JPS6276255A - Hydrogen occlusion electrode - Google Patents

Abstract

PURPOSE:To lengthen the cycle life of charge/discharge by preparing alloy of specific chemical formula while having a crystal structure of CaCu5 structure where cobalt is contained in mish metal-nickel system alloy as hydrogen occlusion material. CONSTITUTION:An alloy where cobelt is contained in mish metal-nickel system alloy while having a crystal structure of CaCu5 structure and a chemical formula represented by MnNixCoy, where, 3>=x>=2, 2<=y<=3 and 4.5<=x+y<=5.5 is prepared as hydrogen occlusion material. 80wt% of such hydrogen occlusion alloy powder, 10wt% of acetylene black as conductive material and 10wt% of fluororesin powder and mixed uniformly while fluororesin is fiberized. Then the compound is wrapped up in nickel mesh and pressure molded to produce hydrogen occlusion electrode.

Description

【発明の詳細な説明】 （イ）産業上の利用分野 本発明はアルカリ蓄電池の負極として用いられる水素吸
蔵電極に関し、特に高容量を長期にわたって維持するよ
う改良された水素吸蔵電極に関する。DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a hydrogen storage electrode used as a negative electrode of an alkaline storage battery, and more particularly to a hydrogen storage electrode that has been improved to maintain high capacity over a long period of time.

（ロ）従来の技術 従来からよく用いられる蓄電池として鉛電池及びニッケ
ルーカドミウム電池があるが、近年これら電池より軽量
で且つ高容量となる可能性があるということで、特に低
圧に於いて負極活物質であろ水素を可逆的に吸蔵及び放
出することのできる水素吸蔵合金を備えた電極を負極に
用い、水酸化ニッケルなどの金属酸化物からなる正極活
物質を備えた！極を正極に用いた金属−水素アルカリ蓄
電池が注目されている。(b) Conventional technology Lead-acid batteries and nickel-cadmium batteries have traditionally been commonly used storage batteries, but in recent years they have been shown to be lighter than these batteries and have the potential to have higher capacities, so negative electrode activation has been developed, especially at low pressures. The negative electrode is an electrode equipped with a hydrogen storage alloy that can reversibly absorb and release hydrogen, and the positive electrode active material is made of a metal oxide such as nickel hydroxide! Metal-hydrogen alkaline storage batteries using the electrode as the positive electrode are attracting attention.

一般にこの種蓄電池に用いられる水素吸蔵合金を備えた
水素吸蔵電極は特公昭５８−４６８２７号公報に於いて
提案されているように水素を吸蔵する合金粉末と水素を
吸蔵しない合金粉末との混合物を焼結して焼結多孔体を
作製し、これを水素吸蔵Ｎ、極とする方法、あるいは特
開昭５３−１０３５４１号公報に於いて提案きれている
ように水素を吸蔵する合金粉末とアセチレンブラック及
び電極支持体とを耐電解液性の粒子状結着剤により相互
に結合させて水素吸蔵電極とする方法によって作製され
ており、これら電極に用いる水素吸蔵合金として、特公
昭５９−４９６７１号公報に於いてＬａＮ１ａＣｏ。Hydrogen storage electrodes equipped with hydrogen storage alloys that are generally used in this type of storage battery are made by using a mixture of alloy powders that store hydrogen and alloy powders that do not store hydrogen, as proposed in Japanese Patent Publication No. 58-46827. A method of producing a sintered porous body by sintering and using this as a hydrogen-absorbing N, pole, or using an alloy powder that absorbs hydrogen and acetylene black as proposed in JP-A-53-103541. and an electrode support are bonded to each other using a particulate binder that is resistant to electrolytic solution to form a hydrogen storage electrode, and a hydrogen storage alloy used in these electrodes is disclosed in Japanese Patent Publication No. 59-49671. In LaN1aCo.

ＬａＮ１ａＣｏ、ＬａＮｉ＋、Ｆｅｏ、＊　、ＬａＮｉ
５などが提案されている。しかしながら、これら水素吸
蔵合金を水素吸蔵材として備えた水素吸蔵電極は、充放
電サイクルの経過に伴い放電容量が減少し、す１′タル
寿命が短くなるため満足できるものではなかった。LaN1aCo, LaNi+, Feo, *, LaNi
5 etc. have been proposed. However, hydrogen storage electrodes equipped with these hydrogen storage alloys as hydrogen storage materials have been unsatisfactory because their discharge capacity decreases with the passage of charge/discharge cycles and their total lifespans become short.

