JPH09213317A - Manufacture of hydrogen storage alloy electrode - Google Patents
Manufacture of hydrogen storage alloy electrodeInfo
- Publication number
- JPH09213317A JPH09213317A JP8040583A JP4058396A JPH09213317A JP H09213317 A JPH09213317 A JP H09213317A JP 8040583 A JP8040583 A JP 8040583A JP 4058396 A JP4058396 A JP 4058396A JP H09213317 A JPH09213317 A JP H09213317A
- Authority
- JP
- Japan
- Prior art keywords
- alloy
- hydrogen
- hydrogen storage
- storage alloy
- alkaline solution
- 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.)
- Pending
Links
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
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、水素吸蔵合金を電
極として用いた水素吸蔵合金電極の製造方法に関するも
のである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hydrogen storage alloy electrode using a hydrogen storage alloy as an electrode.
【０００２】[0002]
【従来の技術】水素吸蔵合金は、その水素の吸収・放出
反応を利用して各種用途に応用されており、その応用例
の一つとして電池用の電極として使用されている。とこ
ろで、最近では携帯用コンピュータや携帯電話などが益
々普及し、これに伴い、高容量二次電池の需要が増して
いる。水素吸蔵合金電極を負極として用いたニッケル・
水素二次電池は、現在広く用いられているニッケル・カ
ドミウム電池と作動電圧で互換性があり、しかも高容量
を示すため、多くの用途で商品化されている。現在商品
化されているニッケル・水素二次電池用の水素吸蔵合金
は主にＭｍ（ミッシュメタル）Ｎｉ5系の合金である。
しかし、この合金系は比較的放電容量が小さいこと、電
池電極としての寿命が不十分であることなどの問題点を
有している。そこでこのニッケル・水素二次電池をさら
に高容量・長寿命なものとするため、この条件を満たす
と思われるＡＢ2型ラーベス相構造を有する合金の開発
が精力的に行われている。2. Description of the Related Art Hydrogen storage alloys are used in various applications by utilizing their hydrogen absorption / desorption reactions, and as one of the application examples, they are used as electrodes for batteries. By the way, recently, portable computers, mobile phones, and the like have become more and more popular, and accordingly, the demand for high-capacity secondary batteries is increasing. Nickel using hydrogen storage alloy electrode as negative electrode
The hydrogen secondary battery is compatible with the nickel-cadmium battery which is widely used at present in operating voltage and has a high capacity, and therefore has been commercialized in many applications. The hydrogen storage alloys currently commercialized for nickel-hydrogen secondary batteries are mainly Mm (Misch metal) Ni 5 type alloys.
However, this alloy system has problems such as a relatively small discharge capacity and an insufficient life as a battery electrode. Therefore, in order to make this nickel-hydrogen secondary battery have a higher capacity and a longer life, an alloy having an AB 2 type Laves phase structure that is considered to satisfy this condition is being vigorously developed.
【０００３】[0003]
【発明が解決しようとする課題】しかし、ＡＢ2型ラー
ベス相構造を有する合金を電極として用いると確かに従
来の合金と比べて放電容量は大きく、長寿命を示すが、
電気化学的な初期活性化が遅く、充放電サイクルの初期
では放電容量が十分に得られないという問題があった。
これを解決する手段として、従来は合金成分や組成を変
えることで初期放電特性を改善しようとしてきたが、未
だ十分とはいえなかった。しかも、このことで実際の容
量が落ちてしまうこともあった。またこの他に、水素吸
蔵合金をアルカリ溶液に浸漬して、合金中の一部成分を
アルカリ溶液中に溶出させたり、反応生成物を生成させ
る等の表面処理を行うことによって初期特性を改善する
方法も試みられているが、若干の改善は見られるものの
満足できる成果が得られるまでには至っていない。本発
明は、上記問題点を解決するものであり、水素吸蔵合金
電極の高容量の特性を損なうことなく、サイクル初期の
放電特性を向上させることを目的とする。However, when the alloy having the AB 2 type Laves phase structure is used as the electrode, the discharge capacity is certainly larger than that of the conventional alloy, and the life is long.
