Electrochemical capacitor using polymer/carbon composites

An electrochemical capacitor fabricated by thin-film techniques is described. The active principle is based on the electrical capacitance of a polymer electrolyte/carbon interface. The flexible multi-coating device (500 μm thick) consisted of a plasticized poly(ethylene oxide) lithium perchlorate electrolyte film, two carbon composite electrodes and large area collectors. The electrochemical and electrical properties of the components and the complete cell are presented. After 5000 operation cycles the device exhibited a maximum capacitance of 2.4 F cm−3 providing an energy density of 20 kJ l−1 with a peak power about 300 W l−1.