Aluminum fluoride/silver double-coated lithium nickel cobalt manganese oxide positive electrode material and preparation method thereof

Abstract

The invention relates to an aluminum fluoride / silver double-coated lithium nickel cobalt manganese oxide positive electrode material and a preparation method thereof and belongs to the technical fieldof positive electrode materials for lithium-ion batteries. The aluminum fluoride / silver double-coated lithium nickel cobalt manganese oxide positive electrode material has a core-shell structure; a core is lithium nickel cobalt manganese oxide LiNixCoyMn(1-x-y)O2, wherein x smaller than or equal to 1.0 and greater than or equal to 0.5 and y is smaller than or equal to 0.23 and greater than or equal to 0; and a shell of the core-shell structure comprises an inner shell and an outer shell, wherein the inner shell is aluminum fluoride and the outer shell is silver. The aluminum fluoride / silver double-coated lithium nickel cobalt manganese oxide positive electrode material has excellent cycle performance, high initial charge-discharge efficiency and excellent safety performance.

Description

technical field [0001] The invention relates to an aluminum fluoride / silver double-layer coated nickel-cobalt lithium manganese oxide positive electrode material and a preparation method thereof, belonging to the technical field of lithium-ion battery positive electrode materials. Background technique [0002] At present, lithium-ion battery cathode materials are widely researched and applied for lithium cobalt oxide materials, lithium manganese oxide materials, lithium iron phosphate materials, and ternary materials. However, cobalt in lithium cobaltate cathode material is a rare resource, which is expensive and pollutes the environment; although lithium nickelate has a high theoretical specific capacity, it is difficult to synthesize and the reproducibility of the material is poor; although the raw material of lithium manganate is rich in resources, The price is low, but the capacity of spinel lithium manganese oxide is low, the crystal structure is prone to Jahn-Teller ef...

AI Technical Summary

Problems solved by technology

[0003] Although the lithium-nickel-cobalt-manganese composite oxide ternary cathode material has the above-mentioned many advantages, it also has the following defects: 1) Due to the cation mixing effect and the change of the surface microstructure of the material during the first charging process, the first time the ternary material is charged The charge and discharge efficiency is not high; 2) The lithium ion diffusion coefficient and electronic conductivity are low, which makes the rate performance of the material deviate; 3) The ternary material will have a strong side reaction with the organic electrolyte in a wide voltage range, causing its side reaction More, affecting its cycle performance

The Chinese invention patent with the application publication number of CN 106450217A discloses a modification method of nickel-cobalt lithium manganese oxide ternary material, which mainly solves the problem of traditional ternary material carbon coating by carbon-coating the ternary material. The problem of lithium nickel oxide being reduced during the coating process has realized the coating of the carbon layer on the surface of the ternary material; the carbon-coated nickel-cobalt-lithium manganese oxide ternary material improves the first charge and discharge efficiency and improves the lithium ion diffusion coefficient of the material And electronic conductivity, which improves the electrochemical performance of NCM materials, but its electrical conductivity does not improve much, and the compatibility between the coating layer and the electrolyte is average, resulting in an insignificant improvement in its cycle performance, and its safety performance deviation

[0004] The Chinese invention patent with the application publication number CN105958017A discloses a method for preparing an aluminum fluoride-coated nickel-cobalt lithium manganese oxide positive electrode material. and the first charge and discharge coulombic efficiency have been improved to a certain extent, but only aluminum fluoride coating has defects such as poor coating effect, electrical conductivity, cycle performance, and first charge and discharge efficiency.

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