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EP-4737397-A2 - TERNARY POSITIVE ELECTRODE MATERIAL WITH LOW GAS GENERATION AND HIGH CAPACITY

EP4737397A2EP 4737397 A2EP4737397 A2EP 4737397A2EP-4737397-A2

Abstract

This disclosure relates to the field of electrochemistry, and in particular, to a positive electrode material. The positive electrode material of this disclosure includes a substrate, with a formula of the substrate being Li x Ni y Co z M k Me p O r A m , where 0.95 ≤ x ≤ 1.05, 0.50 ≤ y ≤ 0.95, 0 ≤ z ≤ 0.2, 0 ≤ k ≤ 0.4, 0 ≤ p ≤ 0.05, 1 ≤ r ≤ 2, 0 ≤ m ≤ 2, m+r ≤ 2; a coating layer is disposed on the substrate, where the coating layer includes a coating element; absorbance of nickel leachate per unit mass of the positive electrode material w ≤ 0.7; the coating layer comprises an inner coating layer, the inner coating layer is located on surfaces of at least some primary particles inside the substrate, and the inner coating layer comprises a coating element, wherein the coating element of the inner coating layer is selected from one or more of Al, Zr, Ba, Zn, Ti, Co, W, Y, Si, Sn, B, and P; and wherein the coating layer comprises an outer coating layer, the outer coating layer is located on a surface of the substrate, and the outer coating layer comprises a coating element, wherein the coating element of the outer coating layer is selected from one or more of Al, Zr, Ba, Zn, Ti, Co, W, Y, Si, Sn, B, and P.

Inventors

  • DU, Rui
  • WANG, Sihui
  • LIU, Yongchao
  • LUO, CHI
  • ZHAO, Deyu
  • LIU, Na

Assignees

  • Contemporary Amperex Technology (Hong Kong) Limited

Dates

Publication Date
20260506
Application Date
20200411

Claims (15)

