Size and morphology effects of ZnO anode nanomaterials for Zn/Ni secondary batteries

ZnO nanoparticles and nanorods as anode active materials were investigated by charge-discharge cycle measurements. The ZnO nanomaterials with larger specific surface area exhibited higher electrochemical activity than conventional ZnO particles. The discharge capacity delivered by ZnO nanorods exceeded 500 mA h g(-1) until the 175th cycle. It also exhibited higher midpoint discharge voltage than conventional ZnO. The morphologies of ZnO had a significant effect on the electrochemical properties of the anodes. In the initial cycles, the morphologies of ZnO did not essentially change due to the extension effect, and the electrochemical performance of the electrodes was relatively stable. When increasing the cycles, according to the texture growth mechanism, the large flaky ZnO parallel to the substrate surface predominated to reduce the electrochemical performance. Due to the intensive extension effect, the growth mode of ZnO nanorods changed. The eventual morphology was erect small flaky ZnO crystals that suppressed the production of Zn dendrite and enhanced the capacity maintenance.