Enhancing the Performance of a Zinc-Iodide Redox Flow Battery

Abstract

A very high energy density has been reported for the zinc-iodide flow battery [1]. In order to enhance the performance of a zinc-iodide flow battery, an iodide-based complexing agent (1-cyanomethyl-1-methylpyrrolidinium iodide) was added to a 3.0 M ZnI2 electrolyte system. An optimized flow field design for uniform distribution of the electrolyte is desirable for the redox flow battery systems. The impact of flow field design on the performance of the battery was investigated.Charge-discharge characteristics were carried out to investigate cyclability and efficiency of the zinc-iodide battery with and without the presence of complexing agent. The flow cell used graphite felt electrodes, a Nafion membrane, and had an active area of 5 cm2. In this study, the influence of a flow through design, and a flow-by design on the performance of the zinc-iodide flow battery was evaluated. Electrochemical characterization methods, including cyclic voltammetry (CV) and rotating disk electrode (RDE) studies, with and without the presence of complexing agent were performed to evaluate redox potential, diffusion coefficient and electrochemical reversibility of the electrolyte system. The deposited material on the positive and negative electrodes and stability of the electrode material were studied by SEM, EDX, XRD and Raman.[1]- Li, Bin, Zimin Nie, M. Vijayakumar, Guosheng Li, Jun Liu, Vincent Sprenkle, and Wei Wang. "Ambipolar zinc-polyiodide electrolyte for a high-energy density aqueous redox flow battery." Nature communications 6 (2015): 6303.