Structural characteristics of nickel hydroxide synthesized by a chemical precipitation route under different pH values

The effects of precipitation pH values on the microstructural characteristics of nickel hydroxide material, synthesized by a chemical precipitation method have been studied. The relationship between structural characteristics and electrochemical activity of nickel hydroxide was also examined. The structural characteristics of the synthesized beta-Ni(OH)(2), such as degree of crystallinity, crystalline lattice disorders, crystallite size and crystal growth orientation were strongly related to the pH values of the chemical precipitation reaction. The amounts of SO42-, CO32- and H2O adsorbed in crystals, and the thermal stability of the beta-Ni(OH)(2) also depended on the pH. Under relatively high pH values, the synthesized nickel hydroxide materials possessed a reduced crystallite size and lower thermal stability. more crystalline defects and a higher Ni composition. All these characteristics were likely to improve the electrochemical activity of nickel hydroxide. (C) 2002 Elsevier Science B.V. All rights reserved.