JPH11350001A - Hydrogen storage sintering material and negative electrode for alkaline storage battery - Google Patents
Hydrogen storage sintering material and negative electrode for alkaline storage batteryInfo
- Publication number
- JPH11350001A JPH11350001A JP10154359A JP15435998A JPH11350001A JP H11350001 A JPH11350001 A JP H11350001A JP 10154359 A JP10154359 A JP 10154359A JP 15435998 A JP15435998 A JP 15435998A JP H11350001 A JPH11350001 A JP H11350001A
- Authority
- JP
- Japan
- Prior art keywords
- hydrogen storage
- alloy
- sintering
- grain size
- alloy powder
- 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
- 238000003860 storage Methods 0.000 title claims abstract description 54
- 239000001257 hydrogen Substances 0.000 title claims abstract description 45
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 45
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 42
- 238000005245 sintering Methods 0.000 title claims abstract description 29
- 239000000463 material Substances 0.000 title claims abstract description 10
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 78
- 239000000956 alloy Substances 0.000 claims abstract description 78
- 239000000843 powder Substances 0.000 claims abstract description 25
- 238000010298 pulverizing process Methods 0.000 claims abstract description 17
- 239000011261 inert gas Substances 0.000 claims abstract description 8
- 239000002245 particle Substances 0.000 claims description 31
- 238000000465 moulding Methods 0.000 claims 1
- 238000009826 distribution Methods 0.000 abstract description 15
- 229910052751 metal Inorganic materials 0.000 abstract description 8
- 239000002184 metal Substances 0.000 abstract description 8
- 239000000203 mixture Substances 0.000 abstract description 8
- 238000010438 heat treatment Methods 0.000 abstract description 5
- 229910052777 Praseodymium Inorganic materials 0.000 abstract description 4
- 238000012856 packing Methods 0.000 abstract description 4
- 239000011148 porous material Substances 0.000 abstract description 4
- 229910052761 rare earth metal Inorganic materials 0.000 abstract description 4
- 229910052779 Neodymium Inorganic materials 0.000 abstract description 3
- 229910052684 Cerium Inorganic materials 0.000 abstract description 2
- 229910052746 lanthanum Inorganic materials 0.000 abstract description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 8
- 239000001301 oxygen Substances 0.000 description 8
- 229910052760 oxygen Inorganic materials 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- 229910052799 carbon Inorganic materials 0.000 description 7
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 6
- 239000011362 coarse particle Substances 0.000 description 6
- 238000011109 contamination Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 229910052786 argon Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000011049 filling Methods 0.000 description 4
- 239000010419 fine particle Substances 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 230000004913 activation Effects 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 239000001307 helium Substances 0.000 description 3
- 229910052734 helium Inorganic materials 0.000 description 3
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 239000007773 negative electrode material Substances 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- BFDHFSHZJLFAMC-UHFFFAOYSA-L nickel(ii) hydroxide Chemical compound [OH-].[OH-].[Ni+2] BFDHFSHZJLFAMC-UHFFFAOYSA-L 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- -1 that is Substances 0.000 description 2
- 229910004247 CaCu Inorganic materials 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052745 lead Inorganic materials 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000000615 nonconductor Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 235000011118 potassium hydroxide Nutrition 0.000 description 1
- 239000011802 pulverized particle Substances 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 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
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、水素を吸蔵・放出
する水素吸蔵燒結材料に関するものであり、特にアルカ
リ蓄電池の負極材料およびアルカリ蓄電池に関するもの
である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen storage and sintering material for storing and releasing hydrogen, and more particularly to a negative electrode material for an alkaline storage battery and an alkaline storage battery.
