Alternative hybrid electrolytes based on a series of bis(trialkoxysilyl)alkanes and 3-(trihydroxysilyl)-1-propane sulfonic acid applied in gas diffusion electrodes of proton exchange membrane fuel cells

作者：Lin C W^*; Chung L C; Veerapur R S; Yang F C

来源：Journal of Power Sources, 2011, 196(3): 1069-1077.

DOI：10.1016/j.jpowsour.2010.08.024

• Fuel cell
• Gas diffusion electrodes
• Hybrid electrolytes
• Catalyst layer
• Microstructure

This study demonstrates a method for improving the electrolyte distribution in catalyst layers and enhancing the utilization of catalyst existing in primary pores. Bis(trialkoxysily)alkanes(BTAS-alkanes) and 3-(trihydroxysilyl)-1-propane sulfonic acid (THS)Pro-SO(3)H) precursors have been used to prepare a series of hybrid electrolytes with various organic segment lengths of BTAS-alkanes and ratios or organic moiety and sulfonic acid groups. Investigations of BTAS-alkanes series includes bis(triethoxysilyl)octane(BTES-Oct), bis(trimethoxysilyl)hexane (BTMS-Hex), and bis(triethoxysilyl)ethane (BTES-Eth). Small angel X-ray spetroscopy (SAXS) identifies morphological phase separation in BTES-Oct and BTMS-Hex hybrid electrolytes. The results of mercury porosimetry and BET porosimetry show that the hybrid electrolytes have better capability than Nafion ionomer to penetrate into primary pores of the catalyst layers. Electrochemical measurements including electrode polarization, electrochemical active surface (EAS) and electrochemical impedance spectroscopy (EIS) are discussed. The BTES-Oct or BTMS-Hex hybrid electrolytes with higher ratio of organic moiety and sulfonic acid group have achieved better electrode performance. Oxygen benefit current(OBC) results indicate that higher ratios of BTES-Oct/(THS)Pro-SO(3)H provides higher hydrophobicity with better gas transport properties. However, the hybrid electrodes exhibit lower cathode performance than Nafin (R)-based electrodes due to excessive incorporated in the catalyst layer.

• 出版日期2011-2-1