Multilayer Oxygen-Consuming Electrode for Chlor-Alkali Cells
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing oxygen-consuming electrodes in chlor-alkali electrolysis and fuel cells face challenges with liquid and gas breakthrough, leading to inefficiencies and high cell voltages due to their sensitivity and thickness, which complicates their use in technical electrolysers.
Innovation Solution
A multilayer oxygen-consuming electrode with varying catalyst and PTFE concentrations between the gas and electrolyte sides, produced using a wet process, ensures high tightness and thinness, allowing for efficient gas and liquid management and reduced cell voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer oxygen-consuming electrode is used, then the structure is simple and manufacturing is easy, but the electrode shows sensitivity to liquid and gas breakthrough requiring greater thickness
Solution Approach 1:
The electrode is divided into multiple layers with different PTFE concentrations. The first layer (gas side) has higher PTFE content for gas tightness, while the second layer (electrolyte side) has lower PTFE content for electrolyte permeability. This segmentation allows each layer to perform its specific function optimally, achieving both liquid and gas breakthrough prevention without requiring excessive thickness.
Solution Approach 2:
Different regions of the electrode are given different properties through varying PTFE concentrations. The gas-facing layer has high PTFE content (5-20 wt.%) for hydrophobicity and gas barrier properties, while the electrolyte-facing layer has low PTFE content (1-5 wt.%) for hydrophilicity and electrolyte transport. This local quality differentiation resolves the contradiction between tightness and permeability.
2Reliability
If the electrode is made thicker to prevent liquid and gas breakthrough, then tightness improves, but cell voltage increases
Solution Approach 1:
By segmenting the electrode into functional layers, each optimized for its specific task, the total thickness required to achieve breakthrough prevention is reduced compared to a uniform single-layer design. This segmentation allows the electrode to achieve the necessary tightness with minimal thickness, thereby reducing ohmic resistance and cell voltage.
Solution Approach 2:
The PTFE concentration parameter is varied across different layers to optimize performance. The gradient in PTFE content (higher at gas side, lower at electrolyte side) creates optimal transport properties for both gas and electrolyte, reducing resistance to mass transport and lowering the overall cell voltage while maintaining breakthrough prevention.
3Ease of manufacture
If uniform PTFE concentration is used throughout the electrode, then manufacturing is simplified, but the electrode cannot simultaneously achieve gas tightness and electrolyte permeability
Solution Approach 1:
The electrode is segmented into distinct layers, each with uniform but different PTFE concentrations. This segmentation allows each layer to be manufactured with consistent properties while the overall electrode achieves the complex dual functionality required for simultaneous gas tightness and electrolyte permeability.
Solution Approach 2:
The electrode structure implements local quality by assigning different PTFE concentrations to different spatial regions. The gas-facing layer has high PTFE for gas barrier properties, while the electrolyte-facing layer has low PTFE for electrolyte transport. This local differentiation enables the electrode to perform both functions simultaneously without compromising manufacturing feasibility.
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 multilayer structure achieves improved tightness against liquid and gas breakthrough, enabling lower cell voltages and enhanced performance in electrolytic cells, with cell voltages as low as 2.0 V at 4 kA/m², while maintaining mechanical stability and electrical conductivity.
Implementation Method 1
The hydrophobic components make it difficult for electrolytes to penetrate and thus keep the corresponding pores free for the transport of oxygen to the catalytically active centers
Implementation Method 2
The hydrophilic components enable the electrolyte to penetrate to the catalytically active centers and transport the hydroxide ions away
Implementation Method 3
The paste is then applied to a flow distributor via screen printing or calendering, while the less viscous suspension is usually sprayed on
Implementation Method 4
A thickener can be added to the suspension to make it easier to process. The paste is then applied to a flow distributor via screen printing or calendering
Implementation Method 5
After excess dispersing agent has been removed, the paste or suspension is gently dried and pressed at temperatures in the range of the melting point of the polymer
Implementation Method 6
After excess dispersing agent has been removed, the paste or suspension is gently dried and pressed at temperatures in the range of the melting point of the polymer
Data Source
AI summary
An oxygen-consuming electrode, particularly for use in chlor-alkali electrolysis, with a novel catalyst coating and an electrolysis device are described. The oxygen-consuming electrode is a multilayer electrode for oxygen reduction in aqueous alkaline media, comprising at least one support, which is particularly electrically conductive, a catalyst-containing layer, and a hydrophobic layer. The electrode has a side facing the oxygen-containing gas and a side facing the alkaline electrolyte. The electrode has at least two different catalyst-containing layers with different catalyst contents, and the outermost layer facing the gas side has a lower catalyst content than the outermost layer facing the electrolyte. The hydrophobic material content in the hydrophobic layer is a maximum of 8% by weight.Furthermore, a manufacturing process for the oxygen consumption electrode and its use in chlor-alkali electrolysis or fuel cell technology are described.