【０００２】[0002]
【従来技術】水素吸蔵合金は、電気化学的にその水素を
吸蔵・放出させることができることにより、２次電池の
負極電極材料として利用されている。該合金は、電極の
充放電の際、水素化（充電）、脱水素化（放電）される
ためその体積変動を伴う。そのため、該合金をそのまま
の状態で負極として用いると割れを生じ、微粉化し電極
から脱落し放出容量を低下させるという問題があった。2. Description of the Related Art A hydrogen storage alloy is used as a negative electrode material of a secondary battery because it can electrochemically store and release hydrogen. The alloy is hydrogenated (charged) and dehydrogenated (discharged) at the time of charging and discharging the electrodes, so that the volume of the alloy varies. Therefore, when the alloy is used as it is as a negative electrode, there is a problem that cracks are generated, the alloy is pulverized, drops from the electrode, and the release capacity is reduced.
【０００３】このような問題に対し、従来より一般のペ
ースト式電極とよばれる製造方法は、水素吸蔵合金を数
１０μｍに粉砕し、ポリビニルアルコール等の結合剤を
用いペースト化し、パンチングメタルや発泡ニッケルと
いった支持体に該ペーストを塗布させることにより脱落
を防止していた。しかしながら、結合剤、支持体および
セパレータは、電池として用いた場合、水素吸蔵放出に
預からないため、一定体積（電池）に対する水素吸蔵合
金の充填量は小さい。それに対し、水素吸蔵合金を粉砕
し、直接焼結させて電極とすることで割れに対する強度
を向上させる方法が考えられていた。[0003] In response to such a problem, a conventional manufacturing method generally called a paste-type electrode is to pulverize a hydrogen-absorbing alloy into a few tens of μm, form a paste using a binder such as polyvinyl alcohol, and form a punching metal or nickel foam. By applying the paste to such a support, the paste was prevented from falling off. However, when the binder, the support, and the separator are used as a battery, they do not contribute to hydrogen storage and release, so that the filling amount of the hydrogen storage alloy in a fixed volume (battery) is small. On the other hand, a method of improving the strength against cracking by crushing the hydrogen storage alloy and directly sintering it to form an electrode has been considered.
【０００４】しかし、直接焼結させただけの焼結体は結
着剤や支持体が必要でないため、合金の充填量は向上す
るが、合金の充填密度を一般に望ましいとされている多
孔率２０〜４０％にするためには高温度における熱処理
が必要となる。そのような高温を合金に加えると、合金
中の金属の組織的な変動が大きく起こり水素吸蔵特性を
大きく低下させることが問題化されている。そのため、
合金粉末表面の全体または一部を他の金属例えばニッケ
ル等で被覆したり、他の金属粉等の焼結助剤を添加する
ことにより焼結温度を低下させることが提案されてい
た。しかし、この場合、電極の製造工程の複雑化、コス
トの上昇、合金被覆部分及び助剤が水素吸蔵放出に預か
らないため好ましくなかった。[0004] However, a sintered body which is simply sintered directly does not require a binder or a support, so that the filling amount of the alloy is improved, but the packing density of the alloy is preferably 20%. Heat treatment at a high temperature is required in order to make it up to 40%. When such a high temperature is applied to the alloy, the systematic fluctuation of the metal in the alloy greatly occurs, and it has been problematic that the hydrogen storage characteristics are greatly reduced. for that reason,
It has been proposed to coat the whole or a part of the surface of the alloy powder with another metal, such as nickel, or to lower the sintering temperature by adding a sintering aid such as another metal powder. However, in this case, the manufacturing process of the electrode is complicated, the cost is increased, and the alloy-coated portion and the auxiliary agent are not included in the hydrogen storage and release, which is not preferable.
