NOVELTY - The solid state energy storage device comprises a first electrode (12), a second electrode (14), a separator membrane (16) between the first and second electrodes, a first electrolyte present in contact with the first electrode and the separator membrane, and a second electrolyte present in contact with the second electrode and the separator membrane. The first electrolyte and the second electrolyte comprise a polyethylene oxide solvent, a lithium salt, a ferrocene mediator, and sulfonated tetrafluoroethylene based fluoropolymer-copolymer solvent.    USE - The solid state energy storage device such as battery, electrochemical capacitor, electric double layer capacitor and pseudo-capacitor is useful in electronic system.    ADVANTAGE - The solid state energy storage device can be economically with high durability and conductivity, increased specific energy and capacitances, increased charge storage capacity, reduced size and improved performance.    DETAILED DESCRIPTION - The solid state energy storage device comprises a first electrode (12), a second electrode (14), a separator membrane (16) between the first and second electrodes, a first electrolyte present in contact with the first electrode and the separator membrane, and a second electrolyte present in contact with the second electrode and the separator membrane. The first electrolyte and the second electrolyte comprise a polyethylene oxide solvent, a lithium salt, a ferrocene mediator, and sulfonated tetrafluoroethylene based fluoropolymer-copolymer solvent. The separator membrane is non-conductive, permeable to the dissociated salt ions and impermeable to the mediator, and has a thickness of 25-50 mm. The mediator of the first electrolyte is comprised of a reduced species of a molecule, and an oxidized species of the molecule in a ratio of ten reduced molecules to one oxidized molecule. The mediator of the second electrolyte is comprised of a reduced species of a molecule, and an oxidized species of the molecule in a ratio of one reduced molecule to ten oxidized molecules. The first electrode and second electrode are comprised of a material consisting of porous carbon monoliths, carbon powder, carbon fiber, carbon cloth, carbon film, carbon aerogels, carbon nanotubes, carbon foam, carbon nanofibers, graphite, porous aluminum oxide and porous titanium oxide, and comprise a mixture of activated carbon foam and carbon powder. An INDEPENDENT CLAIM is included for a method of forming a solid state energy storage device.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a solid state energy storage device.    First electrode (12)    Second electrode (14)    Membrane separator (16)    Solid state electrolyte (18)    First current collector (22)    Second current collector. (24)