Barrier Coating for Solid Oxide Fuel Cell Interconnects
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Solution Overview
Problem
Solid oxide fuel cells using chromium-containing interconnects suffer from performance degradation due to Cr-poisoning of the cathode and the formation of low conductivity strontium chromate at the interface between the interconnect and cathode layers, leading to reduced efficiency and shorter life cycles.
Innovation Solution
A barrier coating is applied between the cathode layer and the chromium-containing interconnect to prevent the formation of strontium chromate, comprising a strontium composition on a ceramic electrolyte layer, which substantially inhibits the migration of strontium and chromium, thereby maintaining optimal electrical characteristics and fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chromium-containing interconnects are used in solid oxide fuel cells, then oxidation resistance is improved, but strontium chromate formation at the cathode interface occurs causing performance degradation
Solution Approach 1:
A barrier coating layer is introduced between the chromium-containing interconnect and the strontium-based cathode to prevent direct contact and chemical reaction. This intermediary layer blocks the diffusion of chromium and strontium ions, eliminating the harmful strontium chromate formation while preserving the oxidation resistance of the interconnect material.
Solution Approach 2:
The interface between the interconnect and cathode is segmented by inserting a distinct barrier coating layer. This segmentation separates the chromium-containing interconnect from the strontium-based cathode, preventing the formation of strontium chromate at the interface while maintaining the functional properties of both materials.
2Reliability
If chromium migrates into the cathode to form Cr-poisoning deposits, then electrical conductor protection is improved, but active electrochemical sites are blocked causing performance degradation
Solution Approach 1:
The barrier coating serves as an intermediary layer that prevents chromium migration from the interconnect into the cathode. By blocking the diffusion path of chromium ions, the coating protects the active electrochemical sites of the cathode from poisoning while allowing the interconnect to maintain its oxidation resistance.
Solution Approach 2:
The harmful chromium migration and cathode poisoning mechanism is extracted or removed from the system by introducing the barrier coating. This coating effectively takes out the chromium diffusion pathway, preventing Cr-poisoning of the cathode while preserving the beneficial oxidation protection of the chromium-containing interconnect.
3Stability of the object's composition
If the strontium chromate layer thickness increases during prolonged operation, then interface stability is improved, but electrical conductivity is reduced causing performance degradation
Solution Approach 1:
The barrier coating acts as a stable intermediary layer that prevents the formation and growth of strontium chromate at the interface. By blocking the diffusion of strontium and chromium ions, the coating eliminates the source of strontium chromate formation, thereby maintaining both interface stability and electrical conductivity throughout prolonged operation.
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 barrier coating effectively reduces the formation of strontium chromate, enhancing the electrical conductivity and extending the operational life of solid oxide fuel cells by limiting the increase in area-specific resistance to no more than 10-20% compared to cells without the coating.
Implementation Method 1
forming a barrier layer between the cathode layer and an overlying interconnect structure comprising chromium, so as to substantially prevent the formation of strontium chromate
Data Source
AI summary
A method of preparing a solid oxide fuel cell is described herein, as well as the fuel cell itself. The method comprises forming a cathode layer comprising a strontium composition on a ceramic electrolyte layer; and forming a barrier layer between the cathode layer and an overlying interconnect structure comprising chromium, so as to substantially prevent the formation of strontium chromate.