JP2003173772A - Hydrogen storage alloy powder for electrode and its manufacturing method - Google Patents
Hydrogen storage alloy powder for electrode and its manufacturing methodInfo
- Publication number
- JP2003173772A JP2003173772A JP2001370468A JP2001370468A JP2003173772A JP 2003173772 A JP2003173772 A JP 2003173772A JP 2001370468 A JP2001370468 A JP 2001370468A JP 2001370468 A JP2001370468 A JP 2001370468A JP 2003173772 A JP2003173772 A JP 2003173772A
- Authority
- JP
- Japan
- Prior art keywords
- hydrogen storage
- alloy powder
- storage alloy
- electrode
- hydrogen
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000000956 alloy Substances 0.000 title claims abstract description 145
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 145
- 238000003860 storage Methods 0.000 title claims abstract description 126
- 239000001257 hydrogen Substances 0.000 title claims abstract description 122
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 122
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 115
- 239000000843 powder Substances 0.000 title claims abstract description 115
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- 239000002253 acid Substances 0.000 claims abstract description 10
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000011259 mixed solution Substances 0.000 claims abstract description 8
- 239000007864 aqueous solution Substances 0.000 claims description 23
- 238000000034 method Methods 0.000 abstract description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 13
- 239000000243 solution Substances 0.000 abstract description 4
- 238000007598 dipping method Methods 0.000 abstract description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 32
- 230000000052 comparative effect Effects 0.000 description 19
- 239000002245 particle Substances 0.000 description 16
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 15
- 229910052759 nickel Inorganic materials 0.000 description 15
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 12
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 12
- 230000000694 effects Effects 0.000 description 10
- 230000001965 increasing effect Effects 0.000 description 10
- 239000000126 substance Substances 0.000 description 10
- 238000003756 stirring Methods 0.000 description 9
- 239000003513 alkali Substances 0.000 description 6
- 239000003054 catalyst Substances 0.000 description 6
- 238000005260 corrosion Methods 0.000 description 6
- 230000007797 corrosion Effects 0.000 description 6
- 239000000203 mixture Substances 0.000 description 5
- 239000006228 supernatant Substances 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 239000008151 electrolyte solution Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- 230000004913 activation Effects 0.000 description 3
- 238000007654 immersion Methods 0.000 description 3
- 239000000696 magnetic material Substances 0.000 description 3
- 238000010298 pulverizing process Methods 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910018007 MmNi Inorganic materials 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 239000011260 aqueous acid Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 230000005307 ferromagnetism Effects 0.000 description 2
- -1 for example Substances 0.000 description 2
- QOSATHPSBFQAML-UHFFFAOYSA-N hydrogen peroxide;hydrate Chemical compound O.OO QOSATHPSBFQAML-UHFFFAOYSA-N 0.000 description 2
- 230000005415 magnetization Effects 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 238000000967 suction filtration Methods 0.000 description 2
- 238000004438 BET method Methods 0.000 description 1
- 229910004247 CaCu Inorganic materials 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 1
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000011362 coarse particle Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000011162 core material Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 210000001787 dendrite Anatomy 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000007772 electroless plating Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000009689 gas atomisation Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052987 metal hydride Inorganic materials 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 238000005549 size reduction Methods 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 125000000542 sulfonic acid group Chemical group 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- 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
Landscapes
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Powder Metallurgy (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、ニッケル水素蓄電
池などに用いられる水素吸蔵合金からなる電極用粉末の
製造方法およびこれにより得られる水素吸蔵合金粉末に
関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an electrode powder made of a hydrogen storage alloy used in nickel-hydrogen storage batteries and the like, and a hydrogen storage alloy powder obtained thereby.
【０００２】[0002]
【従来の技術】水素を可逆的に吸蔵・放出し得る水素吸
蔵合金を用いた電極は、カドミウム電極より大きい理論
容量密度を有し、亜鉛電極のように変形したりデンドラ
イトを形成したりすることがないことから、寿命が長く
無公害である。しかも、エネルギー密度が高いことか
ら、前記電極は、ニッケル水素蓄電池の負極として小型
ポータブル機器用電源などに多用され、今後もその発展
が益々期待されている。2. Description of the Related Art An electrode using a hydrogen storage alloy capable of reversibly storing and releasing hydrogen has a theoretical capacity density larger than that of a cadmium electrode and can be deformed like a zinc electrode or can form dendrites. It has a long service life and is pollution-free. Moreover, since the energy density is high, the electrode is frequently used as a negative electrode of a nickel-hydrogen storage battery in a power source for small portable devices and the like, and further development is expected in the future.
【０００３】ニッケル水素蓄電池は、近年、電気自動車
などの動力電源としても注目を集めており、その場合に
は一層の出力特性の改善、信頼性を確保するための寿命
特性の向上などが強く要望されている。一般に、ニッケ
ル水素蓄電池の初期の出力は低く、これは水素吸蔵合金
負極の初期活性能の低さに起因している。電池の初期の
出力特性が低い場合、出荷前に活性化のためのサイクル
やエージングなどを施す必要があるが、これは製造工程
のコストアップにつながるという大きな問題がある。In recent years, nickel-hydrogen storage batteries have been attracting attention as a power source for electric vehicles, and in that case, further improvement of output characteristics and improvement of life characteristics for securing reliability are strongly demanded. Has been done. Generally, the initial output of a nickel-hydrogen storage battery is low, which is due to the low initial activation capacity of the hydrogen storage alloy negative electrode. When the initial output characteristics of the battery are low, it is necessary to perform a cycle for activation or aging before shipping, but this causes a large problem that the cost of the manufacturing process increases.
【０００４】ニッケル水素蓄電池の負極活物質として
は、一般的にはＣａＣｕ5型の結晶構造を有し、かつ
式：ＭｍＮｉ5（Ｍｍは希土類元素の混合物、Ｎｉの一
部をＣｏ、Ｍｎ、ＡｌおよびＣｕなどで置換。）で表さ
れる合金が広く用いられている。また、電池のさらなる
小型化および軽量化を実現するために、新規な水素吸蔵
合金の研究開発も活発に行われている。製造された水素
吸蔵合金をそのまま電極用合金粉末として使用した場
合、通常、初期の充放電において電極特性、すなわち初
期活性能が不充分である。そのため、あらかじめ水素吸
蔵合金の活性を高めるための処理を行うことが好まし
く、その処理方法に関しても多くの提案がなされてい
る。The negative electrode active material of a nickel-hydrogen storage battery generally has a CaCu 5 type crystal structure and has the formula: MmNi 5 (Mm is a mixture of rare earth elements, and a part of Ni is Co, Mn, Al. And an alloy represented by (substitute with Cu, etc.) are widely used. In addition, research and development of new hydrogen storage alloys are being actively conducted in order to realize further size reduction and weight reduction of batteries. When the produced hydrogen storage alloy is used as it is as an alloy powder for an electrode, the electrode characteristics, that is, the initial activation ability, are usually insufficient in the initial charge and discharge. Therefore, it is preferable to previously perform a treatment for increasing the activity of the hydrogen storage alloy, and many treatment methods have been proposed.
