Gas Diffusion Electrode Water-Repellent Layer Design
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Solution Overview
Problem
Conductive porous base materials used in gas diffusion electrodes lack inherent water repellency, leading to water leakage issues, especially in large-area electrodes immersed in electrolytic solutions, and require high-energy sintering processes for fluorine resins, which are prone to cracking and have low flexibility.
Innovation Solution
A gas diffusion electrode with a water-repellent layer composed of woven or non-woven fabrics made from hydrophobic materials, such as fluorine-based polymers, is used, which is bonded to a gas diffusion layer and includes a catalyst layer, providing improved water resistance and permeability without the need for high-temperature sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a water-repellent layer including fluorine resin such as PTFE is formed on the conductive porous base material, then water resistance is improved, but the layer is likely to have cracks and pinholes leading to water leakage
Solution Approach 1:
The patent uses a flexible polymer coating layer that forms a continuous film over the water-repellent layer, preventing cracks and pinholes from causing water leakage. This flexible film accommodates structural variations in the underlying layers while maintaining water tightness.
Solution Approach 2:
The patent creates a composite structure combining a water-repellent layer (with fluorine resin or hydrophobic treatment) and a flexible polymer coating layer. This composite approach leverages the water repellency of the first layer while the second layer provides crack prevention and structural integrity.
2Reliability
If high level of uniformity and condition control for drying and sintering processes is implemented, then water leakage is prevented, but manufacturing complexity and energy cost increase
Solution Approach 1:
The patent changes the material parameters by using a flexible polymer coating that cures at lower temperatures compared to sintering fluorine resin. This reduces the thermal processing requirements and simplifies manufacturing control while maintaining water tightness.
Solution Approach 2:
The flexible polymer coating layer acts as a sacrificial or sealant layer that can be applied as a thin coating and cured relatively simply. This layer compensates for imperfections in the underlying structure without requiring expensive or complex processing.
3Reliability
If fluorine resin such as PTFE is sintered at high temperature to enhance uniformity, then water resistance is improved, but energy cost increases
Solution Approach 1:
The patent changes the curing temperature parameter by using a flexible polymer coating that cures at lower temperatures. This alternative material system achieves the necessary uniformity and water tightness without requiring high-temperature sintering, thereby reducing energy consumption.
Solution Approach 2:
The patent substitutes the thermal sintering process (mechanical/thermal system) with a chemical curing process of a flexible polymer coating. This replacement reduces the temperature requirement and associated energy costs while achieving the desired functional outcome.
4Reliability
If the water-repellent layer is made with rigid structure, then water resistance is improved, but flexibility is reduced leading to warping and cracks
Solution Approach 1:
The patent employs a flexible polymer coating layer that maintains water tightness while accommodating warping and deformation of the electrode. This flexible film conforms to the underlying structure's shape changes without cracking, preserving both flexibility and water resistance.
Solution Approach 2:
The patent creates a composite where a flexible polymer coating is applied over the water-repellent layer. This combination allows the rigid or semi-rigid water-repellent layer to provide water resistance while the flexible outer layer accommodates structural changes and prevents cracking.
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 solution ensures uniform high water resistance and gas permeability, reducing the likelihood of water leakage and energy costs, while maintaining flexibility to prevent cracking, thus enhancing the performance and manufacturing efficiency of gas diffusion electrodes in electrochemical devices and fuel cells.
Implementation Method 1
a water-repellent layer consisting of a woven fabric or a non-woven fabric, and having water repellency, the woven fabric and the non-woven fabric each consisting of a fibrous material that is a hydrophobic material
Implementation Method 2
a gas diffusion layer stacked on and bonded to the water-repellent layer
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
A gas diffusion electrode includes: a water-repellent layer (31) which includes a woven fabric or a non-woven fabric, and which has water repellency; a gas diffusion layer (33) which is stacked on the water-repellent layer (31); and a catalyst layer (34) which is disposed opposite the water-repellent layer (31) relative to the gas diffusion layer (33).