（ハ）発明が解決しようとする問題点 本発明は充放電によるサイクル寿命の長い水素吸蔵電極
を得ようとするものである。(c) Problems to be Solved by the Invention The present invention attempts to obtain a hydrogen storage electrode that has a long cycle life during charging and discharging.

（ニ）問題点を解決するだめの手段 本発明の水素吸蔵Ｗ極は、水素吸蔵材としてミンシュメ
タルーニッケル系合金にコバルトヲ含有させてなり、Ｃ
ａＣｕａ構造の結晶構造を有し、且つ化学式がＭｍＮ　
Ｉ　ｘ　Ｃｏ　ｙで表ゎきれ、Ｘが３≧Ｘ≧２、ｙが２
≦ｙ≦３、ｚ＋ｙが４．５≦ｚ＋ｙ≦５．５の範囲内で
ある合金を備えたものである。(d) Means for solving the problem The hydrogen storage W pole of the present invention is made by adding cobalt to a minsch metal-nickel alloy as a hydrogen storage material.
It has the aCua crystal structure and the chemical formula is MmN.
I x Co y can be expressed, X is 3≧X≧2, y is 2
The alloy has an alloy in which ≦y≦3 and z+y is within the range of 4.5≦z+y≦5.5.

（ホ）作用 Ｃａ　Ｃｕ　６構造の結晶構造を有し、且つ化学式がＭ
ｍＮｉｘＣｏｙで表わされ、Ｘが３≧Ｘ≧２、ｙが２≦
ｙ≦３、ｘ＋ｙが４．５≦ｘ＋ｙ≦５．５の範囲内にあ
る合金を備えた水素吸蔵電極は、充放電によるサイクル
寿命が伸び、放電容量が増大する。(e) It has a crystal structure of functional Ca Cu 6 structure, and the chemical formula is M
It is expressed as mNixCoy, where X is 3≧X≧2, and y is 2≦
A hydrogen storage electrode including an alloy in which y≦3 and x+y are within the ranges of 4.5≦x+y≦5.5 has a longer cycle life during charging and discharging, and an increased discharge capacity.

〈ホ）実施例 市販のミンシュメタル、ニッケル、コバルトヲ組成比Ｍ
ｍ二Ｎｊ：Ｃｏ−１：３：２になるよう混合し、アーク
溶解炉に入れて加熱、溶解して合金化した後粉砕して、
結晶構造がＣａＣｕ５構造をとるＬ　ａ　Ｎ　ｉ　ｓ　
ＣＯ！粉末を得た。また同様にして混合、合金化及び粉
砕という操作を行なって、結晶構造がＣａＣｕｇ構造で
あり組成が種々異なる各種水素吸蔵合金粉末を得た。こ
うして得られた各種水素吸蔵合金粉末８０ｆｆｉ量％、
導電材としてのアセチレンブラック１０重量％及び結着
剤としてのフッ素樹脂粉末１０重量％を混合機で均一に
混合すると共にフッ素樹脂をｍ維化する。そして得られ
た混線物を二・７ケル金網で包み込み３ｔｏｎ／ｃＩＴ
Ｉ２で加圧成型することにより、外面がニッケル金網で
覆われた水素吸蔵電極を作製した。この外面がニッケル
金網で覆われた構造の水素吸蔵電極は、充電時に電極中
の水素吸蔵合金が水素を吸蔵すると共に水素ガスを発生
して生じる電極の膨張を前記二／ケル金網によって機械
的に抑え、この１極の膨張による機械的強度の劣化及び
それに伴う水素吸蔵合金の脱落が抑えられて充放電の繰
り返しによる性能の早期低下を抑制する。尚、これら水
素吸蔵電極に用いた合金粉末は夫々的１．５ｇである。(e) Example Composition ratio M of commercially available minshmetal, nickel, and cobalt
m2Nj:Co-1:3:2, mixed, put in an arc melting furnace, heated, melted and alloyed, then crushed,
L a N i s whose crystal structure is CaCu5 structure
CO! A powder was obtained. Further, by performing the same operations of mixing, alloying, and pulverizing, various hydrogen storage alloy powders having a CaCug crystal structure and having various compositions were obtained. 80ffi amount% of various hydrogen storage alloy powders obtained in this way,
10% by weight of acetylene black as a conductive material and 10% by weight of fluororesin powder as a binder are uniformly mixed in a mixer and the fluororesin is turned into m-fibers. Then, the resulting mixed material was wrapped in a 2.7K wire mesh and the amount of 3ton/cIT
A hydrogen storage electrode whose outer surface was covered with a nickel wire mesh was produced by pressure molding with I2. This hydrogen storage electrode has a structure in which the outer surface is covered with a nickel wire mesh. During charging, the hydrogen storage alloy in the electrode absorbs hydrogen and generates hydrogen gas, which causes expansion of the electrode. This suppresses the deterioration of mechanical strength due to the expansion of this single pole and the resulting drop-off of the hydrogen storage alloy, thereby suppressing early deterioration of performance due to repeated charging and discharging. The amount of alloy powder used for each of these hydrogen storage electrodes was 1.5 g.