There is a problem in that the initial electrochemical activation is slow, and a sufficient discharge capacity cannot be obtained at the beginning of the charge / discharge cycle.
As a means for solving this, conventionally, it has been attempted to improve the initial discharge characteristics by changing the alloy components and composition, but it has not been sufficient yet. Moreover, this may have reduced the actual capacity. In addition to this, the initial characteristics are improved by immersing the hydrogen storage alloy in an alkaline solution to elute some components in the alloy into the alkaline solution or by performing a surface treatment such as generating a reaction product. Methods have been tried, but some improvements have been seen, but the results have not been satisfactory. The present invention solves the above problems, and an object of the present invention is to improve the discharge characteristics at the beginning of a cycle without impairing the high capacity characteristics of the hydrogen storage alloy electrode.
【０００４】[0004]
【課題を解決するための手段】上記課題を解決するため
に、本発明のうち第１の発明は、前処理として水素吸蔵
合金に対し水素を吸蔵させ、その後、この水素吸蔵合金
にアルカリ溶液による表面処理を施すことを特徴とす
る。また第２の発明は、第１の発明において、水素吸蔵
処理後に水素吸蔵合金が吸蔵している水素量が、重量比
で５０ｐｐｍ以上であることを特徴とする。第３の発明
は、第１または第２の発明において、水素の吸蔵後、ア
ルカリ溶液による表面処理前に、水素吸蔵合金に対する
粉砕工程を有することを特徴とする。第４の発明は、第
１〜第３のいずれかの発明において水素吸蔵合金の結晶
構造がラーベス相構造であることを特徴とする。In order to solve the above-mentioned problems, the first invention of the present invention is that a hydrogen storage alloy is allowed to store hydrogen as a pretreatment, and then this hydrogen storage alloy is treated with an alkaline solution. It is characterized in that surface treatment is performed. A second invention is characterized in that, in the first invention, the amount of hydrogen stored in the hydrogen storage alloy after the hydrogen storage treatment is 50 ppm or more in weight ratio. A third invention is characterized in that, in the first or second invention, a crushing step for the hydrogen storage alloy is carried out after hydrogen storage and before surface treatment with an alkaline solution. A fourth invention is characterized in that, in any one of the first to third inventions, the crystal structure of the hydrogen storage alloy is a Laves phase structure.
【０００５】[0005]
【発明の実施の形態】本発明に用いられる水素吸蔵合金
の種別は、特に限定されないが、アルカリ溶液による表
面処理によって性能の改善が図られるものに好適であ
り、特にラーベス相構造の合金に好適である。具体的に
は、（Ｔｉ，Ｚｒ）Ｎｉ2系ＡＢ2型合金などが例示され
る。所定の成分およびその成分比を定めた水素吸蔵合金
は、常法により製造することができる。また、これら合
金は、水素の吸蔵前の形態が、ブロック状、粉末状のい
ずれであってもよい。BEST MODE FOR CARRYING OUT THE INVENTION The type of hydrogen storage alloy used in the present invention is not particularly limited, but is suitable for those whose performance is improved by surface treatment with an alkaline solution, and particularly suitable for Laves phase structure alloys. Is. Specifically, a (Ti, Zr) Ni 2 type AB 2 type alloy is exemplified. A hydrogen storage alloy having predetermined components and their component ratios can be manufactured by a conventional method. In addition, these alloys may have a block shape or a powder shape before hydrogen absorption.
