Abstract: In a positive electrode active material for alkaline storage batteries according to the present invention, a surface of a nickel hydroxide is coated with a mixed crystal material of at least one type of element selected from aluminum Al, manganese Mn, iron Fe, yttrium Y, ytterbium Yb, erbium Er, and gadolinium Gd and cobalt, the valence of nickel in the nickel hydroxide is in the range of 2.0 to 2.3, and the valence of cobalt in the mixed crystal material exceeds 3.0. The positive electrode active material for alkaline storage batteries is used for a positive electrode for alkaline storage batteries, and the positive electrode for alkaline storage batteries is further used for an alkaline storage battery.

Abstract: A hydrogen storage alloy electrode for a battery is made of a hydrogen storage alloy powder which includes agglomerates of hydrogen storage alloy particles joined together through a metallic layer. A method of making the electrode includes forming agglomerates of hydrogen storage alloy particles joined together by a metallic layer which covers surface portions of the particles, and then forming the electrode using a resulting powder including the agglomerates.

Abstract: An object of the present invention is to provide an effective hydrogen-absorbing alloy activation process which can enhance the electrochemical activity of a hydrogen-absorbing alloy and to provide a hydrogen-absorbing alloy electrode which, when used in a battery, ensures an excellent initial inner pressure characteristic, low-temperature discharge characteristic, high-rate discharge characteristic and cycle characteristic. In accordance with the present invention, a hydrogen-absorbing alloy electrode production process is provided which comprises an alloy activation treatment step of immersing a hydrogen-absorbing alloy in a strong acid treatment solution containing metal ions and, in the course of the pH rise of the acid treatment solution, adding an alkali to the acid treatment solution to promote the pH rise of the acid treatment solution.

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.

Abstract: The invention provides a hydrogen absorbing alloy electrode obtained by the step P1 of preparing a hydrogen absorbing alloy powder containing cobalt and nickel, the step P2 of subjecting the surfaces of the alloy particles to a reduction treatment with high-temperature hydrogen by holding the powder in a high-temperature hydrogen atmosphere under the conditions of temperature, pressure and time sufficient to reduce oxides formed in a surface layer portion of each of the alloy particles, not melting the alloy particles and not permitting the alloy particles to absorb hydrogen, the step P3 of treating the resulting powder with an acid or alkali by immersing the powder in an acid or alkaline aqueous solution, followed by suction filtration, washing with water and drying, and the step P4 of applying the resulting power to an electrically conductive substrate and shaping the substrate in the form of the electrode. The electrode thus provided has higher activity than conventionally.

Abstract: A hydrogen-absorbing alloy electrode for an alkaline secondary battery. The electrode is made from a hydrogen-absorbing alloy containing nickel which has been treated with an acidic solution containing a chelating agent for nickel. The hydrogen-absorbing alloy electrode has good activity and a nickel-hydrogen battery having the hydrogen-absorbing alloy electrode as a negative electrode has a large high rate discharge capacity soon after being assembled, and inhibits an increase of internal pressure during discharge.

Abstract: The hydrogen-absorbing alloy electrode for alkaline storage batteries according to the invention comprises a hydrogen absorbing alloy powder prepared by grinding a strip of hydrogen absorbing alloy produced by solidifying a molten alloy by a roll method and satisfying the following relations:r/t.ltoreq.0.5 (1)60.ltoreq.t.ltoreq.180 (2)30.ltoreq.r.ltoreq.90 (3)wherein r represents the mean particle size (.mu.m) of the hydrogen absorbing alloy powder and t represents the mean thickness (.mu.m) of the strip absorbing alloy. The hydrogen absorbing alloy electrode of this invention features an improved high-rate discharge characteristic at low temperature.

Abstract: In the present invention, a hydrogen absorbing alloy treated upon immersed in an acid solution containing at least a quinone compound, a hydrogen absorbing alloy immersed in water to which at least a quinone compound is added, or a hydrogen absorbing alloy treated upon being immersed in an acid solution containing at least a quinone compound and then immersed in water to which at least a quinone compound is added is used for a hydrogen absorbing alloy electrode, and the hydrogen absorbing alloy electrode is used as a negative electrode of an alkali secondary battery.

Abstract: In the present invention, a hydrogen absorbing alloy containing at least nickel, cobalt and aluminum, in which the sum a of the respective abundance ratios of cobalt atoms and aluminum atoms in a portion to a depth of 30 .ANG. from its surface and the sum b of the respective abundance ratios of cobalt atoms and aluminum atoms in a bulk region inside thereof satisfy conditions of a/b.gtoreq.1.30, or a hydrogen absorbing alloy containing at least nickel, cobalt, aluminum and manganese, in which the sum A of the respective abundance ratios of cobalt atoms, aluminum atoms and manganese atoms in a portion to a depth of 30 .ANG. from its surface and the sum B of the respective abundance ratios of cobalt atoms, aluminum atoms and manganese atoms in a bulk region inside thereof satisfy conditions A/B.gtoreq.1.20 is used for a hydrogen absorbing alloy electrode in an alkali secondary battery.

Abstract: A hydrogen-absorbing alloy electrode for metal hydride alkaline batteries uses as hydrogen-absorbing material a powder of a rare earth element-nickel hydrogen-absorbing alloy obtained by pulverizing thin strips of said alloy prepared by single roll process and having an average thickness of 0.08 to 0.35 mm and a minimum size of crystal grains present in the roll-surface size of at least 0.2 .mu.m and a maximum size of crystal grains in the open-surface side of not more than 20 .mu.m. A process for producing the above electrode is also provided. The electrode can provide, when used as negative electrode, metal hydride alkaline batteries which are excellent in both high-rate discharge characteristics at an initial period of charge-discharge cycles and charge-discharge cycle characteristics.

Abstract: A hydrogen-absorbing alloy electrode for metal hydride alkaline batteries is obtained by coating or filling a collector with a hydrogen-absorbing alloy powder consisting essentially of spherical particles and/or nearly spherical particles and then sintering the powder, the powder having an average particle diameter of 30 to 70 .mu.m and containing 5 to 30% by volume of particles having a diameter of at least 2 times the average diameter and 10 to 40% by volume of particles having a diameter of not more than 1/2 of the average diameter. This electrode can give metal hydride alkaline batteries having excellent high-rate discharge characteristics and a long life.