Process for reducing impacts on LixFeyPzO4 caused by impurity elements in ferrophosphorus

Abstract

The invention relates to a process for reducing the impacts on LixFeyPzO4 caused by impurity elements in ferrophosphorus, which belongs to the field of material chemical industry. The process comprises the following steps: firstly dissolving and filtering products of the ferrophosphorus and lithium salt under the oxidative atmosphere, then obtaining Li3PO4 filtrate and a Fe2O3 filter cake, carrying out concentration and granulation on the filtrate for obtaining high purity spherical Li3PO4, carrying out acid dissolution, filtration and reaction with phosphoric acid or phosphate on the filter cake, then controlling the temperature and the pH value for obtaining FePO4 precipitate, filtering, washing and drying for obtaining high purity FePO4, finally mixing the Li3PO4, the FePO4 and supplementary raw materials, then carrying out reaction under the non-oxidizing atmosphere for obtaining LixFeyPzO4. The method can reduce the impurity elements in the ferrophosphorus, simplify the control of oxygen content and improve the tap density of the product, and the ferrophosphorus can replace carbon.

Description

technical field [0001] The invention relates to a method for reducing the impurity elements of phosphorus and iron to Li x Fe y P z o 4 Influenced process, which can be applied to the purification of ferrophosphorus recycling process and high-performance electrode material Li x Fe y P z o 4 low-cost development. Background technique [0002] Li x Fe y P z o 4 It is a new type of green energy electrode material with great potential, mainly including LiFePO 4 , LiFe 2 / 3 PO 4 and Li 4 / 7 Fe 4 / 7 P 8 / 7 o 4 And its compound, the market space is broad. Among these electrode materials, LiFePO 4 Due to its unique structure and performance, it has attracted much attention, but the current high preparation cost hinders its large-scale application in power batteries, and people have tried various ways to reduce costs and improve performance. However, due to the bottleneck of the process route and raw materials, the commercial LiFePO on the market 4 It needs to be car...

AI Technical Summary

Problems solved by technology

Currently commercial Li x Fe y P z o 4 A major problem that still exists in the preparation process of the method is: adopt the salt containing a kind of metal or metal simple substance to make reactant, adopt unstable ferrous salt as raw material, provide protective atmosphere with argon, nitrogen, hydrogen or C, to The limit of oxygen amount is relatively strict. Oxygen is not used as the reaction raw material. In addition, other elements are deliberately added to dope and modify to improve performance. The cost of raw materials and preparation is high, and the tap density of the material is low.

These impurity elements may affect the electrochemical performance of the material. At present, they are mostly purified by mechanical treatment, regional melting, recrystallization, etc., which need to be completed under an inert atmosphere at a higher temperature. The process is more complicated and the cost of impurity removal is higher.

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