JP3432971B2 - Hydrogen storage alloy electrodes for metal-hydride alkaline storage batteries - Google Patents

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【発明の属する技術分野】本発明は、金属−水素化物ア
ルカリ蓄電池用の水素吸蔵合金電極に係わり、詳しく
は、充放電サイクル初期の高率放電特性、充放電サイク
ル特性及び電池内圧特性のいずれにも優れる金属−水素
化物アルカリ蓄電池を得ることを可能にする水素吸蔵合
金電極を提供することを目的とした、水素吸蔵材たる水
素吸蔵合金の改良に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen storage alloy electrode for a metal-hydride alkaline storage battery, and more specifically to any of high rate discharge characteristics, charge / discharge cycle characteristics and battery internal pressure characteristics at the beginning of charge / discharge cycles. The present invention also relates to improvement of a hydrogen storage alloy, which is a hydrogen storage material, for the purpose of providing a hydrogen storage alloy electrode capable of obtaining an excellent metal-hydride alkaline storage battery.

【０００２】[0002]

【従来の技術及び発明が解決しようとする課題】近年、
正極に水酸化ニッケルなどの金属化合物を使用し、負極
に新素材の水素吸蔵合金を使用した金属・水素化物アル
カリ蓄電池が、単位重量及び単位体積当たりのエネルギ
ー密度が高く、高容量化が可能であることから、ニッケ
ル・カドミウム蓄電池に代わる次世代のアルカリ蓄電池
として注目されている。2. Description of the Related Art In recent years,
A metal / hydride alkaline storage battery that uses a metal compound such as nickel hydroxide for the positive electrode and a new material hydrogen storage alloy for the negative electrode has a high energy density per unit weight and unit volume and is capable of high capacity. Therefore, it is attracting attention as a next-generation alkaline storage battery that replaces the nickel-cadmium storage battery.

【０００３】金属・水素化物アルカリ蓄電池用の水素吸
蔵合金としては、通常、鋳型内の合金溶湯を水冷凝固さ
せた後、粉砕して得たものが使用されている（以下、こ
の水素吸蔵合金を「通常凝固品」と称する。）。As a hydrogen storage alloy for a metal / hydride alkaline storage battery, one obtained by pulverizing a molten alloy in a mold after water-cooling solidification is generally used (hereinafter, this hydrogen storage alloy will be referred to as "hydrogen storage alloy"). Referred to as "normally coagulated product").

【０００４】しかしながら、通常凝固品には偏析（成分
元素濃度の偏り）が多く存在するために、充放電時に水
素を吸蔵又は放出する際に合金粒子に割れが生じて、比
表面積が増加し易い。このため、通常凝固品を負極材料
として使用した金属・水素化物アルカリ蓄電池は、充放
電サイクル初期の高率放電特性には優れる反面、偏析部
分が酸化劣化（腐食）の起点になり易いことからサイク
ル寿命が一般に短いという問題を有していた。However, since a solidified product usually has a large amount of segregation (deviation of concentration of component elements), alloy particles are cracked when hydrogen is occluded or released during charging / discharging, and the specific surface area is apt to increase. . Therefore, a metal / hydride alkaline storage battery that uses a solidified product as a negative electrode material is excellent in high rate discharge characteristics at the beginning of the charge / discharge cycle, but the segregated portion easily becomes a starting point of oxidative deterioration (corrosion). It has a problem that the life is generally short.

【０００５】サイクル寿命を改善する方法として、通常
凝固品にアニール処理（所定温度に所定時間加熱保持す
る処理）を施したものを使用することが、先に提案され
ている（特開昭６０−８９０６６号）。As a method for improving the cycle life, it has been previously proposed to use a solidified product that has been subjected to an annealing treatment (a treatment of heating and holding at a predetermined temperature for a predetermined time) (Japanese Patent Laid-Open No. 60-60). 89066).

【０００６】しかしながら、通常凝固品にアニール処理
を施すと、偏析が少なくなるため、未処理のものに比べ
てサイクル寿命は長くなる反面、このように偏析が少な
くなる上に、結晶粒の大きさ（希土類元素の濃度が高い
層と同濃度が低い層とが交互に出現する層状構造に於け
る隣接する二層の厚みの和）が大きくなり過ぎるため
に、粒子に割れが生じにくくなり、充放電サイクル初期
の高率放電特性が未処理のものに比べて著しく低下す
る。However, when the solidified product is usually annealed, segregation is reduced, so that the cycle life is longer than that of the untreated product. On the other hand, the segregation is reduced and the size of the crystal grains is increased. Since (the sum of the thicknesses of two adjacent layers in a layered structure in which a layer having a high concentration of rare earth elements and a layer having a low concentration of rare earth elements alternately appear) becomes too large, cracks are less likely to occur in the particles, and The high rate discharge characteristics in the initial stage of the discharge cycle are remarkably deteriorated as compared with the untreated one.

【０００７】通常凝固品に上述した解決困難な問題があ
ることに鑑み、最近、高速回転するロールの周面に合金
溶湯を噴出させて急冷凝固させる所謂単ロール法により
作製した水素吸蔵合金が金属・水素化物アルカリ蓄電池
用の負極材料として提案されている（特開平６−１８７
９７９号公報等参照）。In view of the above-described difficult problems to solve in a normally solidified product, recently, a hydrogen storage alloy produced by a so-called single roll method in which a molten alloy is jetted to the peripheral surface of a roll rotating at high speed to rapidly solidify is a metal. Proposed as a negative electrode material for hydride alkaline storage batteries (Japanese Patent Laid-Open No. 6-187)
979, etc.).

【０００８】この単ロール法により作製した水素吸蔵合
金は、合金溶湯を急冷凝固させて得たものであるので、
合金溶湯が凝固する際に重力場の影響を受けにくく、通
常凝固品に比べて、偏析が少ない。Since the hydrogen storage alloy produced by this single roll method is obtained by quenching and solidifying the molten alloy,
When the molten alloy is solidified, it is less affected by the gravitational field, and segregation is less than that of a normally solidified product.

【０００９】しかしながら、単ロール法により作製した
水素吸蔵合金は、結晶粒の大きさが不均一である。この
ため、充放電サイクルが進むにつれて、割れ易い部分
（結晶粒の大きさが大きい開放面側）と、割れにくい部
分（結晶粒の大きさが小さいロール面側）とが存在す
る。However, the hydrogen storage alloy produced by the single roll method has nonuniform crystal grain sizes. Therefore, as the charging / discharging cycle progresses, there are portions that are easily cracked (on the open surface side where the crystal grain size is large) and portions that are difficult to crack (on the roll surface side where the crystal grain size is small).

【００１０】また、特開昭６３−２９１３６３号公報に
は、結晶粒が一定の結晶面（（ｈｋ０）面と思われ
る。）に配向した厚さ４０μｍ以下の薄片状の水素吸蔵
合金を粉砕したものを電極材料として使用することが好
ましいことが示されている。しかし、この水素吸蔵合金
では合金粒子の表面に選択配向面が現れるため、電極触
媒能が悪く、充放電サイクル初期の高率放電特性が良く
ないという問題がある。加えて、厚さ４０μｍ以下の薄
片を使用した場合には、粉砕後の合金粒子が細かいの
で、合金粒子間の接触抵抗が大きい。このため、水素吸
蔵合金の利用率が低く、サイクル寿命が短いという問題
もある。Further, in JP-A-63-291363, a flaky hydrogen storage alloy having a thickness of 40 μm or less in which crystal grains are oriented in a constant crystal plane (probably (hk0) plane) is pulverized. It has been shown that it is preferable to use one as an electrode material. However, in this hydrogen storage alloy, the selective orientation plane appears on the surface of the alloy particles, so that there is a problem that the electrode catalyst ability is poor and the high rate discharge characteristics at the beginning of the charge and discharge cycle are not good. In addition, when a thin piece having a thickness of 40 μm or less is used, since the alloy particles after pulverization are fine, the contact resistance between the alloy particles is large. Therefore, there is a problem that the utilization rate of the hydrogen storage alloy is low and the cycle life is short.

【００１１】図２は、単ロール法により作製した水素吸
蔵合金Ｂを、帯長方向に沿って帯面に垂直な面でカット
したときの断面に現れる結晶粒の様子を模式的に示す拡
大断面図である（一部のみ描写）。図中、白色部２１は
希土類元素の濃度が高い層であり、黒色部２２は同濃度
が低い層であり、隣接するこれら二層の厚みの和が結晶
粒の大きさを示す。２５は、薄帯の厚みである。図２に
示すように、開放面側Ｏの結晶粒の大きさ２３は大き
く、ロール面側Ｒの結晶粒の大きさ２４は小さい。結晶
粒の大きさ２３が大きい開放面側Ｏは割れ易くて活性化
し易いが、結晶粒の大きさ２４が小さいロール面側Ｒは
割れにくくて活性化しにくい。その結果、活性化し易い
開放面側Ｏの充放電深度が深くなるため、この水素吸蔵
合金Ｂは、充放電を繰り返すと微粉化し易い。FIG. 2 is an enlarged cross-sectional view schematically showing the appearance of crystal grains appearing in the cross section of the hydrogen storage alloy B produced by the single roll method when cut along the strip length direction along a plane perpendicular to the strip surface. It is a figure (only a part is drawn). In the figure, the white portion 21 is a layer having a high concentration of rare earth elements, and the black portion 22 is a layer having a low concentration thereof, and the sum of the thicknesses of these two adjacent layers indicates the size of the crystal grain. 25 is the thickness of the ribbon. As shown in FIG. 2, the crystal grain size 23 on the open surface side O is large and the crystal grain size 24 on the roll surface side R is small. The open surface side O having a large crystal grain size 23 is easily cracked and activated, while the roll surface side R having a small crystal grain size 24 is hard to crack and activated. As a result, the charge / discharge depth on the open surface side O, which is easily activated, becomes deep, and therefore the hydrogen storage alloy B is easily pulverized when charge / discharge is repeated.

【００１２】このように、単ロール法により作製した水
素吸蔵合金を使用した金属−水素化物アルカリ蓄電池に
は、充放電を繰り返すと水素吸蔵合金が微粉化し易いた
めにサイクル寿命が短いという欠点があり、その改善が
嘱望されていた。As described above, the metal-hydride alkaline storage battery using the hydrogen storage alloy produced by the single roll method has a drawback that the hydrogen storage alloy is easily pulverized when the charge and discharge are repeated, so that the cycle life is short. , The improvement was hoped for.

【００１３】本発明は、以上の事情に鑑みなされたもの
であって、その目的とするところは、充放電サイクル初
期の高率放電特性、充放電サイクル特性及び電池内圧特
性のいずれにも優れる金属−水素化物アルカリ蓄電池を
得ることを可能にする水素吸蔵合金電極を提供するにあ
る。The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a metal having excellent high rate discharge characteristics at the beginning of a charge / discharge cycle, charge / discharge cycle characteristics, and battery internal pressure characteristics. -To provide a hydrogen storage alloy electrode making it possible to obtain a hydride alkaline storage battery.

