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CN-122025582-A - Positive electrode active material, secondary battery, and electricity device

CN122025582ACN 122025582 ACN122025582 ACN 122025582ACN-122025582-A

Abstract

The invention relates to a positive electrode active material, a secondary battery and an electric device, wherein the positive electrode active material comprises positive electrode active particles and fluoride coating materials for coating at least part of the surfaces of the positive electrode active particles, the fluoride coating materials comprise a compound shown as a formula I, wherein the formula I is A 7‑(2n+3m) M n M' m F 7‑x R x/y , 0<n is less than or equal to 2, M is less than or equal to 0 and less than or equal to 2, x is less than or equal to 0 and less than or equal to 2, y is the absolute value of the valence state of R, A comprises Na and/or Li, M comprises at least one of Ca, zn, mg, sr, ba, M' comprises at least one of Ga, al, la, Y, B, in, sc, bi, sb, and R comprises at least one of O, S, se, te, cl, br, I, CN, BF 4 、BH 4 .

Inventors

  • OUYANG CHUYING
  • WANG YUQI
  • WANG ZHUO
  • ZHU WENBO
  • XU BO
  • ZHU CHEN
  • WU MUSHENG

Assignees

  • 宁德时代新能源科技股份有限公司

Dates

Publication Date
20260512
Application Date
20250929

Claims (20)

  1. 1. A secondary battery comprising a positive electrode sheet comprising a positive electrode active material, characterized in that the positive electrode active material comprises positive electrode active particles and a fluoride coating material coating at least part of the surface of the positive electrode active particles, the fluoride coating material comprising a compound represented by formula I: A 7-(2n+3m) M n M' m F 7-x R x/y A is a group I Wherein 0<n is less than or equal to 2,0< m 2 is less than or equal to 0 and x is less than or equal to 02, y is the absolute value of the valence state of R; a comprises Na and/or Li; m comprises at least one of Ca, zn, mg, sr, ba; m' includes at least one of Ga, al, la, Y, B, in, sc, bi, sb; R includes at least one of O, S, se, te, cl, br, I, CN, BF 4 、BH 4 .
  2. 2. The secondary battery according to claim 1, wherein M further comprises not more than 10 mole% of a first transition metal element based on the total moles of M, wherein the first transition metal element comprises at least one of Fe, co, ni, mn, cu, ti, cr, V.
  3. 3. The secondary battery according to claim 1, wherein the first transition metal element is selected from at least one of Fe, co, ni, mn, cu, cr, V.
  4. 4. The secondary battery according to any one of claims 1 to 3, wherein M 'further comprises not more than 10 mol% of a second transition metal element based on the total moles of M', wherein the second transition metal element comprises at least one of Fe, co, ni, mn, V, ti, cr.
  5. 5. The secondary battery according to claim 4, wherein the second transition metal element is selected from at least one of Fe, co, ni, mn, V, cr.
  6. 6. The secondary battery according to any one of claims 1 to 5, wherein a further comprises not more than 20 mol% of K and/or Ag based on the total moles of a.
  7. 7. The secondary battery according to any one of claims 1 to 6, wherein M further comprises not more than 10 mole% in total of at least one element of a and at least one element of M', based on the total moles of M.
  8. 8. The secondary battery according to any one of claims 1 to 7, wherein M includes at least one of Ca, zn, mg.
  9. 9. The secondary battery according to any one of claims 1 to 8, wherein M' includes at least one of Ga, al.
  10. 10. The secondary battery according to any one of claims 1 to 9, wherein the positive electrode active material comprises 0.01 to 10 wt% of the fluoride coating material, based on the total weight of the positive electrode active material.
  11. 11. The secondary battery according to any one of claims 1 to 10, wherein the coating thickness of the fluoride coating material is 5 to 20nm.
  12. 12. The secondary battery according to any one of claims 1 to 11, wherein the positive electrode active particles include at least one of a layered oxide material, a spinel oxide material, a fluoride material, wherein: the layered oxide material comprises a compound of formula II: A 1 M a O 2-e/2 R 1 e/f A is a III In the formula II, 0≤e≤0.2, f is the absolute value of the valence state of R 1 , A 1 comprises Li or Na, M a comprises a transition metal element, and R 1 comprises at least one of F, cl; the spinel oxide material includes a compound of formula III: a 2 M b 2 O 4-g/2 R 2 g/h A type III In the formula III, g is more than or equal to 0 and less than or equal to 0.4, h is the absolute value of the valence state of R 2 , A 2 comprises Li or Na, M b comprises a transition metal element, and R 2 comprises at least one of F, cl; The fluoride material includes a compound of formula IV: a 3 7-2k-3p M c k M d p F 7-i R 3 (i/j) IV In the formula IV of the present invention, 0<k is less than or equal to 2,0< p is less than or equal to 2,0 i is more than or equal to 2, j is more than or equal to 2 the absolute value of the valence state of R 3 , A 3 includes Li or Na, M c includes a transition metal element having a divalent valence, M d includes a transition metal element having a trivalent valence, and R 3 includes at least one of F, cl.
  13. 13. The secondary battery according to any one of claims 1 to 12, wherein the positive electrode active material has one or more of the following characteristics: (1) The Dv50 particle size of the positive electrode active material is in the range of 5 to 30 μm; (2) The BET specific surface area of the positive electrode active material is in the range of 0.1 to 14 m 2 /g; (3) The tap density of the positive electrode active material is 1.1 to 2.3 g/cm 3 ; (4) The hardness of the positive electrode active material is in the range of 6 to 12 GPa.
  14. 14. The secondary battery according to any one of claims 1 to 13, wherein the positive electrode tab includes a current collector and a positive electrode film layer disposed on at least one surface of the current collector, the positive electrode film layer including 70 to 98 wt% of a positive electrode active material based on the total weight of the positive electrode film layer.
  15. 15. The secondary battery of claim 14, wherein the positive electrode film layer further comprises a total of 2 to 30 wt% of a binder based on the total weight of the positive electrode film layer.
  16. 16. The secondary battery according to any one of claims 1 to 15, wherein the compacted density of the positive electrode sheet is 2.3 g/cm 3 to 3.7 g/cm 3 .
  17. 17. The secondary battery according to any one of claims 1 to 16, wherein the fluoride coating material has Weberite configuration.
  18. 18. A positive electrode active material comprising positive electrode active particles and a fluoride coating material coating at least part of the surface of the positive electrode active particles, characterized in that the fluoride coating material comprises a compound represented by formula I: a 7-(2n+3m) M n M' m F 7-x R x/y formula I; Wherein 0<n is less than or equal to 2,0< m 2 is less than or equal to 0 and x is less than or equal to 02, y is the absolute value of the valence state of R; a comprises Na and/or Li; m comprises at least one of Ca, zn, mg, sr, ba; m' includes at least one of Ga, al, la, Y, B, in, sc, bi, sb; R includes at least one of O, S, se, te, cl, br, I, CN, BF 4 、BH 4 .
  19. 19. The positive electrode active material of claim 18, wherein M further comprises not greater than 10 mole percent of a first transition metal element based on the total moles of M, wherein the first transition metal element comprises at least one of Fe, co, ni, mn, cu, ti, cr, V.
  20. 20. The positive electrode active material according to claim 19, wherein the first transition metal element is selected from at least one of Fe, co, ni, mn, cu, cr, V.

