Li-ion Battery Recycling by Energy-Efficient, High Throughput Li2SO4 Salt Splitting in a Diaphragm Flow Cell

Rapidly growing demand for lithium-ion batteries (LIBs) necessitates a significant expansion of LIB recycling to ensure adequate supply and reduce environmental burdens. Traditional hydrometallurgical LIB recycling processes use superstoichiometric quantities of acid and base and generate large volumes of salt waste. Electrochemical regeneration of acid and base from salt offers a zero-waste alternative but faces challenges with respect to throughput and energy consumption. This study reports a hydrometallurgical process to recycle lithium cobalt oxide (LCO) and lithium nickel manganese cobalt oxide (NMC) cathodes using acid and base electrochemically generated from a Li2SO4 electrolyte. The electrochemical cell used contains no ion exchange membranes, enabling excellent energy efficiency between 0.033 - 0.097 kWh/mol at current densities up to 500 mA/cm2 and imparting a robust tolerance for impurities that typically foul IEMs. The produced acid and base are found to be competent for etching and recovering >90% of the valuable metals from LIBs at industrially relevant pulp densities up to 66 g/L, and are readily regenerated from the salt solution left at the end of the metal recovery process.