Coupling the Peroxydisulfate Electrosynthesis with Batch and Semi-Continuous Leaching Processes of Different Battery Cathode Materials

Abstract Different approaches to combine electrochemical peroxydisulfate production with efficient leaching of cathode material from lithium-ion batteries are demonstrated. Leaching of LCO, NCM, and black mass was investigated with well-established batch leaching as well as less common semi-continuous leaching. For this purpose, peroxydisulfate is converted to peroxymonosulfate and hydrogen peroxide via temperature-controlled hydrolysis reactions to improve the leaching outcome. Each leaching method is matched with a suitable peroxydisulfate production method (multi-pass or single-pass) and a heat conversion step. The conversion of peroxydisulfate to a mixture of peroxymonosulfate and/or hydrogen peroxide at 65 °C will enhance the leaching of LCO and NCM significantly for batch (s/l = 50 g L–1) and semi-continuous leaching. While batch leaching of NCM results in complete conversion of all metals after 1 h, semi-continuous leaching yields 30% of the transition metals and 50% of lithium with the potential for complete conversion by further addition of reagents, whereas using black mass (s/l = 200 g L–1) results in complete leaching of all metals with both approaches without applying an external heating.