Description

Positive electrode active material, secondary battery, and electricity device The application is based on the divisional application of Chinese patent application with the application date of 2025, 09 and 29, the application number of 202511411135.1 and the application name of positive electrode active material, secondary battery and electric device. Technical Field The invention relates to the technical field of secondary batteries, in particular to a fluoride coating material, a positive electrode active material comprising positive electrode active particles coated with the fluoride coating material, and a secondary battery. Background Electrochemical degradation phenomena such as voltage drop and capacity decay frequently occur in the battery during the cycling process. In addition, in a high-charge state, oxygen ions in the positive electrode of the oxide participate in oxidation-reduction reaction, and the generated oxygen reacts with the electrolyte to release a large amount of heat, so that the battery is in thermal runaway, and the potential safety hazard is great. Disclosure of Invention The present invention provides a positive electrode active material including positive electrode active particles and a fluoride coating material coating at least part of the surface of the positive electrode active particles, wherein the fluoride coating material has good corrosion resistance and air stability, and simultaneously has high thermodynamic stability, a wide electrochemical window, high ionic conductivity and excellent mechanical properties, which can be adapted to a common high-voltage positive electrode material, so that the positive electrode active particles coated with the same can bring about improvements in battery cycle stability and thermal runaway. A first aspect of the present invention provides a secondary battery including a positive electrode tab including a positive electrode active material. The positive electrode active material comprises positive electrode active particles and fluoride coating materials for coating at least part of the surfaces of the positive electrode active particles, wherein the fluoride coating materials comprise a compound shown in a formula I: A formula I; Wherein 0<n is less than or equal to 2,0< m 2 is less than or equal to 0 and x is less than or equal to 02, y is the absolute value of the valence state of R; a comprises Na and/or Li; m comprises at least one of Ca, zn, mg, sr, ba; m' includes at least one of Ga, al, la, Y, B, in, sc, bi, sb; R includes at least one of O, S, se, te, cl, br, I, CN, BF 4、BH4. The fluoride coating material provided by the invention has high thermodynamic stability, a wide electrochemical window, high ionic conductivity and excellent mechanical properties, and can relieve side reactions between the positive electrode active particles and electrolyte after the positive electrode active particles are coated by the fluoride coating material, so that the positive electrode active particles can work under higher voltage, and therefore, the capacity and energy density of a battery, the first-week coulomb efficiency, the cycling stability, the safety and the rate capability can be improved, and especially, the thermal runaway of the battery can be improved. In the aspect of thermodynamic stability, the anion framework of the fluoride coating material mainly consists of fluoride ions, and fluorine has very high electronegativity (stronger than oxygen and chlorine) and stronger interaction with cations in a structure, so that the structural stability is better, and the fluoride coating material coats at least part of the surface of the positive electrode active particles, so that the structural stability of the positive electrode active particles can be improved, and the cycle stability of a battery is improved. In terms of electrochemical window, the fluoride coating material may have an operating voltage range capable of covering the high voltage anode and electrolyte, with a high voltage resistance significantly stronger than that of oxide. Due to the good electrochemical stability of the coating material, electrochemical side reactions between the high-voltage anode and the electrolyte can be avoided. In terms of ionic conductivity, the fluoride-coated material has a Weberite configuration (also referred to as a magnesium cryolite structure, a magnesium-like cryolite structure) that has three-dimensional ion transport channels, and the alkali metal in the structure is in a higher octacoordinate environment. On one hand, the high coordination environment forms an 'alkali metal cage' with larger space, the migration potential barrier of alkali metal ions is reduced, on the other hand, the alkali metal-F bond in the structure is longer, the binding capacity of the alkali metal ions is weaker, so that the diffusion coefficient of the alkali metal ions is higher, and therefore, the fluoride coating material has excellent ion conductivity