Water leaching after sulfur roasting: An advanced approach for prior extraction of lithium from lithium-ion batteries (LIBs)

The economical and environmentally friendly technique for recycling valuable metals from LIBs plays a vital role in the sustainable development of the LIB industry. Simplifying the overall technological process of recycling LIBs cathode materials relies heavily on the prior extraction technique of Li from LIBs. In this study, we propose a novel process combining sulfur roasting treatment and water-leaching process after roasting treatment to selectively and efficiently recycle Li from LIBs cathode materials. At First, thermodynamic analysis demonstrates the feasibility of the reactions between LIBs cathode materials and sulfur. The application of sulfur as an economical reductant allows for the conversion of Li to soluble Li₂SO₄, which can therefore achieve the preferential extraction of Li. The formation reactions of NiSO₄ and CoSO₄ do not occur, and the strong binding affinities between Ni, Co, and S lead to the formation of Ni₃S₂ and Co₉S₈ during the roasting process. Under the following conditions of the roasting temperature of 550 °C, the time of 120 min, and the S/Li (mole ratio) of 1.3, the Li leaching ratio of NCM can reach 80.50 %. The feasibility of this technique is confirmed by the production of Li₂SO₄ obtained from the leachate through evaporation and crystallization. This research presents an alternative economical process for preferentially recycling Li from spent LIBs.