Fuel Cell Barrier Layer Pore Gradient 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 a barrier layer with pores between the solid electrolyte and cathode, and a buffer layer with zirconium and cerium between the barrier and electrolyte layers, to mitigate thermal stress and enhance attachment strength, thereby preventing peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple layers with different compositions are used in the fuel cell, then the functionality and performance of the fuel cell are improved, but thermal stress-induced cracking and peeling occur due to differences in thermal expansion and firing contraction between layers
Solution Approach 1:
A buffer layer comprising zirconium and cerium is introduced between the barrier layer and the solid electrolyte layer. This intermediary layer has a thermal expansion coefficient intermediate between the barrier layer and the solid electrolyte layer, thereby reducing thermal stress at the interface and preventing peeling and cracking during temperature changes.
Solution Approach 2:
The invention changes the material composition and physical parameters of the barrier layer by introducing pores. The porous structure modifies the thermal and mechanical properties of the barrier layer, reducing the mismatch in thermal expansion coefficients with adjacent layers and thereby reducing thermal stress.
2Reliability
If a barrier layer with pores is introduced to reduce thermal stress, then peeling between layers is suppressed, but the device complexity increases
Solution Approach 1:
The barrier layer is designed with non-uniform pore distribution, having a first pore ratio near the buffer layer and a second pore ratio near the cathode, with the first pore ratio being larger. This local variation in pore quality allows the barrier layer to simultaneously reduce thermal stress at critical interfaces while maintaining necessary barrier functions in other regions.
3Stress or pressure
If the first pore ratio of the first barrier layer is made larger than the second pore ratio, then thermal stress between the barrier layer and solid electrolyte layer is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The invention specifies quantitative ranges for the pore ratios (first pore ratio: 10-50%, second pore ratio: 1-30%) to achieve the desired balance between stress reduction and manufacturability. These parameter specifications provide clear manufacturing targets while ensuring the functional benefits of thermal stress reduction.
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 effectively reduces thermal stress and increases the attachment strength between layers, preventing peeling and 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 attachment strength between the barrier layer and the solid electrolyte layer is increased by the buffer layer
Data Source
AI summary
A fuel cell is provided that includes an anode, a cathode, a solid electrolyte layer, a barrier layer, and a buffer 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, with the barrier layer having pores. The buffer layer includes zirconium and cerium and is provided between the barrier layer and the solid electrolyte layer. The barrier layer has a first barrier layer provided near to the buffer layer with a first pore ratio and a second barrier layer provided between the first barrier layer and the cathode with a second pore ratio. The first pore ratio of the first barrier layer is larger than the second pore ratio of the second barrier layer.