【０００５】[0005]
【発明が解決しようとする課題】このように水素吸蔵合
金に対し他の金属の被覆や焼結助剤の添加等の対策がと
られて、さらに合金を微粉化すれば焼結温度は低下させ
ることができるが、主に希土類金属を多く含む合金（金
属間化合物）は微粉化により合金表面積は大きくなり、
非常に酸化されやすくなる。吸着された酸素は、焼結中
に合金と反応し、水素の吸蔵放出に預からない酸化物を
生成することや、該酸化物は不導体であるため焼結体の
電気抵抗が増大し、電池としての性能を低下させてい
た。また、吸着する酸素量を低減させるため低酸素雰囲
気で粉砕を行っても、有機溶剤中での粉砕は炭素汚染を
避けられず、同様に焼結後の合金の水素吸蔵放出の容量
を低下させたいた。さらに、従来から使われている合金
すなわち機械式粉砕による合金粉末は、特に粒度分布が
非常に大きくなり、１μｍ以下の微粉や粒子径の大きい
粉末が多数あり、金属組織のバラツキがあり、負極を作
製した場合に容量を低下させる等の悪影響を及ぼしてい
た。As described above, countermeasures such as coating of another metal and addition of a sintering aid to the hydrogen storage alloy are taken, and the sintering temperature is lowered by further pulverizing the alloy. However, alloys containing a large amount of rare earth metals (intermetallic compounds) mainly have a large alloy surface area due to pulverization,
Very easily oxidized. The adsorbed oxygen reacts with the alloy during sintering to form an oxide that is not included in the occlusion and release of hydrogen, and the oxide is a non-conductor, so that the electrical resistance of the sintered body increases, The performance as a battery was degraded. In addition, even if grinding is performed in a low oxygen atmosphere to reduce the amount of adsorbed oxygen, grinding in an organic solvent inevitably causes carbon contamination, and similarly reduces the capacity of hydrogen absorption and release of the sintered alloy. Hit. In addition, the conventionally used alloys, that is, alloy powders obtained by mechanical pulverization, particularly have a very large particle size distribution, a large number of fine powders of 1 μm or less and powders having a large particle diameter, and there are variations in the metallographic structure. In the case of manufacturing, there was an adverse effect such as lowering the capacity.
【０００６】[0006]
【課題を解決するための手段】本発明は、上記課題を解
決するために鋭意研究されたものであり、水素吸蔵合金
の酸化及び炭素汚染を防止することを目的としており、
水素吸蔵合金塊を不活性ガス雰囲気下で粉砕すると同時
に分級させ、成形、焼結させた水素吸蔵燒結材料、およ
び該水素吸蔵燒結材料を用いたアルカリ蓄電池用負極を
提供する。DISCLOSURE OF THE INVENTION The present invention has been intensively studied in order to solve the above problems, and has as its object to prevent oxidation of a hydrogen storage alloy and carbon contamination.
Provided are a hydrogen storage sintered material obtained by pulverizing and classifying a hydrogen storage alloy lump in an inert gas atmosphere while simultaneously classifying and sintering, and a negative electrode for an alkaline storage battery using the hydrogen storage sintered material.
【０００７】[0007]
【発明の実施の形態】本発明に係る水素吸蔵燒結材料
は、水素吸蔵合金を焼結させて得られるものである。使
用できる水素吸蔵合金塊の組成および製造方法として
は、特に限定するものではなく、ＡＢn （ｎは、１〜６
であらわされる数である。）で表される構造を有する水
素吸蔵合金であればよい。特に本発明では、ＡＢ5 系の
水素吸蔵合金組成のものが電池寿命の点で好ましい。具
体的には、一般式 Ｒ（Ｎｉ）a （Ｍｎ）b （Ａｌ）c
（Ｃｏ）d （Ｍ）eで表される水素吸蔵合金である。式
中、Ｒは、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄのうちいずれか単
独、またはＬａと一以上のＹ（イットリウム）を含む希
土類元素との混合物であり、特にＬａ以外に用いられる
希土類元素は、Ｃｅ、Ｐｒ、Ｎｄから一種以上用い、Ｒ
中にＬａを２０重量％以上含むことが好ましい。Ｍは、
Ｓｉ、Ｆｅ、Ｐｂ、Ｔｉ、Ｃａ、Ｍｇ、Ｃｕ、Ｉｎ、Ｚ
ｎ、Ｃｒ、ＭｏおよびＺｒからなる一群から選ばれた少
なくとも一種の元素である。また、ａ、ｂ、ｃ、ｄ、ｅ
は、Ｒを原子比１．０とした場合に、原子比を表す係数
であり、以下の関係を満たす数である。 １．８≦ａ≦６．０ ０≦ｂ≦０．６ ０≦ｃ≦０．４ ０≦ｄ≦１．０ ０≦ｅ≦０．２ ４．０≦ａ＋ｂ＋ｃ＋ｄ＋ｅ≦６．０BEST MODE FOR CARRYING OUT THE INVENTION The hydrogen storage sintered material according to the present invention is obtained by sintering a hydrogen storage alloy. The composition and production method of the hydrogen storage alloy lump that can be used are not particularly limited, and AB n (n is 1 to 6)
