Lithium cobalt oxide positive electrode material coated with nanometer lithium cobalt phosphate and preparation method of lithium cobalt oxide positive electrode material

Abstract

The invention relates to a lithium cobalt oxide positive electrode material coated with nanometer lithium cobalt phosphate and a preparation method of the lithium cobalt oxide positive electrode material. The contents of lithium carbonate, lithium hydroxide and spinel-like phase cobaltosic oxide are regulated and controlled, so the lithium carbonate, the lithium hydroxide and the spinel-like phase cobaltosic oxide undergo a low-temperature solid-phase in-situ reaction with phosphate on the surface of lithium cobalt oxide so as to prepare the layered hexagonal phase lithium cobalt oxide coated with the nanometer lithium cobalt phosphate. The lithium cobalt oxide positive electrode material is mainly used in a high-energy-density high-voltage lithium ion battery, and the performance of the material can meet the conditions that a capacity retention rate is 80% or above after circulation for 800 weeks at 45 DEG C, thickness expansion is less than 8% after storage for 30 days at 60 DEG C, and the thickness expansion is less than 8% after storage for 8 hours at 85 DEG C. The surface structure of the lithium cobalt oxide positive electrode material does not contain residual lithium carbonate, lithium hydroxide and other lithium sources, does not contain spinel-like phase cobaltosic oxide, and is lithium cobalt oxide with a stable surface structure. The method is simple in process and easy to realize industrial production.

Description

Technical field[0001]The present invention relates to a lithium cobalt positive electrode material and a preparation method of cobalt-cobalt-cobalt-cobalt-cobalt-free lithium, belonging to a lithium ion battery electrode material.Background technique[0002]Since commercialization in the 1990s, lithium batteries have been widely used due to high energy density, high charge and discharge efficiency, small self-discharge, long service life and environmentally friendly, and are widely used. It has been applied to consumer electronics, aerospace, military, electric vehicles and electric vehicles. With the development of technology, people's battery life requirements have become higher and higher, and the development of high energy density (mass energy density and volume energy density) lithium battery is critical. Developing high-energy density lithium batteries can start from two aspects, one is to develop a positive and negative electrode material for new high cacar capacity; the second...

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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