Nafion-sulfonated silica composite membrane for proton exchange membrane fuel cells under operating low humidity condition

Sulfonated silica, synthesized by using tetraethyl orthosilicate and chlorosulfuric acid through calcination, was used as a filler to create Nafion-SSA composite membranes for applying proton exchange membrane fuel cells under low relative humidity (RH)condition. High water uptake and ion exchange capacity values were observed, and the Nafion-SSA composite membrane showed improved proton conductivity than that of the recast Nafion. The fuel cell operating at 80 °C under 20% RH with Nafion-SSA composite membrane showed 2.8 times higher maximum power density (454 mW cm⁻²)and current density (2062 mA cm⁻²)in comparison with the recast Nafion (159 mW cm⁻², 734 mA cm⁻²). The thermal stability and mechanical properties of recast Nafion and Nafion-SSA composite membranes were evaluated by TGA and Tensile test.