It is a number represented by Any hydrogen storage alloy having the structure represented by the formula (1) may be used. Particularly in the present invention are those of the hydrogen storage alloy composition of AB 5 type is preferred in terms of battery life. Specifically, the general formula R (Ni) a (Mn) b (Al) c
It is a hydrogen storage alloy represented by (Co) d (M) e . In the formula, R is any one of La, Ce, Pr, and Nd, or a mixture of La and one or more rare earth elements containing Y (yttrium). In particular, rare earth elements used other than La are Ce. , Pr, Nd
It is preferable to contain La in an amount of 20% by weight or more. M is
Si, Fe, Pb, Ti, Ca, Mg, Cu, In, Z
It is at least one element selected from the group consisting of n, Cr, Mo and Zr. A, b, c, d, e
Is a coefficient that represents the atomic ratio when R is 1.0, and is a number that satisfies the following relationship. 1.8 ≦ a ≦ 6.0 0 ≦ b ≦ 0.6 0 ≦ c ≦ 0.4 0 ≦ d ≦ 1.0 0 ≦ e ≦ 0.2 4.0 ≦ a + b + c + d + e ≦ 6.0
【０００８】本発明では、上記組成からなる水素吸蔵合
金を、アーク溶解炉、高周波溶解炉等を用い、アルゴ
ン、ヘリウム等の不活性ガス雰囲気下で、１３００〜１
６００℃で溶解させ溶湯化し、除冷させ、水素吸蔵合金
塊を得る。さらに、合金組成の偏析を防止するため、合
金塊を８００〜１１００℃で加熱処理する。In the present invention, a hydrogen storage alloy having the above-mentioned composition is prepared in an arc melting furnace, a high-frequency melting furnace or the like under an inert gas atmosphere such as argon, helium or the like at 1300-1.
It is melted at 600 ° C. to form a molten metal, and then cooled to obtain a hydrogen storage alloy lump. Further, in order to prevent segregation of the alloy composition, the alloy ingot is heat-treated at 800 to 1100 ° C.
【０００９】このようにして得られた水素吸蔵合金を、
本発明では、サイクロン等を具備したジェット粉砕機、
アトライターを用いて、平均粒子径２〜２０μｍ、好ま
しくは５〜１０μｍの粒度範囲に同時に分級粉砕する。
さらに粒子径を１〜４０μｍ以内に粒度を分布させるこ
とが好ましい。平均粒子径を５μｍ未満にすると合金の
酸化の影響が大きくなり、劣化する。２０μｍを超える
と合金粒子が粗大化しており、活性化の遅れを生じるこ
とや、焼結温度において１２００℃以上の高温が必要と
なり好ましくない。[0009] The hydrogen storage alloy thus obtained is
In the present invention, a jet crusher equipped with a cyclone or the like,
Using an attritor, the particles are simultaneously classified and pulverized into a particle size range of 2 to 20 μm, preferably 5 to 10 μm.
Further, the particle size is preferably distributed within a range of 1 to 40 μm. If the average particle size is less than 5 μm, the influence of the oxidation of the alloy becomes large and the alloy deteriorates. If it exceeds 20 μm, the alloy particles become coarse, which causes a delay in activation and requires a high temperature of 1200 ° C. or higher in sintering temperature, which is not preferable.
【００１０】本発明では、水素吸蔵合金塊を窒素、アル
ゴン等の不活性ガス、特に窒素の高速気流で、ジェット
粉砕機またはアトライターを用いた粉砕方法をすること
により、下記粒度分布に水素吸蔵合金粉末を同時に分級
することができる。In the present invention, a hydrogen storage alloy lump is subjected to a pulverization method using a jet pulverizer or an attritor with a high-speed gas stream of an inert gas such as nitrogen or argon, particularly nitrogen, so that the hydrogen storage alloy has the following particle size distribution. The alloy powder can be classified at the same time.
