Sulfone-functionalized imidazolium ionic liquids were synthesized from direct nucleophilic substitution for the first time. Detailed NMR analysis of the products revealed the competition pathways of classic S(N)2 substitution and E2 elimination in the synthesis reaction. Impurities from E2 elimination can easily be overlooked during the conventional method of ionic liquid preparation via S(N)2 substitution. Initial electrochemical examination of the synthesized ionic liquids shows good compatibility with Li-1.1 (Ni1/3Co1/3Mn1/3)(0.9)O-2 cathode material. Published by Elsevier Ltd.