Sustainable recycling of spent ternary cathode materials via pomelo peel-mediated anaerobic roasting and low-acid...

Addressing the growing environmental and resource challenges posed by spent lithium-ion batteries, this study develops a sustainable and efficient strategy for recycling spent ternary cathode materials (LiNi_0.5Co_0.2Mn_0.3O₂) and regenerating cathode materials, utilizing pomelo peel (PP) as a green reductant. Under the optimized roasting and leaching conditions, the leaching efficiencies reached 95.7 % for Li, 96.3 % for Mn, 99.2 % for Co, and 96.1 % for Ni. Kinetic analysis indicates that the leaching behavior follows a hybrid control. The DFT and thermodynamic calculations demonstrate that pomelo peel pyrolysis gas (NH₃, CH₄, CO and H₂) effectively reduces high-valence transition metals to low-valence states, with CO playing a dominant role. The regenerated ternary cathode materials (R-NCM) delivered excellent electrochemical performance, exhibiting a first-cycle discharge capacity of 141.9 mAh/g and a coulombic efficiency of 97.6 %. It also demonstrated remarkable cycling stability, with a capacity retention of 95.1 % after 100 cycles, underscoring its robust structural integrity. By utilizing biomass waste, this process simultaneously lowers the required reaction temperature and reduces acid consumption, thereby presenting a novel and sustainable strategy for recycling spent lithium-ion batteries.