Showing papers on "Supercapacitor published in 1992"

Electrical system for a motor vehicle, including at least one supercapacitor

Abstract: The system includes at least one auxiliary electrical user device which, in order to be activated, needs a high power for a short period of time, a rechargeable battery, an electrical generator for recharging the battery and at least one supercapacitor for storing enough energy to activate the user device The connection of the supercapacitor to the user device is controlled by an electronic unit in dependence on the charge state of the supercapacitor and the temperature of the user device.

Proton exchange membrane electrochemical capacitors and fuel cells for pulse power applications

Abstract: An all-solid-state proton exchange ionomer-based electrochemical capacitor that represents a potentially more volume and weight effective, reliable, safer, and longer life alternative to the typical liquid electrolyte electrochemical capacitor systems was developed. The authors describe the approach used to increase the capacitance per unit weight and area of these electromechanical devices through the development and ionomer coating of 5- to 20-AA RuO/sub 2/ particles, dispersed on high-surface-area carbon and alternative substrates. Also, some comparative test results are presented on the use of advanced solid-ionomer high-energy-density fuel cell devices for pulse power applications. >

Nonaqueous thin film batteries and 'supercapacitors' employing Li/LiMO/sub x/ redox couples

Abstract: The technological requirements for burst power, high-energy-density memory backup, and a revitalized domestic electric vehicle program have suggested the use of thin-film, high-voltage transition metal oxide cathodes coupled with a Li foil anode in a bipolar configuration. Consequently, the authors investigated the electrochemical behavior of LiMn/sub 2/O/sub 4/, LiNiO/sub 2/, and LiCoO/sub 2/ prepared by chemical vapor deposition and sol-gel techniques. They consider the synthesis, characterization, and costs associated with the preparation of thin-film cathode materials. Particular attention has been focused on morphology, double-layer capacitors, and solid-state Li/sup +/ ion diffusivity as these materials are pulse discharged. >

The aerocapacitor: A carbon aerogel based supercapacitor

Abstract: During the 1980`s, a wide variety of carbon foams, formed by the pyrolysis of polymeric foams, were developed at several Department of Energy Laboratories. These foams are known for their monolithic structure and the ability to tailor their critical parameters (e.g. porosity, density). Lawrence Livermore National Laboratory (LLNL) exclusively developed a unique type of carbon foam, known as carbon aerogels. Carbon aerogels are a special class of open-cell foams with (1) homogeneous ultrafine particle and pore size, (2) very large useful surface area per unit volume, and (3) monolithic structure, that yields (4) excellent electrical conductivity due to the intimate connection of the particles. We have applied carbon aerogels to make an ``Aerocapacitor``; a high power- and energy-density electrochemical double layer capacitor (EDLC) that uses carbon aerogels as electrodes. Carbon aerogel surface areas range from about 100 to 700 m{sup 2}/cc (as measured by BET analysis), with bulk densities of 0.05 to 1.0 g/cm{sup 3} and their morphology allows stored energy to be released rapidly, resulting in high power-densities.

Acceleration coefficient of the molded electric double layer capacitor

Abstract: Molded-type electric double-layer capacitors (EDLCs) have been developed which are applicable for autoinsertion machine use and withstand solvent after soldering. Reliability tests on molded-type EDLCs were performed, and the reliability of these capacitors was found to be excellent. Load life tests were conducted at six level temperatures. Consequently, one could show the acceleration coefficient from failure rate at a certain temperature. >

Electrolytic Capacitors with a Conducting Polymer

Abstract: In this paper we describe the characteristics of a new type of aluminum electrolytic capacitor in which an electroconducting polymer is used as an electrolyte. A thick layer of polypyrrole is deposited on the alumina surface (dielectric) by chemical oxidative poly condensation in aqueous solution. By a precise controle of the deposit conditions of the polymer we demonstrate the possibility of a good coverage of the etched and anodized aluminum substrate. This is the condition required to obtain a high specific capacitance value. The final capacitor device has excellent impedance-frequency characteristics comparable to the ceramic capacitors. Film stability has been studied for polymers synthesized with different doping ions. It was found that increasing the molecular size of the counter-ion improves the stability of these aluminum electrolytic capacitors.