CsH2PO4/Polyvinylidene Fluoride Composite Electrolytes for Intermediate Temperature Fuel Cells

In this study CsH2PO4/polyvinylidene fluoride (PVDF) composite electrolytes were prepared by a slurry casting method and their application in intermediate temperature fuel cells (ITFCs) was investigated. The composite electrolytes consisted of a physical dispersion of CsH2PO4 particles in the PVDF polymer network and were thin and flexible. The crystalline structure and thermal behavior of CsH2PO4 were not influenced by the PVDF. The composite electrolyte with 70 wt% CsH2PO4 showed a high conductivity of 10 mS cm(-1) at 270 degrees C under 30% H2O/Ar atmosphere as well as a tensile strength of 7 MPa at room temperature. In addition, the composite electrolytes had area specific resistances of 0.99 and 0.72 Omega cm(2), for corresponding thicknesses of 101 and 67 mu m, which are low values. The composite electrolyte with 70 wt% CsH2PO4 showed stable conductivity at 259 degrees C under 30% H2O/Ar atmosphere for 48 h. A fuel cell assembled with this electrolyte exhibited an open circuit voltage of 0.92 V and a peak power density of 86 mW cm(-2), making the composite electrolyte a candidate electrolyte for ITFCs. (C) 2014 The Electrochemical Society. All rights reserved.