【０００５】このような水素吸蔵合金の活性を高める方
法としては、水素吸蔵合金の電気化学的活性を向上させ
るニッケルなどの成分を、物理的に水素吸蔵合金の表面
に付着させる方法、無電解メッキなどにより水素吸蔵合
金の表面をニッケルメッキする方法などが提案されてい
る。しかし、実用的な観点からは、水素吸蔵合金の表面
を化学的にエッチングしてその活性を高める方法が、比
較的安価である点で有望である。As a method of enhancing the activity of such a hydrogen storage alloy, a method of physically adhering a component such as nickel, which improves the electrochemical activity of the hydrogen storage alloy, to the surface of the hydrogen storage alloy, electroless plating. For example, a method of plating the surface of the hydrogen storage alloy with nickel has been proposed. However, from a practical point of view, a method of chemically etching the surface of the hydrogen storage alloy to increase its activity is promising because it is relatively inexpensive.
【０００６】水素吸蔵合金の表面を化学的にエッチング
してその活性を高める方法として、アルカリ水溶液に水
素吸蔵合金を浸漬する方法（例えば特開昭６１−２８５
６５８号および特願２０００−３９８９６４号各公
報）、酸水溶液に水素吸蔵合金を浸漬処理する方法、お
よびこれらを組み合わせた方法（例えば特開平９−７５
９１号および特開平９−１７１８２１号各公報）が提案
されている。これらの方法においては、水素吸蔵合金の
構成元素のうちアルカリ水溶液に対して不安定な元素が
水溶液中に溶出し、同時に水素吸蔵合金の表面にＮｉを
豊富に含んだ層が形成される。しかし、これらの方法を
用いても、得られる電池の初期出力特性はまだ充分であ
るとは言えず、より大幅な改善が求められている。As a method of chemically etching the surface of the hydrogen storage alloy to increase its activity, a method of immersing the hydrogen storage alloy in an alkaline aqueous solution (see, for example, JP-A-61-285).
No. 658 and Japanese Patent Application No. 2000-398964), a method of immersing a hydrogen storage alloy in an aqueous acid solution, and a method of combining these methods (for example, JP-A-9-75).
No. 91 and Japanese Unexamined Patent Publication No. 9-171821) have been proposed. In these methods, among the constituent elements of the hydrogen storage alloy, an element unstable to the alkaline aqueous solution is eluted into the aqueous solution, and at the same time, a Ni-rich layer is formed on the surface of the hydrogen storage alloy. However, even if these methods are used, the initial output characteristics of the obtained battery cannot be said to be sufficient, and more significant improvement is required.
【０００７】[0007]
【発明が解決しようとする課題】これに対し、一般的に
出力を高めるために比表面積を大きくする方法が知られ
ている。合金粉末の粒径を小さくすると単位重量当たり
の比表面積は大きくなって初期の出力は向上する。とこ
ろが、この場合、永続的に電解液に接する合金粉末の表
面積が大きいため、電解液への合金構成元素の溶出が早
く、寿命が短くなるといった問題が存在する。また、特
開平９−１７１８２１号公報に開示されている処理方法
によって、合金粉末の表面をエッチングして比表面積を
増加させることもできるが、基本的には処理前の水素吸
蔵合金の比表面積に依存しているため、限界がある。On the other hand, a method of increasing the specific surface area is generally known in order to increase the output. When the particle size of the alloy powder is reduced, the specific surface area per unit weight is increased and the initial output is improved. However, in this case, since the surface area of the alloy powder that is permanently in contact with the electrolytic solution is large, there is a problem that the alloy constituent elements elute into the electrolytic solution quickly and the life is shortened. Further, the surface area of the alloy powder can be etched to increase the specific surface area by the processing method disclosed in Japanese Patent Application Laid-Open No. 9-171821, but basically, the specific surface area of the hydrogen storage alloy before the processing can be increased. There is a limit because it depends.
【０００８】そこで、本発明は、上記問題を解決し、電
池に用いる際に初期から優れた電極活性を示し、サイク
ル寿命特性に優れたアルカリ蓄電池を実現し得る電極用
合金粉末、およびその製造方法を提供することを目的と
する。本発明の製造方法で得られた電極用合金粉末は、
初期高率放電特性およびサイクル特性に優れた電池を与
え得るものである。[0008] Therefore, the present invention solves the above problems, shows an excellent electrode activity from the beginning when used in a battery, and can realize an alkaline storage battery having excellent cycle life characteristics, and a method for producing the same. The purpose is to provide. The alloy powder for electrodes obtained by the production method of the present invention,
It is possible to provide a battery having excellent initial high rate discharge characteristics and cycle characteristics.
【０００９】[0009]
【課題を解決するための手段】本発明は、表面に無数の
くぼみを有することを特徴とする電極用水素吸蔵合金粉
末に関する。前記くぼみの平均直径は０．１μｍ以上２
μｍ以下であるのが有効である。本発明は、前記電極用
水素吸蔵合金粉末を使用した電池にも関する。SUMMARY OF THE INVENTION The present invention relates to a hydrogen storage alloy powder for an electrode, which has innumerable dents on its surface. The average diameter of the depressions is 0.1 μm or more 2
It is effective that it is less than or equal to μm. The present invention also relates to a battery using the hydrogen storage alloy powder for electrodes.
【００１０】また、本発明は、水素吸蔵合金粉末を過酸
化水素水および酸の混合溶液に投入することにより、前
記水素吸蔵合金粉末の表面にくぼみを形成する工程
（１）を含むことを特徴とする粒子状で表面にくぼみを
有する電極用水素吸蔵合金粉末の製造方法に関する。前
記製造方法は、さらに、前記工程（１）を経た前記水素
吸蔵合金粉末をアルカリ水溶液に浸漬して処理する工程
（２）および／または前記工程（１）を経た前記水素吸
蔵合金粉末を酸水溶液に浸漬して処理する工程（３）を
含むのが有効である。Further, the present invention comprises the step (1) of forming a depression on the surface of the hydrogen storage alloy powder by introducing the hydrogen storage alloy powder into a mixed solution of hydrogen peroxide solution and acid. The present invention relates to a method for producing a hydrogen storage alloy powder for an electrode, which is in the form of particles and has depressions on the surface. The manufacturing method further includes a step (2) of immersing the hydrogen storage alloy powder that has been subjected to the step (1) in an alkaline aqueous solution for treatment, and / or an acid aqueous solution of the hydrogen storage alloy powder that has been subjected to the step (1). It is effective to include the step (3) of immersing in and treating.
