Flow field design and visualization for flow-through type aqueous organic redox flow batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous organic redox flow batteries (AORFBs) offer high-performance energy storage due to fast organic electrolyte kinetics.
• Mass transport limitations in AORFBs hinder performance, especially with conventional flow fields designed for inorganic electrolytes.
• Severe cell polarization can occur when using standard flow fields, compromising AORFB efficiency.

Purpose of the Study:

• To design and optimize a flow field for flow-through type AORFBs.
• To enhance uniform electrolyte distribution and flow within porous electrodes.
• To overcome mass transport limitations and reduce cell polarization in AORFBs.

Main Methods:

• Utilized three-dimensional multiphysics simulation for flow field design.
• Employed operando imaging to visualize electrolyte flow dynamics.
• Fabricated and tested a prototype pH-neutral TEMPTMA/MV cell with the optimized flow field.

Main Results:

• The optimized flow field features multistep distributive channels and point-contact blocks for uniform flow.
• Significantly reduced local concentration overpotentials were observed.
• Achieved a peak power density of 267.3 mW cm⁻² in a prototype TEMPTMA/MV cell.
• Enabled charging at current densities up to 300 mA cm⁻², surpassing conventional designs.

Conclusions:

• The designed flow field is crucial for improving AORFB performance by addressing mass transport limitations.
• The study highlights the importance of cell stack engineering in AORFB development.
• The visualization method provides valuable insights for future aqueous flow battery designs.