Electrochemical characterization of La_0.8Sr_0.2MnO₃-coated NiO as cathodes for molten carbonate fuel cells

Abstract

La_0.8Sr_0.2MnO₃ was coated on porous NiO cathode using a simple combustion process. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed in the cathode characterizations. The electrochemical behavior of La_0.8Sr_0.2MnO₃-coated NiO cathodes (LSM–NiO) were also evaluated in a molten 62 mol%Li₂CO₃+38 mol%K₂CO₃ eutectic at 650 °C under the standard cathode gas condition by electrochemical impedance spectroscopy (EIS). The impedance response of the NiO and LSM–NiO cathode at different immersion times is characterized by the presence of depressed semicircles in the high frequency range and an extension at low frequencies. Impedance analysis showed that the behavior of the developed cathode was similar to that of the conventional nickel oxide cathode. The LSM–NiO showed a lower dissolution and a better catalytic efficiency superior to the state-of-the-art NiO value. Thus the cathode prepared with coating method to coat La_0.8Sr_0.2MnO₃ on the surface of NiO cathode is able to reduce the solubility of NiO to lengthen the lifetime of MCFC while maintaining the advantages of NiO cathode. The LSM–NiO shows promise as an alternate cathode in molten carbonate fuel cells (MCFCs).