Rechargeable Oxide Ion Batteries Based on Mixed Conducting Oxide Electrodes

Abstract

Mixed conducting oxides are frequently studied as electrode materials for solid oxide fuel or electrolysis cells. However, in principle their ability to change stoichiometry depending on the oxygen chemical potential also enables charge storage typical for battery electrodes: Formally neutral oxygen can be incorporated by annihilating oxygen vacancies and creating electron holes, similar to the incorporation of lithium in lithium ion battery electrodes. Electrodes with different reducibility should thus allow operation of an oxide ion battery. This is exemplified for perovskite-type La0.6Sr0.4FeO3−δ (LSF), La0.5Sr0.5Cr0.2Mn0.8O3−δ (LSCrMn), and La0.9Sr0.1CrO3−δ (LSCr) electrodes with blocked oxygen surface exchange. Cells with thin film electrodes are prepared by pulsed laser deposition on yttria stabilized zirconia electrolytes. Charge/discharge cycles and impedance measurements are performed on half cells between 350 and 500 °C and related to the materials defect chemistry. Electrode capacities of up to 350 mA h cm−3 and <0.25 % capacity loss over 19 cycles are measured at potentials between 0.2 and −1.1 V versus O2 at 1 bar. Full cells with LSF cathodes and LSCrMn anodes are successfully operated at 350 to 400 °C with electrode related energy densities up to 70 mW h cm−3, coulomb efficiencies >99 % and good cycling performance. This novel type of rechargeable battery may open further application fields such as elevated temperatures (>200 °C), where common cation-based cells are not applicable so far.