Gas Diffusion Electrode Substrate Anti-Plugging Design
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Solution Overview
Problem
Conventional gas diffusion electrode substrates for polymer electrolyte fuel cells face challenges in maintaining high performance at low temperatures due to issues like flooding and plugging, which are not adequately addressed by existing solutions that compromise either gas diffusivity or mechanical and electrical conductivity.
Innovation Solution
A gas diffusion electrode substrate with a microporous layer composed of a carbon-based filler and fluororesin on one surface, featuring a sliding angle of 30 degrees or less and through-plane gas permeation resistance between 15 to 190 mmAq, is developed, along with a production method involving a carbon coating solution applied to an electrode substrate with specific retention and drying conditions to enhance anti-flooding and anti-plugging characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a microporous layer is impregnated in the inside of the electrode substrate to improve hydrophobicity and prevent plugging, then liquid water is unlikely to stay in the flow channel, but the porosity inside the electrode substrate is reduced and gas diffusivity is decreased
Solution Approach 1:
The invention applies local quality by creating a microporous layer only on the bipolar plate side surface of the electrode substrate, rather than impregnating the entire substrate. This localized approach provides hydrophobicity where needed (at the flow channel interface) while preserving the bulk substrate's porosity and gas diffusivity.
Solution Approach 2:
The invention transitions from a three-dimensional impregnation approach to a two-dimensional surface coating approach. By forming the microporous layer as a surface coating rather than an internal impregnation, the solution prevents plugging at the critical interface without reducing the internal porosity needed for gas transport.
2Object-affected harmful factors
If FEP is used to cover the carbon fiber of the electrode substrate to improve hydrophobicity and prevent plugging, then liquid water is unlikely to stay in the flow channel, but the interface resistance between the bipolar plate and the gas diffusion electrode substrate is increased
Solution Approach 1:
The invention uses composite materials by combining carbon-based filler (providing conductivity and structural integrity) with fluororesin (providing hydrophobicity). This composite microporous layer achieves both low interface resistance and high hydrophobicity, unlike pure FEP coatings.
Solution Approach 2:
The invention changes the material composition parameters by using a composite of carbon-based filler and fluororesin rather than pure FEP. This compositional change maintains electrical conductivity while achieving the desired hydrophobicity for preventing plugging.
3Object-affected harmful factors
If a microporous layer comprising carbon black and fluororesin is formed on both sides of the electrode substrate to improve hydrophobicity and prevent plugging, then liquid water is unlikely to stay in the flow channel, but water removal from the electrode substrate to the bipolar plate is inhibited and flooding is remarkable
Solution Approach 1:
The invention applies local quality by forming the microporous layer only on the bipolar plate side surface, not on both sides. This localized application prevents plugging at the flow channel interface while allowing water to be removed effectively from the catalyst layer side, avoiding flooding.
Solution Approach 2:
The invention inverts the conventional approach of making the entire electrode substrate hydrophobic. By applying hydrophobicity only at the flow channel interface rather than throughout the substrate, the solution prevents plugging without interfering with water removal pathways.
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 substrate effectively prevents plugging, maintains high gas diffusivity, and exhibits excellent mechanical, electrical, and thermal conductivity, thereby supporting high fuel cell performance at low temperatures.
Implementation Method 1
the gas diffusion electrode substrate surface on the bipolar plate side is smooth and has high hydrophobicity, whereby liquid water is unlikely to stay in the flow channel
Implementation Method 2
the sliding angle of water on the surface on the opposite side of the surface on which the microporous layer is formed is 30 degrees or less
Implementation Method 3
high gas diffusivity for allowing a gas supplied from the bipolar plate to be diffused into the catalyst layer
Implementation Method 4
high electrical conductivity for extracting generated electric current
Implementation Method 5
excellent mechanical properties, electrical conductivity, and thermal conductivity
Data Source
AI summary
A gas diffusion electrode substrate that is used in a fuel cell, wherein a microporous layer constituted by a carbon based filler and a fluororesin is formed on one surface of the electrode substrate, the sliding angle of water on the surface on the opposite side of the surface on which the microporous layer is formed is 30 degrees or less, and the through-plane gas permeation resistance is 15 to 190 mmAq.