3-6. Advanced Nickel-Hydrogen Batteries DAVID F. PICKETT Summary Development of nickel-hydrogen batteries has progressed to the point where the nickel-hydrogen battery is the secondary power source of choice for almost all satellite systems within the USA and it is also making inroads into European Space Agency programs. The technology has emerged in the form of two basic cell designs, one developed by COMSAT and the other by Hughes Aircraft under US Air Force sponsorship. Thus far, most of the spacecraft using this technology have been geosynchronous (GEO) commercial communications satellites. Nickel-hydrogen batteries are soon scheduled for a low Earth orbit (LEO) launch on the Hubble Space Telescope and on space station in the 1990s. There are a number of improvements in the nickel-hydrogen cell which indicate that its current LEO cycle life-performance can be extended by five times and its specific energy in GEO can be doubled or tripled. Background Work started in the USA in nickel-hydrogen batteries at COMSAT Laboratories in 1971 [1, 2, 3]. Soon afterwards, results of studies appeared on the feasibility of intergrating this type of battery, with its required pressure vessel, into a spacecraft [4]. A few years later both the US. Navy and Air Force demonstrated its feasibility in flight experiments [5, 6]. The first launch of a commercial spacecraft having nickel-hydrogen batteries (INTELSAT V) occurred in 1983 [7]. Since that time, there have been launches of several GEO commercial communications satellites. A history of flight experience up to 1988 has been given by Miller [7]. Initial development of the nickel-hydrogen cell proceeded with two different concepts: one sponsored by COMSAT aimed at use in GEO missions [3] and the other sponsored by the US Air Force and Hughes Aircraft with LEO missions as a goal [4], Neither design has been limited to consideration for only LEO or GEO missions; in other words, either cell is interchangeable for other orbits depending on thermal, weight, mission lifetime and other conditions. In the COMSAT design, electrode leads are run along the edges of the electrode stack and an asbestos separator is used. The pressure vessel is coated on the inside with Teflon. A Ziegler seal is used at electrode terminals [3]. In the Hughes/Air Force version, electrodes are designed in a ‘pineapple slice' configuration so that electrode leads can run through the center of the stack, allowing very short distances between the electrode stack and pressure vessel wall (0.050 in.) [8]. The separator of choice is Zircar, a zirconium oxide cloth manufactured by the Zircar Products Corporation in Florida, New York. The pressure vessel's David F. Pickett, Hughes Aircraft Company, Space and Communications Group, El Segunda, CA 90245, USA. Paper number IAF-COSP89-3-6.
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