Effects of surface modification of nickel hydroxide powder on the electrode performance of nickel/metal hydride batteries

Our experimental results show that the electrodeposition of nickel on the s urface of nickel hydroxide particles can increase greatly the conductivity of the nickel hydroxide electrode. Consequently, the capacity of the electr ode is significantly increased. However, there is an optimal point in terms of the amount of deposited nick el. Insufficient nickel would not provide enough conductivity since nickel hydroxide is spontaneously formed and coated on the nickel surface in KOH e lectrolytes. Excessive deposited nickel, on the other hand, would lead to a n increase of charge transfer resistance and decrease of the electrode capa city. The optimal amount of deposited nickel was found to be around 11 wt%, resul ting in the electrode capacity approaching 236 mAh/g Ni(OH)(2) and utilizat ion of active material approaching 82%. In addition, in comparison with electrodes without deposited Ni but contain ing cobalt oxide, the charge efficiency for the electrode with the nickel c oating at elevated temperature was found to be superior. (C) 1999 Elsevier Science Ltd. All rights reserved.