Method for producing a gas diffusion layer
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Solution Overview
Problem
Conventional gas diffusion layers for fuel cells often contain high concentrations of foreign ions, such as metal cations, which can contaminate the electrolyte membrane and affect cell performance, necessitating the development of layers with low ion concentrations without compromising mechanical properties.
Innovation Solution
A method for producing gas diffusion layers using dry-laid carbon fiber nonwovens subjected to hydroentanglement with water of low conductivity, followed by thermal and mechanical treatments, including pyrolysis, to achieve low ion concentrations and improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional water is used in the hydroentanglement process, then the mechanical consolidation of carbon fiber nonwovens is achieved, but the gas diffusion layer becomes contaminated with foreign ions
Solution Approach 1:
The patent changes the key parameter of water conductivity from conventional levels to ≤250 μS/cm by selecting specific water sources (distilled, deionized, or reverse osmosis water). This parameter change directly reduces foreign ion contamination in the GDL while maintaining the hydroentanglement consolidation effect, thereby improving fuel cell performance without sacrificing mechanical properties
Solution Approach 2:
The patent introduces purified water as an intermediary medium in the hydroentanglement process. This intermediary (low-conductivity water) transfers the mechanical consolidation function while minimizing the introduction of harmful ions, acting as a bridge between the hydroentanglement mechanism and the requirement for low ion contamination
2Reliability
If the conductivity of water used in hydroentanglement is reduced, then ion concentration in the gas diffusion layer decreases, but the mechanical consolidation effect may be compromised
Solution Approach 1:
The patent optimizes the conductivity parameter to a specific range (≤250 μS/cm) that balances two requirements: low enough to minimize ion contamination in the GDL, yet maintains sufficient water properties for effective hydroentanglement consolidation. This optimized parameter range ensures both low ion concentration and adequate mechanical properties
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
The resulting gas diffusion layers have significantly reduced ion concentrations, improved mechanical properties, and extended service life of fuel cells by minimizing ion contamination and maintaining structural integrity.
Implementation Method 1
A special method for the mechanical consolidation of nonwovens is hydroentanglement, in which water is directed at an increased pressure of around 20 to over 400 bar through a large number of nozzles onto the fleece to be consolidated. The impulse force of the water jets leads to a mechanical anchoring of the fibers in the product.
Implementation Method 2
e) if used in step a). Fiber composition comprises precursors of carbon fibers, subjecting the nonwoven fabric to pyrolysis at a temperature of at least 1000 °C.
Implementation Method 3
d) optionally subjects the nonwoven obtained in step c) to a thermal and/or mechanical treatment for drying and/or further solidification
Data Source
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AI summary
The present invention relates to a method for producing a high-purity gas diffusion layer, the gas diffusion layer obtainable by this method, and a fuel cell containing such a gas diffusion layer. A fiber mat comprising carbon fibers and/or carbon fiber precursors is solidified into a nonwoven fabric by the action of water-containing fluid jets, wherein the water used has a conductivity of at most 250 microsiemens/cm at 25 degrees Celsius.