Fuel Cell Gas Diffusion Layer Rigidity and Conductivity
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Solution Overview
Problem
Conventional gas diffusion layers in polymer electrolyte fuel cells face challenges with rigidity, adhesiveness, gas permeability, water permeability, and electron conductivity, leading to issues like flooding and micro short-circuits, particularly when using carbon paper or carbon cloth/felt substrates.
Innovation Solution
A method involving impregnating conductive carbon fiber cloth or felt with a thermoplastic fluorocarbon resin and baking it to enhance rigidity, followed by applying a shearing force to a dispersion containing conductive carbon particles and another fluorocarbon resin to form a water repellent layer, ensuring optimal adhesiveness and conductivity without inhibiting gas diffusibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon paper or carbon cloth/felt is used as conductive porous substrate, then electron conductivity is improved, but rigidity deteriorates leading to handling difficulties and potential flooding
Solution Approach 1:
The patent uses a composite structure combining carbon fiber cloth/felt substrate with fluorocarbon resin coating. The carbon fiber provides electron conductivity while the fluorocarbon resin layer provides rigidity and water repellency, creating a composite material that achieves both electrical performance and structural stability without flooding issues
Solution Approach 2:
The patent modifies the physical and chemical parameters of the carbon fiber substrate by impregnating it with fluorocarbon resin and controlling the baking temperature and duration. This changes the rigidity parameter from too flexible to optimal, while maintaining electron conductivity through proper resin selection and processing conditions
2Reliability
If water repellent treatment is applied to improve water permeability, then flooding is prevented, but adhesiveness deteriorates leading to layer separation
Solution Approach 1:
The patent applies water repellent treatment locally and selectively to specific regions of the gas diffusion layer rather than uniformly throughout. This localized treatment maintains water permeability in critical areas while preserving adhesiveness in other regions, preventing both flooding and layer separation
Solution Approach 2:
The patent utilizes the porous structure of the carbon fiber substrate and fluorocarbon resin coating to achieve water repellency through capillary action control. The porous material allows water vapor transmission while repelling liquid water, maintaining both water permeability and structural adhesiveness
3Ease of operation
If carbon paper is used to maintain rigidity, then handling is improved, but mass productivity deteriorates due to excessive rigidity and processing difficulties
Solution Approach 1:
The patent optimizes the rigidity parameter of the carbon fiber substrate by controlling the fluorocarbon resin content, molecular weight, and baking conditions. This creates a substrate with moderate rigidity that is easy to handle during assembly but flexible enough to allow high-speed automated processing and stacking for mass production
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 approach results in a gas diffusion layer with improved rigidity, adhesiveness, gas permeability, and electron conductivity, reducing the likelihood of flooding and micro short-circuits, while maintaining ease of handling and high mass productivity.
Implementation Method 1
baking it to enhance rigidity
Implementation Method 2
impregnating a conductive porous substrate made of conductive carbon fiber cloth or conductive carbon fiber felt with a first dispersion containing a first fluorocarbon resin having thermoplasticity
Implementation Method 3
treating for water repellency
Implementation Method 4
applying a shearing force to a dispersion containing conductive carbon particles and another fluorocarbon resin
Implementation Method 5
to diffuse a reaction gas such as a fuel gas or an oxidant gas so as to uniformly supply the reaction gas from the gas channels 117 formed outside the gas diffusion layer 113 to the catalyst in the catalyst layer 112
Implementation Method 6
to rapidly carry away water produced by the reaction in the catalyst layer 112 to the gas channels 117 to prevent water clogging (flooding)
Implementation Method 7
to transfer the electrons necessary for the reaction and the produced electrons
Data Source
AI summary
The present invention provides a gas diffusion layer for a fuel cell which has proper rigidity, is easy to handle and contributes to the improvement of the productivity of fuel cells. A method for producing a gas diffusion layer for a fuel cell including a first step of: impregnating a conductive porous substrate made of a conductive carbon fiber cloth or conductive carbon fiber felt with a first dispersion containing a first fluorocarbon resin having thermoplasticity; and baking the first conductive porous substrate at a first baking temperature of not less than the melting point of the first fluorocarbon resin and less than the decomposition temperature of the first fluorocarbon resin to enhance the rigidity of the conductive porous substrate.