Polymer electrodes doped with heteropolymetallates and their use within solid-state supercapacitors

Redox-composited polymers have been chemically fabricated via vapour transport of monomer and evaluated for potential use as electrodes within a solid-state supercapacitor. An in depth evaluation of membrane electrode assemblies (MEAs, capacitor devices without a casing) was carried out. MEAs were made by hot pressing of the electrodes onto a proton-conducting solid electrolyte membrane in a ‘sandwich’ configuration. The highest specific capacitance, specific energy and specific power values depend on the method of cell-to-cell comparison: the highest values per unit mass of MEA were with electrodes incorporating polypyrrole doped with 10-molybdo-2-vanadophosphoric acid and stored wet (specific capacitance, specific energy and specific power values: 7 F g −1, 0.5 W h kg −1 and 3.3 W kg −1); the highest values per unit mass of active polymer were for polypyrrole doped with 12-molybdosilicic acid (33.4 F g −1, 2.12 W h g −1 and 3.7 W kg −1).