Polyphase manganese base solid solution composite cathode material and preparation method thereof

Abstract

The invention relates to a preparation method of polyphase manganese base solid solution composite cathode material, which is characterized in that manganese salt, nickel salt, cobalt salt and lithium salt are taken as raw materials, novel polyphase manganese base solid solution is prepared, and then nano highly-conductive graphene is composited on the surface of the novel polyphase manganese base solid solution, so that the polyphase manganese base solid solution composite cathode material is obtained. Compared with the prior art, the polyphase manganese base solid solution composite cathode material comprises three solid solution phases, namely, monoclinal layered Li2MnO3 with space group of C2 / m and rocking chair layered LiMn0.5-xNi0.5-xCo2xO2 with space group of R-3m and three-dimensional network structure high-voltage spinel LiMn1.5-xNi0.5-xCo2xO4 with space group of Fd3m, and through introducing the LiMn1.5-xNi0.5-xCo2xO4 phase and the graphene thin layer, the intrinsic electronic conductivity and ionic conductivity of the solid solution are obviously improved, the first irreversible capacity is reduced, and the low-temperature property and rate capability are obviously improved.

Description

technical field [0001] The invention relates to the field of positive electrode materials for lithium ion batteries, in particular, the invention relates to a multiphase manganese-based solid solution composite positive electrode material and a preparation method thereof. Background technique [0002] High specific energy and high specific power are the inevitable demand for lithium-ion batteries in the future market, and the development of lithium-ion battery cathode materials with high capacity and high rate performance is the key. LiCoO, a commercial cathode material for lithium-ion batteries 2 , LiMn 2 o 4 、LiFePO 4 The discharge specific capacity of these materials is below 200mAh / g, and their energy density is limited. Lithium-rich cathode materials, especially lithium-rich manganese-based cathode materials, have attracted widespread attention due to their ultra-high specific capacity and relatively low price. The currently reported lithium-rich manganese-based cat...

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Problems solved by technology

[0006] In view of the problems of low initial coulombic efficiency, poor rate and low-temperature performance of manganese-based solid solution materials in the prior art, one of the purposes of the present invention is to provide a lithium-ion battery with high capacity and initial efficiency, good rate and low-temperature performance Multiphase manganese-based solid solution composite cathode material, by introducing spinel LiMn with rich three-dimensional network structure 1.5-x Ni 0.5-x co 2x o 4 phase and highly conductive uniform graphene thin layer, significantly improving the intrinsic electronic conductivity and ionic conductivity of solid solution materials, effectively solving the above problems

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