Nickel oxyhydroxide/manganese dioxide composite as a candidate electrode material for alkaline secondary cells

Nickel hydroxide and manganese dioxide are used in alkaline cells as positive electrode materials. Positive electrodes comprising a nickel oxyhydroxide/manganese dioxide composite, with modification by Bi₂O₃, deliver a combined reversible discharge capacity of 2.25e per metal atom (650 mAh g⁻¹ metal content), which is higher than that realized from electrodes of either component taken singly. The composite discharges with two potential plateaux, the first appearing at 325 mV corresponds to the discharge of the nickel component, whereas the second at −600 mV is due to the manganese component. Composites of NiO(OH)/MnO₂ can be used as a new electrode material with higher discharge capacity than conventional electrodes.