【数２】 ［式中、Ｘは、合金粉末の粒度分布の標準偏差値（μ
ｍ）を表し、Ｙは、合金粉末の平均粒子径（μｍ）を表
す。］ 本発明ではサイクロン、ターボクラシファイヤー等の分
級機を粉砕機中に具備させ、粉砕と同時に粒度を分級し
ながら、粉砕粒度のバラツキをコントロールする。な
お、粉砕と同時に分級を行うことが、省スペース及び効
率等の点で好ましいが、粉砕と分級を別個に行う態様で
あってもよい。(Equation 2) [In the formula, X is a standard deviation value (μ
m), and Y represents the average particle diameter (μm) of the alloy powder. In the present invention, a classifier such as a cyclone, a turbo classifier or the like is provided in the pulverizer to control the variation in the pulverized particle size while classifying the particle size simultaneously with the pulverization. Note that it is preferable to perform classification at the same time as pulverization in terms of space saving and efficiency, but an embodiment in which pulverization and classification are performed separately may be employed.
【００１１】このような粉砕と同時に分級された水素吸
蔵合金粉末を用いることにより、焼結したのちでも、合
金中の酸素量を合金重量に対し０．３重量％以下に低減
させることができ、さらに有機溶剤中での粉砕を用いな
いので炭素汚染（炭素濃度０．０１重量％以下）を防止
できる。合金中の酸素含有量を低減できるのは、ジェッ
トミル、アトライターにより、粒度分布を鋭角にでき、
また分級により比表面積の大きい微細な粒子を削除でき
たことによる。By using the hydrogen storage alloy powder classified at the same time as the pulverization, the oxygen content in the alloy can be reduced to 0.3% by weight or less based on the weight of the alloy even after sintering. Further, since no pulverization in an organic solvent is used, carbon contamination (carbon concentration of 0.01% by weight or less) can be prevented. The oxygen content in the alloy can be reduced because the jet mill and attritor can sharpen the particle size distribution,
In addition, fine particles having a large specific surface area could be removed by classification.
【００１２】上記式（１）における粒度分布を６０％以
上の粒度分布の合金粉末を電極として用いた場合、粒径
が非常に細かい粒を多く含むことになるが、粒径が細か
いほど低温で焼結が進むため、焼結体の組織において部
分的なバラツキを生じ、電気化学的に必要な連続した空
孔を閉塞させたり、成形体の内部でも過度に焼結された
部分と未焼結部分が生じ、電極としての強度が低下す
る。また、上記式（１）における粒度分布を６０％以上
の粒度分布の合金粉末を電極として用いた場合、粒径が
大きい粗大な粒を多く含むことにもなり、その粗大な粒
子の活性化の遅れは、初期容量の低下を生ずる傾向があ
る。振動ミル等の機械式粉砕を用いた場合には、微粉が
多く得られ、（１）式における粒度分布が６５％以上に
なってしまい、上記欠点を有する電極が得られる。When an alloy powder having a particle size distribution of 60% or more in the above formula (1) is used as an electrode, many particles having a very small particle size are contained. Due to the progress of sintering, partial variations occur in the structure of the sintered body, closing continuous pores required electrochemically, and unsintered parts inside the molded body with excessively sintered parts Some portions are formed, and the strength as an electrode is reduced. In addition, when an alloy powder having a particle size distribution of 60% or more in the above formula (1) is used as an electrode, many coarse particles having a large particle size are included, and the activation of the coarse particles is increased. The delay tends to cause a decrease in the initial capacity. When mechanical pulverization such as a vibration mill is used, a large amount of fine powder is obtained, and the particle size distribution in the formula (1) becomes 65% or more, so that an electrode having the above-mentioned disadvantage is obtained.
