Perfluorinated Polymer Electrolyte Membrane for Solid Fuel Cells
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Solution Overview
Problem
Conventional polymer electrolyte fuel cells face challenges in achieving high power generation performance with low electrical resistance while maintaining mechanical strength and durability, as increasing the proportion of sulfonic acid groups in the polymer membrane leads to excessive swelling and potential cracking due to repeated wet and dry states.
Innovation Solution
A polymer comprising specific repeating units with perfluoroalkylene and perfluoroalkyl groups, combined with tetrafluoroethylene units, is developed to achieve low electrical resistance, high softening temperature, and flexibility, resulting in a membrane/electrode assembly with enhanced heat resistance 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 and perfluoroalkyl groups with specific chain lengths and configurations. This modifies the polymer's physical properties including swelling behavior and mechanical strength while maintaining low electrical resistance through optimized sulfonic acid group density (equivalent weight 400-900 g/equivalent).
Solution Approach 2:
The patent creates a composite polymer structure combining perfluorinated backbone units with side chains containing sulfonic acid groups. This composite architecture allows the perfluorinated segments to provide mechanical strength and dimensional stability while the sulfonic acid-containing segments provide ionic conductivity for power generation.
2Reliability
If the equivalent weight of the polymer is reduced to achieve low electrical resistance, then power generation performance is improved, but the molecular weight becomes insufficient and mechanical strength deteriorates
Solution Approach 1:
The patent changes the molecular weight parameters by optimizing the equivalent weight to 400-900 g/equivalent, which balances ionic conductivity with mechanical strength. The perfluorinated structure provides high molecular weight and strength while the side chain architecture ensures sufficient sulfonic acid group density for low electrical resistance.
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 low electrical resistance, high heat resistance, and improved durability, enabling stable power generation at higher temperatures and extending the lifespan of the membrane/electrode assembly.
Implementation Method 1
a polymer having a low electrical resistance... a polymer electrolyte membrane for polymer electrolyte fuel cells having a low electrical resistance
Implementation Method 2
the polymer will be excessively swollen with water, whereby the mechanical strength of the resulting polymer electrolyte membrane will be insufficient
Implementation Method 3
the polymer electrolyte membrane undergoes repeats of swelling in a wet state and shrinkage in a dry state, whereby the polymer electrolyte membrane is likely to be cracked and damaged
Data Source
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AI summary
To provide a polymer electrolyte membrane for polymer electrolyte fuel cells, which has a low electrical resistance, high heat resistance and is strong against repeats of swelling and shrinkage; and a membrane/electrode assembly having high power generation performance and excellent in durability. For a polymer electrolyte membrane 15, a polymer comprising units (U1) and units (U2) is used: Q1, Q2, Q3: a perfluoroalkylene group or the like; Rf1, Rf2: a perfluoroalkyl group; X1, X2: an oxygen atom or the like; a, b: 0 or the like; Y1, Y2: a fluorine atom or the like; and s, t: 0 to 1.