Gas Diffusion Layer Moisture Vapor Transmission Control
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Solution Overview
Problem
Current gas diffusion layer (GDL) materials for solid polymer fuel cells are inadequate in maintaining optimal humidity levels across varying relative humidity (RH) conditions and high/low gas flow rates, leading to issues such as dry-up and flooding, which affect fuel cell performance and longevity.
Innovation Solution
A gas diffusion layer member with a sheet-shaped, conductive base material of specific thickness and density, incorporating a microporous layer with a conductive carbon powder and polytetrafluoroethylene, achieving a moisture vapor transmission rate of 1300 to 2000 g/m²/h, which balances RH characteristics and enhances power generation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gas diffusion layer materials are used, then the fuel cell can operate, but the material cannot maintain optimal humidity levels across varying RH conditions and gas flow rates, leading to dry-up and flooding issues
Solution Approach 1:
The patent applies parameter changes by precisely controlling the moisture vapor transmission rate (MVTR) of the gas diffusion layer material to fall within the range of 1000 to 2000 g/m²/day. This parameter optimization enables the material to maintain appropriate humidity levels across varying relative humidity conditions and gas flow rates, preventing both dry-up and flooding issues while enhancing reliability and adaptability simultaneously.
Solution Approach 2:
The patent employs composite materials by formulating the gas diffusion layer with a specific composition including polytetrafluoroethylene (PTFE) as a binder and carbon black as a conductive filler. This composite structure, where PTFE provides hydrophobicity and controlled moisture transmission while carbon black ensures electrical conductivity, enables the material to adapt to varying operating conditions without compromising humidity maintenance or performance reliability.
2Productivity
If the gas diffusion layer material has high porosity to improve gas transmission, then gas flow is enhanced, but the material loses dimensional stability and becomes difficult to handle in production
Solution Approach 1:
The patent applies local quality by creating a gas diffusion layer with non-uniform PTFE distribution and controlled pore structure. The material has regions with different densities and porosity levels, allowing high gas transmission in functional areas while maintaining sufficient dimensional stability in structural regions. This local variation enables both high productivity through efficient gas transport and ease of operation through improved handling characteristics.
3Weight of moving object
If the gas diffusion layer material is made thinner to reduce weight and stack size, then weight and compactness are improved, but the material loses its ability to effectively manage water and maintain humidity
Solution Approach 1:
The patent applies porous materials by utilizing the inherent porosity of the gas diffusion layer structure combined with controlled PTFE content. The porous network provides capillary channels for water transport while the hydrophobic PTFE regions regulate moisture vapor transmission. This porous architecture enables thin-film designs that maintain effective water management and humidity control capabilities while reducing overall weight and enabling more compact fuel cell stacks.
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 solution maintains superior power generating performance under both high and low RH conditions, preventing dry-up and flooding, and facilitates easier handling and automation in fuel cell production due to improved dimensional stability and water management.
Implementation Method 1
a humidity adjusting film including a conductive carbon powder and polytetrafluoroethylene, characterized in that the gas diffusion layer member has a moisture vapor transmission rate by the measurement method defined in JIS (Japan Industrial Standard) L 1099:2006 of 1300 to 2000 g/m²/h
Implementation Method 2
The polymer electrolyte membrane 10 requires accompanying H2O to conduct protons
Implementation Method 3
The H2O which was supplied for humidifying the fuel gas 50 dissolves in the electrolyte in the anode layer 20 and the polymer electrolyte membrane 10 and travels to the cathode side together with movement of the protons
Implementation Method 4
Fuel gas (H2 etc.) which is introduced from the channel 50 passes through the first carbon fiber current collector layer (anode side carbon fiber current collector layer) 40 and reaches the first catalyst layer (anode and fuel electrode) 20. Here, the fuel gas releases electrons while generating protons (H+)
Data Source
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AI summary
To provide a gas diffusion layer member with a good RH balance. A gas diffusion layer member for solid polymer type fuel cell use comprising a sheet-shaped gas permeable conductive base material of a thickness of 100 to 250 µm in range, which gas diffusion layer member is characterized in that a moisture vapor transmission rate by the measurement method defined by JIS L 1099:2006 is 1300 to 2000 g/m2/h in range.