Stability of strontium-doped lanthanum manganite cathode in humidified air

The stability of strontium-doped lanthanum manganite (LSM) cathode has been studied using symmetric cells (humidified air, LSM/yttria-stabilized zirconia (YSZ)/LSM, humidified air) under a range of humidification levels (0-50%), temperatures (750-850 [degrees]C), and cathodic biases (0-0.5 V). Electrochemical impedance spectroscopy revealed an increase in non-ohmic resistance with increasing H2O/O sub(2) ratio, temperature, and cathodic bias. Post-test surface and interface studies showed the segregation of SrO particles on the LSM surface and formation of Mn sub(2)O sub(3) and La sub(2)Zr sub(2)O sub(7) compounds at the cathodic LSM/YSZ interface. The increase in non-ohmic resistance is attributed to surface segregation of SrO and interfacial compound formation, whereas formation and growth of SrO at the LSM surface is attributed to water adsorption. La sub(2)Zr sub(2)O sub(7) formation is attributed to interfacial reactions.