Effect of Flow-Field Structure on the Performance of Hydrogen/Bromine Redox Flow Batteries

Abstract

A hydrogen/bromine regenerative fuel cell involves complex water and heat transport phenomena during charge and discharge that significantly affect the degree of electrolyte dehydration, electrochemical reactions, proton transport, the concentrations of bromide complexes at the hydrogen electrode, etc. Therefore, developing innovative water and heat management schemes is critical to improve the uniformity of key distributions inside a cell as well as to enhance cell performance and durability. In this work, a three-dimensional, transient, two-phase, non-isothermal hydrogen/bromine fuel cell model is developed by rigorously accounting for two-phase transport and various heat generation mechanisms including irreversible heat, entropic heat, and Joule heating. The model is applied to a 25 cm2 cell in order to precisely investigate water transport and thermal aspects under various charge and discharge conditions. A parallel computing methodology is employed to handle large-scale simulations involving millions of grid points. The large-scale simulations are able to provide extensive multidimensional contours of species concentration, temperature, and current density, assisting in identifying optimal water and thermal management strategies based on a typical geometry of a real-scale hydrogen/bromine cell.