Preparation method of composite structure iron orthophosphate for high capacity and high compacted lithium iron phosphate

Abstract

The invention discloses a preparation method of high-capacity and high-compactness composite-structure ferric phosphate for lithium iron phosphate, and relates to the technical field of lithium ion batteries. The preparation method comprises the following steps: 1) preparing a sulfuric acid solution, a phosphoric acid solution and a hydrogen peroxide solution; 2) adding deionized water into an iron source with stirring, adding a sulfuric acid solution with stirring, and adding a complexing agent to obtain a ferrous sulfate solution; 3) adding a phosphoric acid solution into the ferrous sulfatesolution with stirring, adding sodium carbonate or ammonia, adding a template agent and a hydrogen peroxide solution, stirring the mixture and carrying out aging treatment, then performing suction filtration, washing, drying and calcination on the reaction product. The iron phosphate hydrate precursor is synthesized through the coprecipitation method, and the appearance and the particle size distribution of iron phosphate are effectively controlled by controlling the feeding rate, the stirring frequency, the stirring time and the reaction temperature; therefore, the ferric phosphate with different morphologies, wide particle size distribution range and sheet-shaped and particle-shaped composite structures is obtained.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a method for preparing iron orthophosphate with a composite structure for high-capacity and high-pressure compacted lithium iron phosphate. Background technique [0002] With the wide application of lithium iron phosphate lithium ion batteries in new energy vehicles, wind energy storage, communication base stations, large database storage and other industries, the production and manufacturing of lithium iron phosphate cathode materials have also been vigorously developed. There are a variety of technological routes for the preparation of lithium iron phosphate cathode materials, and the technical routes that have been industrialized include iron oxide red route, oxalate ferrous route, hydrothermal synthesis route, and orthophosphate iron route. After industry and market practice and verification, the lithium iron phosphate prepared by the orthophosphate railway line...

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Problems solved by technology

[0004] Domestic ferric orthophosphate technology is based on the early low-level ceramic-grade and food-grade product models, which have problems of fluctuating purity and unclear crystal structure, and many manufacturers are out of touch with the preparation of positive electrode materials in the stage of product and technology development. It can solve the defects of low compaction density, low tap density and high specific surface area of ​​lithium iron phosphate from the source, which lead to poor processing effect

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