Recycling of spent lithium-ion batteries via sulfidation shock

Extracting battery metals from spent lithium-ion batteries (LIBs) is a promising solution to address the crisis in battery material supply and the risk of heavy metal pollution. This study proposes a selective sulfidation shock (SS) strategy for the recovery of battery metals from LIBs. The transient high temperatures (similar to 1000 degrees C) generated by pulsed direct current induce solid-phase interfacial sulfidation reactions of lithium (Li) in cathode particles, preventing the generation of sulfur-containing flue gases while enhancing the selective recovery of Li metal. The thermal shock causes Li to quickly volatilize and concentrate on the cathode particle surface owing to saturation vapor pressure differences between Li and transition metals, where it reacts with the high-melting-point sulfurizing agent (CaSO4) to produce easily soluble Li2SO4. The SS process rapidly achieves the transformation of lithium-containing phases within mere seconds, and the subsequent leaching rate of Li in water increases from 40 % to 89 %, with the leaching kinetics improved by 36 times. In addition, thermal shock also promotes the release of lattice oxygen, thereby synergistically enhancing the reduction leaching of transition metal oxides. A comprehensive life cycle assessment revealed that this SS strategy can reduce greenhouse gas emissions by 22 %-43 % compared to traditional pyrometallurgical and hydrometallurgical processes while also yielding 4.97 USD/kg economic benefits.