Evaluation of La_xSr_2-xFeO₄ layered perovskite as potential electrode materials for symmetrical solid oxide fuel cells

This paper presents layered perovskite La_xSr_2-xFeO₄ electrodes with La_0.9Sr_0.1Ga_0.8Mg_0.2O_3-δ (LSGM) electrolyte for symmetrical solid oxide fuel cells. XRD and TGA results reveal a good stability of La_0.8Sr_1.2FeO₄ electrode in reducing atmosphere. An excellent chemical compatibility in air and 5% H₂/Ar was found between La_0.8Sr_1.2FeO₄ electrode and LSGM electrolyte. In air, the maximum conductivity of these materials occurred as x = 0.6, however, La_0.8Sr_1.2FeO₄ sample has the highest conductivity in 5% H₂/Ar. The electrochemical properties were evaluated by impedance spectroscopy and current-voltage curves. At 800 ^°C, the polarization resistance of the La_0.8Sr_1.2FeO₄ cathode is about 1.85 Ω cm² in air, while the polarization resistance of the La_0.8Sr_1.2FeO₄ anode is about 5.82 Ω cm² under 5% H₂/Ar. A single cell (1.0 cm² active area) was fabricated with 70wt% La_0.8Sr_1.2FeO₄+30wt% LSGM as both cathode and anode, LSGM (1.1 mm thickness) as electrolyte. At 800 ^°C, the maximum power density was 73 mW cm^-2 under humidified H₂ as fuel.