Synthesis and Characterization of Nafion/60SiO[sub 2]-30P[sub 2]O[sub 5]-10ZrO[sub 2] Sol-Gel Composite Membranes for PEMFCs

A limitation of Nafion membranes in proton-exchange membrane fuel cells (PEMFCs) is their poor water retention above 100°C. The incorporation of SiO 2 ­ P 2 O 5 ­ ZrO 2 gels into Nafion membranes can improve their thermal stability. Therefore, composite membranes were prepared either by infiltration of Nafion membranes with SiO 2 ­ P 2 O 5 ­ ZrO 2 sol or by recasting a film using Nafion solution and SiO 2 ­ P 2 O 5 ­ ZrO 2 sol. The membranes were characterized by thermal analysis, microstructural analysis, functional testing in a fuel cell, and electrochemical impedance spectroscopy. The incorporation of the SiO 2 ­ P 2 O 5 ­ ZrO 2 gel resulted in improved electrochemical behavior at 130°C, with current density-cell potential values as good as those obtained at 80°C with unmodified Nafion membranes. © 2005 The Electrochemical Society. All rights reserved.