Polymer Electrolyte Membrane Mechanical Strength
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Solution Overview
Problem
Polymer electrolyte fuel cells face issues with membrane breakage due to repeated humidification and drying cycles, leading to wrinkles and potential breakage, and catalyst layer cracking, which affects power generation performance.
Innovation Solution
A polymer with specific units and a molar ratio, derived from perfluoroalkylene groups and tetrafluoroethylene, is used to create a membrane with enhanced mechanical strength and chemical durability, reducing the likelihood of breakage and cracking in the membrane and catalyst layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the polymer electrolyte membrane is thinned to reduce resistance and improve power generation performance, then electrical resistance decreases and power generation performance improves, but mechanical strength decreases and breakage becomes more likely
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer by controlling the molar ratio of specific fluorinated monomer units (where the molar ratio of unit (u2) to total units (u1)+(u2) is 0.05 to 0.3). This compositional parameter change allows the membrane to maintain adequate mechanical strength even at reduced thickness, enabling thinning to reduce electrical resistance without proportionally sacrificing mechanical strength
Solution Approach 2:
The patent creates a composite polymer structure incorporating multiple fluorinated monomer units with different properties (ion-exchange groups, perfluoroalkyl groups, etheric oxygen atoms). This composite material approach allows simultaneous optimization of electrical conductivity (for low resistance) and mechanical strength (for breakage resistance) within the same membrane structure
2Productivity
If the polymer electrolyte membrane is thinned, then power generation performance improves, but reliability under humidification and drying cycles deteriorates
Solution Approach 1:
The patent modifies the polymer's chemical composition by incorporating specific fluorinated units (u1 and u2) with ion-exchange groups and perfluoroalkyl chains in controlled ratios. This parameter change enhances the membrane's dimensional stability and mechanical integrity during humidification-drying cycles, allowing thin membranes to maintain reliability while improving power generation performance
Solution Approach 2:
The patent introduces localized structural features through specific monomer units containing ion-exchange groups and perfluoroalkyl side chains. These local structural modifications create regions of enhanced mechanical strength and swelling control within the membrane matrix, improving reliability under cyclic humidification and drying conditions
3Productivity
If the catalyst layer contains a large amount of catalyst, then power generation performance improves, but cracking becomes more likely
Solution Approach 1:
The patent adjusts the chemical composition parameters of the polymer matrix (controlling the ratio of fluorinated units with ion-exchange groups to perfluoroalkyl units) to create a more flexible and crack-resistant matrix structure. This allows the catalyst layer to accommodate high catalyst content while maintaining structural integrity and preventing cracking
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 and catalyst layer exhibit improved resistance to humidification and drying cycles, maintaining mechanical strength and power generation performance even at thin thicknesses, with reduced risk of breakage and cracking.
Implementation Method 1
The polymer electrolyte membrane contains an ion-exchange resin, and thus will be swelled by humidification and will shrink by drying
Data Source
Figure 1~2
AI summary
To provide a polymer capable of forming a polymer electrolyte membrane that is resistant to breakage even when being repeatedly subjected to humidification and drying or a catalyst layer that is resistant to formation of cracks; a polymer electrolyte membrane employing said polymer; and a membrane/electrode assembly for a polymer electrolyte fuel cell. A polymer comprising units (u1) having two ion-exchange groups and units (u2) of e.g. a perfluoro(alkyl vinyl ether), wherein the molar ratio (u2)/((u1)+(u2)) is more than 0.30 and at most 0.70. A membrane/electrode assembly 10 comprising an anode 13 having a catalyst layer 11 and a gas diffusion layer 12, a cathode 14 having a catalyst layer 11 and a gas diffusion layer 12, and a polymer electrolyte membrane 15 disposed between the anode 13 and the cathode 14 in a state of being contact with the catalyst layers 11, wherein either one or each of the catalyst layers 11 and the polymer electrolyte membrane 15 contains the aforementioned polymer.