In the charged state, the molten lithium metal is contained in the LLZO tube, and the molten salt electrolyte contains a low concentration of oxide ions, as shown in Figure . As the cell discharges, lithium ions move from the negative electrode into the LLZO tube, and then into the molten salt electrolyte, while the electron is discharged around the external circuit. On the positive electrode side, oxygen gas is oxidized from O2 to 2O -2 where the oxide ions reside in the YSZ tube. The oxide ions transport through the YSZ tube and are deposited into the molten salt electrolyte. In low concentrations, the oxide ions are soluble in the molten salt. However, once the solubility limit is reached, the oxide ions combine with lithium ions to form lithium oxide precipitate. In the fully discharged state, solid lithium oxide exists in the molten salt, with no lithium metal inside the LLZO tube. The lithium and oxide ion transport are outlined in Table and Figure , showing the different electrochemical reactions occurring at each interface. .