Metal Supported Solid Oxide Fuel Cell Anode REDOX Stability
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Solution Overview
Problem
Metal-supported solid oxide fuel cells (SOFCs) face challenges with REDOX stability due to the oxidation of nickel in the anode, leading to volume changes and potential cell failure during repeated reduction-oxidation cycles, which is exacerbated by the use of copper's low melting point and poor catalytic activity, making it difficult to achieve stable operation at lower temperatures.
Innovation Solution
A process involving a green anode layer with nickel oxide, copper oxide, and rare earth-doped ceria applied to a stainless steel substrate, compressed, and sintered at temperatures between 950 to 1100°C to form a robust ceramic backbone, enhancing sintering and stability, and allowing for lower operating temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If nickel is used as the anode material to provide high catalytic activity and electronic conductivity, then the fuel cell performance is improved, but the REDOX stability deteriorates due to volume change during oxidation
Solution Approach 1:
The patent uses a composite anode material consisting of nickel particles dispersed in a porous ceramic matrix (electrolyte material). This composite structure allows the nickel to provide catalytic activity and electronic conductivity while the ceramic matrix provides structural stability and resists volume change during REDOX cycling, thus resolving the contradiction between performance and reliability
Solution Approach 2:
The anode is designed with a specific microstructure where nickel particles are distributed within a porous ceramic framework. The local ceramic phase provides mechanical support and dimensional stability at the particle level, while the nickel particles maintain their catalytic function, achieving both performance and stability through localized material properties
2Reliability
If copper is added to improve sintering and stability, then the REDOX stability is improved, but the operating temperature must be reduced due to copper's low melting point
Solution Approach 1:
The patent modifies the sintering temperature parameter to be below the melting point of copper (e.g., 950-1100°C), allowing copper to be incorporated into the anode structure without causing excessive sintering or melting. This parameter change enables the use of copper for improved REDOX stability while maintaining structural integrity at lower operating temperatures
3Quantity of substance
If anode support is used to reduce material usage, then the thickness of electrochemically active layers is reduced, but the cell becomes prone to catastrophic failure during REDOX cycling
Solution Approach 1:
The anode is designed as a composite structure with a ceramic matrix providing mechanical strength and a metal phase providing conductivity and catalysis. This composite architecture allows the anode to be thinner (reducing material usage) while the ceramic backbone maintains structural integrity during REDOX cycling, preventing catastrophic failure
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 solution provides improved REDOX stability and sintering of the anode, reducing the risk of cell failure and enabling operation at lower temperatures, facilitating the use of copper without compromising performance, and allowing for the use of thinner electrochemically active layers.
Implementation Method 1
sintering the green anode layer to form a composite including oxides of nickel, copper, and a rare earth-doped ceria
Implementation Method 2
the metallic nickel which has been formed by the reduction of sintered nickel oxide
Implementation Method 3
the metallic nickel will oxidise back to nickel oxide. This oxidation is associated with a volume increase of greater than approximately 40%
Data Source
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AI summary
A process for forming a metal supported solid oxide fuel cell, the process comprising the steps of: a) applying a green anode layer including nickel oxide, copper oxide and a rare earth-doped ceria to a metal substrate; b) firing the green anode layer to form a composite including oxides of nickel, copper, and a rare earth-doped ceria; c) providing an electrolyte; and d) providing a cathode. Metal supported solid oxide fuel cells comprising an anode a cathode and an electrolyte, wherein the anode includes nickel, copper and a rare earth-doped ceria, fuel cell stacks and uses of these fuel cells.