【００１１】[0011]
【発明の実施の形態】本発明は、表面に無数のくぼみを
有することにより比表面積の大きいことを特徴とする電
極用水素吸蔵合金粉末の製造方法、および当該水素吸蔵
合金粉末に関する。本発明者らは、電池に用いる際に初
期から優れた電極活性を示し、サイクル寿命特性に優れ
たアルカリ蓄電池を実現し得る電極用合金粉末を提供す
べく、鋭意検討した結果、従来技術にはない方法で比表
面積の大きい電極用水素吸蔵合金粉末が得られることを
見出した。BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a method for producing a hydrogen-absorbing alloy powder for electrodes, which has a large specific surface area by having innumerable depressions on the surface, and the hydrogen-absorbing alloy powder. The present inventors have shown an excellent electrode activity from the beginning when used in a battery, and as a result of diligent studies to provide an alloy powder for an electrode capable of realizing an alkaline storage battery having excellent cycle life characteristics, as a result of the conventional techniques, It was found that the hydrogen storage alloy powder for electrodes having a large specific surface area can be obtained by the non-existent method.
【００１２】本発明の電極用水素吸蔵合金粉末の平均粒
径は従来からのものと同様であればよく、特に限定はさ
れないが、小さすぎると寿命が低下し、大きすぎると出
力が小さくなるという理由から、１０〜５０μｍである
のが好ましく、さらに電極用の極板を作製する際の塗着
性を向上させ、かつ水素吸蔵合金の腐食を低減させると
いう理由から、１０〜３０μｍであるのが特に好まし
い。The average particle size of the hydrogen storage alloy powder for electrodes of the present invention is not particularly limited as long as it is the same as conventional ones, but if it is too small, the life is shortened, and if it is too large, the output is reduced. For the reason, it is preferably 10 to 50 μm, and further, it is 10 to 30 μm for the reason of improving the coating property when producing the electrode plate for the electrode and reducing the corrosion of the hydrogen storage alloy. Particularly preferred.
【００１３】また、本発明の水素吸蔵合金粉末は、その
表面に無数の微細なくぼみ（凹凸）ないしディンプルを
有することを特徴とする。換言すると、本発明の水素吸
蔵合金粉末の表面には、外部に開放した略半球状ないし
気泡状のくぼみが多数形成されている。Further, the hydrogen storage alloy powder of the present invention is characterized in that it has innumerable fine recesses (concavities and convexities) or dimples on its surface. In other words, on the surface of the hydrogen storage alloy powder of the present invention, a large number of substantially hemispherical or bubble-shaped depressions open to the outside are formed.
【００１４】このくぼみの平均直径は、有効に比表面積
を増大させるという理由から、また、製造上の制約か
ら、２μｍ以下であればよいが、その後のアルカリ処理
などによってくぼみが消滅しないように０．１μｍ以上
であるのが好ましい。The average diameter of the depressions may be 2 μm or less for the reason of effectively increasing the specific surface area and due to manufacturing restrictions. However, the depressions should have a diameter of 0 μm so as not to disappear due to subsequent alkali treatment. It is preferably at least 1 μm.
【００１５】また、水素吸蔵合金粉末の表面全体の面積
のうち、前記くぼみが存在する面積の割合としては、表
面積を有効に増やすという理由から、５０％以上であれ
ばよく、好ましくは８０％以上であるのが好ましい。加
えて、前記くぼみの深さは、有効に比表面積を増やし、
かつその後のアルカリ処理などによってくぼみが消滅し
ないように、０．０２μｍ以上であればよい。また、合
金の母相の減少を少なくするために、１μｍ以下である
のが好ましい。The ratio of the area where the depression is present to the total area of the surface of the hydrogen-absorbing alloy powder may be 50% or more, preferably 80% or more, for the reason of effectively increasing the surface area. Is preferred. In addition, the depth of the depression effectively increases the specific surface area,
In addition, the thickness may be 0.02 μm or more so that the dent does not disappear by the subsequent alkali treatment. Further, in order to reduce the decrease of the matrix phase of the alloy, it is preferably 1 μm or less.
【００１６】以上のような本発明に係る電極用水素吸蔵
合金粉末は、粒子状の水素吸蔵合金粉末を過酸化水素水
および酸の混合溶液に投入することにより、前記水素吸
蔵合金粉末の表面にくぼみを形成する工程（１）を含む
ことを特徴とする製造方法によって得ることができる。The hydrogen storage alloy powder for electrodes according to the present invention as described above is applied to the surface of the hydrogen storage alloy powder by introducing the particulate hydrogen storage alloy powder into a mixed solution of hydrogen peroxide solution and acid. It can be obtained by a manufacturing method characterized by including the step (1) of forming a depression.
【００１７】本発明において用いる水素吸蔵合金粉末と
しては、特に限定されるものではなく、種々のものを用
いることができる。したがって、本発明は、水素吸蔵合
金の組成に関わらず有効であると考えられる。The hydrogen storage alloy powder used in the present invention is not particularly limited, and various powders can be used. Therefore, the present invention is considered to be effective regardless of the composition of the hydrogen storage alloy.
【００１８】また、前記製造方法は、前記工程（１）の
前に、鋳造法によって作製された水素吸蔵合金を粉砕す
ることによって所定の粒径を有する水素吸蔵合金粉末を
得る前工程、またはガスアトマイズ法によって所定の粒
径を有する水素吸蔵合金粉末を得る前工程を含むのが好
ましい。これらの前工程により得られる粉末は比較的平
滑な表面を有する。In the manufacturing method, before the step (1), a hydrogen storage alloy powder having a predetermined particle size is obtained by pulverizing a hydrogen storage alloy produced by a casting method, or gas atomization. It is preferable to include a pre-process for obtaining a hydrogen storage alloy powder having a predetermined particle size by the method. The powder obtained by these previous steps has a relatively smooth surface.
【００１９】例えばＺｒ、ＮｉなどからなるＡＢ2型水
素吸蔵合金、Ｔｉ、Ｖ、Ｎｉなどからなるｂｃｃ型（体
心立方構造型）の水素吸蔵合金、Ｍｇ−Ｎｉ系の水素吸
蔵合金などを用いる場合においても本発明は有効であ
る。また、本発明は、水素吸蔵合金粉末を原料として用
いる限り、水素吸蔵合金の形状に関わらず有効である。
実際、後述する実施例における通常の粉砕により得られ
る粉末のみならず、アトマイズ法によって作製された球
（粒子）状に近い粉末の場合にも非常に有効である。For example, an AB 2 type hydrogen storage alloy made of Zr, Ni, etc., a bcc type (body-centered cubic structure type) hydrogen storage alloy made of Ti, V, Ni, etc., a Mg--Ni type hydrogen storage alloy, etc. are used. The present invention is effective even in such cases. Further, the present invention is effective regardless of the shape of the hydrogen storage alloy as long as the hydrogen storage alloy powder is used as a raw material.
