Supercritical CO2 extraction behavior of electrolyte solvents from Li-ion battery black mass

Abstract

Electrolyte recovery from spent Li-ion batteries remains a significant challenge in the current recycling process. Li-ion battery waste streams containing electrolyte residues are classified as hazardous waste and entail a financial and workplace safety burden for the recycling industry. Recent studies show the potential use of supercritical CO₂ extraction for the recovery of electrolyte solvents. In this study, the extraction behavior of electrolyte solvents from Li-ion battery black mass using supercritical CO₂ process under pressures of 100 and 140 bar at 40°C was investigated. The extraction yield of dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate exceeded 99 % at both pressures. Ethylene carbonate, biphenyl, and propylene carbonate were successfully extracted with an extraction yield exceeding 95 % using 140 bar and 40°C. The extraction rates of biphenyl, ethylene carbonate and propylene carbonate at 140 bar and 40°C in the linear extraction regime of the extraction curve were determined to be 0.18 mg/g CO₂, 1.9 mg/g CO₂ and 0.4 mg/g CO₂, respectively. The research demonstrates that supercritical CO₂ processing is a highly promising method not only for recycling electrolytes but also for mitigating the hazardous risks associated with battery waste.