Battery Types – Sodium Nickel Chloride Battery
Sodium Nickel Chloride batteries use plain salt and nickel as the raw materials for their electrodes in combination with a ceramic electrolyte and a molten salt. The battery type, initially known as ZEBRA battery, has its roots in South Africa in the mid-1970s. Pioneering work by the ZEolite Battery Research Africa group was led by Dr. Johan Coetzer at the South African Council for Scientific and Industrial Research (CSIR) in Pretoria[2].
The salt decomposes in the molten salt electrolyte (NaAlCl4) to 2Na+ and 2 Cl–. The 2 Cl– react with nickel to form NiCl2 plus 2 electrons which are conducted to the positive pole. The 2 Na+ ions are conducted through the β”-Al2O3 wall to the sodium side where they combine with electrons to form the negative pole (sodium metal). These reactions occur upon charging of the battery. During discharge the process is inverted.[1]
The battery operates at temperatures of about 250°C which is often considered a roadblock hindering market penetration. However, the high operating temperature provides the advantage to operate independent of the ambient temperature and to provide infinite storability in the cold state.
A prominent example of a sodium nickel battery is the 540 kWh storage battery at Switzerland’s largest supermarket chain combined with a photovoltaic installation to make full use of the captive solar energy.
[1] Dustmann, C. H. Advances in ZEBRA batteries. J. Power Sources 127, 85–92
(2004).
[2] Arnold van Zyl, Review of the zebra battery system development, Solid State Ionics, Volumes 86–88, Part 2, 1996, Pages 883-889,
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