JP2002309327A - Hydrogen storage alloy for electrode, its manufacturing method, hydrogen-storage-alloy electrode, and alkaline storage battery - Google Patents
Hydrogen storage alloy for electrode, its manufacturing method, hydrogen-storage-alloy electrode, and alkaline storage batteryInfo
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- JP2002309327A JP2002309327A JP2001112868A JP2001112868A JP2002309327A JP 2002309327 A JP2002309327 A JP 2002309327A JP 2001112868 A JP2001112868 A JP 2001112868A JP 2001112868 A JP2001112868 A JP 2001112868A JP 2002309327 A JP2002309327 A JP 2002309327A
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- Prior art keywords
- hydrogen storage
- storage alloy
- electrode
- hydrogen
- alloy
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】この発明は、ニッケル−水素
蓄電池等のアルカリ蓄電池及びこのアルカリ蓄電池の負
極に使用される水素吸蔵合金電極、またこの水素吸蔵合
金電極に用いる電極用水素吸蔵合金及びその製造方法に
関するものであり、水素吸蔵合金電極に用いる電極用水
素吸蔵合金を改善して、アルカリ蓄電池における充放電
サイクル特性を向上させるようにした点に特徴を有する
ものである。The present invention relates to an alkaline storage battery such as a nickel-hydrogen storage battery, a hydrogen storage alloy electrode used for a negative electrode of the alkaline storage battery, a hydrogen storage alloy for an electrode used for the hydrogen storage alloy electrode, and production thereof. The present invention relates to a method and is characterized in that a hydrogen storage alloy for an electrode used for a hydrogen storage alloy electrode is improved to improve charge / discharge cycle characteristics in an alkaline storage battery.
【０００２】[0002]
【従来の技術】近年、アルカリ蓄電池として、ニッケル
−カドミウム蓄電池に比べ、高容量であり、環境安全性
にも優れている点からニッケル−水素蓄電池が広く利用
されている。2. Description of the Related Art In recent years, nickel-hydrogen storage batteries have been widely used as alkaline storage batteries because of their higher capacity and superior environmental safety as compared with nickel-cadmium storage batteries.
【０００３】ここで、このようなニッケル−水素蓄電池
においては、水素吸蔵合金を用いた水素吸蔵合金電極を
その負極に使用している。Here, in such a nickel-hydrogen storage battery, a hydrogen storage alloy electrode using a hydrogen storage alloy is used for its negative electrode.
【０００４】そして、水素吸蔵合金電極に用いる水素吸
蔵合金材料としては、一般に、Ｍｍ−Ｎｉ（Ｍｍは希土
類元素の混合物であるミッシュメタル）系のＡＢ5 型の
水素吸蔵合金が用いられている。[0004] Then, as the hydrogen storage alloy material used for the hydrogen absorbing alloy electrode, generally, Mm-Ni (Mm is misch metal is a mixture of rare earth elements) AB 5 type hydrogen storage alloy system is used.
【０００５】また、近年においては、上記のニッケル−
水素蓄電池を様々なポータブル機器の電源に使用するた
めに高容量化が要望され、上記の水素吸蔵合金材料とし
て、ＡＢ2 型のラーベス相系の水素吸蔵合金や、水素吸
蔵能力の高いバナジウムを含むＴｉ−Ｖ−Ｎｉ系やＴｉ
−Ｖ−Ｃｒ系等の体心立方構造の水素吸蔵合金を使用す
ることが検討されている。[0005] In recent years, the nickel-
Is desired Koyo capacity is to use a hydrogen storage battery to the power source of various portable devices, as the hydrogen absorbing alloy materials, including, hydrogen storage alloy of Laves phase system of AB 2 type, high vanadium of hydrogen storage capacity Ti-V-Ni or Ti
Use of a hydrogen-absorbing alloy having a body-centered cubic structure such as a -V-Cr system has been studied.
【０００６】一方、上記のような水素吸蔵合金を用いた
水素吸蔵合金電極をアルカリ蓄電池の負極に使用した場
合、この水素吸蔵合金電極における水素吸蔵合金粒子の
一部がアルカリ電解液によって溶解され、特に、水素吸
蔵能力の高いバナジウムを含むＴｉ−Ｖ−Ｎｉ系やＴｉ
−Ｖ−Ｃｒ系等の体心立方構造の水素吸蔵合金の場合、
ニッケルの量が少ないため、水素吸蔵合金電極の導電性
が低下すると共に、水素吸蔵合金粒子がアルカリ電解液
に溶解されやすくなり、これにより容量が低下する等の
問題があった。On the other hand, when a hydrogen storage alloy electrode using the above-mentioned hydrogen storage alloy is used for a negative electrode of an alkaline storage battery, a part of the hydrogen storage alloy particles in the hydrogen storage alloy electrode is dissolved by an alkaline electrolyte. In particular, Ti-V-Ni containing vanadium having a high hydrogen storage capacity and Ti
In the case of a hydrogen storage alloy having a body-centered cubic structure such as
Since the amount of nickel is small, the conductivity of the hydrogen storage alloy electrode is lowered, and the particles of the hydrogen storage alloy are easily dissolved in the alkaline electrolyte, which causes a problem that the capacity is reduced.
【０００７】このため、特開平９−３１２１５７号公報
や特開平９−２３１９６５号公報等に示されるように、
アルカリ蓄電池の負極に用いる水素吸蔵合金電極に、表
面をニッケルで被覆した水素吸蔵合金粒子を使用するこ
とが提案されている。For this reason, as disclosed in Japanese Patent Application Laid-Open Nos. 9-31157 and 9-231965,
It has been proposed to use hydrogen storage alloy particles whose surface is coated with nickel for a hydrogen storage alloy electrode used as a negative electrode of an alkaline storage battery.
【０００８】しかし、このように表面をニッケルで被覆
した水素吸蔵合金粒子を用いた水素吸蔵合金電極をアル
カリ蓄電池の負極に使用した場合においても、このアル
カリ蓄電池を充放電させると、上記の水素吸蔵合金粒子
に亀裂が生じ、この亀裂によってニッケルで被覆されて
いない部分が露出し、この亀裂部分において水素吸蔵合
金粒子がアルカリ電解液に溶解されて、容量が次第に低
下し、充放電サイクル特性が悪くなるという問題があっ
た。However, even when such a hydrogen storage alloy electrode using the hydrogen storage alloy particles whose surface is coated with nickel is used as a negative electrode of an alkaline storage battery, when the alkaline storage battery is charged and discharged, the above-mentioned hydrogen storage alloy is charged. A crack occurs in the alloy particles, and the portion not covered with nickel is exposed by the crack.At this crack portion, the hydrogen storage alloy particles are dissolved in the alkaline electrolyte, the capacity gradually decreases, and the charge / discharge cycle characteristics are poor. There was a problem of becoming.
