Analytical investigations of varying cross section microstructures on charge transfer in solid oxide fuel cell electrodes

• Published in: Journal of power sources Vol. 196; no. 10; pp. 4695 - 4704
• Main Authors: Nelson, George J., Peracchio, Aldo A., Chiu, Wilson K.S.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.05.2011; Elsevier
• Subjects: Applied sciences; Cross sections; Design engineering; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Electrode microstructure; Electrodes; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Fuel cells; Heterogeneous functional materials; Mathematical analysis; Mathematical models; Microstructure; Solid oxide fuel cell; Solid oxide fuel cells; Supports; Transport phenomena; Heterogeneous functional materials; Electrode microstructure; Transport phenomena; Solid oxide fuel cell; Variable section; Heterogeneous material; Microstructure; Charge transfer
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2010.12.103

An extended surface modeling concept (electrochemical fin) is applied to charge transport within the SOFC electrode microstructure using an analytical modeling approach analogous to thermal fin analysis. This model is distinct from similar approaches applied to SOFC electrode microstructure in its application of a governing equation that allows for variable cross-section geometry. The model presented is capable of replicating experimentally observed electrode behavior inclusive of sensitivity to microstructural geometry, which stands in contrast to existing models that apply governing equations analogous to a constant cross-section thermal fin equation. Insights learned from this study include: the establishment of a suite of dimensionless parameters and performance metrics that can be applied to assess electrode microstructure, the definition of microstructure-related transport regimes relevant to electrode design, and correlations that allow performance predictions for electrodes that provide cell structural support. Of particular note, the variable cross-section modeling approach motivates the definition of a sintering quality parameter that quantifies the degree of constriction within the conducting network of the electrode, a phenomenon that exerts influence over electrode polarization. One-dimensional models are presented for electrochemical fins of several cross-sectional geometries with the ultimate goal of developing a general tool that enables the prompt performance evaluation of electrode microstructures. Such a tool would facilitate SOFC microstructural design by focusing more detailed modeling efforts on the most promising microstructures.