Membrane Electrode Assembly Protective Ionomer Layer
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Solution Overview
Problem
Existing methods for manufacturing proton exchange membrane (PEM) fuel cell membrane electrode assemblies face challenges in efficiently and cost-effectively forming separate layers into a composite sheet without defects, such as air-displacement and cohesive failures, and issues with ionomer penetration into porous substrates that disrupt electrode performance.
Innovation Solution
A method involving an air-permeable backer, preferably expanded polytetrafluoroethylene (ePTFE), is used to deposit an electrode and a mixture containing perfluorosulfonic acid ionomer, with a protective ionomer layer formed by drying an aqueous wet layer comprising high water content and low water-insoluble alcohol, preventing disruption and enhancing mechanical properties for continuous web handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a porous reinforcement layer is applied to a wet ionomer layer to form a membrane electrode assembly, then the structural integrity and mechanical strength are improved, but the ionomer penetrates into the porous support which disrupts electrode performance
Solution Approach 1:
A protective ionomer layer is deposited on the electrode surface before applying the porous reinforcement layer. This preliminary protective layer prevents ionomer penetration into the porous support during subsequent processing steps, thereby maintaining electrode performance while still allowing the reinforcement layer to provide mechanical strength.
Solution Approach 2:
The protective ionomer layer acts as an intermediary barrier between the electrode and the porous reinforcement layer. It prevents direct interaction and unwanted penetration of ionomer into the porous support, while still allowing the reinforcement layer to bond to the electrode through the protective layer during hot pressing.
2Strength
If separate layers are bonded together with heat and pressure to form a composite sheet, then the mechanical strength and structural integrity are improved, but air-displacement defects and cohesive failures occur
Solution Approach 1:
The protective ionomer layer is deposited beforehand to create a uniform, defect-free surface that facilitates proper bonding during hot pressing. This preliminary layer prevents air entrapment and ensures uniform contact between layers, eliminating air-displacement defects and cohesive failures while maintaining mechanical 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
This method ensures a robust, defect-free membrane electrode assembly with improved mechanical properties and electrochemical performance by forming a protective ionomer layer that prevents ionomer penetration and maintains electrode integrity, allowing for efficient gas access and stable fuel cell operation.
Implementation Method 1
drying an aqueous wet layer comprising high water content and low water-insoluble alcohol
Implementation Method 2
air-permeable backer, preferably expanded polytetrafluoroethylene (ePTFE)
Data Source
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AI summary
Disclosed herein is a method of making a component of a membrane electrode assembly. The method includes forming an electrode on an air-permeable backer comprising ePTFE, depositing a mixture comprising ionomer and a water-insoluble alcohol onto said electrode, drying said mixture to form a protective ionomer layer, and depositing an ePTFE-reinforced ionomer layer onto said protective ionomer layer.