Sandwich-Structured Anion Exchange Membrane for Low-Crossover Flow Batteries
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Solution Overview
Problem
Existing redox flow batteries face challenges with high costs due to expensive membranes that have low ion selectivity and high electrolyte crossover, leading to reduced voltage, coulombic, and energy efficiencies.
Innovation Solution
A sandwich-structured thin film composite anion exchange membrane is developed, comprising a microporous substrate, a hydrophilic ionomeric polymer coating, and a cross-linked protonated polyamine anion exchange polymer layer, which selectively conducts protons and anions while rejecting cations, enhancing ionic conductivity and reducing electrolyte crossover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional membranes are used in redox flow batteries, then the system structure is simple, but ion selectivity is low and electrolyte crossover is high, leading to reduced voltage, coulombic, and energy efficiencies
Solution Approach 1:
The patent applies composite materials by creating a sandwich-structured membrane consisting of a microporous substrate layer combined with functional polymer coating layers. The substrate provides mechanical strength while the coating layers provide ion selectivity and low crossover, resolving the contradiction between simple structure and high performance by integrating multiple material functions into a composite structure.
Solution Approach 2:
The membrane is segmented into distinct functional layers: a microporous substrate layer for mechanical support and ion transport, and separate coating layers for selective ion conduction. This segmentation allows each layer to be optimized for its specific function, improving overall membrane performance without requiring a single complex material.
2Reliability
If conventional membranes are used in redox flow batteries, then manufacturing is simple, but electrolyte crossover is high, leading to reduced coulombic and energy efficiencies
Solution Approach 1:
The functional polymer coating layers are applied preliminarily to the microporous substrate during the manufacturing process. This preliminary action of coating the substrate with selective layers ensures low electrolyte crossover from the outset, achieving high coulombic efficiency while maintaining a relatively simple manufacturing workflow through sequential layer deposition.
3Reliability
If conventional membranes are used in redox flow batteries, then the system is simple to operate, but energy density is low due to high electrolyte crossover
Solution Approach 1:
The sandwich-structured composite membrane combines a microporous substrate with functional polymer coatings, where each layer contributes specific properties. The substrate provides mechanical integrity and basic ion transport, while the coating layers provide selective ion conduction and low crossover, achieving high energy efficiency through material composition rather than operational complexity.
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 new membrane improves voltage, coulombic, and energy efficiencies, and increases energy density by minimizing electrolyte crossover, thus optimizing the performance of redox flow batteries.
Implementation Method 1
a cross-linked protonated polyamine anion exchange polymer coating layer on top of the first hydrophilic ionomeric polymer coating layer
Implementation Method 2
selectively conducts protons and anions while rejecting cations
Implementation Method 3
a first hydrophilic ionomeric polymer coating layer on the surface of the microporous substrate layer
Data Source
AI summary
A low cost, sandwich-structured thin film composite (TFC) anion exchange membrane for redox flow batteries, fuel cells, electrolysis, and other electrochemical reaction applications is described. The sandwich-structured TFC anion exchange membrane comprises a microporous substrate membrane, a first hydrophilic ionomeric polymer coating layer on the surface of the microporous substrate layer, a cross-linked protonated polyamine anion exchange polymer coating layer on top of the first hydrophilic ionomeric polymer coating layer, and a second hydrophilic ionomeric polymer protective layer on top of the cross-linked protonated polyamine anion exchange polymer coating layer. Methods of making the TFC anion exchange membrane comprises a microporous substrate membrane and redox flow battery system incorporating the TFC anion exchange membrane comprises a microporous substrate membrane are also described.