A Proof-of-Concept Study on Leaching of Lithium Cobalt Oxide with Electrogenerated Leaching Agents from CO2, O2, and H2O

Abstract To leach the metals from lithium cobalt oxide (LCO) from batteries more sustainably, the application of electrochemically generated leaching agents from mainly CO2, O2, and H2O is presented. Therefore, CO2 was reduced to formic acid/formate and O2 was reduced to H2O2, each with high Faradaic efficiency (>85%) at gas diffusion electrodes. Formate and H2O2 were used individually or together to leach lithium and cobalt from LCO. When used together, mainly lithium was extracted while cobalt precipitated as insoluble cobalt phosphate, which allows efficient separation. Furthermore, lithium and cobalt could be leached almost quantitatively (Co: 99.6 ± 2.2%, Li: 92.7 ± 1.7%) by acidification with remarkably low amounts of sulfuric acid. In summary, this innovative feasibility study demonstrates that electrochemically generated leaching agents from air and water are a promising alternative to the conventional leaching methods.