A kind of surface modification method of nickel-rich cathode material

Abstract

The invention discloses a surface modification method of a nickel-rich cathode material. The surface modification method comprises the following steps of: adding the cathode material and an oxidizing agent into a solvent, uniformly dispersing, and carrying out drying, sintering, washing, drying and grinding, thereby obtaining the surface modified nickel-rich cathode material, wherein the solvent is water or an organic solvent, the organic solvent is methanol or / and ethanol, the cathode material is a ternary cathode material, the chemical formula of the cathode material is LiNi<x>Co<y>Mn<1-x-y>O2, a is more than 0.9 and less than 1.05, x is more than 0.4 and less than 0.8, and y is more than 0.05 and less than 0.4. According to the surface modification method disclosed by the invention, the surface of the cathode material is modified, the influence of all conditions on the performance of the substrate cathode material during synthesis process can be avoided, meanwhile, the oxidizing agent is used for processing the cathode material, Ni<2+> in the surface of the material can be oxidized into Ni<3+>, the Ni<2+> in the surface of the nickel-rich lithium ion ternary cathode material is reduced, and mixed arranging of Ni<2+> / Li<+> in the material is further reduced greatly.

Description

technical field [0001] The invention belongs to the field of lithium ion battery materials, and in particular relates to a surface modification method of a nickel-rich positive electrode material. Background technique [0002] As a cathode material for lithium-ion batteries, layered nickel-rich ternary cathode materials have relatively low cost and abundant material resources, relatively simple manufacturing process, relatively high specific capacity and specific energy, environmental friendliness and relatively long cycle life. and other advantages, so it is the main positive electrode material for lithium-ion batteries, especially large-scale lithium-ion power batteries. [0003] The increase of the content of nickel in the layered nickel-rich ternary cathode material helps to increase the specific capacity of the cathode material, so as to achieve the purpose of increasing the specific energy of the entire battery system, but when the nickel content in the cathode materia...

AI Technical Summary

Problems solved by technology

For ternary cathode materials, reducing the content of nickel can effectively reduce the Ni 2+ The content can effectively inhibit lithium-nickel mixing, but because in the layered ternary cathode material, one of the main redox pairs is Ni 2+ / 3+ / 4+ , the reduction of nickel content will significantly reduce the capacity of the material, and at the same time reduce the discharge platform and compaction density of the material, which is not conducive to the application of the material in large-capacity electrical equipment

[0007] (3) In the process of synthesizing materials, by doping certain metals or compounds, the stability of the material's own structure can be enhanced, and the material Ni can be reduced. 2+ content, reduce the internal resistance, and improve the cycle performance of the material, but it will reduce the first charge and discharge capacity of the material, which is not conducive to the full use of the material capacity

However, the decomposition products of some additives are insulating substances, which cover the surface of the material and inhibit Li + Free movement during charge and discharge degrades capacity and rate performance

In addition, the content of additives and experimental environmental conditions need to be strictly controlled, and various tiny factors will seriously affect the experimental results, and the harsh production requirements are not conducive to large-scale use

Images