SOFC Interconnect with Seamless Porous-Dense Transition
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Solution Overview
Problem
Existing solid oxide fuel cell (SOFC) designs face challenges with residual stress and cracking due to sharp transitional corners and seams between porous and dense metal interfaces, leading to low open circuit voltage and poor fuel utilization, especially when using thermal spray deposition techniques.
Innovation Solution
A monolithic manifold and interconnect structure with a seamless transition between dense and permeable surfaces, allowing for full coverage of electrode and electrolyte layers without stress-related defects, achieved through a flat interconnect junction where both surfaces are in the same plane, enabling robust and large-scale cell formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If large perforations or interconnected porosity are used in the interconnect fuel flow field, then sufficient fuel gas can reach the anode and electrolyte interface to minimize mass transport polarization, but the interconnect surface cannot provide a smooth substrate for planar coating deposition, resulting in gross defects and low open circuit voltage
Solution Approach 1:
The interconnect is designed with spatially varying properties: a porous region with interconnected porosity (30-70% porosity, pore sizes 10-100 μm) for fuel transport, and a dense region with smooth surface (Ra < 10 μm) for coating deposition. The transition region gradually changes porosity from porous to dense, creating a gradient structure that satisfies both fuel delivery and coating quality requirements in different locations.
2Ease of operation
If porous metal foam is used to provide fuel flow paths, then adequate fuel can reach the anode and electrolyte interface while maintaining hermetic electrolyte coating, but sharp transitional corners and seams at the porous-dense metal interface cause stress concentrations and electrolyte cracking
Solution Approach 1:
The transition region between porous and dense regions is designed with curved, gradual transitions instead of sharp corners or seams. The porosity gradient creates a smooth morphological transition that eliminates stress concentration points, preventing electrolyte cracking while maintaining both fuel delivery and coating hermeticity.
3Productivity
If traditional ceramic sintering technology is used for anode-supported SOFCs, then manufacturing can be achieved, but the maximum manufacturable cell size is limited at high yields and large capital investment is required
Solution Approach 1:
The invention changes the manufacturing approach from traditional ceramic sintering to thermal spray deposition on metal interconnects. This parameter change enables larger cell sizes (up to 100 cm² demonstrated) with higher manufacturing yields and reduced capital investment, while maintaining the required coating hermeticity and performance.
4Manufacturing precision
If the interconnect surface is made smooth for uniform coating deposition, then electrode and electrolyte layers can be deposited without gross defects, but the fuel flow field cannot provide sufficient fuel gas transport to the electrode interface
Solution Approach 1:
The interconnect is segmented into functionally distinct regions: a porous region for fuel transport, a transition region for gradual property change, and a dense region for smooth coating deposition. This segmentation allows each region to optimize its specific function without compromising the overall system performance.
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 minimizes defects and stress, ensuring hermetic electrolyte coverage and efficient fuel delivery, thereby enhancing the open circuit voltage and fuel utilization of SOFCs, allowing for larger cell sizes and higher production yields.
Implementation Method 1
metal interconnect-supported SOFCs utilizing thermal spray deposition offer a variety of manufacturing benefits
Implementation Method 2
The hermetic electrolyte conducts the oxygen ions at high temperature to an anode
Implementation Method 3
A cathode reduces oxygen on one side and supplies oxygen ions to a hermetic electrolyte
Implementation Method 4
The hermetic electrolyte conducts the oxygen ions at high temperature to an anode, where the oxygen ions oxidize hydrogen to form water
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A solid oxide fuel cell (SOFC) manifold and interconnect structure 20 includes a manifold that has a dense and hermetic planar surface 21 that is impervious to fuel gas used with the corresponding SOFC. A porous material 22 includes a permeable planar surface 23 that is in lateral contact with the planar surface 21 of the manifold to form an electrode interconnect. The exposed surface of the junction 44 between the dense and hermetic planar surface 21 and the permeable planar surface 22 is substantially flat and devoid of discontinuities, corners and seams. The dense and hermetic planar surface 21, the permeable planar surface 22 and the exposed surface of the junction lay in a single common plane suitable for thermal deposition of electrode and electrolyte layers 19.