Low-Carbon Circular Recycling of Spent Lithium-Ion Battery Cathodes via Direct Regeneration and High-Value Upcycling

Abstract

With the rapid expansion of electric vehicles and grid-scale energy storage industries, the first generation of lithium-ion power batteries worldwide is approaching large-scale retirement, leading to a surging volume of spent lithium-ion batteries (S-LIBs). Pyrometallurgical and hydrometallurgical recycling are constrained by high energy consumption, substantial carbon emissions, and heavy wastewater treatment burdens. In contrast, direct cathode regeneration and upcycling technologies restore or reconstruct the microstructure to recover performance or enable functional upgrading, offering a short-process recycling pathway toward low-carbon circular utilization. This work systematically reviews the routes of solid-state thermochemical, liquid-phase chemical, and electrochemical regeneration. Building on this framework, we elucidate how lithium replenishment, defect repair and phase reconstruction collectively govern the restoration of electrochemical performance. Beyond regeneration, we highlight research progress on environmental functional materials and energy materials derived from spent cathodes, including pollutant degradation, CO2 capture, energy conversion and storage, with particular emphasis on roles of phase-transition regulation, defect engineering, and interface engineering. Finally, we benchmark the technological, economic, and environmental impacts of cathode regeneration and high-value upcycling, revealing the fundamental obstacles to the large-scale adoption of these approaches.