Proton conduction of in-situ formed Cs2H5(SO4)2(PO4) within phosphosilicate gel

► Proton conduction of composites composed of Cs2H5(SO4)2(PO4) and phophosilicate gel. ► The conductivity shows three distinct temperature dependences. ► Proton conducts through Cs2H5(SO4)2(PO4) within the pores of the phosphosilicate. ► The P-O-P bonds are newly formed between Cs2H5(SO4)2(PO4) and the phophosilicate. ► Scaling analysis proved the temperature-independent concentration of mobile protons.