On the synthesis and performance of flame-made nanoscale La0.6Sr0.4CoO3−δ and its influence on the application as an intermediate temperature solid oxide fuel cell cathode

Abstract: Flame spray synthesis (FSS), a large-scale powder processing technique is used to prepare nanoscale La0.6Sr0.4CoO3−δ powder for solid oxide fuel cell cathodes from water-based nitrate solutions. Influence of processing is investigated on basis of the as-synthesised powders by X-ray powder diffraction (XRD), thermal gravimetric analysis (TGA), nitrogen adsorption (BET) and electron microscopy (SEM and TEM). Against the background of a nanostructured cathode morphology for an intermediate temperature solid oxide fuel cell (IT-SOFC) at 600°C, an optimised and high surface area flame-made La0.6Sr0.4CoO3−δ nanopowder of 29m2 g−1 is used to investigate its performance and chemical reaction with common electrolytes (Y0.16Zr0.84O2−δ , Ce0.9Gd0.1O2−δ and Sc0.20Ce0.01Zr0.79O2−δ ). Secondary phase analysis from XRD measurements revealed a substantially lower La2Zr2O7 and SrZrO3 formation in comparison to conventional spray pyrolysed and submicron powder of about 9m2 g−1. TGA and resistivity measurements proofed that La0.6Sr0.4CoO3−δ is non-sensitive towards carbonate formation under CO2 containing atmospheres. Electronic bulk conductivity of 2680Scm−1 (600°C) and 3340Scm−1 (500°C) were measured in air and as function of oxygen partial pressure (2×105 Pa> p(O2)>1.2×10−2 Pa) in the temperature range between 400 and 900°C. Electrochemical performance is determined by impedance spectroscopy on symmetrical cells of screen printed nanoscale La0.6Sr0.4CoO3−δ on Ce0.9Gd0.1O2−δ substrates from which an area specific resistance (ASR) of 0.96Ωcm2 at 600°C and 0.14Ωcm2 at 700°C were obtained. [Copyright &y& Elsevier]