When we look at ways to efficiently store energy from wind and solar sources, lithium-based batteries are expensive and world-wide geological resources of lithium are actually quite limited. A sodium-based battery, on the other hand, has the potential to store larger amounts of electrical energy at a significantly lower cost. And, nearly all countries have access to large amounts of sodium.

—Steve Martin

Martin says that sodium batteries today use liquid sodium metal that is very dangerous, difficult and expensive to handle. Shifting the operating temperature down to room temperature allows for a longer lasting and considerably safer battery. The lower operating temperature should also result in a 20 percent improvement in energy density over state-of-the-art lithium-ion cells.

Martin’s new battery will use a solid anode, cathode and electrolyte separator. This construction will eliminate all of the flammable and reactive materials from the battery and make it safer.

Martin’s group at Iowa State will develop the new solid electrolyte separator; Martin has been exploring new glass compositions with very high ionic conductivities for some time.

A team led by Yan Yao at the University of Houston will create a new cathode for the battery. A team led by Sehee Lee at the University of Colorado Boulder will develop the new anode for the battery. Scott Beckman and Soumik Banerjee at Washington State University will lead a team using theoretical modeling techniques to optimize the construction and operation of the assembled battery. And Solid Power, led by Dr. Josh Buettner-Garrett, will oversee the commercialization of the completed battery.

While this design has been known for a long time, Martin said it has yet to make it to the marketplace. One of the critical problems that has that has kept this new type of battery on the drawing board for so long has been the slow rate at which the solid separator can transport Na⁺ ions across the battery, he said.