Fuel Cell Gas Diffusion Electrode Substrate Pore Distribution
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Solution Overview
Problem
Current gas diffusion electrode substrates for fuel cells face challenges in maintaining high performance across a wide temperature range due to issues like flooding at low temperatures and dry-out at high temperatures, while also compromising mechanical, electrical, and thermal conductivity.
Innovation Solution
A gas diffusion electrode substrate with a microporous part on one surface and a specific pore size distribution, where pores between 0.1 μm and 10 μm are increased to enhance water removal, and pores between 10 μm and 100 μm provide gas diffusion, maintaining anti-flooding and anti-dry-out characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If microporous part is impregnated in electrode substrate to improve gas diffusivity and water removal performance, then fuel cell performance is improved in low humidity condition, but high gas diffusivity and high water removal performance cannot be simultaneously satisfied, particularly fuel cell performance is insufficient at low temperatures
Solution Approach 1:
The invention applies local quality by creating a microporous part with specific pore size distribution (0.03-3 μm) on the surface of the electrode substrate, while the interior maintains larger pores (10-100 μm). This localized differentiation allows the surface to excel at water removal through capillary action while the interior provides gas diffusion pathways, resolving the contradiction between water removal performance and gas diffusivity across different temperature conditions.
Solution Approach 2:
The invention utilizes porous materials with specifically controlled pore size distribution. The microporous part contains pores of 0.03-3 μm for effective water removal, while the electrode substrate interior contains pores of 10-100 μm for gas diffusion. This multi-scale porous structure enables simultaneous optimization of both water removal and gas diffusion functions that were previously mutually exclusive.
2Speed
If large quantity of pore-forming particles are put into microporous layer to form through holes, then gas diffusivity is improved, but water discharged in microporous layer accumulates in carbon paper and inhibits diffusion of gas
Solution Approach 1:
The invention segments the pore structure into two distinct zones: a microporous part (0.03-3 μm) for water removal and an interior porous structure (10-100 μm) for gas diffusion. This segmentation prevents water accumulation by providing dedicated microporous pathways that efficiently transport water away from the gas diffusion regions, eliminating the harmful effect of water blocking gas diffusion pathways.
Solution Approach 2:
The microporous part acts as an intermediary between the catalyst layer and the electrode substrate interior. It receives water from the catalyst layer through capillary action in its fine pores (0.03-3 μm) and facilitates its removal, while simultaneously allowing gas to pass through to the larger pores (10-100 μm) in the interior. This intermediary structure mediates between water removal and gas diffusion functions, preventing water accumulation that would otherwise block gas diffusion.
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 achieves excellent gas diffusivity and water removal performance across a wide temperature range, ensuring high fuel cell performance with improved mechanical, electrical, and thermal conductivity.
Implementation Method 1
a microporous part (A) is formed on one surface of the electrode substrate with a thickness in the range of 10 μm or more and 60 μm or less, and in the gas diffusion electrode substrate, the pore volume of pores with a pore size of 0.1 μm or more and less than 10 μm is within the range of 0.9 times or more and 5 times or less of the pore volume of pores with a pore size of 10 μm or more and less than 100 μm
Implementation Method 2
The gas diffusion electrode substrate is required to have high gas diffusivity for allowing a gas supplied from the bipolar plate to be diffused into the catalyst layer
Data Source
AI summary
A gas diffusion electrode substrate that is used in a fuel cell and is constituted by an electrode substrate and microporous parts, in which a microporous part (A) is formed on one surface of the electrode substrate with a thickness in the range of 10 μm or more and 60 μm or less, and in the gas diffusion electrode substrate, the pore volume of pores with a pore size of 0.1 μm or more and less than 10 μm is within the range of 0.9 times or more and 5 times or less of the pore volume of pores with a pore size of 10 μm or more and less than 100 μm.