In fact, it is very effective not only for powders obtained by ordinary pulverization in the examples described later, but also for powders close to spherical (particle) shape produced by the atomizing method.
【００２０】本発明の方法の工程（１）において用いる
混合溶液は、過酸化水素水と酸を含む。この酸として
は、例えば硫酸、硝酸および塩酸などがあげられる。ま
た、前記混合溶液中の過酸化水素水の割合としては、
０．５〜５重量％であればよく、１〜３重量％であるの
が好ましい。また、前記混合溶液中の酸の割合として
は、２〜２０重量％であればよく、５〜１５重量％であ
るのが好ましい。The mixed solution used in step (1) of the method of the present invention contains aqueous hydrogen peroxide and an acid. Examples of the acid include sulfuric acid, nitric acid and hydrochloric acid. Further, as the ratio of hydrogen peroxide water in the mixed solution,
It may be 0.5 to 5% by weight, preferably 1 to 3% by weight. The proportion of the acid in the mixed solution may be 2 to 20% by weight, preferably 5 to 15% by weight.
【００２１】前記混合溶液に比較的平滑な表面を有する
前記水素吸蔵合金粉末を投入して攪拌すると、表面にく
ぼみが形成され、その比表面積を例えば２〜４倍に増大
させることも可能である。このときの浸漬の条件として
は、１０〜６０℃で３〜６０秒間であることが好まし
い。When the hydrogen storage alloy powder having a relatively smooth surface is added to the mixed solution and stirred, a dent is formed on the surface, and the specific surface area can be increased to 2 to 4 times, for example. . The conditions for immersion at this time are preferably 10 to 60 ° C. and 3 to 60 seconds.
【００２２】さらに、本発明の方法は、前記水素吸蔵合
金粉末をアルカリ水溶液に浸漬して処理する工程（２）
および／または前記水素吸蔵合金粉末を酸水溶液に浸漬
して処理する工程（３）を含むのが好ましい。工程
（２）は、水素吸蔵合金粉末の表面に磁性体を形成させ
るために行うものであり、アルカリ水溶液としては、例
えば水酸化ナトリウム水溶液または水酸化カリウム水溶
液などを用いることができる。Further, in the method of the present invention, a step (2) of treating the hydrogen storage alloy powder by immersing it in an alkaline aqueous solution.
It is preferable to include a step (3) of treating the hydrogen-absorbing alloy powder by immersing it in an aqueous acid solution. The step (2) is carried out to form a magnetic substance on the surface of the hydrogen storage alloy powder, and as the alkaline aqueous solution, for example, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution can be used.
【００２３】水素吸蔵合金自体は磁性体ではないが、水
素吸蔵合金をアルカリ水溶液に浸漬すると、触媒活性の
高い金属状態のニッケルからなる微細な磁性体が、水素
吸蔵合金粉末を被覆するような状態で形成される。金属
状態のニッケルからなる磁性体とは、アルカリ処理によ
って生成した金属状態のニッケルを主成分とする強磁性
を示す物質を意味する。Although the hydrogen storage alloy itself is not a magnetic substance, when the hydrogen storage alloy is immersed in an alkaline aqueous solution, a fine magnetic substance made of nickel in a metallic state having high catalytic activity covers the hydrogen storage alloy powder. Is formed by. The magnetic substance made of nickel in a metallic state means a substance which is produced by alkali treatment and has a ferromagnetism containing nickel in a metallic state as a main component.
【００２４】金属状態のニッケルからなる磁性体の水素
吸蔵合金内における含有量は、例えば１０ｋＯｅの磁場
において合金粉末の飽和磁化を求め、その飽和磁化がす
べて金属状態のニッケルに基づいていると仮定したとき
に導かれる金属状態のニッケル量で表される。Regarding the content of the magnetic substance made of nickel in the metallic state in the hydrogen storage alloy, the saturation magnetization of the alloy powder was obtained in a magnetic field of, for example, 10 kOe, and it was assumed that the saturation magnetization was all based on nickel in the metallic state. It is sometimes expressed by the amount of nickel in the metallic state.
【００２５】前記工程（２）のアルカリ処理では、強磁
性を示す金属状態のコバルトなども生成するため、上記
方法で得られた金属状態のニッケルからなる磁性体の含
有量は、金属状態のニッケル量と金属状態のコバルトな
どの量の合計となる。本発明においては、金属状態のニ
ッケルからなる磁性体のことを、単に磁性体という。In the alkali treatment of the step (2), cobalt in a metallic state exhibiting ferromagnetism is also produced. Therefore, the content of the magnetic substance made of nickel in a metallic state obtained by the above method is in the state of nickel in a metallic state. It is the total of the amount and the amount of cobalt in the metallic state. In the present invention, a magnetic body made of nickel in a metallic state is simply referred to as a magnetic body.
【００２６】前記工程（２）では、例えば６０℃〜沸騰
温度の水酸化ナトリウムまたは水酸化カリウムの２０〜
６０重量％水溶液に、前記工程（１）を経た合金粉末を
攪拌しながら投入し、２０分間〜３時間浸漬処理をす
る。その後、前記合金粉末を温水で水洗し、上澄みを廃
棄する作業を繰り返す。In the step (2), for example, 20 to 20% of sodium hydroxide or potassium hydroxide having a boiling temperature of 60 ° C is used.
The alloy powder subjected to the above step (1) is put into a 60% by weight aqueous solution with stirring, and a dipping treatment is performed for 20 minutes to 3 hours. Then, the operation of washing the alloy powder with warm water and discarding the supernatant is repeated.
【００２７】また、前記工程（３）は、水素吸蔵合金粉
末の表面に磁性体を形成させるために行うものであり、
酸水溶液としては、例えば酢酸水溶液などを用いること
ができる。The step (3) is performed to form a magnetic substance on the surface of the hydrogen storage alloy powder,
As the acid aqueous solution, for example, acetic acid aqueous solution can be used.
【００２８】前記工程（３）においては、例えば３０〜
８０℃の酢酸水溶液に、前記工程（１）または（２）を
経た前記合金粉末を攪拌しながら投入し、１０分間〜１
時間浸漬処理をする。その後、前記合金粉末を水洗し、
上澄みを廃棄する作業を繰り返す。In the step (3), for example, 30 to
The alloy powder that has been subjected to the step (1) or (2) is put into an acetic acid aqueous solution at 80 ° C. with stirring, and for 10 minutes to 1
Immerse for time. Then, the alloy powder is washed with water,
Repeat the process of discarding the supernatant.
