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US-12624201-B2 - Binder composition, secondary battery, battery module, battery pack and power consuming device

US12624201B2US 12624201 B2US12624201 B2US 12624201B2US-12624201-B2

Abstract

Provided are a binder composition, an electrode, a battery and a power consuming device. The binder composition comprises a fluoropolymer A and a copolymer B, wherein the copolymer B comprises a structural unit derived from a monomer containing a cyano group and a structural unit derived from a monomer containing an ester group. The binder of the present application has a strong bonding force, and the cycling performance of the secondary battery comprising same is excellent.

Inventors

  • Lianwei DUAN
  • Huihui Liu
  • Cheng Li
  • Wei Feng

Assignees

  • CONTEMPORARY AMPEREX TECHNOLOGY (HONG KONG) LIMITED

Dates

Publication Date
20260512
Application Date
20231121

Claims (17)

  1. 1 . A binder composition, comprising a fluoropolymer A and a copolymer B, wherein the copolymer B comprises a structural unit derived from a monomer containing a cyano group and a structural unit derived from a monomer containing an ester group, a mass ratio of the structural unit derived from the monomer containing the cyano group to the structural unit derived from the monomer containing the ester group in the copolymer B is 8:1 to 12:1, based on a total mass of the copolymer B, wherein the copolymer B further comprises a structural unit derived from the monomer containing the group shown in formula I, in which, n is selected from 0, 1, 2, or 3, and wherein a mass content of the structural unit derived from the monomer containing a group shown in formula I is 0.1%-1.5%, based on a total mass of the copolymer B, wherein the monomer containing the cyano group is acrylonitrile, the monomer containing the ester group is isooctyl acrylate, the monomer containing the group shown in formula I is N-allyl-2-pyrrolidone.
  2. 2 . The binder composition according to claim 1 , wherein a weight average molecular weight of the fluoropolymer A is 600,000-900,000 g/mol, and a weight average molecular weight of the copolymer B is 400,000-700,000 g/mol.
  3. 3 . The binder composition according to claim 1 , wherein a mass ratio of the fluoropolymer A to the copolymer Bis 1:4-4:1.
  4. 4 . The binder composition according to claim 1 , wherein the fluoropolymer A is selected from one or more of polyvinylidene fluoride, and the copolymers thereof with tetrafluoroethylene, hexafluoropropylene, and trichloroethylene.
  5. 5 . The binder composition according to claim 1 , wherein the monomer containing the cyano group is selected from one or more of acrylonitrile, methacrylonitrile, halogenated acrylonitrile, and methoxyacrylonitrile.
  6. 6 . The binder composition according to claim 1 , wherein the monomer containing the ester group is selected from one or more of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isoamyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate.
  7. 7 . The binder composition according to claim 1 , wherein the mass ratio of the structural unit derived from the monomer containing the cyano group to the structural unit derived from the monomer containing the ester group in the copolymer B is 8:1-10:1.
  8. 8 . The binder composition according to claim 7 , wherein the monomer containing the group shown in formula I is selected from one or more of N-vinylpyrrolidone and N-allyl-2-pyrrolidone.
  9. 9 . The binder composition according to claim 1 , wherein the mass content of the structural unit derived from the monomer containing the group shown in formula I is 0.5%-1.0%, based on the total mass of the copolymer B.
  10. 10 . The binder composition of claim 1 , wherein, based on a total mass of the copolymer B, a mass content of the structural unit derived from the monomer containing the cyano group is from 80% to 95%, a mass content of the structural unit derived from the monomer containing the ester group is from 8% to 12%, a mass content of the structural unit derived from the monomer containing the group shown in formula I is from 0.5% to 1.5%.
  11. 11 . The binder composition of claim 1 , wherein the fluoropolymer A is polyvinylidene fluoride (PVDF) having a particle size Dv50 of 5 μm to 10 μm, a crystallinity of 35-40%, and a melting point from 160° C. to 170° C.
  12. 12 . A secondary battery, comprising an electrode assembly and an electrolyte solution, wherein the electrode assembly includes a positive electrode plate, a separator and a negative electrode plate, and the positive electrode plate comprises a positive electrode active material and the binder according to claim 1 .
  13. 13 . The secondary battery according to claim 12 , wherein the positive electrode active material is a lithium-containing transition metal oxide, a doped and modified material of the lithium-containing transition metal oxide, a conductive carbon-coated modified material of the lithium-containing transition metal oxide, a conductive metal-coated modified material of the lithium-containing transition metal oxide, or a conductive polymer-coated modified material of the lithium-containing transition metal oxide.
  14. 14 . A battery module, comprising the secondary battery according to claim 12 .
  15. 15 . A battery pack, comprising the battery module according to claim 14 .
  16. 16 . A power consuming device, comprising the secondary battery according to claim 12 .
  17. 17 . A power consuming device, comprising the battery module according to claim 14 .