次いで丑記水素吸蔵電極を夫々理論容量が６００ｍＡＨ
の焼結式ニッケル正極と組合わせ電解液に水酸化カリウ
ム水溶液を用いて密閉型ニッケルー水素アルカリ蓄電池
を種々作製し、負極に用いた水素吸蔵合金の種類により
、表１表に示す如く電池Ａ乃至Ｈとする。Next, the hydrogen storage electrodes described above each have a theoretical capacity of 600 mAH.
Various sealed nickel-hydrogen alkaline storage batteries were prepared using a sintered nickel positive electrode and an aqueous potassium hydroxide solution as the electrolyte. Let it be H.

これらの電池を０．２５Ｃ電流で５時間充電した後、０
．５Ｃ’ｉ：流で放電して電池電圧が１．ＯＶになった
時点で放電停止するサイクル条件で充放電を繰り返して
１池性能を測定し、各電池の初期容量を夫々１００とし
てそのサイクル特性を第１図に示すと共に各電池のサイ
クル寿命を第２図に示す。After charging these batteries with 0.25C current for 5 hours, 0
．． 5C'i: The battery voltage is 1. The performance of one battery was measured by repeating charging and discharging under cycle conditions in which discharging was stopped when the battery reached OV. The initial capacity of each battery was assumed to be 100, and the cycle characteristics are shown in Figure 1, and the cycle life of each battery was calculated as follows. Shown in Figure 2.

以下余白 第　　１　　表 第１図及び第２図から明らかなようにＭ　ｍ　Ｎ　ｉ。Margin below Table 1 As is clear from FIGS. 1 and 2, M m N i.

をベースとしＮｉをＣｏに置換する量を種々変化させて
作製した水吸蔵合金を負極の水素吸蔵材とする電池Ａ乃
至Ｆの中でも、電池Ｂ、Ｃ，Ｄ及びＥがＬａＮ（ａやＬ
　ａ　Ｎ　ｉ　４Ｃｕを負極の水素吸蔵材とする電池よ
りもサイクル特性が良好であり、特に電池Ｃ及びＤのサ
イクル特性が優れている。Among the batteries A to F in which the hydrogen storage material of the negative electrode is a water storage alloy prepared by varying the amount of replacing Ni with Co based on LaN (a and L), batteries B, C, D, and E are
The cycle characteristics are better than batteries using aN i 4Cu as the negative electrode hydrogen storage material, and the cycle characteristics of Batteries C and D are particularly excellent.

上記の如＜、ＭｍＮｉ５Ｃｏ＊及びＭｍＮＬＣｏｓを負
極の水素吸蔵材として用いた電池Ｃ及びＤが特に優れた
特性を有することが判明したので、更にこれらＭｍＮｉ
５Ｃｏ＊及びＭｍＮｉ、Ｃｏｓの組成のうち、Ｎｉ及び
Ｃｏの組成比を若干変化させて第２表に示すような水素
吸蔵合金を作製し、前述同様これら水素吸蔵合金を負極
の水素吸蔵材として用いたニッケルー水素蓄電池を得、
水素吸蔵合金の種類により電池！乃至Ｏとする。As mentioned above, it was found that batteries C and D using MmNi5Co* and MmNLCos as negative electrode hydrogen storage materials had particularly excellent characteristics.
Among the compositions of 5Co*, MmNi, and Cos, hydrogen storage alloys as shown in Table 2 were prepared by slightly changing the composition ratios of Ni and Co, and these hydrogen storage alloys were used as hydrogen storage materials for negative electrodes as described above. Obtained a nickel-metal hydride storage battery,
Batteries depending on the type of hydrogen storage alloy! 〜O.