【０００６】ただし、水素の吸蔵を効率よく行わせるた
めには粉末状の水素吸蔵合金を用いるのが望ましい。ま
た、同様にアルカリ溶液による表面処理前にも、表面処
理を効率的に行わせるためには、水素吸蔵合金が粉末状
であるのが望ましい。ここで、水素の吸蔵前にブロック
状であっても水素の吸蔵に伴って合金が粉末化される場
合もあるので、この粉末合金によっても表面処理が効率
的に行われる。ただし、水素の吸蔵と、アルカリ溶液の
表面処理との間には、作用面で関連性があるので、水素
吸蔵合金は、水素の吸蔵前から粉末状であるのがより望
ましい。However, it is desirable to use a powdery hydrogen storage alloy in order to efficiently store hydrogen. Similarly, before the surface treatment with the alkaline solution, in order to perform the surface treatment efficiently, it is desirable that the hydrogen storage alloy be in a powder form. Here, even if the alloy is in the form of a block before absorbing hydrogen, the alloy may be pulverized due to the absorption of hydrogen. Therefore, the surface treatment can be efficiently performed also with this powder alloy. However, since the hydrogen storage and the surface treatment of the alkaline solution are related in terms of action, it is more preferable that the hydrogen storage alloy be in a powder form before hydrogen storage.
【０００７】上記合金への水素の吸蔵は、通常は水素加
圧下の気相中で行われる。また水素の吸蔵処理に際して
は、水素の放出を含めて繰り返し吸蔵を行うこともでき
る。水素を合金に吸蔵させると、合金に大量の転位が導
入され、後の表面処理に際しアルカリ溶液中へのイオン
の溶出や反応生成物の生成が促進されることになる。ま
た、水素の吸蔵、放出によって水素吸蔵合金が脆化さ
れ、これにより合金が粉末化されたり、粉末状のものが
さらに微粉化されたりすることがあり、後の表面処理の
効果を高めることになる。また、粉砕工程を含む場合に
は粉砕が容易になる。さらに、水素吸蔵後においても合
金中に多くの水素が含まれていると、合金は体積膨張す
るとともに構成金属元素間の結合力が弱まった状態にな
り、上記表面処理における作用（イオンの溶出、反応生
成物の生成）が大幅に増す。この作用を十分に得るため
には、水素吸蔵処理後（アルカリ溶液による表面処理
前）に水素吸蔵合金が重量比で水素を５０ｐｐｍ以上含
有していることが必要であり、同様の理由で６５ｐｐｍ
以上含有しているのが望ましい。Storage of hydrogen in the above alloy is usually carried out in the gas phase under hydrogen pressure. In addition, during the hydrogen occlusion treatment, the occlusion including the release of hydrogen can be repeatedly performed. When hydrogen is stored in the alloy, a large amount of dislocations are introduced into the alloy, which promotes the elution of ions into the alkaline solution and the formation of reaction products during the subsequent surface treatment. In addition, hydrogen storage and release may cause the hydrogen storage alloy to become brittle, which may cause the alloy to be pulverized or the powdered substance to be further pulverized, which improves the effect of the subsequent surface treatment. Become. Further, when the crushing step is included, crushing becomes easy. Furthermore, when a large amount of hydrogen is contained in the alloy even after hydrogen storage, the alloy becomes volume-expanded and the bonding force between the constituent metal elements is weakened, and the action in the surface treatment (elution of ions, The formation of reaction products) is significantly increased. In order to obtain this effect sufficiently, it is necessary that the hydrogen storage alloy contains 50 ppm or more of hydrogen in a weight ratio after hydrogen storage treatment (before surface treatment with an alkaline solution), and 65 ppm for the same reason.
It is desirable to contain the above.
