Polymer Electrolyte Membrane for Fuel Cells with Swelling Resistance
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Solution Overview
Problem
Conventional polymer electrolyte fuel cells face challenges in achieving high power generation performance and durability due to the trade-off between low electrical resistance and mechanical strength, as increasing the proportion of sulfonic acid groups in the polymer membrane leads to excessive water swelling and potential cracking.
Innovation Solution
A polymer with a specific composition comprising repeating units represented by formulas (U1) and (U2), which provides a balance of low electrical resistance, high softening temperature, and flexibility, allowing for stable operation through the inclusion of tetrafluoroethylene units and controlled equivalent weight, thereby enhancing mechanical strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the proportion of sulfonic acid groups in the polymer membrane is increased to reduce electrical resistance, then power generation performance is improved, but the polymer becomes excessively swollen with water and mechanical strength becomes insufficient
Solution Approach 1:
The patent changes the chemical structure parameters of the polymer by introducing perfluoroalkylene groups with etheric oxygen atoms and controlling the ratio of different repeating units. This modifies the polymer's physical properties to achieve lower electrical resistance while maintaining mechanical strength and reducing excessive water swelling.
Solution Approach 2:
The patent creates a composite polymer structure combining multiple types of repeating units (U1) and (U2) with specific functional groups. This composite structure allows the membrane to simultaneously achieve low electrical resistance for high power generation performance and sufficient mechanical strength for durability.
2Reliability
If the proportion of sulfonic acid groups is increased to reduce equivalent weight, then electrical resistance is reduced, but molecular weight becomes insufficient and mechanical strength deteriorates
Solution Approach 1:
The patent changes the molecular structure parameters by introducing perfluoroalkylene groups and controlling the composition of repeating units, which allows achieving low equivalent weight for low electrical resistance while maintaining sufficient molecular weight for mechanical strength.
3Adaptability or versatility
If the polymer membrane undergoes repeats of swelling in wet state and shrinkage in dry state, then operational flexibility is maintained, but the membrane is likely to be cracked and damaged
Solution Approach 1:
The patent modifies the polymer's physical parameters through the introduction of perfluoroalkylene groups with etheric oxygen atoms, which changes the membrane's swelling-shrinking behavior to be more reversible and less damaging, thereby improving durability while maintaining operational flexibility.
Solution Approach 2:
The patent provides beforehand cushioning against crack formation by designing a polymer structure that can accommodate swelling and shrinking stresses. The perfluoroalkylene groups act as cushioning elements that absorb mechanical stress during repeated wet-dry cycles.
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 polymer electrolyte membrane exhibits improved power generation performance at higher temperatures and increased durability, maintaining mechanical strength while reducing electrical resistance, and is less prone to damage from repeated swelling and shrinkage cycles.
Implementation Method 1
a polymer electrolyte membrane disposed between the anode and the cathode
Implementation Method 2
the polymer electrolyte membrane undergoes repeats of swelling in a wet state and shrinkage in a dry state
Data Source
AI summary
A polymer electrolyte membrane made of a polymer has a low electrical resistance, high heat resistance and is strong against repeats of swelling and shrinkage. Thus, a membrane/electrode assembly for polymer electrolyte fuel cells having high power generation performance and excellent in durability can be provided.For a polymer electrolyte membrane 15 or for a catalyst layer 11 constituting electrodes 13 and 14, a polymer comprising units (U1) and units (U2) is used:Q1, Q2: a perfluoroalkylene group which may have —O— or the like; Rf1, Rf2: a perfluoroalkyl group which may have —O—; X: an oxygen atom or the like; a: 0 or the like; Y, Z: a fluorine atom, or a monovalent perfluoroorganic group such as —CF3; S: 0 to 1; and t: 0 to 3.