Preparation of proton conductive composites with CsHSO4/CsH2PO4 and phosphosilicate gel

New composite materials were prepared using cesium hydrogen sulfate (CsHSO4) or cesium dihydrogen phosphate (CsH2PO4) and phosphosilicate gel (P2O5–SiO2 gel). In X-ray diffraction patterns of these composites, diffraction peaks due to Cs2H5(SO4)2(PO4) and CsH5(PO4)2 were observed for CsHSO4–(P2O5–SiO2 gel) composites and CsH2PO4–(P2O5–SiO2 gel) composites, respectively. These composites showed high conductivities in the order of 10− 3 S cm− 1 at 150 °C due to melting of Cs2H5(SO4)2(PO4) or CsH5(PO4)2 in the composites. In the cooling process, the CsHSO4–(P2O5–SiO2 gel) composites kept relatively high conductivity to 110 °C where solidification of Cs2H5(SO4)2(PO4) occurs, whereas CsH2PO4–(P2O5–SiO2 gel) composites showed relatively high conductivity continuously to ambient temperature.