Preparation, characterization and proton transport of new porous nanocomposite membranes based on polybenzimidazole, lignin and TiO 2 nanoparticles for high temperature PEM fuel cells

The high-temperature porous nanocomposite membranes based on polybenzimidazole and lignin with incorporation of TiO2 nanoparticles with high acid retaining ability were prepared and used in fuel cell. The effect of adding TiO2 nanoparticles was investigated on micro structure and physical properties of PBI membrane. The TiO2 nanoparticles prevent of open-surface micro-pores formation and the evaporation of phosphoric acid at high temperature from PBI matrix. The number of open voids within the nanocomposite membranes was reduced by increasing the content of TiO2 nanoparticles in membrane. Therefore, the proton conductivity of the nanocomposite membranes enhanced due to increasing of acid storage ability at the high temperatures. At temperature of 160°C, the proton conductivity of the nanocomposite membrane obtained 176 mS/cm. The power density of 0.58 W/cm2 was achieved for PBI-lignin-TiO2 nanocomposite membranes (lignin/PBI: 20 and 5.5 wt.% of TiO2) at 0.5 V and 180°C under dry condition, which confirmed that these developed membranes have high performance.