Ion Exchange Membrane Layer Architecture for Electrolysis

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Solution Overview

Problem

Conventional ion exchange membranes face challenges in simultaneously achieving high membrane strength and excellent electrolytic performance, particularly in alkali chloride electrolysis, where they are required to operate at high current efficiency with low electrolytic voltage and low impurity concentration.

Innovation Solution

The ion exchange membrane is configured with a specific layer configuration, where the ion cluster diameter ratio of the sulfonic acid layer to the carboxylic acid layer is controlled between 0.67 and 0.89, and the ion exchange capacity of the carboxylic acid layer is set to 0.81 mEq/g or more, enhancing both membrane strength and electrolytic performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the ion exchange membrane uses a conventional structure, then the membrane strength is maintained, but the electrolytic performance deteriorates with higher voltage and lower current efficiency

Engineering Contradiction:
Improveelectrolytic performanceVSAvoidmembrane strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The ion exchange membrane is divided into multiple layers with distinct functions: a first ion exchange membrane layer containing sulfonic acid groups for high ion conductivity and low electrolytic voltage, and a second ion exchange membrane layer containing carboxylic acid groups for enhanced membrane strength and peeling resistance. This segmentation allows each layer to optimize its specific function while working together as an integrated system.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the membrane structure are assigned different chemical properties and functionalities. The first layer has high sulfonic acid group content for optimal ion transport, while the second layer has carboxylic acid groups for mechanical reinforcement. The ion cluster diameter ratio between layers is specifically controlled (0.67-0.89) to achieve local optimization of both electrolytic performance and structural integrity.

Inventive Principle:
Principle #3Local quality

2Productivity

If the ion exchange membrane structure is modified to improve electrolytic performance, then current efficiency increases, but membrane strength and peeling resistance deteriorate

Engineering Contradiction:
Improvecurrent efficiencyVSAvoidpeeling resistance
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The membrane combines two different ion exchange polymer materials with complementary properties: a sulfonic acid-containing polymer providing high ion conductivity and current efficiency, and a carboxylic acid-containing polymer providing mechanical strength and peeling resistance. The composite structure achieves synergistic effects where the combination of materials performs better than individual materials alone.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention optimizes specific parameters including the ion cluster diameter ratio between layers (0.67-0.89), the ion exchange capacity of the carboxylic acid layer (0.81 mEq/g or more), and the thickness ratio of the layers. These parameter optimizations ensure high current efficiency while maintaining adequate peeling resistance through precise control of structural characteristics.

Inventive Principle:
Principle #35Parameter changes

3Strength

If the ion exchange capacity of the carboxylic acid layer is increased, then membrane strength improves, but the ion cluster diameter ratio may deviate from optimal range affecting electrolytic performance

Engineering Contradiction:
Improvemembrane strengthVSAvoidelectrolytic performance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention establishes specific parameter ranges to balance competing requirements: ion exchange capacity of the carboxylic acid layer ≥0.81 mEq/g for sufficient strength, and ion cluster diameter ratio between 0.67-0.89 for optimal electrolytic performance. These parameter specifications ensure both mechanical integrity and electrochemical efficiency are simultaneously achieved.

Inventive Principle:
Principle #35Parameter changes

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 an ion exchange membrane with improved membrane strength and electrolytic performance, including reduced peeling resistance and maintained current efficiency, while preventing voltage increases and electrode damage.

Implementation Method 1

an ion exchange membrane having a layer A containing a fluorine-containing polymer having a sulfonic acid group (4) and a layer B containing a fluorine-containing polymer having a carboxylic acid group (5)

Methodology Applied
Scientific EffectIon exchange: Ion Exchange

Data Source

PatentEP3299407B1Ion exchange membrane
Publication Date: 2022.03.16 ASAHI KASEI KOGYO KABUSHIKI KAISHA
  • EP3299407B1 patent drawingFigure 1
  • EP3299407B1 patent drawingFigure 2
  • EP3299407B1 patent drawing

AI summary

The ion exchange membrane according to the present invention comprises a layer A comprising a fluorine-containing polymer having a sulfonic acid group and a layer B comprising a fluorine-containing polymer having a carboxylic acid group, wherein an ion exchange capacity of the layer B is 0.81 mEq/g or more, and a value of (an ion cluster diameter of the layer B) / (an ion cluster diameter of the layer A) is 0.67 to 0.89.