K2NiF4 type La2 − xSrxCo0.8Ni0.2O4 + δ as the cathodes for solid oxide fuel cells

K2NiF4 structured La2Co0.8Ni0.2O4 + δ is an oxygen overstoichiometric oxide with high oxygen diffusion and oxygen surface exchange coefficients at temperature range 450–800 °C. In this work, composites consisting of La2 − xSrxCo0.8Ni0.2O4 + δ (LSCN, x = 0, 0.4, 0.8, 1.2, 1.6) and Ce0.9Gd0.1O1.95 (GDC) have been investigated as the cathodes for low-and-intermediate temperature solid oxide fuel cells (SOFCs). AC impedance spectroscopy on symmetric cells indicated that among the series of LSCN–GDC composites, La1.2Sr0.8Co0.8Ni0.2O4 + δ-based electrode had the lowest interfacial polarization resistance, which was 1.36 Ω cm2 at 600 °C when the electrode was not activated. Significant activation effect was observed with a single cell when current treatment was performed at 200 mA cm− 2 within 30 min. The single cell with La1.2Sr0.8Co0.8Ni0.2O4 + δ–GDC as the cathode generated power density up to 350 mW cm− 2 at 600 °C. In addition, the performance was pretty stable when a constant output voltage of 0.5 V was set for 36 h. These results suggest that La2 − xSrxCo0.8Ni0.2O4 + δ could be promising materials as the cathodes for SOFCs that operated at low-and-intermediate temperatures.