Development of La0.6Sr0.4Co0.2Fe0.8O3−δ cathode with an improved stability via La0.8Sr0.2MnO3-film impregnation

Uniform, dense and continuous coatings of La0.8Sr0.2MnO3−δ (LSM) have been successfully deposited on dense/porous La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) substrates via a one-step drop-coating process using a water-based solution in order to improve the operating stability of solid oxide fuel cell cathode. The processing conditions were optimized by precise control of the composition of infiltrating solution, including chelating agents (glycine, citric acid and ethylene glycol), surfactants (polyvinyl alcohol (PVA), polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP)) and pH values (5.25, 4.29, 3.01 and 2.09). Ethanol was found to improve the wetting ability of the water-based solution significantly, but unfortunately causing precipitation. The symmetrical and full cells tests demonstrated that both performance and stability of LSCF cathode can be enhanced by surface modification with an optimized LSM film coating, leading to ∼31% reduction in cathodic polarization resistance and ∼45% improvement in power density (without observable degradation) for almost 350 h operation at 750 °C under a constant voltage of 0.7 V.

► A uniform film without nano-particles has been deposited onto porous backbone.
► Leading to 31% reduction in cathodic polarization resistance by film modification.
► Leading to ∼45% and ∼20% improvement in power density and stability (350 h).
►  Study the effects of chelating agents, surfactants and pH values on film quality.
► Ethanol can improve wetting ability of aqueous solution but causing precipitation.