Alkaline Electrolysis Diaphragm Pore Size Optimization
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Solution Overview
Problem
Existing diaphragms for alkaline water electrolysis face issues with voltage loss due to gas bubble attachment, hydrophilic inorganic particle detachment, and reduced ion permeability, especially in variable power supply environments, where pressure variations and liquid streams cause hydrophilicity loss and particle detachment.
Innovation Solution
A diaphragm with a porous polymer membrane comprising a polymer resin and hydrophilic inorganic particles, where the average pore sizes at the surfaces are between 0.5 μm and 2.0 μm, and the ratio of mode particle size to average pore size is 2.0 or more, maintaining high hydrophilicity and ion permeability by adjusting the porosity and bubble point resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous membrane structure is used to increase ion permeability, then ion permeability is improved, but gas bubbles attach to the surface and close the pores, causing voltage loss increase
Solution Approach 1:
The diaphragm employs a porous polymer membrane structure with controlled pore sizes (0.5-2.0 μm) to achieve high ion permeability while maintaining gas impermeability. The porous structure allows efficient ion transport during electrolysis without compromising the membrane's ability to separate gases.
Solution Approach 2:
The diaphragm is constructed as a composite material combining polymer resin with hydrophilic inorganic particles (such as zirconium oxide, bismuth oxide, or cerium oxide). This composite structure provides both the mechanical integrity of the polymer and the hydrophilic properties needed to prevent gas bubble attachment, while the inorganic particles enhance ion permeability and maintain surface wetting during operation.
2Reliability
If hydrophilic inorganic particles are incorporated to maintain hydrophilicity, then gas bubble attachment is reduced, but particles detach under liquid stream and pressure variation, causing hydrophilicity loss
Solution Approach 1:
The patent optimizes critical parameters including pore size (0.5-2.0 μm), porosity (30-60%), and the ratio of inorganic particle size to pore size (2.0 or more). These parameter adjustments ensure that inorganic particles remain firmly embedded in the polymer matrix under varying operating conditions while maintaining the desired hydrophilic properties and ion permeability.
3Reliability
If the diaphragm is sandwiched between electrodes to reduce solution resistance, then electrical conductivity is improved, but pressure variation and liquid stream cause particle detachment and hydrophilicity loss
Solution Approach 1:
The diaphragm combines polymer resin with hydrophilic inorganic particles to create a composite structure that maintains hydrophilicity under pressure variation and liquid stream conditions. The inorganic particles (zirconium oxide, bismuth oxide, cerium oxide) provide stable hydrophilic surfaces that prevent gas bubble attachment while withstanding the mechanical stresses of operation.
Solution Approach 2:
The patent specifies precise parameter ranges including pore size (0.5-2.0 μm), porosity (30-60%), and particle-to-pore size ratio (≥2.0) to ensure the diaphragm maintains its hydrophilic properties and structural integrity when sandwiched between electrodes under varying operating conditions.
4Reliability
If pore size is reduced to improve gas impermeability, then gas separation is improved, but ion permeability decreases, causing voltage loss increase
Solution Approach 1:
The patent optimizes pore size to a specific range (0.5-2.0 μm) that balances gas impermeability and ion permeability. This parameter optimization, combined with controlled porosity (30-60%) and the presence of hydrophilic inorganic particles, enables the membrane to effectively separate gases while maintaining efficient ion transport during electrolysis.
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 diaphragm maintains low voltage loss and good gas impermeability by preventing hydrophilic inorganic particle detachment and ensuring long-term hydrophilicity, even under variable power supply conditions, enhancing the stability and efficiency of alkaline water electrolysis.
Implementation Method 1
The diaphragm is therefore required to have high ion permeability to allow the electrolysis process to take place efficiently. From this viewpoint, diaphragms having a porous structure have been studied as diaphragms that exhibit high ion permeability.
Implementation Method 2
This problem of voltage loss increase is considerably significant if the surfaces of the porous membrane are hydrophobic, because in this case gas bubbles readily attach to the surfaces.
Implementation Method 3
The diaphragm is required to have gas impermeability to prevent mixing of the oxygen gas and hydrogen gas.
Implementation Method 4
Applying direct-current electricity to this electrolyte solution by means of a cathode and an anode induces water electrolysis process.
Data Source
AI summary
The diaphragm for alkaline water electrolysis according to the present invention comprises a porous polymer membrane, the porous polymer membrane comprising a polymer resin and hydrophilic inorganic particles. A porosity of the porous polymer membrane is 30% or more and 60% or less, average pore sizes at both surfaces of the porous polymer membrane is 0.5 μm or more and 2.0 μm or less, and a ratio of a mode particle size of the hydrophilic inorganic particles to the average pore size of the porous polymer membrane (mode particle size/average pore size) is 2.0 or more.