A new design for a grid energy storage battery built with low-cost and abundant sodium and aluminum provides a pathway toward a safer, more sustainable and more scalable stationary energy storage system.

The molten salt battery engineered by researchers from U.S. Pacific Northwest National Laboratory, Ohio-based Nexceris and South Korea’s Research Institute of Industrial Science and Technology has the potential to charge and discharge much faster than other conventional high-temperature sodium batteries. The system also operates at a lower temperature while maintaining excellent energy storage capacity.

A previously demonstrated neutral molten salt reaction is extended and amplified by a further reaction into an acidic molten salt, which serves to increase battery capacity. This acidic reaction mechanism retained 82.8% of peak charge capacity after 345 charge/discharge cycles at high current.

Equipped with a solid-state, sodium-based electrolyte, the flat, scalable battery modules can more easily be stacked and expanded relative to conventional tubular shapes. The flat cell design allows cell capacity to be increased by simply using a thicker cathode, which the researchers leveraged to demonstrate a triple capacity cell with sustained discharge of 28.2 hours under laboratory conditions.

The new nickel-free design is expected to prove of value in short- to medium-term grid energy storage over 12 to 24 hours. The low-cost, grid-scale storage technology described in Energy Storage Materials could enable wind, solar and other intermittent renewables to contribute to power grids.