Compared to the commercially used state-of-the art non-aqueous organic carbonate solvent-based electrolytes, acetonitrile (AN)-based electrolytes have the advantage of enabling higher conductivity and lower viscosity values. The beneficial influence of adding fluoroethylene carbonate (FEC), thus enabling AN compatibility with graphite anodes, in different ratios to AN-based electrolytes represents the main focus of this manuscript. Long-term cycling measurements at 0 °C and 20 °C as well as conductivity and electrochemical stability measurements were performed to identify the optimal AN:FEC ratio. The electrochemical performance as well as the decomposition products were further investigated in graphite/lithium iron phosphate (LFP) cells to validate the applicability in lithium-ion cells.