Toward energy-efficient recycling of spent LiFePO4 cathode: Lowering reduction temperature though bamboo-assisted pyrolysis and sodium carbonate-mediated in-situ mineralization

While the imperative for a low-carbon energy transition and electrification substitution has established electric vehicles (EVs) development as a critical strategy for carbon emission reduction, power battery recycling consequently represents a pivotal link in completing the lifecycle management of EVs. Herein, we report a novel approach for recovering lithium iron phosphate (e.g., LFP) from spent batteries based on a synergistic pyrolysis process. Biomass and sodium carbonate are used together to disrupt the olivine structure through carbothermal reduction with a relatively low temperature. The results indicated that biomass generated more reducing gases and phenolic compounds through sodium carbonate-assisted pyrolysis, which lowered the reduction barrier for the metal oxides in spent LFP, substantially reducing the reaction temperature by 240 °C compared to conventional graphite reduction. Moreover, sodium carbonate effectively suppresses the volatilization of lithium at high temperatures, enabling high recovery efficiencies of 93% from iron and 95% from lithium. The scalability was confirmed by bench-scale experiments, which showed consistent recovery performance at a 50-fold scale increase. The environmental benefits of this pathway, as per life cycle assessment, reduce the environmental footprint and align with industrial green standards. This study presents a novel recycling strategy for spent LFP, based on a biomass-assisted reduction process with a mineralization agent. The incorporation of biomass addresses both economic and environmental challenges, thereby establishing a cost-effective and green technology suitable for the large-scale recycling of LFP.