A method for fabricating lightweight nickel electrodes has been develo
ped by electrochemical impregnation of two different nickel fiber subs
trates. The electrochemical impregnation technique was applied galvano
statically at 35-50 mA/cm(2) in acidic solutions of nickel and cobalt
nitrates (pH = 3). The nickel and cobalt contents of impregnated and f
ormed electrodes was analyzed with atomic absorption spectrometry (AAS
) and the amount of active nickel hydroxide was calculated. NiOOH elec
trode cycle-life performance testing was carried out in alkaline elect
rolyte (4.2-6.9 M KOH, 1 M LiOH) at a similar to C/5 rate during charg
e and discharge. Electrodes based on substrate materials of high poros
ity (90%, FN 090 Nickel Felt, Sorapec) deliver excellent specific capa
cities of 133-145 mAh/g in moderately alkaline electrolyte (4.2 M KOH)
with an active material utilization of 67-95% depending on the quanti
ty of co-precipitated cobalt (1.3-8.3%). NiOOH electrodes using substr
ates with lower porosity (81%, Fibrex 50/50 = fiber/Ni powder, Nationa
l Standard) obtain very stable specific capacities (400 cycles) of 91-
93 mAh/g with a utilization rate of 110% in highly alkaline electrolyt
es (6.9 M KOH).