Towards preferential lithium recovery from spent lithium-ion batteries: phase transition mechanisms, technical innovation and future perspectives

Lithium is an indispensable element for the sustainable development of the new energy industry. However, the strong market demand for LIBs has led to a shortage of lithium resources. Recycling lithium from spent LIBs is an effective approach to alleviate the lithium shortage. However, LIBs are all artificially synthesized complex materials, and phase transition is an indispensable pathway to extract lithium selectively and efficiently. The phase transition methods can be divided into two types: lithium selective leaching in the liquid phase and lithium preferential extraction in the solid phase. This review systematically summarizes the available methods for selective lithium recovery and analyzes the phase transition mechanism from a thermodynamic perspective. The environmental impact and economic benefits analysis were presented for selective lithium extraction methods in liquid phase systems. Innovatively, the “reactivity-selectivity principle” was first employed to evaluate the main solid phase transition methods, indicating the importance of phase transition control for higher lithium recovery efficiency and selectivity. Finally, the prospects of lithium recycling development were outlined from four dimensions of technological innovation, entire-process optimization, economical efficiency and environmental friendliness. This review aims to provide references and enlightenment for the efficient recycling of spent LIBs from the perspective of phase transition and assist in the healthy and long-term development of new energy industry.