Fast-Charging Li-Ion Battery Enabled by an Acetonitrile-Based Electrolyte

Abstract

Fast charging remains a critical challenge for current-generation lithium-ion batteries (LIBs), particularly in electric vehicle applications. In this study, we present a highly conductive electrolyte formulation based on a ternary solvent system consisting of acetonitrile (AN), fluoroethylene carbonate (FEC), and ethylene carbonate (EC), combined with a tailored additive, lithium difluoro(oxalato)borate (LiDFOB). This electrolyte demonstrates significantly enhanced ionic conductivity and a higher Li⁺ transference number, enabling accelerated Li⁺ transport kinetics. The synergistic effect of the solvents and the additive promotes the formation of a robust, low-resistance, inorganic-rich solid-electrolyte-interphase (SEI) that effectively passivates the graphite surface and suppresses AN decomposition. As a result, the electrolyte substantially reduces internal cell resistance and overpotential, both of which are critical for reliable fast charging. These findings highlight the essential role of rational electrolyte design in addressing the limitations of fast-charging LIBs.