【００１４】[0014]

【課題を解決するための手段】上記目的を達成するため
の本発明に係る金属−水素化物アルカリ蓄電池用の水素
吸蔵合金電極（本発明電極）は、ロール面側の下記に定
義する結晶粒の大きさの最小が０．２μｍ以上、開放面
側の下記に定義する結晶粒の大きさの最大が２０μｍ以
下である、単ロール法により作製された平均厚み０．０
８〜０．３５ｍｍ（但し、０．０８ｍｍ以上、０．２３
ｍｍ未満の範囲を除く）の一般式：ＭｍＲ _x （Ｍｍはミ
ッシュメタル；ＲはＮｉ、Ｃｏ、Ａｌ及びＭｎからな
る；ｘは４．４〜５．２）で表される薄帯状の希土類・
ニッケル系水素吸蔵合金を、粉砕して得た平均粒径２５
〜７０μｍの合金粉末が、水素吸蔵材として使用された
ものである。A hydrogen storage alloy electrode (invention electrode) for a metal-hydride alkaline storage battery according to the present invention for achieving the above object has a crystal grain defined on the roll surface side as defined below. An average thickness of 0.0 produced by a single roll method, in which the minimum size is 0.2 μm or more and the maximum size of crystal grains defined below on the open surface side is 20 μm or less.
8 to 0.35 mm (however, 0.08 mm or more, 0.23
( Excluding the range of less than mm) : MmR _x (Mm is
Ash metal; R consists of Ni, Co, Al and Mn
X is a ribbon-shaped rare earth represented by 4.4 to 5.2)
An average particle size of 25 obtained by crushing a nickel-based hydrogen storage alloy
The alloy powder having a particle size of 70 μm is used as the hydrogen storage material.

【００１５】結晶粒の大きさ：合金中の希土類元素の平
均濃度と比べて希土類元素の濃度が高い層と同濃度が低
い層とが交互に出現する多層構造に於けるこれら二層の
厚みの和をいう。Grain size: The level of rare earth elements in the alloy
It is the sum of the thicknesses of these two layers in a multi-layer structure in which a layer having a higher concentration of rare earth elements and a layer having a lower concentration of the same appear alternately as compared with the uniform concentration .

【００１６】上記平均粒径とは、下式（１）で定義され
る体積加重平均径ＭＶである。この体積加重平均径ＭＶ
は、粒径に分布のある粉体でも、或る現象に対する粒径
の効果が粒径ＭＶなる均一な粒子群と同じであれば、体
積加重平均径ＭＶを代表径として使用した方が便利であ
るとの考え方に基づいて導入したものである。 ＭＶ＝Σ（ＶｉＤｉ）／ΣＶｉ …（１） 但し、式中、Ｄｉ：各粒径区分に於ける代表径 Ｖｉ：各粒径区分に於ける体積割合The average particle diameter is the volume weighted average diameter MV defined by the following equation (1). This volume-weighted average diameter MV
For a powder having a particle size distribution, it is more convenient to use the volume-weighted average diameter MV as a representative diameter if the effect of the particle size on a certain phenomenon is the same as that of a uniform particle group of the particle size MV. It was introduced based on the idea that there is. MV = Σ (ViDi) / ΣVi (1) where, Di: representative diameter in each particle size section Vi: volume ratio in each particle size section

【００１７】本発明における合金粉末の平均粒径は２５
〜７０μｍに規制される。これは、平均粒径が７０μｍ
を越えて大きくなると、比表面積が小さくなり過ぎるた
めに、過充電時に酸素ガスを速やかに消費することがで
きなくなり、一方平均粒径が２５μｍ未満と小さくなる
と、合金粒子間の接触が悪くなり、合金粒子の一部しか
反応に関与しなくなるため、反応熱が高くなって水素が
解離し易くなり、その結果電池内圧が上昇するからであ
る。The average particle size of the alloy powder in the present invention is 25.
It is regulated to ˜70 μm. This has an average particle size of 70 μm
When the average particle size is less than 25 μm, the contact between the alloy particles deteriorates because the specific surface area becomes too small and oxygen gas cannot be rapidly consumed during overcharge. This is because only a part of the alloy particles participates in the reaction, the reaction heat becomes high, hydrogen is easily dissociated, and as a result, the internal pressure of the battery rises.

【００１８】本発明における希土類・ニッケル系水素吸
蔵合金の薄帯の厚み（平均厚み）は０．０８〜０．３５
ｍｍ（但し、０．０８ｍｍ以上、０．２３ｍｍ未満の範
囲を除く）に規制される。これは、薄帯の厚みが０．３
５ｍｍを越えると、薄帯の厚さ方向の結晶粒の大きさが
不均一なため、サイクル寿命の短命化を招き、一方薄帯
の厚みが０．０８ｍｍ未満であると、合金の粒子表面が
（ｈｋ０）面に配向し、その結果電極触媒能が低下する
ため、充放電サイクル初期の高率放電特性の低下を招く
とともに、サイクル寿命の短命化を招くからである。サ
イクル寿命の短命化を招くのは、電極を構成する合金粒
子の粒径が小さいために、電極内の合金粒子間の接触抵
抗が増大し、水素吸蔵合金粉末の利用効率が低下するか
らである。The thickness (average thickness) of the ribbon of the rare earth / nickel hydrogen storage alloy in the present invention is 0.08 to 0.35.
mm (However, the range of 0.08 mm or more and less than 0.23 mm
Are excluded) . This has a ribbon thickness of 0.3.
If the thickness exceeds 5 mm, the crystal grain size in the thickness direction of the ribbon becomes non-uniform, which leads to a shortened cycle life. On the other hand, if the thickness of the ribbon is less than 0.08 mm, the grain surface of the alloy is This is because the (hk0) plane is oriented and, as a result, the electrode catalytic activity is reduced, which leads to a reduction in high-rate discharge characteristics at the beginning of a charge / discharge cycle and a reduction in cycle life. The reason why the cycle life is shortened is that the contact resistance between the alloy particles in the electrode is increased and the utilization efficiency of the hydrogen storage alloy powder is reduced because the particle diameter of the alloy particles forming the electrode is small. .

【００１９】また、本発明における希土類・ニッケル系
水素吸蔵合金はロール面側の結晶粒の大きさの最小が
０．２μｍ以上、開放面側の結晶粒の大きさの最大が２
０μｍ以下のものに規制される。これは、結晶粒の大き
さの最小及び最大が上記範囲を外れると、充放電サイク
ル初期の高率放電特性が低下したり、サイクル寿命が短
命化したりするからである。すなわち、０．２μｍ未満
の結晶粒がロール面側に混在すると、水素吸蔵合金が割
れにくくなるために、充放電サイクル初期の高率放電特
性の低下を招く。一方、２０μｍを越える結晶粒が開放
面側に混在すると、水素吸蔵合金が微粉化して酸化劣化
し易くなるために、サイクル寿命の短命化を招く。In the rare earth / nickel-based hydrogen storage alloy according to the present invention, the minimum crystal grain size on the roll surface side is 0.2 μm or more, and the maximum crystal grain size on the open surface side is 2 μm.
It is regulated to 0 μm or less. This is because if the minimum and maximum crystal grain sizes deviate from the above range, the high rate discharge characteristics at the beginning of the charge / discharge cycle will deteriorate, and the cycle life will shorten. That is, if crystal grains of less than 0.2 μm are mixed on the roll surface side, the hydrogen storage alloy is less likely to crack, which leads to deterioration of the high rate discharge characteristics in the initial charge / discharge cycle. On the other hand, when crystal grains having a size of more than 20 μm are mixed on the open surface side, the hydrogen storage alloy is pulverized and is easily oxidized and deteriorated, which shortens the cycle life.

【００２０】[0020]

【発明の実施の形態】上記合金粉末としては、電池内圧
特性に優れた金属−水素化物アルカリ蓄電池を与える水
素吸蔵合金電極を得る上で、薄帯状の希土類・ニッケル
系水素吸蔵合金を、粉砕し、さらに酸液に浸漬すること
により表面処理した表面処理後の平均粒径２５〜６０μ
ｍの粉末が好適である。BEST MODE FOR CARRYING OUT THE INVENTION As the alloy powder, a ribbon-shaped rare earth / nickel-based hydrogen storage alloy is pulverized in order to obtain a hydrogen storage alloy electrode which gives a metal-hydride alkaline storage battery having excellent battery internal pressure characteristics. , Further surface-treated by dipping in an acid solution, average particle size after surface treatment 25-60μ
m powder is preferred.

【００２１】本発明で使用する希土類・ニッケル系水素
吸蔵合金は、一般式：ＭｍＲ _x （Ｍｍはミッシュメタ
ル；ＲはＮｉ、Ｃｏ、Ａｌ及びＭｎからなる；ｘは４．
４〜５．２）で表されるＭｍ・Ｎｉ・Ｃｏ・Ａｌ・Ｍｎ
合金である。 Rare earth / nickel based hydrogen used in the present invention
The storage alloy has the general formula: MmR _x (Mm is mischmeta)
R is composed of Ni, Co, Al and Mn; x is 4.
Mm, Ni, Co, Al, and Mn represented by 4 to 5.2)
It is an alloy.

【００２２】上記Ｍｍ・Ｎｉ・Ｃｏ・Ａｌ・Ｍｎ合金の
好適なＣｏ含有量は、Ｍｍ１モル部に対してＣｏ０．４
〜０．９モル部であり、また好適なＮｉ含有量は、Ｍｍ
１モル部に対してＮｉ２．８〜３．６モル部である。The preferable Co content of the Mm.Ni.Co.Al.Mn alloy is 0.4 Co per 1 mol part of Mm.
.About.0.9 parts by mole, and a suitable Ni content is Mm.
The amount of Ni is 2.8 to 3.6 parts by mole with respect to 1 part by mole.

