Chromium-Getter Contact Layer for Solid Oxide Fuel Cells
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Solution Overview
Problem
Volatile chromium species from stainless steel components in high-temperature fuel cell stacks degrade cathode performance, especially exacerbated by humidity, leading to electrochemical performance degradation.
Innovation Solution
A chromium-getter contact layer, comprising materials like lanthanum oxide, lanthanum carbonate, or barium carbonate, is applied between the fuel cell electrodes and interconnects to react with and capture chromium vapor, reducing contamination and performance degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stainless steel interconnects are used in fuel cell stacks, then mechanical strength and electrical conductivity are improved, but chromium vapor is released that degrades cathode performance
Solution Approach 1:
A contact layer comprising a chromium-getter material is introduced between the stainless steel interconnect and the cathode electrode. This intermediary layer reacts with chromium vapor to form a stable chromium-rich phase, preventing chromium from depositing on the cathode and maintaining cathode performance while allowing the stainless steel interconnect to provide its mechanical and electrical functions
Solution Approach 2:
The chromium vapor, which is a harmful byproduct of stainless steel operation, is converted into a beneficial protective layer. The chromium-getter material reacts with chromium vapor to form a stable chromium-rich phase at the contact layer, effectively trapping the harmful chromium and preventing it from damaging the cathode
2Productivity
If humidity is present in the fuel cell environment, then electrochemical reactions are enhanced, but chromium deposition on cathode is exacerbated
Solution Approach 1:
The contact layer with chromium-getter material serves as a protective intermediary between the humid environment and the cathode. It selectively reacts with chromium vapor in the presence of humidity, forming a stable chromium-rich phase that prevents chromium deposition on the cathode while allowing the humid environment to maintain its beneficial effect on electrochemical reactions
3Reliability
If a contact layer with chromium-getter material is added, then chromium contamination is reduced, but device complexity increases
Solution Approach 1:
The chromium-getter material is applied locally only at the contact layer between the interconnect and the cathode, where chromium deposition is most problematic. This localized approach provides targeted protection against chromium contamination without requiring modification of the entire fuel cell stack, thereby limiting the increase in device complexity
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
The chromium-getter contact layer effectively captures chromium species, significantly reducing cathode degradation and maintaining fuel cell performance over extended runtime, even in humid conditions.
Implementation Method 1
The contact layer may include a chromium-getter material... which reacts with chromium vapor in the range of 300 to 850°C
Implementation Method 2
a chromium-getter contact layer... to react with and capture chromium vapor
Data Source
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AI summary
In embodiments, a fuel cell stack is provided that includes an interconnect between a first fuel cell and a second fuel cell, and a contact layer in contact with, and disposed between, an electrode of the first fuel cell and the interconnect. The contact layer may include a chromium-getter material. This chromium-getter material may consist of lanthanum oxide, lanthanum carbonate, and/or calcium carbonate.