【０００９】[0009]
【発明が解決しようとする課題】この発明は、水素吸蔵
合金を用いた水素吸蔵合金電極を、アルカリ蓄電池の負
極に使用した場合における上記のような様々な問題を解
決することを課題とするものであり、水素吸蔵合金電極
に用いる電極用水素吸蔵合金を改善し、このような水素
吸蔵合金電極を負極に用いたアルカリ蓄電池において、
充放電により水素吸蔵合金粒子がアルカリ電解液に溶解
されて、容量が次第に低下するのを抑制し、充放電サイ
クル特性に優れたアルカリ蓄電池が得られるようにする
ことを課題とするものである。SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned various problems when a hydrogen storage alloy electrode using a hydrogen storage alloy is used for a negative electrode of an alkaline storage battery. The hydrogen storage alloy for the electrode used for the hydrogen storage alloy electrode is improved, in an alkaline storage battery using such a hydrogen storage alloy electrode as the negative electrode,
It is an object of the present invention to suppress the hydrogen storage alloy particles from being dissolved in an alkaline electrolyte solution due to charge and discharge and to gradually reduce the capacity, thereby obtaining an alkaline storage battery having excellent charge and discharge cycle characteristics.
【００１０】[0010]
【課題を解決するための手段】この発明における電極用
水素吸蔵合金においては、上記のような課題を解決する
ため、水素吸蔵合金粒子の表面に亀裂を形成し、この水
素吸蔵合金粒子の表面及び亀裂の内部にニッケルを含む
被覆層を設けるようにしたのである。In the hydrogen storage alloy for an electrode according to the present invention, in order to solve the above-mentioned problems, a crack is formed on the surface of the hydrogen storage alloy particles, and the surface of the hydrogen storage alloy particles and The coating layer containing nickel was provided inside the crack.
【００１１】そして、水素吸蔵合金電極に上記のような
電極用水素吸蔵合金を用い、この水素吸蔵合金電極をア
ルカリ蓄電池の負極に使用すると、水素吸蔵合金粒子の
表面及び亀裂の内部に形成された被覆層中におけるニッ
ケルによって水素吸蔵合金電極の導電性が向上し、また
このアルカリ蓄電池を充放電させた場合においても、す
でに亀裂の内部にニッケルを含む被覆層が形成されてい
るため、この亀裂の部分において水素吸蔵合金粒子がア
ルカリ電解液に溶解するのが抑制され、これによりアル
カリ蓄電池の容量が低下するのが防止されて、充放電サ
イクル特性に優れたアルカリ蓄電池が得られるようにな
る。When the above-mentioned hydrogen-absorbing alloy for an electrode is used for the hydrogen-absorbing alloy electrode, and this hydrogen-absorbing alloy electrode is used for the negative electrode of an alkaline storage battery, the hydrogen-absorbing alloy electrode is formed on the surface and inside the crack of the hydrogen-absorbing alloy particle. The nickel in the coating layer improves the conductivity of the hydrogen storage alloy electrode, and even when the alkaline storage battery is charged and discharged, the coating layer containing nickel has already been formed inside the crack. Dissolution of the hydrogen storage alloy particles in the alkaline electrolyte at the portion is suppressed, whereby the capacity of the alkaline storage battery is prevented from being reduced, and an alkaline storage battery having excellent charge / discharge cycle characteristics can be obtained.
【００１２】ここで、この発明において使用する水素吸
蔵合金粒子の種類については特に限定されないが、水素
吸蔵合金成分中におけるニッケルの量が少なく、水素吸
蔵能力の高いバナジウムを含む水素吸蔵合金粒子、特
に、Ｔｉ−Ｖ−Ｎｉ系やＴｉ−Ｖ−Ｃｒ系等の体心立方
構造の水素吸蔵合金粒子を用いた場合に、より十分な効
果が得られる。Here, the type of the hydrogen storage alloy particles used in the present invention is not particularly limited, but the amount of nickel in the hydrogen storage alloy component is small, and the hydrogen storage alloy particles containing vanadium having a high hydrogen storage capacity, particularly When a hydrogen-absorbing alloy particle having a body-centered cubic structure such as Ti-V-Ni or Ti-V-Cr is used, a more sufficient effect can be obtained.
【００１３】そして、上記のように水素吸蔵合金粒子の
表面及び亀裂の内部にニッケルを含む被覆層が形成され
た電極用水素吸蔵合金を製造するにあたっては、例え
ば、水素化により水素吸蔵合金粒子の表面に亀裂を形成
する工程と、無電解めっきにより水素吸蔵合金粒子の表
面及び亀裂の内部にニッケルを含む被覆層を形成する工
程とを行うようにする。[0013] In producing a hydrogen storage alloy for an electrode in which a coating layer containing nickel is formed on the surface and inside the cracks of the hydrogen storage alloy particles as described above, for example, the hydrogen storage alloy particles are formed by hydrogenation. A step of forming a crack on the surface and a step of forming a coating layer containing nickel on the surface of the hydrogen storage alloy particles and inside the crack by electroless plating are performed.
【００１４】ここで、上記のように無電解めっきによっ
て亀裂が形成された水素吸蔵合金粒子の表面及び亀裂の
内部にニッケルを含む被覆層を形成するにあたり、被覆
層を形成する速度が早くなり過ぎると、被覆層が水素吸
蔵合金粒子の表面に先に形成されて亀裂の内部に被覆層
が形成されにくくなるため、被覆層を形成する速度を
０．７μｍ／ｈｒ以下にすることが好ましい。Here, in forming the coating layer containing nickel on the surface of the hydrogen storage alloy particles cracked by electroless plating and inside the crack as described above, the speed of forming the coating layer is too fast. In addition, since the coating layer is formed first on the surface of the hydrogen storage alloy particles and the coating layer is not easily formed inside the crack, it is preferable that the speed of forming the coating layer be 0.7 μm / hr or less.
【００１５】また、水素吸蔵合金粒子の表面及び亀裂の
内部に形成される上記の被覆層にニッケルの他に、コバ
ルト，錫，モリブデン，タングステンから選択される少
なくとも１種の元素が含有されると、これら元素がニッ
ケルと合金化して、被覆層が割れにくくなり、より一層
充放電サイクル特性に優れたアルカリ蓄電池が得られる
ようになる。Further, it is preferable that the coating layer formed on the surface of the hydrogen storage alloy particles and inside the crack contains at least one element selected from cobalt, tin, molybdenum and tungsten in addition to nickel. In addition, these elements are alloyed with nickel, so that the coating layer is hardly cracked, and an alkaline storage battery having more excellent charge / discharge cycle characteristics can be obtained.
【００１６】さらに、上記の被覆層に水素吸蔵合金粒子
におけるニッケル以外の合金成分が含有されるようにす
ると、この合金成分により、水素吸蔵合金粒子の表面に
おける触媒機能が高まり、さらに充放電サイクル特性に
優れたアルカリ蓄電池が得られるようになる。Further, when the coating layer contains an alloy component other than nickel in the hydrogen storage alloy particles, this alloy component enhances the catalytic function on the surface of the hydrogen storage alloy particles and further enhances the charge / discharge cycle characteristics. This makes it possible to obtain an excellent alkaline storage battery.
【００１７】ここで、上記のように被覆層に水素吸蔵合
金粒子におけるニッケル以外の合金成分を含有させるに
あたっては、上記の水素吸蔵合金粒子の表面における酸
化物を除去させた状態で、この水素吸蔵合金粒子の表面
に上記のニッケルを含む被覆層を形成し、その後、この
水素吸蔵合金粒子を不活性雰囲気中において熱処理し、
水素吸蔵合金粒子における合金成分を上記の被覆層中に
拡散させるようにすることができる。また、このように
熱処理を行って、水素吸蔵合金粒子における合金成分を
被覆層中に拡散させると、水素吸蔵合金粒子に対する被
覆層の密着性が高くなって、アルカリ蓄電池における充
放電サイクル特性がさらに向上する。Here, as described above, when the coating layer contains alloy components other than nickel in the hydrogen storage alloy particles, the hydrogen storage alloy particles are removed from the surface of the hydrogen storage alloy particles while removing the oxide. Forming a coating layer containing nickel on the surface of the alloy particles, and then heat-treating the hydrogen storage alloy particles in an inert atmosphere;
The alloy component in the hydrogen storage alloy particles can be diffused into the coating layer. Further, when the heat treatment is performed as described above to diffuse the alloy component in the hydrogen storage alloy particles into the coating layer, the adhesion of the coating layer to the hydrogen storage alloy particles increases, and the charge / discharge cycle characteristics of the alkaline storage battery further increase. improves.
