Zero-Gap Brine Electrolyzer Anode with Controlled Surface Roughness
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Solution Overview
Problem
Existing zero-gap brine electrolyzers face challenges in reducing electrolytic voltage due to insufficient liquid permeability and surface area of the catalyst layer, particularly when operated at low current densities, and previous methods for surface roughening do not effectively control the maximum height difference of surface irregularities.
Innovation Solution
A zero-gap brine electrolyzer with an anode featuring a liquid-permeable conductive substrate and a catalyst layer with a maximum height difference of 55 to 70 μm, formed through sand blasting and acid treatment, ensuring sufficient liquid permeability and increased surface area to reduce electrolytic voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the cathode is brought into tight contact with the ion-exchange membrane to reduce electrolytic voltage, then the electrolytic voltage is reduced, but the pressing pressure on the anode increases
Solution Approach 1:
The anode employs a porous conductive substrate with controlled pore structure that allows liquid permeation while maintaining mechanical stability under pressing pressure. The porous structure distributes the pressure across multiple support points, preventing membrane damage while maintaining tight contact for low electrolytic voltage.
Solution Approach 2:
The anode uses a composite structure combining a conductive substrate with a catalyst layer having controlled surface irregularities (5-50 μm height difference). This composite design provides both electrical conductivity and mechanical cushioning, allowing the anode to withstand pressing pressure while maintaining effective contact with the ion-exchange membrane.
2Loss of energy
If the catalyst layer surface is highly roughened to increase surface area, then the electrolytic voltage is reduced, but the liquid permeability decreases
Solution Approach 1:
The conductive substrate is designed with a porous structure that provides liquid permeation pathways through the anode assembly. The porous nature allows electrolyte to flow through the catalyst layer while the controlled surface irregularities (5-50 μm) provide sufficient surface area for catalysis, resolving the contradiction between permeability and surface area.
Solution Approach 2:
The catalyst layer exhibits local quality variations with surface irregularities of controlled height (5-50 μm). These localized surface features increase the effective catalytic surface area without creating a uniformly dense structure that would block liquid permeability. The irregularities are distributed to maintain both functions.
3Strength
If conventional surface roughening methods are used to improve catalyst adhesion, then the catalyst layer adhesion is improved, but the maximum height difference of surface irregularities is not effectively controlled
Solution Approach 1:
The invention specifies precise parameter ranges for surface irregularities, with the maximum height difference controlled to 5-50 μm. This parameter control is achieved through controlled roughening of the conductive substrate before catalyst application, ensuring both adequate adhesion and the surface area needed for low electrolytic voltage without excessive height that would damage the membrane.
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 ensures sufficient liquid permeability and reduces electrolytic voltage without damaging the ion-exchange membrane, even under increased pressure, by optimizing the surface roughness of the catalyst layer, thereby improving the efficiency of the electrolysis process.
Implementation Method 1
An aqueous solution of an alkali metal salt, specifically, an aqueous solution of sodium chloride is electrolyzed to produce chlorine, hydrogen, and sodium hydroxide
Implementation Method 2
subjecting a conductive substrate to sand blasting or acid etching for surface roughening
Implementation Method 3
subjecting a conductive substrate to sand blasting or acid etching for surface roughening
Implementation Method 4
an anode chamber and a cathode chamber separated by a cation-exchange membrane
Implementation Method 5
the liquid pressure is higher on the cathode side than on the anode side so that the electrolyte pressure differs between the anode-side and cathode-side of the ion-exchange membrane
Data Source
AI summary
It is an object of the present invention to provide an anode for a zero-gap brine electrolyzer which through employment of a highly roughened surface at a catalyst layer at an anode for a zero-gap brine electrolyzer makes it possible to achieve sufficient liquid permeability and further reduction in electrolyzing voltage and a brine electrolysis method employing same. The present invention relates to an anode for a zero-gap brine electrolyzer equipped with a liquid-permeable conductive substrate 21, and with a catalyst layer 22 which is provided on the conductive substrate 21 and which is such that the maximum difference in height of surface irregularities is 55 μm to 70 μm; a zero-gap brine electrolyzer equipped with the anode 20, a cathode 30, and an ion-exchange membrane I disposed between and in contact with the anode 20 and the cathode 30; and a brine electrolysis method employing same.