【０００８】さらに水素の吸蔵後、表面処理前には、水
素吸蔵合金への粉砕工程を設けることができる。この粉
砕工程では、水素吸蔵合金を粉末にしたり、粉末状の合
金をさらに微粉化したり、または／および粒径を揃える
ことを意図して合金の粉砕が行われる。なお、粉砕工程
における粉砕手段は特に限定されるものではなく、機械
的方法や物理化学的方法によって行うことができる。上
記した粉砕工程により、所望の粒径を有する水素吸蔵合
金が得られ、表面積の増大によって後の表面処理の効果
を一層高めることが可能になる。また、粒径を揃えたも
のにすれば、均質なアルカリ溶液による処理がなされ、
処理効果が一層顕著になる。なお、合金の表面積の増
大、粒径の揃いによって電池としての使用において水素
の吸蔵、放出効率が増し、放電容量が増大する効果もあ
る。Further, after occluding hydrogen and before surface treatment, a step of pulverizing the hydrogen occluding alloy can be provided. In this pulverizing step, the alloy is pulverized with the intention of making the hydrogen storage alloy into powder, further pulverizing the powdery alloy, and / or making the particle diameters uniform. The pulverizing means in the pulverizing step is not particularly limited, and can be performed by a mechanical method or a physicochemical method. By the above-mentioned pulverizing step, a hydrogen storage alloy having a desired particle size is obtained, and the effect of the subsequent surface treatment can be further enhanced by increasing the surface area. In addition, if the particle size is uniform, treatment with a homogeneous alkaline solution is performed,
The processing effect becomes more remarkable. The increase in the surface area of the alloy and the uniformity of the particle size also have the effect of increasing the efficiency of absorbing and releasing hydrogen and increasing the discharge capacity in use as a battery.
【０００９】前記した水素の吸蔵を行った水素吸蔵合金
は、その後、所望により上記した粉砕工程を行う場合も
含めて、アルカリ溶液による表面処理が行われる。この
表面処理は、通常、加熱したアルカリ溶液に水素吸蔵合
金を浸漬することによって行う。アルカリ溶液の種別
や、加熱温度、浸漬時間は特に限定されるものではな
く、適宜選定することができる。また、アルカリ溶液と
水素吸蔵合金との接触方法も浸漬に限定されるものでは
なく、他の方法によって行うことができる。アルカリ溶
液による表面処理では、従来法と同様に一部成分の溶
出、反応生成物の生成が行われるものの、予め水素の吸
蔵、またはこれに加えて粉砕が行われているので、上記
作用が効率よく、またより良好になされ、初期活性特性
が大幅に向上する。表面処理では、例えば、水素吸蔵合
金組成中のＭｎ、Ｃｏ等の成分がアルカリ溶液中に溶解
し、Ｍｍ等は水酸化物になり、Ｎｉ等は溶解せずに表層
に残る。溶解せずに残ったものが充放電にプラスに作用
し、特性を向上させることになる。The above hydrogen storage alloy that has absorbed hydrogen is then subjected to a surface treatment with an alkaline solution, including a case where the above-mentioned pulverization step is performed, if desired. This surface treatment is usually performed by immersing the hydrogen storage alloy in a heated alkaline solution. The type of the alkaline solution, the heating temperature, and the immersion time are not particularly limited, and can be appropriately selected. Also, the method of contact between the alkali solution and the hydrogen storage alloy is not limited to immersion, but may be performed by another method. In the surface treatment with an alkaline solution, although some components are eluted and reaction products are generated in the same manner as in the conventional method, since the hydrogen is occluded in advance, or in addition to this, pulverization is performed, the above-mentioned action is efficient Well and better done, the initial activation properties are greatly improved. In the surface treatment, for example, components such as Mn and Co in the hydrogen storage alloy composition are dissolved in the alkaline solution, Mm and the like become hydroxides, and Ni and the like remain in the surface layer without being dissolved. What remains without being dissolved acts positively on charge and discharge and improves the characteristics.
【００１０】上記した水素の吸蔵および表面処理を行っ
た水素吸蔵合金は、常法による加工工程等を経て電極に
使用される。その使用形態は特に限定されるものではな
く、電極として使用される種々の形態が含まれる。これ
ら処理を経た水素吸蔵合金を電池用の電極に使用するこ
とにより、高容量で、初期の放電容量が高く、耐久性に
も優れた電池が得られる。The above-mentioned hydrogen storage alloy which has been subjected to hydrogen storage and surface treatment is used for an electrode after undergoing a processing step by a conventional method. The form of use is not particularly limited, and includes various forms used as electrodes. By using the hydrogen storage alloy that has been subjected to these treatments for a battery electrode, a battery having a high capacity, a high initial discharge capacity, and an excellent durability can be obtained.
