High-capacity single-crystal positive electrode material and preparation method thereof

Abstract

The invention discloses a high-capacity single-crystal positive electrode material and a preparation method thereof, and the method comprises the following steps: (1) preparing high-nickel nickel-cobalt-manganese ternary precursor powders a and b, adding a parts of the powders into a titanium source, a zirconium source and a lithium source, and mixing to obtain mixed powder A; adding b parts of the powders into a magnesium source, a fluorine source and a lithium source, and mixing to obtain mixed powder B; (2) heating the mixed powder A, preserving heat, introducing oxygen atmosphere, cooling, crushing and screening to obtain single crystal powder D; and (3) fully mixing the single crystal powder D obtained in the step (2) and the mixed powder B obtained in the step (1), heating, preserving heat, introducing oxygen atmosphere, crushing and sieving to obtain a product F. According to the present invention, the two-time single crystal junction method is performed, the inner layer of the generated single crystal is extremely high nickel nickel cobalt lithium manganate so as to effectively improve the single crystal capacity, the outer layer is medium high nickel nickel cobalt lithium manganate so as to ensure the material stability, and the inner layer and the outer layer are doped with different elements so as to effectively improve the lithium ion diffusion rate in the single crystal and improve the capacity of the single crystal positive electrode material.

Description

technical field [0001] The invention belongs to the field of single crystal materials, and more specifically relates to a high-capacity single crystal cathode material and a preparation method thereof. Background technique [0002] Lithium nickel cobalt manganate (NMC) and lithium nickel cobalt aluminate (NCA) ternary cathode materials can provide high energy density and power density, and have been widely used in new energy vehicle power batteries. At present, most commercialized ternary cathode materials are secondary spherical polycrystalline materials of about 10 microns formed by the aggregation of nano-scale primary particles. There are a large number of grain boundaries inside polycrystalline NMC. During the charging and discharging process of the battery, due to the anisotropic lattice change, polycrystalline NMC is prone to grain boundary cracking, resulting in secondary particle breakage, rapid increase in specific surface area and interface side reactions, result...

AI Technical Summary

Problems solved by technology

[0009] Aiming at the difficulty of lithium ion diffusion in the existing single crystal positive electrode material, which leads to low discharge capacity and rate performance, the present invention provides a high-capacity single crystal positive electrode material and a preparation method thereof, which can improve the discharge capacity of the single crystal material. The problem is that the prepared high-capacity single crystal positive electrode material is divided into two layers, the inner layer is extremely high nickel nickel cobalt lithium manganate doped with titanium and zirconium elements, which can expand the lattice parameters of the single crystal and increase the diffusion rate of lithium ions. It can also inhibit the cation mixing of Li / Ni and reduce the irreversible capacity, and the extremely high nickel can increase the capacity of single crystal materials; the outer layer is medium-high nickel nickel cobalt lithium manganate doped with magnesium and fluorine elements, and magnesium can increase the capacity of the material , fluorine can improve the stability, stabilize the interfacial reaction between the active material and the electrolyte, and the medium-high nickel ensures the stability of the material

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