Method for controlling shape and carbon content of iron phosphate material

Abstract

The invention discloses a method for controlling the shape and the carbon content of an iron phosphate material. The method comprises the steps of: mixing to prepare a raw material of the iron phosphate material, presintering, and then drying to obtain powder of a precursor of the iron phosphate material; smashing the presintered and dried powder of the precursor of the iron phosphate material; detecting the carbon content of the smashed powder, and placing the powder of the measured batch to a ball mill to be subjected to ball-mill and reshaping treatment when the carbon content of the powder of the measured batch is within a control valve range and balancing and mixing the powder batches with positive deviation and negative deviation calculated according to weight percentage when the carbon content of the powder of the measured batch is beyond the control value range and has deviation, and then placing the mixture into the ball mill to be subjected to ball-mill and reshaping treatment; detecting the grain size of the powder subjected to ball-mill and reshaping treatment, and discharging when the grain size of powder of the measured batch meets the requirement of the control value; and performing secondary sintering to obtain the finished product of the iron phosphate material.

Description

technical field [0001] The invention belongs to the technical field of energy material manufacturing, and in particular relates to a method for controlling the morphology and carbon content of the lithium iron phosphate material during the manufacturing process of the lithium iron phosphate material. Background technique [0002] Lithium-ion batteries have become the main choice of rechargeable power supplies for today's portable products because of their advantages such as large specific energy, high power density, long cycle life, low self-discharge, high performance-price ratio, and less pollution. With the development of lithium-ion batteries, cathode materials have become one of the important bottlenecks restricting the development of lithium-ion batteries. Due to the existence of mixed valence states, transition metals often have relatively ideal electronic conductivity and are not prone to disproportionation reactions. Their oxides have become the first choice for lit...

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Problems solved by technology

[0003] At present, in the production of lithium iron phosphate materials, the raw materials are generally crushed after pre-calcination. Large, general processing performance, large dispersion of chemical performance indicators of materials

At the same time, the coated carbon source and reduced carbon source used in the production process of lithium iron phosphate materials are mainly organic carbon sources, and the discrete medium used is mainly industrial alcohol, so there are differences in the production process of carbon-coated lithium iron phosphate materials. The carbon content deviation of different batches of materials is relatively large. At present, the deviation of carbon content between different batches of international and domestic lithium iron phosphate materials is ±0.3%. These deviations are mainly caused by the mixing and ball milling in the production process. It is difficult to control the degree of dryness to be completely consistent, and the industrial alcohol used as a dispersion medium contains higher alcohols

The direct consequence of the carbon content deviation of this material is the deviation of the tap density and specific surface area of ​​each batch of materials, that is, the deviation of electrochemical performance and processing performance, which also affects the batches of iron phosphate we produce. The consistency of lithium materials has a greater impact on subsequent battery manufacturing

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