Method for preparing lithium iron manganese phosphate precursor and method for preparing lithium iron manganese phosphate

Abstract

The invention relates to a method for preparing a lithium iron manganese phosphate precursor and a method for preparing lithium iron manganese phosphate. The method for preparing the lithium iron manganese phosphate precursor comprises the following steps: (1) preparing a liquid material A and a liquid material B, wherein the liquid material A is a mixed solution of a manganese salt and an iron salt, and the liquid material B is an oxalic acid or phosphoric acid solution; (2) carrying out a coprecipitation reaction on the liquid material A and the liquid material B in a supergravity rotating bed to obtain a first slurry; (3) washing and filtering the first slurry to obtain a filter cake; (4) mixing the filter cake with water, adding a carbon source, and uniformly stirring to obtain a second slurry; (5) homogenizing the second slurry; and (6) drying the homogenized second slurry to obtain the lithium iron manganese phosphate precursor. The particle size of the lithium iron manganese phosphate precursor prepared by the method is smaller and more uniform than that of a precursor prepared by a traditional method using a reaction kettle, the preparation speed is increased, and carbon coating is uniform.

Description

technical field [0001] The invention belongs to the technical field of chemical crystallization, and in particular relates to a method for preparing nano-scale lithium manganese iron phosphate precursor ferromanganese oxalate or ferromanganese phosphate through a supergravity technology. [0002] technical background [0003] With the popularization of various electronic products and electric vehicles, people's requirements for battery capacity and electric vehicle cruising range are constantly increasing. Driven by this trend, high-nickel ternary cathode active materials will become an inevitable development direction. In the ternary positive electrode active material, the higher the nickel content, the higher the discharge specific capacity after the battery is assembled. But everything has two sides, and high-nickel ternary positive electrode active materials are not invulnerable. Many experts pointed out that the higher the nickel ratio, the worse the thermal stability ...

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Problems solved by technology

[0006] The second aspect is cost. Currently, the cost of ternary materials remains high, especially the price of high-nickel ternary positive electrode active material NCM811 is more than 100% higher than that of lithium manganese iron phosphate material.

[0007] The third aspect is battery life. Theoretically, the cycle life of ternary materials will gradually decrease with the increase of nickel content. At present, the life of high-nickel ternary materials is about 1200-1500 times, and it is not realized in the full discharge range. , so that the advantages of ternary high energy density are discounted

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