A grave-to-cradle analysis of lithium-ion battery cathode materials using material and energy circularity indicators

The future demands for lithium-ion batteries required for powering the electrification transition in transportation and energy storage will lead to vast amounts of waste, demanding proper end-of-life strategies. As various recycling routes are continuously developed to address this issue, a significant challenge is the fair comparison of processes entailing different unit operations and transformation stages. Indeed, the choice of metallurgical or direct recycling routes results in diverse materials flows and energy demands. To allow a suitable comparison between technologies, this work presents a grave-to-cradle analysis of cathode materials (i.e., lithium cobalt oxide) considering three recycling processes representative of the most popular routes (i.e., pyrometallurgical, hydrometallurgical, and direct recycling). Unlike previously published works, a system-level analysis of both material recovery and energy preservation was carried out using statistical entropy and exergy analysis, respectively. Furthermore, comparison of processes using exentropy, a recently proposed circularity parameter combining both material recovery and energy preservation, was performed for the first time. The results highlight the need of a robust multidimensional analysis of processes to properly determine their suitability according to the needs of the circular economy. When materials and energy preservation were analyzed independently, two different routes were identified as optimal. The need of a robust multidimensional analysis of processes to properly account for the goals of the circular economy is thus highlighted. Exentropy analysis suggested that direct recycling provides the optimum alternative in terms of energy utilization for the recovery of materials.