Non-acid system liquid-phase synthesized C/metal solid solution/Ni<2+>, Cu<2+>-doped ZrF<4> positive electrode and preparation method

Abstract

The invention discloses a non-acid system liquid-phase synthesized C / metal solid solution / Ni<2+>, Cu<2+>-doped ZrF<4> composite zirconium fluoride lithium ion battery positive electrode material and a preparation method therefor. According to the preparation method, by virtue of design of a mixing way of reaction raw materials which comprise zirconium nitrate pentahydrate and ammonium fluoride, and an adding way and adding rate of water, addition of dilute nitric acid which suppresses hydrolysis can be avoided, so that risk of generating high-toxicity hydrogen fluoride by a reaction between dilute nitric acid and ammonium fluoride can be avoided; by means of generating cracking carbon in a heat treatment process and by performing in-situ reduction of a certain amount of metal solid solution on the surface of the zirconium fluoride granules in an in-situ manner, a homogeneous crystallization core can be provided for discharging of the electrode material and dynamic obstruction in new phase formation can be lowered; by virtue of Ni<2+>, Cu<2+> doped in the system, the rate of a discharging reaction can be improved; and meanwhile, generation of multiple kinds of compound salt of zirconium fluoride and other secondary reaction products in a liquid phase reaction can be avoided, and excellent electrochemical performance is achieved.

Description

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

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Problems solved by technology

The conventional synthesis method of zirconium fluoride is to react hydrogen fluoride gas with metal oxide / hydroxide or fluorine gas with 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.

The preparation of zirconium fluoride by liquid phase reaction is often unable to be used as a positive electrode material because the content of by-products is too high. At the same time, the dilute nitric acid added to inhibit the hydrolysis of zirconium nitrate in water has the risk of producing highly toxic hydrogen fluoride by reacting with ammonium fluoride.

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

Although some researchers have used carbon black mixed with ball milling to increase the electrical conductivity of the material, it is still difficult for granular carbon black to form a complete conductive link, which greatly improves its electronic conductivity.

Finally, the material produces a new phase of metal zirconium and lithium fluoride during discharge, and the small particles of the new phase are kinetically disadvantaged in the initial stage of formation, so the maintenance of the subsequent charge and discharge capacity, discharge potential, and charge and discharge capacity ability to adversely affect

Ion doping is also 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 difficult. expected

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