Nafion-TiO2 hybrid electrolytes for stable operation of PEM fuel cells at high temperature

The fabrication and characterization of Nafion-TiO2 hybrid electrolytes for proton exchange membrane fuel cell (PEMFC) operating at high temperature are reported. A low temperature sol-gel synthesis, based on the formation of a sol from Ti-peroxy complex, was used to effectively incorporate hydrophilic anatase TiO2 nanoparticles into the Nafion matrix. Fuel cell testing at temperatures up to 130 oC revealed that the hybrid membranes exhibit an increasing ohmic drop with increasing TiO2 content incorporated into the polymer. However, at high temperatures and low relative humidity (RH) the performance of fuel cells using the hybrid electrolytes was found to surpass the one of Nafion. Electrochemical impedance spectroscopy (EIS) measurements suggest that enhancement of the fuel cell performance at high temperature and low RH is related to a reduced polarization resistance, indicating that the hybrid electrolytes contribute for a better water management of the system. In addition, it was found that the inorganic phase confers stability to the polymer, allowing for the operation at high temperature and reduced RH.