Cell performance, impedance, and various resistances measurements of an anode-supported button cell using a new pressurized solid oxide fuel cell rig at 1-5 atm and 750-850 °C

We report a novel pressurized solid oxide fuel cell (SOFC) rig that overcomes the stagnation flow problem in classic button cell setups, allowing fuel and air to distribute uniformly over anode and cathode surfaces. Power and impedance measurements of an anode-supported full button cell (ASC; NiO-YSZ/YSZ/LSM-GDC-LSM) operated at p = 1-5 atm and T = 750-850 °C show that both pressurization and increasing temperature enhance the cell performance, which are explained by the Nyquist plots consisted of a high frequency arc with characteristic frequencies (fc) around 100-1000 Hz relating to the cathode activation overvoltage and a low frequency arc with fc around 10-30 Hz corresponding to the anode concentration overvoltage. The activation overvoltage decreases with increasing p and/or T, while the concentration overvoltage decreases with increasing p but rather insensitive to T. We find that the activation overvoltage is the major source for the polarization resistances contributing 63%-82% depending on pressure, temperature, and current density, while the concentration overvoltage is a minor one contributing 18%-37% for the present ASC. These results and the rig should be useful for our understanding and further studies of pressurized SOFCs.