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CN-122025652-A - Composite current collector, preparation method and negative plate

CN122025652ACN 122025652 ACN122025652 ACN 122025652ACN-122025652-A

Abstract

The invention provides a composite current collector, a preparation method and a negative plate, which comprise a porous copper substrate layer, a composite doping layer, a conducting layer and a lithium-philic modification layer, wherein the composite doping layer comprises a rare earth element doped copper layer, the composite doping layer is arranged on the pore surface of the porous copper substrate layer, the conducting layer is arranged on the surface of the composite doping layer, and the lithium-philic modification layer is formed on one surface of the conducting layer, which is far away from the composite doping layer. The porous copper substrate layer can provide a buffer space for volume expansion of a silicon-carbon negative electrode, a compound containing rare earth elements in the composite doped layer can improve the mechanical strength and conductivity of the current collector through lattice distortion optimization, provide structural support for expansion constraint, reduce electron transmission resistance, enable a composite conductive material of the conductive layer to form a high-speed conductive channel, improve electron and lithium ion migration efficiency, enable a lithium-philic modification layer to conduct uniform deposition of lithium ions, and therefore the composite current collector can effectively inhibit expansion of the current collector and synchronously optimize conductivity and circulation stability.

Inventors

  • JIANG BING
  • LIU GUANXIN
  • LIAO XINGQUN

Assignees

  • 深圳市豪鹏科技股份有限公司

Dates

Publication Date
20260512
Application Date
20260130

Claims (19)

  1. 1. The composite current collector is characterized by comprising a porous copper substrate layer, a composite doping layer, a conducting layer and a lithium-philic modification layer, wherein the composite doping layer comprises a copper layer doped with rare earth elements, the composite doping layer is arranged on the surface of a pore of the porous copper substrate layer, the conducting layer is arranged on the surface of the composite doping layer, and the lithium-philic modification layer is formed on one surface of the conducting layer, which is away from the composite doping layer.
  2. 2. The composite current collector of claim 1, wherein the porosity of the porous copper substrate layer decreases gradually along the interior of the porous copper substrate layer toward the surface of the porous copper substrate layer, the porosity of the porous copper substrate layer being 40-60%.
  3. 3. The composite current collector of claim 2, wherein the porous copper substrate layer has an internal pore size of 10-30 μm and a surface pore size of 1-3 μm.
  4. 4. The composite current collector of claim 1 wherein said porous copper substrate layer has a plurality of interconnected spherical pores.
  5. 5. The composite current collector of claim 1, wherein the porous copper substrate layer has a pore wall thickness of 1-3 μm; the thickness of the porous copper substrate layer is 30-40 mu m.
  6. 6. The composite current collector according to claim 1, wherein the doping amount of the rare earth element is 0.05 to 0.2wt% based on 100% of the total mass of the porous copper base layer and the composite doping layer.
  7. 7. The composite current collector of claim 1 wherein said conductive layer comprises a composite of carbon nanotubes and graphene, said carbon nanotubes grown vertically on a surface of a composite doped layer, and wherein sheets of said graphene are positioned vertically to an axial position of said carbon nanotubes; The vertical orientation degree of the carbon nano tube in the conductive layer is more than or equal to 90%; the network density of the carbon nano tubes in the conductive layer is 10 10 ~10 12 roots/cm 2 .
  8. 8. The composite current collector of claim 1, wherein the conductive layer has a thickness of 50-200 nm.
  9. 9. The composite current collector of claim 7, wherein the diameter of the carbon nanotubes is 10-30 nm, and the thickness of the graphene sheets is 1-3 nm; The mass ratio of the carbon nano tube to the graphene is 1:1-3:1.
  10. 10. The composite current collector of claim 1 wherein said lithium-philic modifying layer comprises a lithium-philic species comprising one or more of the species comprising elemental silver, zinc, tin, bismuth, and/or, The rare earth element-containing compound comprises one or more of lanthanum nitrate and cerium nitrate; The copper content in the porous copper basal layer is more than or equal to 99.9 percent.
  11. 11. The composite current collector according to claim 1, wherein the total thickness of the composite current collector is 6-30 μm; The thickness of the composite doping layer is 1-10 mu m, and the thickness of the lithium-philic modification layer is 5-20 nm.
  12. 12. The method for preparing a composite current collector according to any one of claims 1 to 11, comprising the operations of: Mixing a copper material with a pore-forming agent, sintering in a hydrogen atmosphere after cold press molding, and removing the pore-forming agent to obtain a porous copper substrate layer; preparing a compound containing rare earth elements into a mixed solution, and placing a porous copper substrate layer in the mixed solution for electroplating to form a composite doping layer to obtain a first precursor; Obtaining a composite conductive material; depositing a composite conductive material on the surface of the first precursor through chemical vapor deposition to obtain a second precursor; Preparing a lithium-philic substance into a solution, and then placing a second precursor into the solution, and under the condition of thermal reaction, forming a lithium-philic modification layer on the surface of the second precursor.
  13. 13. The method for preparing a composite current collector according to claim 12, wherein in the operation of preparing the porous copper base layer, the cold pressing pressure is 100-200 mpa, and the cold pressing pressure gradually decreases from the surface of the porous copper base layer to the inside of the porous copper base layer; The sintering temperature is 900-1000 ℃ and the sintering time is 3-5 h.
  14. 14. The method for preparing a composite current collector according to claim 12, wherein the operation of plating the mixed solution on the surface of the porous copper substrate layer is electroplating, wherein in the electroplating operation, the current density is 2-5 a/dm 2 , the temperature is 40-60 ℃, the pH value is 1-2, and the electroplating time is 30-60 min.
  15. 15. The method of preparing a composite current collector according to claim 12, wherein the pore-forming agent comprises one or more of ammonium carbonate and ammonium bicarbonate; The particle size of the pore-forming agent is 1-50 mu m.
  16. 16. The method for preparing a composite current collector according to claim 12, wherein the high temperature is 30 to 60 ℃ in the operation of forming the lithium-philic modification layer.
  17. 17. The method of manufacturing a composite current collector according to claim 12, wherein the composite conductive material is manufactured by: methane and ethylene are used as carbon sources to be introduced into a reaction chamber, hydrogen is introduced, and the composite conductive material is formed under the conditions of a catalyst and high temperature.
  18. 18. The method for preparing a composite current collector according to claim 17, wherein the catalyst comprises iron-cobalt mixed metal nanoparticles, and the particle size of the iron-cobalt mixed metal nanoparticles is 5-10 nm; The content of the catalyst is 0.1-0.3wt%; In the high-temperature condition, the treatment temperature is 750-850 ℃ and the treatment time is 1-2 h.
  19. 19. A negative electrode sheet, characterized by comprising the composite current collector according to any one of claims 1 to 11, or the composite current collector produced by the production method of the composite current collector according to any one of claims 12 to 18.

