The feasibility of a pyrrolidinium-based ionic liquid solvent for non-graphitic carbon electrodes

The feasibility of a pyrrolidinium-based room-temperature ionic liquid (RTIL) as the solvent for lithium-ion batteries is tested by analyzing its intercalation behavior and thermal stability. The RTIL-cations are intercalated into a graphitic carbon and a part of them are irreversibly trapped inside the graphene layers. These trapped cations block Li+ intercalation to give only a marginal capacity. In contrast, such a cation insertion/trapping is absent in two non-graphitic carbons; hard carbon and soft carbon. A stable cycle performance with a Li+ insertion capacity of about 200 mAh g− 1 is attained. The absence of RTIL-cation insertion is evidenced by the cyclic voltammograms and Raman spectra. A calorimetric study reveals that this RTIL has a higher thermal stability and less reactivity with lithiated carbons as compared with the carbonate-based solvent. The use of this RTIL solvent for the non-graphitic carbons seems to be feasible.

► No intercalation of a pyrrolidinium-based ionic liquid into the non-graphitic carbon.
► Non-graphitic carbon electrodes in this ionic liquid show an excellent cycleability.
► Charged non-graphitic carbon electrodes exhibit a high thermal stability in this ionic liquid.
► The use of this ionic liquid is quite feasible for the non-graphitic carbon negative electrode.