Low-temperature (<0 degrees C) applications of Li-ion batteries have prompted the search for improved, high-conductivity electrolytes. Because the performance of the carbonaceous anode is highly sensitive to changes in electrolyte composition, we focused our efforts on this electrode. Electrolytes containing LiAsF5, LiPF6, LiN(SO2CF3)(2) [lithium bis(trifluoromethanesulfonyl)imide] , or LiIm, and LiC(SO2CF3)(3) [lithium tris(trifluoromethanesulfonyl)methide], or LiMe, in methyl formate (MF)-ethylene carbonate (EC) solvent mixtures were tested in lithium-graphite half-cells. The graphite electrodes could be cycled at ambient temperature with high reversible capacity. The best supporting electrolyte was found to be LiAsF6, and the presence of a high concentration of ethylene carbonate and up to 300 ppm H2O in the solution considerably increased the reversible capacity upon cycling. The conductivity values of a binary solvent mixture of methyl formate and ethylene carbonate containing LiAsF6 or LiMe were measured between -40 degrees C and room temperature. Graphite electrodes cycled at -2 degrees C in these electrolytes obtained reasonable reversible capacity, approaching 50%.