Electrochemical performance of three shaped ZnO nanoparticles prepared in LiOH, NaOH and KOH alkaline solutions as anodic materials for Ni/Zn redox batteries

摘要

ZnO nanoparticles with three morphologies were synthesized by a hydrothermal route at 120 A degrees C for 3 h in high alkaline aqueous solutions of LiOH, NaOH, and KOH. We analyzed them by X-ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), cyclic voltammetry (CV), Zeta potential measurement, and impedance. XRD and SEM showed that the obtained ZnO nanoparticles had high purity and perfect crystallinity, and the morphologies of the particles prepared in the LiOH, NaOH, and KOH solutions showed nanoplate, nanobead, and nanorod shapes, respectively. CV showed that the nanoplate ZnO-LiOH and nanorod ZnO-KOH have superior electrochemical activity to that of the other ZnO nanostructures. As electrode materials of Ni/Zn redox batteries, the nanoplate ZnO-LiOH showed a significantly improved cycle stability after the 30 (th) cycle compared to that of ZnO-NaOH and conventional ZnO with a mean discharge capacity of 153 mA h g(-1), a cell efficiency of 93%, and higher discharge voltages of 1.9. In addition, during the charging/discharging cycles, the growth of zinc dendrite clusters could be suppressed, which resulted in an improvement in the cycle stability of the Nianoplate ZnO-LiOH redox cell.