Emf Measurements of Electrochemically Prepared Lithium-Aluminum Alloy

The open‐circuit voltages of the cell were measured over the composition range of 6.9–50 a/o (atom per cent) alloy in the temperature range 282°–389°C. The composition of the alloy was varied by coulometrically charging and discharging the cell. The emf values of the cell are independent of the composition up to 47 a/o lithium in the alloy and their temperature dependence follows the relationship , where is in millivolts, , and σ is the standard deviation. The constant potential exhibited by the alloy is ascribed to the formation of phase on the alloy surface. The standard free energies of formation for are estimated to be −7.49, −7.24, and − 7.09 kcal/mole at 300°, 350°, and 380°C, respectively. The standard enthalpy and entropy of formation are constant, −10.40 kcal/mole and −5.08 cal/mole · deg, respectively, in this temperature range. Since the electrochemically prepared lithium‐aluminum alloy has a constant potential over a wide composition range and exhibits good electrochemical behavior, it can serve as a good reference electrode as well as a high energy density anode in molten salt systems containing lithium.