Thin Porous Separator for Alkaline Water Electrolysis
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Solution Overview
Problem
Current separators for alkaline water electrolysis face a trade-off between mechanical strength and ionic conductivity, with thicker porous supports decreasing efficiency while thinner supports may compromise physical strength.
Innovation Solution
A separator design featuring a porous support with a thickness of 150 μm or less, combined with first and second porous layers on either side, optimized for ionic resistance and pore diameter to enhance mechanical qualities and ion conductivity, using a dope solution comprising polymer resin, hydrophilic particles, and solvent, and a phase inversion process to form a three-dimensional porous polymer network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a porous support with greater thickness is used to enhance mechanical strength, then the physical strength and structural stability are improved, but the ionic conductivity through the separator decreases
Solution Approach 1:
The patent applies this principle by using a thin porous support (150 μm or less) instead of a thick rigid support, achieving both mechanical adequacy and high ionic conductivity. The thin film structure reduces ionic resistance while maintaining sufficient structural strength through optimized porosity and material properties.
Solution Approach 2:
The patent utilizes porous materials with optimized pore structure and porosity to enhance ionic conductivity. The porous support and porous layers are designed with specific porosity ranges (30-70% and 40-60% respectively) to facilitate hydroxyl ion transport while maintaining mechanical integrity through the three-dimensional porous polymer network.
2Reliability
If a porous support with thickness of 150 μm or less is used to improve ionic conductivity, then the efficiency of electrolytic process is improved, but the mechanical strength may be compromised
Solution Approach 1:
The patent applies composite materials by combining the porous support with porous layers formed from dope solution containing polymer resin and hydrophilic particles. This composite structure enhances mechanical strength while maintaining high ionic conductivity, as the porous layers provide additional structural support and ion transport pathways.
Solution Approach 2:
The three-dimensional porous polymer network formed in the porous layers provides both mechanical reinforcement and ion conduction pathways. The optimized porosity (40-60%) and pore diameter (0.1-1.0 μm) of these layers compensate for the reduced thickness of the porous support, ensuring sufficient mechanical strength is achieved.
3Reliability
If the separator thickness is reduced to 250 μm or less to enhance ion conductivity, then the ionic resistance is reduced, but the structural stability and handling properties deteriorate
Solution Approach 1:
The patent uses composite materials consisting of the porous support combined with porous layers having optimized porosity and pore structure. This composite construction provides the necessary structural stability and handling properties for a thin separator (250 μm or less) while maintaining high ionic conductivity through the optimized porous architecture.
Solution Approach 2:
The patent applies local quality by optimizing different regions of the separator with specific properties. The porous support has one porosity range (30-70%) while the porous layers have a different porosity range (40-60%), with each region tailored to provide specific functions - the support provides structural framework while the porous layers enhance ion transport and mechanical reinforcement.
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 solution achieves a balance between mechanical strength and high ionic conductivity, with an ionic resistance of less than 0.1 ohm·cm² at 80°C in a 30 wt % aqueous KOH solution, ensuring efficient hydrogen and oxygen separation and transportation of hydroxyl ions.
Implementation Method 1
the separator should also be a highly ionic conductor for transportation of hydroxyl ions from the cathode to the anode
Implementation Method 2
a phase inversion process to form a three-dimensional porous polymer network
Data Source
AI summary
A separator for alkaline electrolysis comprising a porous support (10) and a first (20b) and second (30b) porous layer provided on respectively one side and the other side of the porous support, characterized in that the porous support has a thickness (d1) of 150 μm or less and the total thickness (d2) of the separator is less than 250 μm. Also a method is disclosed wherewith such a separator may be prepared.