High-nickel positive electrode material with reconstructed primary particle surface layer and preparation method thereof

Abstract

The invention relates to a high-nickel positive electrode material with a reconstructed surface layer and a preparation method thereof, and belongs to the field of chemical energy storage batteries. The chemical formula of the material is Li(Ni<x>Co<1-x>)<1-y-z>M<y>N<z>O<2>, x is larger than 0.7 and smaller than 1, y is larger than 0 and smaller than or equal to 0.1, z is larger than 0 and smallerthan 0.1, the ratio of y to z is m:1-m, and m is larger than 0.6 and smaller than 1. According to the material, a layered nickel-cobalt positive electrode material is used as a matrix, metal elementsM and N are doped in the surface layers of primary particles of the matrix, and the outermost layer of the surface layers of the primary particles is a rock salt phase NiO thin layer. Surface layer doping is performed on the high-valence metal element M and the trivalent metal element N after high-temperature calcinations to enable more Ni on the surface layer to exist in the form of Ni<2+> by utilizing a charge compensation effect, and a rock salt-like phase NiO thin layer is formed on the surface layer of the primary particle, direct contact between the material and an electrolyte can be effectively isolated, and irreversible phase transformation of the material is inhibited, so that the cycling stability of the material is improved.

Description

technical field [0001] The invention relates to a high-nickel positive electrode material reconstructed on the surface of primary particles and a preparation method thereof, belonging to the field of chemical energy storage batteries. Background technique [0002] The high-nickel layered cathode material is a very promising material, which is different from the traditional LiCoO 2 , LiNiO 2 and LiMnO 2 Compared with lithium-ion batteries, it has the advantages of high specific capacity, high energy density and environmental friendliness, so it gradually occupies an important position in the lithium-ion battery market. [0003] As the nickel content of high-nickel layered cathode materials increases, the specific capacity will increase accordingly, but the problem of poor cycle stability will also appear. A large amount of Ni is oxidized to Ni during charging 4+ , Ni 4+ Reacts with the electrolyte and is reduced to Ni 2+ , then Ni 2+ Occupying the Li site leads to seve...

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Problems solved by technology

[0003] As the nickel content of the high-nickel layered cathode material increases, the specific capacity will increase accordingly, but the problem of poor cycle stability will also appear.

A large amount of Ni is oxidized to Ni during charging 4+ , Ni 4+ Reacts with the electrolyte and is reduced to Ni 2+ , then Ni 2+ Occupying the Li site leads to serious cation mixing, which leads to the destruction of the structural stability of high-nickel cathode materials.

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