Fresh Opportunity for the Sodium–Sulfur Battery

Sodium–sulfur batteries made their first major appearance in 1966 when automobile manufacturer Ford presented the battery to experts as a possible power source for electric cars.

However, over the last ten years, research into sodium–sulfur batteries has regained significance. Researchers worldwide are looking for alternatives to the lithium-ion batteries that currently dominate the market, as lithium is expensive and it has come under criticism due to the negative environmental impacts of lithium mining. The same applies for the metal cobalt, which is used in many lithium-ion batteries.

There is one factor, however, complicating the economic viability of sodium-sulfur batteries: they only work to a satisfactory level at temperatures of above 250 °C; at lower temperatures, too few charge carriers migrate from one pole to the other.

Dr. Tietz’s team has found an approach to ensure that sufficient charge carriers are also able to migrate at room temperature. To do so, the researchers made two adjustments. The decisive change they made was a considerable reduction in the thickness of the electrolyte. “The area-specific resistance of the solid electrolyte decreases tenfold if it is only a tenth as thick as usual,” explains Dr. Tietz. The researchers also optimized the contact possibilities between the electrolyte and the two poles of sodium and sulfur, respectively. Instead of producing the electrolyte from a single layer as usual, the Jülich researchers constructed it like a sandwich consisting of three layers: a more stable, dense middle layer surrounded by two porous layers. Sodium and sulfur can be stored within these layers, which improves the contact between the electrolyte and the electrode materials and, in turn, the energy density of the battery.

For further information, please refer to the corresponding publication on the homepage of Forschungszentrum Jülich: https://www.fz-juelich.de/en/news/effzett/2024/fresh-opportunity-for-the-sodium2013sulfur-battery