Zr-Modified Reaction Preventing Layer for Solid Oxide Fuel Cells
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Solution Overview
Problem
The generation of SrZrO3 in solid oxide fuel cells and electrolysis cells increases electric resistance, impairing performance due to the diffusion of Sr from the cathode into the electrolyte layer, and excessive diffusion of elements from the cathode can reduce reliability.
Innovation Solution
Incorporating Zr into the reaction preventing layer in an amount of 0.015 wt% or more to trap Sr and prevent its diffusion, while maintaining Zr at 1 wt% or less to avoid excessive element diffusion, thereby preventing the formation of high-resistance SrZrO3 and maintaining cathode reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reaction preventing layer containing GDC is disposed between the cathode and the electrolyte layer to prevent SZO generation, then Sr diffusion into the electrolyte layer is prevented, but the solid solution layer generated by interdiffusion has high resistance and increases electric resistance in the first direction
Solution Approach 1:
The invention changes the chemical composition parameters of the reaction preventing layer by incorporating Zr in a specific amount (0.01-10 wt%). This parameter modification allows the layer to trap Sr effectively while controlling the formation of high-resistance solid solution layers, thus resolving the contradiction between preventing SrZrO3 generation and maintaining low electric resistance.
Solution Approach 2:
The invention creates a composite reaction preventing layer by combining GDC with Zr-containing materials. This composite structure enables the layer to simultaneously perform Sr diffusion prevention and resistivity control, as the Zr component traps Sr while the GDC matrix maintains ionic conductivity, thereby resolving the technical contradiction.
2Reliability
If the thickness of the solid solution layer is increased to prevent Sr diffusion, then SrZrO3 generation is prevented, but electric resistance in the first direction increases resulting in poor electricity generation performance
Solution Approach 1:
The invention modifies the composition parameters of the reaction preventing layer by adding Zr (0.01-10 wt%), which changes the diffusion characteristics and reduces the thickness of the solid solution layer. This allows effective Sr diffusion prevention while maintaining lower electric resistance and preserving electricity generation performance.
Solution Approach 2:
The Zr-containing reaction preventing layer acts as an intermediary between the cathode and electrolyte layer. It provides a controlled diffusion path that traps Sr through Zr-Sr interactions while limiting the formation of extensive high-resistance solid solution layers, thus resolving the contradiction between diffusion prevention and performance maintenance.
3Reliability
If excessive diffusion of elements from the cathode is allowed, then Sr can reach the electrolyte layer to form SrZrO3, but other elements diffusing excessively reduce reliability due to variation in cathode composition
Solution Approach 1:
The invention applies local quality control by incorporating Zr specifically in the reaction preventing layer at a controlled concentration (0.01-10 wt%). This localized Zr distribution creates a specific trapping zone that selectively captures Sr diffusion while allowing the rest of the cathode structure to maintain its composition stability, thus preventing both SrZrO3 formation and excessive element diffusion.
Solution Approach 2:
The invention changes the compositional parameter of the reaction preventing layer by adding Zr, which modifies the diffusion field characteristics. This parameter change creates a gradient that facilitates Sr trapping while restricting excessive diffusion of other cathode elements, thereby simultaneously preventing SrZrO3 formation and maintaining cathode composition stability.
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 approach effectively prevents the impairment of electrochemical reaction performance by blocking SrZrO3 formation and reducing cathode composition variations, ensuring stable and reliable operation of the unit cells.
Implementation Method 1
the diffusion of Sr (strontium) contained in the cathode toward the electrolyte layer
Implementation Method 2
Sr diffused from the cathode toward the electrolyte layer can be trapped by Zr distributed in the reaction preventing layer
Implementation Method 3
interdiffusion between the electrolyte layer and the reaction preventing layer around the boundary therebetween
Data Source
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AI summary
An object is to prevent impairment of the performance of an electrochemical reaction unit cell while preventing a reduction in the reliability of a cathode. The electrochemical reaction unit cell includes an electrolyte layer containing Zr, an anode disposed on one side of the electrolyte layer in a first direction, a cathode containing Sr and disposed on the other side of the electrolyte layer in the first direction, and a reaction preventing layer disposed between the electrolyte layer and the cathode. The reaction preventing layer contains Zr in an amount of 0.015 (wt%) to 1 (wt%).