Microwave Assisted Ultrafast, Selective Lithium Extraction in Deep Eutectic Solvent for LIB Cathode Recycling

Abstract The exponential rise in the use of LIBs raises concerns over the supply chain of critical metals, e.g., Li, Co, and Ni, used in their cathodes. Deep Eutectic Solvents (DES) are considered as green lixiviants for hydrometallurgical recycling of cathodes to recover these metals, although their efficiencies are still not at par with conventionally used harsh inorganic solvents. Here it is demonstrated that when assisted by microwave, a choline chloride (ChCl): ethylene glycol (EG) based DES shows ultrafast selective extraction of Li from different commercially used cathode compositions, with a leaching efficiency of >50% in just 30 s and nearly 100% in ≈ 30 min. The ultrafast selective Li leaching can be attributed to microwave irradiation‐induced preferential non‐thermal activation of the polar ChCl in the DES. The rapid microwave approach allows time and energy‐efficient recovery of Li and also prevents the degradation of DES, as is seen in conventional prolonged high‐temperature procedures, and is able to extract Li from high solid/liquid concentrations of LIB cathodes in DES.