Proton conducting composite membrane from Daramic/Nafion for vanadium redox flow battery

A microporous separator (Daramic) was impregnated by soaking in a 5 wt.% Nafion solution to obtain a proton conducting composite membrane with modified properties for the vanadium redox flow battery (VRB). Nafion uptake by Daramic with thickness 0.25 mm is 6.5 wt.%. Infrared spectroscopy (IR), thermogravimetric analysis (TGA) and ion exchange capacity (IEC) have also been carried out to confirm incorporation of Nafion into the Daramic membrane. The new Daramic/Nafion composite membranes give acceptable low electrical resistance, although the measured area resistances are higher for the composite membranes with different thickness than that for the untreated membranes. A reduction in water uptake of the membranes is observed after impregnation. Open circuit voltage measurement with time of the proton conducting composite membrane showed promising results compared with that of the untreated Daramic membrane when used in the VRB.