Enhanced efficiency of electrowinning for cobalt recovery from spent lithium-ion battery

This paper presents a comprehensive study of improving cobalt recovery from spent lithium-ion batteries via electrowinning. A constant-current power supply with closed-loop control (CCPS) is developed and applied as the power source for electrowinning. The optimal operating conditions are then determined using the synthetic electrolyte and subsequently applied to a real leachate obtained from spent Li-NMC batteries. The CCPS can operate effectively in constant-current mode from 50 to 200 A/m2 with over 98% accuracy. The optimal conditions are an initial cobalt concentration of 5,000 ppm, a current density of 110 A/m2, a temperature of 45 °C, an electrowinning time of 100 min, and a pH of 4. For the synthetic electrolyte, the maximum current efficiency and cobalt recovery exceed 90% and 96%, respectively. In the real leachate application, the maximum current efficiency remains high at 99.21% and the cobalt recovery is at 60% due to co-deposition with other metals.