Sodium Ion-Conducting Separator Development

Amanda Peretti, Stephen Percival, Leo Small, Babu Chalamala, and Erik D. Spoerke

Sandia National Laboratories

Large scale electrical energy storage is increasingly important in developing a reliable energy grid. Sodium-based batteries may resolve issues of safety, cost-effectiveness, and battery lifetime that plague current grid-scale battery options. A critical part of these new batteries is the solid-state separator that facilitates sodium ion transfer between the anodes and cathodes. We are developing a separator that has high ionic conductivity at the low-to-intermediate temperatures desired for a new class of Na-based batteries. These separators must exhibit mechanical robustness and both chemical and thermal stability against a variety of electrolytes of interest. Here, we discuss separators specifically composed of highly conductive NaSICON (Na Super Ion CONductor) ceramic both as a bulk material and encased in a polymer matrix. NaSICON has been shown to have high Na+ conductivity at temperatures below 200°C, well within our battery operating temperatures, and the surrounding polymer serves as a framework in which to suspend the NaSICON within the battery. The use of this ion-separator is a promising, cost effective solution to an otherwise fragile battery component.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525.