【００１１】[0011]
（実施例１）Ｚｒ、Ｍｎ、Ｖ、Ｎｉ、Ｃｏの各成分原料
それぞれ秤量して混合し、アーク式真空溶解装置のるつ
ぼ内に収納し、高純度Ａｒガス雰囲気下で溶解して、Ｚ
ｒＭｎ0.7Ｖ0.3Ｎｉ1.1Ｃｏ0.1の組成の水素吸蔵合金の
インゴットを作製した。次いでＡｒガス雰囲気中におい
て、１１００℃で４時間の熱処理を行い、合金試料とし
た。得られた合金は、さらに大気中で５０〜２００メッ
シュに予備粉砕した。次いで、この粉末を、４５ｋｇ／
ｃｍ2の水素加圧下、２５〜２００℃の温度範囲で、水
素の吸蔵、放出を３回繰返した。これらの水素吸蔵、放
出に伴って水素吸蔵合金は、微粉砕された（１０〜５０
μｍ）。なお、水素吸蔵処理後の合金中の水素含有量は
重量比で６９ｐｐｍであった。これをさらに粉砕工程と
してアルミナ乳ばち中で粉砕（１０μｍ以下）した後、
８０℃の６Ｍ ＫＯＨ水溶液中に１．５時間浸漬する表
面処理を行った。その後、これを水洗いし、乾燥した。(Example 1) Zr, Mn, V, Ni, and Co component materials were weighed and mixed, stored in a crucible of an arc type vacuum melting apparatus, melted in a high-purity Ar gas atmosphere, and Z
A hydrogen storage alloy ingot having a composition of rMn 0.7 V 0.3 Ni 1.1 Co 0.1 was prepared. Then, heat treatment was performed at 1100 ° C. for 4 hours in an Ar gas atmosphere to obtain an alloy sample. The obtained alloy was further pre-ground to 50-200 mesh in the atmosphere. Next, 45 kg /
Under hydrogen pressure of cm 2 , hydrogen absorption and desorption was repeated 3 times in the temperature range of 25 to 200 ° C. The hydrogen storage alloy was finely pulverized (10 to 50) along with the hydrogen storage and release.
μm). The hydrogen content in the alloy after the hydrogen storage treatment was 69 ppm by weight. After further crushing (10 μm or less) in an alumina bean as a crushing step,
Surface treatment was carried out by immersing in a 6 M KOH aqueous solution at 80 ° C. for 1.5 hours. Then, it was washed with water and dried.
【００１２】次に以上の処理をした合金粉末０．２５ｇ
とＣｕ粉末０．７５ｇを混合し、この混合体を加圧成形
して、直径２ｃｍのペレットとし、このペレットをＮｉ
網（５０メッシュ）ではさんで電池の負極用電極とし
た。上記電極の対極には、焼結式Ｎｉ極を用い、参照極
には酸化水銀電極、電解液には６Ｍ ＫＯＨ水溶液を用
いて電池を構成した。次いで、上記電池を２５℃の恒温
水槽中で、０．２ｃ、６時間の充電を行い、１０分の休
止後、０．２ｃで放電した。なお、終止電圧は、−０．
８Ｖ（ｖｓ参照極）とした。この操作を１サイクルとし
て、繰返し充放電を行い、各サイクルの放電容量を測定
した。Next, 0.25 g of the alloy powder treated as described above
And Cu powder 0.75 g are mixed, and this mixture is pressure-molded to form a pellet having a diameter of 2 cm.
It was sandwiched by a mesh (50 mesh) to form a negative electrode for the battery. A sintered Ni electrode was used as the counter electrode of the above electrode, a mercury oxide electrode was used as the reference electrode, and a 6M KOH aqueous solution was used as the electrolytic solution to construct a battery. Then, the battery was charged in a constant temperature water bath at 25 ° C. for 0.2 c for 6 hours, and after 10 minutes of rest, discharged at 0.2 c. The final voltage is −0.
