Fuel Cell Intermediate Layer Mitigates Thermal Stress
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Solution Overview
Problem
Fuel cells with multiple layers experience thermal stress-induced cracking and peeling due to differences in thermal expansion and firing contraction between layers, leading to reduced performance and lifespan.
Innovation Solution
Incorporating an intermediate layer with a higher pore ratio between the solid electrolyte and barrier layers, composed of zirconium and cerium, to mitigate thermal stress and prevent peeling by reducing stress between the barrier and electrolyte layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple layers with different compositions are used in the fuel cell, then the functional performance is improved, but thermal stress-induced cracking and peeling occur due to differences in thermal expansion and firing contraction
Solution Approach 1:
A buffer layer comprising a porous transition layer and a porous barrier layer is provided between the solid electrolyte layer and the cathode. The porous transition layer has a pore ratio of 30-80%, and the porous barrier layer has a pore ratio of 10-50%. This intermediary buffer layer structure mitigates the direct thermal stress between layers with different thermal expansion coefficients, preventing cracking and peeling while maintaining the functional performance of the fuel cell.
Solution Approach 2:
The buffer layer utilizes porous materials with controlled pore ratios. The porous transition layer (30-80% pore ratio) and porous barrier layer (10-50% pore ratio) provide a gradient in mechanical properties that reduces thermal stress concentration. The porous structure allows for stress distribution and accommodation during thermal cycling, preventing the formation of cracks and peeling between layers.
2Stability of the object's composition
If a dense barrier layer is used to prevent peeling, then layer adhesion is improved, but thermal stress accumulates leading to cracking
Solution Approach 1:
The buffer layer is divided into two regions with different pore ratios: the porous transition layer (30-80% pore ratio) adjacent to the solid electrolyte layer and the porous barrier layer (10-50% pore ratio) adjacent to the cathode. This local quality variation creates a gradient in mechanical properties, allowing the transition layer to accommodate thermal stress while the barrier layer provides adhesion stability, thereby preventing both cracking and peeling.
Solution Approach 2:
The pore ratio parameter is varied across the buffer layer structure. The porous transition layer has a higher pore ratio (30-80%) to reduce thermal stress, while the porous barrier layer has a lower pore ratio (10-50%) to maintain adhesion. This parameter change creates an optimal balance between stress relief and layer bonding, preventing both cracking and peeling.
3Stress or pressure
If the pore ratio of the intermediate layer is increased to reduce stress, then thermal stress resistance is improved, but structural integrity may be compromised
Solution Approach 1:
The buffer layer is segmented into two distinct layers: the porous transition layer and the porous barrier layer, each with different pore ratios. The porous transition layer (30-80% pore ratio) provides thermal stress resistance, while the porous barrier layer (10-50% pore ratio) maintains structural integrity. This segmentation allows each layer to optimize its function without compromising the overall structure.
Solution Approach 2:
The buffer layer is constructed as a composite structure with two porous layers having different pore ratios. The porous transition layer (30-80% pore ratio) and porous barrier layer (10-50% pore ratio) work together as a composite system, where the higher-pore layer reduces thermal stress and the lower-pore layer provides structural support, achieving both stress resistance and structural integrity.
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 intermediate layer effectively reduces thermal stress and prevents peeling between the barrier and electrolyte layers, enhancing the durability and performance of the fuel cell by maintaining layer integrity under temperature fluctuations.
Implementation Method 1
the coefficient of thermal expansion and/or the firing contraction amount in the respective layers differs in response to heat produced during manufacture and/or use
Implementation Method 2
The intermediate layer includes pores, and therefore enables a reduction in the stress between the barrier layer and the solid electrolyte layer
Data Source
AI summary
A fuel cell is provided that includes an anode, a cathode, a solid electrolyte layer, a barrier layer, and an intermediate layer. The solid electrolyte layer includes zirconium and is provided between the anode and the cathode. The barrier layer includes cerium and is provided between the solid electrolyte layer and the cathode. The intermediate layer includes zirconium and cerium, and has a first surface facing the solid electrolyte layer, a second surface facing the barrier layer, and pores. The pore ratio of the intermediate layer is higher than the pore ratio of the barrier layer.