Conductivity and electrochemical performance of (Ba0.5Sr0.5)0.8La0.2Fe1−xMnxO3−δ cathode prepared by the citrate–EDTA complexing method

This study reports the successful preparation of single-phase perovskite (Ba0.5Sr0.5)0.8La0.2Fe1−xMnxO3−δ (x = 0–0.2) by the citrate–EDTA complexing method. The crystal structure, thermal gravity analysis, coefficient of thermal expansion, electrical conductivity, and electrochemical performance of (Ba0.5Sr0.5)0.8La0.2Fe1−xMnxO3−δ were investigated to determine its suitability as a cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The lattice parameter a of (Ba0.5Sr0.5)0.8La0.2Fe1−xMnxO3−δ decreases as the amount of Mn doping increases. The coefficients of thermal expansion of the samples are in the range of 21.6–25.9 × 10−6 K−1 and show an abnormal expansion at around 400 °C associated with the loss of lattice oxygen. The electrical conductivity of the (Ba0.5Sr0.5)0.8La0.2Fe1−xMnxO3−δ samples decreases as the amount of Mn-doping increases. The electrical conductivity of the samples reaches a maximum value at around 400 °C and then decreases as the temperature increases. The charge transfer resistance, diffusion resistance and total resistance of a (Ba0.5Sr0.5)0.8La0.2Fe0.8Mn0.15O3-δ–Ce0.8Sm0.2O1.9 composite cathode electrode at 800 °C are 0.11 Ω cm2, 0.24 Ω cm2 and 0.35 Ω cm2, respectively.