8V (vs reference electrode). This operation was set as one cycle, charging and discharging were repeated, and the discharge capacity of each cycle was measured.
【００１３】比較例としては、上記と同様にして予備粉
砕した粉末試料に対し、前処理としての水素の吸蔵を行
っていないもの（比較例２）、８０℃、６Ｍ ＫＯＨ水
溶液中の浸漬を行っていないもの（比較例３）、これら
のいずれの処理も行っていないもの（比較例１）を用意
し、それぞれの合金を用いて上記と同様にして電池を構
成し、放電容量を測定した。なお、比較例３による合金
の水素吸蔵処理後の水素量は、発明材とほぼ同程度で約
７０ｐｐｍであった。放電容量測定の結果、表１および
図１に示すように発明材は比較材と同等以上の最大放電
容量を有しており、高容量の特性は損なわれておらず、
却って僅かながらも向上している。また、比較材では最
大放電容量に達するのに２０サイクル以上かけているの
に対し、本発明の処理を行ったものは、６サイクルで最
大容量値に達しており、さらに、比較材の１サイクル目
はいずれも最大容量の３０％以下しかないのに対し本発
明の処理を行ったものは、１サイクル目ですでにその８
４％を示している。以上のように、本発明法により得ら
れた電極を使用した電池では、最大放電容量に優れてい
るだけでなく、初期活性特性が大幅に改善されているこ
とが判明した。As a comparative example, a powder sample preliminarily crushed in the same manner as described above was not subjected to hydrogen storage as a pretreatment (Comparative Example 2), but was immersed in a 6M KOH aqueous solution at 80 ° C. A sample not prepared (Comparative Example 3) and a sample not subjected to any of these treatments (Comparative Example 1) were prepared, and a battery was constructed using each alloy in the same manner as above, and the discharge capacity was measured. The hydrogen content of the alloy according to Comparative Example 3 after the hydrogen storage treatment was about 70 ppm, which was almost the same as that of the invention material. As a result of the discharge capacity measurement, as shown in Table 1 and FIG. 1, the invention material has a maximum discharge capacity equal to or higher than that of the comparative material, and the high capacity characteristics are not impaired.
On the contrary, it is slightly improved. Further, in the comparative material, it took 20 cycles or more to reach the maximum discharge capacity, whereas in the case where the treatment of the present invention was performed, the maximum capacity value was reached in 6 cycles. All the eyes have 30% or less of the maximum capacity, whereas the ones which have been treated according to the present invention already have 8
4% is shown. As described above, it was found that the battery using the electrode obtained by the method of the present invention was not only excellent in the maximum discharge capacity, but also significantly improved in the initial activation characteristics.
【００１４】[0014]
【表１】 [Table 1]
【００１５】（実施例２）実施例１と同様の方法で得ら
れた水素吸蔵合金粉末（予備粉砕後）に対し、２５℃に
て４５ｋｇ／ｃｍ2の水素圧を印加し水素を吸蔵させ
た。その後、合金中の水素濃度を種々変化させる目的
で、２０℃〜４００℃の種々の温度にて１時間の真空脱
ガスを行い、水素を放出させた。このような種々の脱ガ
ス条件にて水素放出させた合金中には、脱ガス後に、３
９ｐｐｍ〜２０００ｐｐｍの範囲で水素吸蔵が認められ
た。これらの合金について、実施例１と同様にして表面
処理した後、電池を構成し、同じ条件にて充放電試験を
行った。これらのうち水素吸蔵量が最も少ないもの（３
９ｐｐｍ）と最も多いもの（２０００ｐｐｍ）について
放電特性を図２に示した。図２から明らかなように、両
者間で特性に差はあるもののいずれの電池も実施例１に
示された比較例１〜３（図１参照）よりも初期活性特
性、放電容量ともに大幅に改善されている。また、図３
に、合金中に吸蔵された水素濃度と初期放電容量との関
係を示す。図から明らかなように水素吸蔵の操作を行っ
ていない合金でも１０ｐｐｍ程度の水素が含まれている
が、この程度の水素量では初期活性化特性は改善され
ず、水素吸蔵処理の結果、５０ｐｐｍ以上の水素を吸蔵
していることにより初期活性が大きく改善されている。
したがって、より大きくて顕著な効果を得るためには、
表面処理前に水素の吸蔵処理を行い、しかも水素吸蔵処
理後にある程度以上（５０ｐｐｍ以上）の水素が含有さ
れていることが必要になる。(Example 2) Hydrogen-absorbing alloy powder obtained by the same method as in Example 1 (after preliminary pulverization) was applied with a hydrogen pressure of 45 kg / cm 2 at 25 ° C to occlude hydrogen. . After that, for the purpose of variously changing the hydrogen concentration in the alloy, vacuum degassing was performed at various temperatures of 20 ° C. to 400 ° C. for 1 hour to release hydrogen. In an alloy in which hydrogen is released under such various degassing conditions, after degassing, 3
