Zoned Composite Oxide Cathode for Solid Oxide Fuel Cell Durability
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Solution Overview
Problem
Fuel cell output is reduced due to microscopic structural changes in the cathode, particularly in regions with high current density, affecting durability.
Innovation Solution
A fuel cell design incorporating a cathode with a perovskite composite oxide as the main component and a compound containing S and Cr as a secondary component, featuring distinct surface regions with varying occupied surface area ratios of these components to manage current density and prevent excessive structural changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform cathode structure is used, then the manufacturing process is simple, but the current density distribution is uneven causing microscopic structural changes and reduced durability
Solution Approach 1:
The cathode structure is designed with spatially varying composition: the first region (upstream) contains perovskite composite oxide as main component with secondary component compounds, while the second region (downstream) contains primarily perovskite composite oxide. This local quality variation equalizes current density distribution across the cathode surface, preventing microscopic structural changes in high-current-density regions and improving overall durability without requiring complex external control systems.
2Reliability
If the secondary phase content is increased uniformly across the cathode, then current density is reduced, but the cathode performance and power output decrease
Solution Approach 1:
The cathode is segmented into functionally distinct regions: the first region (upstream) contains secondary component compounds to reduce local current density and prevent structural degradation, while the second region (downstream) maintains high perovskite composite oxide content to preserve electrochemical performance and power output. This segmentation allows the cathode to simultaneously achieve durability in high-stress regions and high performance in low-stress regions.
Data Source
AI summary
A fuel cell comprises an anode, a cathode, and a solid electrolyte layer. The cathode contains a perovskite composite oxide as a main component and contains a compound that includes at least one of S and Cr as a secondary component. The cathode has a surface on the opposite side to the solid electrolyte layer. The surface of the cathode includes a first region and a second region that is positioned downstream of the first region in relation to the direction of oxidant gas flow in which the oxidant gas flows over the surface. The first region and the second region respectively contain a main phase configured by a perovskite composite oxide and a secondary phase that is configured by the compound. The occupied surface area ratio of the secondary phase in the first region is greater than the occupied surface area ratio of the secondary phase in the second region.