Flat Interconnector Plates for Fuel Cell Stacks
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Solution Overview
Problem
Conventional repeating units for electrochemical cell stacks require additional steps like annealing and reforming due to warping of interconnector plates, increasing production complexity and effort, especially for high-temperature fuel cells where thermal expansion coefficients cause deformations during soldering.
Innovation Solution
A repeating unit design featuring unshaped, flat interconnector plates made from electrically conductive materials, soldered together with the cathode-electrolyte-anode unit, including a conductive porous contact element to prevent deformation, using metal or glass solder, and pre-assembling layers before heating to minimize thermal expansion issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional interconnector plates are used with channel structures, then electrical connection and material transport are achieved, but warping occurs during joining requiring additional annealing and reforming steps
Solution Approach 1:
The invention changes the geometric parameters of the interconnector plate by using a flat design without channel structures. This parameter change eliminates the warping issue during joining while maintaining electrical connection functionality through alternative means (edge-area contact and porous contact elements).
Solution Approach 2:
The invention extracts the channel structure from the interconnector plate design, removing the source of warping. The material transport function is then achieved through separate porous contact elements, allowing the interconnector plate to remain flat and simple during manufacturing.
2Reliability
If interconnector plates are joined by soldering, then electrical connection is achieved, but thermal expansion coefficients cause deformation during the heating process
Solution Approach 1:
The invention changes the joining parameters by using edge-area soldering instead of full-surface soldering. This reduces the thermal mass and heating time, minimizing thermal expansion effects. The flat interconnector plate design also reduces differential thermal expansion stresses.
Solution Approach 2:
The invention introduces porous contact elements as intermediaries between the interconnector plate and the cathode-electrolyte-anode unit. These elements accommodate thermal expansion differences while maintaining reliable electrical connection, acting as a buffer during the soldering process.
3Ease of manufacture
If flat unshaped interconnector plates are used, then production is simplified and warping is prevented, but additional porous contact elements are required for material transport
Solution Approach 1:
The invention merges multiple functions into the porous contact elements: electrical connection, material transport (fuel and oxidant supply), and mechanical support. This consolidation offsets the added component count by eliminating the complex channel structures from the interconnector plate itself.
Solution Approach 2:
The invention applies local quality by placing porous contact elements only at specific locations (edge areas and active regions) where material transport is needed, rather than incorporating channels throughout the entire interconnector plate. This maintains simplicity where needed while adding functionality where required.
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 approach simplifies the production of electrochemical cell stacks by eliminating the need for additional processing steps, reducing deformation risks, and enabling efficient assembly of high-temperature fuel cells with improved thermal stability and electrical insulation.
Implementation Method 1
the said layers and the cathode-electrolyte-anode unit are soldered together by heating together. A metal solder and/or a glass solder can be used as the soldering paste
Implementation Method 2
Deformation caused by different thermal expansion coefficients of the layers of the interconnector plate and the cathode-electrolyte-anode unit can be prevented even better during soldering
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a repetition unit for a stack of electrochemical cells, having a cathode-electrolyte-anode unit (1) and having a first layer (2) and at least one further layer (3, 4) of an interconnector plate resting thereon, with the first layer (2) being manufactured from sheet metal and making electrical contact with the cathode-electrolyte-anode unit (1), while the at least one further layer (3, 4) is cut out in an active area, furthermore with the at least one further layer (3, 4) being composed of a formed flat material, and the first layer (2) also being formed in an edge area surrounding the active area, and with the cathode-electrolyte-anode unit (1) as well as all the said layers (2, 3, 4) being soldered to one another in the edge area. The invention also relates to a corresponding stack arrangement of electrochemical cells, and to a method for production of a repetition unit such as this.