Graphite and LiCo1/3Mn1/3Ni1/3O2 electrodes with piperidinium ionic liquid and lithium bis(fluorosulfonyl)imide for Li-ion batteries

A new ionic liquid-based electrolyte for lithium batteries operating at an elevated temperature of 55 °C was prepared by combining N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP13TFSI) and lithium bis(fluorosulfonyl)imide (LiFSI). The electrolyte does not contain volatile organic components and is thermally stable (up to 285 °C) and ionically conductive (2.6 mS cm−1 at 55 °C). The 0.7m LiFSI–PP13TFSI electrolyte has been shown to work effectively with a graphite anode due to the ability of the FSI anions to create a stable solid electrolyte interface on graphite. A discharge capacity of 340–345 mAh g−1 was achieved at C/10 rate with a coulombic efficiency of 97–98%. The electrolyte is also compatible with LiCo1/3Mn1/3Ni1/3O2 (NMC) cathode material. At the C/10 rate, we achieved a discharge capacity of 160 mAh g−1. The coulombic efficiency remains high above 99%.

► Improved electrolyte for lithium-ion batteries operating at elevated temperature.
► Reversible lithium intercalation from ionic liquid-based electrolyte into graphite.
► Electrolyte compatible with graphite and LiCo1/3Mn1/3Ni1/3O2 at 55 °C.
► Aluminium current collector compatible with FSI and TFSI anions.