Preparation and electrochemical properties of ZnO/conductive-ceramic nanocomposite as anode material for Ni/Zn rechargeable battery

A novel ZnO/conductive-ceramic nanocomposite was prepared by a homogeneous precipitation between Zn(NO3)(2) and CO(NH2)(2) with conductive ceramic powders as the nucleation sites. The conductive ceramic powders contained zinc oxide, bismuth oxide, cobalt oxide and rare earth oxide, and the nominal chemical composition (mole fraction) was represented by (ZnO)(0.92)(Bi2O3)(0.054)(Co2O3)(0.02.5)(Nb2O5)(0.00075)(Y2O3)(0.00025). The phase composition and surface morphology of the as-synthesized materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). ZnO nanorods with the length of about 200 nm were dispersed homogeneously on the surface of the conductive ceramic, and Identified as a well-defined single-phase hexagonal structure. The electrochemical properties of the ZnO/conductive-ceramic nanocomposite as anode material of Ni/Zn battery were investigated by charge/discharge cycling test, slow rate cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Compared with pure nanosized ZnO, the ZnO/conductive-ceramic nanocomposite showed better cycling stability, higher discharge capacity and utilization ratio. The initial discharge capacity of ZnO/conductive-ceramic nanocomposite reached about 644 mAh g(-1). The discharge capacity hardly declined over 50 cycling tests, and the average utilization ratio could reach 99.5%. EIS revealed that the charge-transfer resistance was lower than that of pure nanosized ZnO. (C) 2008 Elsevier B.V. All rights reserved.