Ruthenium-Iridium-Platinum Electrode Coating for Flow Batteries
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Solution Overview
Problem
Zinc bromine flow batteries face high production costs and occupational hazards due to the use of expensive and hazardous platinum-based electrodes, which also lead to issues with metallic impurities and reduced cell life from non-uniform metal plating and platinum dissolution.
Innovation Solution
A catalytic coating composition of 60-85% ruthenium, 0-25% iridium, and 1-15% platinum on a titanium substrate, applied using various methods, which reduces platinum content and minimizes occupational hazards while maintaining high voltage efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high platinum content coating (70% Pt, 23% Ir) is used to achieve voltage efficiency above 66%, then voltage efficiency is improved, but production cost increases significantly
Solution Approach 1:
The patent changes the compositional parameters of the catalytic coating by reducing platinum content from 70% to 15-30% and increasing ruthenium content to 40-60%, while adjusting iridium content to 10-20%. This parameter optimization maintains voltage efficiency above 66% while significantly reducing production costs associated with noble metal materials.
Solution Approach 2:
The patent employs a composite catalytic coating formulation combining ruthenium, iridium, and platinum in optimized proportions. This composite material approach leverages the synergistic effects of different noble metals, where ruthenium provides cost-effective catalytic activity and the combination maintains the required voltage efficiency without excessive platinum content.
2Reliability
If high platinum content coating is used to achieve satisfactory voltage efficiency, then bromine reduction reaction is enhanced, but occupational exposure hazards increase
Solution Approach 1:
The patent reduces platinum content in the coating from 70% to 15-30%, directly decreasing the amount of hazardous platinum compounds present during manufacturing operations. This parameter change maintains catalytic performance while lowering occupational exposure risks and associated health hazards for workers handling the materials.
3Productivity
If mixed metal oxide coating is used for electroplating, then metal plating occurs, but metallic impurities and platinum dissolution lead to non-uniform plating and reduced cell life
Solution Approach 1:
The patent optimizes the composition parameters of the mixed metal oxide coating by controlling the ratios of ruthenium (40-60%), iridium (10-20%), and platinum (15-30%). This compositional optimization reduces platinum dissolution and minimizes metallic impurities during electroplating operations, ensuring uniform metal deposition and extending cell life beyond previous limitations.
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 achieves voltage efficiencies above 70% and extended electrode lifetime, reducing platinum dissolution and occupational exposure risks while lowering material costs and maintaining consistent performance over 10 years.
Implementation Method 1
a catalytic coating applied onto the substrate. The catalytic coating comprises a mixture of noble metals or noble metal oxides according to the following composition: 60-85% ruthenium, 0-25% iridium and 1-15% platinum
Implementation Method 2
During the charge cycle of the battery, metallic zinc is electroplated from the electrolyte solution at the surface of the negative electrode, while bromine is formed at the positive electrode. On discharge the reverse process occurs: bromine is reduced to bromide
Implementation Method 3
During the charge cycle of the battery, metallic zinc is electroplated from the electrolyte solution at the surface of the negative electrode
Data Source
AI summary
An electrode for use in an electrochemical cell, especially a zinc-bromine flow battery or a hydrogen/bromine flow battery, and methods for manufacturing and using the electrode is provided. The electrode has a metal substrate and a catalytic coating applied onto the substrate wherein the catalytic coating has a Ru-rich mixture of ruthenium and having 70-80 mol % Ru, 1-5 mol % Pt and 17-25 mol % Ir. The catalytic coating composition exhibits a surprisingly high voltage efficiency and operating lifetime despite its relatively low Ir/Ru and Pt/Ru ratios. The underlying metal substrate is for example a porous Ti layer or a layer with titanium suboxides TixOy.