Electrochemical behavior of composite cathodes in contact with solid electrolyte La10Ge6O27

The cathodic overvoltage of composite cathodes 50 wt % La0.8Sr0.2MnO3 (LSM) + 50 wt % La10Ge6O27 (LGO) (further on, LSM-LGO), LSM-SSZ (Zr0.835Sc0.165O2−δ), Ag-Pd-LGO, and Ag-Pd-SSZ in contact with the LGO electrolyte is measured. The temperature dependences of the polarization conductivity and the working-current densities of the same composite cathodes are investigated. The study is performed at 700–900°C. A comparison with the SSZ electrolyte is conducted. The chemical interaction in the LSM-LGO composition is studied. It is demonstrated that the interaction of lanthanum-strontium manganite with lanthanum germanate occurs with the dissolution of the initial phases in one another and with the formation of fresh phases at elevated temperatures. Coefficients of linear thermal expansion of the LGO and SSZ electrolytes and the LSM, LSM-LGO, and LSM-SSZ electrode materials are compared at 40–900°C. Most of the studied electrodes in contact with the LGO electrolyte demonstrate thermomechanical stability and high electrochemical activity.