Description

CROSS REFERENCE TO RELATED MATTER This application is a continuation of international application PCT/CN2022/096409, filed May 31, 2022 and entitled “BINDER COMPOSITION, SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK AND POWER CONSUMING DEVICE”, the entire content of which is hereby incorporated by reference in its entirety. TECHNICAL FIELD The present application relates to the technical field of lithium batteries, and in particular to a binder composition, a secondary battery, a battery module, a battery pack and a power consuming device. BACKGROUND ART In recent years, lithium ion batteries have been widely used in energy storage power systems such as hydroelectric, thermal, wind and solar power plants, as well as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields. With the popularity of lithium ion battery applications, there are higher requirements on their performance and cost. Binders are materials that are commonly used in lithium ion batteries, and are in great demand in electrode plates, separators, and packaging and the like of batteries. However, the existing binder has high cost and poor bonding performance, thereby increasing the cost of the battery and reducing the cycling performance of the battery. Therefore, the existing binder still needs to be improved. SUMMARY OF THE INVENTION The present application has been made in view of the above problems, and an objective thereof is to provide a binder composition which can reduce the cost of the binder and has excellent bonding properties. A first aspect of the present application provides a binder composition, which comprises a fluoropolymer A and a copolymer B, wherein the copolymer B comprises a structural unit derived from a monomer containing a cyano group and a structural unit derived from a monomer containing an ester group. Thus, in the present application, the fluoropolymer A and the copolymer B comprising a structural unit derived from a monomer containing a cyano group and a structural unit derived from a monomer containing an ester group are used together as a binder; compared to the fluoropolymer A or the copolymer B alone used as a binder, the bonding performance of the binder and the cycling performance of the battery can be further improved. In any embodiment, the weight average molecular weight of the fluoropolymer A is 600,000-900,000, and the weight average molecular weight of the copolymer B is 400,000-700,000. The control of the weight average molecular weight of the polymer can balance the bonding performance and processability of the binder. If the weight average molecular weight of the polymer is too low, the brittleness will be too high, such that the bonding force of the binder is insufficient. If the weight average molecular weight of the polymer is too high, it will be difficult to disperse an electrode active material. Moreover, the reasonable combination of polymers with different molecular weights can improve the dispersion of the electrode active material, thereby improving the performance of the battery. In any embodiment, the mass ratio the fluoropolymer A to the copolymer B is 1:4-4:1. A reasonable combination of the fluoropolymer A and the copolymer B in a certain mass range can further improve the bonding performance of the binder and the cycling performance of the battery. In any embodiment, the fluoropolymer A is selected from one or more of polyvinylidene fluoride, and the copolymers thereof with tetrafluoroethylene, hexafluoropropylene, and trichloroethylene. In any embodiment, the monomer containing a cyano group is selected from one or more of acrylonitrile, methacrylonitrile, halogenated acrylonitrile, and methoxyacrylonitrile. In any embodiment, the monomer containing an ester group is selected from one or more of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isoamyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate. Compared with fluorine-containing monomers, the above monomer containing a cyano group and monomer containing an ester group have low cost, are not subjected to policy restrictions, can be mass-produced, and can greatly reduce the cost of the binder. In any embodiment, the mass ratio of the structural unit derived from the monomer containing a cyano group to the structural unit derived from the monomer containing an ester group in the copolymer B is 8:1-12:1. The monomer containing a cyano group can improve the mechanical strength and bonding performance of the copolymer B, which can further improve the cycling performance of the battery. A small amount of the monomer containing an ester group can improve the flexibility of the copolymer B and avoid the brittle fracture of the electrode plate; in addition, the ester group has a certain ability to absorb and preserve the electrolyte solution, which can solve the problem of poor io