Boron-doped lithium phosphate coated lithium ion battery positive electrode material and preparation method thereof

Abstract

The invention discloses a boron-doped lithium phosphate coated lithium ion battery positive electrode material, which takes a layered structure oxide with high nickel content as a matrix, and the outer surface of the matrix is coated with a boron-doped Li3PO4 coating layer. The preparation method comprises the following steps: (1), adding a lithium source, a phosphorus source and a boron source into a high-pressure reaction kettle for hydrothermal reaction, and after the reaction is finished, performing cooling, washing, filtering and drying to obtain a coating agent; and (2), weighing a basematerial and the coating agent according to a stoichiometric ratio, uniformly performing mixing, and performing sintering to obtain the boron-doped lithium phosphate coated lithium ion battery positive electrode material. By introducing a proper amount of boron into the lithium phosphate coating layer of the lithium ion battery positive electrode material, the lithium ion conduction capability ofthe lithium ion battery positive electrode material is effectively improved, so that the positive electrode material coated with the coating layer shows relatively good capacity and rate capability and has a relatively low DCIR growth rate.

Description

technical field [0001] The invention belongs to the field of lithium-ion battery cathode materials, in particular to a boron-doped lithium phosphate-coated lithium-ion battery cathode material and a preparation method thereof. Background technique [0002] Ternary lithium transition metal oxides (LiTMO) with high nickel content 2 ) cathode material has a high specific capacity (≥200mAh / g), which can meet the high energy density requirements of lithium-ion batteries for electric vehicles, and has become one of the current research hotspots. However, high-nickel cathode materials are also accompanied by problems such as unstable bulk phase structure and increased surface side reactions, which make the performance of the battery such as cycle, high temperature, storage, and gas production unsatisfactory. Surface coating and modification can prevent the fragile high-nickel cathode material from being in direct contact with the electrolyte, avoiding decomposition and oxidation o...

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Problems solved by technology

[0004] (1) The wet coating process is complicated, and the organic system coating has production safety risks, which is not conducive to the batch industrialization of materials;

[0005] (2) Wet coating needs to add an additional lithium source, which is not conducive to the control of residual lithium in the finished material, and the precipitation speed and reaction degree of lithium phosphate are also relatively insufficient;

[0006] (3) Single Li 3 PO 4 The lithium ion conduction ability of the coating is insufficient, and the coating effect needs to be further improved

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