Composite Ionomeric Membrane Dimensional Stability
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Solution Overview
Problem
Composite membranes with fluorinated ionomers and short side chains exhibit high size variations, which reduce their durability and lifespan in fuel cell applications due to ease of breakage during operating cycles.
Innovation Solution
A composite ionomeric membrane with a porous inert support coated with a fluorinated sulphonic ionomer, where the ionomer has specific side chain structures and equivalent weights, and a process involving hydrolysis of precursor groups to form sulphonic acid groups, is developed to achieve reduced size variations and improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fluorinated ionomers with short side chains are used in composite membranes, then good mechanical properties are achieved, but high size variations occur during operating cycles
Solution Approach 1:
The patent applies parameter changes by carefully controlling the equivalent weight of the fluorinated ionomer within a specific range (380-1700 g/eq, preferably 500-1200 g/eq) and the composition ratios of monomers in the copolymer. This optimization of physical and chemical parameters reduces size variations during hydration cycles while preserving the mechanical strength provided by the short side chain structure.
Solution Approach 2:
The patent uses composite materials by combining fluorinated ionomers with a porous inert support (such as PTFE). This composite structure provides both the mechanical properties needed for durability and the dimensional stability required to minimize size variations during operating cycles, effectively resolving the contradiction between strength and precision.
2Reliability
If fluorinated ionomers with short side chains are used, then durability is improved, but size variations increase causing ease of breakage
Solution Approach 1:
The patent resolves this contradiction by optimizing parameters including the equivalent weight range (380-1700 g/eq), monomer composition ratios, and processing conditions. These parameter optimizations ensure that the membrane maintains dimensional stability during hydration cycles, preventing breakage while preserving the durability benefits of short side chain fluorinated ionomers.
Solution Approach 2:
By creating a composite membrane structure with fluorinated ionomer impregnated into a porous inert support, the patent achieves both improved durability from the ionomer and reduced size variations from the stable support structure, thereby preventing breakage during operating cycles.
3Manufacturing precision
If equivalent weight of ionomer is reduced, then size variations are reduced, but mechanical properties may be compromised
Solution Approach 1:
The patent applies parameter changes by defining a specific equivalent weight range (380-1700 g/eq, preferably 500-1200 g/eq) that balances two competing requirements: lower equivalent weights reduce size variations during hydration, while sufficient equivalent weight maintains mechanical properties. This optimized parameter range resolves the contradiction between precision and strength.
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 membrane exhibits size variations of less than 25% in both orthogonal directions, enhancing its mechanical stability and durability for fuel cell applications.
Implementation Method 1
a process involving hydrolysis of precursor groups to form sulphonic acid groups
Data Source
AI summary
A composite ionomeric membrane comprising a layer or film of a porous inert material on which a (per) fluorinated sulphonic ionomer is deposited wherein the sulphonic groups are at the end of short side chains (SSC), said ionomer having:equivalent weight comprised between 280 and 1,700 g/eq;side chains of formula: —O—CF2—CF2—S03−M+, wherein M is hydrogen or an alkaline metal;said membrane having in each of the two orthogonal directions xy of the plane, after dipping in demineralized water at 100° C. for 30 minutes and preliminary drying at 105° C. under vacuum for one hour, the following size variations:in one direction, size variation lower than 25%;in the other direction, size variation lower than 20%.