Crosslinked Anion Exchange Membrane for Low Hydrogen Crossover
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Solution Overview
Problem
Current anion exchange membranes (AEMs) for electrochemical devices lack membranes that satisfy the required properties of mechanical stability, low hydrogen crossover, low water uptake, and good conductivity, particularly due to the infancy of AEM technology and limited available membranes that can operate in mildly alkaline environments without the need for corrosive acidic conditions.
Innovation Solution
A method of manufacturing an anion exchange membrane involving the purification of a thermoplastic elastomer with an aromatic ring, halomethylation, casting, amination with specific amines, and crosslinking during the amination step, using a combination of monoamines, diamines, and polyamines to achieve the desired properties, such as styrene content between 30wt% and 70wt% and functionalization degree between 1% and 50%, which enhances mechanical strength and conductivity while reducing hydrogen crossover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional AEM manufacturing methods are used, then membrane production is possible, but the membranes lack mechanical stability and have high hydrogen crossover
Solution Approach 1:
The patent employs a composite structure consisting of a polyolefin substrate providing mechanical strength and an ion-exchange coating layer providing ion transport functionality. This composite approach allows the membrane to achieve both mechanical stability from the substrate and low hydrogen crossover from the functional coating layer, resolving the contradiction between strength and hydrogen crossover prevention.
Solution Approach 2:
The invention applies different materials and properties to different layers of the membrane: the substrate layer is designed for mechanical support with high strength and low permeability, while the coating layer is optimized for ion exchange functionality with appropriate porosity and conductivity. This local differentiation allows each layer to excel at its specific function, achieving both mechanical stability and low hydrogen crossover.
2Reliability
If AEM technology is adopted, then sustainability and reduced corrosiveness are achieved, but limited membrane options with insufficient properties are available
Solution Approach 1:
The membrane is divided into two functional segments: a substrate layer for mechanical support and a coating layer for ion exchange. This segmentation allows independent optimization of each layer's properties, enabling the development of AEMs with tailored characteristics that satisfy diverse application requirements while maintaining sustainability.
Solution Approach 2:
The patent enables control of key membrane parameters including ion exchange capacity, porosity, thickness, and mechanical strength through adjustment of coating composition, deposition conditions, and substrate selection. This parameter control provides versatility in meeting different application specifications while maintaining the sustainability benefits of AEM technology.
3Quantity of substance
If ion exchange membrane functionality is implemented, then ion transfer is enabled, but mechanical strength and stability are compromised
Solution Approach 1:
The composite structure separates the mechanical support function (substrate) from the ion transfer function (coating layer). The substrate provides robust mechanical strength while the porous coating layer enables ion transport, allowing both requirements to be satisfied simultaneously without compromising either property.
Solution Approach 2:
Different regions of the membrane are optimized for different functions: the dense substrate layer for mechanical strength and the porous coating layer for ion transfer. This local quality differentiation enables the membrane to achieve both high mechanical strength and effective ion transfer capability.
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 resulting AEM exhibits improved mechanical strength, reduced hydrogen crossover, and optimized conductivity, making it suitable for use in electrolysers, fuel cells, and other electrochemical devices without the need for platinum group metals, thus offering a more sustainable and less corrosive alternative to traditional PEM systems.
Implementation Method 1
halomethylating the purified TPE
Implementation Method 2
aminating the purified and halomethylated TPE with at least a first amine and a second amine
Implementation Method 3
crosslinking of the membrane occurs during the amination step
Implementation Method 4
Ion exchange membranes, either AEM or PEM, are semi-permeable allowing only certain ions to cross from one side to another
Data Source
Figure 1~1G
Figure 2a~2b
Figure 2c~3
AI summary
This invention relates to an an-ion exchange membrane and method for making said membrane. The membrane being intended for use in electrolysers or other AEM electrochemical devices. The membrane comprises: a thermoplastic elastomer (TPE) comprising styrene, said TPE being a polymeric backbone, wherein: the styrene content of the thermoplastic elastomer is between 30wt% and 70wt%, and crosslinking of a first polymeric backbone to one or more other polymeric backbones, and one or more cationic groups, and the functionalisation degree is between 1% and 50%.