Comparative Study of Hydrogen and Carbothermal Reduction for Recycling of Spent Lithium-Ion Batteries

Recovery of critical metals such as Li and Co from the spent lithium-ion batteries is necessary to alleviate resource scarcity and mitigate supply risk. The present study emphasizes the carbothermal and hydrogen reduction of lithium cobalt oxide (LCO) and the recovery of Li and Co from spent LCO-based batteries. Carbothermal reduction (CR) and hydrogen reduction (HR) at 500–900 °C followed by water leaching was carried out for Li recovery. Complete reduction with hydrogen was achieved at 500 °C, whereas a significant reduction for CR was achieved at 700 ℃. Characterization analysis of the reduced products affirms the decomposition of the layered LCO structure with the evolution of new phases. CR favored the Li 2 CO 3 formation, while the LiOH phase was observed in the HR products. Both reductive treatments yielded metallic Co, but CoO was also found in the CR products. The hydrogen reduction was found better compared to carbothermal reduction for both Li and Co recovery. CR process at 900 °C resulted in 61% Li dissolution and 76.5% Co recovery, while HR at 500 °C yielded much higher Li dissolution (93%) and Co recovery (86.5%).