A.
Nickel hydrogen storage battery (NiH2 or Ni-H2) is a type of dry battery developed for the particular use as power source in satellites and other various space probes. It is a rechargeable electrochemical power source based on nickel and hydrogen. It differs from a nickel metal hydride (NiMH) battery by use of hydrogen in gaseous form stored in a pressurized cell at up to 1200 psi (82.7 bar) pressure.

Energy density is only around one third as that of a lithium battery. The distinctive virtue of the nickel-hydrogen battery is its long life, the cells handle more than 20,000 charge cycles with 85% energy efficiency and 100% faradaic efficiency. Such properties make them attractive for energy storage of electric energy with satellites and space probes.

Nickel hydrogen storage batteries are classified as dry battery and SP A123 applies.