This paper surveys the state-of-the-art of advanced electrochemical energy sources for space use.
For individual cases we have to decide between primary cells, secondary cells, and fuel cells.
Primary cells provide power needs for up to a few weeks and also serve as spare (reserve) batteries. Since 1960 the advanced alkaline silver oxidezinc batteries have been developed with a specific energy of 350 W h/kg, and during the last ten years the non-aqueous lithium battery has become a potential competitor with a specific energy of 450 W h/kg.
Secondary batteries will in the future continue to be the most important electrochemical energy source. We can distinguish between first (conventional), second (new) and third (non-aqueous) generations.
At present, the classical NiOOH/Cd battery is the only rechargeable system for use with solar cells in missions requiring long life (5 -10 years). Among the new systems, the best appears to be the hermetically sealed NiOOH/Hz battery. We expect a high-cycle life (> 10 000) and high energy density (up to 65 W h/kg). It will probably be introduced around the year 1980. All the non-aqueous lithium and sodium storage systems are still under development either in the single cell or the laboratory prototype stage.
For projects involving manned space flights the direct Hz/Oz fuel cell will continue to be in wide practical use. At present the power density is 50 -70 W/kg and the maintenance-free lifetime for alkaline systems is 2 000 -3 000 hours.