Developing Batteries Worth Their Salt: Technical Advances for Cost Effective Molten Sodium Batteries

E.D. Spoerke, A. Maraschky, M. Meyerson, A. Peretti, S. Percival, L. Small
Sandia National Laboratories,
United States

Keywords: sodium battery, molten salt, grid-scale storage


Safe, cost-effective, reliable batteries for grid-scale and long-duration storage remain an elusive, but critical need in the world’s evolving and expanding electrical infrastructure. Here, we describe a promising high voltage, low temperature molten sodium-halide battery that operates near 100 degrees Celsius, a dramatic reduction from the ~300 degrees Celsius operating temperatures common to traditional molten sodium batteries. This low temperature operation promises reduced system costs and improved material lifetimes, taking advantage of a highly conductive, engineered NaSICON-based separator, a molten sodium anode, and an essential low melting-temperature inorganic sodium iodide (NaI)-based catholyte. Lab-scale testing has revealed high battery voltages (>3V) and stable cycling for months at a time, but pushing this battery toward lower cost and higher performance introduces challenges ranging from molten salt catholyte chemistry to solid state separator performance and charge transfer at critical solid-liquid interfaces. Successful innovation and improved engineering designs aimed at overcoming these challenges, however, offer promise that these batteries may soon be suitable for reliable, large-scale, long-duration battery storage. 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-NA0003525.