The new electrode made of a liquid metal alloy allows sodium-beta batteries to last longer and help streamline their manufacturing method as well as reduce the risk of accidental fire.
PNNL material scientist Xiaochuan Lu said: "Running at lower temperatures can make a big difference for sodium-beta batteries and may enable batteries to store more renewable energy and strengthen the power grid."
According to Dupont Energy Consulting, over 300MW of large, cargo container-sized sodium-beta batteries are running in the US, Japan and Europe which store electricity generated by rows of solar panels and wind turbines.
PNNL said their broader use has been limited as they operate at high temperatures, which reaches up to 350 degrees Celsius reducing their operating lifespan.
According to PNNL, reducing the battery’s operating temperature creates several other technical challenges.
Lu and his colleagues took an entirely different approach to the wettability problem – modifying the negative electrode.
Researchers experimented with sodium alloys, or sodium blended with other metals instead of using pure sodium.
The team identified a liquid sodium-cesium alloy spreads out well on the beta alumina membrane.
Researchers said a test battery with the new electrode worked well at 150 degrees — with a power capacity of 420 milliampere-hours per gram, matching the capacity of the traditional design.
The research team is now building a larger electrode to test with a larger battery to bring the technology closer to the scale required to store renewable energy.
Image: PNNL materials scientist Xiaochuan Lu assembles a sodium-beta battery in a glove box. Photo: Courtesy of Pacific Northwest National Laboratory.
