Miniaturisation of Zn/Br redox flow battery cell and investigation of electrode materials influence on its characteristics

Abstract

Redox flow battery has been paid attention since it has been considered as a solution for large-scale energy storage. Among redox flow batteries, this work focuses on zinc (Zn)/bromine (Br) redox flow battery. The cell of Zn/Br redox flow battery as an energy source for a sensor node of wireless sensor network systems was miniaturised. Here, the fabrication and the experimental results for performance characteristics of the miniaturised Zn/Br redox flow battery cell are reported. Moreover, the electrode materials influence on its characteristics utilising four kinds of carbon materials such as activated carbon, hard charcoal, carbon nanotubes (CNTs), and activated carbon and CNTs composite was investigated. To investigate performance characteristics, charge-discharge tests, impedance measurement, specific surface area measurement, and charge and discharge cycling life test were performed. Moreover, the morphology of electrode materials was observed. As a result, it revealed that the activated carbon electrode showed the best coulombic efficiency of 88.6% and the largest specific surface area. Moreover, it was confirmed that the activated carbon and CNTs composite electrode material has the lowest inherent internal resistance and interfacial resistance among the investigated electrode materials. In the cycling life test, the CNTs electrode showed stable capacity retention during ten cycles.