(229c) A Simple Analytical Model of a Regenerative Hydrogen Bromine Fuel Cell

A Simple Analytical Model of a Regenerative Hydrogen Bromine Fuel Cell

Due to the intermittent nature of renewable power sources, especially wind and solar, and the changing daily requirements of a power grid, energy storage solutions are needed to supplement the primary power sources. One promising option is the so called regenerative fuel cell (RFC). These are reversible fuel cells which store power by performing electrolysis to generate pure components which can then be reacted as fuels in a fuel cell to release the stored power. Hydrogen/oxygen polymer electrolyte membrane (PEM) systems however, suffer from poor performance when operated as a RFC, because of the sluggish oxygen reduction reaction (ORR). One potential way to improve performance on this type of cell is to use hydrogen/bromine PEM-based RFC, because of the much higher reactivity of bromine. A significant advantage of using the hydrogen bromide chemistry, thus, is that the performance of this system is limited by the transport and conductivity properties of the membrane, rather than by electrode kinetics.

To accurately design such RFC systems, it is useful to have a simple analytical model that can accurately describe the electrochemical behavior of a cell based on this chemistry. In this work, we propose a simple model for the H₂/Br₂ reversible fuel cell based on Butler-Volmer kinetics at the electrodes and detailed thermodynamic and transport considerations. The model can accurately predict cell behavior at different operating conditions, such as temperature, fuel concentration, and flowrate, while simplifying and reducing the number of fitted parameters required. An accurate and easily implemented model for a hydrogen bromine fuel cell enables better selection of cell materials and identification of more effective operational modes for power generation and storage.