Abstract: A method of producing a hydrogen storage alloy, for use in alkaline storage batteries, includes two steps. A first step involves preparing alloy particles having a CaCu5-type crystal structure and the compositional formula MmNixCoyMnzM1?z, wherein M represents at least one element selected from the group consisting of aluminum (Al) and copper (Cu), 3.0?x?5.2, 0?y?1.2, 0.1?z?0.9, and 4.4?x+y+z?5.4. A second step involves immersing the alloy particles in an acid treating solution containing a cobalt compound and a copper compound, each in the amount of 0.1 to 5.0% by weight based on the weight of the alloy particles, and an organic additive to remove oxide films from and to reductively deposit cobalt and copper on a surface of each alloy particle to form a surface region surrounding a bulk region and having a graded composition. When the sum in percentage of numbers of cobalt (Co) atoms and copper (Cu) atoms present in the surface region is given by a and that in the bulk region by b, the relationship a/b?1.

Abstract: With an alkaline storage battery according to the invention, a coating layer of a cobalt compound is provided on the surface a cathode active material composed mainly of nickel hydroxide, and at least one species of compound selected from the group consisting of a niobium compound, titanium compound, tungsten compound and molybdenum compound is added to the coating layer of the cobalt compound while an alkaline electrolytic solution contains lithium hydroxide, and a lithium hydroxide content is not less than 0.6 mol/L and not more than 1.6 mol/L.

Abstract: After coating a hydrogen absorbing alloy slurry obtained by kneading a hydrogen absorbing alloy powder 12a, a polyethylene oxide (PEO) powder as a binder 12b, and a suitable amount of water (a solvent for binder) to both surfaces of a metal core plate (active material holder) made of a punching metal, the core plate is dried. Then, after removing the active material layer 13 from the core plate 11 by a means such as cutting and the like, a definite amount of water (a solvent for binder) is sprayed to the cut surface (the exposed surface of the core plate 11) to attach the water to the cur surface followed by drying to provide a hydrogen absorbing alloy electrode 10, which is disposed at the outermost side of the electrode group.

Abstract: In a rectangular alkaline storage battery, the sides of negative cores of negative electrode plates 10, which are disposed at the outermost positions of the group of electrode plates and oppose an outer casing can 40, are exposed. The pore ratios (ratio of total area taken up by pores to area of electrode plate) of the exposed cores must be made lower than those of the other unexposed cores. The pore ratio of the exposed negative core is specified as falling within a range of 10% to 40%. As a result, the negative electrode plates 10 are improved in binding strength, thereby inhibiting exfoliation of an active material. Further, there can be obtained a large rectangular alkaline storage battery which has superior permeability for a gas which would arise in the battery, an improved capacity ratio, and greater volumetric energy density.

Abstract: An electrode for the alkaline storage battery includes a binding agent containing thermoplastic xylene-formaldehyde resin. Since the thermoplastic xylene-formaldehyde resin is non-aqueous, it is not dissolved into moisture in the air or the alkaline electrolyte within the battery. The electrode is prepared by immersing an active-material-applied or -filled electrode substrate in a solution in which the thermoplastic xylene-formaldehyde resin is dissolved; immersing it in an emulsion of the thermoplastic xylene-formaldehyde resin with an emulsifier; or applying or filling a slurry of the active material with an emulsion of the thermoplastic xylene-formaldehyde resin to or in the electrode substrate. The electrode retains the active material using a binding agent which has excellent adhesion to the active material and imparts high binding capacity of the active materials with one another.

Abstract: An active material slurry 12a obtained by a mixing a powder of the active material with a binder and a solvent for the binder is heated to a predetermined temperature inside a slurry reservoir 20, and the heated active material slurry 12a is coated and adhered to an electrically conductive core body 11. The resulting body is then fed inside a drying furnace 28 to dry the coated and adhered active material slurry 12a by heating, and is rolled to a predetermined thickness by passing it through a pair of rolling rolls 29, thereby obtaining an electrode for alkaline batteries comprising an active material layer 12 on the both sides of the electrically conductive core body 11.

Abstract: A method of producing a hydrogen storage alloy, for use in alkaline storage batteries, includes two steps. A first step involves preparing alloy particles having a CaCu5-type crystal structure and the compositional formula MmNixCoyMnzM1−z, wherein M represents at least one element selected from the group consisting of aluminum (Al) and copper (Cu), 3.0≦x≦5.2, 0≦y≦1.2, 0.1≦z≦0.9, and 4.4≦x+y+z≦5.4. A second step involves immersing the alloy particles in an acid treating solution containing a cobalt compound and a copper compound, each in the amount of 0.1 to 5.0% by weight based on the weight of the alloy particles, and an organic additive to remove oxide films from and to reductively deposit cobalt and copper on a surface of each alloy particle to form a surface region surrounding a bulk region and having a graded composition.

Abstract: A hydrogen storage alloy, for use in alkaline storage batteries, having a CaCu5-type crystal structure and represented by the compositional formula MmNixCoyMnzMl-z (wherein M represents at least one element selected from the group consisting of aluminum (Al) and copper (Cu); x is a nickel (Ni) stoichiometry and satisfies 3.0≦x≦5.2; y is a cobalt (Co) stoichiometry and satisfies 0≦y≦1.2; z is a manganese (Mn) stoichiometry and satisfies 0.1≦z≦0.9; and the sum of x, y and z satisfies 4.4≦x+y+z≦5.4). The hydrogen storage alloy includes a bulk region having a CaCu5-type crystal structure and a substantially uniform composition and a surface region surrounding said bulk region and having a graded composition. When the sum in percentage of numbers of cobalt (Co) atoms and copper (Cu) atoms present in the surface region is given by a and that in the bulk region by b, the relationship a/b≧1.3 is satisfied.

