Regeneration method for positive electrode material of waste lithium iron phosphate battery

Abstract

The invention provides a regeneration method for a positive electrode material of a waste lithium iron phosphate battery. The method comprises the following steps: carrying out discharge treatment onthe waste lithium ion battery, performing crushing and disassembling, separating out lithium iron phosphate positive electrode powder, mixing the lithium iron phosphate positive electrode powder witha hydrogen peroxide solution, leaching Li+, and introducing CO2 to control the pH value of the mixed solution, thereby obtaining a mixed solution A containing lithium salt and iron phosphate; measuring the ratio of lithium, iron and phosphorus in the mixed solution A, adding a lithium source, an iron source or a phosphorus source to enable the molar ratio of Li + to Fe3+ to PO43- to be (1-1.05): 1: 1, and adding a carbon source to enable the carbon content of the lithium iron phosphate product to be controlled to be 1%-10% to obtain a mixed solution B; and carrying out spray pyrolysis on the mixed solution B under a certain temperature condition and an inert gas atmosphere to obtain the carbon-coated lithium iron phosphate material. The method has the advantages of simple process, short flow, no introduction of impurity elements, mild reaction, high leaching efficiency, low cost and recyclable resources; the discharged waste gas is mainly CO2, and the method is green and environment-friendly and is beneficial to industrial large-scale production.

Description

technical field [0001] The invention belongs to the technical field of recycling waste lithium ion batteries, and in particular relates to a method for regenerating positive electrode materials of waste lithium iron phosphate batteries. Background technique [0002] With the advancement of new energy product technology, especially the demand for lithium-ion batteries in the electronic market and electric vehicle market is increasing year by year. As of the end of 2017, my country has promoted more than 1.8 million new energy vehicles and assembled about 86.9GWh of power batteries. Since 2018, lithium-ion batteries will gradually enter a large-scale decommissioning period, and there are a large number of lithium-ion battery disposal problems. However, waste lithium iron phosphate lithium-ion batteries contain reusable resources, such as lithium, aluminum, copper, iron and other valuable metals and graphite and other materials. If these batteries are not handled properly, it w...

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Problems solved by technology

[0003] At present, among the methods for recovering the positive electrode materials of waste lithium iron phosphate batteries, one type is to recover lithium compounds and iron phosphate respectively by acid leaching and pH adjustment, as disclosed by the Chinese Patent Office as documents CN109095481A, CN108899601A, CN108483418A, CN108470952A, CN108461857A, etc. , in these public treatment methods, the lithium iron phosphate material is not regenerated in situ, but the lithium element and the iron element are recovered separately, the acid-base consumption is large, the recovery cost is high, and the treatment of the three wastes is difficult; another method is to directly add lithium Source, iron source or phosphorus source are calcined to prepare lithium iron phosphate materials, such as the documents CN108550940A, CN108172922A, CN107634222A, CN107275705A, CN106976852A, etc. disclosed by the Chinese Patent Office. impurity phase, the electrochemical performance of the cathode material cannot be guaranteed

Another method is the document CN106910959A disclosed by the Chinese Patent Office, which extracts lithium ions by direct oxidation methods such as persulfate, ozone, hypochlorite, etc., but does not carry out the treatment of iron and phosphorus elements or the regeneration of lithium iron phosphate. Without precise control of leaching pH, ferric phosphate solids are easily converted to ferric hydroxide

There is also the document CN109704300A, in the recovery process, the positive and negative electrode powders are peeled off from the pole piece by hydrogen peroxide, and then directly add lithium source, iron source and phosphorus source, iron is easily converted into iron hydroxide, and the crystal form of iron phosphate cannot be maintained. It is beneficial to the performance of the subsequent preparation of lithium iron phosphate, and in the subsequent recovery, citric acid is used to adjust the sol with ammonia water, which consumes a large amount of acid and alkali, the sol spray is easy to block, the process is complicated, and the acid and alkali cannot be recycled, which is easy to pollute the environment. Environmental protection is poor

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