Anion and cation compound doping spinel lithium manganate and preparation method thereof

Abstract

The invention provides anion-cation compound-doped spinel lithium manganese. A molecular formula of the anion-cation compound-doped spinel lithium manganese is represented as LiMn<2-x>(M)<x>O<4-y>(N)<y>, wherein M and N represent doped cations and anions respectively; and the cations and the anions enter spinel lattices of spinel lithium manganese to form a stable spinel single-phase compound. The preparation method comprises the following steps of firstly, fully grinding and evenly mixing a manganese source, a lithium source, a cation material and an anion material to obtain a lithium manganese oxide-doped mixture; adding an organic solvent to adjust into paste, fully mixing the paste, pre-sintering for several hours, carrying out cooling and grinding, gradually warming a pre-sintered product by stages again for multi-step sintering and slowly cooling the obtained pre-sintered product; and finally crushing and screening the pre-sintered product to obtain the anion-cation compound-doped spinel lithium manganese. The product provided by the invention has relatively high initial discharge specific capacity and also has excellent charge-discharge cycle performance and high temperature performance.

Description

Technical field [0001] The present invention is a lithium ion battery positive electrode material and a preparation method thereof, in particular to a positive electrode material lithium manganate and a preparation method thereof. Background technique [0002] With the continuous development of the economy, people are paying more and more attention to energy issues. The soaring oil price has made people have a deeper understanding of new energy, especially the 2008 national "863 Program" modern transportation technology field "energy saving and new energy vehicles" important The project uses lithium manganate cathode material as the preferred material for power batteries, and lithium ion battery materials face a development opportunity. Represented by electric vehicle power batteries, the field of lithium-ion batteries is taking shape. The current commercial lithium-ion cathode materials are mainly lithium cobalt oxide, which is relatively mature in technology and has the best e...

AI Technical Summary

Problems solved by technology

Spinel lithium manganese oxide has the advantages of low cost, easy synthesis, high working voltage, high safety performance, no pollution to the environment, and high capacity. It is considered to be the most likely substitute for lithium cobalt oxide and has the greatest application potential. However, the capacity fading and poor electrochemical performance of lithium manganate have always been the bottlenecks that limit its application. The Jahn-Teller distortion effect and the dissolution of manganese have not been well resolved.

[0004] According to the comprehensive literature, the synthesis methods of spinel lithium manganese oxide mainly include the following types: (1) High temperature synthesis method: mix lithium hydroxide and manganese oxide, and calcinate at high temperature for several hours to obtain Lithium manganate; (2) Melt impregnation method: using LiNO with a lower melting point 3 As a lithium source, pre-treatment is carried out at about the melting point of lithium salt, and then the lithium source is impregnated into the porous surface of manganese dioxide to increase the contact of reactants and improve the reaction efficiency. The synthesized lithium manganate has excellent electrochemical properties; (3 ) Sol-gel method: This method is to form a chelate with metal ions and organic acids, then esterify and further polymerize into a polymer to prepare a precursor, and finally roast the precursor to obtain lithium manganate, but the initial discharge capacity of the product Low, at the same time a large amount of organic solvents, difficult to recycle, high cost, the preparation process needs to be improved; (4) co-precipitation method: by adjusting the pH value of the solution to co-precipitate lithium ions and manganese ions, so that lithium and manganese are mixed at the atomic level , to prepare lithium manganate, but the process is complicated, and it needs to go through steps such as filtration, washing and drying, and the performance of the positive electrode material is not ideal

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