This molten salt battery keeps all its energy in hibernation

American researchers have developed a new molten salt battery that retains its charge when cooled. Thus, it could be used to accumulate excess electricity production during a season to release it later in the year.

The molten salt batteries are of great interest to scientists because they are made with common materials, and can be used on a large scale. They could in particular be connected to the electrical network to compensate for the vagaries of renewable energies. Researchers from Pacific Northwest National Laboratory have developed a new molten salt battery for seasonal use. They published their results in the journal Cell Reports Physical Science.

This new battery is intended to store any excess production, for example solar in summer. Once charged, it is put into hibernation and can restore the stored energy later, for example by winter. The researchers used a anode in aluminum and an cathode in nickelwith a molten salt electrolyte containing sulfur. This type of battery usually contains a separator in ceramicbut the researchers opted for fiberglass, which is more durable and less expensive.

A battery that restores 92% charge after three months of hibernation

Like all molten salt batteries, it must be heated to operate. This requires a temperature of 180°C. Once loaded, the battery is cooled so that the electrolyte solidifies and blocks the movement from ions. It is then enough to heat it again to be able to recover the stored energy. The tested battery was able to return 92% of its charge after 12 weeks.

The current prototype fits in the hand, but the researchers believe it is possible to significantly increase its size. In theory, the battery has a density of 260 watt hours per kilogram. It is also inexpensive to produce. The materials for the prototype cost $23 per kilowatt-hour, a price the researchers believe can be lowered to $6 by including ironi.e. 15 times less than the lithium ion batteries.