Ternary [Li+][MePrPip+][NTf2−] and [Li+][MePrPyrr+][NTf2−] room temperature ionic liquids (ILs) were obtained by dissolution of solid lithium bis(trifluoromethanesulfonyl)imide (LiNTf2) in liquid N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide and N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, respectively, and studied as electrolytes for the use in Li/LiFePO4 or C(Li)/LiFePO4 batteries. The cell worked properly in the presence of 10 wt% of vinylene carbonate (VC). Impedance-spectroscopy studies showed that the additive (VC) forms a protective coating on the anode. The LiFePO4 cathode shows good efficiency (135 mAh g−1) working together with [Li+][MePrPip+][NTf2−] + VC and [Li+][MePrPyrr+][NTf2−] + VC ionic liquid electrolytes. The flash point of ionic liquid electrolytes containing 10 wt% of VC is above 300 °C, which makes them practically non-flammable.