Microporous Gas Diffusion Electrode for Fuel Starvation Reversal
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Solution Overview
Problem
Fuel cells experience performance deterioration due to carbon corrosion in the anode gas diffusion electrode during cell reversal states caused by fuel starvation, leading to increased contact resistance and reduced durability.
Innovation Solution
A gas diffusion electrode is developed with a microporous layer containing carbon microparticles and a fluorinated resin with a fluoroalkyl chain, where the specific surface area of carbon microparticles and the content of fluorinated resin are optimized to inhibit carbon corrosion, as represented by the formula A-30×(C/B) = 10 to 50.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional microporous layer is used in the anode gas diffusion electrode, then gas diffusivity and water removability are maintained, but carbon corrosion occurs during cell reversal states leading to increased contact resistance and performance deterioration
Solution Approach 1:
The patent applies iridium oxide or ruthenium oxide to the anode gas diffusion electrode to convert the harmful carbon corrosion reaction into beneficial water electrolysis reaction during cell reversal states. The precious metal catalyst promotes reaction (3) which consumes water and generates electrons, thereby preventing carbon corrosion reaction (4) and eliminating the harmful effects of carbon loss and contact resistance increase.
Solution Approach 2:
The patent introduces iridium oxide or ruthenium oxide as an intermediary substance that mediates the electrochemical reactions during cell reversal. These precious metal materials act as catalysts that facilitate water electrolysis, serving as an intermediate pathway to generate electrons without requiring carbon consumption, thus protecting the carbon structure from corrosion.
2Reliability
If monitoring and control methods are used to avoid cell reversal states, then carbon corrosion can be prevented, but system cost increases
Solution Approach 1:
The patent applies iridium oxide or ruthenium oxide in advance to the anode gas diffusion electrode during manufacturing, creating a protective catalyst layer before the fuel cell operates. This preliminary action ensures that when cell reversal states occur, the protective catalyst is already in place to promote water electrolysis and prevent carbon corrosion, eliminating the need for complex real-time monitoring and control systems.
Solution Approach 2:
The patent enables the anode gas diffusion electrode to protect itself against carbon corrosion by incorporating precious metal catalysts that automatically activate during cell reversal states. The electrode material itself provides the protective function through the catalytic activity of iridium oxide or ruthenium oxide, making the system self-protecting without requiring external monitoring or control interventions.
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 proposed gas diffusion electrode effectively suppresses carbon degradation in cell reversal states, maintaining fuel cell performance and improving durability, especially during long-term operation.
Implementation Method 1
carbon corrosion in the anode gas diffusion electrode during cell reversal states
Implementation Method 2
high electrical conductivity for extracting generated electric current
Implementation Method 3
high gas diffusivity for allowing a gas supplied from the bipolar plates to be diffused into the catalyst layers
Implementation Method 4
high water removability for discharging water generated via the electrochemical reactions to the bipolar plates
Implementation Method 5
a part of the water generated on the cathode side permeates the electrolyte membrane and moves to the anode side
Implementation Method 6
an electromotive force is generated via electrochemical reactions occurring at both the electrodes
Implementation Method 7
carbon microparticles and a fluorinated resin having a fluoroalkyl chain, and when a specific surface area of the carbon microparticles is denoted by A (m2/g), a content of the carbon microparticles per unit volume in the microporous layer is denoted by B (g/cm3), and a content of the fluorinated resin having a fluoroalkyl chain per unit volume in the microporous layer is denoted by C (g/cm3), a value obtained by Formula X given below is 10 to 50
Data Source
AI summary
The present invention provides a gas diffusion electrode which is capable of restraining the progression of carbon corrosion at an anode gas diffusion electrode of a fuel cell even in a reverse potential state that is caused by deficiency of a fuel supplied to the anode gas diffusion electrode, and which is therefore free from a decrease in the power generation performance of the cell. This gas diffusion electrode includes a conductive porous base material that contains carbon fibers as a constituent material, and a microporous layer that is in contact with one surface of the conductive porous base material; and this gas diffusion electrode is characterized in that the microporous layer contains, as constituent materials, carbon fine particles and a fluororesin that has a fluoroalkyl chain, and if A (m2/g) is the specific surface area of the carbon fine particles, B (g/cm3) is the content of the carbon fine particles per unit volume in the microporous layer, and C (g/cm3) is the content of the fluororesin that has a fluoroalkyl chain per unit volume in the microporous layer, the value obtained by the formula X described below is 10 to 50. (Formula X): A−30×(C/B).