Researchers from Sandia National Laboratories have designed a new kind of grid-scale molten sodium batteries which can be used at lower temperatures than conventional battery types. The novel battery types can also use lower cost materials than conventional ones.
Molten sodium batteries are used to store energy from renewable sources such as solar panels and wind turbines, and have been used commercially for many years now. However, traditional forms of these batteries operate at 520-660 degrees Fahrenheit, while Sandia’s new design operates at 230 degrees Fahrenheit instead – allowing significant savings in both cost and energy.
The new design was published today in the scientific journal Cell Reports Physical Science.
“We’ve been working to bring the operating temperature of molten sodium batteries down as low as physically possible,” said Leo Small, the project’s lead researcher. “There’s a whole cascading cost savings that comes along with lowering the battery temperature. You can use less expensive materials. The batteries need less insulation and the wiring that connects all the batteries can be a lot thinner.”
A smaller version of Sandia’s battery was tested for eight months, with the battery charged and discharged more than 400 times over this period to test its efficacy.
At 3.6 volts, Sandia’s sodium-iodide battery has a 40% higher operating voltage than commercial molten sodium batteries. A higher voltage means it has a higher energy density, with Small adding that this means future versions of the battery would need fewer cells, fewer connections between cells and an overall lower unit cost to store the same amount of electricity.
The project’s next step is to continue streamlining the technology and improve efficiency to get the battery to charge and discharge faster. The team has estimated the product may take a further five to 10 years to hit commercial markets, though this time frame is largely due to commercialisation challenges rather than technical ones.
Development of Sandia’s new sodium battery was supported by the Department of Energy’s Office of Electricity Energy Storage Program.
