Ion transport properties of block copolymer electrolytes comprising mixed ionic liquids.

Ionic conductivity and mechanical properties of block copolymers comprising various ionic liquids has been extensively studied lately to develop future solid-state polymer electrolytes. It has been found that the independent control of cation and anion in ionic liquid can improve ion transport properties of such materials given that the type of cation and anion determines swelling behavior of ionic domains and interfacial properties of ionophilic/ionophobic phases. In the present study, we investigate ion transport properties of block copolymers comprising different ionic liquids. In particular, by employing mixed ionic liquids, markedly improved ionic conductivity was obtained, far higher than simple sum of known values. The results were understood by dissimilar ion distributions in the substructure of self-assembled morphology, as quantified by combining scattering and spectroscopy techniques.