Priority Lithium recovery from spent Li-ion batteries via carbothermal reduction with water leaching

Abstract

Lithium is one of the most valuable elements within lithium-ion batteries, but it is also one of the least recycled metals owing to its high reactivity, solubility, and low abundance. This work presents an improved carbothermal reduction combined with a water leaching process for lithium recovery from Li(NixMnyCo1-x-y)O2 cathode materials. Based on the thermodynamic analysis of the carbothermal reduction, the reduction products at different temperatures are clarified. The effects of various factors such as roasting temperature, liquid-solid ratio, and leaching time are assessed on lithium leaching efficiency. The reduced products are characterized by XRD, SEM-EDS, and SIMS. Results show that Co and Ni are reduced to metal, Mn remains as an oxide, whilst Li is converted mainly into Li2CO3 at temperatures lower than 800 ℃ and Li2O when the temperature exceeds 900 ℃. Water leaching was used to efficiently extract lithium using low liquid-solid ratios. This improved lithium extraction process can effectively recover more than 93% of lithium as lithium hydroxide or carbonate at a purity greater than 99.5%. The effect of aluminium and copper impurities on the lithium recovery rate was investigated and it was found that copper has no significant effect on the lithium recovery rate, but the presence of aluminium decreases the lithium recovery rate through the production of lithium aluminate.