【００１３】本発明では、水素吸蔵合金塊を、窒素、ア
ルゴン、ヘリウム等の不活性ガス下で粉砕するのである
が、特に窒素ガス雰囲気下としたことは、粉砕時におけ
る粉末の昇温を防止でき、合金組成への酸素などの不純
物の混入を抑制するためであり、厳密に不活性雰囲気下
に限らず、この目的を達成できる態様であればよい。In the present invention, the hydrogen storage alloy lump is pulverized under an inert gas such as nitrogen, argon, helium, etc. In particular, the use of a nitrogen gas atmosphere prevents the powder from rising during the pulverization. This is to suppress the entry of impurities such as oxygen into the alloy composition, and is not limited to a strictly inert atmosphere, but may be any mode that can achieve this purpose.
【００１４】本発明では、このような粒度分布にした合
金粉末を直接焼結させることにより、集電支持体を必須
とせずに電極に用いることができる。したがって、本発
明は合金粉末を直接焼結することができ、充填量の高い
所望の形状の焼結体が得られることができる。該粒度分
布を有する合金粉末を鋳型に充填し加熱処理することで
焼結体を得る。合金粉末を焼結させる温度は６００〜１
１００℃、好ましくは９００〜１１００℃である。加熱
温度を６００℃以下にすると、焼結が起こらず合金同士
の結合反応を行うことができない。また、１１００℃を
超えると、合金の金属組成の偏析が起こり均質な焼結電
極が得られない。この場合、焼結雰囲気を、１０-4〜１
０-5torrの真空下、非酸化性雰囲気、特にアルゴン、ヘ
リウム等の不活性ガス雰囲気下で処理することが好まし
い。In the present invention, by directly sintering the alloy powder having such a particle size distribution, the current collector can be used for the electrode without making it essential. Therefore, according to the present invention, the alloy powder can be directly sintered, and a sintered body having a desired shape and a high filling amount can be obtained. A sintered body is obtained by filling a mold with the alloy powder having the particle size distribution and performing heat treatment. The temperature for sintering the alloy powder is 600 to 1
The temperature is 100 ° C, preferably 900 to 1100 ° C. When the heating temperature is set to 600 ° C. or lower, sintering does not occur and a bonding reaction between alloys cannot be performed. On the other hand, when the temperature exceeds 1100 ° C., segregation of the metal composition of the alloy occurs, and a homogeneous sintered electrode cannot be obtained. In this case, the sintering atmosphere is 10 -4 to 1
The treatment is preferably performed under a non-oxidizing atmosphere under a vacuum of 0 -5 torr, particularly under an inert gas atmosphere such as argon or helium.
【００１５】このようにして得られた焼結体は、多孔質
焼結体になっており、電極として好ましい多孔率２０〜
４０％を気孔を有している。また、粒度分布のバラツキ
幅が狭く、平均的に焼結することができることで、強度
が向上し、電池とした場合のサイクル寿命の向上も期待
できる。この焼結体に直接リード線をとりつけ負極と
し、その外側にセパレータ、水酸化ニッケル正極とを構
成させ苛性カリ等の電解液を注入し、アルカリ蓄電池を
得ることができる。本発明では、水素吸蔵合金のみを焼
結し、電極として構成しているため、従来のペースト式
電極による蓄電池と比較し、どれも単位体積当りの水素
吸蔵合金の充填密度を大幅に改善することができるた
め、装置の小型かもしくは高容量化と合わせて電極の製
造方法が容易に安価なアルカリ蓄電池を提供することが
できる。本発明の原理は、密閉式電池を作製したとして
も、同様に効果が期待できる。[0015] The sintered body thus obtained is a porous sintered body and has a porosity of 20 to 20 which is preferable as an electrode.
40% have pores. Further, since the dispersion width of the particle size distribution is narrow and sintering can be performed on average, strength is improved, and improvement in cycle life in the case of a battery can be expected. A lead wire is directly attached to the sintered body to form a negative electrode, a separator and a nickel hydroxide positive electrode are formed outside the negative electrode, and an electrolytic solution such as caustic potash is injected to obtain an alkaline storage battery. In the present invention, since only the hydrogen storage alloy is sintered and configured as an electrode, compared with a conventional storage battery using a paste-type electrode, any of the above-described methods significantly improves the packing density of the hydrogen storage alloy per unit volume. Therefore, it is possible to provide an inexpensive alkaline storage battery in which the manufacturing method of the electrodes can be easily performed along with the reduction in the size or the increase in the capacity of the device. The principle of the present invention can be expected to have the same effect even when a sealed battery is manufactured.
