Cathode active material recycling from spent lithium batteries: a green (circular) approach based on deep eutectic solvents.

The transition to a circular economy vision must handle the increasing request of metals required to satisfy the battery industry; this can be obtained by recycling and feeding back secondary raw materials recovered through proper waste management. Here a novel and green proof-of-concept is proposed, based on deep eutectic solvents (DES) to fully and easily recover valuable metals from various cathode active materials, including LiMn 2 O 4 LiNi 0.5 Mn 1.5 O 4 and LiNi 0.8 Co 0.2 O 2 . DES composed of choline chloride and lactic acid can leach Li, Mn, Co and Ni, achieving efficiency of 100% under much milder conditions with respect to the previous literature. For the first time, to our best knowledge, a two-step approach is reported in the case of LiNi 0.8 Co 0.2 O 2 for selective recovery of Li, Co and Ni with high yield and purity. Furthermore, other cathode components, namely aluminium current collector and binder, were found to be not dissolved by the proposed DES, so making it possible for a simple separation from the active material. Finally, our strategy is designed to easily regenerate and reuse the leaching solvents for more than one extraction, thus further boosting the process's sustainability.