【００２９】また、工程（２）および工程（３）を両方
とも行う場合の順序は、前記工程（２）の後に前記工程
（３）を行うのが好ましい。これは、工程（２）で形成
された表面酸化物を工程（３）で除去することが可能だ
からである。つぎに、実施例に基づいて本発明を具体的
に説明するが、本発明はこれらのみに限定されるもので
はない。The order of performing both step (2) and step (3) is preferably such that step (3) is performed after step (2). This is because the surface oxide formed in step (2) can be removed in step (3). Next, the present invention will be specifically described based on Examples, but the present invention is not limited thereto.
【００３０】[0030]
【実施例】《実施例１》アルカリ処理
前工程
Ｍｍ、Ｎｉ、Ｍｎ、ＡｌおよびＣｏを所定の割合で混合
し、高周波溶解炉で組成がＭｍＮｉ4.1Ｍｎ0.4Ａｌ0.3
Ｃｏ0.4の水素吸蔵合金のインゴットを作製した。この
インゴットをアルゴン雰囲気下、１０６０℃で１０時間
加熱処理した後、粗粒子に粉砕し、湿式ボールミルを用
いて水の存在下で７５μｍ以下に粉砕して平均粒径２４
μｍの水素吸蔵合金粉末ａを得て、これを乾燥した（従
来例：従来の水素吸蔵合金粉末）。EXAMPLES Example 1 Alkali Treatment Pre-Process Mm, Ni, Mn, Al and Co are mixed in a predetermined ratio and the composition is MmNi 4.1 Mn 0.4 Al 0.3 in a high frequency melting furnace.
A Co 0.4 hydrogen storage alloy ingot was prepared. This ingot was heat-treated at 1060 ° C. for 10 hours in an argon atmosphere, then crushed into coarse particles, and crushed to 75 μm or less in the presence of water using a wet ball mill to obtain an average particle size of 24.
A hydrogen storage alloy powder a of μm was obtained and dried (conventional example: conventional hydrogen storage alloy powder).
【００３１】工程（１）
つぎに、前記水素吸蔵合金粉末ａを１０重量％の硫酸と
２重量％の過酸化水素水の混合水溶液（室温）に攪拌し
ながら投入した。気泡が発生した後、吸引濾過および水
洗を行った。なお、合金投入後、吸引濾過するまでは約
１０秒程度であった。この浸漬処理を経た水素吸蔵合金
粉末ｂの一部を乾燥した。Step (1) Next, the hydrogen storage alloy powder a was put into a mixed aqueous solution (room temperature) of 10 wt% sulfuric acid and 2 wt% hydrogen peroxide water while stirring. After bubbles were generated, suction filtration and washing with water were performed. It was about 10 seconds after the alloy was charged and before suction filtration. A part of the hydrogen storage alloy powder b that had been subjected to this immersion treatment was dried.
【００３２】工程（２）
一方、前記工程（１）で得た水素吸蔵合金粉末ｂの一部
を湿った状態のまま、４４重量％ＮａＯＨ水溶液中に浸
漬し、１１５℃で１時間攪拌した。ついで、温水中に浸
漬し、攪拌しながらの水洗および上澄みの廃棄作業を繰
り返し、乾燥して本発明の水素吸蔵合金粉末Ｂを得た。Step (2) On the other hand, a part of the hydrogen storage alloy powder b obtained in the above step (1) was immersed in a 44 wt% NaOH aqueous solution in a wet state and stirred at 115 ° C. for 1 hour. Then, the hydrogen storage alloy powder B of the present invention was obtained by immersing in warm water, repeating washing with stirring and discarding the supernatant, and drying.
【００３３】《比較例１》工程（１）を行わないこと以
外は実施例１と同様にして比較用水素吸蔵合金粉末Ｑを
得た。Comparative Example 1 Comparative hydrogen storage alloy powder Q was obtained in the same manner as in Example 1 except that step (1) was not performed.
【００３４】《比較例２》４４重量％ＮａＯＨ水溶液中
で１１５℃で３時間攪拌しながら浸漬処理を行ったこと
以外は、比較例１と同様にして温水で攪拌しながら水洗
し、上澄みを廃棄する作業を繰り返し比較用水素吸蔵合
金粉末Ｒを得た。<Comparative Example 2> Washing with stirring with warm water was carried out in the same manner as in Comparative Example 1 except that immersion treatment was carried out in a 44% by weight NaOH aqueous solution at 115 ° C. for 3 hours while stirring, and the supernatant was discarded. The above operation was repeated to obtain a hydrogen storage alloy powder R for comparison.
【００３５】《実施例２》アルカリ＋酢酸処理
工程（２）および工程（３）を以下のように行ったこと
以外は、実施例１と同様にして本発明の水素吸蔵合金粉
末Ｃを得た。実施例１の工程（１）を経た水素吸蔵合金
粉末ｂを湿った状態のまま、３１重量％ＫＯＨ水溶液中
に浸漬し、１００℃で１時間攪拌した（工程（２））。
つぎに、この工程（２）を経た水素吸蔵合金粉末ｂを温
水中に浸漬して攪拌しながら水洗し、上澄みを廃棄する
作業を繰り返した。さらに、前記水素吸蔵合金粉末ｂを
０．１Ｍ、６０℃の酢酸水溶液に３０分間浸漬した後
（工程（３））、２重量％の過酸化水素水を攪拌しなが
ら投入し、その後水洗、乾燥することで本発明の水素吸
蔵合金粉末Ｃを得た。Example 2 Alkali + Acetic Acid Treatment A hydrogen storage alloy powder C of the present invention was obtained in the same manner as in Example 1 except that the steps (2) and (3) were carried out as follows. . The hydrogen storage alloy powder b obtained through the step (1) of Example 1 was dipped in a 31 wt% KOH aqueous solution in a wet state and stirred at 100 ° C. for 1 hour (step (2)).
Next, the hydrogen-absorbing alloy powder b having undergone this step (2) was immersed in warm water, washed with water with stirring, and the supernatant was discarded. Further, the hydrogen-absorbing alloy powder b was immersed in an acetic acid aqueous solution of 0.1 M at 60 ° C. for 30 minutes (step (3)), 2% by weight of hydrogen peroxide was added while stirring, and then washed with water and dried. By doing so, the hydrogen storage alloy powder C of the present invention was obtained.
【００３６】《比較例３》工程（１）を行わないこと以
外は、実施例２と同様にして比較用水素吸蔵合金粉末Ｓ
を得た。Comparative Example 3 Comparative hydrogen storage alloy powder S was prepared in the same manner as in Example 2 except that the step (1) was not carried out.
