Extraction of metals from spent lithium ion batteries: role of acid, reductant and process intensification in recycling

This paper presents a comparison of various approaches evaluated to process spent lithium ion batteries to extract metals. The leaching was carried out with sulphuric acid in presence and absence of reductant, thus defining the role of reducing agent (NaHSO3 and H2O2) in assisting dissolution of all metals, especially Co and Mn. As the direct process incurs all metals in solution and employs high concentration of acid, a two-step process (acid baking and leaching) was attempted to lower acid consumption indicating benefits in the selective dissolution of metals viz., Co and Li (in 1st stage) over other metals (Ni and Mn in 2nd stage).