Electrolytic separation and reuse of cathode materials from discarded lithium-ion batteries

Abstract

The end of the service life of electric vehicles, and it is expected that a large number of electric vehicles will enter the phase of scrapping and recycling in the next few years. The precious metals in batteries, if not disposed of properly, pose a threat to the environment and public health. In this study, the roll plating tank used for electroplating was used as a reaction device for the first time. It is adaptable and generates friction to improve electrolysis efficiency. At the same time, a method is proposed to separate cathode materials and aluminum foil under low-voltage conditions, allowing for the preferential recovery of 99 % of Li and resynthesize high nickel cathode materials. The cathode material and aluminum foils were completely peeled off without disaggregation. The effects of electrolysis voltage, electrolyte species, electrolyte concentration, and electrolysis temperature on separating cathode material, aluminum foil, and lithium dissolution were investigated. Under the optimum conditions, the efficiency for dissolution of Mn, Co, and Ni in the electrolyte is not more than 1 %. In comparison, the efficiency for dissolution of Li is more than 99 %, achieving the selective separation of valuable metals. Na₂CO₃ was added to the filtered electrolyte to generate Li₂CO₃, which was then purified to obtain battery-grade Li₂CO₃. The filter residue was acid-leached, and the co-precipitation method synthesized the filtrate after acid-leaching. The ternary precursor was synthesized by solid-phase synthesis with the precursor and battery-grade Li₂CO₃ to prepare a LiNi_0.5Co_0.2Mn_0.3O₂ material with excellent electrochemical performance. The purpose of this study is to provide theoretical and technical support for the electrochemical recovery of ternary cathode materials.