Abstract: A propulsion energy storage system for a hybrid vehicle includes ultracapacitor based energy storage to provide rechargeable energy storage. The rechargeable energy storage used performs well over a wide thermal range and thus permits vehicle designers and manufacturers to forego incorporation of temperature management systems. Further, as the rechargeable energy storage exhibit excellent thermal stability, the form factor of the cells of the rechargeable energy storage (e.g., ultracapacitors) may be adjusted to meet the desires of designers, manufacturers and users.

Abstract: An ultracapacitor includes at least one electrode that includes carbon nanotubes. The carbon nanotubes may be applied in a variety of ways, and a plurality of layers may be included. Methods of fabrication of carbon nanotubes and ultracapacitors are provided.

Abstract: A power system adapted for supplying power in a high temperature environment is disclosed. The power system includes a rechargeable energy storage that is operable in a temperature range of between about seventy degrees Celsius and about two hundred and fifty degrees Celsius coupled to a circuit for at least one of supplying power from the energy storage and charging the energy storage; wherein the energy storage is configured to store between about one one hundredth (0.01) of a joule and about one hundred megajoules of energy, and to provide peak power of between about one one hundredth (0.01) of a watt and about one hundred megawatts, for at least two charge-discharge cycles. Methods of use and fabrication are provided. Embodiments of additional features of the power supply are included.