Formulation and Recycling of a Novel Electrolyte Based on Bio‐Derived γ‐Valerolactone and Lithium Bis(trifluoromethanesulfonyl)imide for Lithium‐Ion Batteries

This work introduces a novel electrolyte comprising lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt dissolved in bio-based γ-valerolactone (GVL) for lithium-ion batteries (LIBs). Moreover, a simple and sustainable aqueous-based recycling approach for recovering the imide-based lithium salt is proposed. Beyond the sustainable origin of the GVL solvent, this electrolyte exhibits reduced flammability risk, characterized by a flash point of 136 °C, along with favorable transport properties (conductivity of 6.2 mS cm−1 at 20 °C) and good electrochemical stability (5.0 V vs Li+/Li). Its good compatibility with graphite and lithium iron phosphate electrodes ensures remarkable cycling stability in LIB full-cells after 200 galvanostatic cycles at 1 C. Furthermore, the proposed liquid–liquid phase electrolyte recycling method allows for a nearly complete recovery of the LiTFSI salt (97–99%) and the GVL solvent (78%). The feasibility of the recycling process is validated by the reutilization of the recovered LiTFSI salt in electric double-layer capacitors, achieving performances similar to that of the pristine salt with exceptional long-term stability.