Lithium ion battery anode material adopting in-situ developed heterogeneous core-shell structure and preparation method of material

Abstract

The invention provides a lithium ion battery anode material adopting an in-situ developed heterogeneous core-shell structure and a preparation method of the material. The lithium ion battery anode material is a composite with a lithium-rich lamellar phase material as a core layer and a heterogeneous spinel phase generated on the surface of the core layer in an in-situ manner. The lithium ion battery anode material is prepared in the steps as follows the lithium-rich lamellar phase material containing Ni, Mn and M is prepared from carbonate or hydroxides with a coprecipitation method and then dispersed in a mixed salt solution of Ni, Mn and M, the amount-of-substance ratio of Ni to Mn to M in the solution is the same with that in the lithium-rich lamellar phase material, the coprecipitation reaction is performed again, and the mixed metal carbonate (or metal hydroxide) coated lithium-rich lamellar phase material is obtained, the lithium-rich lamellar phase material is sintered at the high temperature in the absence of a Li source, and the lithium ion battery anode material adopting the in-situ developed heterogeneous core-shell structure can be obtained. The lithium ion battery anode material adopting the in-situ developed heterogeneous core-shell structure has the advantages as follows the shell layer coats the core layer in a uniform, complete and thickness-controllable manner, no obvious phase boundaries exist between the core layer and the shell layer, and the electrochemical performance of the material is improved.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion battery cathode materials, in particular to a preparation method of a lithium-ion battery cathode material with a core-shell structure. Background technique [0002] At present, lithium-ion batteries have been widely used in various mobile appliances, such as mobile phones, cameras, and notebook computers. Cathode materials are an important part of lithium-ion batteries, and the development of high-energy-density cathode materials for lithium-ion batteries has become a research hotspot. [0003] Composite materials of layered Li-rich layered phases and spinel phases have been extensively studied in recent years. J.PowerSources,2013,240:193. reported a method for preparing lithium-rich layered phase and spinel phase composite materials: first prepare the hydroxide co-precipitation precursor of Ni and Mn, and then mix It is mixed and roasted with lithium salt to obtain a composite material wit...

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Problems solved by technology

Adv.Mater.,2013,25:3722 reported a method of coating spinel materials on the surface of lithium-rich layered materials: first, the surface of lithium-rich layered materials is coated with a layer of manganese salt, and then co-fused by roasting A method for forming a spinel phase on the surface and then preparing a spinel-coated lithium-rich layered material, but the transition between the spinel phase and the lithium-rich layered phase of the composite material prepared by this method Different proportions of metal elements are not conducive to the formation of a two-phase composite material with a stable structure and a controllable thickness of the core-shell structure

Phys.Chem.Chem.Phys., 2015, 17:1257 also proposed a method for coating lithium-rich layered materials with spinel phase: according to the spinel material LiNi 0.5 mn 1.5 o 4 The stoichiometric ratio of Li, Ni and Mn acetate solution was prepared, the layered lithium-rich material was dispersed in it, the solvent was evaporated to dryness and then roasted to form spinel phase material on the surface of the material, so as to obtain the designed sharp Lithium-rich layered phase material coated with spar, there is an obvious phase boundary between the spinel shell layer and lithium-rich layered core layer formed by adding lithium salt on the surface of the material, large interface impedance, and in During the cycling process, due to the difference in the expansion rate of the two phases, the separation of the core layer and the shell layer is easy to occur, which affects the electrochemical performance of the material.

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