Redox flow battery with mixing plates inserted into porous electrodes

Redox flow battery with reduced concentration gradients in electrodes via high-porosity mixing zones

This technology features a redox flow battery structure that incorporates mixing zones with high porosity or permeability into the active material flow paths within porous electrodes. This reduces active material concentration gradients and lowers reaction overpotential.

Scaling up redox flow batteries or operating them at high current densities has historically led to non-uniform active material concentrations within porous electrodes as reactions progress. This results in increased overvoltage and reduced energy efficiency.

This technology utilizes multiple porous flow electrodes spaced apart, with empty spaces or high-porosity media acting as mixing zones between them. This ensures that the active material, having reacted while passing through an electrode, is fully mixed before entering the next. Applicable to MW-scale vanadium flow battery stacks, zinc-bromine flow batteries, and organic flow cell designs, it prevents the accumulation of voltage loss even with larger electrode areas, thereby expanding the high-current operating range.

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Key Features:

• First and second flow electrodes separated by an ion-exchange membrane, implemented as porous media, and arranged with a gap
• Mixing zones formed as empty spaces or porous media between multiple flow electrodes along the active material flow path
• First and second mixing zones containing sections with higher porosity or permeability than the flow electrodes in the direction of active material flow
• An electrode unit that reduces concentration gradients in the direction of current by passing the entire reacted active material through the mixing zone without additional electrolyte inflow

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This invention was developed with support from the Ministry of Trade, Industry and Energy for the development of asymmetric composite bipolar electrodes and stack technology with integrated flow channels for zinc-bromine flow batteries.

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