【００２３】本発明電極は、例えば合金溶湯を単ロール
法により５０〜１０００ｃｍ／秒のロール周速度で不活
性ガス又は真空中にて急冷凝固して薄帯状の希土類・ニ
ッケル系水素吸蔵合金を作製し、該薄帯状の希土類・ニ
ッケル系水素吸蔵合金を不活性ガス又は真空中にて６２
０〜１０００°Ｃの温度でアニール処理し、該アニール
処理した薄帯状の希土類・ニッケル系水素吸蔵合金を粉
砕して平均粒径２５〜７０μｍの合金粉末を作製し、該
合金粉末と結着剤溶液とを混合して得たスラリーを基材
（芯体）に塗布又は充填することにより作製される。芯
体の具体例としては、発泡状金属多孔体、金属繊維、炭
素繊維、金属メッシュ、パンチングメタルが挙げられ
る。合金溶湯を単ロール法により５０〜１０００ｃｍ／
秒のロール周速度で急冷凝固することにより、薄帯の平
均厚みを０．０８〜０．３５ｍｍ（但し、０．０８ｍｍ
以上、０．２３ｍｍ未満の範囲を除く）にすることがで
き、また急冷凝固後に６２０〜１０００°Ｃの温度でア
ニール処理することにより、結晶粒の大きさの最小を
０．２μｍ以上、最大を２０μｍ以下にすることができ
る。アニール処理した薄帯状の希土類・ニッケル系水素
吸蔵合金を粉砕後、さらに酸液に浸漬して表面処理する
場合には、先に述べたように、処理後の合金粉末の平均
粒径が２５〜６０μｍとなるようにすることが、電池内
圧特性に特に優れた金属−水素化物アルカリ蓄電池を与
える水素吸蔵合金電極を得る上で、好ましい。表面処理
する際の酸液としては、塩酸、硫酸、硝酸が例示され
る。In the electrode of the present invention, for example, a ribbon-shaped rare earth / nickel-based hydrogen storage alloy is prepared by rapidly solidifying molten alloy by a single roll method at a roll peripheral velocity of 50 to 1000 cm / sec in an inert gas or vacuum. Then, the ribbon-shaped rare earth / nickel-based hydrogen storage alloy is placed in an inert gas or in vacuum 62
Annealing is performed at a temperature of 0 to 1000 ° C., and the annealed ribbon-shaped rare earth / nickel-based hydrogen storage alloy is crushed to produce an alloy powder having an average particle diameter of 25 to 70 μm. It is prepared by coating or filling a base material (core body) with a slurry obtained by mixing with a solution. Specific examples of the core include a foamed metal porous body, metal fiber, carbon fiber, metal mesh, and punching metal. 50-1000 cm / of molten alloy by single roll method
By rapidly solidifying at a roll peripheral speed of 2 seconds, the average thickness of the thin strip is 0.08 to 0.35 mm (however, 0.08 mm
As described above, the range of less than 0.23 mm is excluded), and by performing annealing treatment at a temperature of 620 to 1000 ° C. after rapid solidification, the minimum grain size is 0.2 μm or more and the maximum is maximum. It can be 20 μm or less. When the annealed ribbon-shaped rare earth / nickel-based hydrogen storage alloy is crushed and then further immersed in an acid solution for surface treatment, as described above, the average particle diameter of the treated alloy powder is 25 to It is preferable that the thickness be 60 μm in order to obtain a hydrogen storage alloy electrode that provides a metal-hydride alkaline storage battery having particularly excellent battery internal pressure characteristics. Examples of the acid solution for the surface treatment include hydrochloric acid, sulfuric acid and nitric acid.

【００２４】上記薄帯の厚みは、ロール周速度に依存す
る。ロール周速度を速くして凝固速度を速くすると、薄
帯の平均厚みが小さくなる。一方、結晶粒の大きさは、
アニール処理時の温度（アニール温度）に依存する。通
常、アニール温度を高くすると結晶粒の大きさの最小は
大きくなるが、最大は殆ど変化しない。すなわちアニー
ル温度を高くすると結晶粒の大きさのバラツキが減少す
る。なお、アニール温度が１０００°Ｃを越えて合金の
融点（１２００°Ｃ程度）に近づくと、水素吸蔵合金が
結晶粒界で一部再溶解し、極めて割れにくくなって不活
性化する。アニール時間は１〜１０時間程度である。通
常、１０時間程度でアニール処理の効果が飽和する。The thickness of the ribbon depends on the peripheral speed of the roll. When the roll peripheral speed is increased and the solidification speed is increased, the average thickness of the ribbon becomes smaller. On the other hand, the crystal grain size is
It depends on the temperature (annealing temperature) during the annealing process. Usually, when the annealing temperature is raised, the minimum of the crystal grain size increases, but the maximum hardly changes. That is, when the annealing temperature is increased, the variation in crystal grain size is reduced. When the annealing temperature exceeds 1000 ° C. and approaches the melting point of the alloy (about 1200 ° C.), the hydrogen storage alloy partially remelts at the crystal grain boundaries, becomes extremely hard to crack, and becomes inactive. The annealing time is about 1 to 10 hours. Usually, the effect of annealing is saturated in about 10 hours.

【００２５】[0025]

【作用】本発明における希土類・ニッケル系水素吸蔵合
金は、薄帯の厚みが０．０８〜０．３５ｍｍ（但し、
０．０８ｍｍ以上、０．２３ｍｍ未満の範囲を除く）と
薄いので、薄帯の厚み方向の結晶粒の大きさが均一であ
る。このため、充放電サイクルにおいて、微粉化しにく
い。また、薄帯の厚みの下限を規制しているため合金の
粒子表面の（ｈｋ０）面への選択配向もさほど大きくな
く、電極触媒能が高い。The rare-earth / nickel-based hydrogen storage alloy according to the present invention has a ribbon thickness of 0.08 to 0.35 mm (however,
(Excluding a range of 0.08 mm or more and less than 0.23 mm) , the crystal grain size in the thickness direction of the ribbon is uniform. Therefore, it is less likely to be pulverized in the charge / discharge cycle. Moreover, since the lower limit of the thickness of the ribbon is regulated, the selective orientation of the grain surface of the alloy to the (hk0) plane is not so large, and the electrocatalytic ability is high.

【００２６】さらに、本発明における希土類・ニッケル
系水素吸蔵合金は、ロール面側に過小な結晶粒が存在せ
ず、且つ開放面側に過大な結晶粒が存在しないので、充
放電サイクル初期において、合金が適度に割れ、しかも
充放電を繰り返してもこなごなに微粉化することがな
い。Further, in the rare earth / nickel-based hydrogen storage alloy of the present invention, there are no excessively small crystal grains on the roll surface side and no excessively large crystal grains on the open surface side. The alloy cracks moderately and does not become finely pulverized even after repeated charging and discharging.

【００２７】さらにまた、合金粉末の平均粒径が２５〜
７０μｍに設定されているので、過充電時に正極で発生
した酸素ガスが速やかに水素吸蔵合金電極（負極）で消
費される。特に、酸液に浸漬して表面処理し、表面処理
後の平均粒径が２５〜６０μｍである水素吸蔵合金を使
用した場合には、合金表面の酸化膜が除去されているの
で、酸素ガスがより一層速やかに水素吸蔵合金電極で消
費される。Furthermore, the average particle size of the alloy powder is 25 to
Since the thickness is set to 70 μm, the oxygen gas generated at the positive electrode during overcharge is quickly consumed by the hydrogen storage alloy electrode (negative electrode). Particularly, when a hydrogen storage alloy having an average particle size after surface treatment of 25 to 60 μm is used by immersing in an acid solution for surface treatment, the oxide film on the alloy surface is removed, so The hydrogen storage alloy electrode is consumed more quickly.

【００２８】このため、本発明電極を負極に使用した金
属−水素化物アルカリ蓄電池は、充放電サイクル初期の
高率放電特性、充放電サイクル特性及び電池内圧特性の
いずれにも優れる。Therefore, the metal-hydride alkaline storage battery using the electrode of the present invention as the negative electrode is excellent in all of the high rate discharge characteristics at the beginning of the charge / discharge cycle, the charge / discharge cycle characteristics and the battery internal pressure characteristics.

【００２９】[0029]

【実施例】以下、本発明を実施例に基づいてさらに詳細
に説明するが、本発明は下記実施例に何ら限定されるも
のではなく、その要旨を変更しない範囲において適宜変
更して実施することが可能なものである。EXAMPLES The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to the following examples, and various modifications may be made without departing from the scope of the invention. Is possible.

【００３０】（実施例１〜９及び参考例１〜４） 〔水素吸蔵合金の作製〕 合金成分金属（いずれも純度９９．９％以上）を秤取し
て混合し、真空下で高周波溶解炉にて溶解した後、単ロ
ール法（ロール径：３５０ｍｍ）により表１に示す種々
の冷却速度（ロール周速度：５０、１００、３００、５
００又は１０００ｃｍ／秒）で冷却して、組成式：Ｍｍ
Ｎｉ_3.4 Ｃｏ_0.8 Ａｌ_0.3 Ｍｎ_0.5 で表される薄帯状の
希土類・ニッケル系水素吸蔵合金（帯長：約３０〜１０
０ｍｍ；帯幅：約２０〜５０ｍｍ）を作製した。これら
の薄帯の厚みを任意に１０箇所選んで測定し、その平均
値を薄帯の厚みとした。( Examples 1 to 9 and Reference Examples 1 to 4 ) [Preparation of Hydrogen Storage Alloy] Alloy component metals (each having a purity of 99.9% or more) are weighed and mixed, and the mixture is heated in a high-frequency melting furnace under vacuum. After being melted in, the various cooling rates shown in Table 1 (roll peripheral speed: 50, 100, 300, 5 by the single roll method (roll diameter: 350 mm))
00 or 1000 cm / sec), and the composition formula: Mm
A ribbon-shaped rare earth / nickel-based hydrogen storage alloy represented by Ni _3.4 Co _0.8 Al _0.3 Mn _0.5 (band length: about 30 to 10
0 mm; band width: about 20 to 50 mm) was produced. The thickness of these ribbons was arbitrarily selected and measured at 10 locations, and the average value was used as the thickness of the ribbons.

【００３１】次いで、これらの希土類・ニッケル系水素
吸蔵合金を表１に示す種々の温度（６２０、７００、８
００、９００、１０００又は１２００°Ｃ）で、Ａｒガ
ス中にて６時間アニール処理した。Next, these rare earth / nickel based hydrogen storage alloys were subjected to various temperatures (620, 700, 8) shown in Table 1.
Annealing treatment was performed in Ar gas at 00, 900, 1000 or 1200 ° C. for 6 hours.

【００３２】これらのアニール処理した各希土類・ニッ
ケル系水素吸蔵合金を、帯長方向に沿って帯面に垂直に
カットし、断面の反射電子線像を走査型電子顕微鏡（日
本電子線株式会社製、品番「ＪＥＯＬ８６６」）に観察
し、開放面側の結晶粒の大きさの最大及びロール面側の
結晶粒の大きさの最小を求めた。結晶粒の大きさの最大
及び最小は、反射電子線像で観察される隣接する白線部
の間隔を白線と垂直方向に測定して求めた（以下の結晶
粒の大きさの最大及び最小についても同様にして求め
た。）。結晶粒の大きさの最大及び最小は、いずれも各
希土類・ニッケル系水素吸蔵合金１０サンプルについて
の平均値である。Each of these annealed rare earth / nickel-based hydrogen storage alloys was cut perpendicularly to the strip surface along the strip length direction, and the backscattered electron image of the cross section was taken by a scanning electron microscope (manufactured by JEOL Ltd.). No. “JEOL866”), and the maximum crystal grain size on the open surface side and the minimum crystal grain size on the roll surface side were determined. The maximum and minimum crystal grain sizes were obtained by measuring the spacing between adjacent white line portions observed in a backscattered electron beam image in the direction perpendicular to the white line (also regarding the maximum and minimum crystal grain sizes below. Obtained in the same manner.). The maximum and minimum crystal grain sizes are average values for 10 samples of each rare earth / nickel-based hydrogen storage alloy.