第　　２　　表 第３図は上記電池■乃至０と電池Ｃ及びＤを前述と同様
のサイクル条件で測定したサイクル特性を示１図面であ
る。これら電池の中でも電池Ｉ乃至Ｍと電池Ｃ及びＤの
サイクル特性が電池Ｎ及び○より侵れることから、Ｍｍ
ＮｉｘＣｏｙの化学式で示きれるもののうち特にＸが３
≧Ｘ≧２、ｙが２≦ｙ≦３、Ｘ＋、Ｆが４．５≦ｘ＋ｙ
≦５．５の範囲にある水素吸蔵合金を備えた水素吸蔵電
極を負極に用いることにより優れた特性が得られること
がわかる。Table 2 and Figure 3 are graphs showing the cycle characteristics of the batteries 1 to 0 and batteries C and D measured under the same cycle conditions as described above. Among these batteries, the cycle characteristics of Batteries I to M and Batteries C and D are worse than Batteries N and ○, so Mm
Of the things that can be shown by the NixCoy chemical formula, especially when X is 3
≧X≧2, y is 2≦y≦3, X+, F is 4.5≦x+y
It can be seen that excellent characteristics can be obtained by using a hydrogen storage electrode having a hydrogen storage alloy in the range of ≦5.5 as the negative electrode.

（ト）発明の効果 本発明の水素吸蔵電極は、水素吸蔵材としミッシュメタ
ル−ニッケル系合金にコバルトを含有きせてなり、Ｃａ
Ｃｕ５構造の結晶構造を有し、且つ化学式がＭｒｒｒＮ
ｉｘＣｏｙで表わされ、Ｘが３≧Ｘ≧２、ｙが２≦ｙ≦
３、Ｘ−１−３１が４．５≦Ｘ＋ｙ≦５．５の範囲内に
ある合金を備えたものであり、サイクル特性の向上をも
たらすものであるから、この水素吸蔵電極を負極に用い
ることにより、優れた性能の蓄電池を提供することがで
き、その工業的価値は極めて大きい。(G) Effects of the Invention The hydrogen storage electrode of the present invention is made by adding cobalt to a misch metal-nickel alloy as a hydrogen storage material.
It has a crystal structure of Cu5 structure and the chemical formula is MrrrN
It is expressed as ixCoy, where X is 3≧X≧2, and y is 2≦y≦
3. Since X-1-31 includes an alloy in the range of 4.5≦X+y≦5.5 and improves cycle characteristics, this hydrogen storage electrode can be used as a negative electrode. As a result, a storage battery with excellent performance can be provided, and its industrial value is extremely large.

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

第１図乃至第３図は各種水素吸蔵合金を備えた水素吸蔵
電極を負極に用いた電池の特性を示す図面であり、第１
図及び第３図はサイクル特性図、第２図はサイクル寿命
を示す図面である。Figures 1 to 3 are drawings showing the characteristics of a battery using a hydrogen storage electrode equipped with various hydrogen storage alloys as a negative electrode.
3 and 3 are cycle characteristic diagrams, and FIG. 2 is a diagram showing cycle life.

Claims (1)

【特許請求の範囲】[Claims] （１）ミッシュメタル−ニッケル系合金にコバルトを含
有させてなり、ＣａＣｕ＿５構造の結晶構造を有し、且
つ化学式がＭｍＮｉｘＣｏｙで表わされ、ｘが３≧ｘ≧
２、ｙが２≦ｙ≦３、ｘ＋ｙが４．５≦ｘ＋ｙ≦５．５
の範囲内である合金を備えたことを特徴とする水素吸蔵
電極。(1) Misch metal - made of a nickel-based alloy containing cobalt, has a crystal structure of CaCu_5 structure, and has a chemical formula of MmNixCoy, where x is 3≧x≧
2, y is 2≦y≦3, x+y is 4.5≦x+y≦5.5
A hydrogen storage electrode characterized by comprising an alloy within the range of .