Effects of coprecipitated zinc on the structure and electrochemical performance of Ni/Al-layered double hydroxide

The effects of zinc on the structure and electrochemical performance of Ni/Al-layered double hydroxides (LDHs) prepared by a coprecipitation method were studied. The experimental results showed that the addition of zinc in Ni/Al-LDHs improved the electrochemical performance of the samples such as discharge potential, cycle stability and reversibility. The maximum specific discharge capacity of 425 mAh g(-1) of nickel hydroxide was obtained for the Ni/Al-LDHs without zinc. The maximum discharge mediate potential of 413 mV and the lowest capacity deterioration rate of < 5% after 398 charge-discharge cycles at 1C rate were gained for the 6.4 wt% Zn-containing sample. The results of electrochemical impedance spectroscopy and powder X-ray diffraction measurements indicated that the advantageous performance of Ni/Al-LDHs with high zinc content resulted from the decrease of electron transfer resistance (R-t) and the number of cells per crystallite in the direction of c-axis and slow dissolution of zinc in alkaline solution. (C) 2002 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.