A Flexible CsH5(PO4)2-Doped Composite Electrolyte Membrane for Intermediate-Temperature Fuel Cells

Abstract

Based on CsH5(PO4)(2), sulfonated poly(ether ether ketone) (SPEEK), and phosphosilicate sol, proton-conducting CsH5(PO4)(2)/phosphosilicate/SPEEK composite electrolyte membranes have been prepared by a sol-gel method followed by mechanical ballmilling. The chemical structures, morphologies, thermal performances, stability, and proton conductivities of the composite electrolyte membranes were investigated. After incorporating the SPEEK polymer, these composite membranes exhibited adequate flexibility and mechanical performance; despite inorganic content of up to 80 wt%, a tensile strength of 6.2 MPa was maintained. Specifically, the composite electrolyte membrane displays a high proton conductivity of 14.6 mS cm(-1) at 250 degrees C under 47% H2O/N-2 atmosphere. A fuel cell equipped with the composite electrolyte membrane showed a stable output voltage over the continuous measurement of 50 h under a constant output current density of 40 mA cm(-2). (C) 2016 The Electrochemical Society. All rights reserved.