Effect of mechanical milling on structure, morphology and electrochemical performance of zinc oxide powders

ZnO powders were treated by mechanical milling. The structure and morphology of ZnO powders milled for different periods were characterized by XRD and SEM. The discharge behavior and cycle life of ZnO electrodes in Zn/Ni batteries were studied by galvanostatic charge and discharge tests. The incorporation of cycle voltammetry was adopted to investigate charge and discharge mechanisms of ZnO electrodes. The results showed that the grain size of the powders decreased from 135.6 nm to 17.9 nm while the lattice strain increased from 0.06% to 0.57% during milling, which could be attributed to the formation and movement of dislocations. The electrochemical reaction activity of ZnO powders was improved by mechanical milling, resulting in an increase of discharge capacity. ZnO powders milled for 100 h shows a high discharge capacity of 300.6 mAh/g, which is 50 mAh/g higher than that of the unmilled ZnO powders.