Abstract
Room temperature molten salts consisting of 1‐methyl‐3‐ethylimidazolium chloride (MEIC) and aluminum chloride
have been examined as possible electrolytes for a room temperature design of the sodium/iron(II) chloride battery. This work examines the conditions required to achieve efficient reduction and oxidation of sodium from a sodium chloride buffered, neutral melt. Two substrates were examined, tungsten and 303 stainless steel, using both cyclic voltammetry and chronopotentiometry. Melts were protonated using a closed electrochemical cell to allow quantification of the effect of dissolved 
on the efficiency of the sodium couple. A threshold of approximately 6 Torr 
partial pressure was observed for sodium plating‐stripping. Below this threshold, the sodium couple was not observed. The results show that the sodium plating‐stripping efficiency increases with increasing current density; however, the efficiency reaches a maximum and is adversely affected by high overpotentials and extended exposure of the sodium to the melt. It appears that some passivation occurs as even a very thin layer of plated sodium exhibits a steady open‐circuit voltage over long periods in the melt.