Dual-Coating Interconnector for SOFC Sealing Integrity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In solid oxide fuel cell (SOFC) and electrolysis cell stacks, the coatings on interconnectors used for oxidation resistance become porous due to reduction reactions with fuel gases, leading to impaired sealing performance, which is not adequately addressed by existing technologies.
Innovation Solution
A dual-coating configuration is employed for the interconnector's surface, where a chromium-containing first coating with high oxidation resistance faces the cathode chamber and oxidizer gas flow channels, and a chromium oxide second coating with higher reduction resistance faces the fuel gas flow channels, preventing exposure of the first coating to the fuel gas and maintaining sealing integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a coating is formed on the interconnector surface for oxidation resistance, then oxidation resistance is improved, but reduction resistance deteriorates due to porosity formation from reduction reactions with fuel gas
Solution Approach 1:
The interconnector surface is divided into multiple regions with different coating configurations: a first surface entirely covered with a protective coating, and a second surface with a coating only in a peripheral region. This segmentation allows each surface to be optimized for its specific functional requirements, resolving the contradiction between oxidation resistance and sealing performance.
Solution Approach 2:
Different coating strategies are applied to different locations on the interconnector. The first surface receives complete coating coverage for maximum oxidation protection, while the second surface has coating only where needed for sealing, leaving other areas exposed. This local differentiation resolves the contradiction by providing oxidation resistance where required while maintaining sealing performance where fuel gas exposure occurs.
2Object-affected harmful factors
If the entire first surface is covered with coating for oxidation resistance, then oxidation resistance is improved, but sealing performance deteriorates due to coating porosity from reduction reactions
Solution Approach 1:
The harmful effect of coating porosity is extracted and isolated by limiting the coated region to only where it is beneficial. The coating is removed from areas where it would contact fuel gas and form pores, while being retained on areas where oxidation protection is needed. This extraction resolves the contradiction by eliminating the source of porosity while preserving oxidation resistance.
Solution Approach 2:
The coating is applied selectively to specific regions rather than uniformly across the entire surface. The peripheral region coating provides localized oxidation protection without exposing large coated areas to fuel gas, thereby preventing widespread porosity formation. This local quality approach resolves the contradiction between oxidation resistance and porosity prevention.
3Object-affected harmful factors
If coating material is selected for oxidation resistance, then oxidation protection is improved, but reduction resistance deteriorates when exposed to fuel gas
Solution Approach 1:
The design proactively prevents the harmful reduction reaction by configuring the interconnector geometry and coating distribution so that the coated surface does not contact fuel gas. This preliminary prevention avoids the stability deterioration that would result from reduction reactions, while still providing oxidation protection where needed.
Solution Approach 2:
The uncoated peripheral region acts as an intermediary barrier that prevents direct contact between the coated oxidation-resistant surface and the fuel gas. This intermediary configuration allows the coating to maintain its compositional stability by eliminating the reduction reaction pathway, while still providing oxidation protection in covered areas.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively prevents the impairment of sealing performance by reducing the exposure of the first coating to fuel gases, thereby enhancing the durability and reliability of the fuel gas flow channel sealing in SOFC and electrolysis cell stacks.
Implementation Method 1
the material used for formation of the coating is selected in consideration of oxidation resistance
Implementation Method 2
the coating may become porous due to reduction reaction between the coating and a fuel gas flowing through the fuel gas flow channel
Data Source
Figure 1
Figure 2
Figure 3
AI summary
To prevent impairment of the sealing performance of a fuel gas flow channel, which would otherwise occur due to reduction reaction between a first coating and a fuel gas. An interconnector-electrochemical reaction unit cell composite body includes an electrochemical reaction unit cell, and an interconnector which has a first through hole defining a fuel gas flow channel and which is disposed on the side toward an anode of the electrochemical reaction unit cell. The interconnector includes a coating forming a first surface of the interconnector opposite the anode of the electrochemical reaction unit. The coating includes a first coating and a second coating having reduction resistance higher than that of the first coating. The first coating forms a first surface region which is a portion of the first surface of the interconnector and which is located away from the first through hole. The second coating forms a second surface region which is a portion of the first surface of the interconnector, which surrounds the first through hole, and which is located between the first coating and the first through hole.