A comprehensive review: Evaluating emerging green leaching technologies for recycling spent lithium-ion batteries

The market demand for lithium-ion batteries (LIBs), driven by energy storage devices such as electric vehicles, has surged, intensifying environmental concerns over spent LIB accumulation and the depletion of nonrenewable metal resources. This demand spurs technological advancements. However, traditional pyrometallurgical and acid-based hydrometallurgical methods have significant environmental drawbacks, underscoring the need for viable, green innovations in LIB recycling to ensure sustainable industry growth. Compared with pyrometallurgy, hydrometallurgy offers greater sustainability benefits. In this review, we introduce the concept of "Biomass-derived Reagents" applied to LIB recycling and systematically examine the latest feasible green leaching technologies, including deep eutectic solvent leaching, bioleaching, the development of biomassderived reagents, and the application of supercritical fluids. Each technology is critically evaluated and its future potential is discussed. This work aims to offer a practical and effective reference for sustainable technological advancements in the LIB recycling sector, contributing valuable insights for both industry development and environmental protection.