A kind of lithium cobalt oxide cathode material coated with nanometer cobalt lithium phosphate and preparation method thereof

Abstract

The invention relates to a lithium cobalt oxide positive electrode material coated with nano-cobalt phosphate lithium and a preparation method. By regulating the content of lithium carbonate, lithium hydroxide and spinel-like tricobalt tetroxide, the lithium cobalt oxide and phosphate can form a low temperature on the surface of lithium cobalt oxide. A solid-phase in-situ reaction is used to prepare a layered hexagonal lithium cobalt oxide coated with lithium cobalt phosphate nanometers. The invention is mainly used in high-energy density and high-voltage lithium-ion batteries, and its performance can meet the following requirements: the capacity retention rate is over 80% for 800 cycles at 45°C, the thickness expansion is less than 8% when stored at 60°C for 30 days, and the thickness expansion is less than 8% when stored at 85°C for 8 hours. less than 8%. The positive electrode material lithium cobalt oxide surface structure of the present invention does not contain residual lithium carbonate, lithium hydroxide and other lithium sources, and does not contain spinel-like phase cobalt tetroxide, and is lithium cobalt oxide with stable surface structure. The method of the invention has simple process and is easy to realize industrialized production.

Description

technical field [0001] The invention relates to a lithium cobalt oxide positive electrode material coated with nanometer cobalt lithium phosphate and a preparation method, and belongs to the field of lithium ion battery electrode materials. Background technique [0002] Since commercialization in the 1990s, lithium batteries have been widely used due to their high energy density, high charge-discharge efficiency, small self-discharge, long service life, and environmental friendliness. At present, it has been applied to the fields of consumer electronics, aerospace, military, power tools and electric vehicles. With the development of technology, people have higher and higher requirements for the endurance of lithium-ion batteries, and the development of lithium batteries with high energy density (mass energy density and volume energy density) has become the key. The development of high energy density lithium batteries can start from two aspects, one is to develop new positiv...

AI Technical Summary

Problems solved by technology

The surface structure of lithium cobalt oxide contains a small amount of spinel phase Co 3 o 4 It will reduce the capacity of lithium cobalt oxide battery and shorten the battery life

On the other hand, in the battery, after high-voltage, high-temperature and long-term cycling, the trivalent cobalt on the surface of lithium cobaltate will be reduced to a low-valence state, forming a spinel phase Co on the surface of lithium cobaltate. 3 o 4 , thus deteriorating the long-term cycle performance of the battery

[0006] When charging and discharging under high voltage, the cycle performance of lithium cobalt oxide becomes worse, and the main reason for the rapid capacity decay is that the O3 phase changes to the H1-3 phase in the high delithiation state, and the further delithiation changes from the H1-3 phase to the O1 phase. Lattice loss of oxygen causes structural instability

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