【００１８】[0018]
【実施例】以下、この発明の条件を満たす電極用水素吸
蔵合金を用いて作製した実施例の水素吸蔵合金電極をア
ルカリ蓄電池の負極に使用すると、充放電サイクル特性
に優れたアルカリ蓄電池が得られることを、比較例を挙
げて明らかにする。なお、この発明における電極用水素
吸蔵合金粉末及びその製造方法、並びに水素吸蔵合金電
極及びアルカリ蓄電池は、特に、下記の実施例に示した
ものに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できるものである。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS By using the hydrogen storage alloy electrode of the embodiment prepared using a hydrogen storage alloy for an electrode satisfying the conditions of the present invention as a negative electrode of an alkaline storage battery, an alkaline storage battery having excellent charge / discharge cycle characteristics can be obtained. This will be clarified with reference to a comparative example. In addition, the hydrogen storage alloy powder for an electrode and the method for producing the same, and the hydrogen storage alloy electrode and the alkaline storage battery according to the present invention are not particularly limited to those shown in the following examples, and the scope of the gist thereof is not changed. Can be appropriately changed and implemented.
【００１９】（実施例ａ１〜ａ４）実施例ａ１〜ａ４に
おいては、水素吸蔵合金粒子を得るにあたり、ＴｉとＶ
とＮｉとのモル比が３０：６０：１０になるように混合
し、これをアーク溶解法により溶解して得られた溶湯
を、高速で回転する銅ロール上に落とすことにより急冷
凝固し、薄帯状の組成式がＴｉ30Ｖ60Ｎｉ10になった水
素吸蔵合金を得た。(Examples a1 to a4) In Examples a1 to a4, Ti and V were used to obtain hydrogen storage alloy particles.
And Ni are mixed at a molar ratio of 30:60:10, and the resulting mixture is melted by an arc melting method, and the resulting molten metal is dropped on a high-speed rotating copper roll to rapidly solidify and solidify. A hydrogen storage alloy having a belt-shaped composition formula of Ti 30 V 60 Ni 10 was obtained.
【００２０】次いで、この薄帯状の水素吸蔵合金を圧力
容器に入れ、これに３０気圧の水素を加えて水素化させ
て粉砕し、さらにこれを機械的に粉砕して、平均粒径が
６０μｍになったＴｉ30Ｖ60Ｎｉ10の水素吸蔵合金粒子
を得た。なお、この水素吸蔵合金粒子においては、上記
の水素化による粉砕によって水素吸蔵合金粒子の表面か
ら内部にかけて亀裂が形成されていた。Next, this strip-shaped hydrogen storage alloy is placed in a pressure vessel, hydrogenated at 30 atm is added thereto, hydrogenated and pulverized, and further mechanically pulverized to an average particle diameter of 60 μm. The obtained hydrogen storage alloy particles of Ti 30 V 60 Ni 10 were obtained. In the hydrogen storage alloy particles, cracks were formed from the surface to the inside of the hydrogen storage alloy particles by the pulverization by the hydrogenation.
【００２１】そして、上記の水素吸蔵合金粒子を濃度が
０．１ｍｏｌ／ｌで液温が７０℃の硝酸水溶液中におい
て攪拌させて５分間エッチング処理し、この水素吸蔵合
金粒子の表面における酸化物を除去した後、この水素吸
蔵合金粒子を水洗させた。なお、このように表面におけ
る酸化物を除去した水素吸蔵合金粒子を水洗させると、
この水素吸蔵合金粒子の表面が再度酸化された。Then, the above-mentioned hydrogen-absorbing alloy particles are etched in a nitric acid aqueous solution having a concentration of 0.1 mol / l and a liquid temperature of 70 ° C. for 5 minutes, thereby removing oxides on the surfaces of the hydrogen-absorbing alloy particles. After the removal, the hydrogen storage alloy particles were washed with water. In addition, when the hydrogen storage alloy particles from which the oxide on the surface has been removed are washed with water,
The surfaces of the hydrogen storage alloy particles were oxidized again.
【００２２】次いで、上記の水素吸蔵合金粒子を、硫酸
ニッケルが３０ｇ／ｌ、ホスフィン酸ナトリウムが１０
ｇ／ｌ、クエン酸ナトリウムが１０ｇ／ｌの割合になっ
ためっき液中に加えて無電解めっきを行い、リン（Ｐ）
を含むニッケルＮｉの被覆層を形成するようにした。Next, the hydrogen storage alloy particles were mixed with 30 g / l of nickel sulfate and 10 g of sodium phosphinate.
g / l, 10 g / l of sodium citrate was added to the plating solution to perform electroless plating, and phosphorus (P) was added.
To form a coating layer of nickel Ni containing
【００２３】ここで、上記のように無電解めっきにより
リンを含むニッケルの被覆層を形成するにあたり、実施
例ａ１〜ａ４においては、上記のめっき液の液温及びめ
っき時間を下記の表１に示すように変更し、同表に示す
ように、被覆層の形成速度を、実施例ａ１では０．５μ
ｍ／ｈｒ、実施例ａ２では０．７μｍ／ｈｒ、実施例ａ
３では１．１μｍ／ｈｒ、実施例ａ４では５．５μｍ／
ｈｒにして無電解めっきを行い、それぞれ水素吸蔵合金
粒子の表面に厚みが約０．５μｍになったリンを含むニ
ッケルの被覆層を形成して、各電極用水素吸蔵合金を得
た。なお、このようにして得た各電極用水素吸蔵合金に
おいて、被覆層の形成速度を０．７μｍ／ｈｒ以下にし
た実施例ａ１，ａ２のものにおいては、水素吸蔵合金粒
子の表面から内部にかけて形成された亀裂の内部まで被
覆層が十分に形成されていたが、被覆層の形成速度を早
くした実施例ａ３，ａ４のものにおいては、被覆層が亀
裂の内部の一部にしか形成されていなかった。Here, in forming the nickel-containing layer containing phosphorus by electroless plating as described above, in Examples a1 to a4, the temperature of the plating solution and the plating time are shown in Table 1 below. As shown in the table, the formation rate of the coating layer was set to 0.5 μm in Example a1.
m / hr, 0.7 μm / hr in Example a2, Example a
3 was 1.1 μm / hr, and Example a4 was 5.5 μm / hr.
Then, electroless plating was performed for hrs, and a nickel-containing layer containing phosphorus having a thickness of about 0.5 μm was formed on the surface of each of the hydrogen storage alloy particles to obtain a hydrogen storage alloy for each electrode. In each of the thus obtained hydrogen storage alloys for electrodes, in Examples a1 and a2 in which the formation rate of the coating layer was set to 0.7 μm / hr or less, the formation was performed from the surface to the inside of the hydrogen storage alloy particles. Although the coating layer was sufficiently formed up to the inside of the crack thus formed, the coating layer was formed only in a part of the inside of the crack in Examples a3 and a4 in which the formation speed of the coating layer was increased. Was.