【００３３】図１は、アニール処理した薄帯状の水素吸
蔵合金Ａの断面に現れた結晶粒の様子を示す模式図であ
る（一部のみ描写）。図中、白色部１は希土類元素及び
コバルト濃度が高く、マンガン濃度が低い層であり、黒
色部２は希土類元素及びコバルト濃度が低く、マンガン
濃度が高い層である。３は開放面側Ｏの結晶粒の大きさ
を示し、４はロール面側Ｒの結晶粒の大きさを示す。５
は薄帯の厚みを示す。図１に示すように、アニール処理
したためロール面側Ｒの結晶粒の大きさ４が大きくな
り、その結果開放面側Ｏの結晶粒の大きさ３との差が小
さくなって薄帯の厚さ方向の結晶粒の大きさが、アニー
ル処理前の水素吸蔵合金Ｂ（図２参照）に比べて、均一
化している。FIG. 1 is a schematic view showing a state of crystal grains appearing in a cross section of an annealing-processed ribbon-shaped hydrogen storage alloy A (only part of which is depicted). In the figure, a white portion 1 is a layer having a high rare earth element and cobalt concentration and a low manganese concentration, and a black portion 2 is a layer having a low rare earth element and cobalt concentration and a high manganese concentration. 3 indicates the size of crystal grains on the open surface side O, and 4 indicates the size of crystal grains on the roll surface side R. 5
Indicates the thickness of the ribbon. As shown in FIG. 1, the size of the crystal grains 4 on the roll surface side R becomes large due to the annealing treatment, and as a result, the difference from the size 3 of the crystal grains on the open surface side O becomes small and the thickness of the ribbon becomes small. The size of the crystal grains in the direction is more uniform than that of the hydrogen storage alloy B (see FIG. 2) before the annealing treatment.

【００３４】〔水素吸蔵合金電極の作製〕アニール処理
した各希土類・ニッケル系水素吸蔵合金を、不活性ガス
（Ａｒガス）雰囲気下において機械的に粉砕し、篩にか
けて、最大粒径が１００メッシュアンダー（以下の実施
例又は比較例においても、最大粒径は全て１００メッシ
ュアンダーに調節した）で、平均粒径（体積加重平均
径）が７０μｍの粉末を得た。平均粒径は２点法〔上式
（１）中のｉ＝２〕で求めた。なお、この平均粒径は、
レーザーを光源とし、フラウンホーファーの回折現象を
利用するレーザー回折法により粒度分布を測定して求め
た。測定装置としては、マイクロトラック粒度分析計
（Ｌｅｅｄｓ ＆ Ｎｏｒｔｈｒｕｐ社製、７９９１
型）を使用した。その後、上記粉末９０重量部と、ポリ
エチレンオキシドの２．５重量％水溶液１０重量部とを
混合して、スラリーを調製した。[Preparation of Hydrogen Storage Alloy Electrode] Each of the annealed rare earth / nickel based hydrogen storage alloys is mechanically crushed in an inert gas (Ar gas) atmosphere and sieved to give a maximum particle size of 100 mesh under. (Even in the following Examples or Comparative Examples, the maximum particle size was adjusted to 100 mesh under), and a powder having an average particle size (volume-weighted average size) of 70 μm was obtained. The average particle size was determined by the 2-point method [i = 2 in the above formula (1)]. The average particle size is
The particle size distribution was measured by a laser diffraction method using a laser as a light source and the Fraunhofer diffraction phenomenon. As a measuring device, Microtrack particle size analyzer (manufactured by Leeds & Northrup, 7991)
Type) was used. Then, 90 parts by weight of the above powder and 10 parts by weight of a 2.5% by weight aqueous solution of polyethylene oxide were mixed to prepare a slurry.

【００３５】次いで、このスラリーを鉄にニッケルめっ
きしてなるパンチングメタルに塗布し、乾燥して水素吸
蔵合金電極を作製した。Next, this slurry was applied to a punching metal obtained by nickel-plating iron and dried to produce a hydrogen storage alloy electrode.

【００３６】〔ニッケル・水素化物アルカリ蓄電池の作
製〕上記の各水素吸蔵合金電極を負極として、順にＡＡ
サイズ（単３型）の正極支配型のニッケル・水素化物ア
ルカリ蓄電池（電池容量：１２００ｍＡｈ±１０ｍＡ
ｈ）Ａ１〜Ａ１３を作製した。なお、正極としては従来
公知の焼結式ニッケル極を、セパレータとしてはポリア
ミド製の不織布を、アルカリ電解液としては３０重量％
水酸化カリウム水溶液を、それぞれ使用した。[Preparation of Nickel / Hydride Alkaline Storage Battery] AA was sequentially prepared by using each of the above hydrogen storage alloy electrodes as a negative electrode.
Size (AA type) positive electrode dominant nickel-hydride alkaline storage battery (battery capacity: 1200 mAh ± 10 mA
h) A1 to A13 were produced. A conventionally known sintered nickel electrode is used as the positive electrode, a polyamide non-woven fabric is used as the separator, and 30% by weight is used as the alkaline electrolyte.
Aqueous potassium hydroxide solution was used respectively.

【００３７】実施例１〜９及び参考例１〜４における合
金作製条件（ロール周速度及びアニール温度）、作製し
た合金粉末の平均粒径、薄帯の厚み、結晶粒の大きさの
最大及び最小を、表１にまとめて示す。Alloy production conditions (roll peripheral speed and annealing temperature) in Examples 1 to 9 and Reference Examples 1 to 4 , average grain size of the produced alloy powder, ribbon thickness, and maximum and minimum crystal grain sizes. Are summarized in Table 1.

【００３８】[0038]

【表１】 [Table 1]

【００３９】（比較例１） 単ロール法に代えて通常凝固法を使用したこと以外は実
施例１〜９と同様にして、同組成の塊状の希土類・ニッ
ケル系水素吸蔵合金を作製した。[0039] (Comparative Example 1) except for using a conventional coagulation method instead of the single roll method real
In the same manner as in Examples 1 to 9 , massive rare earth / nickel based hydrogen storage alloys having the same composition were produced.

【００４０】次いで、この合金を９００゜Ｃで６時間
（以下の実施例又は比較例においても、アニール時間は
全て６時間に統一した。）アニール処理した後、機械的
に粉砕し、篩にかけて、平均粒径が７０μｍ、結晶粒の
大きさの最大が３５μｍ、最小が１０μｍの粉末を作製
した。Next, this alloy was annealed at 900 ° C. for 6 hours (the annealing time was unified to 6 hours in all of the following Examples and Comparative Examples), mechanically crushed and sieved. A powder having an average particle size of 70 μm, a maximum crystal grain size of 35 μm, and a minimum grain size of 10 μm was produced.

【００４１】水素吸蔵材としてこの粉末を使用したこと
以外は実施例１〜９と同様にして、電池Ｂ１を作製し
た。A battery B1 was produced in the same manner as in Examples 1 to 9 except that this powder was used as the hydrogen storage material.

【００４２】（比較例２） ロール周速度を１０ｃｍ／秒とし、アニール温度を９０
０°Ｃとしたこと以外は実施例１〜９と同様にして、平
均粒径が７０μｍ、平均厚みが０．５７ｍｍ、開放面側
の結晶粒の大きさの最大が４０μｍ、ロール面側の結晶
粒の大きさの最小が０．２μｍの粉末を作製した。(Comparative Example 2) The roll peripheral velocity was set to 10 cm / sec, and the annealing temperature was set to 90.
In the same manner as in Examples 1 to 9 except that the temperature was 0 ° C., the average grain size was 70 μm, the average thickness was 0.57 mm, the maximum crystal grain size on the open face side was 40 μm, and the crystal on the roll face side was A powder having a minimum grain size of 0.2 μm was produced.

【００４３】水素吸蔵材としてこの粉末を使用したこと
以外は実施例１〜９と同様にして、電池Ｂ２を作製し
た。A battery B2 was produced in the same manner as in Examples 1 to 9 except that this powder was used as the hydrogen storage material.

【００４４】（比較例３） ロール周速度を３００ｃｍ／秒とし、アニール温度を５
００°Ｃとしたこと以外は実施例１〜９と同様にして、
平均粒径が７０μｍ、平均厚みが０．２３ｍｍ、開放面
側の結晶粒の大きさの最大が１５μｍ、ロール面側の結
晶粒の大きさの最小が０．０１μｍ以下の粉末を作製し
た。(Comparative Example 3) The roll peripheral velocity was 300 cm / sec, and the annealing temperature was 5
In the same manner as in Examples 1 to 9 except that the temperature was set to 00 ° C,
A powder having an average particle size of 70 μm, an average thickness of 0.23 mm, a maximum crystal grain size on the open surface side of 15 μm, and a minimum crystal grain size on the roll surface side of 0.01 μm or less was produced.

【００４５】水素吸蔵材としてこの粉末を使用したこと
以外は実施例１〜９と同様にして、電池Ｂ３を作製し
た。A battery B3 was produced in the same manner as in Examples 1 to 9 except that this powder was used as the hydrogen storage material.

【００４６】（比較例４） ロール周速度を３００ｃｍ／秒とし、アニール温度を１
２００°Ｃとしたこと以外は実施例１〜９と同様にし
て、平均粒径が７０μｍ、平均厚みが０．２３ｍｍ、開
放面側の結晶粒の大きさの最大が２５μｍ、ロール面側
の結晶粒の大きさの最小が０．４μｍの粉末を作製し
た。(Comparative Example 4) The roll peripheral velocity was 300 cm / sec, and the annealing temperature was 1.
In the same manner as in Examples 1 to 9 except that the temperature was 200 ° C., the average grain size was 70 μm, the average thickness was 0.23 mm, the maximum crystal grain size on the open face side was 25 μm, and the crystal on the roll face side was A powder having a minimum grain size of 0.4 μm was produced.

【００４７】水素吸蔵材としてこの粉末を使用したこと
以外は実施例１〜９と同様にして、電池Ｂ４を作製し
た。A battery B4 was produced in the same manner as in Examples 1 to 9 except that this powder was used as the hydrogen storage material.

