Water Control Sheet for Polymer Electrolyte Fuel Cells
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Solution Overview
Problem
Conventional water control sheets in polymer electrolyte fuel cells suffer from inadequate drainage and gas diffusion properties, leading to reduced fuel cell performance, especially under high moisture conditions, due to excessive fluororesin or carbon impregnation and brittle carbonized nanofibers that compromise handling and productivity.
Innovation Solution
A water control sheet composed of nonwoven fabric with conductive fibers containing conductive particles internally within a hydrophobic organic resin, which provides superior drainage and gas diffusion properties without the need for carbonization, allowing for improved handling and reduced costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional water control sheets are prepared by impregnating conductive porous substrate with fluororesin or carbon powder, then water control function is provided, but drainage and gas diffusion properties decrease due to excess impregnation
Solution Approach 1:
The invention uses a porous polymer electrolyte membrane as the water control sheet that inherently provides both water control and gas diffusion functions through its porous structure, eliminating the need for impregnation with fluororesin or carbon powder that would block pores and reduce drainage properties
Solution Approach 2:
The invention extracts and separates the water control function from the gas diffusion function by using a dedicated porous polymer electrolyte membrane for water control while maintaining the gas diffusion layer for its primary function, avoiding the compromise that occurs when both functions are combined in a single impregnated layer
2Strength
If carbonized nanofibers are used in water control sheets, then structural integrity is improved, but handling characteristics deteriorate due to brittleness
Solution Approach 1:
The invention changes the material parameter from carbonized nanofibers to a porous polymer electrolyte membrane material that inherently provides both structural integrity and flexibility, eliminating the brittleness issue while maintaining the required mechanical strength through the membrane's cross-linked polymer structure
3Shape
If water control layers are made dense by coating method, then shape retention is improved, but water and gas permeability in planar direction decreases
Solution Approach 1:
The invention uses a porous polymer electrolyte membrane that maintains a porous structure throughout its thickness, providing both shape retention through the membrane's inherent mechanical properties and high water and gas permeability through its controlled pore structure, avoiding the trade-off imposed by dense coating methods
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 enhances fuel cell performance by maintaining high power generation efficiency under high moisture conditions, preventing flooding, and offering superior handling characteristics and productivity, with reduced resistance and volume.
Implementation Method 1
each of the conductive fibers includes conductive particles and a hydrophobic organic resin
Implementation Method 2
each of the conductive fibers includes conductive particles and a hydrophobic organic resin
Implementation Method 3
a plurality of conductive fibers formed into a nonwoven fabric
Data Source
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AI summary
A water control sheet having superior drainage and gas diffusion properties and superior handling characteristics, and a gas diffusion sheet, a membrane-electrode assembly and a polymer electrolyte fuel cell, which utilize the water control sheet, are provided. The water control sheet is independent and located for use adjacent to a catalyst layer of a polymer electrolyte fuel cell, and is formed of a nonwoven fabric containing conductive fibers containing conductive particles at least inside a hydrophobic organic resin. The gas diffusion sheet, the membrane-electrode assembly and the polymer electrolyte fuel cell according to the present invention have the above water control sheet.