Composite coated nickel-rich positive electrode material as well as preparation method and application thereof

Abstract

The invention discloses a composite coated nickel-rich positive electrode material as well as a preparation method and application thereof, and belongs to the technical field of lithium ion battery positive electrode materials. The composite coated positive electrode material comprises a nickel-rich positive electrode base material, a transition layer and a composite coating layer coated on the surface of the base material. The composite coating layer is composed of the composite solid electrolyte and the lithium-boron compound, the positive electrode material can be effectively protected through the combined action of the composite solid electrolyte and the lithium-boron compound, the safety performance of the material is improved, and the rate capability of the material can be further improved.

Description

technical field [0001] The invention relates to the technical field of positive electrode materials for lithium ion batteries, in particular to a composite-coated nickel-rich positive electrode material and a preparation method and application thereof. Background technique [0002] As the power market requires higher and higher energy density of lithium-ion batteries, nickel-rich materials have received extensive attention and research. However, its rate performance still cannot fully meet the requirements of power batteries for fast charging performance, and its safety performance is the biggest bottleneck in the use of high-nickel materials at present. For the improvement of the rate performance, ion doping can improve the ionic conductivity of the material, reduce the particle size and shorten the ion transmission path, etc., and related research is very extensive. For the improvement of safety performance, the safety performance can be improved by coating the surface wi...

AI Technical Summary

Problems solved by technology

[0004] Chinese patent CN110858643B achieves the effect of surface coating by forming a solid electrolyte in situ on the surface. Since the solid electrolyte requires a high heat treatment temperature, a solid electrolyte material with a relatively complete crystal structure can be obtained, showing a high ion conductivity. If At a lower sintering temperature, the crystallinity of the formed material is lower, and due to the lower sintering temperature, more grain boundaries will be formed between the particles, and at the same time, amorphous substances and impurities will be formed, which will significantly affect the The ionic conductivity of the material will affect the rate performance of the positive electrode material, and if the sintering temperature is too high, especially the structure of the nickel-rich ternary material is easily destroyed at high temperature, which will affect the electrical properties of the material, and the two cannot have both

[0005] Chinese patent CN111900394B forms a solid electrolyte layer containing lithium borate, titanium aluminum phosphate and other solid electrolyte layers through in-situ coating to improve cycle performance, but because lithium titanium aluminum phosphate is formed at a lower temperature, the ion conductivity is low, and the boron source is relatively low. At high temperature, it will react with a large amount of lithium ions in the positive electrode material, thereby destroying the bulk structure of the material. Due to the different applicable temperatures of lithium borate and lithium titanium aluminum phosphate coated positive electrode materials, it is difficult to take into account different types of solid electrolytes simultaneously. Coated use, which will affect the electrochemical performance of the positive electrode material

[0006] Chinese patent CN102347471B coats aluminum phosphate in situ on the surface of the positive electrode material. The comprehensive and uniform aluminum phosphate coating on the surface is conducive to the improvement of cycle performance, but the ion conductivity of aluminum phosphate itself is low, which will affect the rate performance of the material.

In the current material modification scheme, it is difficult to balance the electrochemical performance, safety performance and cost of the material

Images