Effects of pressurization and temperature on power generating characteristics and impedances of anode-supported and electrolyte-supported planar solid oxide fuel cells

Power generating characteristics of pressurized anode-supported cell (ASC) and electrolyte-supported cell (ESC) are measured using the same single-cell stack setup, a planar full cell sandwiched by a pair of rib-channel flow distributors. Both ASC and ESC apply the same flow rates (Q_anode = 0.5 slpm H₂ + 0.4 slpm N₂ and Q_cathode = 0.9 slpm air) measured at three operating temperatures (T = 750°C, 800°C, 850°C), each T under five pressures (p = 1, 2, 3, 4, 5 atm), having a total of 30 data sets for comparison. It is found that under loaded conditions, ASC has much larger increments in power densities, about three folds higher, than ESC due to pressurization. As T increases from 750°C to 850°C at 0.7 V, power densities of ASC/ESC increase from 175/97 mW cm^-2 to 309/193 mW cm^-2 at p = 1 atm, while at p = 5 atm, the increases of power densities are 281/137 mW cm^-2 to 476/250 mW cm^-2, showing a stronger temperature dependence than pressurization. Corresponding electrochemical impedance spectra show that the better cell performance of ASC is attributed to both lower ohmic and polarization resistances found in ASC than that in ESC.