Nanocrystalline Nickel Hydroxide in Pasted Nickel Electrodes for Rechargeable Nickel Batteries

Nanocrystatline nickel hydroxide powder was modified by the planetary ball milling (PBM), and the physical properties of both the bati-milled and un-milled nickel hydroxides were characterized by scanning electron microscopy, specific surface area (BET), particle size distribution and X-ray diffraction. It was found that the ball milling processing could obviously increase the surface area, break up the agglomeration, decrease the particle and crystallite size, and reduce the crystallinity of beta-Ni(OH)(2), which were advantageous to the improvement of the electrochemical activity of Ni(OH)(2 center dot) The ball-milled nanocrystalline Ni(OH)2 was then used to alter the microstructure of pasted nickel electrodes and improve the distribution of the active material in the porous electrode substrate. Electrochemical performances of pasted nickel electrodes with an addition of ball-mitled Ni(OR)(2) to spherical Ni(OH)(2) as the active material were investigated, and were compared with those of the pure spherical Ni(OH)(2) electrodes. Charge/discharge tests showed that the addition of balt-milled Ni(OR)(2) could enhance the charging efficiency, specific discharge capacity, discharge voltage and high-rate capability of pasted nickel electrodes. This performance improvement could be attributed to a more compact electrode microstructure and lower electrochemical impedance, as indicated by scanning electron microscopy and electrochemical impedance spectroscopy. Thus, it was an effective method to modify the microstructure and improve the electrochemical properties of pasted nickel electrodes by adding an appropriate amount of ball-milled nanocrystalline Ni(OH)2 to spherical Ni(OH)2 as the active material.