite conductive adhesive, the coating layer comprises a conductive polymer layer and an adhesive layer grafted on the surface of the conductive polymer layer, a tightly connected electronic transmission network can be formed between the conductive polymer layer and the conductive carbon substrate, the conductive polymer layer can be strongly connected with the adhesive layer, and stable conductivity and adhesive performance are provided for the composite conductive adhesive. Alternatively, the composite lithium-containing compound includes a first lithium-containing compound including at least one of lithium hexafluorophosphate, lithium difluorosulfonimide, and lithium difluorooxalato borate, and a second lithium-containing compound including at least one of lithium carbonate, lithium nitrate, and lithium hydroxide. The first lithium-containing compound can hydrolyze or dissociate to form lithium fluoride, so that the SEI film formed by induction in the first formation process of the battery contains lithium flu