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CN-122025665-A - Metal foil used as battery current collector and surface treatment method thereof

CN122025665ACN 122025665 ACN122025665 ACN 122025665ACN-122025665-A

Abstract

The invention relates to the technical field of battery materials, in particular to a metal foil used as a battery current collector and a surface treatment method thereof, wherein one side surface of the metal foil is provided with pits, the pits form protruding points on the other side surface of the metal foil, when the side surface which is visually the pits is taken as a test reference surface, the depth range of the pits is 7-33 mu m, the diameter range of holes of the pits is 29-178 mu m, and the density range of the pits is 5-14 holes/mm 2 . The metal foil and the surface treatment method thereof provided by the invention enable the metal foil to have high elongation and high tensile strength at the same time, and have high binding force with active materials when being used as a current collector of a lithium battery.

Inventors

  • Xu Chunzi
  • YAN XING
  • Fu dongxing
  • WU JING
  • WANG HUI

Assignees

  • 重庆硕盈峰新材料科技有限公司

Dates

Publication Date
20260512
Application Date
20231229

Claims (10)

  1. 1. A metal foil for use as a current collector of a battery, characterized in that one side of the metal foil has pits forming bumps on the other side of the metal foil, when the side that is visually pits is taken as a test reference surface: the depth range of the pits is 7-33 mu m; the hole diameter range of the pits is 29-178 mu m; The density range of the pits is 5-14 pits/mm 2 .
  2. 2. A metal foil as claimed in claim 1, wherein, The depth range of the pits is 7-24 mu m; The hole diameter range of the pits is 29-126 mu m; The density range of the pits is 8-14 pits/mm 2 .
  3. 3. A metal foil as claimed in claim 2, wherein, The depth range of the pits is 7-16 mu m; the pit diameter range is 29-56 mu m; the density range of the pits is 8-12 pits/mm 2 .
  4. 4. A metal foil according to any one of claims 1 to 3, wherein the inner surfaces of the pits of the metal foil are attached with a cured silane coupling agent.
  5. 5. A surface treatment method of a metal foil used as a battery current collector is characterized in that shot blasting is carried out on the surface of the metal foil, one side surface of the treated metal foil is provided with pits, the pits form convex points on the other side surface of the metal foil, and when the side surface which is visually pits is taken as a test reference surface: the depth range of the pits is 7-33 mu m; The hole diameter range of the pits is 29-140 mu m; The density range of the pits is 8-14 pits/mm 2 .
  6. 6. The surface treatment method according to claim 5, wherein uncured silane coupling agent is attached to the surface of the beads for striking the metal foil.
  7. 7. The method according to claim 6, wherein the silane coupling agent is gamma-methacryloxypropyl trimethoxysilane.
  8. 8. The metal foil according to any one of claims 1 to 4, wherein the metal foil is copper foil or aluminum foil.
  9. 9. A battery pole piece comprising a current collector and a coating attached to the surface of the current collector, wherein the current collector is the metal foil of any one of claims 1-4.
  10. 10. A battery comprising the pole piece of claim 9.

Description

Metal foil used as battery current collector and surface treatment method thereof Technical Field The invention relates to the technical field of battery materials, in particular to a metal foil used as a battery current collector and a surface treatment method thereof. Background The secondary battery is composed of positive/negative battery pole piece, electrolyte and diaphragm, the battery pole piece is composed of current collector and active material coating attached to the current collector. In the process of preparing the battery pole piece and assembling the battery pole piece into a battery, the pole piece needs to be subjected to procedures such as rolling, winding and the like, and the active substances are embedded and released in the process of charging and discharging the battery. Therefore, the stability of the battery pole piece structure can be challenged both during the manufacturing process and during the use process of the battery pole piece. Maintaining the structural stability of the battery pole piece mainly depends on two aspects, namely the ductility and the tensile strength of the current collector, and the cohesive force between the current collector and the active substance. The binding force between the current collector and the active material is mainly provided by the binder, and in order to enhance the effect of the binder, the related art has improved the binder from various angles, for example, the invention patent application with the application number of CN2023112327634 forms a three-dimensional network structure by grafting acrylic acid and styrenesulfonic acid on the side chain of the conventional carboxymethyl cellulose and introducing a polyfunctional crosslinking monomer, thereby remarkably enhancing the mechanical strength of the binder itself. But it is desired to more comprehensively and effectively improve the structural stability of the battery pole piece, and it is also desired to further improve the adhesive force between the adhesive and the interface of the current collector, the adhesive force between the adhesive and the active material, and the mechanical properties of the current collector itself. In some related art, by changing the surface roughness of the metal foil, the contact area between the electrode paste and the current collector is increased, thereby improving the adhesion. The method for changing the surface roughness of the metal foil is mainly divided into a chemical treatment method and a physical treatment method, wherein the chemical treatment method mainly comprises deposition and etching, other metal elements are inevitably caused to enter the copper foil in the treatment process, the copper foil has poor oxidation resistance, and the copper foil is electrochemically corroded in the use process of the lithium battery, so that the better use effect of the lithium battery cannot be realized. The physical treatment method is mainly friction or roll pressing, and the treatment method can cause the reduction of the tensile strength and the elongation of the copper foil. Disclosure of Invention A first aspect of the present invention is directed to a metal foil having both high elongation and high tensile strength, and having high adhesion between the metal foil and an active material when used as a current collector for a lithium battery. The metal foil used as the battery current collector is characterized in that one side surface of the metal foil is provided with pits, the pits form protruding points on the other side surface of the metal foil, when the side surface which is visually pits is taken as a test reference surface, the depth range of the pits is 7-33 mu m, the hole diameter range of the pits is 29-178 mu m, and the density range of the pits is 5-14 pits/mm 2. Preferably, the depth of the pits is 7-24 μm, the hole diameter of the pits is 29-126 μm, and the density of the pits is 8-14 pits/mm 2. Further preferably, the depth of the pits is 7-16 μm, the hole diameter of the pits is 29-56 μm, and the density of the pits is 8-12 pits/mm 2. Further preferably, the inner side surfaces of the pits of the metal foil are attached with a cured silane coupling agent. A second aspect of the present invention is to provide a surface treatment method of a metal foil used as a current collector of a battery, wherein a surface of the metal foil is shot-blasted, pits are formed on one side surface of the treated metal foil, the pits form a bump on the other side surface of the metal foil, when a side surface which is visually pits is taken as a test reference surface, the depth of the pits is 7-33 μm, the hole diameter of the pits is 29-140 μm, and the density of the pits is 8-14 pits/mm 2. Preferably, the surface of the beads for striking the metal foil is attached with an uncured silane coupling agent. Preferably, the silane coupling agent is gamma-methacryloxypropyl trimethoxysilane. In some possible embodiments, the metal foil is copper fo