Analysis of performance improvement of hydrogen/bromine flow batteries by using bromate electrolyte

摘要

A H-2/Br-2 flow battery operating with redox-mediated bromate anions (BrO3-) has shown several beneficial features induced by the bromate-bromide chemical reaction, particularly in terms of cell performance and safety issues. In this study, a kinetic model of the chemical reaction is developed by thoroughly accounting for detailed reaction steps and by incorporating a three-dimensional, transient H-2/Br-2 flow battery model. First, the H-2/Br-2 flow battery model with BrO3- is validated against experimental data where cell voltage recovery is observed until the BrO3- is completely consumed. The model successfully reproduces the measured voltage evolution data during discharge, thus accurately capturing the transient behavior of an H-2/Br-2 cell influenced by the bromate-bromide chemical reaction. In addition, H-2/Br-2 cells are simulated with and without BrO3- and model predictions reveal that the reversible voltage, ohmic overpotential in the membrane, and activation overpotential of the Br-2 reduction reaction are all improved due to the use of BrO3- in the catholyte. The present model for the H-2-Br-2-BrO3- system enables the quantitative analysis of the beneficial effects for using redox-mediated bromate anion and thus becomes a useful tool for designing and optimization of H-2/Br-2 cell with BrO3-. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.