Fuel Cell Catalyst Layer Pore Size Gradient
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Solution Overview
Problem
The random formation of voids in catalyst layers with fibrous electric conductors leads to non-uniform gas pathways, hindering efficient gas diffusion and electrochemical reactions in fuel cells.
Innovation Solution
A membrane electrode assembly (MEA) is designed with catalyst layers containing fibrous electric conductors, catalyst particles, and proton-conductive resin, where the pore diameters in two distinct regions (within 200 nm and beyond 200 nm of the fibrous conductor) differ, allowing for enhanced gas diffusion and proton transport by creating uniform gas pathways.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a plate-like carbon member is added to the catalyst layer to form voids, then gas diffusion performance is improved, but the voids are formed randomly causing non-uniform gas pathways
Solution Approach 1:
The patent uses a fibrous electric conductor with controlled pore structure in the catalyst layer. The fibrous material creates a porous network that provides uniform gas pathways while maintaining electrical conductivity. The pores are distributed homogeneously throughout the catalyst layer, ensuring consistent gas diffusion performance across the entire layer.
Solution Approach 2:
The patent creates a composite catalyst layer by combining fibrous electric conductor material with catalyst particles. This composite structure integrates the gas diffusion benefits of porous fibrous materials with the catalytic activity of metal particles, achieving both uniform gas pathways and high catalytic performance in a single layer.
2Productivity
If a fibrous electric conductor is added to the catalyst layer, then gas diffusion performance is improved, but the pore distribution becomes non-uniform
Solution Approach 1:
The patent applies local quality by creating different pore size regions within the catalyst layer. The fibrous electric conductor structure provides smaller pores in certain regions while maintaining overall uniform distribution, allowing optimized gas diffusion pathways at different locations within the catalyst layer.
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 improves gas diffusion and proton transport performance, enabling more efficient oxidation or reduction reactions in the catalyst layer, thereby enhancing the overall performance of the fuel cell.
Implementation Method 1
Gas supplied to the gas diffusion layer from the separator diffuses in the diffusion layer, and is oxidized or reduced in the catalyst layer. Increasing gas diffusion performance in the catalyst layer can improve the efficiency of the electrochemical reaction.
Implementation Method 2
The at least one catalyst layer contains a fibrous electric conductor, catalyst particles, a particulate electric conductor, and a proton-conductive resin.
Data Source
AI summary
A membrane electrode assembly includes an electrolyte membrane, and a pair of electrode layers which sandwich the electrolyte membrane. The pair of electrode layers include a pair of catalyst layers which sandwich the electrolyte membrane, and a pair of gas diffusion layers disposed on the pair of catalyst layers on opposite sides to the electrolyte membrane. At least one catalyst layer contains a fibrous electric conductor, catalyst particles, a particulate electric conductor, and a proton-conductive resin. The at least one catalyst layer has a first region at a distance of 200 nm or less from the fibrous electric conductor, and a second region at a distance of more than 200 nm from the fibrous electric conductor. Pores are present in the first and second regions. A mode diameter M1 of the pores in the first region and a mode diameter M2 of the pores in the second region satisfy M1<M2.