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CN-122000353-A - Secondary battery, preparation method thereof, modified conductive agent and power utilization device

CN122000353ACN 122000353 ACN122000353 ACN 122000353ACN-122000353-A

Abstract

The application discloses a secondary battery, a preparation method thereof, a modified conductive agent and an electric device. The secondary battery comprises a positive electrode plate, the positive electrode plate comprises a current collector and a positive electrode active layer loaded on the surface of the current collector, the positive electrode active layer comprises a positive electrode active material and a modified conductive agent, wherein the modified conductive agent comprises a conductive agent and a chelating agent, the chelating agent is connected with the surface of the conductive agent through a chemical bond, the chelating agent comprises a transition metal ion chelating functional group, and the transition metal ion chelating functional group comprises a phosphate group and/or a phosphate group. The chelating agent adopted by the application can be combined with dissolved transition metal ions in the positive electrode active layer through coordination, so that the dissolution and diffusion of the transition metal ions in the battery are inhibited, and the cycle performance of the battery is improved.

Inventors

  • WU XIAN
  • Wang maoxu
  • LIN ZHEN
  • LI WEI

Assignees

  • 宁德时代新能源科技股份有限公司

Dates

Publication Date
20260508
Application Date
20241104

Claims (20)

  1. 1. A secondary battery is characterized by comprising a positive electrode plate, wherein the positive electrode plate comprises a current collector and a positive electrode active layer loaded on the surface of the current collector, the positive electrode active layer comprises a positive electrode active material and a modified conductive agent, Wherein the modified conductive agent comprises a conductive agent and a chelating agent, the chelating agent is connected with the surface of the conductive agent through a chemical bond, the chelating agent comprises a transition metal ion chelating functional group, and the transition metal ion chelating functional group comprises a phosphate group and/or a phosphate group.
  2. 2. The secondary battery according to claim 1, wherein the chelating agent comprises an organic phosphate.
  3. 3. The secondary battery according to claim 1 or 2, wherein the number n of phosphate groups and/or phosphate groups in the chelating agent is not less than 2.
  4. 4. The secondary battery according to any one of claims 1 to 3, wherein the secondary battery comprises a lithium ion secondary battery, and the chelating agent comprises a lithium organophosphate salt, or The secondary battery includes a sodium ion secondary battery, and the chelating agent includes an organic sodium phosphate salt.
  5. 5. The secondary battery according to any one of claims 1 to 4, wherein the chelating agent includes an alkyl main chain in which at least one hydrogen atom attached to a carbon atom is substituted with a transition metal ion chelating functional group represented by formula I, -PO 3 H x M y formula I Wherein M comprises sodium or lithium, x is 0 or a positive integer, y is a positive integer, and x+y=2; The alkyl main chain comprises any one of alkyl with 1-8 carbon atoms, alkyl alcohol with 1-8 carbon atoms and alkylamine with 1-8 carbon atoms and 1-2 nitrogen atoms.
  6. 6. The secondary battery according to claim 5, wherein the number n of the transition metal ion chelating functional groups represented by formula I in the chelating agent is 2 to 6, and/or; The alkyl main chain in the chelating agent comprises any one of alkyl with 1-5 carbon atoms, alkyl alcohol with 1-4 carbon atoms and alkylamine with 2-6 carbon atoms and 1-2 nitrogen atoms.
  7. 7. The secondary battery according to any one of claims 1 to 6, wherein the chelating agent includes at least one of compounds represented by formulas I-1 to I-6:
  8. 8. The secondary battery according to any one of claims 1 to 7, wherein a mass ratio of the conductive agent to the chelating agent is 1 (1.5-18).
  9. 9. The secondary battery according to any one of claims 1 to 7, wherein a mass ratio of the conductive agent to the chelating agent is 1 (3-10).
  10. 10. The secondary battery according to any one of claims 1 to 9, wherein the conductive agent includes at least one of carbon nanotubes, graphene, carbon nanofibers, conductive graphite, conductive carbon black.
  11. 11. The secondary battery according to any one of claims 1 to 10, wherein a mass ratio between the modified conductive agent and the positive electrode active material in the positive electrode active layer is (5-10): (85-90).
  12. 12. An electric device comprising the secondary battery according to any one of claims 1 to 11.
  13. 13. A modified conductive agent comprising a conductive agent and a chelating agent, said chelating agent being attached to the surface of said conductive agent by a chemical bond, said chelating agent comprising a transition metal ion chelating functionality, said transition metal ion chelating functionality comprising a phosphate group and/or a phosphate group.
  14. 14. The modified conductive agent of claim 13, wherein the chelating agent comprises an organophosphate salt.
  15. 15. The modified conductive agent as claimed in claim 13 or 14, wherein the number n of phosphate groups and/or phosphate groups in the chelating agent is not less than 2.
  16. 16. The modified conductive agent according to any one of claims 13 to 15, wherein the chelating agent comprises an alkyl main chain in which at least one hydrogen atom attached to a carbon atom is substituted with a transition metal ion chelating functional group represented by formula I, -PO 3 H x M y formula I Wherein M comprises sodium or lithium, x is 0 or a positive integer, y is a positive integer, and x+y=2; The alkyl main chain comprises any one of alkyl with 1-8 carbon atoms, alkyl alcohol with 1-8 carbon atoms and alkylamine with 1-8 carbon atoms and 1-2 nitrogen atoms.
  17. 17. The modified conductive agent of claim 16, wherein the number n of transition metal ion chelating functionalities of formula I in the chelating agent is 2-6, and/or; The alkyl main chain in the chelating agent comprises any one of alkyl with 1-5 carbon atoms, alkyl alcohol with 1-4 carbon atoms and alkylamine with 2-6 carbon atoms and 1-2 nitrogen atoms.
  18. 18. The modified conductive agent of any one of claims 13 to 17, wherein the chelating agent comprises at least one of the compounds of formulas I-1 to I-6:
  19. 19. the modified conductive agent as claimed in any one of claims 13 to 18, wherein a mass ratio of the conductive agent to the chelating agent is 1 (1.5-18).
  20. 20. The modified conductive agent as claimed in any one of claims 13 to 19, wherein a mass ratio of the conductive agent to the chelating agent is 1 (3-10).

