Preparation, characteristics and electrochemical performance of Sn6O4(OH)4-coated ZnO for Zn–Ni secondary battery

Sn6O4(OH)4-coated ZnO was successfully prepared by homogeneous precipitation technique based on the hydrolyzation of SnCl2. Transmission electron microscopy (TEM) micrograph and X-ray diffraction (XRD) pattern revealed that Sn6O4(OH)4 was coated on the surface of ZnO particle. Energy dispersive X-ray spectrum (EDS) of Sn6O4(OH)4-coated ZnO showed that the content of coating was about 7 wt%. The electrochemical performance of Sn6O4(OH)4-coated ZnO was investigated by charge/discharge method and slow rate cyclic voltammogram. Compared with pure ZnO and ZnO intermingled with SnO2, Sn6O4(OH)4-coated ZnO showed the largest discharge capacity (557 mAh g−1), the most stable midpoint discharge voltage, the lowest fading rate and charge plateau voltage. XRD pattern of discharged Zn electrode showed that the coating changed irreversibly into Sn and always existed as the form of Sn.