Low cobalt positive electrode active material, method for preparing same, electrochemical device, and electronic apparatus

Abstract

The invention provides a low-cobalt positive electrode active material, a preparation method thereof, an electrochemical device and electronic equipment, and the preparation method comprises the following steps: (1) mixing a nickel salt, a cobalt salt, a manganese salt, a complexing agent and a precipitant, and carrying out a co-precipitation reaction to obtain a precursor inner core; (2) increasing the molar concentration of the cobalt salt, reducing the molar concentration of the manganese salt, and carrying out coprecipitation reaction to obtain a low-cobalt precursor; and (3) mixing the low-cobalt precursor with a lithium salt, and sintering to obtain the low-cobalt positive electrode active material, the molar concentration ratio of the nickel salt to the cobalt salt to the manganese salt in the step (1) is x: y: (1-x-y), x is more than or equal to 0.55 and less than or equal to 0.60, and y is more than or equal to 0.05 and less than or equal to 0.15. According to the preparation method, the defects of low capacity and poor storage caused by coating cobalt through pyrogenic sintering are overcome, the crystallinity, the interface stability and the dynamic performance of the material are improved, and then the gram volume, the coulombic efficiency and the capacity retention rate of an electrochemical device are improved.

Description

technical field [0001] The invention belongs to the technical field of batteries, and relates to a low-cobalt positive electrode active material, a preparation method thereof, an electrochemical device and electronic equipment. Background technique [0002] Ternary materials have higher theoretical specific capacity and voltage platform, but the cost of cobalt in ternary materials is higher, and reducing cobalt content can save product cost; however, the reduction of cobalt content in ternary materials will affect the overall conductivity of the material , increase the diffusion barrier of lithium ions in the lattice, so that the reaction kinetics of the material will be sluggish, and ultimately affect the capacity of the material. [0003] At present, when low-cobalt ternary materials are sintered by fire method, coating cobalt on the surface can solve the kinetic problem of the material, but only when the secondary sintering temperature is at a high temperature of 700°C to...

AI Technical Summary

Problems solved by technology

The present invention controls the concentration of the metal salt and performs a two-step co-precipitation reaction to obtain a low-cobalt positive electrode active material with low cobalt inside and cobalt-rich surface, which solves the shortcomings of low capacity and poor storage caused by fire sintering coated cobalt. The prepared material has uniform particles, good sphericity, narrow particle size distribution, high crystallinity and interface stability, and excellent kinetic properties. It has high gram capacity, Coulombic efficiency and capacity retention when applied to electrochemical devices. Rate

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