Conversion of cobalt from spent LIBs to Co3O4 electrode material for application in supercapacitors.

The cathode material of lithium-ion batteries (LIBs) is endowed with valuable metals, such as cobalt. The improper treatment of these batteries pollutes the environment and causes enormous resource waste. Therefore, the recovery of valuable metals from spent LIBs has attracted widespread attention. In this study, Co₃O₄ electrode materials were prepared by a simple homogeneous precipitation method and heat treatment using a leaching solution of spent LIBs-positive electrode material as the cobalt source. The crystal structure and morphology of the products were examined at different annealing temperatures, and their electrochemical performance was analyzed. The results show that low-temperature annealing contributes to grain refinement. The Co₃O₄ material prepared at 300°C annealing temperature has a rod-like structure with distinct pores and a specific surface area of 58.98 m2 g^-1. Furthermore, electrochemical performance testing reveals that Co₃O₄ prepared at 300°C displays the best electrochemical performance as an electrode material, with a specific capacitance of 97.93 F g^-1 and a cycle retention rate of 79.12% after 500 charge-discharge cycles. These findings demonstrate the feasibility of recycling valuable metal cobalt from spent LIBs cathode materials to produce Co₃O₄ materials for use as supercapacitor electrode materials, opening up new avenues for the recycling and utilisation of spent LIBs.