Function and Characterization of Metal Oxide−Nafion Composite Membranes for Elevated-Temperature H₂/O₂ PEM Fuel Cells

Abstract

Metal-oxide-recast Nafion composite membranes were studied for operation in hydrogen/oxygen protonexchange membrane fuel cells (PEMFC) from 80 to 130 °C and at relative humidities ranging from 75 to 100%. Membranes of nominal 125 µm thickness were prepared by suspending a variety of metal oxide particles (SiO 2 , TiO 2 , Al 2 O 3 , and ZrO 2 ) in solubilized Nafion. The composite membranes were characterized using electrochemical, X-ray scattering, spectroscopic, mechanical, and thermal analysis techniques. Membrane characteristics were compared to fuel cell performance. These studies indicated a specific chemical interaction between polymer sulfonate groups and the metal oxide surface for systems that provide a good elevated-temperature (i.e., fuel-cell operation above 120 °C) performance. Composite systems that incorporate either a TiO 2 or a SiO 2 phase produced superior elevated-temperature, lowhumidity behavior compared to that of a simple Nafion-based fuel cell. Improved temperature tolerance permits the introduction of at least 500 ppm CO contaminant in the H 2 fuel stream without cell failure, in contrast to standard Nafion-based cells, which fail below 50 ppm of carbon monoxide.

Sulphonated poly ether ether ketone/amino‐diphenylsilandiol composite electrolyte for PEM fuel cells

“…This behavior can be attributed to the increase in membrane water retention at high temperatures (above 100 C) in the presence of the filler (NDPSD). The loss of water observed at elevated temperatures may be caused by a change in polymer structure and not by direct evaporation of water from the electrolyte, 30 so in this case the acid-base interaction between filler and SPEEK allows to maintain the SPEEK self-assembled structure through the high values of the operating temperatures studied here (100 C).…”

Polymer Nanocomposites - Fuel Cell Applications

“…The cell voltage of 5 wt.% silica composite membrane was increased due to the lower methanol crossover (Jiang et al 2006). There after number of efforts and patents (Adjemian et al 2006)has been filed on the modification of Nafion with hygroscopic oxides. Other hygroscopic oxides such as titania, alumina and zirconia were also extensively utilized for the modification of Nafion.…”

Embedding of Hollow Polymer Microspheres with Hydrophilic Shell in Nafion Matrix as Proton and Water Micro-Reservoir

“…Incorporation of inorganic particles (e.g., silica, zeolites) into Nafion membrane matrix to enhance hygroscopy of membrane is representative of earlier efforts [4][5][6][7][8][9][10]. In the resulting composite membrane, hydrogen bonding between the surface hydroxyl group of inorganic filler and the pendant sulfonic acid group (-SO 3 H) of Nafion assists the dispersion of filler particles in the host matrix [11,12]. Grafting hydrophilic oligomeric chains to inorganic particles [3][4][5][6][7][8][9][10][11][12][13][14][15] has furthered the preparation technique of Nafion nanocomposite membranes.…”

“…In the resulting composite membrane, hydrogen bonding between the surface hydroxyl group of inorganic filler and the pendant sulfonic acid group (-SO 3 H) of Nafion assists the dispersion of filler particles in the host matrix [11,12]. Grafting hydrophilic oligomeric chains to inorganic particles [3][4][5][6][7][8][9][10][11][12][13][14][15] has furthered the preparation technique of Nafion nanocomposite membranes. With the aim of achieving the forestated goal, use of hydrophilic hollow polymer spheres (HPS) as filler is apparently more attractive [16][17][18][19][20][21] because this particulate structure possesses larger interior space for storing water and the porous hydrophilic polymeric shell prevents quick evaporation of water while the membrane is subjected to dehydration [22,23].…”