Bi<3+>,B<3+> doped copper fluoride positive electrode material coated by gradient structure and used for lithium battery and preparation method thereof

Abstract

The invention provides a Bi<3+>,B<3+> doped copper fluoride positive electrode material gradiently coated by Bi2O3 / BiF3-2xOx and used for a lithium battery, and a preparation method thereof. According to the method, Bi<3+>,B<3+> doped copper fluoride is prepared through solid-phase synthesis; then on the basis of the characteristic that BiF3 is prone to gradual oxidation into Bi2O3 at a high temperature, BiF3-2xOx (wherein 0<x<0.3) and a Bi2O3 layer successively coat Bi<3+>,B<3+> doped copper fluoride particles so as to improve surface electron conduction capability of Bi<3+>,B<3+> doped copper fluoride and to resist harmful effect of an organic electrolyte on particle surfaces; and comprehensive electrochemical performance of copper fluoride is greatly improved through Bi<3+>,B<3+> doping.

Description

technical field [0001] The invention relates to the technical field of a method for manufacturing a high-performance copper 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 automo...

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Problems solved by technology

However, there are very few reports about copper fluoride materials as lithium-ion battery cathode materials. The main difficulty is that the electrochemical performance of copper fluoride is very sensitive to crystal water. If there is a trace of crystal water in the crystal, the electrochemical performance will be reduced There is serious attenuation; and the copper fluoride material is very easy to absorb water in the air, and at the same time it is very easy to form crystal water during the preparation process, so it is difficult to prepare and store

At the same time, the copper fluoride material is not stable enough in the organic electrolyte, and it has a negative characteristic that the electronic conductivity is extremely low, so it will cause a high polarization voltage during the charge and discharge process.

Generally, surface coating modification and ion doping are effective means to adjust the surface microstructure and change the electronic and ion transport characteristics of materials, which may improve the electrochemical performance of materials, and are also a means of stabilizing the surface characteristics of material particles. However, after many cycles of battery materials, due to the lattice mismatch between the coating material and the parent material and the volume change of the parent material during the cycle, the coating material is often detached from the parent material and fails.

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