Method for recycling positive-negative electrode mixed material of waste ternary lithium-ion battery

Abstract

The invention provides a method for recovering a positive-negative electrode mixed material of a waste ternary lithium-ion battery. The method comprises the following steps: discharging and disassembling the waste lithium-ion battery to obtain nickel-cobalt lithium manganate positive electrode and silicon-carbon negative electrode mixed powder, a battery shell, a copper foil, an aluminum foil anda diaphragm; performing mixing, ball-milling and roasting on the mixed powder and carbonate and recycling CO2 generated in the reaction process; putting a roasted mixture into a dilute alkali solution, filtering, introducing CO2 to separate silicon and aluminum in a filtrate, dissolving filter residue in an acid, leaching Li<+>, Ni <2+>, Co <2+>, Mn<2+> and Cu <2+> in the filter residue, filteringto remove graphite, and recovering negative electrode material carbon by a solid phase method; adding sulfide into the leachate, adjusting the pH value to remove impurity copper, and preparing a nickel-cobalt-manganese hydroxide ternary precursor through a coprecipitation method; introducing CO2 into the filtrate, heating, concentrating and crystallizing to prepare lithium carbonate. The method is simple in process, low in cost, high in recovery rate and capable of achieving the full-component recovery of the nickel cobalt lithium manganate positive electrode and a silicon carbon negative electrode mixed material, and 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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