Safe, cheap, fast charging: Na-S solid-state battery becomes tangible

Batteries with sodium and sulfur promise to be cheaper to produce because both elements are readily available. Sodium also has a high conductivity, which further increases the performance of the battery.

Solid-state batteries, on the other hand, are considered to be particularly safe and, above all, can be charged much faster than lithium-ion batteries, for example. It is said to be possible to charge the same amount of energy in a solid-state battery about twice as quickly.

Unfortunately, the production and subsequent practical use of such a battery is still associated with major difficulties.

This is precisely where a research team from the University of Osaka has come in. According to their own statements, they have come up with a manufacturing process that is efficient and suitable for industrial production in the future.

The electrolyte made of sodium and sulfur can be combined with other elements to further improve the electrical properties and durability. In addition, it was possible to produce the electrolyte at normal pressure and comparatively low temperatures of 700 °C (1,300 °F).

In the tests with the energy cells, a practicable 1.2 to 2.4 volts were measured at room temperature. The energy density is also close to the range that current rechargeable batteries can offer.

The measured ion conductivity in some tests also reached values that are already considered super ion conductors. Here too, of course, at room temperature. Tungsten and antimony were added to the solid electrolyte to achieve 125 millisiemens per centimeter. This outperforms a normal ion crystal by a factor of a billion, and normal battery acid by a factor of ten. At the same time, the researchers were able to achieve 300 charges in their battery cell, with 75 percent remaining capacity.

Good electrical properties, production at moderate temperatures, inexpensive starting materials and a solid electrolyte for safe handling and, above all, high charging and discharging currents. It will be interesting to see what further progress will be made in the field of sodium solid-state batteries.