An electrochemical capacitor includes a polymer thin film, a liquid
electrolyte absorbed in the polymer thin film, and thin flexible active
electrode layers constituting anode and cathode composed of energy dense
material of high intrinsic surface area positioned at either side of the
electrolyte-retaining polymer thin film to tightly sandwich it between the
electrode layers. In one embodiment, the capacitor includes a polymer
electrolyte in which a polymer thin film is cast from the base polymer and
impregnated with the electrolyte solution, which contains a salt for ionic
conduction. In another embodiment, the base polymer material includes an
ionically conducting polymer, a perfluorocarbon polymer backbone to which
sulfonic acid sites are permanently anchored. The energy dense material of
the electrode layers may be physically mixed with battery active material
to enhance the capacity and discharge time of the capacitor. In
fabrication, the electrode material is reduced to particle size suitable
for application to a thin film metallized polymer substrate, and applied
directly and adherently on opposite sides of the substrate by injection,
spraying, or evaporation, and a final thin flexible film of each electrode
is formed with a desired thickness by use of rods if a slurry, or by
controlling the extent of spray or evaporation, followed by curing. In
another embodiment, the electrode elements are laminated directly onto
opposite sides of a single- or double-metallized polymer substrate.
