Effect of In-Situ Catalyst on Co Extraction from Lithium-Ion Battery Scrap Via Selective Sulfation Roasting

Recycling of lithium-ion batteries has become essential to meet the demand for critical raw materials, especially lithium (Li) and cobalt (Co). Selective sulfation roasting followed by water leaching has been shown to be a promising route for recycling. However, it is very challenging to achieve high metal recovery efficiencies consistently with different batches of battery scrap because of their complex morphology and continuously changing chemistries. In this study, two different batches of lithium cobalt oxide (LCO)-rich black mass were treated by selective sulfation roasting and a water leaching process under similar conditions. The metal recovery efficiency of Li was observed to be consistently very high, whereas Co extraction efficiency was found to vary dramatically from one batch of black mass to another. It was demonstrated that this variation in metal extraction efficiency was mainly due to the considerably higher iron concentration in the first batch of black mass, where iron oxide acted as a catalytic agent and enhanced the formation kinetics of cobalt sulfate, resulting in higher Co recovery during water leaching. The catalytic effect of Fe₂O₃ was confirmed by demonstrating the enhancing effect on metal extraction efficiency by sulfation roasting with addition of Fe₂O₃ in LiCoO₂ powder and low-iron black mass.