Ion Exchange Membrane Layer Segmentation for Alkali Chloride Electrolysis
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Solution Overview
Problem
Conventional ion exchange membranes for alkali chloride electrolysis face challenges in achieving both low membrane resistance and high peeling resistance, leading to increased electrolysis voltage and potential peeling issues due to differences in ion exchange capacity between layers.
Innovation Solution
The ion exchange membrane is designed with a layer of fluorinated polymer having carboxylic acid functional groups and multiple layers of fluorinated polymer with sulfonic acid functional groups, where the reinforcing material is positioned in a specific configuration to minimize contact with the layer of lower ion exchange capacity, optimizing the ion exchange capacity and thickness ratios to reduce membrane resistance and prevent peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ion exchange capacity of the polymer B layer is made high to lower membrane resistance, then the membrane resistance decreases, but peeling occurs due to water content difference between layers
Solution Approach 1:
The polymer B layer is divided into two sub-layers: a first polymer B layer adjacent to the polymer A layer with lower ion exchange capacity, and a second polymer B layer with higher ion exchange capacity. This segmentation allows the first layer to maintain water content compatibility with adjacent layers (preventing peeling) while the second layer provides high ion exchange capacity (lowering membrane resistance).
Solution Approach 2:
Different regions of the polymer B layer are assigned different ion exchange capacities tailored to their specific functional requirements. The region adjacent to the polymer A layer has lower ion exchange capacity to match water content and prevent peeling, while the region farther from the polymer A layer has higher ion exchange capacity to reduce membrane resistance. This local optimization resolves the contradiction between peeling resistance and membrane resistance.
2Strength
If the ion exchange capacity of the polymer B layer is made small to suppress peeling, then peeling resistance improves, but membrane resistance becomes high increasing electrolysis voltage
Solution Approach 1:
The polymer B layer is segmented into two functional zones: the first polymer B layer (adjacent to polymer A) with lower ion exchange capacity ensures peeling resistance by matching water content, while the second polymer B layer with higher ion exchange capacity ensures low membrane resistance. This segmentation allows both requirements to be satisfied simultaneously in different regions.
Solution Approach 2:
The invention applies local quality by assigning different ion exchange capacities to different portions of the polymer B layer based on their functional needs. The first layer portion prioritizes peeling resistance with lower ion exchange capacity, while the second layer portion prioritizes membrane resistance with higher ion exchange capacity, thereby resolving the contradiction.
3Reliability
If the polymer B layer is made thin to reduce membrane resistance, then membrane resistance decreases, but the reinforcing material shields alkali metal ion transfer increasing membrane resistance
Solution Approach 1:
The polymer B layer is segmented into two layers with different ion exchange capacities. The first polymer B layer (thinner, lower ion exchange capacity) is positioned between the polymer A layer and the reinforcing material, allowing it to minimize shielding while the second polymer B layer (thicker, higher ion exchange capacity) provides the necessary ion exchange function. This segmentation optimizes the balance between reducing membrane resistance and minimizing shielding effects.
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 configuration results in a membrane with high strength, low resistance, and reduced electrolysis voltage, while preventing peeling between layers, effectively addressing the trade-off between electrolysis voltage and peeling resistance.
Implementation Method 1
an electrolyte membrane made of a fluorinated polymer having ion exchange groups (carboxylic acid functional groups, sulfonic acid functional groups, etc.)
Implementation Method 2
the difference in water content increases due to the difference in the ion exchange capacity between the polymer B layer, and the peeling (so-called water blisters) due to the difference in electrodialysis water between the polymer B layer and C layer may occur
Data Source
AI summary
To provide an ion exchange membrane for alkali chloride electrolysis for which membrane strength is increased while membrane resistance is reduced to reduce electrolysis voltage during alkali chloride electrolysis and which prevents peeling between layers (S) and a layer (C). The ion exchange membrane for alkali chloride electrolysis comprises a layer (C) which comprises a fluorinated polymer having carboxylic acid functional groups, at least two layers (S) which comprise a fluorinated polymer having sulfonic acid functional groups, and a reinforcing material, wherein the layers (S) include a layer (Sa) and a layer (Sb), the layer (Sa) is a layer which is adjacent to the layer (C), the layer (Sb) is a layer which is not adjacent to the layer (C), the reinforcing material is disposed in the layer (Sb) substantially in parallel to the layer (Sb) in a state not in contact with the layer (Sa), and the ion exchange capacity of the layer (Sa) is lower than the ion exchange capacity of the layer (Sb).