A lactic acid dioxolane as a bio-based solvent for lithium-ion batteries: physicochemical and electrochemical investigations of lithium imide-based electrolytes

In this study we report for the first time the application of an emerging bio-based solvent derived from lactic acid, namely 5-methyl-1,3-dioxolane-4-one (LA-H,H), as an electrolyte component for lithium-ion batteries (LIBs). Electrolyte formulations consisting of this novel bio-solvent and imide conducting salts (i.e. lithium bis(trifluoromethanesulfonyl)imide, LiTFSI, and lithium bis(fluorosulfonyl)imide, LiFSI) and the additive vinylene carbonate (VC) are prepared and thoroughly evaluated. Resulting formulations demonstrate suitable transport properties (e.g., conductivity, viscosity) and considerably low flammability compared to standard electrolyte formulations. The compatibility of the novel imide-based electrolytes with benchmark active materials such as graphite (GR) and lithium iron phosphate (LFP) are explored. The results indicate that the use of LA-H,H-LiTFSI 1 M 5 wt% VC allows high electrochemical performance in terms of rate-capability and cycling stability for both the graphite (339 mA h g-1 at 1C) and the LFP (100 mA h g-1 at 1C) electrodes. The suitability of this novel electrolyte configuration was further demonstrated through the assembly of a lab-scale full-cell LIB showing remarkable rate capability and cycling stability. These results indicate that LA-H,H can be used as an electrolyte component for LIBs, and pave the way for its use as bio-based solvent in energy storage systems.