【００４８】（比較例５） 単ロール法に代えて通常凝固法（水冷凝固法）を使用す
るとともに、アニール処理しなかったこと以外は実施例
１〜９と同様にして、平均粒径が７０μｍ、結晶粒の大
きさの最大が２５μｍ、最小が７μｍの粉末を作製し
た。(Comparative Example 5) An example except that a normal solidification method (water cooling solidification method) was used in place of the single roll method and no annealing treatment was carried out.
In the same manner as in 1 to 9 , powder having an average particle size of 70 μm, a maximum crystal grain size of 25 μm, and a minimum crystal grain size of 7 μm was produced.

【００４９】水素吸蔵材としてこの粉末を使用したこと
以外は実施例１〜９と同様にして、電池Ｂ５を作製し
た。A battery B5 was produced in the same manner as in Examples 1 to 9 except that this powder was used as the hydrogen storage material.

【００５０】（比較例６） ロール周速度を３００ｃｍ／秒とし、アニール処理しな
かったこと以外は実施例１〜９と同様にして、平均粒径
が７０μｍ、平均厚みが０．２３ｍｍ、開放面側の結晶
粒の大きさの最大が１０μｍ、ロール面側の結晶粒の大
きさの最小が０．０１μｍ以下の粉末を作製した。(Comparative Example 6) An average particle diameter of 70 μm, an average thickness of 0.23 mm, and an open surface were obtained in the same manner as in Examples 1 to 9 except that the roll peripheral speed was 300 cm / sec and no annealing treatment was performed. A powder having a maximum crystal grain size on the side of 10 μm and a minimum crystal grain size on the roll surface side of 0.01 μm or less was produced.

【００５１】水素吸蔵材としてこの粉末を使用したこと
以外は実施例１〜９と同様にして、電池Ｂ６を作製し
た。A battery B6 was produced in the same manner as in Examples 1 to 9 except that this powder was used as the hydrogen storage material.

【００５２】（比較例７）実施例１〜９ と同じ組成の合金溶湯（ＭｍＮｉ_3.4 Ｃｏ
_0.8 Ａｌ_0.3 Ｍｎ_0.5）をアトマイズ法により凝固させ
た後、９００°Ｃで６時間アニール処理して、水素吸蔵
合金粉末を作製した。平均粒径、結晶粒の大きさの最大
及び最小は、それぞれ７０μｍ、８μｍ、０．１μｍで
あった。[0052] (Comparative Example 7) molten alloy having the same composition as in Example 1 to 9 (MmNi _3.4 Co
_{After 0.8} Al _0.3 Mn _0.5 ) was solidified by the atomization method, it was annealed at 900 ° C. for 6 hours to prepare a hydrogen storage alloy powder. The maximum and minimum of the average grain size and the crystal grain size were 70 μm, 8 μm, and 0.1 μm, respectively.

【００５３】水素吸蔵材としてこの粉末を使用したこと
以外は実施例１〜９と同様にして、電池Ｂ７を作製し
た。A battery B7 was produced in the same manner as in Examples 1 to 9 except that this powder was used as the hydrogen storage material.

【００５４】（比較例８） ロール周速度を１５００ｃｍ／秒とし、アニール温度を
９００°Ｃとしたこと以外は実施例１〜９と同様にし
て、平均粒径が７０μｍ、平均厚みが０．０６ｍｍ、開
放面側の結晶粒の大きさの最大が５μｍ、ロール面側の
結晶粒の大きさの最小が０．２μｍの粉末を作製した。(Comparative Example 8) An average particle size of 70 µm and an average thickness of 0.06 mm were obtained in the same manner as in Examples 1 to 9 except that the roll peripheral velocity was 1500 cm / sec and the annealing temperature was 900 ° C. A powder having a maximum crystal grain size of 5 μm on the open surface side and a minimum crystal grain size of 0.2 μm on the roll surface side was produced.

【００５５】水素吸蔵材としてこの粉末を使用したこと
以外は実施例１〜９と同様にして、電池Ｂ８を作製し
た。A battery B8 was produced in the same manner as in Examples 1 to 9 except that this powder was used as the hydrogen storage material.

【００５６】（比較例９） ロール周速度を３０００ｃｍ／秒（ロール径：１５０ｍ
ｍ）とし、アニール温度を９００°Ｃとしたこと以外は
実施例１〜９と同様にして、平均粒径が５５μｍ、平均
厚みが０．０４ｍｍ、開放面側の結晶粒の大きさの最大
が２μｍ、ロール面側の結晶粒の大きさの最小が０．２
μｍの粉末を作製した。なお、ロール周速度を３０００
ｃｍ／秒と高速にしたため、平均粒径７０μｍのものは
得られなかった。(Comparative Example 9) Roll peripheral speed was 3000 cm / sec (roll diameter: 150 m)
m) and the annealing temperature was 900 ° C.
Similar to Examples 1 to 9 , the average grain size was 55 μm, the average thickness was 0.04 mm, the maximum grain size on the open side was 2 μm, and the minimum grain size on the roll side was 0. .2
A μm powder was prepared. The roll peripheral speed is 3000
Since the speed was as high as cm / sec, a particle having an average particle size of 70 μm could not be obtained.

【００５７】水素吸蔵材としてこの粉末を使用したこと
以外は実施例１〜９と同様にして、電池Ｂ９を作製し
た。A battery B9 was produced in the same manner as in Examples 1 to 9 except that this powder was used as the hydrogen storage material.

【００５８】（比較例１０） ロール周速度を５０００ｃｍ／秒（ロール径：１５０ｍ
ｍ）とし、アニール温度を９００°Ｃとしたこと以外は
実施例１〜９と同様にして、平均粒径が４８μｍ、平均
厚みが０．０３ｍｍ、開放面側の結晶粒の大きさの最大
が２μｍ、ロール面側の結晶粒の大きさの最小が０．１
５μｍの粉末を作製した。なお、ロール周速度を５００
０ｃｍ／秒と高速にしたため、平均粒径７０μｍのもの
は得られなかった。(Comparative Example 10) Roll peripheral speed was 5000 cm / sec (roll diameter: 150 m)
m) and the annealing temperature was 900 ° C.
Similar to Examples 1 to 9 , the average grain size was 48 μm, the average thickness was 0.03 mm, the maximum grain size on the open side was 2 μm, and the minimum grain size on the roll side was 0. .1
A 5 μm powder was made. In addition, roll peripheral speed is 500
Since the speed was set to 0 cm / sec, the average particle size of 70 μm could not be obtained.

【００５９】水素吸蔵材としてこの粉末を使用したこと
以外は実施例１〜９と同様にして、電池Ｂ１０を作製し
た。A battery B10 was produced in the same manner as in Examples 1 to 9 except that this powder was used as the hydrogen storage material.

【００６０】比較例１〜１０における合金作製条件（ロ
ール周速度及びアニール温度）、作製した合金粉末の平
均粒径、薄帯の厚み、結晶粒の大きさの最大及び最小
を、表２にまとめて示す。Table 2 shows the alloy production conditions (roll peripheral speed and annealing temperature), the average grain size of the produced alloy powder, the thickness of the ribbon, and the maximum and minimum of the grain size in Comparative Examples 1 to 10. Indicate.

【００６１】[0061]

【表２】 [Table 2]

【００６２】〔充放電サイクル初期の高率放電容量〕電
池Ａ１〜Ａ１３及び電池Ｂ１〜Ｂ１０を、室温（約２５
°Ｃ）にて１２０ｍＡで１６時間充電した後、６０°Ｃ
にて１２０ｍＡで０．９５Ｖまで放電して活性化処理し
た。[High rate discharge capacity at the beginning of charge / discharge cycle]
After charging for 16 hours at 120mA at 60 ° C
At 120 mA, it was discharged to 0.95 V for activation treatment.

【００６３】次いで、各電池を、１２００ｍＡで１．１
時間充電した後、４．８Ａで０．９５Ｖまで放電して、
高率放電容量を求めた。各電池３個について高率放電容
量を測定し、それらの平均を各電池の高率放電容量とし
た。結果を先の表１又は表２に示す。Next, each battery was set to 1.1 at 1200 mA.
After charging for an hour, discharge to 0.95V at 4.8A,
The high rate discharge capacity was determined. The high rate discharge capacity was measured for each of the three batteries, and the average thereof was used as the high rate discharge capacity of each battery. The results are shown in Table 1 or Table 2 above.

【００６４】〔サイクル寿命〕電池Ａ１〜Ａ１３及び電
池Ｂ１〜Ｂ１０について、先と同じ条件で活性化処理し
た後、室温にて、１２００ｍＡで１．１時間充電し、１
時間休止した後、１２００ｍＡで１．０Ｖまで放電する
工程を１サイクルとする充放電サイクル試験を行い、各
電池のサイクル寿命を調べた。各電池１０個についてサ
イクル寿命を求め、最短寿命のものと最長寿命のものを
除く８個についての平均を各電池のサイクル寿命とし
た。サイクル寿命は、電池容量が９６０ｍＡｈ以下に下
がるまでのサイクル数（回）として求めた。結果を先の
表１又は表２に示す。[Cycle Life] The batteries A1 to A13 and the batteries B1 to B10 were activated under the same conditions as described above, and then charged at 1200 mA for 1.1 hours at room temperature.
After pausing for a period of time, a charge / discharge cycle test in which one cycle is a process of discharging at 1200 mA to 1.0 V was performed to examine the cycle life of each battery. The cycle life of each of the 10 batteries was determined, and the average of 8 batteries excluding the one having the shortest life and the one having the longest life was taken as the cycle life of each battery. The cycle life was determined as the number of cycles (times) until the battery capacity dropped to 960 mAh or less. The results are shown in Table 1 or Table 2 above.

【００６５】表１に示す電池Ａ１〜Ａ１３は、充放電サ
イクル初期の高率放電特性に優れるとともに、サイクル
寿命が長いのに対して、表２に示す電池Ｂ１〜Ｂ１０は
充放電サイクル初期の高率放電特性に劣るか、サイクル
寿命が短いか、或いはこれらの両方に問題がある。The batteries A1 to A13 shown in Table 1 are excellent in high rate discharge characteristics at the beginning of the charge / discharge cycle and have a long cycle life, whereas the batteries B1 to B10 shown in Table 2 are high at the beginning of the charge / discharge cycle. There are problems with inferior rate discharge characteristics, short cycle life, or both.

【００６６】電池Ａ１〜Ａ１３が充放電サイクル初期の
高率放電特性に優れ、しかも長寿命であるのは、負極に
使用した水素吸蔵合金にＭｎ等の偏析が少なく、且つ過
小又は過大な結晶粒が存在しないことによるものと考え
られる。The batteries A1 to A13 are excellent in high rate discharge characteristics in the early stage of charge / discharge cycle and have a long life because the hydrogen storage alloy used for the negative electrode has little segregation of Mn and the like and has an excessively small or large crystal grain. Is considered to be due to the absence of.

