Zn/Br₂ cell: Effects of plated zinc and complexing organic phase

A model is presented for a zinc/bromine cell that considers the effects of an increase or a decrease in the cathode channel width due to zinc removal on discharge and zinc deposition on charge, respectively. The model also includes the effect of an organic bromine complexing agent (OCA) on the cell performance. Changes in the channel width affect the catholyte velocity, cathode side pressure drop, mass transfer and potential drop in the cell, while the inclusion of the bromine complexing organic phase shows a marked effect on the available bromine in the aqueous phase. It is shown that during discharge, the release of complexed Bromine by the OCA could degrade the cell performance. A simple equation is derived and used to express the relationship between the total bromine in the organic phase and the bromine in the aqueous phase.