Method for making high charging efficiency and fast oxygen recombination

Abstract

The present invention discloses a method to make a high rate, fast oxygen recombination and long life rechargeable metal oxide-hydride batteries, and in particular, rechargeable nickel-hydride batteries. The battery, according to this invention, is composed of a high rate, fast oxygen recombination and long life hydrogen storage electrode as a negative electrode. The hydrogen storage material is prepared to have a thin oxide top surface layer and a metal-rich subsurface layer, especially a nickel-rich subsurface layer. In the microstructure, it is preferable that it consists of a nickel-rich composition in one type of the grains and/or in grain boundaries. The hydride electrode made has an electrochemical capacity from 1.15 to 2.40 AH/cc. Before or after cell assembly, sealing, and/or using, the hydrogen storage electrode is chemically or electrochemically precharged to a state having a half-cell open circuit potential of -0.790 to -0.905 V vs. Hg/HgO reference electrode, and to have an initial charging potential of -0.830 to -1.005 V vs. Hg/HgO reference electrode at a current density of 100 mA/g of active material. The hydrogen storage electrode is composed of at least a hydrogen storage material (alloy), and/or its hydride thereof. The hydrogen storage material consists of nickel and at least five other elements as modifiers; where the atomic mole percent of nickel in the material is greater than 18 at. % but less than 80 at. %, preferably greater than 30 at. % but less than 65 at. %. The modifiers include: (a) at least two hydride formers selected from the group of Ti, Zr, Hf, V, Nb, Ta, Y, Sc, Mg, Ca, Pd, and rare earth metals; (b) at least one de-stabilizing agent selected from the group of Cr, Mn, Fe, Co, Cu, Zn, Mo, Sn, C, B, Sb, Si, Bi Ge, Ga, N, O, and Sn; (c) at least one element selected from the group of corrosion resisting agents selected from the group consisting of Cr, Co, W, Mo, Nb, Hf, and Ta; and (d) at least one element selected from the groups of oxygen getters, catalysts, or the combinations. The oxygen getter is selected from the group consisting of alkali metals, Ca, Al, Sr, Ba, Zr, Hf, Ti, rare earth metals, P, and S. The catalyst is selected from the group consisting Cu, Mn, W, Mo, Pd, Co and O.