Battery Types – Sodium Sulfur Battery

Like the previously discussed sodium nickel chloride battery, the sodium sulfur battery is a high temperature sodium battery. The Na-sulfur (Na–S) battery is a molten-salt battery consisting of a liquid sodium anode, a sulfur cathode, and an Al2O3 solid electrolyte. 

The electrode reactions can be described with following equations:

Anode             2Na <-> 2Na+ + 2e

Cathode          xS + 2e <-> Sx2-

Na–S cell principle operation during the discharge process[1]

A typical Na–S cell containing molten Na (anode) within a sodium alumina tube as the solid electrolyte which is surrounded by molten S (cathode). The cross-section of the cell shows the direction of Na+ transport through the alumina electrolyte. On discharge, Na combines with S to form Na polysulphides. These reactions are reversed during charging, and Na returns to the interior of the tube.

The first Na–S battery was invented at Ford in 1967. Sodium–sulphur batteries meet the requirements for economical, efficient and reliable stationary energy storage. The batteries exhibit reasonable power and energy densities, temperature stability, and low cost because of its abundant raw materials and suitability for high volume mass production. Other advantages of Na–S technology are cycling flexibility and low maintenance requirements. The Na–S batteries are available for grid applications, with 200 installations worldwide, accounting for 315 MW of discharge power capacity.[2]

[1] Hueso, Karina & Armand, Michel & Rojo, Teofilo. (2013). High Temperature Sodium Batteries: Status, Challenges and Future Trends. Energy Environ. Sci.. 6. 734-749. 10.1039/C3EE24086J.

[2] B. Dunn, H. Kamath and J.-M. Tarascon, Science, 2011, 334, 928–935.


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