Gas Diffusion Layer Pore Thickness Ratio
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Solution Overview
Problem
The use of a grooved fluid flow passage in fuel cell separators leads to poor contact between gas diffusion layers and separators, resulting in increased contact resistance and deteriorated gas diffusivity, which can be mitigated by thickening the gas diffusion layers but at the cost of power generation performance.
Innovation Solution
A gas diffusion layer with a diffusion layer substrate having a pore diameter to thickness ratio of 0.35 or more, incorporating conductive carbon fibers at a content rate of 30% or more, to maintain thickness and increase pore diameter, reducing contact resistance and enhancing diffusivity while securing mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gas diffusion layer is thickened to improve contact with the separator, then contact resistance is reduced, but gas diffusivity deteriorates
Solution Approach 1:
The invention changes the pore diameter to thickness ratio parameter to 0.35 or more, which simultaneously improves contact resistance and maintains gas diffusivity. This parameter optimization allows the gas diffusion layer to achieve both good separator contact and sufficient gas transport capability without requiring increased thickness.
Solution Approach 2:
The invention uses a composite structure combining a base layer and a porous layer with specific pore diameter to thickness ratio. This composite configuration allows the porous layer to provide excellent contact with the separator while the overall structure maintains high gas diffusivity, resolving the contradiction between contact resistance and gas transport.
2Productivity
If the gas diffusion layer is thinned to improve gas diffusivity, then gas transport is enhanced, but contact with the separator deteriorates
Solution Approach 1:
By optimizing the pore diameter to thickness ratio to 0.35 or more, the invention enables thin gas diffusion layers to maintain both excellent gas diffusivity and good separator contact. The increased pore diameter compensates for the reduced thickness, ensuring sufficient contact pressure and area while preserving gas transport pathways.
3Productivity
If the pore diameter is increased to improve gas diffusivity, then gas transport is enhanced, but mechanical strength deteriorates
Solution Approach 1:
The invention employs a composite structure with a base layer providing mechanical strength and a porous layer with optimized pore diameter to thickness ratio providing gas diffusivity. This composite configuration allows large pores for gas transport while the base layer maintains structural integrity and mechanical strength.
Solution Approach 2:
The invention applies different structural qualities to different regions: the porous layer has large pores for gas transport, while the base layer has a denser structure for mechanical support. This local differentiation allows the system to achieve both high gas diffusivity and sufficient mechanical strength simultaneously.
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
This configuration reduces contact resistance and maintains gas diffusivity, thereby improving power generation performance and mechanical strength of the fuel cell, while avoiding the deterioration of power generation performance associated with thickened gas diffusion layers.
Implementation Method 1
the diffusion layer substrate may include a conductive carbon fiber
Implementation Method 2
a diffusion layer substrate that has a ratio of a pore diameter to a thickness of 0.35 or more
Data Source
AI summary
To provide a gas diffusion layer that allows reducing an increase in contact resistance with a separator and also allows reducing deterioration of gas diffusivity. The gas diffusion layer is disposed in contact with a separator including a grooved fluid flow passage. The gas diffusion layer includes a diffusion layer substrate and a water-repellent layer. The diffusion layer substrate has a ratio of a pore diameter to a thickness of 0.35 or more. The water-repellent layer is disposed on a surface of the diffusion layer substrate. The diffusion layer substrate is made of a carbon fiber. A content rate of the carbon fiber is 30% or more.