【００２４】そして、上記のようにして得た各電極用水
素吸蔵合金０．１ｇに対してそれぞれ銅粉末を０．３ｇ
加えて混合し、これを円板状に加圧成形して実施例ａ１
〜ａ４の各水素吸蔵合金電極を作製した。Then, 0.3 g of copper powder was added to 0.1 g of the hydrogen storage alloy for each electrode obtained as described above.
Example a1
To a4 were prepared.
【００２５】（比較例１）比較例１においても、上記の
実施例ａ１〜ａ４の場合と同様に、Ｔｉ30Ｖ60Ｎｉ10の
水素吸蔵合金の塊を水素化及び機械的に粉砕して得た平
均粒径が６０μｍになったＴｉ30Ｖ60Ｎｉ10の水素吸蔵
合金粒子を用いるようにした。Comparative Example 1 In Comparative Example 1, as in the case of Examples a1 to a4 above, a lump of the hydrogen absorbing alloy of Ti 30 V 60 Ni 10 was obtained by hydrogenation and mechanical pulverization. The hydrogen storage alloy particles of Ti 30 V 60 Ni 10 having an average particle diameter of 60 μm were used.
【００２６】そして、この比較例１においては、上記の
平均粒径が６０μｍになったＴｉ30Ｖ60Ｎｉ10の水素吸
蔵合金粒子を、上記の実施例ａ１〜ａ４の場合と同様
に、濃度が０．１ｍｏｌ／ｌで液温が７０℃の硝酸水溶
液中において攪拌させて５分間エッチング処理し、この
水素吸蔵合金粒子の表面における酸化物を除去した後、
この水素吸蔵合金粒子を水洗し、この水素吸蔵合金粒子
の表面に被覆層を形成せずに、そのまま電極用水素吸蔵
合金として用いるようにした。In Comparative Example 1, the concentration of the hydrogen storage alloy particles of Ti 30 V 60 Ni 10 having the average particle diameter of 60 μm was the same as in Examples a1 to a4. After stirring in a nitric acid aqueous solution at a liquid temperature of 70 ° C. at 0.1 mol / l for 5 minutes to remove the oxide on the surface of the hydrogen storage alloy particles,
The hydrogen storage alloy particles were washed with water, and used as a hydrogen storage alloy for electrodes without forming a coating layer on the surfaces of the hydrogen storage alloy particles.
【００２７】そして、このようにして得た被覆層が形成
されていない電極用水素吸蔵合金を用いる以外は、上記
の実施例ａ１〜ａ４の場合と同様にして、比較例１の水
素吸蔵合金電極を作製した。The hydrogen storage alloy electrode of Comparative Example 1 was prepared in the same manner as in Examples a1 to a4, except that the thus obtained hydrogen storage alloy for an electrode on which the coating layer was not formed was used. Was prepared.
【００２８】（比較例２）比較例２においては、上記の
実施例ａ１〜ａ４の場合と同様にして得たＴｉ30Ｖ60Ｎ
ｉ10の水素吸蔵合金の塊に対して、水素化による粉砕を
行わずに、機械的な粉砕だけを行って平均粒径が６０μ
ｍになったＴｉ30Ｖ60Ｎｉ10の水素吸蔵合金粒子を得
た。なお、このようにして得た水素吸蔵合金粒子におい
ては、上記の実施例ａ１〜ａ４の場合とは異なり、水素
吸蔵合金粒子の表面に水素化させて粉砕させた場合のよ
うな亀裂は形成されていなかった。Comparative Example 2 In Comparative Example 2, Ti 30 V 60 N was obtained in the same manner as in Examples a1 to a4.
relative mass of the hydrogen storage alloy i 10, without grinding by hydrogenation, an average particle diameter by performing only mechanical grinding 60μ
Thus, hydrogen storage alloy particles of Ti 30 V 60 Ni 10 were obtained. In addition, in the hydrogen storage alloy particles thus obtained, unlike the above-described examples a1 to a4, cracks are formed on the surfaces of the hydrogen storage alloy particles as in the case where the surfaces are hydrogenated and pulverized. I didn't.
【００２９】そして、このように表面に水素化粉砕によ
る亀裂が形成されていない水素吸蔵合金粒子を用いる以
外は、上記の実施例ａ１〜ａ４の場合と同様にしてエッ
チング処理し、水素吸蔵合金粒子の表面における酸化物
を除去した後、この水素吸蔵合金粒子を水洗させた。Then, the etching treatment was carried out in the same manner as in Examples a1 to a4, except that the hydrogen-absorbing alloy particles having no crack formed by hydrogenation pulverization on the surface were used. After removing the oxide on the surface of, the hydrogen storage alloy particles were washed with water.
【００３０】その後は、上記の水素吸蔵合金粒子に対し
て、上記の実施例ａ２の場合と同様に、被覆層の形成速
度を０．７μｍ／ｈｒにして無電解めっきを行い、上記
の水素吸蔵合金粒子の表面にだけ厚みが約０．５μｍに
なったリンを含むニッケルの被覆層が形成された電極用
水素吸蔵合金を得た。Thereafter, the hydrogen storage alloy particles were subjected to electroless plating at a coating layer formation rate of 0.7 μm / hr in the same manner as in Example a2 above, and A hydrogen storage alloy for an electrode was obtained in which a nickel-containing layer containing phosphorus having a thickness of about 0.5 μm was formed only on the surfaces of the alloy particles.
【００３１】そして、このように水素吸蔵合金粒子の表
面にだけ被覆層が形成された電極用水素吸蔵合金を用い
る以外は、上記の実施例ａ１〜ａ４の場合と同様にし
て、比較例２の水素吸蔵合金電極を作製した。Then, in the same manner as in Examples a1 to a4 above, except that the hydrogen storage alloy for an electrode in which the coating layer was formed only on the surface of the hydrogen storage alloy particles was used, A hydrogen storage alloy electrode was produced.
【００３２】次に、図１に示すように、上記のようにし
て作製した実施例ａ１〜ａ４及び比較例１，２の各水素
吸蔵合金電極をそれぞれ負極となる作用極１１に用いる
と共に、正極となる対極１２に水酸化ニッケル極を、参
照極１３に酸化水銀電極を使用し、またアルカリ電解液
１４として３０ｗｔ％のＫＯＨ水溶液を使用し、各試験
用アルカリ蓄電池１０を作製した。Next, as shown in FIG. 1, each of the hydrogen storage alloy electrodes of Examples a1 to a4 and Comparative Examples 1 and 2 prepared as described above was used for the working electrode 11 serving as a negative electrode, and A nickel hydroxide electrode was used as the counter electrode 12, a mercury oxide electrode was used as the reference electrode 13, and a 30 wt% KOH aqueous solution was used as the alkaline electrolyte 14, thereby producing each test alkaline storage battery 10.
【００３３】そして、上記の各試験用アルカリ蓄電池１
０を用い、電極用水素吸蔵合金１ｇあたり１００ｍＡの
電流密度で６時間充電した後、電極用水素吸蔵合金１ｇ
あたり５０ｍＡの電流密度で上記の参照極１３の酸化水
銀電極に対する作用極１１の電位が−０．７５Ｖになる
まで放電し、これを１サイクルとして、１００サイクル
の充放電を行い、この１００サイクル中における最大放
電容量Ｃmax と、１００サイクル目の放電容量Ｃ100 と
を測定し、下記の式により１００サイクル目の容量維持
率を求めた。The test alkaline storage batteries 1 described above are used.
