Effect of Bi2O3 on the electrochemical performance of LaBaCo2O5+δ cathode for intermediate-temperature solid oxide fuel cells

Abstract The LaBaCo 2 O 5+δ − x wt.% Bi 2 O 3 (LBCO- x Bi 2 O 3 , x =10, 20, 30, and 40) were prepared as composite cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs) via the conventional mechanical mixing method. The effect of Bi 2 O 3 on polarization resistance, overpotential, and long-term stability of the LBCO cathode was investigated. An effective sintering aid for LBCO cathode, Bi 2 O 3 not only lowers its sintering temperature by ~200 °C, but also improves the electrochemical performance within the intermediate temperature range of 600–800 °C. Electrochemical impedance spectroscopy measurements showed that the addition of 20 wt% Bi 2 O 3 to LBCO exhibited the lowest area-specific resistance of 0.020 Ω cm 2 at 800 °C in air, which was about a seventh of that of the LBCO cathode at the same condition. At a current density of 0.2 A cm −2 , the cathodic overpotential of LBCO-20Bi 2 O 3 was about 12.6 mV at 700 °C, while the corresponding value for LBCO was 51.0 mV. Compared to B 2 O 3 –Bi 2 O 3 –PbO frit, the addition of Bi 2 O 3 significantly improved the long-term stability of cathode. Therefore, LBCO-20Bi 2 O 3 can be a promising cathode for IT-SOFCs.