High-Performance Carbon Materials for Ultracapacitors

65805 High rate energy storage devices, such as ultracapacitors, are a critical enabling technology for hybrid electric vehicles (HEV). The best electrode materials for use in electric double-layer capacitors (EDLC) possess three characteristics: (1) high surface area; (2) high electrical conductivity; and (3) surface area easily accessible by electrolyte. While ruthenium-based ultracapacitors exhibit almost ideal characteristics, the ruthenium was found to be too expensive for the large-scale manufacture of ultracapacitors. As an alternative, specialty carbon materials could satisfy these characteristics at reasonably low cost, provided that the pore-size distribution could be controlled. This project will develop high-performance carbon materials for ultracapacitors, using a proprietary carbon manufacturing technique that would ensure good control over the critical characteristics. Phase I demonstrated that the proprietary carbon material exhibited a capacitance per unit weight of ~100-200 F/g, up to ~30% better than the capacitance of the best cabon-fiber electrodes currently used. On a per-unit-volume basis, the electrodes were 3-4 times better than the reference electrodes. A preliminary economic analysis indicated cost reductions 4-10 times lower. In Phase II, an extensive parametric study will be performed with the purpose of optimizing ultracapacitor performance and cost. In addition, a series of prototype HEV ultracapacitors will be constructed and evaluated. Commercial Applications and Other Benefits as described by the awardee: A robust, versatile technique for manufacturing inexpensive, high-performance carbon ultracapacitors should have primary applications in hybrid power systems for electric cars and in fuel cells. Additional applications include high rate, short pulse delivery of large charges (such as pulsed lasers); power-supply low-frequency smoothing; and a variety of military, medical (defibrillators), telecommunications, and computer systems.