Preparation method of semi-doped and semi-coated NCA positive electrode material

Abstract

The invention discloses a preparation method of a semi-doped and semi-coated NCA positive electrode material, and belongs to the technical field of positive electrode materials of non-aqueous electrolyte secondary batteries, the high-nickel NCA positive electrode material of LiOH is used, the process is redesigned, residual lithium of the positive electrode material can be obviously reduced, the capacity is increased, expansion of the battery is reduced, and the safety of the battery is improved; and the structural stability of the material is effectively improved through a semi-doping semi-coating and Si coating method, the electrolyte erosion resistance of the material is improved, and the capacity and circulation of the battery are further increased.

Description

technical field [0001] The invention belongs to the technical field of positive electrode materials for non-aqueous electrolyte secondary batteries, and in particular relates to a preparation method of a half-doped, half-coated and Si-coated NCA positive electrode material. Background technique [0002] Due to the advantages of high energy density, small self-discharge, and good cycle performance, lithium-ion batteries are considered to be the most ideal energy storage devices in existing new energy vehicles. NCA cathode materials not only have high capacity and stable structure, but also have greatly improved safety. As we all know, Tesla has been using cylindrical batteries provided by Panasonic and LGC, which makes NCA attract more attention. However, due to the high content of Ni, the following problems occur in the use of NCA cathode materials: 1. Due to the strong oxidizing property of high-valent nickel, it is easy to have side reactions with the electrolyte, resulti...

AI Technical Summary

Problems solved by technology

However, due to the high content of Ni, the NCA cathode material has the following problems during use: 1. Due to the strong oxidizing property of high-valent nickel, it is easy to have side reactions with the electrolyte, resulting in metal dissolution

2. Due to the large amount of excess LiOH and Li on the surface and inside of the particles 2 CO 3 , it is easy to react with the electrolyte to release gas during the charge and discharge process, resulting in poor storage performance and thermal stability, and at the same time, due to the presence of excessive residual lithium impurities, the capacity loss is large

3. The nickel content is high, and there is a mixed cation phenomenon in the reaction process, which is easy to cause structural collapse during the charge and discharge process, affecting its capacity and cycle life

This invention has several disadvantages: first, more anion impurities are introduced when aluminum is added; second, organic solvents are used, which is not only dangerous to operate, but also uneconomical and environmentally friendly; third, the coating liquid is used The method of directly adding positive electrode material to dry in the medium does not effectively remove the high residual alkali in NCA

This invention has several disadvantages: first, more anion impurities are introduced when adding cobalt and aluminum; Because it increases the content of Co and Al in NCA, it has no practical effect; third, its calcination temperature is above 950 ° C, and the cation mixing is bound to be very serious, resulting in a decrease in capacity and cycle; fourth, the NCA ternary The cathode material precursor is dispersed in ethanol water solvent, using some organic solvents, which is not economical and environmentally friendly

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