Discharge performance of solid-state oxygen shuttle metal-air battery using Ca-stabilized ZrO₂ electrolyte

The effects of metal choice on the electrochemical performance of oxygen-shuttle metal-air batteries with Ca-stabilized ZrO₂ (CSZ) as the electrolyte and various metals as the anodes were studied at 1073 K. The equilibrium oxygen partial pressure (P_O2) in the anode chamber was governed by the metal used in the anode chamber. A lower-P_O2 environment in the anode decreased the polarization resistance of the anode. The oxidation of oxide ions to oxygen in the anode is drastically enhanced by the n-type conduction generated in the CSZ electrolyte when it is exposed to a reducing atmosphere. A high discharge potential and high capacity can be achieved in an oxygen-shuttle battery with a Li or Mg anode because of the fast anode reaction compared to that of cells with a Zn, Fe, or Sn anode. However, only the mildly reducing metals (Zn, Si, Fe, and Sn) can potentially be used in rechargeable metal-air batteries because the transport number of the CSZ electrolyte must be unity during charge and discharge. Oxygen shuttle rechargeable batteries with Fe, and Sn electrodes are demonstrated.