Fuel Cell Intermediate Layer Suppresses Zr Diffusion
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Solution Overview
Problem
Fuel cells experience performance degradation due to diffusion of Zr from the solid electrolyte into the oxygen-side electrode and Sr from the oxygen-side electrode into the solid electrolyte, leading to the formation of high electrical resistance reaction layers, which impede long-term power generation efficiency.
Innovation Solution
A fuel cell design incorporating an intermediate layer with a surface region containing Zr on the solid electrolyte side and another region without Zr, ensuring tight bonding between the solid electrolyte and the intermediate layer, while preventing Sr diffusion into the solid electrolyte, thereby suppressing the formation of high electrical resistance reaction layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If co-sintering of solid electrolyte and oxygen-side electrode is performed, then manufacturing efficiency is improved, but component diffusion occurs forming high resistance reaction layers
Solution Approach 1:
An intermediate layer is introduced between the solid electrolyte and the oxygen-side electrode to prevent direct contact and diffusion between these components. This intermediary layer acts as a barrier that stops component diffusion while still allowing the co-sintering process to proceed, thus maintaining manufacturing efficiency while preventing the formation of high resistance reaction layers that would degrade power generation performance.
Solution Approach 2:
The interface between the solid electrolyte and oxygen-side electrode is segmented by introducing a distinct intermediate layer. This segmentation separates the two components that would otherwise be in direct contact during co-sintering, preventing unwanted diffusion while maintaining the structural integrity and electrical functionality of the fuel cell stack.
2Reliability
If intermediate layer is added between solid electrolyte and oxygen-side electrode, then component diffusion is prevented, but device complexity increases
Solution Approach 1:
The intermediate layer is designed with specific material composition and thickness parameters that allow it to perform multiple functions: preventing component diffusion, maintaining electrical conductivity, and ensuring mechanical stability. By carefully controlling these parameters, the layer prevents degradation without significantly complicating the device structure.
Solution Approach 2:
The intermediate layer is constructed using composite materials that combine the properties needed to prevent diffusion while maintaining electrical functionality. This composite structure provides the necessary barrier properties without requiring a complex multi-layer system, thus limiting the increase in device complexity.
3Strength
If Zr diffusion into oxygen-side electrode occurs, then bonding is enhanced, but high resistance reaction layer forms degrading performance
Solution Approach 1:
The intermediate layer serves as a mediator that allows for controlled bonding between the solid electrolyte and oxygen-side electrode while preventing uncontrolled Zr diffusion. This intermediary structure enables sufficient bonding strength for mechanical integrity while blocking the diffusion path that would lead to high resistance reaction layer formation and performance degradation.
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 power generation performance degradation by maintaining the integrity of the solid electrolyte and intermediate layer bond, and inhibiting the formation of high resistance layers, ensuring superior long-term reliability and efficiency during extended power generation.
Implementation Method 1
diffusion of Zr from the solid electrolyte into the oxygen-side electrode and Sr from the oxygen-side electrode into the solid electrolyte
Data Source
Figure 1A~1B
Figure 2~3
AI summary
The invention relates to a fuel cell having superior durability by suppressing a reaction between a component contained in a solid electrolyte and an oxygen-side electrode during a long-period operation, a fuel cell stack and a fuel cell apparatus using thereof. A fuel cell (10) includes a solid electrolyte (9) containing Zr, an intermediate layer (4) and an oxygen-side electrode (1) that are disposed in this order on one surface of the solid electrolyte (9), and a fuel-side electrode (7) disposed on another surface opposed to the oxygen-side electrode (1) of the solid electrolyte (9). The intermediate layer (4) includes a surface layer region (4a) that contains Zr and is on a side of the solid electrolyte (9), and another region (4b) except the surface layer region (4a) that does not contain Zr. Accordingly, it is possible to suppress a reaction between Zr and the oxygen-side electrode (1) and suppress power generation performance degradation of the fuel cell (10).