  1. A positive electrode material, comprising a substrate, with a formula of the substrate being Li x Ni y Co z M k Me p O r A m , wherein 0.95 ≤ x ≤ 1.05, 0.50 ≤ y ≤ 0.95, 0 ≤ z ≤ 0.2, 0 ≤ k ≤ 0.4, 0 ≤ p ≤ 0.05, 1 ≤ r ≤ 2, 0 ≤ m ≤ 2, m+r ≤ 2, M is selected from Mn and/or Al, Me is selected from one or more of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, and Nb, and A is selected from one or more of N, F, S, and Cl; wherein a coating layer is disposed on the substrate, wherein the coating layer comprises a coating element that is selected from one or more of Al, Zr, Ba, Zn, Ti, Co, W, Y, Si, Sn, B, and P; wherein the absorbance of nickel leachate per unit mass of the positive electrode material w ≤ 0.7; wherein the coating layer comprises an inner coating layer, the inner coating layer is located on surfaces of at least some primary particles inside the substrate, and the inner coating layer comprises a coating element, wherein the coating element of the inner coating layer is selected from one or more of Al, Zr, Ba, Zn, Ti, Co, W, Y, Si, Sn, B, and P; wherein the coating layer comprises an outer coating layer, the outer coating layer is located on a surface of the substrate, and the outer coating layer comprises a coating element, wherein the coating element of the outer coating layer is selected from one or more of Al, Zr, Ba, Zn, Ti, Co, W, Y, Si, Sn, B, and P; and wherein the absorbance of nickel leachate per unit mass of the positive electrode material is measured as follows: 1) using dimethylglyoxime as the color developing agent, ammonia as the color developing enhancer, and ethanol as the main solvent, a solution A is prepared, where the concentration of dimethylglyoxime in the solution A is 10 g/L, and the concentration of ammonia is 25 to 28 wt%; 2) 1 g of the positive electrode material is added to 10 mL of the solution A, followed by shaking and standing for 24h, and then taking 5 mL of the upper clear solution B; and 3) water is added to the solution B to obtain a 10 mL solution C, and the absorbance of the solution C is measured at a wavelength of 470 nm by using an ultraviolet-visible spectrophotometer
  2. The positive electrode material according to claim 1, wherein a theoretical specific surface area BET 1 of the positive electrode material and an actual specific surface area BET 2 of the positive electrode material satisfy: 0.3 ≤ BET 2 − BET 1 / BET 1 ≤ 5.5 ; wherein, BET 1 = 6 / ρ × D v 50 ; ρ is the actual density of the positive electrode material, measured in g/cm 3 ; and D v 50 is a particle size of the positive electrode material under a cumulative volume distribution percentage reaching 50%, measured in µm.
  3. The positive electrode material according to claim 1 or 2, wherein when the substrate comprises secondary particles composed of primary particles, the actual specific surface area BET 2 of the positive electrode material is 0.1 m 2 /g to 1.0 m 2 /g, and D v 50 is 5 µm to 18 µm.
  4. The positive electrode material according to claim 1 or 2, wherein the substrate comprises single crystal or single-crystal-like particles, the actual specific surface area BET 2 of the positive electrode material is 0.5 m 2 /g to 1.5 m 2 /g, and D v 50 is 1 µm to 6 µm.
  5. The positive electrode material according to any one of claims 1 to 4, wherein a coating element content per unit volume Mv in the positive electrode material is 0.4 mg/cm 3 to 15 mg/cm 3 , preferably 0.8 mg/cm 3 to 10 mg/cm 3 .
  6. The positive electrode material according to claim 1, wherein the outer coating layer comprises a continuous and/or discontinuous coating layer; preferably, the outer coating layer comprises a continuous first coating layer and a discontinuous second coating layer; and more preferably, the second coating layer and the first coating layer comprise different coating elements.
  7. The positive electrode material according to claim 1, wherein in the molecular formula of the substrate, 0.70 ≤ y ≤ 0.90, 0 ≤ z ≤ 0.15, 0 ≤ k ≤ 0.2, and 0 ≤ p ≤ 0.03.
  8. The positive electrode material according to claim 1, wherein in residual lithium on a surface of the positive electrode material, Li 2 CO 3 is less than 3000 ppm, and LiOH is less than 5000 ppm.
  9. The positive electrode material according to claim 8, wherein in the residual lithium on the surface of the positive electrode material, Li 2 CO 3 content is less than LiOH content.
  10. The positive electrode material according to any one of claims 1 to 9, wherein the coating layer includes one or more of aluminum oxide, zirconium oxide, zinc oxide, titanium oxide, silicon oxide, tin oxide, tungsten oxide, yttrium oxide, cobalt oxide, barium oxide, phosphorus oxide, boron oxide, lithium aluminum oxide, lithium zirconium oxide, lithium zinc oxide, lithium magnesium oxide, lithium tungsten oxide, lithium yttrium oxide, lithium cobalt oxide, lithium barium oxide, lithium phosphorus oxide, and lithium boron oxide.
  11. The positive electrode material according to any one of claims 1 to 10, wherein the outer coating layer includes a continuous first coating layer and a discontinuous second coating layer.
  12. The positive electrode material according to claim 11, wherein the second coating layer is located on the surface of the first coating layer or between the first coating layer and the substrate.
  13. The positive electrode material according to claim 11 or 12, wherein an area of a single cell of the discontinuous second coating layer is less than an area of a single cell of the first coating layer.
  14. The positive electrode material according to any one of claim 11 to 13, wherein in the outer coating layer, the second coating layer and the first coating layer include different coating elements.
  15. An electrochemical energy storage apparatus, comprising the positive electrode material according to any one of claims 1 to 14.

