Highly efficient recovery of Lithium and Cobalt from lithium batteries using Deep Eutectic Solvents and low temperature pyrolysis

It is estimated that 30% of the vehicle market will comprise full battery, hybrid and plug-in hybrid electric vehicles by 2030[1]. In order to keep up with the overarching demand of modern electronic and electrification of transportation, battery industries must start to apply a circular economy vision based on the recovery of raw materials (Co, Li, etc.) from exhausted batteries, using innovative and eco-sustainable approaches. DES are an emerging class of green solvents based on binary or ternary mixtures with huge melting point depression at the eutectic composition compared to those of the components.[2] They are formed by mixing hydrogen bond donors (HBD ;e.g., urea, glycerol, carboxylic acids, acetamide, etc.)and hydrogen bond acceptors (HBA; typically choline chloride (ChCl) or other quaternary ammonium chlorides) [3]. In this work a selective extraction and highly efficient recovery method was developed and optimized using economic and low-impact Deep Eutectic Solvents (DESs) composed by three reagents: Choline Chloride (ChCl), Ethylene Glycol (EG) and Citric Acid (AcC). The LiCoO2 (LCO), recovered from exhausted secondary batteries was leached at 140°C for 30 min with a rate LCO:DES 25 g/L in order to obtain a full extraction of lithium and cobalt. The resulting solution was subsequently treated at 500°C for 4h, obtaining Co3O4 and LiCl. Finally, the two powders were treated at 800°C for 2h with a molar ratio Li:Co 1.10:1 to regain the starting cathode, which was subsequently used to prepare a second-life cell and compared with a commercial one.