Recovery of lithium and cobalt from used lithium-ion cell phone batteries through a pyro-hydrometallurgical hybrid extraction process and chemical precipitation

Used lithium-ion batteries rich in valuable metals such as lithium and cobalt are usually disposed of in landfills, causing potential landfill fires and pollution of soil and waterways. A hybrid pyro-hydrometallurgical process was developed with citric acid as a leaching agent and hydrogen peroxide as a reductant to recover lithium and cobalt ions from the used cell phone batteries. Results revealed that 90.60 ± 3.43% of cobalt and 93.46 ± 4.05% of lithium were leached out, under an optimized condition of 1 M of citric acid, 3 vol% of hydrogen peroxide, 20 g L⁻¹ solid-to-liquid ratio, 80 °C leaching temperature, and 2-h leaching time. The effects of temperature, citric acid, and hydrogen peroxide concentration on leaching efficiency were investigated. Compared to similar processes in the literature, the hybrid process required relatively low reaction temperatures and organic acid concentrations. The leached cobalt and lithium ions were then converted into cobalt oxalate and lithium carbonate using oxalic acid and sodium carbonate, with recovery efficiency of 95.02 ± 3.1% and 91.5 ± 2.7% and sample purity of 99.16 ± 0.4% and 98.77 ± 0.7% achieved, respectively. This research is expected to improve the recycling of lithium-ion batteries and the like.