Got
【００３７】《比較例４》小粒径の場合
湿式ボールミルを用いて水の存在下で実施例１よりも粉
砕条件をきつくすることで、平均粒径８μｍの水素吸蔵
合金粉末ｔを得た。工程（１）を行わず、この水素吸蔵
合金粉末ｔを湿った状態のまま、４４重量％ＮａＯＨ水
溶液に浸漬し、１１５℃で１時間攪拌した（工程
（２））。つぎに、前記工程（２）を経た水素吸蔵合金
粉末ｔを温水中に浸漬して攪拌しながら水洗および加圧
脱水を繰り返し、乾燥して比較用水素吸蔵合金粉末Ｔを
得た。Comparative Example 4 Small Particle Size A hydrogen-absorbing alloy powder t having an average particle size of 8 μm was obtained by using a wet ball mill in the presence of water under more severe grinding conditions than in Example 1. Without carrying out step (1), the hydrogen storage alloy powder t was dipped in a 44 wt% NaOH aqueous solution in a wet state and stirred at 115 ° C. for 1 hour (step (2)). Next, the hydrogen storage alloy powder t subjected to the step (2) was immersed in warm water, washed repeatedly with stirring and dehydration under pressure, and dried to obtain a hydrogen storage alloy powder T for comparison.
【００３８】［評価］
表面構造
所定の処理を行わない比較用水素吸蔵合金粉末ａと、本
発明の製造方法により得られた水素吸蔵合金粉末ｂのＳ
ＥＭ写真を、それぞれ図１の（１）と、（２）および
（３）に示す。なお、図１の（２）および（３）は、そ
れぞれ本発明の水素吸蔵合金粉末ｂを異なる位置で撮影
したＳＥＭ写真である。図１の（２）および（３）から
わかるように、本発明の水素吸蔵合金粉末ｂの表面には
無数のくぼみができていることがわかる。[Evaluation] Surface structure S of comparative hydrogen storage alloy powder a not subjected to a predetermined treatment and hydrogen storage alloy powder b obtained by the production method of the present invention.
The EM photographs are shown in (1), (2) and (3) of FIG. 1, respectively. 1 (2) and (3) are SEM photographs of the hydrogen storage alloy powder b of the present invention taken at different positions. As can be seen from (2) and (3) in FIG. 1, innumerable dents are formed on the surface of the hydrogen storage alloy powder b of the present invention.
【００３９】粒度分布および比表面積
つぎに、本発明の水素吸蔵合金粉末ｂおよび比較用水素
吸蔵合金粉末ａの粒度分布と比表面積を測定したとこ
ろ、平均粒径はともにほぼ同じであるにもかかわらず、
本発明の水素吸蔵合金粉末ｂの比表面積は比較用水素吸
蔵合金粉末ａの比表面積の３倍であった。測定値を表１
に示した。また、水素吸蔵合金粉末ｔの比表面積も比較
用水素吸蔵合金粉末ａの比表面積の３倍であった。Particle Size Distribution and Specific Surface Area Next, the particle size distribution and specific surface area of the hydrogen storage alloy powder b of the present invention and the comparative hydrogen storage alloy powder a were measured, and the average particle diameters were almost the same. No
The specific surface area of the hydrogen storage alloy powder b of the present invention was 3 times the specific surface area of the comparative hydrogen storage alloy powder a. Table 1 shows the measured values
It was shown to. Further, the specific surface area of the hydrogen storage alloy powder t was 3 times the specific surface area of the comparative hydrogen storage alloy powder a.
【００４０】[0040]
【表１】 [Table 1]
【００４１】このように、本発明の方法によって、表面
にくぼみを有することで通常の粉砕により得られる水素
吸蔵合金粉末に比べて比表面積の大きな水素吸蔵合金粉
末が得られることがわかる。なお、粒度分布および平均
粒径は、（株）島津製作所製の湿式レーザー回折粒度分
布計ＳＡＬＤ−１０００を用いて測定し、比表面積はＫ
ｒによるＢＥＴ法で測定した。As described above, it is understood that the method of the present invention makes it possible to obtain a hydrogen storage alloy powder having a specific surface area which is larger than that of a hydrogen storage alloy powder obtained by ordinary pulverization because it has a depression. The particle size distribution and average particle size are measured using a wet laser diffraction particle size distribution analyzer SALD-1000 manufactured by Shimadzu Corporation, and the specific surface area is K.
It was measured by the BET method by r.
【００４２】磁化率
本発明の水素吸蔵合金粉末ＢおよびＣでは、それぞれ同
様の処理を施した比較用水素吸蔵合金粉末ＱおよびＳに
比べて、約３倍の磁性体を含んでいた。これは、比表面
積の増加に対応していると考えられ、粒径を小さくする
ことで比表面積を増加させた比較用水素吸蔵合金粉末Ｔ
においても、同様に比表面積にほぼ応じた磁性体量の増
加が観測された。Magnetic Susceptibility The hydrogen storage alloy powders B and C of the present invention contained about 3 times as much magnetic material as the comparative hydrogen storage alloy powders Q and S which were respectively subjected to the same treatment. This is considered to correspond to the increase in the specific surface area, and the hydrogen storage alloy powder T for comparison having the specific surface area increased by decreasing the particle size is used.
In the same manner, an increase in the amount of the magnetic material was also observed in almost the same manner as in the specific surface area.
【００４３】電極特性
つぎに、密閉式ニッケル水素蓄電池を作製し、電極特性
を評価した。上述のようにして得た本発明の水素吸蔵合
金粉末ＢおよびＣ、ならびに比較用水素吸蔵合金粉末Ｑ
〜Ｔのいずれか１００重量部に対して、カルボキシメチ
ルセルロース０．１５重量部、カーボンブラック０．３
重量部およびスチレンブタジエン共重合体０．７重量部
を加えて混合物を得、さらにこの混合物に水を添加して
混練してペーストを得た。このペーストをパンチングメ
タルに塗着し、乾燥後、ロールプレスして所定の厚さに
し、所定の大きさに切断して、負極とした。Electrode Characteristics Next, a sealed nickel-hydrogen storage battery was prepared and the electrode characteristics were evaluated. The hydrogen storage alloy powders B and C of the present invention obtained as described above, and the hydrogen storage alloy powder Q for comparison
To T for 100 parts by weight, 0.15 parts by weight of carboxymethyl cellulose and 0.3 parts of carbon black
By weight, 0.7 part by weight of a styrene-butadiene copolymer was added to obtain a mixture, and water was further added to the mixture and kneaded to obtain a paste. This paste was applied to a punching metal, dried, and then roll pressed to a predetermined thickness and cut into a predetermined size to obtain a negative electrode.
