Abstract: A hydrogen absorbing alloy electrode is provided which is improved in hydrogen gas absorbing ability and in low-temperature discharge characteristics. The electrode contains a hydrogen absorbing alloy having a crystal structure of the CaCu5 type and represented by the stoichiometric ratio ABx, the hydrogen absorbing alloy being represented by MmNiaCobAlcMd wherein Mm is a misch metal, M is Mn and/or Cu, the atomic ratios a, b, c and d are in the respective ranges of 3.0≦a≦5.2, 0≦b≦1.2, 0.1≦c≦0.9, 0.1≦d≦0.8, wherein X is the sum of the atomic ratios a, b, c, and d, such that, X=a+b+c+d and, is in the range of 4.4≦X≦5.4. More specifically, the electrode contains a hydrogen absorbing alloy powder at least 5.0 in X, and a hydrogen absorbing alloy powder less than 5.0 in X.

Abstract: The method of manufacturing a hydrogen-absorbing alloy electrode comprises: a step of reducing an oxide or hydroxide residing on the surface of a hydrogen-absorbing alloy particle while the alloy particle is held in an atmosphere of a hydrogen gas maintained at a temperature where absorbing of the hydrogen gas does not substantially occur; a step of naturally cooling atmosphere from the temperature where absorbing of the hydrogen gas does not substantially occur to the temperature where the equilibrium hydrogen pressure of the hydrogen-absorbing alloy is equal to the hydrogen pressure in the atmosphere of the hydrogen gas and thereafter vacuum-evacuating the atmosphere of the hydrogen gas so that the hydrogen-absorbing alloy particle is cooled to room temperature while the hydrogen gas is exhausted; a step of exhausting the hydrogen gas and cooling the atmosphere to room temperature and thereafter introducing at least one kind of gas selected from the group consisting of argon, nitrogen and carbon dioxide int

Abstract: The method of manufacturing a hydrogen-absorbing alloy electrode according to this invention comprises the steps of: dissolving a particle surface of said hydrogen-absorbing alloy by a surface-treatment solution; and washing the hydrogen-absorbing alloy with the particle surface dissolved using an alkaline solution at a temperature of 30° C.˜40° C. The metal ions dissolved by the surface-treatment solution can be completely washed away by the alkaline solution so that they will not be precipitated onto the surface of the hydrogen-absorbing alloy again as the hydroxide. In this case, the washing using the alkaline solution of which the temperature exceeds 40° C. dissolves an alloy component as well as the hydroxide. Therefore, the temperature of the alkaline solution used must be controlled at 40° C. or lower. On the other hand, if the temperature of the alkaline solution is lower than 30° C.

Abstract: A hydrogen absorbing alloy electrode characterized in that the electrode consists mainly of a mixture of a first hydrogen absorbing alloy powder A formed on surfaces of particles thereof with a surface layer 22 containing metallic copper or a copper oxide and a second hydrogen absorbing alloy powder B formed on surfaces of particles thereof with a surface layer 24 containing metallic cobalt or a cobalt oxide. The copper-coated hydrogen absorbing alloy powder A affords improved electric conductivity, and the cobalt-coated hydrogen absorbing alloy powder B gives improved ability to absorb and desorb hydrogen, whereby the electrode is improved in different battery characteristics, such as cycle characteristics, high-rate discharge characteristics and infernal pressure characteristics, at the same time.

Abstract: A hydrogen-absorbing alloy electrode for an alkaline secondary battery. The electrode is prepared by adding a transition metal salt to a paste comprising a hydrogen-absorbing alloy powder and binder. The electrode improves charge-discharge cycle performance and high rate discharge capacity at low temperature of an alkaline secondary battery.