Lightweight nickel electrodes for nickel/hydrogen cells

Thick nickel electrodes with lightweight substrate material have been prepared and tested in Ni/H 2 boilerplate cells containing 26% KOH electrolyte. Lightweight substrates used in this study were either 85 or 90% in porosity and either 0.8 or 2 mm in thickness, respectively, compared with 80 to 82% porosity and 0.75 to 0.8 mm thickness of the state-of-the-art sintered plaque substrate. All of these thick electrodes had substantially improved theoretical (or chemical) capacity over that of state-of-the-art sintered nickel plaque electrodes. However, utilization of the active material was low (65 to 80%) compared with that of the state-of-the-art electrodes (approximately 90%) in 26% KOH. Due to this low utilization, the electrodes using 85% porous substrates did not show any advantage over the state-of-the-art ones. The electrodes using a 90% porous substrate, however, showed 17% higher usable specific capacity (about 0.13 Ah/g in 26% KOH) than that of the state-of-the-art nickel electrodes despite the low utilization. These electrodes achieved up to 4860 cycles at 40% depth-of-discharge with neither capacity loss nor any significant changes of rate capability and charging efficiency with cycling.