Preparation method of ferric phosphate

Abstract

The invention provides a preparation method of ferric phosphate. The preparation method comprises the following steps of: firstly adding acid to a ferrous salt solution to regulate a pH value; then uniformly mixing with a phosphate solution or/and a mixture of phosphoric acid and a phosphate; then adding an oxidizing agent to react to generate ferric phosphate. The preparation method of ferric phosphate, disclosed by the invention, well overcomes the defects of the traditional preparation method of ferric phosphate; the pH of an iron source is regulated before the iron source and a phosphorus source are mixed, so that a pre-estimated pH range can be reached without adding a pH regulating agent after the mixing, and the problem that impurities, such as Fe(OH)3, are generated because the alkaline pH regulating agent is locally excessive in the traditional method is prevented; no iron hydroxide is generated in the technical process, the obtained ferric phosphate is high in purity; high-quality ferric phosphate can be obtained after impurity ions are further removed subsequently, the purity exceeds 99.8%, the iron content is stabilized at 36.8%-37.2%, and the phosphate radical content is stabilized at 62.8%-63.2%.

Description

technical field [0001] The invention relates to a method for preparing iron phosphate, and the prepared material is mainly used for making battery materials. Background technique [0002] As a precursor of lithium iron phosphate, the positive electrode material of batteries, iron phosphate has obvious advantages and its usage continues to expand. The traditional method for preparing battery-grade iron phosphate is to use Fe 2+ After salt solution oxidation or directly with Fe 3+ The solution is mixed with phosphate, the pH of the solution is adjusted, a precipitate is formed, and the ferric phosphate product is obtained by washing, filtering and drying. In most of these preparation methods, when the pH regulator is mixed with iron phosphate, an irreversible side reaction occurs to generate hydroxide precipitation. As everyone knows, iron hydroxide is a typical hard-to-filter colloid, which endangers the quality of iron phosphate. After processing this type of iron phospha...

AI Technical Summary

Problems solved by technology

In most of these preparation methods, when the pH regulator is mixed with iron phosphate, an irreversible side reaction occurs to generate hydroxide precipitation. As everyone knows, iron hydroxide is a typical hard-to-filter colloid, which endangers the quality of iron phosphate. After processing this type of iron phosphate into lithium iron phosphate batteries, there are generally problems such as low capacity and large self-discharge.

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