Reductive Thermal Treatment of LiCoO<sub>2</sub> from End-of-Life Lithium-Ion Batteries with Hydrogen
Haruka Pinegar, Rajashekhar Marthi, Peilin Yang, York R. Smith
Abstract
Reductive thermal treatment of lithium-ion battery (LIB) cathode material (LiCoO2) by H2 was investigated as an environmentally benign LIB recycling process. Thermogravimetric analysis of recovered LiCoO2 cathode material showed that complete reduction of LiCoO2 to Li compounds and Co by H2 took place at a lower temperature compared to that by carbothermal reduction with graphite in N2 atmosphere. Thermal reduction at 600 °C with 5% H2 demonstrated the conversion of LiCoO2 to Co and Li2O in 120 min. These compounds were successfully separated by water leaching and wet-magnetic separation. During reduction with H2 in the presence of carbon, Li2CO3 was found to form, indicating that the complete removal of carbon is necessary to produce LiOH. The activation energy for thermal reduction with hydrogen was determined by model-free kinetic analysis. In comparison with carbothermal reduction, thermal reduction using hydrogen results in a 65% decrease in activation energy.