Fabrication and evaluation of the electrochemical performance of the anode-supported solid oxide fuel cell with the composite cathode of La_(0.8)Sr_(0.2)MnO_(3-δ)-Gadolinia-doped ceria oxide/La_(0.8)Sr_(0.2)MnO_(3-δ)

摘要

The anode-supported single cell was constructed with porous Ni-Yittria-stabilized zirconia (YSZ) as the anode substrate, an airtight YSZ as the electrolyte, and a screen-printed La_(0.8)Sr_(0.2)MnO_(3-δ) (LSM)-Gadolinia-doped ceria (GDQ/LSM double-layer cathode. The SEM results show that the YSZ thin film is highly integrated, fully dense with a thickness of 13 μm, and exhibits excellent compatibility between cathode and electrolyte layers. The effects of feed rates of the reactants, temperature, and contact pressure between the current collector and the unit cell were systematically investigated. The results are based on the assumption that the anode contribution to the polarization resistance is negligible. Our analysis showed that the electrochemical reaction is limited by mass transfer control when the airflow rate is decreased to 500 ml min~(-1). The maximum power density is 204.6 mW cm~(-2) at 800 ℃ with H_2 and air at flow rates of 800 and 2000 ml min~(-1), respectively. According to the AC-impedance data, the resistances of charge transfer at the electrode/electrolyte interface are 3.79 and 1.90 Ω cm~2. The resistances of oxygen-reduction processes are 3.63 and 1.01 Ω cm~2 at 700 and 800 ℃, respectively. The resul ts from the sensitivity analysis of the variation of contact pressure between current collectors and membrane electrode assembly (MEA) show that the influence is enhanced at the regions of the high current density.