Characterization of Aged Li-Ion Battery Components for Direct Recycling Process Design

Novel nondestructive recycling methods for lithium ion batteries (LIBs) are under investigation but lack the process engineering specifications required for full-scale operation. Specifically, the ability of end-of-life LIB components to withstand the stresses inherent in industrial manufacturing techniques has not been established. In this paper, we mechanically characterize the electrodes of both fresh and “cycle-aged” (C-A) cells, and couple this with electrochemical analysis to establish reprocessing requirements in the context of roll-to-roll (R2R) direct recycling. Cycle-aging is found to significantly reduce the tensile strength of electrodes and C-A cathodes reach elastic deformation at a lower strain than do fresh cathodes. This implies that both roll tension and calendering force may need to be reduced for C-A components relative to fresh components to avoid irreversible damage. Electrochemical analysis suggests that phase change and buildup of electrolyte residues at both the primary particle and in the inter-particle pore space may contribute to cathode degradation. The combination of these mechanical and electrochemical findings is crucial to informing the process design of industrial-scale nondestructive LIB recycling methods.