Gas Diffusion Electrode Fiber Protrusion Mitigation
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Solution Overview
Problem
Existing gas diffusion electrodes for fuel cells are prone to short circuit currents due to protruding carbon fibers, which penetrate the polymer electrolyte membrane, leading to reduced durability and performance, especially with repeated swelling and shrinking during fuel cell operation.
Innovation Solution
A gas diffusion electrode with a porous carbon electrode substrate bonded by resin carbide, featuring a microporous layer with specific thickness and structure, designed to prevent carbon fiber protrusions and enhance mechanical strength and flexibility, thereby reducing the occurrence of short circuit currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous carbon electrode substrate is used in a fuel cell, then gas diffusion and electrochemical reaction are enabled, but carbon fiber protrusions penetrate the polymer electrolyte membrane causing short circuit currents and reduced durability
Solution Approach 1:
The invention extracts and removes protruding carbon fibers from the surface of the porous carbon electrode substrate before assembling the fuel cell. This is achieved through mechanical methods such as brushing or blowing air to detach and remove the protrusions, thereby eliminating the source of short circuit currents and improving fuel cell reliability
Solution Approach 2:
The invention performs preliminary treatment of the porous carbon electrode substrate by removing protruding carbon fibers before the fuel cell assembly is completed. This preliminary action prevents the formation of short circuit currents during fuel cell operation, addressing the reliability issue before it can manifest
2Strength
If the porous carbon electrode substrate is compressed during fuel cell assembly, then good contact with the membrane electrode assembly is achieved, but new carbon fiber protrusions are generated that can penetrate the membrane
Solution Approach 1:
The invention applies preliminary removal treatment for carbon fiber protrusions before the compression step. By removing protruding fibers in advance through brushing or air blowing, the invention prevents these fibers from being further compressed or generating new protrusions during the assembly compression process
Solution Approach 2:
The invention applies preliminary anti-action by removing carbon fiber protrusions before compression. This counteracts the potential harmful effect of compression that would otherwise generate or exacerbate fiber protrusions, thereby preventing short circuit currents while maintaining necessary contact pressure
3Ease of manufacture
If carbon short fibers are not sufficiently removed from the substrate surface, then manufacturing is simpler, but short circuit currents occur due to fiber penetration
Solution Approach 1:
The invention extracts carbon short fibers from the substrate surface using simple mechanical methods such as brushing or air blowing. These methods are easy to implement and do not require complex processing equipment, maintaining ease of manufacture while effectively removing fibers that would cause short circuit currents and improving fuel cell reliability
Data Source
AI summary
A gas diffusion electrode includes a porous carbon electrode substrate and a microporous layer(s) provided at least on one surface of the porous carbon electrode substrate. The porous carbon electrode substrate is composed of carbon short fibers bonded with a resin carbide. When the region of the porous carbon electrode substrate, extending from a plane that has a 50% filling rate and is closest to one surface of the substrate to a plane that has the 50% filling rate and is closest to the other surface thereof, is trisected in the through-plane direction to obtain three layers, a layer located closer to one surface has a layer filling rate different from the layer filling rate of the layer located closer to the other surface. The microporous layer has a thickness under an added pressure of 0.15 MPa of from 28 to 45 μm, and has a thickness under an added pressure of 2 MPa of from 25 to 35 μm.