A kind of preparation method of high rate nickel cobalt lithium aluminate cathode material

Abstract

The invention discloses a method for preparing a high-rate nickel cobalt lithium aluminate anode material. The method comprises the following steps: (1) preparing a nickel cobalt lithium aluminate precursor; (2) performing lithium-site doping and modifying on potassium ions; and (3) constructing a cladding layer of a lithium-containing compound. According to the method, the dispersing speed of lithium ions is effectively increased by lithium-site replacement of potassium ions, and the rate capability of a material can be improved; the lithium-containing compound layer constructed on the material surface can be used for reducing the content of alkali remained on the material surface and reduce later cell bubbling; side reaction can be effectively inhibited, and the material structure stability in the cycling process can be promoted; and the lithium-containing compound layer has high conducting performance for lithium ions, embedding and separating of lithium ions can be accelerated, the problem of poor lithium ion conductivity when conventional metal oxide is used as the cladding layer can be solved, and the cycling performance and rate performance of the material can be improved.

Description

technical field [0001] The invention belongs to the field of positive electrode materials of lithium ion batteries, and in particular relates to a preparation method of a high-rate nickel-cobalt lithium aluminate positive electrode material. [0002] technical background [0003] Lithium-ion batteries have been widely used in mobile phones, notebook computers and other fields due to their advantages such as high energy, long life, and no pollution. At the same time, they have also begun to be used in power batteries such as electric bicycles and electric vehicles. Lithium cobalt oxide cathode material is the earliest cathode material to be commercialized, but its further development is limited due to limited cobalt resources, high price and high pollution. High nickel-based cathode materials Li(Ni x m 1-x )O 2 (x≥0.6) has become an important cathode material for lithium-ion batteries due to its low cost, high capacity and environmental friendliness. as LiNiO 2 、LiCoO 2 ...

AI Technical Summary

Problems solved by technology

[0004] There are still some problems in the application of NCA materials in batteries: (1) Due to the cation mixing effect and the phase change of the material surface microstructure, the irreversible capacity loss and cycle performance of NCA are caused; (3) The diffusion coefficient of lithium ions is low, which makes the rate performance of the material not very ideal

[0005] At present, the research on the doping modification of NCA materials is basically the ion substitution of the transition metal layer. Although the electrochemical performance of the material can be improved to a certain extent, the ion substitution of the transition metal layer cannot promote the migration rate of lithium ions.

For example, the invention with the application number 201410445867.8 discloses nickel-cobalt lithium aluminate positive electrode material and its preparation method, but the disclosed positive electrode material is the ion substitution of the transition metal layer, which can stabilize the lattice structure, but cannot promote the migration rate of lithium ions

The coating materials used for surface coating of NCA materials are oxides / phosphates, etc. The coating layer hinders the corrosion of the material by the electrolyte and inhibits the side reaction between the material and the electrolyte, but at the same time because of its electrochemical inertness , will also hinder the conduction of electrons and lithium ions

For example, the invention with the application number 201410004698.4 is respectively modified by coating with alumina. Since these substances are electrochemically inert substances, they will hinder the capacity of the active material.

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