Electrochemical properties of the Ag+|Ag and other reference electrodes in the LiCl–KCl eutectic melts

Thermochemical properties of the Ag+|Ag reference electrode were investigated by comparison with those of the Cl−|Cl2 reference electrode in the LiCl–KCl eutectic melt at 673–873 K, and the influence of the AgCl concentration on the equilibrium potential was also studied. The potential difference between the Ag+|Ag electrode and the Cl−|Cl2 reference electrode varied in nearly linear proportion to the concentration of AgCl ranging from 0.01 to 20 mol%. When the AgCl concentration in the inner solution of the Ag+|Ag electrode was 1.02 mol%, the equilibrium potential, E, of the Ag+|Ag electrode versus the Cl−|Cl2 reference electrode at 673–873 K is described as following: E = −1.061 (±0.005) + 0.0000649 (±0.0000010)T, where T   is the temperature in K. Since the density increased with an increase of the AgCl content, the mole number of electrolytes in a given volume increased. Accordingly, the standard redox potential, EAg+|Ag0, could be corrected by the equation: EAg+|Ag0=−1.080(±0.005)+0.000346(±0.000005)T. Furthermore, characteristics of other reference electrodes such as the Al3+|Al and Li+|Li (Li–Al and Li–Sb alloys) electrodes were investigated. The standard redox potential, EAl3+|Al0, of the Al3+|Al couple at 673–873 K is described as following: EAl3+|Al0=−2.289(±0.005)+0.000405(±0.000005)T. The equilibrium potential between the Li–Al (Li:Al = 42:58 in mol%) and the Cl−|Cl2 reference electrode, ELi+|Li(Li–Al)ELi+|Li(Li–Al) and that between the Li–Sb (Li:Sb = 59:41 in mol%) alloys electrode and the Cl−|Cl2 reference electrode, ELi+|Li(Li–Sb)ELi+|Li(Li–Sb), were obtained at the temperature range from 673 to 873 K (ELi+|Li(Li–Al)=−3.923(±0.005)+0.000860(±0.000005)T and ELi+|Li(Li–Sb)=−2.960(±0.005)+0.000313(±0.000005)T(ELi+|Li(Li–Al)=−3.923(±0.005)+0.000860(±0.000005)T and ELi+|Li(Li–Sb)=−2.960(±0.005)+0.000313(±0.000005)T.