Proton conductive nanoparticles coated with polymeric ionic liquids via RAFT polymerization with particles method for low-humidity proton conduction

Abstract

Proton conduction in the current polymer electrolyte membrane depends on water molecules, which necessitates high-humidity environments. On the contrary, proton conduction in low-humidity environments has been required for expanding operation conditions of polymer electrolyte fuel cells. Recently, ionic liquids (ILs) have been focused on novel proton conductive materials, however, the ILs were hard to fabricate the self-standing membrane owing to their fluidity. In this paper, we have developed composite materials composed of ILs and inorganic nanoparticles by coating ILs as polymer states (PILs) on the surface of nanoparticles. Notably, this material has obtained a powder form, and we have succeeded in suppressing the fluidity of ILs. The PILs-coated nanoparticles have achieved good proton conductivity over 10−2 S cm−1 at 95% RH, also indicated over 10−4 S cm−1 under 60% RH. In addition, we have clarified the relationship between the thickness of PILs and proton conductivities.