Preparation and characterization of sulfated zirconia(SO42-/ZrO2)/Nafion composite membranes for PEMFC operation at high temperature/low humidity

Fine particle superacidic sulfated zirconia (SO42-/ZrO2, S-ZrO2) was synthesized by ameliorated method, and composite membranes with different S-ZrO2 contents were prepared by a recasting procedure from a suspension of S-ZrO2 powder and Nation solution. The physico-chemical properties of the membranes were studied by ion exchange capacity (IEC) and liquid water uptake measurements, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, thermogravimetry-mass spectrometry (TG-MS) and Fourier transform infrared (Fr-IR) spectroscopy. The results showed that the IEC of composite membrane increased with the content of S-ZrO2, S-ZrO2 was compatible with the Nafion matrix, the incorporation of the S-ZrO2 could increase the crystallinity and also improve the initial degradation temperature of the composite membrane. The performance of single cell was the best when the S-ZrO2 content was 15 wt.%, and achieved 1.35 W/cm(2) at 80 degrees C and 0.99 W/cm(2) at 120 degrees C based on H-2/O-2 and at a pressure of 2 atm, the performance of the single cell with optimized S-ZrO2 was far more than that of the Nation at the same condition (e.g. 1.28W/cm(2) at 80 degrees C, 0.75 W/cm(2) at 120 degrees C). The 15 wt.% S-ZrO2/Nafion composite membrane showed lower fuel cell internal resistance than Nation membranes at high temperature and low relative humidity (RH). (c) 2006 Elsevier B.V. All rights reserved.