A modification method of lithium-ion battery cathode lithium-rich material

Abstract

The invention relates to a lithium ion battery anode lithium-rich material modification method which includes the steps: doping elements in the process of preparing a precursor; coating the doped precursor by coatings; performing high-temperature calcining to obtain doped lithium-rich manganese-based materials coated with lithium titanate. Coating modification and doping modification are integrated, and the modification method overcomes the shortcomings that the rate performance or cycling performance of a lithium-rich anode material can only be unilaterally improved by a traditional modification method, and the specific discharge capacity of the material is greatly affected. The modified material has high discharge capacity and coulombic efficiency and fine circulation capacity retention rate and rate characteristics by the lithium-rich material modification method.

Description

technical field [0001] The invention relates to the preparation and modification of positive electrode materials of lithium ion batteries, in particular to a method for modifying lithium-rich positive electrode materials of lithium ion batteries. Background technique [0002] As a new type of high-energy storage battery, lithium-ion batteries have the advantages of high energy density, long service life, good cycle performance and no memory effect, and are widely used in electronic devices such as mobile phones and digital cameras. The battery cathode material is an important part of the lithium-ion battery, which determines many key performances of the lithium-ion battery. Among the current commercial lithium-ion battery cathode materials, lithium cobalt oxide occupies the main market, but due to the scarcity of Co resources, high price, poor safety performance, and high toxicity, lithium-ion batteries and their cathode materials are seriously affected and restricted. deve...

AI Technical Summary

Problems solved by technology

Although the lithium-rich material xLi 2 MnO 3 ·(1-x)LiMO 2 (M=Co, Ni 0.5 mn 0.5 , Cr, Ni 1 / 3 co 1 / 3 mn 1 / 3 , Fe...) has a very high specific capacity, but the intrinsic electronic conductivity and ionic conductivity of the material are poor, and the dissolution of Mn and the Jahn-Teller effect may occur, which will lead to low first Coulombic efficiency, poor rate performance and cycle poor performance

CN10156562245A reports a kind of MnO 2 Surface coating of lithium-rich cathode materials improves the initial irreversible capacity and cycle performance at high rates, but the discharge capacity is low at low currents

US7678503B2 reported a method of coating the surface of lithium-rich cathode materials with oxides, which improved the first discharge capacity and Coulombic efficiency of the material, but the electrochemical performance of the material at high rates was not significantly improved by coating

CN103606673A has reported a kind of fast ion conductor Li 4 Ti 5 o 12 Coating lithium-rich materials improves initial discharge capacity and rate performance without improving cycle performance

[0005] In summary, there are the following technical problems in the prior art: although the lithium-rich material xLi 2 MnO 3 ·(1-x)LiMO 2 (M=Co, Ni 0.5 mn 0.5 , Cr, Ni 1 / 3 co 1 / 3 mn 1 / 3 , Fe...) has a very high specific capacity, but the intrinsic electronic conductivity and ionic conductivity of the material are poor, and the dissolution of Mn and the Jahn-Teller effect may occur, which will lead to low first Coulombic efficiency, poor rate performance and cycle poor performance

The traditional coating modification method can only unilaterally improve the rate performance or cycle performance of lithium-rich cathode materials, and will also greatly affect the specific discharge capacity of the material.

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