Improved recovery of cathode materials and enhanced lithium selective extraction from spent LiNi0.5Co0.2Mn0.3O2 batteries via CaCl2-assisted microwave roasting

Abstract

Effective separation of cathode materials (CMs) from Al foils is critical for recycling spent lithium-ion batteries (LIBs). This study proposed a CaCl2-assisted microwave roasting technology for facile exfoliation of cathode materials and selective recovery of lithium. The specific action mechanism was studied by experiments and thermodynamic calculations. Under the action of microwave, CaCl2 accelerated decomposition into chlorine-containing gas and rapidly diffused in cracks caused by thermal stress to ensure the separation of Al foil and active material layer. The decomposition product of CaCl2 acts as an adsorbent to capture HF released by polyvinylidene difluoride (PVDF), inhibiting the fluorination reaction with electrode materials. The water vapor generated from the CaCl2 and CMs promotes the diffusion of Li+ out of the crystal lattice and then reacts with H2O and HCl to form water-soluble LiCl. Finally, 93.4 wt% CMs can be detached from Al foils, and 91.5% Li in the cathode powders could be extracted by subsequent water-leaching under optimal experimental conditions. These results show that this technology can provide both economic and environmental benefits, and have important guiding for the development of green and sustainable ways to efficiently recycle spent LIBs.