Cesium hydrogen sulphate and cesium dihydrogen phosphate based solid composite electrolyte for fuel cell application

Abstract

A new high temperature solid electrolyte composite was developed, with CsHSO4 and CsH2PO4 as the proton conducting material in composition with PTFE and SiO2 to enhance the solid electrolyte composites mechanical strength and conductivity. Conductivity measurements for CsHSO4 and CsH2PO4 and composites thereof, in temperature ranges 0 to 180 oC and 0 to 250 oC respectively, were carried out. The composites with different concentrations PTFE and silica were tested for stability in a enhanced conductivity. hydrogen atmosphere and different degrees of humidity. The CsHSO4 was seen to exhibit a super protonic phase change at temperatures between 132 – 140 C and CsH2PO4 around 230 C. The presence of the PTFE proved to be a stabilizing factor in the reduction of water re-adsorption once the membrane had been dried during thermal conductivity analysis. According to supporting data in the literature it has been found that composites including silica could be influenced by the hydrophilicity and specific surface area of the silica. In the composite system employed it was shown by impedance analysis the presence of two semi-circles in the Nyquist representation for the enhanced conductivity due the presence of silica.