Description

Composite current collector, preparation method and negative plate Technical Field The invention relates to the technical field of batteries, in particular to a composite current collector, a preparation method and a negative plate. Background As lithium ion batteries are widely applied to application fields of new energy automobiles, energy storage systems and the like, the comprehensive requirements of the market on the battery of high energy density, quick charge performance and long cycle life are continuously improved, the comprehensive requirements of the new energy automobiles and the energy storage systems on the battery of high energy density, quick charge and long cycle life are adapted, and particularly the huge expansion challenges brought by high-capacity materials (the specific capacity of the materials is 10 times of that of graphite) such as silicon-carbon cathodes and the like are met, and the modification operation is carried out on a negative current collector copper foil in the prior art; the prior art aims at the modification scheme of the copper foil mainly comprises an active material expansion inhibition or interface electrochemical reaction kinetics promotion, specifically, the copper foil adopts a composite current collector scheme, adopts a composite structure of a polymer substrate and a copper layer, relies on the flexibility of a light polymer layer to buffer the volume expansion of an active material, adopts a surface roughening scheme, increases the surface roughness of the copper foil through mechanical polishing, electrochemical corrosion and other processes, strengthens the interface bonding strength with the active material and reduces the contact resistance, adopts an alloying modification scheme, dopes alloy elements such as Zn, al, sn and the like in the copper, improves the mechanical strength and the ductility of the copper foil by virtue of a smelting or electroplating process so as to restrain the deformation of an electrode structure, adopts a carbon layer cladding scheme, coats amorphous carbon or randomly distributed carbon nano tubes on the surface of the copper foil so as to promote the conductivity of the current collector, however, the modification scheme has the problems that the expansion inhibition and the dynamic promotion cannot be realized, and is difficult to synchronously meet the comprehensive performance requirements of high energy density, quick charge and long cycle of a battery, especially when matching with high specific capacity negative electrode materials such as silicon carbon, because the volume expansion rate of the silicon-carbon negative electrode is far higher than that of the traditional graphite negative electrode, the existing copper foil modification scheme can not effectively relieve the problems of volume deformation and interface impedance increase of the electrode, so that the cycle stability of the battery is rapidly attenuated. Disclosure of Invention Aiming at the problem that the prior art cannot simultaneously inhibit the volume expansion and the lifting dynamics of the negative electrode current collector, the composite current collector, the preparation method and the negative electrode plate are provided. The technical scheme adopted by the invention for solving the technical problems is as follows: In one aspect, the invention provides a composite current collector, which comprises a porous copper substrate layer, a composite doping layer, a conductive layer and a lithium-philic modification layer, wherein the composite doping layer comprises a copper layer doped with rare earth elements, the composite doping layer is arranged on the pore surface of the porous copper substrate layer, the conductive layer is arranged on the surface of the composite doping layer, and the lithium-philic modification layer is formed on one surface of the conductive layer, which is far away from the composite doping layer. Optionally, the porosity of the porous copper substrate layer gradually decreases from the inside of the porous copper substrate layer to the surface of the porous copper substrate layer, and the porosity of the porous copper substrate layer is 40-60%. Optionally, the inner aperture of the porous copper substrate layer is 10-30 μm, and the surface aperture of the porous copper substrate layer is 1-3 μm. Optionally, the porous copper base layer has a plurality of interconnected spherical pores. Optionally, the thickness of the hole wall of the porous copper substrate layer is 1-3 mu m; the thickness of the porous copper substrate layer is 30-40 mu m. Optionally, the doping amount of the rare earth element is 0.05-0.2wt% based on 100% of the total mass of the porous copper base layer and the composite doping layer. Optionally, the conductive layer comprises a composite of carbon nanotubes and graphene, wherein the carbon nanotubes are vertically grown on the surface of the composite doped layer, and the lamellar layers of t