After charging for 6 hours at a current density of 100 mA per 1 g of the hydrogen-absorbing alloy for an electrode, use 1 g of the hydrogen-absorbing alloy for an electrode.
At a current density of 50 mA per unit until the potential of the working electrode 11 with respect to the mercury oxide electrode of the reference electrode 13 becomes -0.75 V. This is defined as one cycle, and 100 cycles of charging and discharging are performed. The maximum discharge capacity C max and the discharge capacity C 100 at the 100th cycle were measured, and the capacity retention rate at the 100th cycle was determined by the following equation.
【００３４】 容量維持率（％）＝（Ｃ100 ／Ｃmax ）×１００Capacity maintenance rate (%) = (C 100 / C max ) × 100
【００３５】そして、上記の実施例ａ２の水素吸蔵合金
電極を用いた試験用アルカリ蓄電池１０における容量維
持率を１００とし、実施例ａ１〜ａ４及び比較例１，２
の各水素吸蔵合金電極を用いた各試験用アルカリ蓄電池
１０における容量維持率の相対指数を、容量維持特性と
して下記の表１に示した。The capacity retention of the test alkaline storage battery 10 using the hydrogen storage alloy electrode of Example a2 was set to 100, and Examples Al to A4 and Comparative Examples 1 and 2 were used.
Table 1 below shows relative indices of the capacity retention ratios of the test alkaline storage batteries 10 using the respective hydrogen storage alloy electrodes as the capacity retention characteristics.
【００３６】[0036]
【表１】 [Table 1]
【００３７】この結果、表面に亀裂が形成された水素吸
蔵合金粒子に対してニッケルを含む被覆層を形成した実
施例ａ１〜ａ４の各水素吸蔵合金電極を用いた試験用ア
ルカリ蓄電池は、表面から内部にかけて亀裂が形成され
た水素吸蔵合金粒子に対してニッケルを含む被覆層が形
成されていない比較例１の水素吸蔵合金電極や、亀裂が
形成されていない水素吸蔵合金粒子の表面にだけニッケ
ルの被覆層を形成した比較例２の水素吸蔵合金電極を用
いた試験用アルカリ蓄電池に比べて、１００サイクル目
の容量維持率が高くなって、充放電サイクル特性が向上
していた。As a result, the test alkaline storage battery using each of the hydrogen storage alloy electrodes of Examples a1 to a4 in which a coating layer containing nickel was formed on the hydrogen storage alloy particles having cracks formed on the surface, The hydrogen storage alloy particles of Comparative Example 1 in which a coating layer containing nickel was not formed on the hydrogen storage alloy particles in which cracks were formed inside, and nickel was formed only on the surfaces of the hydrogen storage alloy particles in which cracks were not formed. Compared with the test alkaline storage battery using the hydrogen storage alloy electrode of Comparative Example 2 in which the coating layer was formed, the capacity retention at the 100th cycle was higher, and the charge / discharge cycle characteristics were improved.
【００３８】特に、被覆層の形成速度を０．７μｍ／ｈ
ｒ以下にして、水素吸蔵合金粒子の表面から内部にかけ
て形成された亀裂の内部まで被覆層が十分に形成された
実施例ａ１，ａ２の水素吸蔵合金電極を用いた試験用ア
ルカリ蓄電池においては、実施例ａ３，ａ４の水素吸蔵
合金電極を用いた試験用アルカリ蓄電池に比べて、１０
０サイクル目の容量維持率がさらに著しく高くなって、
充放電サイクル特性が著しく向上していた。In particular, the formation rate of the coating layer is 0.7 μm / h
In the test alkaline storage batteries using the hydrogen storage alloy electrodes of Examples a1 and a2, the coating layer was sufficiently formed from the surface of the hydrogen storage alloy particles to the inside of the crack formed from the surface to the inside of the hydrogen storage alloy particles. As compared with the test alkaline storage battery using the hydrogen storage alloy electrodes of Examples a3 and a4,
The capacity maintenance rate at the 0th cycle is significantly higher,
The charge-discharge cycle characteristics were significantly improved.
【００３９】（実施例ｂ１〜ｂ３）実施例ｂ１〜ｂ３に
おいても、上記の実施例ａ１〜ａ４の場合と同様に、Ｔ
ｉ 30Ｖ60Ｎｉ10の水素吸蔵合金の塊を水素化及び機械的
に粉砕して得た平均粒径が６０μｍになったＴｉ30Ｖ60
Ｎｉ10の水素吸蔵合金粒子を用い、この水素吸蔵合金粒
子を、濃度が０．１ｍｏｌ／ｌで液温が７０℃の硝酸水
溶液中において攪拌させて５分間エッチング処理し、こ
の水素吸蔵合金粒子の表面における酸化物を除去した
後、この水素吸蔵合金粒子を水洗した。(Examples b1 to b3)
In the same manner as in Examples a1 to a4, T
i 30V60NiTenOf hydrogen storage alloy lump
Ti with an average particle size of 60 μm30V60
NiTenUsing the hydrogen storage alloy particles
A nitric acid solution having a concentration of 0.1 mol / l and a liquid temperature of 70 ° C.
Stir in the solution and etch for 5 minutes.
Of oxides on the surface of hydrogen storage alloy particles
Thereafter, the hydrogen storage alloy particles were washed with water.
【００４０】そして、この水素吸蔵合金粒子に対して無
電解めっきを行ってニッケルを含む被覆層を形成するに
あたり、実施例ｂ１では塩化ニッケルが３０ｇ／ｌ、ヒ
ドラジンが６８ｇ／ｌ、酒石酸ナトリウムが９２ｇ／
ｌ、チオ尿素が０．３ｍｇ／ｌの割合になっためっき液
を用いてニッケルＮｉからなる被覆層を、実施例ｂ２で
は塩化ニッケルが３０ｇ／ｌ、エチレンジアミンが６０
ｇ／ｌ、水酸化ナトリウムが４０ｇ／ｌ、テトラヒドロ
ホウ酸ナトリウムが０．６ｇ／ｌの割合になっためっき
液を用いてホウ素（Ｂ）を含むニッケルＮｉの被覆層
を、実施例ｂ３では硫酸ニッケルが１４ｇ／ｌ、硫酸コ
バルトが１．５ｇ／ｌ、ホスフィン酸ナトリウムが１８
ｇ／ｌ、クエン酸ナトリウムが６０ｇ／ｌ、ホウ酸が３
０ｇ／ｌの割合になっためっき液を用いてリン（Ｐ）を
含むニッケル−コバルトＮｉ−Ｃｏ合金の被覆層を形成
するようにした。Then, to form a coating layer containing nickel by performing electroless plating on the hydrogen storage alloy particles, in Example b1, nickel chloride was 30 g / l, hydrazine was 68 g / l, and sodium tartrate was 92 g. /
1 and a plating solution containing thiourea at a ratio of 0.3 mg / l to form a coating layer made of nickel Ni. In Example b2, nickel chloride was 30 g / l and ethylenediamine was 60
g / l, 40 g / l of sodium hydroxide, and 0.6 g / l of sodium tetrahydroborate using a plating solution containing nickel (Ni) containing boron (B) in Example b3. Nickel 14 g / l, cobalt sulfate 1.5 g / l, sodium phosphinate 18
g / l, sodium citrate 60 g / l, boric acid 3
A coating layer of a nickel-cobalt Ni-Co alloy containing phosphorus (P) was formed using a plating solution having a ratio of 0 g / l.
