Zinc Electrode Morphology Evolution in High Energy Density Nickel-Zinc Batteries

Abstract

Prismatic Nickel-Zinc (NiZn) batteries with energy densities higher than 100 Wh kg −1 were prepared using Zn electrodes with different initial morphologies. The effect of initial morphology of zinc electrode on battery capacity was investigated. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) reveal that initial morphology of zinc electrode changes drastically after a few charge/discharge cycles regardless of initial ZnO powder used. ZnO electrodes prepared using ZnO powders synthesized from ZnCl 2 and Zn(NO 3 ) 2 lead to average battery energy densities ranging between 92 Wh kg −1 and 109 Wh kg −1 while using conventional ZnO powder leads to a higher energy density, 118 Wh kg −1 . Average discharge capacities of zinc electrodes vary between 270 and 345 mA g −1 , much lower than reported values for nano ZnO powders in literature. Higher electrode surface area or higher electrode discharge capacity does not necessarily translate to higher battery energy density.