The US Air Force Phillips Laboratory lithium-polymer battery program

The US Air Force is examining lithium-polymer batteries as possible replacements for the Ag/ZnO primary batteries used in space launch vehicles. Li-polymer batteries possess some definite advantages over Ag/ZnO batteries: namely, an increase in energy density while retaining a similar specific energy, a reduction in the amount of liquid electrolyte, and a greatly extended "wet" shelf life. This combination of factors makes the Li-polymer battery a very attractive energy storage medium. In addition, Li-polymer batteries can be recharged if needed; in fact, 1.1 Ah test cell packs fabricated for this Air Force program have been cycled more than 10 times. Thus, if a launch needs to be scrubbed for any reason after the batteries have been partially or fully discharged, they need not be replaced. In an effort to address space power systems concerns, Phillips Laboratory has contracted with SAFT America and Binrad Industries, Inc. to develop a 150 Ah Li-polymer cell with a specific energy of 150 Wh/kg and a power density of 100 W/kg. The first hardware deliverables (four 1.2 Ah cell packs) are to be delivered in June 1997, with a 150 Ah cell pack to be delivered in June 1998. After the Air Force receives these batteries, they will undergo in-house testing.