Electrode behaviour at (La,Sr)MnO 3/Y 2O 3–ZrO 2 interface by electrochemical impedance spectroscopy

Abstract

The electrode behaviour of strontium (Sr)-doped LaMnO 3 (LSM) electrodes is investigated by an electrochemical impedance spectroscopy technique over the temperature range 850–1000 °C and the oxygen partial pressure range 0.01–0.21 atm. The electrodes are screen-printed on 50 mm×50 mm 3 mol% Y 2O 3–ZrO 2 electrolyte cells with an electrode surface area of 10 cm 2. The impedance responses show two separable arcs and are analysed in terms of two different equivalent circuits with comparable information on the electrode processes at high and low frequencies. The electrode process associated with the high-frequency arc is essentially independent of O 2 partial pressure with an activation energy of ∼74 kJ mol −1, while that at the low-frequency arc has an activation energy of ∼202 kJ mol −1 and a reaction order with respect to O 2 partial pressure of ∼0.5 at low temperatures and ∼0.85 at high temperatures. The electrode processes associated with the low- and high-frequency arcs are discussed.