Method for modifying surface of lithium cobalt oxide positive electrode material by phosphorus-containing compound and lithium cobalt oxide positive electrode material

Abstract

The invention provides a method for modifying the surface of a lithium cobalt oxide positive electrode material by a phosphorus-containing compound and the lithium cobalt oxide positive electrode material, and the method comprises the following steps: 1, by taking a lithium cobalt oxide powder material with a layered structure as a matrix, carrying out ball-milling mixing on the lithium cobalt oxide powder material and the phosphorus-containing compound according to a certain proportion to obtain a mixed powder material; 2, in an atmosphere protection environment, heating the mixed powder material to obtain the modified lithium cobalt oxide positive electrode material, wherein the interior of which is lithium cobalt oxide, the near surface of which comprises lithium cobalt oxide crystal lattices and phosphate radical bonds and the surface of which comprises an amorphous coating layer composed of metal ions and phosphate radical groups. According to the preparation method, a phosphorus-containing compound and lithium cobalt oxide are mixed and heated for process control and treatment, so the surfaces of lithium cobalt oxide particles are modified, and the stability of a lithium cobalt oxide structure is enhanced by doping phosphate radicals in surface crystal lattices; and the amorphous coating layer effectively protects the electrode electrolyte interface, reduces the interfaceside reaction, and improves the rate capability and the 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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