Description

TECHNICAL FIELD This disclosure relates to the field of electrochemistry, and in particular, to a ternary positive electrode material with low gas generation and high capacity, and an electrochemical energy storage apparatus. BACKGROUND With escalation of energy crisis and environmental issues, development of new-type green energy sources becomes extremely urgent. Lithium-ion batteries have been applied to various fields due to their advantages of a high specific energy, application at a wide range of temperatures, a low self-discharge rate, a long cycle life, good safety performance, and no pollution. Lithium-ion batteries acting as a vehicle energy system to replace conventional diesel locomotives have been gradually put into trial around the world. However, lithium iron phosphate (LiFePO4) and low nickel ternary (LiNi1/3Co1/3Mn1/3O2) commonly used at present are limited by the material nature itself and cannot fully meet energy density requirements of traction batteries on the positive electrode material of lithium-ion batteries. Increasing nickel content of a high nickel ternary positive electrode material can improve the energy density of batteries. Therefore, high-nickel ternary positive electrode materials are one of main objects of research on traction batteries. However, the increased nickel content obviously aggravates direct side reactions between the positive electrode active material and an electrolytic solution, and greatly deteriorates high temperature gas generation performance, which is one of bottlenecks for commercial mass production of batteries. Currently in terms of material, main methods for improving high temperature gas generation performance all cause different degrees of damage to performance of battery cells, for example, reversible capacity per gram of the active material decreases, and cycle performance deteriorates. SUMMARY In view of the disadvantages in the prior art, this disclosure is intended to provide a ternary positive electrode material with low gas generation and high capacity to resolve problems in the prior art. In order to achieve the above and other related objectives, this disclosure provides a positive electrode material, including a substrate, with a formula of the substrate being LixNiyCozMkMepOrAm, where 0.95 ≤ x ≤ 1.05, 0.50 ≤ y ≤ 0.95, 0 ≤ z ≤ 0.2, 0 ≤ k ≤ 0.4, 0 ≤ p ≤ 0.05, 1 ≤ r ≤ 2, 0 ≤ m ≤ 2, m+r ≤ 2, M is selected from Mn and/or Al, Me is selected from one or more of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, and Nb, and A is selected from one or more of N, F, S, and Cl; a coating layer is disposed on a surface of the substrate, where the coating layer includes a coating element that is selected from one or more of Al, Zr, Ba, Zn, Ti, Co, W, Y, Si, Sn, B, and P; and absorbance of nickel leachate per unit mass of the positive electrode material w ≤ 0.7. According to another aspect, this disclosure provides an electrochemical energy storage apparatus, including the positive electrode material according to this disclosure. Compared with the prior art, this disclosure provides the following beneficial effects: The positive electrode material of this disclosure has good crystal structural stability and surface inertness. Absorbance of nickel leachate of the positive electrode material is relatively low, so that side reactions between the positive electrode material and an electrolytic solution can be effectively inhibited, thereby optimizing cycle performance, improving thermal stability and alleviating gas generation. DESCRIPTION OF EMBODIMENTS The following describes in detail the lithium-ion battery of this disclosure and a preparation method thereof. A first aspect of this disclosure provides a positive electrode material, including a substrate, with a formula of the substrate being LixNiyCozMkMepOrAm, where 0.95 ≤ x ≤ 1.05, 0.50 ≤ y ≤ 0.95, 0 ≤ z ≤ 0.2, 0 ≤ k ≤ 0.4, 0 ≤ p ≤ 0.05, 1 ≤ r ≤ 2, 0 ≤ m ≤ 2, m+r ≤ 2, M is selected from Mn and/or Al, Me is selected from one or more of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, and Nb, and A is selected from one or more of N, F, S, and Cl; a coating layer is disposed on the substrate, where the coating layer includes a coating element that is selected from one or more of Al, Zr, Ba, Zn, Ti, Co, W, Y, Si, Sn, B, and P; and absorbance of nickel leachate per unit mass of the positive electrode material w ≤ 0.7. In an embodiment of this disclosure, a method for determining absorbance w of nickel leachate per unit mass of the positive electrode material may typically include: putting the positive electrode material of unit mass into a suitable solution, and measuring absorbance of the resultant leachate under a specified wavelength range. In a specific embodiment of this disclosure, a method for determining absorbance w of nickel leachate per unit mass of the positive electrode material may specifically include the following steps: storing 1 g of the positive electrode material into 10 mL ethanol solution with