Solvometallurgical Recycling of Lithium-Ion Battery Cathode Materials Using Deep Eutectic Solvents and Ionic Liquids

Abstract As global society moves away from conventional fossil-based energy sources and towards greater electrification, the amount of waste lithium-ion batteries (LIBs) generated is only going to increase. This waste needs effective management and treatment to ensure that, at the very least, environmental damage and safety concerns can be minimized. Beyond this, ensuring that the critical materials can be recovered and recycled is an opportunity that should not be wasted. Here we present an experimentally verified proof-of-concept flowsheet for the dissolution of LIB cathode material, and subsequent separation of the dissolved metals using solvometallurgical methods. Leaching efficiencies of up to 100% for LiNi 0.33 Co 0.33 Mn 0.33 O 2 into the deep eutectic solvent (DES) choline chloride – ethylene glycol are possible using a novel electrochemical method. Non-aqueous solvent extraction was used to selectively separate the Co and Mn using Aliquat 336, followed by aqueous stripping. Manganese can be selectively recovered from the strip solution using bis-(2-ethylhexyl)-phosphoric acid dissolved in heptane. Final routes for the recovery of products used in battery cathode production are discussed based on verified literature and commercial methods, with recovery as Li 2 CO 3 , Ni(OH) 2 , Mn(OH) 2 , and Co(OH) 2 proposed. A presented proof-of-concept flowsheet shows the potential of the described novel dissolution technique, green solvents, and solvometallurgy for use in battery cathode recycling.