Abstract: The invention provides a nickel-hydrogen storage battery which shows no deterioration of high rate discharge performance even after prolonged storage.

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: 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.

Abstract: A hydrogen-absorbing alloy electrode is prepared by 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 a hydrogen gas does not substantially occur; cooling the atmosphere from a temperature where absorbing of the hydrogen gas does not substantially occur to a temperature where the equilibrium hydrogen pressure of the hyrogen-absorbing alloy is equal to the hydrogen pressure in the atmosphere of the hydrogen gas and thereafter vacuum-evacuating and removing the hydrogen gas so that the hydrogen-absorbing alloy particle is cooled to room temperature while the hydrogen gas is exhausted; and thereafter introducing argon, nitrogen or carbon dioxide gas into the atmosphere, thereby returning the atmosphere to normal atmospheric pressure; and immersing the hydrogen-absorbing alloy particle so prepared in a solution containing an oxidation inhibiting agent.

Abstract: An active material slurry 12a obtained by a mixing a powder of the active material with a binder and a solvent for the binder is heated to a predetermined temperature inside a slurry reservoir 20, and the heated active material slurry 12a is coated and adhered to an electrically conductive core body 11. The resulting body is then fed inside a drying furnace 28 to dry the coated and adhered active material slurry 12a by heating, and is rolled to a predetermined thickness by passing it through a pair of rolling rolls 29, thereby obtaining an electrode for alkaline batteries comprising an active material layer 12 on the both sides of the electrically conductive core body 11.

Abstract: In a rectangular alkaline storage battery, the sides of negative cores of negative electrode plates 10, which are disposed at the outermost positions of the group of electrode plates and oppose an outer casing can 40, are exposed. The pore ratios (ratio of total area taken up by pores to area of electrode plate) of the exposed cores must be made lower than those of the other unexposed cores. The pore ratio of the exposed negative core is specified as falling within a range of 10% to 40%. As a result, the negative electrode plates 10 are improved in binding strength, thereby inhibiting exfoliation of an active material. Further, there can be obtained a large rectangular alkaline storage battery which has superior permeability for a gas which would arise in the battery, an improved capacity ratio, and greater volumetric energy density.

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 storage alloy electrode containing, as a principal active material, a powder of hydrogen storage alloy having a CaCu5 crystal structure and represented by the formula MmNixCoyMnzMw where M is at least one element selected from aluminum (Al) and copper (Cu), x is between 3.0 and 5.2, y is between 0 and 1.2, z is between 0.1 and 0.9, w is between 0.1 and 0.9, and the sum of x, y, z and w is between 4.4 and 5.4. The hydrogen storage alloy powder particles have a surface region and a bulk region enclosed within the surface region and have a higher nickel content in the surface region than in the bulk region. The hydrogen storage alloy electrode further contains an oxide and/or hydroxide of at least one rare-earth element selected from ytterbium (Yb), samarium (Sm), erbium (Er) and gadolinium (Gd).

Abstract: In the present invention, a hydrogen absorbing alloy obtained by sintering hydrogen absorbing alloy powder containing not less than 50% by weight of particles having a particle diameter of not more than 25 &mgr;m at a temperature of not more than 850° C. is used for a hydrogen absorbing alloy electrode for an alkali storage battery, and the hydrogen absorbing alloy electrode for an alkali storage battery is used as a negative electrode of the alkali storage battery.

Abstract: After coating a hydrogen absorbing alloy slurry obtained by kneading a hydrogen absorbing alloy powder 12a, a polyethylene oxide (PEO) powder as a binder 12b, and a suitable amount of water (a solvent for binder) to both surfaces of a metal core plate (active material holder) made of a punching metal, the core plate is dried. Then, after removing the active material layer 13 from the core plate 11 by a means such as cutting and the like, a definite amount of water (a solvent for binder) is sprayed to the cut surface (the exposed surface of the core plate 11) to attach the water to the cur surface followed by drying to provide a hydrogen absorbing alloy electrode 10, which is disposed at the outermost side of the electrode group.

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 Å 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≧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 Å 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≧1.20 is used for a hydrogen absorbing alloy electrode in an alkali secondary battery.

Abstract: A hydrogen absorbing alloy electrode is provided which has an excellent oxygen gas absorbing capacity and further improved in charge-discharge cycle characteristics and high-rate discharge characteristics. The electrode contains a powder prepared by mixing a hydrogen absorbing alloy powder with a powder of at least one complex oxide selected from the group consisting of a ZrO2—Y2O3 solid solution, ZrO2—CaO solid solution, CeO2—Gd2O3 solid solution, CeO2—La2O3 solid solution, ThO2—Y2O3 solid solution, Bi2O3—Y2O3 solid solution, Bi2O3—Gd2O3 solid solution, Bi2O3—Nb2O3 solid solution and Bi2O3—WO3 solid solution. Preferably the electrode contains 0.1 to 10 wt. % of the complex oxide powder based on the combined amount of the two powders.