Boosting the proton conduction using protonated imidazole for advanced ion conducting membrane

Abstract

Fine-tuning the nanochannels of ion conducting membrane is the key to achieving high performance electrochemical devices. Here, we describe an effective way to enhance the membrane performance using heterocyclic imidazole compound as an additive for Nafion. The hygroscopic nature of the imidazole offered sufficient amount of water molecules to the nanochannel of Nafion, affording wider and continuous nanochannel configuration, as characterized by small angle X-ray scattering (SAXS). Moreover, proton conduction was boosted by the hydrogen bonding interaction between the water molecules and two nitrogen atoms on imidazole ring. The developed membrane showed improved proton conductivity up to 23% and 50% under high and low humidity condition, respectively, compared to pristine Nafion. Additionally, the membrane exhibited excellent stability under harsh condition. Finally, we implemented the developed membrane in fuel cell application and the cell showed enhanced power density without performance degradation, compared to that employing pristine Nafion membrane.