Investigation Into the Properties of γ-Valerolactone and γ-Butyrolactone Imide-Based Electrolytes for Lithium-Ion Batteries

This study presents a detailed comparative study of lactone-based electrolytes (γ-valerolactone, GVL and γ-butyrolactone, GBL) combined with lithium imide-based salts, namely lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(fluoromethanesulfonyl)imide (LiFSI). Propylene carbonate is employed as a reference electrolyte solvent. The physicochemical properties of these electrolyte systems are determined experimentally and further calculated using our developed computational model. Besides, in-silico investigations are used to reveal valuable insights into the molecular interactions of the electrolyte components, such as self-diffusion coefficients and radial distribution functions. Furthermore, the suitability of lactone-based electrolytes for electrochemical applications is demonstrated by their promising rate capability and cycling stability over 200 cycles in graphite half-cells, especially with 1 M LiTFSI and 2 wt% vinylene carbonate, together with their favorable performance on lithium iron phosphate. An excellent capacity retention achieved in a full-cell configuration (> 80% after 200 cycles) further validates the potential of lactones as battery solvent alternatives, with GVL standing out due to its bio-based origin.