Zirconia Electrolyte Thermal Shock Resistance
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Solution Overview
Problem
Fuel cell solid electrolyte layers experience thermal shock damage due to excess fuel gas reacting with air during startup or restart, leading to potential damage at the exhaust port side.
Innovation Solution
Incorporating a zirconia-based solid electrolyte layer with a specific structure, including a first area near the anode with a higher intensity ratio of tetragonal to cubic zirconia in the Raman spectrum, and a second area with a lower intensity ratio, to reduce thermal shock damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If excess fuel gas is discharged through the exhaust port to maintain operation temperature, then the fuel cell can maintain appropriate operation temperature, but thermal shock damage occurs to the solid electrolyte layer at the exhaust port side during startup or restart
Solution Approach 1:
The solid electrolyte layer is designed with different zirconia crystal phase compositions at different locations. The first area (within 3 μm from anode side surface) has a higher intensity ratio of tetragonal to cubic zirconia, while the second area has a lower intensity ratio. This local quality variation makes the distal end portion more resistant to thermal shock damage while maintaining overall operational temperature.
Solution Approach 2:
The solid electrolyte layer uses a composite zirconia-based material containing both tetragonal and cubic zirconia phases with different proportions in different areas. This composite structure combines the thermal shock resistance of tetragonal zirconia in the first area with the properties of cubic zirconia in the second area, achieving both temperature maintenance and damage resistance.
2Productivity
If the solid electrolyte layer is positioned at the distal end to enable fuel gas discharge, then combustion can occur for temperature maintenance, but damage occurs to the distal end side power generation unit
Solution Approach 1:
The distal end portion of the solid electrolyte layer is specifically engineered with a higher concentration of tetragonal zirconia in the first area (within 3 μm from anode side surface). This local quality enhancement provides superior thermal shock resistance exactly where needed - at the distal end power generation unit - allowing it to withstand the thermal stresses of combustion while maintaining power generation capability.
3Ease of manufacture
If uniform zirconia composition is used throughout the solid electrolyte layer, then manufacturing is simplified, but thermal shock resistance at the distal end is insufficient
Solution Approach 1:
Rather than using uniform composition, the invention applies local quality variation by creating a first area with higher tetragonal to cubic zirconia intensity ratio within 3 μm from the anode side surface. This targeted composition variation provides enhanced thermal shock resistance at the critical distal end region while keeping the manufacturing process relatively simple through controlled deposition or sintering techniques.
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 structured zirconia-based solid electrolyte layer effectively minimizes damage to the electrolyte layer during fuel cell operation, maintaining performance and reducing oxide ion conductivity declines.
Implementation Method 1
at the beginning of operation of the fuel cell, the excess fuel gas reacts with air to fire, which causes a thermal shock on a solid electrolyte layer of the cell
Implementation Method 2
An intensity ratio of tetragonal zirconia to cubic zirconia in a Raman spectrum in the first area is greater than an intensity ratio of tetragonal zirconia to cubic zirconia in the Raman spectrum in the second area
Implementation Method 3
fuel cell stacks that include fuel cells and a manifold supporting base ends of the fuel cells
Implementation Method 4
reducing oxide ion conductivity declines
Data Source
AI summary
An electrochemical cell stack according to a first aspect of the present invention includes an electrochemical cell and a manifold supporting a base end of the electrochemical cell. The electrochemical cell includes an electric insulative support substrate and a plurality of power generation units disposed on the support substrate. Additionally, a gas flow path is provided in the support substrate. Each of the plurality of power generation units includes an anode, a cathode, and a solid electrolyte layer disposed between the anode and the cathode. Additionally, the solid electrolyte layer contains a zirconia-based material as a main component thereof. In a distal end side power generation unit, which is farthest from the manifold among the plurality of power generation units, the solid electrolyte layer includes a first area covering within 3 μm from an anode side surface, and a second area provided on the first area. An intensity ratio of tetragonal zirconia to cubic zirconia in a Raman spectrum in the first area is greater than an intensity ratio of tetragonal zirconia to cubic zirconia in the Raman spectrum in the second area.