Flame spray synthesis of nano lanthanum strontium manganite for solid oxide fuel cell applications

Abstract

Lanthanum strontium manganite is a classic cathode material for solid oxide fuel cells (SOFC). Nanosized LSM particles, due to their higher specfic surface area, have been found to enhance the electrode performance by providing a larger three phase boundary (TPB) area. However conventional processes like solid state, sol-gel or co-precipitation, produce particles having low specic surface area (< 8 m²/g) and hence require high sintering temperatures. Moreover these processes are multi-step and are hence time consuming. In the present work, single phase LSM with a crystallite size of 26 nm and a specfic surface area as high as 40 m²/g was produced by a flame spray pyrolysis method. The as-synthesized powder was characterized by X-ray diffraction (XRD), nitrogen adsorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Porous thin films were prepared by spin coating a water based dispersion of LSM. Electrochemical performance of the nanoparticulate cathode films were studied using impedance spectroscopy. Interfacial polarization resistance value of as low as 0.085 Ωcm ² at 850°C was obtained by this method. This method thus offers a very cost effective approach for the preparation of highly active cathode thin films for SOFC applications.