Hydrogen storage was observed in the range of 9 ppm to 2000 ppm. After surface-treating these alloys in the same manner as in Example 1, a battery was constructed and a charge / discharge test was conducted under the same conditions. Of these, the one with the smallest hydrogen storage capacity (3
The discharge characteristics of the largest amount (9 ppm) (2000 ppm) are shown in FIG. As is apparent from FIG. 2, although there is a difference in characteristics between the two, all the batteries have significantly improved both initial activation characteristics and discharge capacity as compared with Comparative Examples 1 to 3 (see FIG. 1) shown in Example 1. Has been done. FIG.
Shows the relationship between the concentration of hydrogen absorbed in the alloy and the initial discharge capacity. As can be seen from the figure, even alloys not subjected to hydrogen storage operation still contain about 10 ppm of hydrogen, but with this amount of hydrogen, the initial activation characteristics were not improved, and as a result of hydrogen storage treatment, 50 ppm or more The initial activity is greatly improved by occluding hydrogen.
Therefore, in order to obtain a larger and noticeable effect,
It is necessary to perform hydrogen absorption treatment before the surface treatment, and to contain a certain amount of hydrogen (50 ppm or more) after the hydrogen absorption treatment.
【００１６】[0016]
【発明の効果】以上説明したように、本発明によれば、
前処理として水素吸蔵合金に対し水素を吸蔵させ、その
後、この水素吸蔵合金にアルカリ溶液による表面処理を
施すので、放電容量を変えることなく、初期放電特性が
飛躍的に優れた電極を作製することができる。さらに、
上記水素吸蔵処理後に合金に５０ｐｐｍ以上の水素が含
有されているものとすれば、初期放電特性の改善は顕著
になる。また、水素の吸蔵後、アルカリ溶液による表面
処理前に、水素吸蔵合金に対する粉砕工程を設ければ、
アルカリ溶液による表面処理が一層効率的になり、ま
た、合金の表面積が増大することによって充放電特性も
向上する。さらに、水素吸蔵合金として、結晶構造がラ
ーベス相構造で合金を使用すれば、高容量、長寿命の電
池が得られ、また、アルカリ溶液による表面処理効果が
大きく、本発明による斯かる効果の向上によって初期放
電特性が大幅に向上する。As described above, according to the present invention,
As a pretreatment, the hydrogen storage alloy is allowed to store hydrogen, and then this hydrogen storage alloy is subjected to surface treatment with an alkaline solution, so that an electrode with dramatically superior initial discharge characteristics can be produced without changing the discharge capacity. You can further,
If the alloy contains 50 ppm or more of hydrogen after the above hydrogen storage treatment, the initial discharge characteristics will be significantly improved. Further, after the hydrogen storage, before the surface treatment with the alkaline solution, if a crushing step for the hydrogen storage alloy is provided,
The surface treatment with the alkaline solution becomes more efficient, and the surface area of the alloy is increased, so that the charge / discharge characteristics are also improved. Furthermore, when an alloy having a Laves phase crystal structure is used as the hydrogen storage alloy, a battery having a high capacity and a long life can be obtained, and the surface treatment effect by the alkaline solution is large, and the effect of the present invention is improved. As a result, the initial discharge characteristics are significantly improved.