【００４１】ここで、上記のように無電解めっきにより
各被覆層を形成するにあたり、実施例ｂ１〜ｂ３におい
ては、上記のめっき液の液温及びめっき時間を下記の表
２に示すように調整し、同表に示すように、被覆層の形
成速度を何れも上記の実施例ａ２と同じ０．７μｍ／ｈ
ｒになるようにして、水素吸蔵合金粒子にそれぞれ厚み
が約０．５μｍになった上記の各被覆層を形成して、各
電極用水素吸蔵合金を得た。なお、このようにして被覆
層を形成した場合、上記の実施例ａ２の場合と同様に、
水素吸蔵合金粒子の表面及びその表面から内部にかけて
形成された亀裂の内部まで被覆層が十分に設けられた。Here, in forming each coating layer by electroless plating as described above, in Examples b1 to b3, the solution temperature and the plating time of the plating solution were adjusted as shown in Table 2 below. Then, as shown in the same table, the formation rate of the coating layer was 0.7 μm / h, which is the same as that in Example a2.
r, the above-mentioned coating layers having a thickness of about 0.5 μm were formed on the hydrogen storage alloy particles to obtain hydrogen storage alloys for the respective electrodes. When the coating layer was formed in this manner, similar to the case of the above-mentioned Example a2,
The coating layer was sufficiently provided up to the surface of the hydrogen storage alloy particles and the inside of the crack formed from the surface to the inside.
【００４２】そして、このようにして得た各電極用水素
吸蔵合金を用いる以外は、上記の実施例ａ１〜ａ４の場
合と同様にして、実施例ｂ１〜ｂ３の各水素吸蔵合金電
極を作製した。Each of the hydrogen storage alloy electrodes of Examples b1 to b3 was manufactured in the same manner as in Examples a1 to a4 except that the hydrogen storage alloy for each electrode thus obtained was used. .
【００４３】また、このようにして作製した実施例ｂ１
〜ｂ３の各水素吸蔵合金電極を用い、上記の実施例ａ２
の場合と同様にして、図１に示す各試験用アルカリ蓄電
池１０を作製し、各試験用アルカリ蓄電池１０における
１００サイクル目の容量維持率を上記の実施例ａ２の場
合と同様にして求め、実施例ａ２の水素吸蔵合金電極を
用いた試験用アルカリ蓄電池１０における容量維持率を
１００とし、実施例ｂ１〜ｂ３の各水素吸蔵合金電極を
用いた各試験用アルカリ蓄電池１０における容量維持率
の相対指数を、容量維持特性として下記の表２に示し
た。Example b1 produced in this manner
Example a2 using each of the hydrogen storage alloy electrodes
In the same manner as in the case of the above, each test alkaline storage battery 10 shown in FIG. Relative index of the capacity retention rate of each test alkaline storage battery 10 using each hydrogen storage alloy electrode of Examples b1 to b3, where the capacity retention rate of the test alkaline storage battery 10 using the hydrogen storage alloy electrode of Example a2 is 100. Are shown in Table 2 below as capacity retention characteristics.
【００４４】[0044]
【表２】 [Table 2]
【００４５】この結果、水素化粉砕によって表面から内
部にかけて亀裂が形成された水素吸蔵合金粒子に対し、
被覆層の形成速度を０．７μｍ／ｈｒにしてニッケルを
含む被覆層を形成した実施例ｂ１〜ｂ３の各水素吸蔵合
金電極を用いた試験用アルカリ蓄電池においても、上記
の実施例ａ２の水素吸蔵合金電極を用いた試験用アルカ
リ蓄電池の場合と同様に、１００サイクル目の容量維持
率が非常に高くなり、充放電サイクル特性が著しく向上
していた。特に、ニッケル−コバルト合金の被覆層を形
成した実施例ｂ３の水素吸蔵合金電極を用いた場合に
は、１００サイクル目の容量維持率がさらに高くなっ
て、充放電サイクル特性がさらに向上していた。As a result, the hydrogen-absorbing alloy particles in which cracks were formed from the surface to the inside by the hydropulverization
In the test alkaline storage batteries using the hydrogen storage alloy electrodes of Examples b1 to b3 in which the coating layer containing nickel was formed at a coating layer formation rate of 0.7 μm / hr, the hydrogen storage of Example a2 was also performed. As in the case of the test alkaline storage battery using the alloy electrode, the capacity maintenance ratio at the 100th cycle was extremely high, and the charge / discharge cycle characteristics were significantly improved. In particular, when the hydrogen storage alloy electrode of Example b3 in which the coating layer of the nickel-cobalt alloy was formed was used, the capacity retention rate at the 100th cycle was further increased, and the charge / discharge cycle characteristics were further improved. .
【００４６】なお、上記の実施例ｂ３においては、被覆
層中にニッケルの他にコバルトを含有させてニッケル−
コバルト合金の被覆層を形成するようにしたが、コバル
トに代えて、錫やモリブデンやタングステンを含有させ
て、これらの元素とニッケルとの合金からなる被覆層を
形成した場合においても、同様の効果が得られた。In the embodiment b3, the coating layer contains cobalt in addition to nickel, and
Although a coating layer of a cobalt alloy is formed, the same effect can be obtained when a coating layer made of an alloy of nickel and these elements is formed by containing tin, molybdenum, or tungsten instead of cobalt. was gotten.
【００４７】（実施例ｃ１，ｃ２）実施例ｃ１，ｃ２に
おいても、上記の実施例ａ１〜ａ４の場合と同様に、Ｔ
ｉ 30Ｖ60Ｎｉ10の水素吸蔵合金の塊を水素化及び機械的
に粉砕して得た平均粒径が６０μｍになったＴｉ30Ｖ60
Ｎｉ10の水素吸蔵合金粒子を用い、この水素吸蔵合金粒
子を、濃度が０．１ｍｏｌ／ｌで液温が７０℃の硝酸水
溶液中において攪拌させて５分間エッチング処理し、こ
の水素吸蔵合金粒子の表面における酸化物を除去した。(Examples c1 and c2)
In the same manner as in Examples a1 to a4, T
i 30V60NiTenOf hydrogen storage alloy lump
Ti with an average particle size of 60 μm30V60
NiTenUsing the hydrogen storage alloy particles
A nitric acid solution having a concentration of 0.1 mol / l and a liquid temperature of 70 ° C.
Stir in the solution and etch for 5 minutes.
The oxide on the surface of the hydrogen storage alloy particles was removed.
【００４８】そして、実施例ｃ１，ｃ２においては、上
記のようにエッチング処理した水素吸蔵合金粒子を水洗
したり、空気中に取り出したりすることなく、上澄み液
を排出し、これに硫酸ニッケルが３０ｇ／ｌ、ホスフィ
ン酸ナトリウムが１０ｇ／ｌ、クエン酸ナトリウムが１
０ｇ／ｌの割合になっためっき液を加え、上記の実施例
ａ２の場合と同様に、被覆層の形成速度を０．７μｍ／
ｈｒして無電解めっきを行い、リンを含むニッケルの被
覆層を形成した。In Examples c1 and c2, the supernatant liquid was discharged without washing the hydrogen-absorbing alloy particles etched as described above with water or taking them out into the air. / L, sodium phosphinate 10 g / l, sodium citrate 1
0 g / l of the plating solution was added, and the formation rate of the coating layer was reduced to 0.7 μm / l in the same manner as in Example a2.
