Method for surface modification of lithium cobaltate positive electrode material by phosphorus compound and lithium cobaltate positive electrode material

Abstract

The invention provides a method for modifying the surface of a lithium cobaltate positive electrode material with a phosphorus-containing compound and the lithium cobaltate positive electrode material, comprising the following steps: step 1, using a layered lithium cobaltate powder material as a matrix, and Compounds are ball milled and mixed according to a certain ratio to obtain a mixed powder material; step 2, heat the mixed powder material in an atmosphere protection environment to obtain a modified lithium cobaltate positive electrode material, the interior of which is lithium cobaltate, and the near surface Including lithium cobalt oxide lattice and phosphate root to form a bond, the surface includes an amorphous coating layer composed of metal ions and phosphate groups. The invention adopts process control and treatment of mixing and heating the phosphorus-containing compound and lithium cobaltate to modify the surface of lithium cobaltate particles, and utilizes the doping of phosphate on the surface lattice to enhance the stability of lithium cobaltate structure ; and effectively protect the electrode electrolyte interface by containing an amorphous coating layer, reduce interface side reactions, and improve rate performance and cycle performance.

Description

technical field [0001] The invention relates to the technical field of lithium cobaltate positive electrode materials, in particular to a method for modifying the surface of lithium cobaltate positive electrode materials with phosphorus compounds and the lithium cobaltate positive electrode materials. Background technique [0002] Lithium cobalt oxide cathode material is an ideal cathode material for lithium-ion batteries in the future. Increasing the working voltage of lithium cobalt oxide can provide higher specific capacity and energy density. However, when the charging voltage reaches 4.5V and above, lithium cobalt oxide faces, such as the irreversibility of the phase transition decreases, the particles undergo c-axis shrinkage greater than 3%, the release of lattice oxygen causes the destruction of the material structure, the phase transition of the interface, A series of problems such as the dissolution of transition metals lead to a decline in its cycle stability. ...

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Problems solved by technology

[0004] However, the current process of making the cladding layer is usually very complicated, and it is difficult to control the process control

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