Reaction Kinetics and Mass Transfer Synergistically Enhanced Electrodes for High-Performance Zinc-Bromine Flow...

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Zinc-bromine flow batteries (ZBFBs) are promising for grid-scale energy storage due to high energy density and cost-effectiveness.
• Conventional ZBFBs face challenges with non-uniform zinc deposition and slow Br₂/Br^- redox kinetics, limiting cycle life and power density.

Purpose of the Study:

• To develop a novel multiscale porous electrode for ZBFBs.
• To address challenges of inhomogeneous zinc deposition and sluggish redox kinetics.
• To enhance the performance and commercial viability of ZBFBs.

Main Methods:

• In situ growth of zeolitic imidazolate framework-8 on graphite felts.
• Facile carbonization process to create nitrogen-containing functional groups.
• Characterization using theoretical and experimental analyses.

Main Results:

• Nitrogen-containing functional groups promote uniform zinc deposition via high adsorption energy and improved mass transport.
• The electrode significantly boosts Br₂/Br^- reaction kinetics due to high catalytic activity and large surface area.
• Optimized ZBFBs achieved ultrahigh current density (250 mA cm^-2) with 68.0% energy efficiency, outperforming pristine electrodes (50.7%).

Conclusions:

• The developed electrodes effectively tackle critical challenges in ZBFBs, improving zinc deposition and redox kinetics.
• ZBFBs with optimized electrodes demonstrate exceptional cycling stability over 2000 cycles.
• This approach offers a viable strategy for high-performance ZBFB electrodes, advancing commercialization.