【図１】 本発明の実施例における発明法と比較法によ
り得られた電池の放電容量特性を比較するグラフであ
る。FIG. 1 is a graph comparing the discharge capacity characteristics of the batteries obtained by the inventive method and the comparative method in the examples of the present invention.
【図２】 同じく、発明法により得られた電池の放電容
量特性を比較するグラフである。FIG. 2 is likewise a graph comparing the discharge capacity characteristics of the batteries obtained by the method of the invention.
【図３】 同じく、合金中の水素残留量による初期放電
特性の変化を示すグラフである。FIG. 3 is likewise a graph showing changes in initial discharge characteristics depending on the amount of hydrogen remaining in the alloy.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 兜森 俊樹 北海道室蘭市茶津町４番地 株式会社日本 製鋼所内 (72)発明者 脇坂 裕一 北海道室蘭市茶津町４番地 株式会社日本 製鋼所内 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toshiki Kabumori 4th Chazu Town, Muroran City, Hokkaido, Japan Steel Works, Ltd. (72) Inventor Yuichi Wakisaka 4th Chazu Town, Muroran City, Hokkaido Japan Steel Works, Ltd.
Claims (4)
吸蔵させ、その後、この水素吸蔵合金にアルカリ溶液に
よる表面処理を施すことを特徴とする水素吸蔵合金電極
の製造方法1. A method for producing a hydrogen storage alloy electrode, characterized in that hydrogen is stored in a hydrogen storage alloy as a pretreatment, and then the hydrogen storage alloy is subjected to a surface treatment with an alkaline solution.
ている水素量が、重量比で５０ｐｐｍ以上であることを
特徴とする請求項１記載の水素吸蔵合金電極の製造方法2. The method for producing a hydrogen storage alloy electrode according to claim 1, wherein the amount of hydrogen stored in the hydrogen storage alloy after the hydrogen storage treatment is 50 ppm or more in weight ratio.
処理前に、水素吸蔵合金に対する粉砕工程を有すること
を特徴とする請求項１または２に記載の記載の水素吸蔵
合金電極の製造方法3. The method for producing a hydrogen storage alloy electrode according to claim 1, further comprising a pulverization step for the hydrogen storage alloy after hydrogen storage and before surface treatment with an alkaline solution.
構造であることを特徴とする請求項１〜３のいずれかに
記載の水素吸蔵合金電極の製造方法4. The method for producing a hydrogen storage alloy electrode according to claim 1, wherein the hydrogen storage alloy has a Laves phase structure in its crystal structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8040583A JPH09213317A (en) | 1996-02-02 | 1996-02-02 | Manufacture of hydrogen storage alloy electrode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8040583A JPH09213317A (en) | 1996-02-02 | 1996-02-02 | Manufacture of hydrogen storage alloy electrode |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH09213317A true JPH09213317A (en) | 1997-08-15 |
Family
ID=12584525
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8040583A Pending JPH09213317A (en) | 1996-02-02 | 1996-02-02 | Manufacture of hydrogen storage alloy electrode |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH09213317A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003533854A (en) * | 2000-05-17 | 2003-11-11 | ホガナス アクチボラゲット | Method for improving the properties of alloy powder for NiMH batteries |
| JP2015210865A (en) * | 2014-04-24 | 2015-11-24 | トヨタ自動車株式会社 | Hydrogen absorbing alloy particle |
-
1996
- 1996-02-02 JP JP8040583A patent/JPH09213317A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003533854A (en) * | 2000-05-17 | 2003-11-11 | ホガナス アクチボラゲット | Method for improving the properties of alloy powder for NiMH batteries |
| JP2015210865A (en) * | 2014-04-24 | 2015-11-24 | トヨタ自動車株式会社 | Hydrogen absorbing alloy particle |
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