Preparation method of polyelectrolyte-cladding LiNixCoyMn<1-x-y>O2 positive electrode material

Abstract

The invention discloses a preparation method of a polyelectrolyte-cladding LiNixCoyMn<1-x-y>O2 positive electrode material. The method is characterized in that the cladding treatment is carried out by cutting the polyelectrolyte solution at high speed, then the polyelectrolyte solution is dried to obtain the polyelectrolyte-cladding LiNixCoyMn<1-x-y>O2 positive electrode material, and the polyelectrolyte is one or a mixture of more of lithium polyacrylate, lithium polymethacrylate, lithium polymaleic anhydride, poly (methyl vinyl ether copolymer maleic acid) lithium or lithium polyfumarate. The cladding method is characterized in that a layer of polyelectrolyte membrane is formed on the surface of the LiNixCoyMn<1-x-y>O2, so that the compatibility between the LiNixCoyMn<1-x-y>O2 and the electrolyte is improved, and the LiNixCoyMn<1-x-y>O2 has the characteristics of high specific capacity, high multiplying powder and long service life.

Description

technical field [0001] The invention relates to a preparation method of a high-voltage positive electrode material of a lithium ion battery, in particular to a preparation method of a high voltage nickel-cobalt lithium manganese oxide positive electrode material coated on the surface, and belongs to the technical field of lithium ion battery positive electrode materials. Background technique [0002] The ternary lithium nickel-cobalt-manganese (NCM) material has attracted widespread attention due to its high capacity (up to 250 mAh / g, 91% of the theoretical capacity), good safety, and low price. However, due to the existence of high-valent nickel during the charge and discharge process, the surface structure of the ternary lithium nickel cobalt manganese material is unstable, and it is easily corroded by HF in the electrolyte during the high voltage charge and discharge process, which makes the capacity decay faster, limiting for its use at high voltages. At present, the ma...

AI Technical Summary

Problems solved by technology

However, due to the existence of high-valent nickel during the charge and discharge process, the surface structure of the ternary lithium nickel cobalt manganese material is unstable, and it is easily corroded by HF in the electrolyte during the high voltage charge and discharge process, which makes the capacity decay faster, limiting for its use at high voltage

At present, the main method to solve these problems is to coat the surface of ternary lithium nickel cobalt manganese, which can effectively alleviate the dissolution of metal ions; at the same time, reduce the corrosion of active substances by HF, thereby effectively improving circulation, high temperature storage and safety. Performance. At present, the coating of ternary materials is mainly coated with metal organic salts such as Al, C, and Co. However, there is an obvious defect in this coating. Metal ions are exposed on the surface and are easy to dissolve, resulting in a decrease in cycle performance. ; At the same time, in the whole coating process, water is used as a solvent, which leads to the deterioration of the surface of the ternary lithium nickel cobalt manganese, further deteriorating the cycle performance

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