Recovery of cobalt from spent lithium-ion battery cathode materials by using choline chloride-based deep eutectic solvent

Abstract

Recycling of spent lithium (Li)-ion batteries has become a hot research topic due to its surge in the quantity and environmental problems. Herein we demonstrated a new chemical configuration of choline chloride-based deep eutectic solvent (DES) to recover the cobalt from lithium cobalt oxide (LiCoO2), a representative cathode material for Li-ion battery. It was experimentally verified that the leaching efficiency of Co increased rapidly with the increase in the reaction temperature. Nearly 96% of Co can be leached from lithium cobalt oxide after a leaching treatment at 200° for 20 h. The leaching mechanism of cobalt in DES was analyzed by using a variety of techniques, including cyclic voltammetric experiments, Fourier transform infrared radiation, and ultraviolet-visible spectra. The results showed that the LiCoO2 dissolve into the DES via reduction of Co(iii) to Co(ii). In particular to this work, the leaching experiments were performed in a higher concentration than those in the previous studies, which significantly promoted the operating efficiency of the leaching process.