CN-115312757-B - Positive electrode material and preparation method and application thereof

CN115312757BCN 115312757 BCN115312757 BCN 115312757BCN-115312757-B

Abstract

The invention provides a positive electrode material, and a preparation method and application thereof. The preparation method comprises the following steps of mixing a high-nickel positive electrode material to be treated with potassium hexafluoronickelate, and performing heat treatment in an oxygen atmosphere to obtain the positive electrode material. According to the invention, the high-nickel positive electrode material to be treated is oxidized by adopting the potassium hexafluoronickelate, and nickel and fluorine are doped on the surface layer of the high-nickel positive electrode material, so that the problem that divalent nickel is generated by decomposing trivalent nickel on the surface of the positive electrode material in the oxidation sintering process is solved, the mixed discharge of lithium and nickel is reduced, and meanwhile, an electrochemically inert metal material or impurities which are difficult to remove are not introduced, so that the capacity and the circulation stability of the positive electrode material are improved.

Inventors

YU HAIJUN
LI CHANGDONG
XIE YINGHAO
LI AIXIA

Assignees

广东邦普循环科技有限公司
湖南邦普循环科技有限公司

Dates

Publication Date: 20260505
Application Date: 20220815

Claims (12)

1. A method for preparing a positive electrode material, comprising the steps of: mixing the high-nickel anode material with potassium hexafluoronickelate, and performing heat treatment in an oxygen atmosphere to obtain an anode material with a surface layer doped with fluorine and nickel; the addition amount of the potassium hexafluoronickelate is 5-10% of the mass of the high-nickel positive electrode material; The temperature of the heat treatment is 200-250 ℃; the heat treatment time is 1-3 hours; the high nickel positive electrode material has a nickel stoichiometry >0.8.
2. The method for producing a positive electrode material according to claim 1, characterized in that the method for producing a high nickel positive electrode material comprises: And mixing the high-nickel positive electrode precursor with a lithium source, and sintering in an oxygen atmosphere to obtain the high-nickel positive electrode material.
3. The method for preparing a positive electrode material according to claim 2, wherein the chemical formula of the high nickel positive electrode precursor is Ni x Co y M 1-x-y (OH) 2 , x >0.8, y is equal to or greater than 0, and M comprises Mn and/or Al.
4. The method of preparing a positive electrode material according to claim 3, wherein x >0.9 in the chemical formula Ni x Co y M 1-x-y (OH) 2 of the high nickel positive electrode precursor.
5. The method of producing a positive electrode material according to claim 2, wherein the lithium source comprises lithium hydroxide.
6. The method for preparing a positive electrode material according to claim 2, wherein the sintering temperature is 750-800 ℃.
7. The method for preparing a positive electrode material according to claim 2, wherein the sintering time is 8 to 20 hours.
8. The method for preparing a positive electrode material according to claim 7, wherein the sintering time is 8 to 12 hours.
9. The method for producing a positive electrode material according to claim 2, wherein the heat-treated substance is sequentially subjected to water washing and drying.
10. The method for producing a positive electrode material according to claim 1, characterized in that the method for producing comprises the steps of: (1) Mixing a high-nickel positive electrode precursor with lithium hydroxide, and sintering for 8-12 hours at a sintering temperature of 750-800 ℃ in an oxygen atmosphere to obtain a high-nickel positive electrode material; (2) Mixing the high-nickel cathode material in the step (1) with potassium hexafluoronickelate, wherein the addition amount of the potassium hexafluoronickelate is 5-10% of the mass of the high-nickel cathode material, performing heat treatment for 1-3 hours at the temperature of 200-250 ℃ in an oxygen atmosphere, washing with water, and drying to obtain the cathode material; Wherein the chemical general formula of the high-nickel positive electrode precursor is Ni x Co y M 1-x-y (OH) 2 , x is more than 0.9, y is more than or equal to 0, and M comprises Mn and/or Al.
11. The positive electrode material is characterized by being prepared by the preparation method of the positive electrode material according to any one of claims 1-10, wherein the surface layer of the positive electrode material is doped with fluorine and nickel.
12. A lithium ion battery is characterized in that, the lithium ion battery comprises the positive electrode material of claim 11.

