Gas Diffusion Electrode Organic Substance Control
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Solution Overview
Problem
Polymer electrolyte fuel cells face degradation issues due to organic substances entering during storage and operation, leading to reduced performance and durability, especially during repeated startups and shutdowns.
Innovation Solution
A method for producing gas diffusion electrodes and polymer electrolyte fuel cells involves forming catalyst layers with a specific mixture containing a carbon powder, cation exchange resin, and an alcohol with a vapor pressure of 0.6 to 12.3 kPa, where the organic substance content is adjusted to meet specific mass ratios to minimize residual organic substances, ensuring the catalyst layer's integrity and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If organic substances are used in catalyst layer formation, then the catalyst layer can be formed with proper binding and structure, but organic substances remain in the catalyst layer causing catalyst poisoning and performance degradation
Solution Approach 1:
The patent applies preliminary action by performing vacuum drying or heating treatment before the fuel cell operation to remove organic substances from the catalyst layer. This preliminary removal prevents catalyst poisoning and performance degradation that would occur during operation, ensuring the catalyst layer is clean before fuel gas supply begins.
Solution Approach 2:
The patent converts the harmful presence of organic substances (used as binders in catalyst layer formation) into a beneficial situation by implementing a drying/heating step that removes these substances before they can cause harm. The organic substances serve their purpose during formation, then are systematically removed to eliminate their harmful effects during operation.
2Duration of action of stationary object
If the fuel cell is stored after shutdown, then the fuel cell structure is preserved, but organic substances enter the catalyst layer from the outside causing performance degradation
Solution Approach 1:
The patent applies the inert atmosphere principle by storing the fuel cell in a nitrogen atmosphere after shutdown. The nitrogen gas creates an inert environment that prevents organic substances from entering the catalyst layer, thereby preventing catalyst poisoning and performance degradation during storage while maintaining the fuel cell structure.
Solution Approach 2:
The patent performs preliminary action by supplying nitrogen gas to the fuel cell before storage to displace air and create an inert atmosphere. This preliminary step ensures that during subsequent storage, organic substances cannot enter the catalyst layer, preventing contamination while the fuel cell remains stationary.
3Reliability
If water is filled in gas channels before shutdown, then fuel or oxidant gas leakage is prevented, but organic substances can still enter and poison the catalyst
Solution Approach 1:
The patent applies inert atmosphere by using nitrogen gas instead of water to fill the gas channels before shutdown and storage. The nitrogen atmosphere prevents both gas leakage and organic substance contamination, overcoming the limitation of water filling which only prevents leakage but not contamination.
Solution Approach 2:
The patent uses nitrogen gas as an intermediary substance that performs dual functions: preventing gas leakage (like water) and preventing organic substance entry (unlike water). The nitrogen atmosphere acts as a protective mediator between the catalyst layer and external organic contaminants during storage.
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 approach results in fuel cells with excellent durability and initial performance, preventing degradation even after long-term use and repeated startups, by effectively reducing the impact of organic substances on the electrode catalyst.
Implementation Method 1
a liquid containing an alcohol capable of dissolving or dispersing the cation exchange resin and having a vapor pressure at 20° C. of 0.6 to 12.3 kPa
Implementation Method 2
having a vapor pressure at 20° C. of 0.6 to 12.3 kPa
Data Source
AI summary
The present invention provides a gas diffusion electrode capable of sufficiently preventing not only degradation of MEA during storage but also degradation of initial characteristics and durability during the time period from production to initial use, and a polymer electrolyte fuel cell including the gas diffusion electrode. The gas diffusion electrode includes a catalyst layer in which A1 representing a total mass of organic substance comprising alcohol, a partial oxide of the alcohol, a product of intramolecular dehydrogenation reaction of the alcohol, a product of intermolecular condensation reaction of the alcohol, a product of intermolecular condensation reaction between the alcohol and the partial oxide and a product of intermolecular condensation reaction of the partial oxide, E1 representing a total mass of carbon powder and G1 representing a total mass of cation exchange resin are controlled to satisfy {100×A1/(E1+G1)}≦0.05.