Aromatic Perfluoroalkane Monomer for Fuel Cell Membranes
Solution Overview
Problem
Current polymers used in fuel cells, such as Nafion®, face challenges including reduced performance at high temperatures, increased permeability to methanol, limited chemical stability, swelling issues, and high production costs, as well as environmental and safety concerns, which are not adequately addressed by existing aromatic polymers.
Innovation Solution
A new aromatic perfluoroalkane monomer is developed, allowing for the synthesis of polymers with improved chemical stability, dimensional stability, and ionic conductivity, which can be easily reinforced with ePTFE without aggressive surface treatments, and maintains performance comparable to commercial membranes like Nafion®.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Nafion® type polymers are used for fuel cell membranes, then ionic conductivity is improved, but chemical stability deteriorates due to swelling and dimensional changes
Solution Approach 1:
The patent employs a composite structure combining aromatic polyimide backbone with perfluorosulfonic acid side chains. This composite material approach allows the rigid aromatic backbone to provide dimensional stability while the perfluorosulfonic acid groups maintain ionic conductivity, resolving the contradiction between conductivity and stability
Solution Approach 2:
The patent applies local quality by differentiating the functional roles of different parts of the polymer structure: the aromatic polyimide backbone provides mechanical strength and dimensional stability, while the perfluorosulfonic acid side chains localized on the backbone provide ionic conductivity. This spatial differentiation of properties resolves the contradiction
2Temperature
If Nafion® type polymers are used for high temperature operation, then performance is improved, but permeability to methanol increases
Solution Approach 1:
The patent changes the chemical parameters of the polymer by introducing aromatic polyimide structures with rigid backbones and controlled free volume. This parameter change allows the membrane to maintain low methanol permeability at elevated temperatures while preserving ionic conductivity, addressing the contradiction between temperature performance and methanol rejection
3Ease of manufacture
If aromatic polymers are used to replace aliphatic polymers, then cost is reduced, but mixing compatibility with ePTFE deteriorates
Solution Approach 1:
The patent applies local quality by introducing fluorinated segments specifically at the interface regions where mixing with ePTFE occurs. These fluorinated local regions provide compatibility with ePTFE, while the bulk aromatic polyimide structure maintains cost advantages, resolving the contradiction between cost and compatibility
4Stability of the object's composition
If membrane reinforcement is implemented to limit dimensional changes, then chemical stability is improved, but device complexity increases
Solution Approach 1:
The patent extracts the reinforcement function from a separate structural component and integrates it directly into the polymer backbone itself. The rigid aromatic polyimide backbone inherently provides dimensional stability without requiring additional reinforcement layers or complex composite structures, thus improving stability while maintaining simplicity
Data Source
Figure 1A~1C
Figure 2A~2C
Figure 3A~3C
AI summary
Sulphur-containing and sulphone-containing aromatic perfluoroalkane monomer that can be used for the manufacture of a polymer membrane intended for a fuel cell of PEM type, said functionalized monomer corresponding to the formula (I): E1 - Ar1 - X1 - (CF2)n - X2 - Ar2 - E2 in which: - n is within a range from 1 to 20; - the symbols X1 and X2, which may be identical or different, represent S, SO or SO2; - the symbols Ar1 and Ar2, which may be identical or different, represent a phenylene group, at least one of which bears a -SO3H sulphonic group or an -SO3M sulphonate group, M representing an alkali metal cation; - the symbols E1 and E2, which may be identical or different, represent an electrophilic function, preferably a halogen such as fluorine or chlorine.