Pomegranate peel as an Ecofriendly Reductant for Efficient Recovery of Cathode Materials from Spent Lithium ion Batteries through Organic Acid Leaching

Nowadays, the recycling of valuable metals from spent lithium-ion batteries (LIB) using hydrometallurgical processes is on the rise. Therefore, using safer leaching media for the dissolution and environmentally friendly chemicals are essential. In this research, a feasibility study of the recovery of valuable metals, including lithium, cobalt, manganese, and nickel, from the cathode of spent LIB in acidic conditions using pomegranate peel (PP) as a green reductant was evaluated. To optimize the dissolution process, the effects of various parameters, such as CH ₃ COOH concentration, temperature, time, and the PP/LIB, were investigated using response surface methodology (RSM) experimental design. Based on ANOVA, linear models were obtained for Co, Mn, and Li recovery, except for the Ni recovery model. According to the results, temperature was identified as the most crucial factor in the recovery of Ni, Co, Mn, and Li, due to the facile hydrolysis of PP at elevated temperatures. Based on the optimization results for leaching cathodes of LIB in the presence of PP, the predicted recovery values for Ni, Co, Mn, and Li at the optimum point of 320 min, 5.5 M CH ₃ COOH concentration, 92°C temperature, and PP/LIB of 3.5 g/g were 83.3, 85.9, 84.9, and 91.2%, respectively, which showed good agreement with the calculated results from the experimental recovery. FTIR characterization of leaching samples in the presence and absence of PP indicated that glucose molecules produced during dissolution were immediately consumed by LIB compounds. Furthermore, the leaching kinetics study of LIB cathodes in the presence of PP demonstrated that the dissolution mechanisms of Ni, Co, Mn, and Li followed the Avrami model.