Recovery of compounds from Li-ion battery electrolyte

摘要

The present disclosure concerns the recovery of valuable compounds from electrolytes of the type found in Li-ion rechargeable batteries. The process for the recovery of lithium hexafluorophosphate, and organic carbonates from battery electrolyte, comprises the steps of:
- contacting the electrolyte with a phosphonium chloride-based ionic liquid, thereby forming a solid phase comprising LiCl, and a liquid phase comprising a phosphonium hexafluorophosphate-based ionic liquid and the organic carbonates;
- separating the solid and the liquid phases, thereby isolating LiCl;
- water-extraction of the organic carbonates from the liquid phase, thereby obtaining two immiscible liquid phases consisting of a first phase comprising an aqueous solution of the organic carbonates, and a second phase comprising the phosphonium hexafluorophosphate-based ionic liquid;
- separating said immiscible liquid phases, thereby isolating the phosphonium hexafluorophosphate-based ionic liquid;
- evaporating the water from the liquid phase comprising the aqueous solution, thereby recovering the organic carbonates. Thanks to the exploitation of suitable ionic liquids, lithium, hexafluorophosphate, and the organic carbonates are recovered at high yields. The process is clean and safe, as volatile organic solvents are totally avoided.