In addition to the chemical reactivity issue, most metal oxides have poor ionic conductivity for both cations and anions. Therefore, as the discharge products build up in a solid oxide metal air battery (as shown in Figure ), there will likely be passivation of the oxide-ion solid electrolyte. In order to solve this issue, and the chemical stability problem, a more complex scheme is required. Naively, the addition of a molten salt between the liquid metal and the anion solid electrolyte could solve both of these issues: the salt prevents contact between the liquid metal and the oxide-ion solid electrolyte, and also provides some solubility to the metal oxide discharge products to dislodge them from the interface. However, molten metals are often slightly soluble in molten salts , which means that the salt will not be able to protect the oxide-ion electrolyte from reactions with the molten metal. To prevent the dissolution of molten metal, an additional solid electrolyte is placed in between the metal and molten salt. This is shown schematically in Figure .