Efficient sulfuric acid-Vitamin C leaching system: Towards enhanced extraction of cobalt from spent lithium-ion batteries

Cobalt (Co), a rare and valuable metal, is used extensively to prepare lithium cobalt oxide (LiCoO 2 ) employed in lithium-ion batteries (LIBs). Developing an effective method to recover Co from spent LIBs is of great economic significance. In the present study, we designed an efficient sulfuric acid-vitamin C system for the extraction of Co from spent LIBs and determined the effects of operational parameters on the extraction of Co. The results showed that there were optimum values for the concentration of sulfuric acid and leaching temperature in promoting leaching. For vitamin C, its effectiveness increased with concentration to a maximal value, but raising the concentration further was without significant effect. The leaching time hardly affected the extraction of Co. Although changes in solid–liquid ratios at low value did not greatly influence recovery, high ratios significantly decreased it. The final optimized experimental scheme was derived from a simulation using the Design-Expert 8.0.6.1 software. Optimal reaction conditions, under which 95.5% of Co was recovered, contained 3 mol·L −1 sulfuric acid and 0.56 mol·L −1 vitamin C with S / L ratio at 15 g·L −1 and leaching temperature of 70 °C. The present work describes a potentially promising technology for the recovery of cobalt from spent LIBs.