Polyvinyl alcohol-heteropoly acid polymer electrolytes and their applications in electrochemical capacitors

A solid polymer electrolyte with a poly (vinyl-alcohol) (PVA) matrix and a mixture of H3PW12O40 (PWA) and H4SiW12O40 (SiWA) as proton conductor was developed. The proton conductivity of this polymer electrolyte reached 0.013 scm− 1 at room temperature with a very low activation energy of 3.9 kJ mol− 1 at its optimal ratio (when SiWA and PWA were mixed in equal proportions). The room temperature proton conductivity was higher than that of pure PVA–PWA or PVA–SiWA electrolytes. The solid polymer electrolyte also showed good stability over time and at varying levels of relative humidity. A pseudocapacitor using this solid polymer electrolyte was demonstrated and showed good high rate performance and cycle life.