Sulfonic Acid Polymer Electrolyte Membrane With Low Hydrogen Crossover
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Solution Overview
Problem
Existing acid-type sulfonic acid group-containing polymers for polymer electrolyte fuel cells and water electrolyzers face challenges with high hydrogen gas permeability and oligomer generation during production, which complicates the production process and increases costs.
Innovation Solution
A polymer with perfluoromonomer units, no halogen atoms other than fluorine, and acid-type sulfonic acid groups, featuring a hydrogen gas permeation coefficient of at most 2.5×10−9 cm3·cm/(s·cm2·cmHg) and a mass reduction rate of at most 15% in hot water, reducing oligomer generation and simplifying the production process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chlorotrifluoroethylene units are used to improve hot water resistance, then hot water resistance is improved, but oligomer generation increases during production
Solution Approach 1:
The invention changes the chemical composition parameters by completely eliminating chlorotrifluoroethylene units and replacing them with alternative perfluoromonomer units (such as perfluoro(alkyl vinyl ether) units). This parameter change maintains the desired hot water resistance while eliminating the chain transfer agent effect that causes oligomer generation, thereby resolving the contradiction between reliability and harmful byproduct formation.
2Ease of manufacture
If chlorotrifluoroethylene acts as chain transfer agent, then polymerization occurs, but oligomer is generated which complicates production process
Solution Approach 1:
The invention extracts and removes the problematic chlorotrifluoroethylene component from the polymer composition. By taking out this chain transfer agent that causes oligomer generation, the patent eliminates the need for complex post-polymerization treatment steps (precipitation and washing operations), thereby simplifying the overall production process while maintaining polymerization capability through alternative monomer combinations.
3Reliability
If oligomer is contained in polymer, then polymer may be eluted during operation, but removing oligomer complicates production process
Solution Approach 1:
The invention performs preliminary action by preventing oligomer formation at the source during polymerization, rather than dealing with oligomer removal after polymer formation. By selecting monomers that do not act as chain transfer agents, the patent ensures that oligomers are not generated in the first place, thereby maintaining polymer stability during operation while keeping the production process simple without requiring complex purification steps.
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 exhibits excellent hydrogen gas barrier properties and hot water resistance with reduced oligomer generation, leading to lower fuel consumption, higher durability, and reduced production costs for polymer electrolyte fuel cells and water electrolyzers.
Implementation Method 1
the acid-type sulfonic acid group-containing polymer constituting the polymer electrolyte membrane is required to have low hydrogen gas permeability (hydrogen gas barrier property)
Implementation Method 2
the polymer electrolyte membrane is exposed to high temperature and high humidity conditions, and therefore, the acid-type sulfonic acid group-containing polymer constituting the polymer electrolyte membrane is required to have hot water resistance
Data Source
AI summary
An acid-type sulfonic acid group-containing polymer containing perfluoromonomer units, no monomer units having a halogen atom other than a fluorine atom, and acid type sulfonic acid groups, whose hydrogen gas permeability coefficient under the conditions of a temperature of 80° C. and a relative humidity of 10% is at most 2.5×10−9 cm3·cm/(s·cm2·cmHg), and whose mass reduction rate when immersed in hot water at 120° C. for 24 hours is at most 15 mass %. Liquid composition, membrane electrode assembly, polymer electrolyte fuel cell, and ion exchange membrane utilizing the acid-type sulfonic acid group-containing polymer.