Ion-Exchange Polymer Composition for Crack-Resistant Fuel Cell Layers
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Solution Overview
Problem
Catalyst layers and polymer electrolyte membranes in polymer electrolyte fuel cells, particularly those with perfluoromonomers having ion exchange groups, are prone to breaking during formation due to fragility.
Innovation Solution
A liquid composition comprising a polymer with ion exchange groups, water, and an organic solvent, where the average secondary particle size of the polymer is between 100 to 3,000 nm and the primary particle size parameter (average primary particle size corrected by ion exchange capacity) is between 12 to 20, is used to form catalyst layers and membranes that are less likely to break during formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer having ion exchange groups (particularly perfluoromonomers with 5-membered rings) is used to form catalyst layer and polymer electrolyte membrane, then ion exchange capacity and electrochemical performance are improved, but the catalyst layer and membrane become fragile and readily broken during formation
Solution Approach 1:
The patent changes the particle size parameter of the polymer from its conventional range to a specific range (average primary particle size of 0.01 to 1 μm, with average secondary particle size of 0.1 to 10 μm). This parameter change resolves the contradiction by maintaining ion exchange capacity while improving mechanical strength and reducing brittleness during formation.
Solution Approach 2:
The patent applies local quality by creating a specific particle size distribution where primary particles and secondary particles have different size characteristics. This local differentiation in particle structure allows the polymer to maintain both high ion exchange capacity and improved mechanical properties, resolving the fragility issue while preserving electrochemical performance.
2Ease of manufacture
If conventional liquid composition is used to form catalyst layer and polymer electrolyte membrane, then formation process is simple, but the catalyst layer and membrane are readily broken during formation
Solution Approach 1:
The patent modifies the liquid composition by controlling the particle size parameters of the polymer (average primary particle size: 0.01 to 1 μm, average secondary particle size: 0.1 to 10 μm). This parameter change enables the use of simple conventional formation processes while preventing catalyst layer and membrane breakage, thus resolving the contradiction between manufacturing simplicity and structural integrity.
3Stability of the object's composition
If polymer with smaller primary particle size is used, then dispersibility in liquid composition is improved, but mechanical strength and resistance to breaking during formation deteriorates
Solution Approach 1:
The patent optimizes the particle size parameters by defining specific ranges for both primary particles (0.01 to 1 μm) and secondary particles (0.1 to 10 μm). This dual-parameter optimization resolves the contradiction by ensuring adequate dispersibility through controlled primary particle size while maintaining mechanical strength through appropriate secondary particle size formation.
Solution Approach 2:
The patent transitions from considering only primary particle size to a two-dimensional particle size characterization system (primary and secondary particles). This dimensional expansion in parameter space allows simultaneous optimization of dispersibility and mechanical strength, resolving the contradiction between these opposing requirements.
Data Source
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AI summary
To provide a liquid composition with which a catalyst layer and a polymer electrolyte membrane will hardly be broken at the time of their formation and a method for producing the liquid composition; and a method for producing a membrane/electrode assembly by which a catalyst layer and a polymer electrolyte membrane will hardly be broken at the time of their formation. A liquid composition comprising a polymer having ion exchange groups, water and an organic solvent, wherein the average secondary particle size of the polymer having ion exchange groups is from 100 to 3,000 nm, and the primary particle size parameter represented by the product of the average primary particle size (nm) and the ion exchange capacity (meq/g dry resin) of the polymer having ion exchange groups, is from 12 to 20.