Core-shell structure positive electrode material and preparation method thereof

Abstract

The invention provides a high-performance core-shell structure positive electrode material and a preparation method thereof. The preparation method comprises the following specific steps: (1) preparing a mixed solution A and a mixed solution B of nickel, cobalt and manganese salts with different molar components, and independently preparing a salt solution containing an X element; (2) respectively and simultaneously adding the solution A, an alkali solution and a complexing agent solution into a reaction kettle, and carrying out coprecipitation reaction to obtain an inner core; (3) adding the X salt solution and a precipitator solution to obtain an inner core with a coating layer; (4) adding the solution B, the alkali solution and the complexing agent solution into the base solution of the inner core with the coating layer to obtain a core-shell precursor with an interlayer; and (5) roasting to obtain the core-shell positive electrode material. According to the core-shell positive electrode material disclosed by the invention, due to the existence of the interlayer, a gap generated due to different volume changes of the inner core and the outer shell can be overcome, so that the connection force between the outer shell and the inner core is enhanced, and compared with a common core-shell positive electrode material, the core-shell positive electrode material has relatively excellent thermal stability and relatively long cycle performance.

Description

technical field [0001] The invention relates to the field of lithium ion battery materials, in particular to a positive electrode material with a core-shell structure and a preparation method thereof. Background technique [0002] In recent years, lithium-ion batteries have also been used in electric vehicles as a power source, which has become a new trend in the development of new energy vehicles. For lithium-ion batteries used in electric vehicles, consumers are more concerned about their cruising range, service life, acceleration performance, etc. These aspects largely depend on the performance of the power lithium-ion batteries used. [0003] One of the core links in the lithium-ion battery industry is the manufacture of cathode materials, and the performance of cathode materials largely determines the performance of lithium-ion batteries. Relevant enterprises and scientific research institutions have done a lot of research work on the morphology and structure of cathod...

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Problems solved by technology

[0005] However, in actual use, it is found that during the long-cycle charge-discharge process, irregular gaps or holes will appear at the interface between the core and the shell of the core-shell cathode material. The volume change during charge and discharge is inconsistent, and the irreversible change in volume leads to the appearance of this defect, which hinders the conduction of lithium ions to a certain extent, is not conducive to long-life cycle stability, and directly leads to Poor material cycle performance

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