【００６７】電池Ｂ１は、サイクル寿命は長いものの、
充放電サイクル初期の高率放電容量が小さい。これは、
Ｍｎの分布が均一化されて偏析が解消した上に、結晶粒
が大きくなり過ぎたために、水素吸蔵合金が割れにくく
なったためと考えられる。Although the battery B1 has a long cycle life,
The high rate discharge capacity at the beginning of the charge / discharge cycle is small. this is,
It is considered that the hydrogen storage alloy became hard to crack because the distribution of Mn was made uniform to eliminate the segregation and the crystal grains became too large.

【００６８】電池Ｂ２は、充放電サイクル初期の高率放
電容量は大きいものの、サイクル寿命が短い。これは、
開放面側は割れ易いために活性化し易いが、ロール面側
は割れにくいために活性化しにくいので、開放面側の充
放電深度が深くなり、水素吸蔵合金がこなごなに微粉化
したためと考えられる。The battery B2 has a large high rate discharge capacity at the beginning of the charge / discharge cycle, but has a short cycle life. this is,
It is considered that the open surface side is easily cracked and activated, but the roll surface side is hard to be cracked and thus hard to be activated, so that the charge / discharge depth on the open surface side is deep and the hydrogen storage alloy is finely pulverized.

【００６９】電池Ｂ３は、充放電サイクル初期の高率放
電容量は大きいものの、サイクル寿命が短い。これは、
アニール温度が低過ぎたために活性化が不十分な部分が
存在し、活性化した部分の充放電深度が深くなり、水素
吸蔵合金が微粉化したためと考えられる。Battery B3 has a large high rate discharge capacity at the beginning of the charge / discharge cycle, but has a short cycle life. this is,
It is considered that there was a portion where activation was insufficient because the annealing temperature was too low, and the charge and discharge depth of the activated portion became deep, and the hydrogen storage alloy was pulverized.

【００７０】電池Ｂ４は、充放電サイクル初期の高率放
電容量が小さく、サイクル寿命が短い。充放電サイクル
初期の高率放電容量が小さいのは、アニール温度が合金
の融点に近づいたため、水素吸蔵合金が結晶粒界で一部
再溶解し、非常に割れにくくなって、活性化しにくくな
ったためであり、またサイクル寿命が短いのは、活性化
しにくくなったことに伴い水素吸蔵合金の利用効率が低
下したためと考えられる。Battery B4 has a small high rate discharge capacity at the beginning of the charge / discharge cycle and a short cycle life. The high rate discharge capacity at the beginning of the charge / discharge cycle is small because the annealing temperature was close to the melting point of the alloy, and the hydrogen storage alloy was partially redissolved at the crystal grain boundaries, making it very difficult to crack and difficult to activate. The reason why the cycle life is short is considered to be that the utilization efficiency of the hydrogen storage alloy is lowered due to the difficulty of activation.

【００７１】電池Ｂ５は、充放電サイクル初期の高率放
電容量は大きいものの、サイクル寿命が短い。サイクル
寿命が短いのは、結晶粒は大きいものの、アニール処理
していないために水素吸蔵合金中にＭｎの偏析が存在す
るためである。Battery B5 has a large high rate discharge capacity at the beginning of the charge / discharge cycle, but has a short cycle life. The reason why the cycle life is short is that segregation of Mn is present in the hydrogen storage alloy because the crystal grains are large but are not annealed.

【００７２】電池Ｂ６は、充放電サイクル初期の高率放
電容量は大きいものの、サイクル寿命が短い。これは、
開放面側は割れ易いために活性化し易いが、ロール面側
は割れにくいために活性化しにくいので、開放面側の充
放電深度が深くなり、水素吸蔵合金がこなごなに微粉化
したためと考えられる。Battery B6 has a large high rate discharge capacity at the beginning of the charge / discharge cycle, but has a short cycle life. this is,
It is considered that the open surface side is easily cracked and activated, but the roll surface side is hard to be cracked and thus hard to be activated, so that the charge / discharge depth on the open surface side is deep and the hydrogen storage alloy is finely pulverized.

【００７３】電池Ｂ７は、充放電サイクル初期の高率放
電容量が小さく、サイクル寿命が短い。サイクル寿命が
短いのは、アトマイズ凝固品は粒度分布にバラツキが大
きいため、アニール処理しても粒径により結晶粒の大き
さが異なり、特に３０μｍの小さい粒子の活性化が悪
く、合金粒子全体としての利用効率が悪いためと考えら
れる。Battery B7 has a small high rate discharge capacity at the beginning of the charge / discharge cycle and a short cycle life. The cycle life is short because the atomized solidified product has a large variation in the particle size distribution, and therefore the size of the crystal grains varies depending on the particle size even after annealing, especially the activation of small particles of 30 μm is poor, and as a whole alloy particles It is thought that this is because the usage efficiency of is poor.

【００７４】電池Ｂ８では、合金粒子のロール面側が
（ｈｋ０）面に強い選択配向性を有しているため、アニ
ール処理によりロール面側の結晶粒の大きさの最小が
０．２μｍまで大きくなってはいても、充分な活性化度
が得られない。このため、高率放電容量が小さい。ま
た、電池Ｂ８では、平均粒径７０μｍの合金粉末が使用
されているが、薄帯の厚みが０．０６ｍｍ（６０μｍ）
と薄いために、扁平形状の粒子が多く、合金粒子間の接
触抵抗が大きい。このため、合金粒子全体としての利用
効率が悪く、サイクル寿命が短い。In Battery B8, since the roll surface side of the alloy particles has a strong selective orientation on the (hk0) plane, the minimum grain size of the crystal particles on the roll surface side is annealed.
Even if it is increased to 0.2 μm, a sufficient degree of activation cannot be obtained. Therefore, the high rate discharge capacity is small. Further, in the battery B8, alloy powder having an average particle size of 70 μm is used, but the thickness of the ribbon is 0.06 mm (60 μm).
Since it is thin, there are many flat particles, and the contact resistance between alloy particles is large. Therefore, the utilization efficiency of the alloy particles as a whole is poor and the cycle life is short.

【００７５】電池Ｂ９及び電池Ｂ１０では、電池Ｂ８で
使用した薄帯よりさらに薄い薄帯を粉砕して得た合金粉
末が使用されているため、電池Ｂ８よりも高率放電容量
が小さく、且つサイクル寿命も短い。In the batteries B9 and B10, alloy powder obtained by crushing a ribbon thinner than the ribbon used in the battery B8 is used, and therefore, the high-rate discharge capacity is smaller than that of the battery B8 and the cycle is longer. It has a short life.

【００７６】〈Ｍｍ・Ｎｉ・Ｃｏ・Ａｌ・Ｍｎ合金のＣ
ｏ含有量と充放電サイクル初期の高率放電容量及びサイ
クル寿命の関係〉合金成分金属中のＣｏ量を種々変えた
こと以外は実施例８（ロール周速度：３００ｃｍ／秒；
アニール温度：９００°Ｃ）と同様にして組成式：Ｍｍ
Ｎｉ_4.2-y Ｃｏ_y Ａｌ_0.3 Ｍｎ_0.5 （ｙ＝０．３、０．
４、０．５、０．６、０．７、０．９又は１．０）で表
される７種の水素吸蔵合金粉末（平均粒径：７０μｍ）
を作製した。<C of Mm / Ni / Co / Al / Mn alloy
Relationship between o content and high rate discharge capacity at the beginning of charge / discharge cycle and cycle life> Example 8 (roll peripheral speed: 300 cm / sec; except that the amount of Co in the alloy component metal was changed variously).
Similar to the annealing temperature: 900 ° C), the composition formula: Mm
Ni _4.2-y Co _y Al _0.3 Mn _0.5 (y = 0.3, 0.
4, 0.5, 0.6, 0.7, 0.9 or 1.0) 7 kinds of hydrogen storage alloy powder (average particle size: 70 μm)
Was produced.

【００７７】合金作製条件（ロール周速度及びアニール
温度）、作製した合金粉末の平均粒径、薄帯の厚み、結
晶粒の大きさの最大及び最小を、表３にまとめて示す。Table 3 shows the alloy production conditions (roll peripheral speed and annealing temperature), the average grain size of the produced alloy powder, the thickness of the ribbon, and the maximum and minimum of the grain size.

【００７８】[0078]

【表３】 [Table 3]

【００７９】次いで、水素吸蔵材としてこれらの水素吸
蔵合金粉末を使用したこと以外は実施例８と同様にし
て、水素吸蔵合金電極及びニッケル−水素化物アルカリ
蓄電池を作製した。Then, a hydrogen storage alloy electrode and a nickel-hydride alkaline storage battery were prepared in the same manner as in Example 8 except that these hydrogen storage alloy powders were used as the hydrogen storage material.

【００８０】作製した各ニッケル−水素化物アルカリ蓄
電池について、先と同じ条件の高率放電試験及び充放電
サイクル試験を行い、各電池の充放電サイクル初期の高
率放電特性及びサイクル寿命を調べた。結果を先の表３
に示す。表３には、電池Ａ８の結果も表１より転記して
示してある。Each of the nickel-hydride alkaline storage batteries produced was subjected to a high rate discharge test and a charge / discharge cycle test under the same conditions as above, and the high rate discharge characteristics and the cycle life of each battery at the beginning of the charge / discharge cycle were examined. The results are shown in Table 3 above.
Shown in. In Table 3, the result of the battery A8 is also shown by being transferred from Table 1.

【００８１】表３より、Ｍｍ・Ｎｉ・Ｃｏ・Ａｌ・Ｍｎ
合金の場合、充放電サイクル初期の高率放電特性及び充
放電サイクル特性の両方に優れたニッケル−水素化物ア
ルカリ蓄電池を得る上で、Ｍｍ１モル部に対してＣｏを
０．４〜０．９モル部含有するものを使用することが好
ましいことが分かる。From Table 3, Mm, Ni, Co, Al and Mn
In the case of an alloy, in order to obtain a nickel-hydride alkaline storage battery that is excellent in both high rate discharge characteristics and charge / discharge cycle characteristics at the beginning of charge / discharge cycles, 0.4 to 0.9 mol of Co is added to 1 mol part of Mm. It can be seen that it is preferable to use those containing parts.