【００１６】[0016]
【実施例】（実施例１〜２、比較例１〜２）市販のＭｍ
（Ｌａ３５重量％、Ｃｅ５０％、Ｐｒ５％、Ｎｄ１０
％）原子比１に対し、Ｎｉを３．６５、Ｃｏを０．７
５、Ａｌを０．３、Ｍｎを０．３となるように秤量し、
アーク溶解炉にて溶解し、ＣａＣｕ5 構造の合金塊を得
た。得られた水素吸蔵合金塊をサイクロンを具備したジ
ェット粉砕機で窒素ガス雰囲気のもと、酸素濃度２．５
％以下の雰囲気にて平均粒度が７μｍになるように粉砕
し、該合金粒子の粒度分布における標準偏差値を４．９
μｍ、４．３μｍ、４．１μｍ、３．５μｍの粉末を得
た。この時の標準偏差を平均粒径で割った値はそれぞれ
約７０．０％、６１．４％、５８．６％、５０．０％に
コントロールした。これらの合金粉末を加圧成形し、そ
の後１０-4torrの真空雰囲気において９５０℃で加熱処
理をし水素吸蔵合金の焼結体Ｍ１〜Ｍ４を得、気孔率３
０％の焼結体を得た。燒結−赤外線吸収法により燒結体
（合金）を測定したところ、炭素汚染は見られなかっ
た。 なお、気孔率は、（気孔率）＝｛１−（焼結密度）／
（理論密度）｝・１００ 焼結密度は、JIS Z 2505に準拠して求めた。EXAMPLES (Examples 1-2, Comparative Examples 1-2) Commercially available Mm
(La 35% by weight, Ce 50%, Pr 5%, Nd10
%) For an atomic ratio of 1, Ni is 3.65 and Co is 0.7.
5, Weigh Al to 0.3, Mn to 0.3,
Melting was performed in an arc melting furnace to obtain an alloy lump having a CaCu 5 structure. The obtained hydrogen-absorbing alloy lump was subjected to a jet pulverizer equipped with a cyclone under a nitrogen gas atmosphere under an oxygen concentration of 2.5.
% Of the alloy particles in an atmosphere having a particle size distribution of 4.9% or less.
μm, 4.3 μm, 4.1 μm, and 3.5 μm were obtained. The values obtained by dividing the standard deviation at this time by the average particle size were controlled to about 70.0%, 61.4%, 58.6%, and 50.0%, respectively. These alloy powders are pressed and then heat-treated at 950 ° C. in a vacuum atmosphere of 10 −4 torr to obtain sintered bodies M1 to M4 of a hydrogen storage alloy, and have a porosity of 3
A 0% sintered body was obtained. When the sintered body (alloy) was measured by the sintering-infrared absorption method, no carbon contamination was observed. The porosity is (porosity) = ｛1− (sintered density) /
(Theoretical density)｝ · 100 The sintered density was determined in accordance with JIS Z 2505.
【００１７】表１は、焼結体Ｍ１〜Ｍ４を負極とし、公
知の水酸化ニッケルを用い、負極規制の開放型アルカリ
蓄電池を作製し、２０℃の一定条件下で０．３Ｃで５時
間充電を行い、休止時間１時間経過後、０．２Ｃで０．
８Ｖまでの放電を繰り返し、充放電サイクル試験を行っ
た結果であり、１サイクル目の容量を初期容量、最高容
量及び１００サイクル目において最高容量に対し何％容
量が低下したかを示す低下比を表に表した。Table 1 shows that an open-type alkaline storage battery with a negative electrode regulation was prepared by using a known nickel hydroxide with the sintered bodies M1 to M4 as negative electrodes, and charged at 0.3 C for 5 hours under a constant condition of 20 ° C. , And after a lapse of one hour, the pressure is reduced to 0.2 at 0.2C.
