Solid Oxide Fuel Cell Current Collection Assisting Layer
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Solution Overview
Problem
High operation temperatures in solid oxide fuel cells cause thermal expansion differences between the fuel cell unit and its case, leading to flexural deformation and potential breakage of the contact between the current collection assisting layer and the air electrode, increasing electric resistance.
Innovation Solution
The current collection assisting layer is designed with lower flexural rigidity in the direction perpendicular to the gas channel direction than in the gas channel direction, allowing it to follow the fuel cell unit's deformation and maintain contact, thereby preventing increased electric resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-temperature gas is supplied to rapidly raise the temperature and reduce start-up time, then the power generation efficiency is improved, but a large temperature difference between the fuel cell unit and the case occurs, resulting in large difference in thermal expansion
Solution Approach 1:
The patent changes the physical state of the current collection assisting layer from rigid to flexible by controlling its sintering degree, allowing it to accommodate thermal expansion differences during rapid heating without compromising electrical conductivity
Solution Approach 2:
The patent creates a composite structure where the current collection assisting layer combines flexible properties (to accommodate thermal expansion) with sufficient electrical conductivity (to maintain power generation efficiency) through controlled sintering of metal particles
2Stability of the object's composition
If the fuel cell unit is restrained by the case, then structural stability is improved, but the fuel cell unit cannot expand outward, causing flexural deformation
Solution Approach 1:
The patent adjusts the flexural rigidity parameter of the current collection assisting layer by controlling the sintering degree of metal particles, transforming it from a rigid structure prone to breakage to a flexible structure that can deform without breaking while maintaining electrical continuity
3Strength
If the current collection assisting layer is rigid, then structural strength is improved, but contact breakage occurs due to thermal expansion-induced flexural deformation, increasing electric resistance
Solution Approach 1:
The patent optimizes the sintering degree parameter to achieve a balance between structural strength and flexibility, creating a current collection assisting layer that is strong enough to maintain structural integrity but flexible enough to follow fuel cell unit deformation without contact breakage
Solution Approach 2:
The patent uses a porous structure with metal particles that can be easily sintered to create a sacrificial flexible layer that absorbs deformation stress through controlled porosity and particle bonding
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 design reduces the area-specific resistance of the solid oxide fuel cell by at least 25% by preventing contact breakage and allowing the current collection assisting layer to deform with the fuel cell unit, ensuring continuous conductivity.
Implementation Method 1
the current collection assisting layer has such flexural rigidity that is less in a direction perpendicular to the air channel extending direction than in the air channel extending direction
Implementation Method 2
a large temperature difference between the fuel cell unit and the like and a case, which results in a large difference in thermal expansion between the fuel cell unit and the like and the case
Data Source
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AI summary
A solid oxide fuel cell of the present invention includes: a fuel cell unit including a fuel electrode, a solid electrolyte and an air electrode layered in the written order; a current collection assisting layer that is layered on an air electrode side of the fuel cell unit; air channels disposed on the air electrode side; and fuel gas channels disposed on a fuel electrode side. The air channels and the fuel gas channels are defined and formed by a current collector on the current collection assisting layer and a current collector on the fuel electrode side of the fuel cell unit. The air channels and the fuel gas channels extend in the same direction that is perpendicular to the fuel cell unit layering direction. The current collector on the air electrode side is fixed to the current collection assisting layer at first fixing portions that extend in the air channel extending direction, and the current collector on the fuel electrode side is fixed to the fuel electrode side of the fuel cell unit at second fixing portions that extend in the fuel gas channel extending direction. The solid oxide fuel cell is characterized in that the current collection assisting layer has such flexural rigidity that is lower in a direction perpendicular to the air channel extending direction than in the air channel extending direction.