Leaching Optimization of Battery Black Mass for Lithium Recovery by Electrochemical Junction Transfer (ETJ) Technology

A process of cation recovery based on intercalation properties into host matrix has been previously developed in the laboratory. It consists in a selective extraction from a waste electrolyte (battery leachates, industrial effluents...) to a recovery electrolyte, separated by an Electrochemical Junction Transfer (ETJ). The ETJ is constituted of a porous material coated by an active matrix (LiMn2O4). The transfer from synthetic electrolytes like Li2SO4 was successfully carried out whereas the transfer from real waste (spent Li-ion batteries leachate) was problematic. First studies by cyclic voltammetry confirmed a limited behaviour and showed that the blockage could be attributed to 2 phenomena: the presence of organic compounds coming from Li-ion battery components and the acidity of leachates during transfer. The goals of our work were to eliminate these organic compounds and to define the optimized pH range for an efficient transfer. Different methods (chemical treatment on leachates or thermal treatment directly on crushed battery Black Mass) for removing organic compounds were performed. After a thermal treatment on Black Mass (T = 500 degrees C, t =72 h) and a pH adjustment (pH = 5), the selective transfer of Lithium was carried out with a faradic yield close to 100%.