Sanyo Electric Co., Ltd.

Teruhiko Imoto

Mamoru Kimoto

Nobuyuki Higashiyama

Koji Nishio

Shin Fujitani

Kikuko Kato

Yohei Hirota

Ikuo Yonezu

Masutaka Ouchi

Yoshinori Matsuura

Tadashi Ise

Tetsuyuki Murata

Yasuhiko Ikeda

Mitsuzo Nogami

Yasushi Kuroda

Masao Inoue

Hiroshi Nakamura

Koichi Nishimura

Masao Takee

Mitsuzou Nogami

Yasuhiko Itoh

Kenji Nasako

Atsutoshi Ako

Makoto Ochi

Motoo Tadokoro

Naoki Hiro

Toshikazu Yoshida

Takahiro Yonesaki

Yumiko Nakamura

Takuya Hashimoto

Hiroshi Fukuda

Kousuke Satoguchi

Kouichi Satou

Takashi Yamaguchi

Yoshihiro Masuda

Koji Miki

Takayuki Murakami

Koji Akashi

Yasumasa Kondou

Kiyoshi Morita

Yasumasa Kondo

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 CaCu-type crystal structure and the compositional formula MmNiCoMnM, wherein M represents at least one element selected from the group consisting of aluminum (Al) and copper (Cu), 3.0&#x2266;x&#x2266;5.2, 0&#x2266;y&#x2266;1.2, 0.1&#x2266;z&#x2266;0.9, and 4.4&#x2266;x+y+z&#x2266;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&#x2267;1.3 is satisfied.

Method for production of hydrogen storage alloy for use in alkaline storage batteries

After coating a hydrogen absorbing alloy slurry obtained by kneading a hydrogen absorbing alloy powder , a polyethylene oxide (PEO) powder as a binder , 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 from the core plate 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 ) to attach the water to the cur surface followed by drying to provide a hydrogen absorbing alloy electrode , which is disposed at the outermost side of the electrode group.

Hydrogen absorbing alloy electrode, manufacturing method thereof, and alkaline storage battery equipped with the hydrogen absorbing alloy electrode

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.

Electrode for alkaline storage battery and method of manufacturing the same

In a rectangular alkaline storage battery, the sides of negative cores of negative electrode plates , which are disposed at the outermost positions of the group of electrode plates and oppose an outer casing can , 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 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.

Rectangular alkaline storage battery

An active material slurry 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 and the heated active material slurry is coated and adhered to an electrically conductive core body The resulting body is then fed inside a drying furnace to dry the coated and adhered active material slurry by heating, and is rolled to a predetermined thickness by passing it through a pair of rolling rolls thereby obtaining an electrode for alkaline batteries comprising an active material layer on the both sides of the electrically conductive core body On drying the active material slurry that is coated and adhered to the electrically conductive core body the transfer of the binder inside the active material slurry is suppressed, such that the decrease in the amount of the binder inside the active material layer in the vicinity of the electrically conductive core body is prevented from occurring. Thus is obtained an electrode for alkaline batteries improved in adhesion strength.

Method for producing electrode for alkali batteries

A hydrogen storage alloy, for use in alkaline storage batteries, having a CaCu -type crystal structure and represented by the compositional formula MmNi Co Mn M (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&lE;x&lE;5.2; y is a cobalt (Co) stoichiometry and satisfies 0&lE;y&lE;1.2; z is a manganese (Mn) stoichiometry and satisfies 0.1&lE;z&lE;0.9; and the sum of x, y and z satisfies 4.4&lE;x&plus;y&plus;z&lE;5.4). The hydrogen storage alloy includes a bulk region having a CaCu -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&gE;1.3 is satisfied.

Hydrogen storage alloy for use in alkaline storage batteries and method for production thereof

The invention provides a hydrogen absorbing alloy electrode obtained by the step P of preparing a hydrogen absorbing alloy powder containing cobalt and nickel, the step P 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 P 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 P 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.

Hydrogen absorbing alloy powder and process for producing same

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&deg; C.&tilde;40&deg; 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.

Method of manufacturing hydrogen-absorbing alloy electrode

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.

A hydrogen storage alloy electrode containing, as a principal active material, a powder of hydrogen storage alloy having a CaCu crystal structure and represented by the formula MmNi Co Mn M 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).

Hydrogen storage alloy electrode and method for manufacture thereof

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&deg; 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.

Hydrogen absorbing alloy for alkali storage battery, hydrogen absorbing alloy electrode for alkali storage battery, and alkali storage battery

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 &angst; 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&gE;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 &angst; 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&gE;1.20 is used for a hydrogen absorbing alloy electrode in an alkali secondary battery.

Hydrogen absorbing alloy electrode, method of fabricating hydrogen absorbing alloy electrode, and alkali secondary battery

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 ZrO &mdash;Y O solid solution, ZrO &mdash;CaO solid solution, CeO &mdash;Gd O solid solution, CeO &mdash;La O solid solution, ThO &mdash;Y O solid solution, Bi O &mdash;Y O solid solution, Bi O &mdash;Gd O solid solution, Bi O &mdash;Nb O solid solution and Bi O &mdash;WO 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.

Hydrogen absorbing alloy electrode and process for producing same

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&lE;a&lE;5.2, 0&lE;b&lE;1.2, 0.1&lE;c&lE;0.9, 0.1&lE;d&lE;0.8, wherein X is the sum of the atomic ratios a, b, c, and d, such that, X&equals;a&plus;b&plus;c&plus;d and, is in the range of 4.4&lE;X&lE;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.

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Itano-gun, Japan

Teruhiko Imoto