Electrode-Electrolyte Compatibility in Solid-Oxide Fuel Cells: Investigation of the LSM-LNC Interface with X-ray Microspectroscopy

Solid-oxide fuel cells (SOFC) are at the forefront of energy materials research, representing the most efficient way to convert a wide range of fuels to electrical energy. Research efforts have been primarily directed at the development and characterization of new materials, as reported in a number of recent reviews on these topics. The structural and chemical compatibility between electrodes and electrolytes is a critical issue: the materials should display similar thermal expansion coefficients, and most importantly, they should minimize the interdiffusion of chemical species at the interface. The formation of insulating phases due to cation diffusion is usually investigated by means of X-ray diffraction (XRD) to detect the growth of crystalline phases in powder mixtures treated at high temperatures.6-10 From a microchemical point of view, the information on the extent of cation interdiffusion is obtained with scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS) on cross sections of the electrode-electrolyte assembly.11 In some cases, electron microspectroscopy has also been used to elucidate the mechanisms of interdiffusion and the oxidation state of cations at the phase boundary between LSM/YSZ, LSCF/GDC, and NiO/GDC.