Gas Diffusion Electrode Hydrophilic Layer for Chlor-Alkali Voltage Reduction
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Solution Overview
Problem
Conventional oxygen-consuming electrodes in chlor-alkali electrolysis face issues with high operating voltage, gas permeability, and mechanical stability, leading to performance degradation and increased cell voltage due to oversized hydrophilic pores and cracks, which compromise the seal and catalytic activity.
Innovation Solution
Applying a finely divided hydrophilic component with an average particle diameter of 20-100 nm, preferably 40-80 nm, on the liquid-facing side of the electrode to reduce pore diameters and create additional catalytically active centers, enhancing the seal and reducing operating voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional gas diffusion layer with catalyst is used, then catalytic activity is achieved, but oversized hydrophilic pores and cracks cause gas permeability issues and compromised sealing
Solution Approach 1:
The patent applies a hydrophilic porous layer with controlled pore structure to the gas diffusion layer. This layer has pores sized to allow liquid transport while blocking gas penetration, thereby achieving gas tightness without compromising the underlying catalytic functionality. The porous structure is specifically designed with pore diameters that prevent gas bubble formation and migration.
Solution Approach 2:
The patent creates a composite structure by combining the existing gas diffusion layer with catalyst particles and PTFE binder with an additional hydrophilic porous layer. This composite approach allows the system to simultaneously maintain gas diffusion properties, catalytic activity, and improved gas tightness through the synergistic combination of different material layers with complementary functions.
2Ease of manufacture
If the electrode structure is simplified, then manufacturing is easier, but mechanical stability and performance degradation resistance are reduced
Solution Approach 1:
The patent applies the hydrophilic porous layer during the manufacturing process before the electrode is put into operation. This preliminary action ensures that the gas tightness improvement is built into the electrode structure from the beginning, preventing performance degradation that would otherwise occur during operation due to gas bubble accumulation and mechanical stress.
3Speed
If hydrophobic PTFE is used for gas diffusion, then gas transport is enabled, but caustic soda can block pores or crystallize, reducing long-term stability
Solution Approach 1:
The patent introduces a distinct hydrophilic porous layer with different local properties (hydrophilic rather than hydrophobic) between the gas diffusion layer and the liquid environment. This local quality change creates a dedicated liquid transport pathway that prevents caustic soda from blocking the hydrophobic PTFE pores, thereby maintaining gas transport functionality while improving long-term stability against chemical degradation.
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 approach significantly improves the gas tightness and reduces operating voltage by accumulating finely divided hydrophilic particles on the electrode surface, increasing catalytic activity and maintaining liquid transport while reducing gas penetration into the liquid phase.
Implementation Method 1
a suspending agent which can be removed by evaporation is applied
Implementation Method 2
the free area of the pore opening is reduced. The pore can hold the liquid better, and it is more difficult for oxygen to penetrate into the liquid phase
Implementation Method 3
a catalytically active component... which catalyzes the reduction of oxygen
Implementation Method 4
the solid, electron-conducting catalyst initiates an electrochemical reaction between the liquid and the gaseous phase catalyzed
Data Source
Figure 1~2
AI summary
Oxygen-consuming electrode comprises at least one carrier in form of a sheet, and a coating with a gas diffusion layer and a catalytically active component. A one side of the oxygen-consuming electrode, faces the liquid or an ion exchange membrane during operation. The electrode further comprises a finely divided hydrophilic component with an average particle diameter of 20-100 nm, preferably 50-70 nm. An independent claim is also included for preparing the oxygen-consuming electrode, comprising applying or spraying the finely divided, hydrophilic component in a form of suspension (0.1-50 wt.%, preferably 1-20 wt.%) on a planar raw electrode, and removing the suspending agent by evaporation.