| Abstract Scope |
Recovering valuable metals from spent lithium-ion batteries (SLIBs) is crucial for sustainability. Here, we propose the use of waste ferrous sulfate (WFS) as a green reductant and sulfating agent for regenerating cathode materials from SLIBs. We demonstrate that WFS-assisted sulfation roasting, followed by oxalic acid precipitation, effectively separates, and recovers lithium (> 99%) and cobalt (> 98%). Thermodynamic simulation indicates that, as the temperature exceeds 500°C, the gas–solid reactions, driven by the large amount of SO2 released from ferrous sulfate, accelerate the sulfation. However, when the temperature is above 800°C, the decomposition of cobalt sulfate occurs, hindering cobalt leaching. Density functional theory (DFT) modeling reveals that SO2 strongly adsorbs at cobalt sites in the layered LCO structure and functions as an electron donor, reducing Co3+ to Co2+. Our research provides a promising strategy for the cost-effective and environmentally friendly recycling of SLIBs on a commercial scale. |