Highly active and novel A-site deficient symmetric electrode material (Sr_0.3La_0.7)_1−x (Fe_0.7Ti_0.3)_0.9Ni_0.1O_3−δ and its effect on electrochemical performance of SOFCs

A-site deficient (Sr_0.3La_0.7)_1-x (Fe_0.7Ti_0.3)_0.9Ni_0.1O_3-δ ((SL)_1-xFTN) symmetrical electrodes with compositions x = 0.1, 0.2 and 0.3 denoted as SLFTN-01, SLFTN-02, and SLFTN-03 respectively were synthesized via modified Pechini method. The as prepared samples were further coated on LGSM electrolyte through screen-printing technique. Electrochemical performance was significantly improved for A-site deficient (SL)_1-xFTN due to increased concentration of oxygen vacancy. XRD patterns revealed better reversibility for (SL)_1-xFTN with rhombohedral structure. Low polarization resistance (Rp) ~0.210, 0.195 and 0.165 Ωcm² (in dry H₂) and 0.069, 0.046 and 0.043 Ωcm² (in air) was measured for SLFTN-01, SLFTN-02, and SLFTN-03 respectively at a temperature of 750 °C. Highest conductivities ~326, 338 and 342 Scm⁻¹ were calculated in air and the conductivities obtained in dry H₂ were ~0.64, 0.81 and 1.01 Scm⁻¹ at 700 °C. It was observed that small polaron mechanism was responsible for the decreased conductivity with the increased temperature range. The fabricated symmetrical cell ((SL)_1-xFTN/LDC|LSGM|LDC/(SL)_1-xFTN), maintained good stability without any degradation during the test time ~500 h (in air) and 100 h (in dry H₂). The detailed investigations categorized the fabricated cells well suited as anode and cathode with improved performance and excellent stability both in oxidizing and reducing atmospheres.