Over the past several decades, ionic liquids have been investigated as electrolytes for electrochemical devices due to their thermal stability (derived from their negligible vapor pressure), high ionic conductivity (arising from low viscosity), and high electrochemical stability. Here, we synthesized three ionic liquids with different cation structures including (methyl-piperidinium, methyl-morpholinium, tetraethylammonium) functionalized with lithium dissociating 1-methoxyethylgroups. The physical, and thermal properties of the three ionic liquids are conducted, with all exhibiting excellent thermal and electrochemical stability. Furthermore, the lithium ion transport behaviors in relation to the cation structures were demonstrated, which was directly reflected in the performance of a lithium ion capacitor.