Recovery of organic electrolyte solvents from spent perforated Li-ion cells using a low-temperature vacuum-assisted distillation process

Abstract

Electrolyte solvent recovery is rarely addressed in current state-of-the-art lithium-ion battery (LiB) recycling processes, even though electrolytes are flammable, toxic, and hazardous. In conventional recycling processes, electrolytes typically evaporate or decompose uncontrollably during pre-treatment steps such as shredding, leading to both safety risks and environmental damage. To overcome these limitations, we investigated a controlled electrolyte solvent recovery process using mild-temperature vacuum distillation on perforated, intact batteries rather than shredded material. This method enabled safe handling and minimised uncontrolled emissions during pre-treatment. Analysis results demonstrate a successful 84 % recovery of the major electrolyte solvents, dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and ethylene carbonate (EC), after 300 min of thermal-vacuum treatment at 110 °C and 80 mBar vacuum pressure. Decomposition products of Lithium Hexafluorophosphate (LiPF₆), which include hydrogen fluoride (HF) and phosphoryl fluoride (POF₃), were not identified in the exhaust gas, and the scrubber solution remained neutral during operation. These results demonstrate that thermal treatment below 110 °C is a non-complex, feasible, and environmentally friendly process for recovering electrolyte solvents prior to metal recovery, addressing a major gap in current LiB recycling processes.