After that, electroless plating was performed to form a nickel-containing layer containing phosphorus.
【００４９】なお、このようにして被覆層を形成した場
合、水素吸蔵合金粒子の表面における酸化物が非常に少
ない状態で、水素吸蔵合金粒子の表面及びその表面から
内部にかけて形成された亀裂の内部まで被覆層が十分に
設けられた。When the coating layer is formed in this manner, the surface of the hydrogen-absorbing alloy particles and the inside of the crack formed from the surface to the inside thereof are formed with very little oxide on the surface of the hydrogen-absorbing alloy particles. The coating layer was sufficiently provided up to this point.
【００５０】そして、実施例ｃ１においては、上記のよ
うにして被覆層が形成された水素吸蔵合金粒子をそのま
ま電極用水素吸蔵合金として用いる一方、実施例ｃ２に
おいては、上記のようにして被覆層が形成された水素吸
蔵合金粒子を、アルゴン雰囲気中において７００℃の温
度で熱処理したものを電極用水素吸蔵合金を用いるよう
にした。In Example c1, the hydrogen storage alloy particles on which the coating layer was formed as described above were used as they were as the hydrogen storage alloy for the electrode, while in Example c2, the coating layer was formed as described above. The hydrogen-absorbing alloy particles on which the particles were formed were heat-treated at a temperature of 700 ° C. in an argon atmosphere, and the hydrogen-absorbing alloy for an electrode was used.
【００５１】ここで、実施例ｃ２に示すように、被覆層
が形成された水素吸蔵合金粒子をアルゴン雰囲気中にお
いて７００℃の温度で熱処理すると、上記の水素吸蔵合
金粒子における合金成分が、水素吸蔵合金粒子の表面に
おける酸化物によって抑制されることなく、上記の被覆
層中に拡散されて含有されるようになった。なお、この
ようにして熱処理した後の被覆層における成分の割合を
オージェ分析により測定したところ、被覆層中における
ニッケルの存在比率は４８原子％，ニッケル以外の合金
成分であるチタンの存在比率は１１原子％，バナジウム
の存在比率は２６原子％になっていた。Here, as shown in Example c2, when the hydrogen-absorbing alloy particles on which the coating layer was formed were heat-treated at a temperature of 700 ° C. in an argon atmosphere, the alloy components in the hydrogen-absorbing alloy particles became hydrogen-absorbing. Without being suppressed by the oxide on the surface of the alloy particles, the alloy particles were diffused and contained in the coating layer. When the proportion of the components in the coating layer after the heat treatment was measured by Auger analysis, the proportion of nickel in the coating layer was 48 atomic%, and the proportion of titanium as an alloy component other than nickel was 11%. Atomic% and the abundance ratio of vanadium were 26 atomic%.
【００５２】そして、上記のようにして得た各電極用水
素吸蔵合金を用いる以外は、上記の実施例ａ１〜ａ４の
場合と同様にして、実施例ｃ１，ｃ２の各水素吸蔵合金
電極を作製した。Then, the respective hydrogen storage alloy electrodes of Examples c1 and c2 were prepared in the same manner as in Examples a1 to a4 except that the hydrogen storage alloy for each electrode obtained as described above was used. did.
【００５３】また、このようにして作製した実施例ｃ
１，ｃ２の各水素吸蔵合金電極を用い、上記の実施例ａ
２の場合と同様にして、図１に示す各試験用アルカリ蓄
電池１０を作製し、各試験用アルカリ蓄電池１０におけ
る１００サイクル目の容量維持率を上記の実施例ａ２の
場合と同様にして求め、実施例ａ２の水素吸蔵合金電極
を用いた試験用アルカリ蓄電池１０における容量維持率
を１００とし、実施例ｃ１，ｃ２の各水素吸蔵合金電極
を用いた各試験用アルカリ蓄電池１０における容量維持
率の相対指数を、容量維持特性として下記の表３に示し
た。Example c produced as described above
Example a using the hydrogen storage alloy electrodes 1 and 2
2, each test alkaline storage battery 10 shown in FIG. 1 was prepared, and the capacity maintenance ratio at the 100th cycle in each test alkaline storage battery 10 was obtained in the same manner as in Example a2. The capacity retention rate of the test alkaline storage battery 10 using the hydrogen storage alloy electrode of Example a2 was set to 100, and the relative capacity retention rate of each test alkaline storage battery 10 using each hydrogen storage alloy electrode of Examples c1 and c2. The indices are shown in Table 3 below as capacity retention characteristics.
【００５４】[0054]
【表３】 [Table 3]
【００５５】この結果、実施例ｃ１，ｃ２の各水素吸蔵
合金電極を用いた試験用アルカリ蓄電池においても、上
記の実施例ａ２の水素吸蔵合金電極を用いた試験用アル
カリ蓄電池の場合と同様に、１００サイクル目の容量維
持率が非常に高くなり、充放電サイクル特性が著しく向
上しており、特に、被覆層が形成された水素吸蔵合金粒
子を熱処理して、上記の被覆層中に水素吸蔵合金粒子に
おける合金成分を拡散させて含有させた実施例ｃ２の水
素吸蔵合金電極を用いた場合には、１００サイクル目の
容量維持率がさらに高くなって、充放電サイクル特性が
さらに向上していた。As a result, in the test alkaline storage battery using each of the hydrogen storage alloy electrodes of Examples c1 and c2, as in the case of the test alkaline storage battery using the hydrogen storage alloy electrode of Example a2 described above, The capacity retention ratio at the 100th cycle is extremely high, and the charge / discharge cycle characteristics are significantly improved. In particular, the hydrogen storage alloy particles having the coating layer formed thereon are subjected to a heat treatment so that the hydrogen storage alloy is contained in the coating layer. In the case of using the hydrogen storage alloy electrode of Example c2 in which the alloy component in the particles was diffused and contained, the capacity retention ratio at the 100th cycle was further increased, and the charge / discharge cycle characteristics were further improved.
【００５６】[0056]
【発明の効果】以上詳述したように、この発明において
は、水素吸蔵合金電極における電極用水素吸蔵合金とし
て、水素吸蔵合金粒子の表面に亀裂を形成し、この水素
吸蔵合金粒子の表面及び亀裂の内部にニッケルを含む被
覆層を設けたものを用いるようにしたため、この水素吸
蔵合金電極をアルカリ蓄電池の負極に使用すると、水素
吸蔵合金粒子の表面及び亀裂の内部に形成された被覆層
中におけるニッケルによって水素吸蔵合金電極における
導電性が向上し、また充放電を繰り返した場合において
も、すでに亀裂の内部にニッケルを含む被覆層が形成さ
れているため、この亀裂部分において水素吸蔵合金粒子
がアルカリ電解液に溶解するのが抑制され、アルカリ蓄
電池の容量が低下するのが防止されて、充放電サイクル
特性に優れたアルカリ蓄電池が得られるようになった。As described above in detail, according to the present invention, as a hydrogen storage alloy for an electrode in a hydrogen storage alloy electrode, a crack is formed on the surface of the hydrogen storage alloy particle, and the surface of the hydrogen storage alloy particle and the crack are formed. In order to use a coating layer containing nickel inside, when this hydrogen storage alloy electrode is used for a negative electrode of an alkaline storage battery, in the coating layer formed on the surface of the hydrogen storage alloy particles and inside the cracks Nickel improves the conductivity of the hydrogen-absorbing alloy electrode, and even when charge and discharge are repeated, the nickel-containing coating layer has already been formed inside the crack. Dissolution in the electrolytic solution is suppressed, the capacity of the alkaline storage battery is prevented from lowering, and the battery having excellent charge / discharge cycle characteristics. It came to Li battery can be obtained.
