Formation of porous ZnO microspheres and its application as anode material with superior cycle stability in zinc-nickel secondary batteries

Porous ZnO microspheres and globular ZnO are synthesized by facile hydrothermal methods and the electrochemical performance as negative active ingredient of zinc-nickel secondary battery is compared with commercial ZnO. Throughout the process, we first characterize the material by X-ray diffraction (XRD) to confirm the samples and the morphology of the samples before and after charge-discharge process is determined by scanning electron microscope (SEM). Also, Brunauer-Emmett-Teller (BET) measures the specific surface area which plays a vital role in the galvanostatic charge-discharge measurements, cyclic voltammograms (CV) and electrochemical impedance spectroscopy (EIS). Porous ZnO whose maximum discharge specific capacity is up to 643.2 mAh g−1 (coulomb efficiency 97.60%) has outstanding cycling performance and large discharge capacity due to the porous structure and the large specific surface area, and the specific capacity remains essentially above 600 mAh g−1 in the first 600 cycles after the pre-activation process. In addition, the high rate performance of porous ZnO is also examined to demonstrate that porous ZnO as negative active ingredient of zinc-nickel secondary battery has good discharge properties under a large current density.