Recovery of cathode active materials from spent Li-ion batteries through thermal pre-treatment followed by leaching

• Thermal pre-treatment was carried out using a pit furnace and microwave heating. • Pre-treatment at 400 °C improves the leaching efficiency of Ni, Co, and Cu. • Higher temperatures lower Ni recovery due to residue formation. • LiF formation in residues indicates incomplete Li extraction. • Controlled heating enables selective Li–Mn recovery (Mn yield = 96.8 wt%). As the markets for electric vehicles and portable electronics continue to grow, global demand for cathode active materials is increasing significantly. This study investigates the effect of thermal pre-treatment on the black mass from spent Lithium-ion batteries (LIBs) and its impact on the leaching efficiency of cathode active materials. Thermal pre-treatment of black mass samples was carried out using a pit furnace and microwave heating at temperatures ranging from 400 °C to 1200 °C. The thermally treated samples were then leached using both water-based and acid-based solutions to extract the valuable metals. The results indicate that thermal pre-treatment of black mass using both microwave and conventional heating methods improves the leaching of Ni, Co, and copper (Cu). At pre-treatment temperatures exceeding 600 °C, Ni retention in the residues increases for both sulfuric acid and carbonated water leaching processes. X-ray diffraction (XRD) analysis of the leaching residues also revealed the presence of LiF, suggesting that incomplete Li extraction resulted from the formation of insoluble compounds. Thermal pre-treatment in a pit furnace at temperatures above 800 °C promoted selective recovery of Li and Mn, yielding 96.8% Mn at 800 °C. These findings indicate that thermal pre-treatment has a significant impact on the selective recovery of cathode active materials from spent LiBs, therefore, careful optimisation of thermal conditions can enhance the targeted extraction of valuable metals and promote the sustainability of recycling processes for spent LiBs.