Description

Positive electrode material and preparation method and application thereof Technical Field The invention belongs to the technical field of lithium ion batteries, and relates to a positive electrode material, a preparation method and application thereof. Background The battery materials are classified into a positive electrode material, a negative electrode material, a separator, an electrolyte, and the like. The positive electrode material is one of key materials for manufacturing the lithium ion battery, occupies more than 25% of the battery cost, and the performance of the positive electrode material directly influences various performance indexes of the battery, and occupies a core position in the lithium ion battery. The lithium battery anode materials which are already commercialized at present comprise products such as lithium cobalt oxide, lithium manganate, lithium nickelate, lithium iron phosphate, ternary materials and the like, wherein the ternary materials integrate the advantages of the three materials, the cost is greatly reduced, the cycle performance is good, and the comprehensive performance of the ternary materials is superior to that of any single anode material. The high-nickel ternary lithium ion battery anode material has the advantages of high specific capacity, low cost, excellent safety and the like, becomes a research hot spot, and is considered as the lithium ion power battery anode material with great application prospect. However, the high nickel content simultaneously brings the problems of unstable structure and serious high-temperature flatulence, especially nickel and lithium mixed discharge, divalent nickel ions intercalated into a lithium layer are oxidized into trivalent nickel ions in the process of lithium ion removal, so that the local structure collapses, lithium ions are more difficult to intercalate into collapsed sites, and capacity loss is caused. Therefore, the research of reducing nickel-lithium mixed discharge aiming at the pre-oxidation of the ternary positive electrode material precursor has very important practical significance. In the formation of high nickel positive electrode materials (Ni > 0.6), such as NCM and NCA, oxygen sintering is required to oxidize divalent nickel in its precursor to trivalent. With the increase of nickel content, it is difficult to oxidize divalent nickel into trivalent nickel by conventional oxidation sintering, and this problem is generally solved by extending the oxidation sintering time or increasing the oxidation sintering temperature in the prior art, however, the effect is poor, because trivalent nickel is easily decomposed to generate divalent nickel at high temperature, and long-time low-temperature sintering leads to significant increase of cost. In the prior art, a precursor is pre-oxidized to improve the oxidation effect of divalent nickel, for example, CN108511746A oxidizes a high-nickel precursor through nitrate, so that trivalent nickel in a precursor material is increased, however, during oxidative sintering, the surface temperature of the positive electrode material is higher than that of an inner layer, divalent nickel is easily decomposed and generated, so that the divalent nickel on the surface of the positive electrode material obtained by the preparation method is still too high, the initial capacity and the cycle performance of the positive electrode material are influenced, and meanwhile, N element which is difficult to remove is introduced. And as CN108461731A, a high-nickel ternary lithium battery anode material and a preparation method thereof are disclosed. The method comprises the steps of dispersing nano oxidant powder and paraffin at a high speed, enabling the paraffin to be uniformly coated on the surface of the nano oxidant powder to form nano oxidant powder with a shell-core structure, then mixing the nano oxidant powder with a nickel source, a cobalt source and a manganese source, carrying out precipitation treatment, further mixing the nano oxidant powder with a lithium source, and carrying out sintering to remove organic matters to obtain the high-nickel ternary lithium battery anode material. Therefore, how to reduce the problem of trivalent nickel decomposition in the oxidation sintering process of the high-nickel positive electrode material and improve the capacity and the cycle performance of the high-nickel positive electrode material is a technical problem to be solved urgently. Disclosure of Invention The invention aims to provide a positive electrode material, and a preparation method and application thereof. According to the invention, the high-nickel positive electrode material to be treated is oxidized by adopting the potassium hexafluoronickelate, and nickel and fluorine are doped on the surface layer of the high-nickel positive electrode material, so that the problem that divalent nickel is generated by decomposing trivalent nickel on the surface of the positive electrode materia