【００４４】得られた負極と公知の発泡状芯材を有する
ニッケル正極とを、スルホン酸基を導入したポリプロピ
レン製不織布のセパレータを介して積層し、巻回して、
円筒状の電極群を得た。この電極群を金属ケースに挿入
し、ついで、ＫＯＨを主成分とする比重１．３０ｇ／ｃ
ｃのアルカリ水溶液を電解液として金属ケースに注入
し、金属ケースを封口した。このようにして公知のｓｕ
ｂ−Ｃサイズの密閉式ニッケル水素蓄電池を得た。電池
の容量は約３Ａｈであった。The obtained negative electrode and a known nickel positive electrode having a foamed core material were laminated with a separator made of a polypropylene non-woven fabric into which a sulfonic acid group had been introduced, and wound,
A cylindrical electrode group was obtained. This electrode group was inserted into a metal case, and then the specific gravity of KOH as a main component was 1.30 g / c.
The alkaline aqueous solution of c was injected as an electrolytic solution into the metal case, and the metal case was sealed. In this way, the known su
A bC size sealed nickel-metal hydride storage battery was obtained. The capacity of the battery was about 3 Ah.
【００４５】（ｉ）初期低温高率放電特性
得られた電池を２５℃、１０時間率で１５時間充電し、
５時間率で電池電圧が１Ｖになるまで放電するサイクル
を３回行い、３回目の放電容量をＣ１とした。つぎに、
電池を２５℃、１０時間率で１５時間充電し、０℃にし
た後、６Ａで電池電圧が０．６Ｖになるまで放電した。
このときの放電容量をＣ２とし、容量比率を式：
（高率放電特性）＝（Ｃ２／Ｃ１）×１００
にしたがって求めた。結果を表２に示した。(I) Initial low temperature high rate discharge characteristics The obtained battery is charged at 25 ° C. for 10 hours at a rate of 15 hours,
The cycle of discharging the battery voltage to 1 V at a rate of 5 hours was repeated three times, and the discharge capacity at the third time was defined as C1. Next,
The battery was charged at 25 ° C. for 10 hours at a rate of 10 hours, brought to 0 ° C., and then discharged at 6 A until the battery voltage reached 0.6 V.
The discharge capacity at this time was defined as C2, and the capacity ratio was determined according to the formula: (High rate discharge characteristics) = (C2 / C1) × 100. The results are shown in Table 2.
【００４６】（ｉｉ）サイクル寿命
得られた電池を、４５℃環境下において、１時間率で４
０分充電し、１時間率で電池電圧が１Ｖになるまで放電
するサイクルを繰り返し行い、サイクル寿命を測定し
た。２０サイクルごとに２５℃、１０時間率で１５時間
充電し、５時間率で電池電圧が１Ｖになるまで放電する
サイクルを行い。放電容量がＣ１の６０％を切るまでの
サイクル数を、サイクル寿命として表２に示した。(Ii) Cycle life The obtained battery was subjected to 4 hours at an hour rate in an environment of 45 ° C.
The cycle of charging for 0 minutes and discharging at a rate of 1 hour until the battery voltage became 1 V was repeated to measure the cycle life. Every 20 cycles, the battery was charged at 25 ° C. for 10 hours at a rate of 15 hours and discharged at a rate of 5 hours until the battery voltage became 1 V. The number of cycles until the discharge capacity falls below 60% of C1 is shown in Table 2 as cycle life.
【００４７】[0047]
【表２】 [Table 2]
【００４８】まず、本発明の水素吸蔵合金粉末Ｂを用い
た電池と、比較用水素吸蔵合金粉末Ｑを用いた電池とを
比較する。本発明の水素吸蔵合金粉末Ｂを用いた電池
は、初期低温高率放電特性に非常に優れていることがわ
かる。これは表面のＮｉ触媒量に依存していると考えら
れる。同様の傾向は、本発明の水素吸蔵合金粉末Ｃと比
較用水素吸蔵合金粉末Ｓの間にも認められる。First, a battery using the hydrogen storage alloy powder B of the present invention and a battery using the comparative hydrogen storage alloy powder Q will be compared. It can be seen that the battery using the hydrogen storage alloy powder B of the present invention is very excellent in initial low temperature high rate discharge characteristics. It is considered that this depends on the amount of Ni catalyst on the surface. A similar tendency is observed between the hydrogen storage alloy powder C of the present invention and the comparative hydrogen storage alloy powder S.
【００４９】ここで、磁性体量の等しい本発明の水素吸
蔵合金粉末Ｂおよび比較用水素吸蔵合金粉末Ｒを用いた
電池を比較してみる。触媒Ｎｉ量が等しいにもかかわら
ず、比較用水素吸蔵合金粉末Ｒを用いた電池は低温での
高率放電特性が大きく劣っている。これは、比表面積が
本発明の水素吸蔵合金粉末Ｂより比較用水素吸蔵合金粉
末Ｒの方が小さいため、同じ磁性体量をもつということ
は、表面からより深いところまで処理がなされたことを
意味している。これらの触媒層はある深さまでは触媒と
して働くが、厚みが増しすぎるとすべての触媒が反応に
関与せず、逆に反応阻害層として作用していると考えら
れるため、こうした結果になったと考えられる。Here, the batteries using the hydrogen storage alloy powder B of the present invention and the hydrogen storage alloy powder R for comparison having the same magnetic substance amount will be compared. Despite the same amount of catalyst Ni, the battery using the comparative hydrogen storage alloy powder R is greatly inferior in high rate discharge characteristics at low temperature. This is because the comparative hydrogen storage alloy powder R has a specific surface area smaller than that of the hydrogen storage alloy powder B of the present invention, and thus having the same magnetic substance amount means that the treatment was performed from the surface to a deeper position. I mean. These catalyst layers act as catalysts up to a certain depth, but when the thickness is too thick, not all catalysts participate in the reaction, but it is thought that they act as reaction inhibition layers on the contrary. To be
【００５０】つぎに本発明の水素吸蔵合金粉末Ｂを用い
た電池と、当該粉末Ｂと同じ比表面積を持つ比較用水素
吸蔵合金粉末Ｔを用いた電池とを比較した。この２つの
合金は、磁性体量と比表面積がほぼ等しいため、触媒層
の厚みはほぼ等しいと考えられる。実際、初期の低温出
力特性は、比較用水素吸蔵合金粉末Ｔを用いた電池でも
比較的良い値となっている。本発明の水素吸蔵合金粉末
Ｂを用いた電池に対して多少劣っている理由は、合金粉
末が小さいため合金同士の接触点が増加し、接触抵抗が
増加したためと考えられる。Next, a battery using the hydrogen storage alloy powder B of the present invention was compared with a battery using the comparative hydrogen storage alloy powder T having the same specific surface area as the powder B. Since the two alloys have almost the same amount of magnetic material and specific surface area, it is considered that the catalyst layers have almost the same thickness. In fact, the initial low-temperature output characteristic is a relatively good value even in the battery using the comparative hydrogen storage alloy powder T. It is considered that the reason why the battery using the hydrogen storage alloy powder B of the present invention is slightly inferior is that the contact points between the alloys are increased and the contact resistance is increased because the alloy powder is small.
