Extraction of critical raw materials from spent lithium-ion battery black mass by leaching process

Global interest in efficient recycling methods is growing due to the increasing reliance on lithium-ion batteries and the scarcity of critical raw materials. Despite their importance, current battery recycling technologies remain underdeveloped. Recycling is essential not only for environmental and economic sustainability, but also for reducing the EU's dependence on critical and strategic materials. This study aimed to identify the optimal conditions for maximizing the leaching efficiencies of six critical raw materials (CRMs) from black mass using a Taguchi-based grey relational analysis. Based on the experimental results from a series of leaching experiments designed using the Taguchi L25 orthogonal array, the optimal conditions were identified as using hydrochloric acid (HCl) at a concentration of 1.7 M, adding 3 vol% H₂O₂ as a reducing agent, at a leaching temperature of 75°C, a reaction time of 150 min, and a liquid-to-solid ratio of 50 mL/g. Under the identified optimum conditions, the average leaching efficiencies achieved for cobalt, manganese, aluminium, lithium, nickel, and copper were 97.60%, 96.16%, 96.72%, 99.96%, 95.84%, and 99.98%, respectively.