Intercalation Chemistry of Ionic Liquids

The use of ionic liquids as electrolytes for the intercalation of TiS2 by Li+ and Mg++ has been studied using a short chain and long chain substituted imidazolium based ionic liquid: 1,2-dimethyl-3-n-propylimidazolium and 1,2-dimethyl-3-n-ocylimidazolium, both paired with the bis(trifluoromethanesulfonyl) imide anion. Results indicate co-intercalation of the shorter chain ionic liquid with the Li+ cation, while intercalation into TiS2 was not observed for the longer chain ionic liquid. For the longer chain system, intercalation of TiS2 by both Li+ and Mg++ is observed. Intercalation behavior is characterized by electrochemical and x-ray powder diffraction studies of the intercalates. Charge/discharge efficiencies for the shorter chain ionic liquid were typically below 50%, likely due to co-intercalation of the ionic liquid itself. Charge/discharge experiments of Li+ and Mg++ intercalation into TiS2 using the longer chain ionic liquid resulted in efficiencies over 90 %.