The Electrochemical Performances of Zn-Al-Hydrotalcites in Zn-Ni Secondary Batteries

Zn-Al-hydrotalcites (Zn-Al-LDHs) are successfully synthesized by a hydrothermal method and a co-precipitation method and are investigated as negative electrode materials for Zn-Ni batteries. Scanning electron microscope (SEM) images, X-ray diffraction (XRD) patterns and laser scattering particle analysis show that the as-prepared sample is flaky in structure and well-crystallized, and the particle sizes are approximately 20-40 mu m. The electrochemical performances of Zn-Al-LDHs determined by different methods are investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge measurements. Compared with pure ZnO powders, Zn-Al-LDHs have good anticorrosion ability. The lower charge platform (1.86 V) and higher discharge platform (1.71 V) of Zn-Al-LDHs indicate that they have better charge/discharge performance as negative active materials for Zn-Ni batteries. These findings show excellent cycle stability in the 40th cycle, with the capacity retention ratio of 81.4% and cycle effciency of approximately 90%, which are much higher than those of pure ZnO (44%).