Electrochemical Characteristics of Nickel Hydroxide Fabricated from a Spent Electroless Plating Bath

Electroless nickel plating baths must be replaced periodically to retain the quality of the deposited nickel film, thus resulting in a considerable amount of spent plating solution. In the spent plating solution, Ni2+ of sufficiently high concentration can be reused for energy storage applications. This study investigated a chemical precipitation method that involved adding sodium hydroxide and polyethylene glycol to generate 0.5-mu m Ni(OH)(2) particles. The electrochemical experimental results indicated that an electrode consisting of Ni(OH)(2) and Vulcan XC72 carbon black could provide active sites for charge storage because of the layered structure of the Ni(OH)(2). The interstitial water between the layers enhanced the transport of H+ with a diffusivity of 1.4 x10(-12) cm(2)/s, which was twice as high as that of an electrode made from commercial Ni(OH)(2). Furthermore, a charging-discharging measurement with 100 cycles revealed that the electrode made with Ni(OH)(2) from a spent plating bath exhibited 88% capacitance retention, which was greater than that of the electrode made from the commercial Ni(OH)(2). Consequently, the method proposed in this study may provide usable materials for energy storage while removing nickel from spent plating baths.