Fuel Cell Stack Rework by Isolating Defective Membrane Cells
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Solution Overview
Problem
Assembled solid oxide cell stacks for SOEC systems are deemed defective if any single membrane electrode unit is faulty, leading to performance drops and accelerated degradation of adjacent cells, as the stack cannot be disassembled for replacement, resulting in a domino effect of impaired neighboring cells.
Innovation Solution
A method for quality testing and post-processing of cell stacks involves measuring electrical parameters and pressure tightness of each membrane electrode cell during or after joining, identifying defective cells, and electrically short-circuiting and gas-tight sealing them using a high-temperature-resistant bridge, allowing the stack to function despite defective cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single defective membrane electrode unit causes the entire stack to be deemed defective, then quality control standards are maintained, but stack availability and productivity are reduced due to the domino effect of degradation
Solution Approach 1:
The patent divides the cell stack into individually addressable membrane electrode units, each with separate electrical connections through interconnectors. This segmentation allows defective units to be identified and isolated without affecting the operational status of other units in the stack, resolving the contradiction between maintaining quality standards and preserving stack productivity.
2Strength
If the stack is permanently held under mechanical tension to maintain joining, then structural integrity is maintained, but defective cells cannot be replaced or removed
Solution Approach 1:
The patent introduces a reversible electrical connection mechanism through the interconnector design, allowing the electrical circuit to be dynamically reconfigured. Defective cells can be electrically bypassed or isolated while maintaining the mechanical joining structure, enabling repair operations without compromising structural integrity.
3Measurement precision
If electrical parameters are measured for each individual cell to identify defects, then defect detection precision is improved, but measurement complexity and time increase
Solution Approach 1:
The interconnector design serves multiple functions: it provides mechanical support for the membrane electrode units, establishes electrical connections for current flow, and enables electrical measurement capabilities for defect detection. This multi-functionality allows individual cell characterization without requiring separate measurement systems for each cell.
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
Enables continued operation of cell stacks with defective cells by identifying and isolating them, preventing further degradation and maintaining overall stack performance.
Implementation Method 1
measuring, in particular by means of a measuring device, electrical parameters, in particular the internal resistance, of each individual membrane electrode cell
Implementation Method 2
electrically short-circuiting and gas-tight sealing them using a high-temperature-resistant bridge
Data Source
Figure 1
Figure 2
AI summary
A method for quality control and rework of an assembled cell stack with a plurality of membrane electrode cells arranged in a stack, comprising the following steps: • measuring at least one electrical parameter of at least one membrane electrode cell, • measuring the gas pressure tightness of at least one membrane electrode cell or of the cell stack, • detecting one or more defective membrane electrode cells, depending on the measured at least one electrical parameter and/or the measured pressure tightness, and • stopping the membrane electrode cell(s) detected as defective, wherein the stopping process comprises the following steps: electrically short-circuiting the membrane electrode cell detected as defective or short-circuiting and making it technically gas-tight.