Study on the conductivity of recast Nafion/montmorillonite and Nafion/TiO2 composite membranes

Nafion^® composite membranes were formed from a recast procedure already applied by the authors. Montmorillonite (MMT) and titanium dioxide (TiO₂) were used separately as fillers in the recast process and dimethylformamide (DMF) was used as the casting solvent. Addition of 1 wt.% MMT or 1 wt.% TiO₂ to the ionomer dispersions prior to the heat treatment demonstrated that there is an increase in water content of the recast membranes. For both the samples, it was verified that the tangential conductivity increases with increasing relative humidity (RH) of the environment. Fuel cell tests carried out with recast membranes showed that the best performances are seen when the anode and cathode humidification temperatures are low. With a ΔT of −35 °C between cell temperature and anode humidification, the conductivity of additive-containing samples is 10% higher than that of additive-free membranes.