Recovery and regeneration of lithium cobalt oxide from spent lithium-ion batteries through a low-temperature ammonium sulfate roasting approach

The operating temperature determines the energy consumption and lithium extraction rate of a pyrometallurgical process. This paper aims to employ a molten ammonium sulfate ((NH4)2SO4) assisted roasting approach to recovering and regenerating LiCoO2 from spent lithium-ion batteries (LIBs) at 400 °C. First, cathode materials from the spent LIBs are converted to CoSO4 and Li2SO4 via a sulfation roasting approach. Both recovery rates of Li and Co reach over 98% at 400 °C for 2h and at an (NH4)2SO4/(cathode materials) mass ratio of 4:1 in Ar atmosphere. Then, the obtained Co(OH)2 and Li2CO3 are used to regenerate LiCoO2 that delivers a specific capacity of over 154 mAh g−1 at 1C with capacity retention of 94% after 100 cycles. Overall, the molten (NH4)2SO4 assisted roasting approach reduces the operating temperature to 400 °C while maintaining a high extraction rate of over 98% for both Li and Co, promising an energy-efficient approach to recovering various cathode materials from spent LIBs.