A solid phase synthesis al 3+ ,cu 2+ Doped cubic bismuth fluoride lithium ion battery positive electrode material and preparation method thereof

Abstract

The invention provides an Al<3+> and Cu<2+> doped cubic-structure bismuth fluoride lithium ion battery positive electrode material based on solid phase synthesis and a preparation method thereof. According to the method, a quaternary ammonium salt utilizing fluorine as negative ions is adopted as a raw material so as to directly synthesize cubic-structure bismuth fluoride by virtue of a large-group steric hindrance effect and the effect of a specific accessory ingredient in a solid phase manner; furthermore, Cu<2+> is doped, so that the average discharge electric potential of the raw material is improved; Al<3+> is doped, so that the capacity circulation stability is improved; serving as a lithium ion battery positive electrode material, the bismuth fluoride material has a specific capacity greater than 200mAh.g<-1>. The method is low in equipment requirement and high in product purity, and can be used for avoiding the problem that byproducts such as multiple complex salts of bismuth fluoride are generated during solid-phase reaction; the product has excellent electrochemical performance.

Description

technical field [0001] The invention relates to the technical field of a method for manufacturing a high-capacity bismuth fluoride composite lithium battery cathode material. Background technique [0002] Lithium-ion secondary batteries have the absolute advantages of high volume, weight-to-energy ratio, high voltage, low self-discharge rate, no memory effect, long cycle life, and high power density. Currently, the global mobile power market has an annual share of more than 30 billion US dollars and Gradually grow at a rate of more than 10%. Especially in recent years, with the gradual depletion of fossil energy, new energy sources such as solar energy, wind energy, and biomass energy have gradually become alternatives to traditional energy sources. Among them, wind energy and solar energy are intermittent, and a large amount of energy is used simultaneously to meet the needs of continuous power supply. Energy storage batteries; urban air quality problems caused by automobi...

AI Technical Summary

Problems solved by technology

The conventional synthesis method of bismuth fluoride is to react with hydrogen fluoride gas and metal oxide / hydroxide or fluorine gas and metal element at high temperature. The process conditions are harsh, the equipment requirements are very high, and the energy consumption is high, so the price is very expensive.

However, the preparation of bismuth fluoride by liquid phase reaction is often unable to be used as a positive electrode material because the by-product content is too high, and it is also uneconomical due to the high cost of waste liquid.

Bismuth fluoride, as a cathode material for lithium-ion secondary batteries, also has a negative characteristic that its electronic conductivity is extremely low, so it will cause a high polarization voltage during charge and discharge.

[0007] In addition, the crystal form and morphology of bismuth fluoride have a great influence on the electron transport characteristics in the crystal lattice, so it is directly related to the electrochemical performance of lithium ion batteries such as charge and discharge speed, capacity and cycle capacity retention; ion doping is a It is an effective way to adjust the microstructure of the lattice and change the electron and ion transport characteristics of the lattice. However, the mechanism of ion doping or even multi-ion synergistic doping on the matrix is ​​very complicated, and the effect is often unpredictable.

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