All symmetrical metal supported solid oxide fuel cells

Abstract

Metal-supported solid oxide fuel cells (MS-SOFCs) have many advantages like low materials cost, excellent structural stability and high tolerance toward rapid thermal cycling over the traditional all ceramic SOFCs. To facilitate the commercialization of SOFCs, an all symmetrical MS-SOFC with the structure of Ce0.8Sm0.2O2-δ (SDC)-430L anode/Zr0.88Sc0.22Ce0.01O2.12(SSZ) electrolyte/SDC-430L cathode was developed by a tape casting- sintering-infiltration method. When measured in humidified hydrogen fuel and air oxidant, the maximum power densities (MPD) of the fuel cell are 220, 250 and 280 mW/cm2 at 600, 650 and 700℃, respectively. Electrochemical impedance spectra measurement shows that the cell performances are primarily dominated by polarization resistances derived from the SDC-430L electrodes. The pure ohmic resistances are 0.16, 0.21 and 0.29 Ω·cm2 and the polarization resistances are 0.67, 0.90 and 1.22 Ω·cm2 at 700, 650 and 600℃, respectively. Compared with that of the anode, polarization resistance of cathode is much higher. When measured at 650℃, polarization resistances of the symmetrical SDC-430L cell are 0.23 and 1.92 Ω·cm2 in 3%H2O-97%H2 and air, respectively. Further optimizing the cell structure (e. g., applying a finer 430L backbone) and the catalyst materials (e. g., Ag, Pt containing composite materials) may enhance the electrochemical performances of such MS-SOFC.