Application strategies of cathode materials in retired lithium battery in cascade biomass pyrolysis and reforming for hydrogen production

The convergence of agricultural waste recycling and retired lithium-ion battery (LIBs) upcycling presents a critical pathway for sustainable environmental management.This study systematically evaluates two innovative strategies, in-situ thermal reduction (ISTR) and acid-leaching loaded catalysts (ALLC), for repurposing cathode materials nickel manganese cobalt oxide, lithium cobalt oxide and lithium iron phosphate (NCM, LCO, LFP) in cascade biomass conversion systems for hydrogen production. Through controlled pyrolysis experiments, it was demonstrated that NCM cathodes undergo carbothermal reduction at 500 °C, with derived NiO species significantly enhancing biomass pyrolysis gas cracking with hydrogen yield of 19.45 mmol/g. Comparative acid leaching analysis shows that metal recovery behaviors are significantly different. Among them, the leaching efficiency of LCO/LFP using oxalic acid is higher. The leached LCO catalyst exhibits excellent carbon-carbon bond cleavage ability, achieving a hydrogen yield of 26.2 mmol/g in the reforming process. Crucially, ISTR-NMC cathode systems facilitates biomass bond cleavage and cracking, whereas ALLC LCO and LFP exhibit enhanced catalytic reforming performance, and an optimized integration work combining ISTR-treated NMC with ALLC-LCO, achieving a record 28.5 mmol/g hydrogen production through synergistic cascade reactions.This study reveals metal speciation-dependent catalytic mechanisms and closed-loop design principles for synergistic battery recycling and biomass valorization, aiming at circular economy solutions for dual waste streams via hybrid thermal-catalytic processing.