Gas Diffusion Electrode Microporous Layer Water Management
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Solution Overview
Problem
Conventional techniques fail to simultaneously achieve both flooding resistance and dry-out resistance in fuel cells, especially in high-power applications like fuel cell vehicles, across a wide temperature range.
Innovation Solution
A gas diffusion electrode with a microporous layer on an electrically conductive porous substrate, featuring a dense layer with a thickness of 1 µm or more and an average number density of pores between 0.15 µm and 1 µm, enhancing both gas diffusibility and water removal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydrophobic treatment is applied to the electrically conductive porous substrate to improve water removal performance, then flooding resistance is improved, but the substrate has coarse fibers that cause water vapor to condense into large water droplets, leading to flooding
Solution Approach 1:
The patent applies a microporous layer with controlled pore sizes (0.03-10 μm) on the hydrophobic substrate. This porous structure allows water vapor to diffuse through the layer and be removed efficiently, preventing flooding while maintaining the hydrophobic properties of the substrate for water droplet removal.
Solution Approach 2:
The gas diffusion electrode is constructed as a composite structure combining a hydrophobic electrically conductive porous substrate with a microporous layer containing hydrophobic agents (PTFE, FEP, etc.). This composite structure integrates the water droplet removal capability of the hydrophobic substrate with the vapor diffusion capability of the microporous layer, resolving the contradiction between handling liquid water and water vapor.
2Power
If the electrolyte membrane is operated at high temperature to improve power generation performance, then energy efficiency is improved, but the electrolyte membrane dries out, reducing ion conductivity and deteriorating power generation performance
Solution Approach 1:
The patent modifies the pore size distribution and hydrophobicity parameters of the gas diffusion electrode to optimize water management across different temperature conditions. The microporous layer with specific pore sizes (0.03-10 μm) and controlled hydrophobic agent content allows the electrode to maintain appropriate moisture levels in the electrolyte membrane whether operating at high or low temperatures, preventing both dry-out and flooding conditions.
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 provides a fuel cell with both dry-out resistance and flooding resistance, ensuring excellent power generation performance across a wide temperature range.
Implementation Method 1
a gas diffusion electrode including a microporous layer on at least one surface of an electrically conductive porous substrate... enhancing both gas diffusibility
Implementation Method 2
hydrophobicity is normally improved using a gas diffusion electrode substrate with an electrically conductive porous substrate subjected to a hydrophobic treatment
Implementation Method 3
When at a low temperature, the water vapor is condensed into water droplets, so that pores of the gas diffusion electrode are closed
Data Source
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AI summary
The purpose of the present invention is to provide a gas diffusion electrode having excellent dry-up resistance and flooding resistance, the gas diffusion electrode also having excellent power generation performance across a wide temperature range. In order to achieve this purpose, the present invention is configured as described below. Specifically, the present invention is a gas diffusion electrode having a microporous layer on at least one surface of an electroconductive porous substrate, wherein: the microporous layer has a first microporous layer in contact with the electroconductive porous substrate, and a dense layer in contact with the first microporous layer; the thickness of the dense layer is at least 1 µm; and the average number density B of pores having a pore diameter of 0.15-1 µm in the dense layer is at least 1.3A, where A is the average number density of pores having a pore diameter of 0.15-1 µm in the microporous layer disposed on at least one surface of the electroconductive porous substrate,.