【００８２】〈Ｍｍ・Ｎｉ・Ｃｏ・Ａｌ・Ｍｎ合金のＮ
ｉ含有量と充放電サイクル初期の高率放電容量及びサイ
クル寿命の関係〉合金成分金属中のＮｉ量を種々変えた
こと以外は実施例８（ロール周速度：３００ｃｍ／秒；
アニール温度：９００°Ｃ）と同様にして、組成式：Ｍ
ｍＮｉ_zＣｏ_0.8 Ａｌ_0.3 Ｍｎ_0.5 （ｚ＝２．６、２．
８、３．２、３．６又は３．８）で表される５種の水素
吸蔵合金粉末（平均粒径：７０μｍ）を作製した。<N of Mm / Ni / Co / Al / Mn Alloy
Relationship between i content and high rate discharge capacity at the beginning of charge / discharge cycle and cycle life> Example 8 (roll peripheral speed: 300 cm / sec; except that the amount of Ni in the alloy component metal was changed variously).
Similar to the annealing temperature: 900 ° C), the composition formula: M
_{mNi z Co 0.8 Al 0.3 Mn 0.5} (z = 2.6,2.
8, 3.2, 3.6 or 3.8) hydrogen storage alloy powders (average particle size: 70 μm) were prepared.

【００８３】次いで、水素吸蔵材としてこれらの水素吸
蔵合金粉末を使用したこと以外は実施例１〜９と同様に
して、水素吸蔵合金電極及びニッケル−水素化物アルカ
リ蓄電池を作製した。Then, a hydrogen storage alloy electrode and a nickel-hydride alkaline storage battery were prepared in the same manner as in Examples 1 to 9 except that these hydrogen storage alloy powders were used as the hydrogen storage material.

【００８４】合金作製条件（ロール周速度及びアニール
温度）、作製した合金粉末の平均粒径、薄帯の厚み、結
晶粒の大きさの最大及び最小を、表４にまとめて示す。Table 4 shows the alloy production conditions (roll peripheral speed and annealing temperature), the average grain size of the produced alloy powder, the thickness of the ribbon, and the maximum and minimum of the grain size.

【００８５】[0085]

【表４】 [Table 4]

【００８６】作製した各ニッケル−水素化物アルカリ蓄
電池について、先と同じ条件で高率放電試験及び充放電
サイクル試験を行い、各電池の充放電サイクル初期の高
率放電特性及びサイクル寿命を調べた。結果を先の表４
に示す。表４には、電池Ａ８の結果も表１より転記して
示してある。A high-rate discharge test and a charge-discharge cycle test were performed on each of the prepared nickel-hydride alkaline storage batteries under the same conditions as above, and the high-rate discharge characteristics and the cycle life of each battery at the initial stage of the charge-discharge cycle were examined. The results are shown in Table 4 above.
Shown in. In Table 4, the result of Battery A8 is also shown by being transferred from Table 1.

【００８７】表４より、Ｍｍ・Ｎｉ・Ｃｏ・Ａｌ・Ｍｎ
合金の場合、充放電サイクル初期の高率放電特性及び充
放電サイクル特性の両方に優れたニッケル−水素化物ア
ルカリ蓄電池を得る上で、Ｍｍ１モル部に対してＮｉを
２．８〜３．６モル部含有するＭｍ・Ｎｉ・Ｃｏ・Ａｌ
・Ｍｎ合金を使用することが好ましいことが分かる。From Table 4, Mm / Ni / Co / Al / Mn
In the case of an alloy, in order to obtain a nickel-hydride alkaline storage battery that is excellent in both high rate discharge characteristics and charge / discharge cycle characteristics in the early stages of charge / discharge cycles, 2.8 to 3.6 mol of Ni relative to 1 mol part of Mm. Mm / Ni / Co / Al content
-It turns out that it is preferable to use a Mn alloy.

【００８８】〈合金粉末の平均粒径と電池内圧特性の関
係〉合金成分金属（いずれも純度９９．９％以上）を秤
取して混合し、真空下で高周波溶解炉にて溶解した後、
単ロール法（ロール径：３５０ｍｍ）によりロール周速
度３００ｃｍ／秒で冷却して、組成式：ＭｍＮｉ_3.1 Ｃ
ｏ_0.8 Ａｌ_0.3 Ｍｎ_0.5 で表される薄帯状の希土類・ニ
ッケル系水素吸蔵合金を作製した。<Relationship Between Average Particle Diameter of Alloy Powder and Battery Internal Pressure Characteristic> Alloy component metals (each having a purity of 99.9% or more) are weighed and mixed, and after melting in a high frequency melting furnace under vacuum,
A single roll method (roll diameter: 350 mm) was used to cool at a roll peripheral speed of 300 cm / sec, and the composition formula: MmNi _3.1 C
A ribbon-shaped rare earth / nickel-based hydrogen storage alloy represented by o _0.8 Al _0.3 Mn _0.5 was prepared.

【００８９】次いで、この薄帯状の希土類・ニッケル系
水素吸蔵合金を９００°Ｃで、Ａｒガス中にて６時間ア
ニール処理した後、不活性ガス（Ａｒガス）雰囲気下に
おいて機械的に粉砕して、開放面側の結晶粒の大きさの
最大が１３μｍ、ロール面側の結晶粒の大きさの最小が
０．２５μｍ、薄帯の平均厚みが０．２３ｍｍである、
種々の平均粒径の水素吸蔵合金粉末を作製した。Next, this ribbon-shaped rare earth / nickel-based hydrogen storage alloy was annealed at 900 ° C. in Ar gas for 6 hours, and then mechanically ground in an inert gas (Ar gas) atmosphere. The maximum crystal grain size on the open surface side is 13 μm, the minimum crystal grain size on the roll surface side is 0.25 μm, and the average thickness of the ribbon is 0.23 mm.
Hydrogen storage alloy powders having various average particle diameters were produced.

【００９０】これらの水素吸蔵合金粉末を水素吸蔵材と
して使用したこと以外は実施例１〜９と同様にして、Ａ
Ａサイズの正極支配型のニッケル・水素化物アルカリ蓄
電池（電池容量：１２００ｍＡｈ±１０ｍＡｈ）Ａ１４
〜Ａ２５及びＢ１１〜Ｂ１４を作製した。なお、電池Ａ
２０〜Ａ２５及びＢ１３，Ｂ１４は、アニール処理した
薄帯状の希土類・ニッケル系水素吸蔵合金を、機械的に
粉砕した後、さらにｐＨ０．５の塩酸水溶液に浸漬して
攪拌し、液のｐＨが７になった時点で取り出し、純水に
て洗浄し、乾燥したものを水素吸蔵材として使用して作
製した電池である。A was prepared in the same manner as in Examples 1 to 9 except that these hydrogen storage alloy powders were used as the hydrogen storage material.
A size positive electrode dominant nickel-hydride alkaline storage battery (battery capacity: 1200 mAh ± 10 mAh) A14
-A25 and B11-B14 were produced. Battery A
Nos. 20 to A25 and B13 and B14 were obtained by mechanically crushing annealed ribbon-shaped rare earth / nickel-based hydrogen storage alloys, further immersing them in a hydrochloric acid aqueous solution having a pH of 0.5, and stirring them so that the solution had a pH of 7 It is a battery manufactured by using the hydrogen storage material that has been taken out, washed with pure water, and dried.

【００９１】また、単ロール法に代えて通常凝固法を使
用して同組成の塊状の希土類・ニッケル系水素吸蔵合金
を作製し、この合金を９００°Ｃで６時間アニール処理
した後、機械的に粉砕し、篩にかけて、種々の平均粒径
の水素吸蔵合金粉末を作製し、上記と同様にして、電池
Ｂ１５〜Ｂ１９を作製した。Further, instead of the single roll method, a normal solidification method was used to produce a massive rare earth / nickel based hydrogen storage alloy of the same composition, and this alloy was annealed at 900 ° C. for 6 hours and then mechanically treated. The powder was pulverized and sieved to prepare hydrogen storage alloy powders having various average particle sizes, and batteries B15 to B19 were prepared in the same manner as above.

【００９２】〔電池内圧特性〕電池Ａ１４〜Ａ２５及び
Ｂ１１〜Ｂ１９を、室温（約２５°Ｃ）にて１２０ｍＡ
で１６時間充電した後、６０°Ｃにて１２０ｍＡで０．
９５Ｖまで放電して活性化処理した。[Battery Internal Pressure Characteristic] Batteries A14 to A25 and B11 to B19 were 120 mA at room temperature (about 25 ° C).
After charging for 16 hours at 60 ° C, 120 mA at 60 ° C.
It was discharged to 95 V and activated.

【００９３】次いで、各電池の缶底に圧力計を取り付け
た後、室温にて１２００ｍＡ（１Ｃ）で充電し、電池内
圧が１０ｋｇ／ｃｍ² に上昇するまでの充電時間（分）
を求めた。各電池それぞれ４個についてこの充電時間を
求め、４つの充電時間の平均でもって、各電池の電池内
圧特性を評価した。各電池に使用した合金粉末の平均粒
径（μｍ）及び充電時間の平均（分）を表５に示す。酸
液に浸漬して表面処理した合金粉末の平均粒径は、表面
処理後の平均粒径である。Then, after attaching a pressure gauge to the bottom of each battery, the battery was charged at 1200 mA (1C) at room temperature, and the charging time (min) until the battery internal pressure rose to 10 kg / cm ²
I asked. The charging time was determined for each of the four batteries, and the battery internal pressure characteristics of each battery were evaluated by the average of the four charging times. Table 5 shows the average particle size (μm) of the alloy powder used for each battery and the average charging time (minutes). The average particle size of the alloy powder that has been surface-treated by immersing it in an acid solution is the average particle size after the surface treatment.

【００９４】[0094]

【表５】 [Table 5]

【００９５】表５に示すように、電池Ａ１４〜Ａ２５
は、電池Ｂ１１〜Ｂ１９に比べて、内圧が１０ｋｇ／ｃ
ｍ² に達するまでの充電時間が長く、電池内圧特性に優
れている。この結果と先の結果とを総合すると、ロール
面側の結晶粒の大きさの最小が０．２μｍ以上、開放面
側の結晶粒の大きさの最大が２０μｍ以下である、単ロ
ール法により作製された平均厚み０．０８〜０．３５ｍ
ｍの薄帯状の希土類・ニッケル系水素吸蔵合金を、粉砕
して得た平均粒径２５〜７０μｍの合金粉末を水素吸蔵
材として使用することにより、充放電サイクル初期の高
率放電特性及び充放電サイクル特性のみならず、電池内
圧特性にも優れる金属−水素化物アルカリ蓄電池をあた
える水素吸蔵合金電極が得られることが分かる。As shown in Table 5, batteries A14 to A25
Has an internal pressure of 10 kg / c compared to batteries B11 to B19.
The charging time to reach m ² is long and the battery internal pressure characteristics are excellent. Combining this result with the previous result, the single-roll method was used in which the minimum crystal grain size on the roll surface side was 0.2 μm or more and the maximum crystal grain size on the open surface side was 20 μm or less. Average thickness 0.08-0.35m
By using an alloy powder having an average particle size of 25 to 70 μm obtained by crushing a ribbon-shaped rare earth / nickel-based hydrogen storage alloy of m as a hydrogen storage material, high rate discharge characteristics at the beginning of a charge / discharge cycle and charge / discharge It can be seen that a hydrogen storage alloy electrode that can provide a metal-hydride alkaline storage battery that is excellent not only in cycle characteristics but also in battery internal pressure characteristics can be obtained.

