New Potential Candidates for Redox Battery Using Liquid Ammoniates: Na+/Na and Ag+/Ag

Abstract

Liquid ammoniates, which are highly conductive electrolyte (more than 100 mS.cm-1 at 20 °C), are proposed as solvents for a redox battery working around room temperature, and up 80 °C. In the neg. compartment, the anolyte is NaI • 3.3NH3, and the Na+/Na couple is proposed. It is reversible, as determined by cyclic voltammetry and galvanostatic cycling. In the pos. compartment, the catholyte NaI • 3.3NH3 enriched in silver cations is proposed too. The cathodic material is merely this compound and the cathode is the silver metal. The couple Ag+/Ag is reversible too, as determined by cyclic voltammetry and galvanostatic cycling. Metallic sodium is extremely stable in this electrolyte; therefore NaI • 3.3NH3 could be used in a redox battery of high energy d. and high power d. The maximum working temperature, which is proposed, 70 °C, is lower than the m.p. of sodium (98 °C), and avoids high pressures of ammonia.