AReview: Mechanisms, Processes and Design Principlesof Recycling Spent Lithium-Ion Battery and Biomass

End-of-life lithium-ion batteries (LIBs) and biomass wastes are usually studied in separate fields. This review shows that they should also be understood as complementary reaction systems. Biomass not only acts as a cheap carbon source but also provides reductive gases, biochar, organic acids, ligands, and redox-active organics to enable LIB recycling. Spent LIB-derived materials can serve as both a valuable resource and a catalyst to leverage biomass conversion. On this basis, this Review brings together three directions that are discussed in one framework: biomass-assisted thermochemical recycling, biomass-derived leaching systems, and LIB-enabled catalytic biomass valorization. This review identifies the common principles that control these processes, including oxygen potential, phase evolution, kinetics, coupled acid–redox–coordination chemistry, and catalyst design. We further compare process configurations, product pathways, and environmental trade-offs. Future work should focus on resolving coupled reaction mechanisms, defining composition and reactor design windows, integrating process-level assessment, and enabling data-driven optimization for scalable and low-impact corecycling systems.