Silica alcogel-based proton conducting solid–liquid electrolyte composite

Silica alcogels doped with proton conducting salts (NH4BF4 or NH4H2PO4 or KH2PO4) have been prepared by sol–gel process starting from organic precursor tetraethyl orthosilicate (TEOS). Structural (IR, XRD, DSC) and electrical (transference number and conductivity) studies showed that the solutions of dopants salts remain entrapped in the porous SiO2–gel matrix giving a solid–liquid electrolyte composite material. An implication of the formation of solid–liquid electrolyte composite, apart from liquid-like conductivity, is that the slow drying of entrapped electrolyte solution on storage for 3–4 weeks results in the growth of whiskers of the dopant salt.