Synthesis method of silicon dioxide coated lithium-rich manganese-based cathode material

Abstract

The invention discloses a synthesis method of a silicon dioxide coated lithium-rich manganese-based cathode material, belonging to the technical field of cathode materials of lithium ion batteries. The synthesis method is realized mainly in the following way: the surfaces of the lithium-rich manganese-based cathode material and precursor thereof are coated with silicon dioxide through the hydrolysis of tetraethyl orthosilicate; by controlling the dispersing agent composition and reaction temperature, a uniform and dense coating layer with controllable thickness can be formed on the material surface by the synthesis method; and the uniform and controllable coating layer can effectively separate electrode from electrolyte, the decomposition of electrolyte is inhibited, the HF generated by LiPF6 decomposition is absorbed, and the electrochemical performance and particularly the rate performance, high-temperature performance and safety performance of the lithium-rich manganese-based cathode material are improved. The synthesis method has the advantages of easily available raw materials, simplicity in operation, mild conditions and environment-friendly and recyclable dispersing agents while industrial production is facilitated.

Description

technical field [0001] The invention relates to a method for synthesizing silicon dioxide-coated lithium-rich manganese-based positive electrode materials, and belongs to the technical field of lithium ion battery positive electrode materials. Background technique [0002] As the energy density of lithium-ion batteries is further improved and the cost is further reduced, its application fields have expanded from small electrical equipment such as notebook computers and mobile phones, especially in the fields of new energy vehicles and energy storage in recent years. As the upstream of the new energy vehicle industry chain, the energy density, service life, safety, cost and production capacity of power lithium batteries directly affect the scale of the new energy vehicle industry. Same as the commercialized LiMn 2 o 4 、LiCoO 2 、LiFePO 4 Compared with lithium-rich manganese-based cathode materials xLi 2 MnO 3 ·(1-x)LiMO 2 (M is one or more of the transition metal elemen...

AI Technical Summary

Problems solved by technology

[0003] The electrolyte of lithium-ion batteries uses a mixed system of lithium salts and organic solvents. Under the high operating voltage of lithium-rich manganese-based positive electrode materials, an electrode-electrolyte interface reaction will occur to decompose the organic solvent and form a gradually growing solid electrolyte film ( SEI film), as a class of non-Li + conductor, covering the surface of the material slows down the Li + The deintercalation rate of the material leads to a decrease in the rate capability of the material

And with LiPF 6 In the electrolyte as a lithium salt, in the presence of a small amount of water, LiPF 6 Decomposition produces HF, which corrodes the electrode surface of lithium-rich manganese-based positive electrode materials, causing the dissolution and precipitation of manganese elements from the bulk phase of the material, resulting in a decrease in battery cycle stability; HF will also accelerate electrode-electrolyte side reactions, and even precipitate CO 2 and other gases, causing the battery to swell and reducing the safety performance of lithium-ion batteries

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