Cross-Flow SOFC Interconnect Layout to Prevent Thermal Stress Cracks
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Solution Overview
Problem
Conventional fuel cell stacks face issues with non-uniform fuel distribution, reduced active area, and thermal stress cracks due to complex fuel manifolds and through-holes, leading to lower stack yield and operational efficiency.
Innovation Solution
The use of cross-flow interconnects with fuel inlets and outlets on the perimeter, coated with lanthanum strontium manganite (LSM) or (Mn, Co)3O4 spinel, and dielectric layers to prevent electrical shorting, along with a chromium-iron alloy for improved thermal expansion match, enhances uniform fuel distribution and reduces thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional fuel manifolds and through-holes are used for fuel distribution, then fuel can be supplied to the fuel cell stack, but non-uniform fuel distribution and reduced active area occur
Solution Approach 1:
The patent removes the conventional fuel manifold structure and through-holes from the interconnect design. Instead, fuel is supplied through perimeter channels formed by recessed regions in the interconnect plate, eliminating the need for internal through-holes that reduce active area and cause non-uniform distribution.
Solution Approach 2:
The patent transitions from internal through-hole fuel distribution to perimeter-based fuel supply. Fuel channels are formed along the peripheral edges of the interconnect, utilizing the boundary dimension rather than penetrating through the plate, thereby maximizing the active area while ensuring uniform fuel distribution.
2Ease of operation
If complex fuel manifolds are used for fuel distribution, then fuel can be delivered to cells, but device complexity increases
Solution Approach 1:
The complex internal fuel manifold structure is completely removed. The simplified design uses perimeter channels formed by recessed regions at the edges of the interconnect, eliminating the need for intricate internal piping and through-holes while maintaining effective fuel distribution.
Solution Approach 2:
The fuel distribution function is merged with the interconnect structure itself. The recessed peripheral regions of the interconnect plate directly form the fuel channels, combining the structural and flow distribution functions into a single integrated component.
3Ease of manufacture
If interconnects are placed into the electrochemical cell stack without creep flattening, then assembly is simpler, but thermal stress cracks occur
Solution Approach 1:
The interconnect undergoes creep flattening treatment before being assembled into the fuel cell stack. This preliminary action pre-stresses the interconnect to match the thermal expansion characteristics of the ceramic cells, preventing thermal stress cracks during operation while maintaining a relatively simple assembly process.
4Adaptability or versatility
If gas flow separator plate is used as interconnect, then electrical connection is achieved, but thermal stress cracks occur due to material properties
Solution Approach 1:
The interconnect is constructed as a composite structure with a metal plate base layer providing mechanical strength and thermal expansion matching, combined with a conductive coating layer (such as nickel or nickel alloy) that provides electrical conductivity. This composite approach separates the conflicting requirements of thermal compatibility and electrical conductivity.
Solution Approach 2:
The interconnect material properties are optimized by selecting metal alloys with thermal expansion coefficients matched to the ceramic cells, and by applying conductive coatings with appropriate thickness and composition. The creep flattening process also modifies the physical parameters of the interconnect to reduce thermal stress.
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 achieves uniform fuel distribution, maximizes fuel cell active area, and minimizes thermal stress cracks, thereby improving stack yield and operational efficiency without increasing the system footprint.
Implementation Method 1
a coating comprising at least one of lanthanum strontium manganite (LSM) or (Mn, Co)3 O4 spinel (MCO) located on the air-side ribs but not on the riser seal surfaces
Implementation Method 2
riser seal surfaces disposed on the first and second peripheral edges of the interconnect, wherein the riser seal surfaces surround the fuel inlets and outlets
Implementation Method 3
fuel inlets and outlets that extend through the interconnect adjacent to opposing first and second peripheral edges of the interconnect
Implementation Method 4
a chromium-iron alloy for improved thermal expansion match
Implementation Method 5
creep flattening the interconnect prior to placing the interconnect into the electrochemical cell stack
Data Source
AI summary
A method of making an interconnect for an electrochemical cell stack includes providing the interconnect, and creep flattening the interconnect prior to placing the interconnect into the electrochemical cell stack.