Showing papers on "Supercapacitor published in 1994"

High energy density and high power density ultracapacitors and supercapacitors

Abstract: Ultracapacitor and supercapacitor designs wherein two discrete metal film current collectors of the prior art, one for each of the cathode and anode, are replaced by a single thin polymer film. The polymer film is typically several microns thick and metallized on both sides. The thickness of the metallization is varied from several hundred to several thousand Ångstroms depending upon the particular application. This metallization serves as the positive and negative electrodes (current collectors) which are spatially separated by the polymer dielectric film. The resulting reduction of volume increases the volumetric energy density and the reduction of mass increases the gravimetric energy density. The electrolyte solvent/salt system can be selected to provide useful individual cell voltages as high as 5 volts. The voltage is limited only by the electrolytic stability of the solvent and salt. Ultracapacitors fabricated in accordance with the present invention may have energy densities exceeding 10 watt-hours per kilogram and volumetric energy densities exceeding 15 watt-hours per liter. Values which are yet higher are feasible with supercapacitors fabricated in accordance with the present invention.

Supercapacitor electrochemical cell

Abstract: The present invention provides a thin-film palladium electrode as a reversible redox-active positive electrode in a supercapacitor configuration. A room-temperature chloroaluminate molten salt composed of an organic chloride, mixed with a molar excess of aluminum chloride, is used as the supercapacitor electrolyte. In this electrolyte, the palladium surface can be reversibly oxidized to an insoluble thin-film of palladium chloride. Reduction of this palladium chloride thin film back to palladium metal, generates a high current density. The capacitance of this supercapacitor electrode is 150-550 times that of a double-layer capacitor electrode. By combining the thin-film palladium supercapacitor positive electrode (cathode) with a suitable negative electrode (anode), e.g. a metallic aluminum anode, a high power supercapacitor cell, capable of delivering a charge at high current density, at near constant voltage of ca.1 V, is provided per the present invention. The cell of the invention can accordingly provide power for devices requiring pulsed electric power, e.g. lasers and for numerous other systems of high current demand, e.g. starters for electric vehicles.

Ultracapacitors as sole energy storage device in hybrid electric cars

Abstract: New types of electric capacitors may provide, within several years, power capacitors which could be used as energy storage devices in serial hybrid electric car drives instead of a battery. This paper discusses how to determine the required size of such a capacitor used as the sole energy storage device. The performance requirements and parameters influencing the size of the capacitor are defined and a model of a hybrid car system is proposed to determine the size of the capacitor. Simulation results are presented to demonstrate the choices in selecting the capacitor size and to provide an estimate of the performance of a hybrid vehicle with capacitive energy storage.

Performance of Polymer-Based Supercapacitors

Abstract: Supercapacitors are now attracting much attention as an electric vehicle power source. The present study focuses on redox supercapacitors with electronically conducting polymers as electrode materials. Performance data of a symmetric supercapacitor based on p-doped poly(pyrrole), of an unsymmetric supercapacitor based on p-doped poly(pyrrole) and poly(3-methylthiophene), and of a symmetric sypercapacitor based on p- and n-doped poly(dithieno[3, 4-b:3′, 4′-d]thiophene) are here compared.