ELECTROCHEMICAL CHARACTERIZATION AND MECHANISMS OF SOLID OXIDE FUEL CELLS BY ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY UNDER DIFFERENT APPLIED VOLTAGES

摘要

In this paper, the behavior of an anode-supported solid oxide fiiel cell is studied by using voltage-current density measurement and electrochemical impedance spectroscopy. The cell total polarization obtained from electrochemical impedance spectroscopy results is shown to be consistent with the area-specific resistance calculated from the voltage-current density curve. An electrolyte-supported solid oxide fuel cell is then used to build an equivalent electrical circuit model using reference electrodes and electrochemical impedance spectroscopy. A four-constant phase element model is proposed to analyze the anode-supported solid oxide fuel cell. The model is used to evaluate an anode-supported solid oxide fuel cell under different cell voltages. The individual resistances are also studied as a function of applied voltage, and their physical meaning is explained in terms of reaction mechanisms occurring at the cathode and anode. It is shown that some of the obtained resistances are independent of diffusion while others have both a charge transfer and diffusion component.