Degradation-Informed Resource Recovery of Spent Graphite Anodes for Sustainable Lithium-Ion Battery Recycling

Abstract As lithium-ion batteries enter the terawatt-hour era, spent graphite can no longer be treated as a low-value residue within metal-centered recycling schemes. The central challenge is not simply impurity removal but the misrecognition of degradation itself. Interlayer expansion, turbostratic disorder, interfacial residues, and inherited impurities are typically regarded as damage, despite their potential to act as preactivated structural motifs. Here, we propose a degradation-informed framework for spent-graphite recycling that distinguishes features that should be removed, repaired, or directly utilized. We first analyze the multiscale failure of graphite, spanning lattice distortion, solid-electrolyte interphase (SEI) evolution, and contaminant accumulation. We then examine how separation, purification, and regeneration strategies selectively erase, preserve, or reprogram these inherited characteristics. Finally, we show that many degradation signatures, although detrimental to conventional lithium intercalation, can become advantageous in alternative electrochemical systems and other value-added applications. We argue that the future of spent-graphite recycling lies not in universal restoration to an ideal graphite state but in selective routing: structurally recoverable feedstocks should enter closed-loop regeneration, whereas defect-rich, expanded, or impurity-functionalized feedstocks are better directed to open-loop upcycling.