Low Cost, High Power Electrochemical Capacitor

A high power electrochemical capacitor is proposed based on low cost carbon materials. Currently, most commercial electrochemical capacitors use synthetic polymer precursors in the fabrication of activated carbon used in the electrode structures. Thesematerials offer superior performance over the life of the capacitor. The synthetic materials have high carbon purity, which leads to long life characteristics in the capacitor. Lower cost non-synthetic precursors are considerably less expensive buttypically do not exhibit stable performance over the life of the device. New and innovative manufacturing techniques for low cost precursors will be investigated that improve carbon purity. Currently, carbon constitutes 45% of the material costs inelectrochemical capacitors. The proposed improvements will reduce material cost by a factor of two. This dramatic reduction in material expense will improve the competitiveness of this technology in relation to rechargeable batteries. The developedmaterials will be integrated into high power electrode designs that will increase peak power performance by at least a factor of six. There is growing interest in the use of electrochemical energy storage systems during short-term power pulses. Commercialapplications include: regenerative braking in hybrid and electric vehicles, digital wireless telecommunication systems, and combustion engine starting applications. The short output characteristics of these applications differ from the duty cycles thanare typically seen for conventional battery systems. Electrochemical capacitor technology offers distinct advantages for these short pulse applications. They offer excellent reliability, cycle performance, and low temperature discharge characteristics.For many applications ranging from a faction of a second to 6 second pulses, an electrochemical capacitor offers a reduction in overall system size. Currently, because of the high cost of materials used in these capacitors they do not offer an advantagein cost in comparison to other technologies. The proposed development program will help alleviate this issue by reducing carbon cost by a factor of two.