【００５１】ここで、この２つのサイクル寿命特性を比
較したところ、非常に大きな違いが観測された。この違
いは、比較用水素吸蔵合金粉末Ｔが本発明の水素吸蔵合
金粉末Ｂに比べて電解液中の腐食速度が速い結果と考え
られる。比較用水素吸蔵合金粉末Ｔがほぼ初期の比表面
積に対応した腐食速度で最後まで合金が溶解するのに対
し、本発明のくぼみを持つことで比表面積が大きな合金
は、初期こそ比表面積に対応した腐食速度を示すが、徐
々に腐食面と合金表面の境界の面積は、くぼみを持たな
い通常の粉砕によるものに近くなることで、腐食に作用
する比表面積が減少し、腐食量が減少してくるためであ
ると考えられる。Here, when these two cycle life characteristics were compared, a very large difference was observed. It is considered that this difference is because the hydrogen storage alloy powder T for comparison has a higher corrosion rate in the electrolytic solution than the hydrogen storage alloy powder B of the present invention. While the comparative hydrogen-absorbing alloy powder T melts to the end at a corrosion rate corresponding to the initial specific surface area, the alloy having a large specific surface area due to the depression of the present invention corresponds to the specific surface area at the initial stage. The area of the boundary between the corrosion surface and the alloy surface gradually becomes closer to that of normal crushing without pits, which reduces the specific surface area that acts on corrosion and reduces the amount of corrosion. It is thought to be for coming.
【００５２】以上のように、本発明により、アルカリ電
解液中で腐食されにくく、初期の充放電サイクルにおい
ても優れた電極活性を示し、初期の低温高率放電特性お
よびサイクル寿命に優れたアルカリ蓄電池を与え得る電
極用合金粉末を得ることができる。As described above, according to the present invention, an alkaline storage battery which is not easily corroded in an alkaline electrolyte, exhibits excellent electrode activity even in the initial charge / discharge cycle, and has excellent initial low temperature high rate discharge characteristics and cycle life. It is possible to obtain an alloy powder for an electrode that can give
【００５３】[0053]
【発明の効果】本発明によれば、初期の充放電サイクル
においても優れた電極活性を示し、高率放電特性および
サイクル寿命に優れたアルカリ蓄電池を与え得る電極用
合金粉末を得ることができる。EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain an alloy powder for an electrode which exhibits excellent electrode activity even in the initial charge / discharge cycle, and which can provide an alkaline storage battery excellent in high rate discharge characteristics and cycle life.
【図１】本発明により得られた水素吸蔵合金粉末の表面
状態と、通常の水素吸蔵合金粉末の表面状態を示すＳＥ
Ｍ写真である。FIG. 1 SE showing the surface state of a hydrogen storage alloy powder obtained by the present invention and the surface state of a normal hydrogen storage alloy powder.
It is an M photograph.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 辻 庸一郎 大阪府門真市大字門真1006番地 松下電器 産業株式会社内 Ｆターム(参考） 4K018 AA07 BA04 BA08 BC01 BC08 BC09 BD07 FA14 HA10 KA38 5H028 AA02 BB03 HH05 5H050 AA02 AA07 BA14 CA03 CB16 CB17 CB18 FA17 GA12 GA14 GA25 HA04 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor, Yoichiro Tsuji 1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric Sangyo Co., Ltd. F-term (reference) 4K018 AA07 BA04 BA08 BC01 BC08 BC09 BD07 FA14 HA10 KA38 5H028 AA02 BB03 HH05 5H050 AA02 AA07 BA14 CA03 CB16 CB17 CB18 FA17 GA12 GA14 GA25 HA04
Claims (5)
とする電極用水素吸蔵合金粉末。1. A hydrogen storage alloy powder for an electrode, which has innumerable dents on its surface.
２μｍ以下であることを特徴とする請求項１記載の電極
用水素吸蔵合金粉末。2. The hydrogen storage alloy powder for an electrode according to claim 1, wherein the recesses have an average diameter of 0.1 μm or more and 2 μm or less.
酸の混合溶液に投入することにより、前記水素吸蔵合金
粉末の表面にくぼみを形成する工程（１）を含むことを
特徴とする粒子状で表面にくぼみを有する電極用水素吸
蔵合金粉末の製造方法。3. A particulate form comprising a step (1) of forming a depression on the surface of the hydrogen storage alloy powder by introducing the hydrogen storage alloy powder into a mixed solution of hydrogen peroxide solution and an acid. A method for producing a hydrogen storage alloy powder for an electrode, the surface of which has a hollow.
吸蔵合金粉末をアルカリ水溶液に浸漬して処理する工程
（２）および／または前記工程（１）を経た前記水素吸
蔵合金粉末を酸水溶液に浸漬して処理する工程（３）を
含むことを特徴とする請求項３記載の電極用水素吸蔵合
金粉末の製造方法。4. The step (2) of immersing the hydrogen storage alloy powder that has undergone the step (1) in an alkaline aqueous solution for treatment, and / or the hydrogen storage alloy powder that has passed the step (1) in an acid aqueous solution. The method for producing a hydrogen storage alloy powder for an electrode according to claim 3, further comprising a step (3) of immersing in hydrogen and treating.
極用水素吸蔵合金粉末を用いた電池。5. A battery using the hydrogen storage alloy powder for an electrode, which has a depression on the surface according to claim 1.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001370468A JP2003173772A (en) | 2001-12-04 | 2001-12-04 | Hydrogen storage alloy powder for electrode and its manufacturing method |
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| Country | Link |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005279418A (en) * | 2004-03-29 | 2005-10-13 | Taiheiyo Cement Corp | Apparatus and process for producing hydrogen storage material, and hydrogen storage material |
| CN100438148C (en) * | 2005-09-21 | 2008-11-26 | 比亚迪股份有限公司 | Alloy powder surface treatment method |
| JP2009287044A (en) * | 2008-05-27 | 2009-12-10 | Mitsui Mining & Smelting Co Ltd | Metal particulate, and method for producing metal particulate |
-
2001
- 2001-12-04 JP JP2001370468A patent/JP2003173772A/en not_active Withdrawn
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005279418A (en) * | 2004-03-29 | 2005-10-13 | Taiheiyo Cement Corp | Apparatus and process for producing hydrogen storage material, and hydrogen storage material |
| JP4703126B2 (en) * | 2004-03-29 | 2011-06-15 | 太平洋セメント株式会社 | Hydrogen storage material manufacturing apparatus and hydrogen storage material manufacturing method |
| CN100438148C (en) * | 2005-09-21 | 2008-11-26 | 比亚迪股份有限公司 | Alloy powder surface treatment method |
| JP2009287044A (en) * | 2008-05-27 | 2009-12-10 | Mitsui Mining & Smelting Co Ltd | Metal particulate, and method for producing metal particulate |
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