Mechanisms, Performance Enhancement, and Future Challenges of Activation Processes in Spent Lithium‐Ion Battery Electrode Recycling

The rapid retirement of lithium-ion batteries driven by electric vehicle growth poses substantial challenges to strategic metal supply security and environmental sustainability. Conventional pyrometallurgical and hydrometallurgical recycling routes are often limited by high energy consumption, secondary pollution, and insufficient lithium recovery. Activation strategies have emerged as mechanism-guided approaches to improve spent battery recycling by regulating electrode structure, metal valence states, interfacial electron transfer, and reaction microenvironments. However, the shared activation principles, performance boundaries, and scale-up constraints across different activation processes remain insufficiently integrated. This review systematically classifies activation strategies into thermal, electron-beam, chemical, electrochemical, mechanical, and composite categories, and elucidates their underlying thermodynamic and kinetic mechanisms. It further compares their documented impacts on recovery performance, resource consumption, environmental footprint, and practical application scenarios. Representative studies show that activation can accelerate reaction kinetics, enhance selective metal extraction, and reduce energy or reagent inputs compared with conventional processes. In particular, multi-field composite activation provides opportunities for processing heterogeneous industrial black mass through synergistic regulation of reaction pathways. By clarifying challenges associated with material heterogeneity, impurity interference, reactor-scale implementation, and environmental-economic evaluation, this review establishes mechanistic insights and design principles for developing efficient, low-carbon, and closed-loop recycling technologies for spent lithium-ion batteries.