Mesoporous yolk-shell ZnO/C microspheres as active ingredient of zinc anode with outstanding cycle stability and high rate performance

Mesoporous ZnO/C microspheres with different morphologies, including solid ZnO/C, yolk-shell ZnO/C, and hollow ZnO/C, are investigated as the active ingredient of the anodic electrode for zinc-nickel batteries. The obtained samples are identified by scanning electron microscope (SEM) or transmission electron microscope (TEM) to confirm the morphology of the three samples we needed and X-ray diffraction (XRD) to determine the presence of impurities. Besides, the specific surface area measured by Brunauer-Emmett-Teller (BET) is one of the pivotal parameters throughout the entire process and is of key importance to the galvanostatic charge-discharge measurements, cyclic voltammograms (CV), tafel curves and electrochemical impedance spectroscopy (EIS) before and after charge-discharge cycles. Yolk-shell ZnO possessing the largest discharge specific capacity of 639.03 mAh g(-1) could be up to 600 mAh g(-1) or more after 535 cycles in virtue of their large surface area and internal voids that could provide the large contact area between the electrode and the electrolyte and effectively alleviate the deformation of the active ingredient. Beyond that, yolk-shell ZnO has outstanding high rate performance compared to solid ZnO and hollow ZnO. (C) 2019 Elsevier B.V. All rights reserved.