Anodic Concentration Polarization in SOFCs
Concentration polarization is important because it determines the maximum power output of a solid oxide fuel cell (SOFC) at high fuel utilization. Anodic concentration polarization occurs when the demand for reactants exceeds the capacity of the porous ceramic anode to supply them by gas diffusion mechanisms. High tortuosities (bulk diffusion resistances) are often assumed to explain this behavior. However, recent experiments show that anodic concentration polarization originates in the immediate vicinity of the reactive triple phase boundary (TPB) sites near the anode/electrolyte interface. A model is proposed to describe how concentration polarization is controlled by two localized phenomena: competitive adsorption of reactants in areas adjacent to the reactive TPB sites, followed by relatively slow surface diffusion to the reactive sites. Results suggest that future SOFC design improvements should focus on optimization of the reactive area, adsorption, and surface diffusion at the anode/electrolyte interface.
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- Resource Relation:
- Conference: Solid State Ionic Devices III: Proceedings of the International Symposium, 2002-26(101-112; Electrochemical Society, Inc.,Pennington,,United States.
- Research Org:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
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- Country of Publication:
- United States
- 30 DIRECT ENERGY CONVERSION corrected conf title, vol, pub name, 03/26/2004 - mfl