Symposium X—MRS/The Kavli Foundation Frontiers of Materials
Symposium SB05: Biohybrid and Soft Functional Interfaces

Symposium EN08: Materials for Emerging Electrochemical Separations

Sofia Kuperman, Technion - Israel Institute of Technology, Israel

Separating Reactants in Membraneless Redox Flow Batteries: Leveraging Fluid Mechanics

Written by Ankita Mathur

Redox flow batteries (RFBs) are a class of emerging electrochemical energy storage technology for grid scale but suffer losses due to the high cost of membranes. “Single flow membraneless RFBs are a viable solution as they contain a single pump and a single electrolyte flow through it,” says Sofia Kuperman of the Technion. Kuperman and co-workers prepared a single flow Zn-Br2 RFBs, wherein they used two solutions with varying densities (called multiphase electrolyte) - one aqueous electrolyte and other polybromide viscous electrolyte. The two solutions form two different phases in same pump-one bromine-poor aqueous continuous phase and the other bromine-rich polybromide phase that forms sedimentation layer and has lower conductivity. Herein, in absence of the membrane, the electrolyte plays an important role in separating the reactants. Kuperman observed that the sedimentation layer has a significant effect on the electrolyte resistance. Lower flow rate causes higher sedimentation at the bottom leading to lower current density and lower efficiency of the battery. She prepared a model, based on fluid mechanics principles, to deeply study the multi-scale flow phenomenon and predicted the flow patterns to decrease the electrolyte resistance to achieve high battery performance in such multiphase single flow RFBs.

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