A novel polybenzimidazole membrane containing bulky naphthalene group for vanadium flow battery

Poly[2,2’-(1,4-naphthalene)-5,5′-bibenzimidazoles] (NPBIs) were successfully synthesized in Eaton's reagent and first investigated as dense proton exchange membranes for vanadium flow batteries. The basic properties of NPBI were characterized and compared with poly[2,2’-(4,4′-oxybis(1,4-phenylene))-5,5′-bibenzimidazoles] (OPBIs) and Nafion® 212. NPBI displayed superior solubility in common aprotic polar solvents and hence eliminated the...