화학공학소재연구정보센터
Journal of the Electrochemical Society, Vol.142, No.11, 3636-3642, 1995
Stability of Sodium Electrodeposited from a Room-Temperature Chloroaluminate Molten-Salt
Room temperature molten salts consisting of 1-methyl-3-ethylimidazolium chloride (MEIC) and aluminum chloride (AlCl3) 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 HCl on the efficiency of the sodium couple. A threshold of approximately 6 Torr HCl 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.