Description

Secondary battery, preparation method thereof, modified conductive agent and power utilization device Technical Field The application relates to the technical field of batteries, in particular to a secondary battery, a preparation method thereof, a modified conductive agent and an electric device. Background The secondary battery is widely used not only in energy storage power supply systems such as hydraulic power, thermal power, wind power and solar power stations, but also in electric vehicles such as electric bicycles, electric motorcycles and electric automobiles, as well as in a plurality of fields such as military equipment and aerospace. Improving the cycle performance of a secondary battery has been a goal pursued in the industry, but during the cycle of the secondary battery, metal ions in the positive electrode of the battery, such as transition metal ions of Ni, co, mn, etc., are dissolved out, and the dissolved metal ions enter the electrolyte and diffuse to the negative electrode through the separator, and are reduced and deposited on the surface of the negative electrode, resulting in the degradation of the reversible cycle capacity of the battery, and thus the cycle performance is reduced. Disclosure of Invention The present application has been made in view of the above problems, and an object of the present application is to provide a secondary battery, a method for producing the same, a modified conductive agent, and an electric device, which solve the problem of degradation of battery cycle performance due to elution of metal ions in a positive electrode of the battery during battery cycle. In order to achieve the above object, in a first aspect, the present application provides a secondary battery, comprising a positive electrode sheet, the positive electrode sheet comprising a current collector and a positive electrode active layer supported on the surface of the current collector, the positive electrode active layer comprising a positive electrode active material and a modified conductive agent, wherein the modified conductive agent comprises a conductive agent and a chelating agent, the chelating agent is connected to the surface of the conductive agent through a chemical bond, the chelating agent comprises a transition metal ion chelating functional group, and the transition metal ion chelating functional group comprises a phosphate group and/or a phosphate group. In the secondary battery, the modified conductive agent adopted in the positive electrode plate comprises the chelating agent connected with the surface of the conductive agent, and the transition metal ion chelating functional group contained in the chelating agent can be combined with the dissolved transition metal ions in the positive electrode active layer through coordination, namely, the phosphoric acid group and/or the phosphate group can fix the dissolved transition metal ions in the positive electrode active layer through coordination, so that the dissolution and diffusion of the transition metal ions in the battery are inhibited, the transition metal ions are prevented from shuttling to the negative electrode, and the problem of reduced cycle performance of the battery is further improved. In any embodiment, the chelating agent comprises an organophosphate. The organic groups contained in the organophosphates are more advantageous for the chelating agent to be attached to the surface of the conductive agent by chemical bonds. In any embodiment, the number n of phosphate groups and/or phosphate groups in the chelating agent is greater than or equal to 2. The suitable number of phosphate groups and/or phosphate groups facilitates the capture and immobilization of dissolved transition metal ions in the positive electrode active layer. In any embodiment, the secondary battery comprises a lithium ion secondary battery, the chelating agent comprises a lithium salt of an organic phosphate, or the secondary battery comprises a sodium ion secondary battery, and the chelating agent comprises a sodium salt of an organic phosphate. The lithium ion secondary battery adopts the organic lithium phosphate, which is favorable for releasing lithium ions in the use process of the battery, and is used as a lithium supplementing agent to improve the capacity of the battery, thereby further improving the cycle performance of the battery. Similarly, the organic sodium phosphate is adopted in the sodium ion secondary battery, so that sodium ions are released in the use process of the battery, and the organic sodium phosphate is used as a sodium supplementing agent, so that the capacity of the battery is improved, and the cycle performance of the battery is further improved. In any embodiment, the chelating agent comprises an alkyl backbone and a transition metal ion chelating functionality of formula I, at least one hydrogen atom in the alkyl backbone attached to a carbon atom is replaced with a transition metal ion chelating functional