Electrodes and Electrolytes for Molten Salt Batteries: Expanding the Temperature Regimes

Abstract

Molten salts have been employed in energy storage and generation technologies for numerous applications. Examples include thermal and rechargeable batteries employing LiCl-KCl and NaCl-AlCl3 electrolytes, molten carbonate fuel cells, and thermal energy storage using molten nitrates. For electrochemical applications, molten salt electrolytes offer many benefits over conventional aqueous and organic electrolytes including minimal vapor pressure, wide electrochemical window, inherently high ion concentration, and low to minimal toxicity. Additionally, the high temperature operation of molten salt electrolytes is attractive for fast kinetics and high power requirements (and is required for thermally activated batteries and for thermal energy storage); however, it also poses materials difficulties in some instances. Room temperature molten salts, also termed ionic liquids, retain many of the benefits of high temperature electrolytes, but without the thermal handling problems.