Doping-coating modified lithium ion battery layered nickel-rich positive electrode material and preparation method thereof

Abstract

The invention discloses a doping-coating modified lithium ion battery layered nickel-rich positive electrode material and a preparation method thereof. The chemical formula of the lithium ion battery layered nickel-rich positive electrode material is MOx.LiNi1-a-b-c-dCoaMnbAlcMdO2, wherein MOx is a surface modification layer material. The doping-coating modified lithium ion battery layered nickel-rich positive electrode material is prepared through liquid precursor preparation, high-temperature solid sintering and surface modification technologies. Doping modification makes the material have very good lithium ion conductivity, facilitates the de-intercalation of lithium ions, and greatly improves the rate performances of the layered nickel-rich positive electrode material, so the power density and the energy density of the lithium ion battery positive electrode material are improved. Surface coating modification is used to reduce the alkali content of the surface of the material, reduce side reactions and improve the cycle performances and the safety performance of the layered nickel-rich positive electrode material; and the method has the advantages of simple process, easiness in structure control, and realization of industrial large-scale production.

Description

technical field [0001] The invention belongs to the technical field of preparation of lithium-ion battery electrode materials, and in particular relates to a layered nickel-rich positive electrode material of a doped and coated modified lithium-ion battery and a preparation method thereof. Background technique [0002] In recent years, with the development requirements brought about by the technological innovation of electric vehicles, higher requirements have been placed on the energy density of lithium-ion batteries for power batteries. Layered nickel-rich cathode material LiNi x co y m z (wherein, 0.5≤x≤1, M is one or more of Mn, Al, Zn, Mg, Ti, Zr, and V), it is the cathode material of lithium-ion power batteries that has received the most attention in recent years, and has high energy , low cost, good safety and other characteristics, showing excellent electrochemical performance, is expected to become the leading power battery cathode material in the future market. ...

AI Technical Summary

Problems solved by technology

[0003] However, with the increase of nickel content, the layered nickel-rich cathode material has inherent defects and structural changes, although the specific capacity increases, which is very difficult for industrial application.

During the cycle of layered nickel-rich cathode materials, especially under special conditions such as high pressure and high temperature, the oxidized Ni 4+ It will have a side reaction with the electrolyte, causing the structure to collapse irreversibly, and the impedance of the material itself will increase, causing serious safety problems, which is the key to restricting its large-scale application

In addition, lithium-nickel mixed discharge occurs during the reaction process of nickel-rich cathode materials, which leads to the release of active oxygen and generates a large amount of lithium residue Li on the surface of the material. 2 O or LiOH, and absorb a large amount of H when in contact with air 2 O / CO 2 , accumulate a large amount of lithium residue and moisture on the surface of the material, which greatly affects the processing performance of the material, and at the same time produces the problem of flatulence of the material, resulting in attenuation of cycle performance, and finally the deterioration of the overall electrochemical performance of the material and failure

[0004] In general, metal ion doping is an effective method to improve the long-term cycle stability of layered nickel-rich materials, but it cannot reduce the direct contact between the material and the air or electrolyte, and reduce the generation of lithium residues on the surface of the material.

Although the surface residue can be added to the washing step in the preparation process, nickel-rich materials are very sensitive to moisture, and are prone to delithiation reactions and the surface crystal structure is destroyed, thereby reducing the electrochemical performance of the material.

Images