Effect of Cobalt Additive on the NiOOH/Ni(OH)(2) Phase Boundary Movement

Abstract

Effect of cobalt additive on the NiOOH/Ni(OH)(2) phase boundary movement has been investigated by analysing build-up and decay current transients under the application of various voltage steps(70 to 400 mV). The occurrence of current plateau upon hydrogen extraction from the completely hydrogen-injected film indicated that the hydrogen transport through the film proceeds by the movement of NiOOH/Ni(OH)(2) phase boundary. The velocity and mobility of the phase boundary movement upon hydrogen extraction were determined to be orders of 10(-6) an s(-1) and 10(-5) cm s(-1) V(-1) in magnitude, respectively. It is concluded that beta-Ni(OH)(2) phase is stabilised by the Co(OH)(2) incorporaton into the Ni(OH)(2) film and hence both the velocity and mobility of the NiOOH/Ni(OH)(2) phase boundary movement is raised by the Co(OH)(2) incorporation.