Characterization of cobalt-dipped nickel electrodes with fibrex substrates

Nickel electrodes using fibrous substrates have poorer initial utilization of the active material than those using conventional nickel sinter substrates. Previous investigators had shown that utilization can be dramatically improved by dipping these electrodes in a cobalt solution immediately after the electrochemical impregnation, before formation and cycling is carried out. The present study looked at the gas evolution behavior of dipped and undipped electrodes, impedance curves, and the charge-discharge curves to try to understand the reasons for the improvement in utilization. Impedance measurements under open circuit conditions indicate that some of the improvement is due to a reduction in the ohmic resistance of the surface layer of the particles, in agreement with earlier work. The charge-discharge curves suggest that there may also be an additional increase in the ohmic resistance of the surface layer of the undipped electrode during charging