Comparative environmental and economic assessment of emerging hydrometallurgical recycling technologies for Li-ion battery cathodes

Abstract

The growing demand for electric vehicles has led to a growing concern for battery recycling, particularly for critical raw materials. However, there is insufficient investigation into the environmental and economic impacts of hydrometallurgical recycling methods. In this study we explored emerging hydrometallurgical technologies in economic and environmental perspective to establish conceptual routes to recover Co, Ni and Mn oxides from waste LiNi_0.33Mn_0.33Co_0.33O₂ cathode materials from spent Li-ion batteries. After, life cycle assessment and costing techniques were utilized to compare the environmental and economical performances of each conceptual route. Recovery efficiency of metal oxides through each route was also considered as a key factor. Results suggested that deep eutectic solvent-based leaching produces the highest impact under many impact categories while electrolysis-based leaching showed the least. Under purification technologies assessed, ion-exchange based purification showed significantly lower impact under many categories except stratospheric ozone depletion. Solvent based purification has been identified as the worst technology for purification. Hydroxide based calcination has been identified as the most environmentally sustainable calcination method compared to oxalate calcination. The route consists with inorganic leaching, ion-exchange based purification and hydroxide calcination showed the lowest environmental impact (emission effect at 33.8 kg CO₂ eq), with lower economic impact ($ 119) and the highest recovery efficiency (78 %) per 1 kg of cathode active materials. However, using electrolysis-based leaching can slightly increase the impacts with lower recovery efficiency (75 %) and better economic performance ($104/kg of cathode active materials). Terrestrial ecotoxicity was identified to be the most affected impact category for the recovery processes. It is recommended that technologies like deep eutectic solvent-based leaching, solvent extraction and environmentally sustainable technologies like supercritical fluid extraction need further studies prior to industrial applications.