Growth and structural characterization of lanthanum-strontium-cobalt thin film synthesized by sol-gel dip coating for solid oxide fuel cell

Abstract

The porosity of a solid oxide fuel cell (SOFC) cathode made of lanthanum-strontium-cobalt (LSC) has not been addressed sufficiently. The LSC thin films were deposited on glass substrates by sol-gel dip coating method with different number of layers of film (1 – 4 layers), different annealing temperatures (400 – 600 ºC) at 100 ºC temperature intervals, and different solution temperatures (30 – 60 ºC) at 10 ºC temperature intervals. The dip coating solution was prepared using 40 ml of ethanol, 1 g LSC powder and 0.07 g polyvinyl alcohol (PVA). The structural properties of SOFC cathode were characterized using X-ray diffraction and Fourier transform infrared spectrophotometer. The morphology of SOFC cathode was determined using atomic force microscope and field emission scanning electron microscope. The elemental compositions of LSC films were confirmed using energy dispersive X-ray spectroscopy. The X-ray diffraction results showed that crystalline temperature of LSC was 500 ºC and crystallite size decreased as annealing temperature increased. From the atomic force microscope and field emission scanning electron microscope analysis, the LSC film became smoother as number of layers and annealing temperature increased. Fourier transformed infrared spectrophotometer results showed presence of metal-oxygen bonds at 447 cm-1 and 916 cm-1 which correspond to Co-O, Sr-O, La-O bonding at solution temperature 30 ºC. Hence, it can be concluded that annealing and solution temperature plays vital role in producing high quality LSC thin films.