Method for repairing waste lithium iron phosphate material

Abstract

The invention relates to a method for repairing a waste lithium iron phosphate material. The method comprises the following steps: 1) measuring the contents of Li, Fe and P elements in the waste lithium iron phosphate material; 2) preparing a mixed solution containing lithium salt, ferric salt and phosphoric acid, adding the waste lithium iron phosphate material into the mixed solution according to a final stoichiometric ratio of Li:Fe:P of 0.75-1.25:1:1, stirring and mixing the components, and controlling the pH value of the mixed solution to be 5.5-8.5 by using ammonia water in the stirringprocess to obtain a mixture; 3) carrying out hydrothermal reaction on the mixture at 100-200 DEG C to obtain a lithium iron phosphate precursor, and 4) carrying out carbon coating reaction on the lithium iron phosphate precursor at 650-800 DEG C to obtain the repaired lithium iron phosphate battery material. The method realizes direct repair of the waste lithium iron phosphate battery positive electrode material.

Description

technical field [0001] The invention relates to the fields of recovery of waste lithium ion batteries, hydrometallurgy, and resource recycling, and in particular to a method for repairing waste and old lithium iron phosphate materials. Background technique [0002] Automobile manufacturers mainly choose lithium iron phosphate batteries as power batteries. At present, the service life of lithium iron phosphate batteries is about 5 years. As a large number of lithium iron phosphate-powered electric vehicles are put into use, the amount of waste lithium iron phosphate batteries will also increase. Gradually increasing, it is estimated that by this year, the amount of waste lithium iron phosphate will reach 120,000 to 170,000 tons. It contains a large amount of lithium element, which is the main raw material for the production of lithium-ion power batteries, making its recycling very important for the development of lithium-ion power vehicles. At the same time, waste lithium ir...

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Problems solved by technology

[0003] The waste power lithium-ion battery recycling industry is mainly based on wet methods, which recover valuable metals in positive electrode materials, dissolve them with inorganic acids, extract and separate them to obtain metal compounds and sell them as products, as disclosed in Chinese patents CN201810592130.7 and CN201910711370.9 The leaching process is used to recover valuable metal elements such as lithium in lithium iron phosphate, but in this process, a large amount of acid and alkali consumption and subsequent treatment of environmental pollutants are very cumbersome

[0004] The recycling process of waste lithium iron phosphate cathode materials, that is, the reconstruction process of lithium iron phosphate crystals, is studied. The principle is that the cathode materials react with supplementary raw materials to repair the damaged lattice and re-form regular olivine-type phosphoric acid. Lithium iron crystals, such as Chinese patents CN201010253859.5 and CN201610623808.4, make the relevant elements exist in the form of ions through acid leaching, and then re-produce lithium iron phosphate materials through ball milling and calcination. The steps of this method are relatively lengthy and require high equipment.

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