Recycling method of positive and negative mixed materials of waste ternary lithium ion battery

Abstract

The invention provides a method for recycling the positive and negative mixed materials of waste ternary lithium-ion batteries, comprising the steps of: disassembling the waste lithium-ion batteries after discharge to obtain mixed powder of nickel-cobalt lithium manganese oxide positive electrode and silicon-carbon negative electrode, battery casing, Copper foil, aluminum foil and diaphragm; the mixed powder and carbonate are ball-milled and then roasted to recover the CO generated during the reaction 2 ; Put the calcined mixture into the dilute alkali solution and filter it, then pass it into CO 2 , the silicon and aluminum in the filtrate are separated, the filter residue is dissolved in acid, and the Li in the filter residue is leached + 、Ni 2+ 、Co 2+ , Mn 2+ and Cu 2+ , after filtering to remove graphite, recover negative electrode material carbon by solid phase method; add sulfide to the leaching solution, adjust the pH value to remove impurity copper, and then prepare nickel-cobalt-manganese hydroxide ternary precursor by co-precipitation method; CO 2 Pass into the filtrate, heat up, concentrate and crystallize to prepare lithium carbonate. The invention has a simple process, can realize the recovery of all components of the nickel-cobalt lithium manganese oxide positive electrode and the silicon-carbon negative electrode mixed material, has low cost, high recovery rate, and the resources can be recycled.

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 recycling positive and negative mixed materials of waste ternary lithium-ion batteries with silicon-carbon negative electrodes. Background technique [0002] Since 2014, my country's new energy vehicles have developed rapidly, and production and sales have shown a high-speed growth trend. According to data from the China Association of Automobile Manufacturers, the sales volume of new energy vehicles in 2018 has reached 1.256 million, which is 16.8 times the sales volume in 2014. It is estimated that the sales volume may reach 2.3 million by 2020. The general scrapping period of lithium iron phosphate batteries is 5 years, and the scrapping period of ternary lithium batteries is 6 years. It is expected that power batteries will enter a large-scale scrapping period at the end of 2019. By 2020, the installed capacity of scrappe...

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Problems solved by technology

[0005] 1) The cost of recycling silicon carbon negative electrode materials is high; 2) The scope of applicability of conventional methods is narrow, and only a single positive or negative active material can be recovered, and the recovery of a single positive or negative active material makes the front-end dismantling and crushing process complicated; 3) Leaching is commonly used The reductants in the system include liquid hydrogen peroxide, solid sodium sulfite and gaseous hydrogen sulfide. However, the addition of these reductants may introduce new impurity elements on the one hand, increase recovery routes, and increase the storage and management costs of the reductant on the other hand;4 ) impurity removal methods are commonly used extraction, neutralization reaction, the extraction process equipment investment is relatively large, the cost is high, and a large amount of sewage is generated, and the colloidal precipitate generated by the neutralization reaction is difficult to filter

5) It is difficult to achieve recycling by adding raw materials in the traditional recycling process

[0006] The Chinese Patent Office has disclosed some waste ternary lithium-ion battery recycling processes. In these published documents, some processes can only be recovered for a single positive electrode material, and can only be completed after multiple precipitations; When using iron powder to reduce copper, then use the iron ore method to filter iron, and then add alkaline solution to remove aluminum. The more times this method precipitates in the solution, the more serious the loss of valuable metals will be, because Ni ions It will be precipitated at a pH of about 3. Therefore, this method has more entrainment and is prone to produce impurities. It is difficult to guarantee the product phase and electrochemical performance of the recovered material. In addition, acid-base dissolution and extraction are continuously used in the process, and acid-base consumption It is relatively large, and it will produce a large amount of waste water at the same time, and it is difficult to treat the three wastes; there is also a process that disassembles the waste lithium battery and then burns it with sulfate. In the liquid extraction, due to the relatively high pH of aluminum removal, a large amount of nickel and cobalt elements will be lost and the recovery rate will be reduced.

[0007] However, in the recycling methods of waste lithium-ion batteries involved in the above-mentioned published patent documents, they are all innovations aimed at making the negative electrode material graphite, and do not involve the recovery of silicon carbon as the negative electrode material.

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