Selective lithium recovery from spent NCM cathodes via starch-assisted roasting

Efficient and selective separation of lithium from spent lithium-ion batteries is paramount for sustainable battery recycling. In this study, the lithium extraction selectivity over spent ternary cathode materials (SNCM) was successfully tuned for preferential lithium recovery by employing starch as a green reductant under a controlled air atmosphere. Under optimized conditions (roasting temperature: 700 °C, SNCM-starch mass ratio: 1:2, air flow rate: 20 mL/min, roasting time: 30 min, liquid-solid ratio: 50 mL/g, water leaching time: 30 min), lithium was preferentially leached with a high efficiency of 97.50%, while the transition metals remained in the solid residue. Systematic characterization and mechanistic investigations revealed that the layered framework structure of SNCM collapsed during starch-assisted roasting, ultimately leading to the formation of low-valence Ni, Co, MnO, and water-soluble Li₂CO₃. Notably, the introduction of a controlled air atmosphere inhibited the encapsulation of lithium carbonate by biochar, thereby significantly enhancing Li leaching efficiency. Overall, this work offers a promising way to develop efficient, green, and economical recycling processes for spent lithium-ion batteries with controllable metal selectivity.