A NOVEL CELL Design of Alkaline-Based ZINC -Iodide FLOW Battery for Enhancing Energy and POWER Performance

Abstract

An alkaline-based Zinc-Iodide Flow Battery (ZIFB) is considered one of the promising electrochemical energy storage devices with a prospective application in the transport systems due to their high specific energy. To improve the battery performances of this zinc-iodide system, numerous researches have been conducted by considering new materials, electrode structures, various system design and operating conditions. However, there is a very useful prospect to adopt alternative cell geometries that can produce higher power per cell unit volume and/or reduce the overall system cost to commercialize the product. In this work, a novel cell structure is designed for ZIFB, which includes embedded serpentine flow channels in a non-porous and non-brittle case. This new design eliminates end plates and gaskets to improve safety, extend life, and promote ease of assembly with fewer components than traditional ZIFB cells. In particular, a key challenge of conventional graphite flow field plates in which solution penetration can occur due to an easily broken and porous structure is solved by using rigid impermeable polyvinyl chloride (PVC) sheets with flow channels embedded in the sheets. Various tests, such as cycling and polarization measurements of a wide range of current and flow rates, and Electrochemical Impedance Spectroscopy (EIS) for internal resistance analysis, are performed to compare new and traditional designs. The results show that the new design keeps cycling performance stable, with better stability and energy efficiency, than conventional ZIFB cells do. High power performance is also observed for the same external cell size. In addition, an abrupt potential drop caused by high contact resistance between the current collector and a porous electrode is solved by introducing a layer of the patterned graphite sheet to improve contact and electronic conductivity and, also, to function as a flow channel.