Effects of barium on the performance of secondary alkaline zinc electrode

The active material of secondary alkaline zinc electrode with barium additives was prepared by a chemical reaction method and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical performance of various pasted Zn electrodes was investigated by cyclic voltammetry, charge/discharge method and electrochemical impedance spectroscopy (EIS). The addition of barium can synthesize a compound barium zincate with the molecular structure of BaZn(OH)(4)(.)xH(2)O, which turns into another molecular structure of BaZnO2 after heat treatment, and improve the discharge performance. The EIS of the various Zn electrodes show two time constants besides diffusion impedance including a state variable representing the covering degree of ZnO on the electrode surface. (C) 2003 Elsevier B.V. All rights reserved.