Conference on Environmental Science and Technology

The increasing global demand for lithium, driven by the transition to renewable energy and electric vehicles, presents significant challenges in meeting materials supply needs. Recycling lithium from end of life (EoL) lithium-ion batteries (LIBs) offers a sustainable alternative to mining. However, current hydrometallurgical recycling methods for lithium recovery from EoL LIBs are limited by the low efficiency and purity of the recovered salts. This study investigates a multi-step process aimed at lithium recovery from LIBs’ black mass involving microwave-assisted carbothermal reduction, followed by leaching in deionized water and by direct evaporation to recover lithium salts. The effects of carbothermal reduction and of leaching temperature (25 and 60°C) were explored by assessing lithium recovery as Li2CO3. Results show that microwave-assisted carbothermal reduction enhanced lithium recovery at higher leaching temperatures (60°C) by 8.06%, increasing lithium recovery from 79.78±2.08% to 86.21±10.23%. However, its effect at 25°C was negligible, recovering 79.94±7.07% of lithium without microwave-assisted carbothermal reduction and 79.34±2.44% after microwave-assisted carbothermal reduction. Given the relatively small difference between the results, the alternative approach of avoiding microwave-assisted carbothermal reduction and performing water leaching at 25°C should be explored further. Indeed, a preliminary environmental analysis revealed that greenhouse gasses emissions associated with water leaching at 25°C amount to 12.19±2.23 kg CO2 eq per 1 kg of Li2CO3, representing a 57% reduction compared to the emissions associated with microwave-assisted carbothermal reduction and water leaching at 60°C (28.47±2.80 kg CO2 eq per 1 kg of Li2CO3). Therefore, despite the technical improvements provided by microwave-assisted carbothermal reduction and water leaching at 60°C, future research efforts should be aimed at optimizing lithium water leaching at low temperatures.