Analysis of SOFCs Using Reference Electrodes

Abstract

Reference electrodes are frequently applied to isolate the performance of one electrode in a solid oxide fuel cell. However, reference electrode simulations raise doubt to the veracity of data collected using reference electrodes. The simulations predict that the reported performance for the one electrode will frequently contain performance of both electrodes. Nonetheless, recent reports persistently treat data so collected as ideally isolated. This work confirms the predictions of the reference electrode simulations on two SOFC designs, and provides a method of validating the data measured in the 3-electrode configuration. Validation is based on the assumption that a change in gas composition to one electrode does not affect the impedance of the other electrode at open circuit voltage. This assumption is supported by a full physics simulation of the SOFC. Three configurations of reference electrode and cell design are experimentally examined using various gas flows and two temperatures. Impedance data are subjected to deconvolution analysis and equivalent circuit fitting and approximate polarization resistances of the cathode and anode are determined. The results demonstrate that the utility of reference electrodes is limited and often wholly inappropriate. Reported impedances and single electrode polarization values must be scrutinized on this basis.

Examination of the mechanism for the reversible aging behavior at open circuit when changing the operating temperature of (La0.8Sr0.2)0.95MnO3 electrodes

“…The changes in the aging behavior can thus be predicted through pairing the defect chemistry model with an appropriate LSM oxygen reduction model. The authors are currently working toward incorporating the changing defect concentrations into an existing LSM oxygen reduction and corresponding SOFC multiphysics model which can predict the electrochemical performance of a porous LSM electrode similar to the one found in the symmetrical cell samples [39][40][41]. By stepping the defect concentrations in time based upon reasonable cation diffusion coefficients, simulated impedance aging data will be created.…”

Sustainable Energy Application

“…With introducing methane, the R ct increased by 3e4 orders in magnitude, which indicated that the active sites of Ni catalyst was diminished by carbon species deposition on the surface of Ni [192]. From the EIS and CV analysis, the exchange current densities for hydrogen oxidation at GTE Ni-YSZ/YSZ anodes were found to be increased exponentially from ca.…”

Application of silver in microtubular solid oxide fuel cells

“…The contact of silver with an electrolyte may temporarily increase the cell performance because of increase in the three-phase boundary, but the silver deposits may short-circuit the cell. Deposition of silver increased the risk of silver penetration into pinholes in the electrolyte and consequently short-circuit formation [36]. The silver migration was noticed only for the part of the cell near the cell inlet.…”