Porous-Nafion/PBI composite membranes and Nafion/PBI blend membranes for vanadium redox flow batteries

Abstract Although Nafion membranes have a high chemical stability against VO2+ and a low resistance, their low coulomb efficiency (CE), due to crossover of vanadium cations, should be addressed. PBI membranes are chemically stable and effectively block vanadium cations, but have a lower conductivity than Nafion. Here we describe the fabrication of layered membranes, which consist of a 40 µm thick porous Nafion layer and a 2–17 µm thin PBI blocking layer. To promote adhesion, a