The composite of ZnSn(OH)6 and Zn–Al layered double hydroxides used as negative material for zinc–nickel alkaline batteries

Abstract

A series of Zn–Al layered double hydroxides (LDHs) and ZnSn(OH)6 composites were successfully synthesized by hydrothermal method. The characteristic diffraction peaks of composites analyzed by X-ray diffraction (XRD) display that Zn–Al LDHs have been coupled with ZnSn(OH)6, among which the composite containing 10% ZnSn(OH)6 shows the best crystallinity. Besides, scanning electron microscopy (SEM) was conducted to observe the crystal morphologies. The electrodes were carried out by electrochemical measurements such as cyclic voltammograms (CV), electrochemical impedance spectroscopy (EIS), and cycling performance. The results suggest that the discharge specific capacity of composite containing 10% ZnSn(OH)6 is basically kept at 354 mAh g−1 with a capacity retention rate about 98.3% after 800 cycles. Meanwhile, the CV measurement manifests that this material has the smallest redox peak potential difference (0.31 V) than that of others. And the electrode reaction of composite containing 10% ZnSn(OH)6 occurs easily because the EIS test implies that its charge transfer resistance has been declined by 11.57 Ω cm2, accompanied by the ohmic resistance decreasing by 0.48 Ω cm2. The findings mentioned above can be attributed to the high electron mobility and electrical conductivity of ZnSn(OH)6. All the results show that the electrode of LDHs with 10% ZnSn(OH)6 has quite outstanding electrochemical performances when used as the negative material for zinc–nickel alkaline batteries.