Method for preparing ferric pyrophosphate used for lithium ion battery by utilizing iron-bearing raffinate

Abstract

The invention relates to a method for preparing ferric pyrophosphate used for a lithium ion battery by utilizing iron-bearing raffinate. The method comprises the following steps of (1) adding oxidizing agent solution in the iron-bearing raffinate, stirring, adding the raffinate to carry out multistage extraction, and washing a separated organic phase through inorganic acid to obtain ferric salt solution; and (2) taking the ferric salt solution in the step (1) as an iron source, adding a phosphorus source, stirring, adding a pH regulator to react, cooling, carrying out solid-liquid separation, washing and drying to obtain a battery-level ferric pyrophosphate powder material. According to the method, the ferric salt solution recycled from the iron-bearing raffinate is taken as the iron source to prepare ferric pyrophosphate, so that the scrap metallic iron is recycled to the greatest extent, the economic benefit is improved, the environmental pollution is reduced; the whole preparation process is greatly simplified, and the production cost is reduced.

Description

technical field [0001] The invention relates to the field of lithium-ion battery materials, in particular to a method for iron orthophosphate for lithium-ion batteries, and in particular to a method for preparing iron orthophosphate for lithium-ion batteries by using iron elements recovered from iron-containing raffinate as an iron source method Background technique [0002] Since iron orthophosphate (FePO 4 ) has a rich chemical structure and has a wide range of applications in the fields of lithium-ion battery materials, catalysis, ceramic glass, and agriculture. After market selection and development of R&D technology, lithium iron phosphate (LiFePO 4 ) The mainstream preparation process has gradually shifted from the ferrous oxalate process to the iron phosphate process. The lithium iron phosphate material produced by this method usually has better performance and is suitable for the preparation of high-end lithium battery products. The synthesis process has the follo...

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Problems solved by technology

[0003] The raw material of industrial production iron phosphate usually comprises iron source, phosphorus source, oxidizing agent and lye, iron source usually adopts ferric salt or ferrous salt at present, and the iron source disclosed as CN102491302A and CN102555725B is ferrous sulfate (FeSO 4 ), ferrous chloride (FeCl 2 ), ferric nitrate (FeNO 3 ) and ferric chloride (FeCl 3 ), etc., by adding an oxidant to oxidize the ferrous salt to ferric salt, the disadvantage of this method is the use of non-renewable resources, and the use of ferric salt, oxidant and lye increases the production cost of ferric phosphate

CN104409732A discloses a preparation method of a lithium iron phosphate material using a mixed iron source, which uses a certain proportion of ferric oxide and iron orthophosphate to prepare lithium iron phosphate, which reduces the cost of raw materials, and the prepared lithium iron phosphate positive electrode active material When used as a lithium-ion cathode material, it maintains good processability and other characteristics, but it still has the defect of high cost

However, the extraction of this ferrous salt solution is relatively rough, there are still a lot of impurities in it, and the concentration of active ingredients is low

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