High Power Bipolar Ni-MH Battery for More Electric Aircraft

The USAF's transition to More Electric Aircraft (MEA) will force greater demands on energy storage by rechargeable batteries. MEAs will rely on electrically based power systems to supplant the present combination of hydraulic, pneumatic, mechanical, and electrical subsystems, all of whose power are extracted from the main aircraft engines. However, a considerable battery energy storage capability will be needed for decentralized and backup (safety) power as well as power conditioning (load leveling) applications. Consequently, viable battery candidates will be characterized by high energy storage content and high power delivery abilities. The nickel-metal hydride (Ni-MH)system is now under study as a superior candidate for a wide range of applications, including such high power commercial applications as hybrid electric vehicles (HEVs). Electro Energy, Inc. is presently developing a patent-pending bipolar version of the Ni-MH system, based on the use of conductive polymers. This advanced design yields high energy density of 60-70 Wh/kg, a significant improvement above present conventional technologies. In addition, the bipolar geometry is especially well suited to high current density applications. The proposed project is directed at development of a high power version of this system that would ultimately yield power densities on the order of 200 W/kg. This will involve the development of both improved hydride materials with higher rate capability as well as optimization of cell components to minimize cell resistivity.