Fuel Cell Stack Unit Cell Degradation Evaluation
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Solution Overview
Problem
Current methods require disassembly of fuel cell stacks to evaluate unit cell degradation, which is inefficient and time-consuming.
Innovation Solution
A method and apparatus using a galvanostatic approach with a current supplying device, voltage measuring device, and physical property determining device to evaluate unit cell degradation in a fuel cell stack without disassembly, employing equations to determine parameters like Cdl, RF, and EAS from measured voltage and current changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the fuel cell stack is disassembled to evaluate unit cell degradation, then the degradation cause can be analyzed, but the evaluation time increases and efficiency decreases
Solution Approach 1:
The patent replaces mechanical disassembly operations with electrochemical measurement methods. By applying galvanostatic charging/discharging cycles and measuring voltage responses, the system can evaluate unit cell degradation (catalyst layer, electrolyte membrane, separator) without physical disassembly, thus eliminating time loss while maintaining diagnostic accuracy
Solution Approach 2:
The patent introduces electrochemical signals (current, voltage, capacitance) as intermediaries to indirectly assess unit cell degradation. Instead of directly observing physical degradation through disassembly, the system uses voltage responses during galvanostatic cycles as mediators to infer the condition of catalyst layers, membranes, and separators
2Measurement precision
If the fuel cell stack is disassembled to detect degraded cells, then the degraded unit cells can be identified, but the operational status changes and further testing is affected
Solution Approach 1:
The patent replaces mechanical disassembly with electrochemical measurement techniques. By performing galvanostatic charge-discharge cycles and analyzing voltage responses, the system can identify degraded unit cells while keeping the stack assembled and operational, thus maintaining reliability and avoiding operational status changes
Solution Approach 2:
The fuel cell stack performs self-diagnosis through electrochemical measurements. The galvanostatic cycling process causes voltage responses that reveal the condition of individual unit cells, allowing the system to detect degraded cells without external intervention or disassembly, thus maintaining operational status
3Ease of operation
If voltage measurement is performed between end plates, then the measurement setup is simple, but the voltage values represent cumulative totals and cannot identify individual degraded cells
Solution Approach 1:
The patent segments the voltage measurement by introducing intermediate connection points at separators between unit cells. Instead of measuring only between end plates, the system can measure voltage across individual cells or groups of cells by connecting to separator terminals, enabling identification of specific degraded cells while maintaining operational status
Solution Approach 2:
The patent uses separators as intermediary connection points for voltage measurement. By connecting voltage measurement devices to separator terminals rather than only end plates, the system can obtain voltage data for individual unit cells, thus identifying degraded cells without compromising measurement simplicity
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 non-invasive evaluation of unit cell degradation in fuel cell stacks, reducing detection time and allowing analysis of catalyst layer, electrolyte membrane, and catalyst support degradation without disassembly.
Implementation Method 1
a current supplying device connected to the two end plates and supplying constant current
Implementation Method 2
at least one voltage measuring device measuring voltage between two separators selected from the (n+1) separators
Implementation Method 3
Δt2 and ΔV2 are respectively time change and voltage change of an electrical double layer charging zone when the change in voltage is measured by a galvanostatic method
Implementation Method 4
QH is hydrogen adsorption/desorption charge, and Δt1 and ΔV1 are respectively time change and voltage change of a hydrogen adsorption/desorption zone
Data Source
AI summary
Disclosed are a method and an apparatus for an intact evaluation of the unit cells in a fuel cell stack. Since the degradation of the unit cells can be detected intactly, i.e. without disassembly of the stack, the time required for the detection and analysis thereof can be greatly reduced.