Flow-Through Design for Enhanced Redox Flow Battery Performance

Abstract

The high capital cost, driven by the poor performance, still hinders the widespread application of vanadium redox flow batteries. This work compares two different cell designs to demonstrate that the electrolyte flow velocity and pattern is of critical importance to increase the overall battery performance. The Oriented-Distribution-Path (ODP) cell design includes inlet and outlet distribution channels, while the Multi-Distribution-Path (MDP) design does not. The introduction of the distribution channels in the ODP caused the electrolyte flow pattern through the electrode to be less uniform. However, the latter reduced the concentration polarization under high current density and low flow rate conditions. In a charge-discharge cycle comparison, the MDP displayed the highest cell energy efficiency at 80 mA cm−2 and at a flow rate of 300 cm3 min−1. However, the best overall performance was obtained using the ODP at 80 mA cm−2 and a flow rate of 10 cm3 min−1. This work demonstrates that the highest system energy efficiency is achieved when using low flow rates together with a cell design that promotes a high pressure drop. The insights of this study apply to other chemistries making it useful to define guidelines for designing energy-efficient redox flow batteries.