Optimization on fabrication and performance of A-site-deficient La _0.58Sr _0.4Co _0.2Fe _0.8O _3-δ cathode for SOFC

A-site-deficient perovskite cathode material La _0.58Sr _0.4Co _0.2Fe _0.8O _3∈-∈δ (L58SCF) is coated on the yttria-stabilized zirconia electrolyte by screen-printing technique. Several key fabrication parameters including selection of additives (binder and pore former), effect of coating thickness, sintering temperature and time on the microstructure, and electrochemical performance of cathode are investigated by scanning electron microscopy and electrochemical impedance spectroscopy. We study the microstructure and the electrochemical property of the cathode with different kinds of additives. Results show that the cathode possesses fine microstructure, enough porosity, and ideal electrochemical property when polyvinyl butyral serves as both binder and pore former in the cathode. The cathode with three screen-printing coats (thickness 28∈±∈7 μm, weight 6.07∈±∈0.72 mg cm ^-2) sintering at 1,000 °C for 2 h shows lower polarization resistance of 0.183 Ω cm ² at 800 °C. Based on the optimized parameters, the polarization resistances of the L58SCF-Ce _0.8Gd _0.2O _1.9∈-∈δ composite cathode display the R _p values of 0.067 Ω cm ² at 800 °C, 0.106 Ω cm ² at 750 °C, 0.225 Ω cm ² at 700 °C, and 0.550 Ω cm ² at 650 °C.