HYDROGEN-BROMINE FUEL CELL.
Abstract:
Various problems associated with the construction of practical cells were studied. Platinum, tantalum, niobium and tri or tetrafluoroethylene polymers were found to be acceptable materials of construction. Aqueous HBr was determined to be the best solubilizer for Br2. Properties of HBr-Br2-H2O solutions were investigated in considerable detail. The Br2 solubilized by the HBr was found to act electrochemically mainly as an inert diluent. A special low-water-content ion exchange membrane minimized diffusive attack of Br2 on the anode and permitted cell life to be extended to well over a year. The chemical composition of this membrane could be changed considerably by partial bromination without affecting fuel cell performance the membrane acted primarily as an aqueous permeable membrane with steric hindrance of ions as large as Br-, Br3-, or the like rather than as a true ion exchange barrier. The effective internal resistance of present cells is still high on the order of 8 ohm-sq cm of which about half is directly due to the ion exchange membrane. Author