Modeling the Effect of the Operating Temperature on the Performance of a Zinc/Bromine Flow Battery

Abstract

The zinc/bromine (Zn/Br2) flow battery is an attractive rechargeable system for energy storage because of its inherent chemical simplicity, high degree of electrochemical reversibility at the electrodes, good energy density, and abundant low-cost materials. Because the performance of a Zn/Br2 flow battery depends strongly on the operating temperature, it is important to develop a mathematical model to predict the performance of the battery as a function of the operating temperature in order to estimate such quantities as current efficiency and conversion per pass. This information can be used to design both of bench and production scale cells and to select the operating conditions for optimum performance. In this work, a method of modeling the dependence of the charge and discharge curves of a Zn/Br2 flow battery on its operating temperature is presented. This work adopts a simple modeling approach by considering Ohm’s law and charge conservation on the electrodes based on the simplified polarization characteristics of the electrodes. To accommodate the temperature dependence, the key modeling parameters are expressed as the functions of temperature based on the well-known principles of the Arrhenius equation of chemical kinetics and the Nernst equation of electrochemical thermodynamics. The model is validated by comparing the modeling results with the experimental measurements.