Sanyo Electric Co., Ltd.

Nobuyuki Higashiyama

Mamoru Kimoto

Koji Nishio

Teruhiko Imoto

Kikuko Kato

Shin Fujitani

Yoshinori Matsuura

Ikuo Yonezu

Yohei Hirota

Masutaka Ouchi

Yasuhiko Itoh

Mitsuzo Nogami

Yasushi Kuroda

Takeshi Ogasawara

Mitsuzou Nogami

Mutsumi Yano

Toshihiko Saito

Mitsunori Tokuda

Yoshifumi Magari

Tadashi Ise

Takahiro Isono

Hiroshi Fukuda

Takuya Hashimoto

Yoshihiro Masuda

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

A non-sintered nickel electrode for an alkaline storage battery, characterized in that nickel hydroxide particles as active material particles thereof contain a cobalt having a valence of 3 to 3.2 as a solid solution element. The nickel electrode has excellent charging capability.

Non-sintered nickel electrode for alkaline storage battery

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

A positive active material for sealed alkaline storage batteries is obtainable by subjecting &bgr;-nickel hydroxide, together with at least one additive selected from yttrium, gadolinium, erbium and ytterbium, and oxides, hydroxides, fluorides and chlorides thereof, to an oxidation treatment with an oxidizing agent in an aqueous alkaline solution. The positive active material contains nickel with a valence number in a range from 2.1 to 3.4.

Positive active material for use in sealed alkaline storage batteries

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

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.

Positive electrode active material for alkaline storage batteries, positive electrode for alkaline storage batteries, and alkaline storage battery

The sealed alkaline storage battery of this invention includes a nonsintered nickel positive electrode using, as an active material, manganese-containing &agr;-nickel hydroxide including, as a solid-solution element, 15 through 50 wt % of manganese on the basis of a total amount of nickel and manganese; a negative electrode; and an alkaline electrolyte including 0.55 through 0.80 g of water per gram of the manganese-containing &agr;-nickel hydroxide. In this manner, the invention provides an alkaline storage battery exhibiting high positive electrode active material utilization for a large number of charge-discharge cycles.

Sealed alkaline storage battery with a manganese containing NiOH electrode

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.

In a pasted hydrogen-absorbing alloy electrode of this invention, an active material layer made from a mixture of a hydrogen-absorbing alloy powder, a composite particle powder including carbon particles and a rare earth compound for partially coating surfaces of the carbon particles, and a binder is formed on a current collector. When this pasted hydrogen-absorbing alloy electrode is used in an alkaline storage battery, the alkaline storage battery can attain small increase of the internal pressure during charge, large discharge capacity in high rate discharge and good charge-discharge cycle performance.

Pasted hydrogen-absorbing alloy electrode for alkaline storage battery

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,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,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.

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Ikeda, Japan

Nobuyuki Higashiyama