LAUSR

Abstract A H2/Br2 flow battery operating with redox-mediated bromate anions ( BrO 3 − ) 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 H2/Br2 flow battery model. First, the H2/Br2 flow battery model with BrO 3 − is validated against experimental data where cell voltage recovery is observed until the BrO 3 − is completely consumed. The model successfully reproduces the measured voltage evolution data during discharge, thus accurately capturing the transient behavior of an H2/Br2 cell influenced by the bromate-bromide chemical reaction. In addition, H2/Br2 cells are simulated with and without BrO 3 − and model predictions reveal that the reversible voltage, ohmic overpotential in the membrane, and activation overpotential of the Br2 reduction reaction are all improved due to the use of BrO 3 − in the catholyte. The present model for the H 2 - Br 2 - BrO 3 − 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 H2/Br2 cell with BrO 3 − .