The cell design is similar to that published in 1987 by Semkow . However, in order to enable the use of a lithium metal negative electrode, we used a tube, closed on one end, made of Li6.4La2.8Al0.2Zr1.4Ta0.6O12 (LLZO) in order to contain the molten lithium at high temperatures. A stainless-steel wire was used for the current collector to the molten lithium. The cell utilized an equimolar LiCl-KCl molten salt (Sigma) to provide sufficient oxide and lithium-ion transport and act as a solvent for the discharge products. An oxide solid electrolyte was used to both provide the housing for the cell, and also transport oxide ions from the positive electrode to the molten salt. The oxide solid electrolyte was made of ZrO2 with 8% Y2O3 (YSZ, McDanel Ceramics). The YSZ tube is 0.95 cm outside diameter, and 0.64 cm inside diameter. The positive electrode was made of porous Pt (Heraeus) and a silver wire was adhered to the platinum to establish an electrical connection. The porous Pt was coated on a surface area of about 10 cm 2 . YSZ tube was connected to a Swagelok ultra-torr fitting to allow for argon gas to be applied to the cell, preventing oxidation of the lithium. A schematic of the cell is shown in Figure .