Development of advanced stack materials for the Zinc/Bromine redox flow battery

Abstract

The zinc/bromine redox flow battery is one of the promising energy storage systems for energy storage systems due to the lower cost and its higher energy density compared with other kinds of RFBs. In this study, core cell stack materials were investigated in order to improve the cell performance of zinc/bromine redox flow battery. First, a combination of homo polypropylene, CNT, and other carbon fillers for an electrode for the zinc/bromine redox flow battery was studied. Testing of this battery showed improved electrical conductivity, mechanical properties, and charge-discharge performance compared with conventional carbon-based electrodes. The result showed that a zinc/bromine redox flow battery equipped with the polypropylene carbon composite electrode with an optimum CNT content has a better performance and is more suitable than other carbon composite materials for bipolar plate of a zinc/bromine redox flow battery. Second, the new slurry coating method for cathode activation layer of the zinc/bromine redox flow battery was investigated. A higher active surface area is required for the bromine-side electrode because the overall process of bromine-side is slower than zinc-side reactions. The results showed that the new slurry coating method has successful results to improve the long term stability and the charge-discharge performance compared to the conventional coating method. In addition, new slurry coating method can be applied for the mass industrial production when commercialization. Lastly, the coated separator of the zinc/bromine redox flow battery was investigated in order to decrease bromine diffusion and increase durability resulting in the improvement of the performance of the zinc/bromine redox flow battery. As a result, it is suggested that the silica coating on the separator is a promising potential to improve the performance of the zinc/bromine redox flow battery.