Properties of the graphite-lithium anode in N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide as an electrolyte

The ternary [Li⁺][MPPip⁺][NTf₂⁻] ionic liquid, obtained by dissolution of solid lithium bis(trifluoromethanesulfonyl)imide (LiNTf₂) in liquid N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide (MPPipNTf₂), was used as an electrolyte, and stable at the lithium or graphite-lithium anodes. The graphite-lithium (C₆Li) anode showed good cyclability and Coulombic efficiency in the presence of a molecular additive (10 wt.% of vinylene carbonate, VC) to the ionic liquid. The electrode showed ca. 90% of its initial discharge capacity after 100 cycles. The addition of ethylene carbonate (EC) does not improve the cyclability of the anode to the same degree as that observed in the case of vinylene carbonate.