【図１】この発明の実施例及び比較例において使用した
試験用アルカリ蓄電池の概略説明図である。FIG. 1 is a schematic explanatory view of a test alkaline storage battery used in Examples and Comparative Examples of the present invention.
１０ 試験用アルカリ蓄電池 １１ 作用極（水素吸蔵合金電極） １２ 対極 １３ 参照極 １４ アルカリ電解液 DESCRIPTION OF SYMBOLS 10 Test alkaline storage battery 11 Working electrode (hydrogen storage alloy electrode) 12 Counter electrode 13 Reference electrode 14 Alkaline electrolyte
───────────────────────────────────────────────────── フロントページの続き (72)発明者 中村 宏 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 伊勢 忠司 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 藤谷 伸 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 Ｆターム(参考） 4K018 AA08 BC24 KA37 5H028 AA01 BB03 BB06 BB10 EE01 EE08 EE10 HH00 5H050 AA07 BA14 CA03 CB16 DA09 EA03 FA17 FA18 GA10 GA17 GA24 GA25 HA12 HA20 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Hiroshi Nakamura 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Tadashi Ise 2-5-2 Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd. (72) Inventor Shin Fujitani 5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in Sanyo Electric Co., Ltd. 4K018 AA08 BC24 KA37 5H028 AA01 BB03 BB06 BB10 EE01 EE08 EE10 HH00 5H050 AA07 BA14 CA03 CB16 DA09 EA03 FA17 FA18 GA10 GA17 GA24 GA25 HA12 HA20
Claims (10)
れ、この水素吸蔵合金粒子の表面及び亀裂の内部にニッ
ケルを含む被覆層が形成されていることを特徴とする電
極用水素吸蔵合金。1. A hydrogen storage alloy for an electrode, wherein a crack is formed on the surface of the hydrogen storage alloy particle, and a coating layer containing nickel is formed on the surface of the hydrogen storage alloy particle and inside the crack.
において、上記の水素吸蔵合金粒子が合金成分としてバ
ナジウムを含んでいることを特徴とする電極用水素吸蔵
合金。2. The hydrogen storage alloy for an electrode according to claim 1, wherein the hydrogen storage alloy particles contain vanadium as an alloy component.
蔵合金において、上記の水素吸蔵合金粒子の結晶構造が
体心立方構造であることを特徴とする電極用水素吸蔵合
金。3. The hydrogen storage alloy for an electrode according to claim 1, wherein the crystal structure of the hydrogen storage alloy particles is a body-centered cubic structure.
極用水素吸蔵合金において、上記のニッケルを含む被覆
層が無電解めっきによって形成されていることを特徴と
する電極用水素吸蔵合金。4. The hydrogen storage alloy for an electrode according to claim 1, wherein the nickel-containing coating layer is formed by electroless plating. alloy.
極用水素吸蔵合金において、上記のニッケルを含む被覆
層中に、コバルト，錫，モリブデン，タングステンから
選択される少なくとも１種の元素が含有されていること
を特徴とする電極用水素吸蔵合金。5. The hydrogen-absorbing alloy for an electrode according to claim 1, wherein the nickel-containing coating layer includes at least one selected from the group consisting of cobalt, tin, molybdenum, and tungsten. A hydrogen storage alloy for an electrode, comprising an element.
極用水素吸蔵合金において、上記のニッケルを含む被覆
層中に上記の水素吸蔵合金粒子におけるニッケル以外の
合金成分が含有されていることを特徴とする電極用水素
吸蔵合金。6. The hydrogen storage alloy for an electrode according to any one of claims 1 to 5, wherein the nickel-containing coating layer contains an alloy component other than nickel in the hydrogen storage alloy particles. A hydrogen storage alloy for an electrode, comprising:
極用水素吸蔵合金を製造するにあたり、水素化により水
素吸蔵合金粒子の表面に亀裂を形成する工程と、無電解
めっきにより水素吸蔵合金粒子の表面及び亀裂の内部に
ニッケルを含む被覆層を形成する工程とを有することを
特徴とする電極用水素吸蔵合金の製造方法。7. A method for producing the hydrogen storage alloy for an electrode according to claim 1, wherein a step of forming cracks on the surfaces of the hydrogen storage alloy particles by hydrogenation, and a step of forming hydrogen by electroless plating. Forming a coating layer containing nickel on surfaces and inside cracks of the storage alloy particles.
の製造方法において、上記の無電解めっきによる被覆層
の形成速度を０．７μｍ／ｈｒ以下にしたことを特徴と
する電極用水素吸蔵合金の製造方法。8. The method for producing a hydrogen storage alloy for an electrode according to claim 7, wherein the formation rate of the coating layer by the electroless plating is set to 0.7 μm / hr or less. Alloy manufacturing method.
極用水素吸蔵合金を用いたことを特徴とする水素吸蔵合
金電極。9. A hydrogen storage alloy electrode using the hydrogen storage alloy for an electrode according to any one of claims 1 to 6.
を負極に用いたことを特徴とするアルカリ蓄電池。10. An alkaline storage battery using the hydrogen storage alloy electrode according to claim 9 for a negative electrode.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004066421A1 (en) * | 2003-01-20 | 2004-08-05 | Yuasa Corporation | Closed nickel-hydrogen storage battery and its production method |
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| JPH08291391A (en) * | 1995-02-22 | 1996-11-05 | Toyota Central Res & Dev Lab Inc | Surface treatment of hydrogen occlusion alloy material, activation treatment of hydrogen occlusion alloy electrode, activating solution, and hydrogen occlusion alloy electrode having excellent initial activity |
| JPH09176778A (en) * | 1995-10-25 | 1997-07-08 | Mitsubishi Materials Corp | Hydrogen storage alloy |
| JPH09316571A (en) * | 1996-05-22 | 1997-12-09 | Matsushita Electric Ind Co Ltd | Hydrogen storage alloy |
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2001
- 2001-04-11 JP JP2001112868A patent/JP2002309327A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08291391A (en) * | 1995-02-22 | 1996-11-05 | Toyota Central Res & Dev Lab Inc | Surface treatment of hydrogen occlusion alloy material, activation treatment of hydrogen occlusion alloy electrode, activating solution, and hydrogen occlusion alloy electrode having excellent initial activity |
| JPH09176778A (en) * | 1995-10-25 | 1997-07-08 | Mitsubishi Materials Corp | Hydrogen storage alloy |
| JPH09316571A (en) * | 1996-05-22 | 1997-12-09 | Matsushita Electric Ind Co Ltd | Hydrogen storage alloy |
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| WO2004066421A1 (en) * | 2003-01-20 | 2004-08-05 | Yuasa Corporation | Closed nickel-hydrogen storage battery and its production method |
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