【００９６】なお、使用した合金粉末の平均粒径が２０
μｍの電池Ｂ１２の電池内圧特性が良くないのは、表面
処理により酸化物が除去されたために合金粒子表面が平
滑化して合金粒子間の接触がさらに悪くなり、その結果
合金粉末の一部しか反応に関与できなくなったために、
反応熱が高くなり、水素が解離し易くなったことによる
ものと推察される。The alloy powder used had an average particle size of 20.
The battery internal pressure characteristic of the battery B12 of μm is not good because the surface of the alloy particles was smoothed because the oxide was removed by the surface treatment and the contact between the alloy particles was further deteriorated. As a result, only a part of the alloy powder reacted. Because I can no longer be involved in
It is presumed that this is because the heat of reaction became high and hydrogen was easily dissociated.

【００９７】また、使用した合金粉末の平均粒径が８０
μｍの電池Ｂ１１の電池内圧特性が良くないのは、表面
処理により酸化物が除去されたために合金粒子表面の凹
凸が減少して合金粉末の比表面積がさらに小さくなり、
その限られた小さな表面で反応が行われたために、反応
熱が高くなり、水素が解離し易くなったことによるもの
と推察される。The alloy powder used had an average particle size of 80.
The reason why the battery internal pressure characteristic of the battery B11 of μm is not good is that since the oxide is removed by the surface treatment, the irregularities on the surface of the alloy particles are reduced and the specific surface area of the alloy powder is further reduced.
It is speculated that this is because the reaction heat was increased and the hydrogen was easily dissociated because the reaction was carried out on the limited small surface.

【００９８】電池Ａ１４〜Ａ２５の中でも、特に電池Ａ
２１〜Ａ２５において電池内圧特性の向上が顕著に認め
られる。このことから、電池内圧特性を改善する上で、
薄帯状の合金を粉砕した後、さらに酸液に浸漬して表面
処理して得た平均粒径２５〜６０μｍの合金粉末を水素
吸蔵材として使用することが好ましいことが分かる。な
お、通常凝固品を使用した電池Ｂ１５〜Ｂ１９の電池内
圧特性が良くないのは、通常凝固品は急冷凝固品と比較
してＭｎ等の偏析が大きく、それゆえ割れが生じて合金
の酸化が起こり易く、酸素ガスの消費が速やかに進行し
なかったためと推察される。Among the batteries A14 to A25, especially the battery A
In 21 to A25, the improvement of the battery internal pressure characteristic is remarkably recognized. From this, in improving the battery internal pressure characteristics,
It can be seen that it is preferable to use alloy powder having an average particle diameter of 25 to 60 μm obtained by crushing the ribbon-shaped alloy and then further immersing it in an acid solution for surface treatment as a hydrogen storage material. It should be noted that the batteries B15 to B19 using the normally solidified products have poor battery internal pressure characteristics because the normally solidified products have larger segregation of Mn and the like than the rapidly solidified products, and therefore cracks occur and oxidation of the alloy occurs. It is highly probable that the oxygen gas consumption did not proceed promptly.

【００９９】[0099]

【０１００】[0100]

【発明の効果】本発明電極を負極として使用することに
より、充放電サイクル初期の高率放電特性、充放電サイ
クル特性及び電池内圧特性のいずれにも優れる金属−水
素化物アルカリ蓄電池を得ることが可能になる。 By using the electrode of the present invention as a negative electrode, it is possible to obtain a metal-hydride alkaline storage battery having excellent high rate discharge characteristics at the beginning of charge / discharge cycle, charge / discharge cycle characteristics and battery internal pressure characteristics. Becomes

【図面の簡単な説明】[Brief description of drawings]

【図１】単ロール法により急冷凝固させた後、アニール
処理した水素吸蔵合金の断面に現れる結晶粒の様子を示
す模式図である。FIG. 1 is a schematic view showing a state of crystal grains appearing in a cross section of a hydrogen storage alloy that is annealed after being rapidly solidified by a single roll method.

【図２】単ロール法により急冷凝固させた後、アニール
処理しなかった水素吸蔵合金の断面に現れる結晶粒の様
子を示す模式図である。FIG. 2 is a schematic diagram showing a state of crystal grains appearing in a cross section of a hydrogen storage alloy that has not been annealed after being rapidly solidified by a single roll method.

【符号の説明】[Explanation of symbols]

Ａ アニール処理した薄帯状の水素吸蔵合金 １ 白色部（希土類元素及びコバルト濃度の高い層） ２ 黒色部（希土類元素及びコバルト濃度の低い層） ３ 開放面側Ｏの結晶粒の大きさ ４ ロール面側Ｒの結晶粒の大きさ ５ 薄帯の厚み A Annealed ribbon-shaped hydrogen storage alloy 1 White area (layer with high concentration of rare earth elements and cobalt) 2 Black part (layer with low concentration of rare earth elements and cobalt) 3 Size of crystal grains on open side O 4 Size of crystal grain on roll side R 5 Thickness of ribbon

───────────────────────────────────────────────────── フロントページの続き (72)発明者 東山 信幸 大阪府守口市京阪本通２丁目５番５号 三洋電機株式会社内 (72)発明者 黒田 靖 大阪府守口市京阪本通２丁目５番５号 三洋電機株式会社内 (72)発明者 米津 育郎 大阪府守口市京阪本通２丁目５番５号 三洋電機株式会社内 (72)発明者 西尾 晃治 大阪府守口市京阪本通２丁目５番５号 三洋電機株式会社内 (56)参考文献 特開 平７−268519（ＪＰ，Ａ) 特開 平９−82322（ＪＰ，Ａ) (58)調査した分野(Int.Cl.⁷，ＤＢ名) H01M 4/38 H01M 4/24 - 4/26 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyuki Higashiyama 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Denki Co., Ltd. (72) Yasushi Kuroda 2-5-5 Keihanhondori, Moriguchi-shi, Osaka 5 Sanyo Electric Co., Ltd. (72) Inventor Ikuro Yonezu 2-5-5 Keihan Hondori, Moriguchi City, Osaka Prefecture Sanyo Electric Co., Ltd. (72) Koji Nishio 2-5 Keihan Hondori, Moriguchi City, Osaka Prefecture No. 5 within Sanyo Electric Co., Ltd. (56) Reference JP-A-7-268519 (JP, A) JP-A-9-82322 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 4/38 H01M 4/24-4/26

Claims (2)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】ロール面側の下記に定義する結晶粒の大き
さの最小が０．２μｍ以上、開放面側の下記に定義する
結晶粒の大きさの最大が２０μｍ以下である、単ロール
法により作製された平均厚み０．０８〜０．３５ｍｍ
（但し、０．０８ｍｍ以上、０．２３ｍｍ未満の範囲を
除く）の一般式：ＭｍＲ _x （Ｍｍはミッシュメタル；Ｒ
はＮｉ、Ｃｏ、Ａｌ及びＭｎからなる；ｘは４．４〜
５．２）で表される薄帯状の希土類・ニッケル系水素吸
蔵合金を、粉砕して得た平均粒径２５〜７０μｍの合金
粉末が、水素吸蔵材として使用されていることを特徴と
する金属−水素化物アルカリ蓄電池用の水素吸蔵合金電
極。結晶粒の大きさ：合金中の希土類元素の平均濃度と
比べて希土類元素の濃度が高い層と該濃度が低い層とが
交互に出現する多層構造に於けるこれら二層の厚みの和
をいう。1. A single roll method in which the minimum size of crystal grains defined below on the roll side is 0.2 μm or more and the maximum size of crystal grains defined below on the open side is 20 μm or less. Average thickness of 0.08-0.35mm
(However, if the range is 0.08 mm or more and less than 0.23 mm,
Except) general formula: MmR _x (Mm is misch metal; R
Consists of Ni, Co, Al and Mn; x is 4.4 to
A metal characterized in that an alloy powder having an average particle size of 25 to 70 μm obtained by pulverizing a ribbon-shaped rare earth / nickel-based hydrogen storage alloy represented by 5.2) is used as a hydrogen storage material. -A hydrogen storage alloy electrode for a hydride alkaline storage battery. Grain size: average concentration of rare earth elements in alloy
By comparison, it means the sum of the thicknesses of these two layers in a multi-layer structure in which layers having a high concentration of rare earth elements and layers having a low concentration of the rare earth elements appear alternately. 【請求項２】ロール面側の下記に定義する結晶粒の大き
さの最小が０．２μｍ以上、開放面側の下記に定義する
結晶粒の大きさの最大が２０μｍ以下である、単ロール
法により作製された平均厚み０．０８〜０．３５ｍｍ
（但し、０．０８ｍｍ以上、０．２３ｍｍ未満の範囲を
除く）の一般式：ＭｍＲ _x （Ｍｍはミッシュメタル；Ｒ
はＮｉ、Ｃｏ、Ａｌ及びＭｎからなる；ｘは４．４〜
５．２）で表される薄帯状の希土類・ニッケル系水素吸
蔵合金を、粉砕し、酸液に浸漬することにより表面処理
して得た平均粒径２５〜６０μｍの合金粉末が、水素吸
蔵材として使用されていることを特徴とする金属−水素
化物アルカリ蓄電池用の水素吸蔵合金電極。結晶粒の大
きさ：合金中の希土類元素の平均濃度と比べて希土類元
素の濃度が高い層と同濃度が低い層とが交互に出現する
多層構造に於けるこれら二層の厚みの和をいう。2. A single roll method in which the minimum size of crystal grains defined below on the roll side is 0.2 μm or more and the maximum size of crystal grains defined below on the open side is 20 μm or less. Average thickness of 0.08-0.35mm
(However, if the range is 0.08 mm or more and less than 0.23 mm,
Except) general formula: MmR _x (Mm is misch metal; R
Consists of Ni, Co, Al and Mn; x is 4.4 to
The alloy powder having an average particle diameter of 25 to 60 μm obtained by pulverizing the ribbon-shaped rare earth / nickel-based hydrogen storage alloy represented by 5.2) and immersing it in an acid solution is a hydrogen storage material. A hydrogen storage alloy electrode for a metal-hydride alkaline storage battery, characterized by being used as. Grain size: The sum of the thicknesses of these two layers in a multilayer structure in which layers with a high concentration of rare earth elements and layers with a low concentration of rare earth elements alternately appear compared to the average concentration of rare earth elements in the alloy .