It is a result of conducting a charge / discharge cycle test by repeating discharge up to 8 V. The first cycle capacity is the initial capacity, the maximum capacity, and the reduction ratio indicating the percentage of the capacity decreased with respect to the maximum capacity at the 100th cycle. It is shown in the table.
【表１】 [Table 1]
【００１８】表１より、本発明に基づき、粒度分布にお
ける標準偏差を平均粒径で割った値が６０％以下に作製
されたＭ３〜Ｍ４（実施例１、２）は、本発明の範囲外
であるＭ１〜Ｍ２（比較例１、２）に比べ、初期容量に
優れている。これは、Ｍ１、Ｍ２に粗大な粒子を多く含
み、その粗大な粒子の活性化の遅れや微細な粒子による
細孔の閉塞が原因と考えられる。Ｍ３、Ｍ４は、最大容
量においてもすぐれている。Ｍ１、Ｍ２には粗大な粒子
のほかに微細な粒子も多く含まれているので、単位重量
当りの表面積が大きいため、焼結時酸化により劣化した
ものであると考えられる。また、同様にサイクル寿命に
おいても粒度分布のバラツキ幅が狭く、平均的に焼結す
ることができることで、強度が向上したことによる。本
発明の原理は、密閉式電池を作製したとしても、同様に
効果が期待できる。From Table 1, according to the present invention, M3 to M4 (Examples 1 and 2) in which the value obtained by dividing the standard deviation in the particle size distribution by the average particle size was 60% or less were out of the scope of the present invention. M1 to M2 (Comparative Examples 1 and 2). This is considered to be due to the fact that M1 and M2 contain many coarse particles, and the activation of the coarse particles is delayed and the pores are blocked by fine particles. M3 and M4 are also excellent in the maximum capacity. Since M1 and M2 contain many fine particles in addition to coarse particles, they have a large surface area per unit weight, and are considered to have been deteriorated by oxidation during sintering. Similarly, the variation in particle size distribution in the cycle life is narrow, and sintering can be performed on average, thereby improving strength. The principle of the present invention can be expected to have the same effect even when a sealed battery is manufactured.
【００１９】[0019]
【発明の効果】このような粉砕と同時に分級された水素
吸蔵合金粉末を用いることにより、焼結したのちでも、
合金中の酸素量を合金重量に対し０．３重量％以下に低
減させることができ、さらに有機溶剤中での粉砕を用い
ないので炭素汚染（炭素濃度０．０１重量％以下）を防
止できる。また、分級により微細な粒子や粗大な粒子を
削除した粒度分布を有する合金粉末を直接焼結させるこ
とにより、集電支持体を必須とせずに電極に用いること
ができる。従って、従来のペースト式電極による蓄電池
と比較し、どれも単位体積当りの水素吸蔵合金の充填密
度を大幅に改善することができるため、装置の小型かも
しくは高容量化と合わせて電極の製造方法が容易に安価
なアルカリ蓄電池を提供することができる。また、本発
明における燒結体は、アルカリ蓄電池用負極だけでな
く、水素吸蔵システム等にも応用できるものである。さ
らに、分級の効果として、粒度分布のバラツキ幅が狭い
水素吸蔵合金粉末が得られるので、平均的に焼結するこ
とができる。従って、燒結体の強度が向上し、電池とし
た場合のサイクル寿命の向上も期待できる。By using the hydrogen storage alloy powder classified at the same time as the pulverization, even after sintering,
The amount of oxygen in the alloy can be reduced to 0.3% by weight or less based on the weight of the alloy, and further, since no pulverization in an organic solvent is used, carbon contamination (carbon concentration of 0.01% by weight or less) can be prevented. Further, by directly sintering an alloy powder having a particle size distribution from which fine particles and coarse particles have been removed by classification, a current collecting support can be used without being essential. Therefore, as compared with the conventional storage battery using the paste-type electrode, the packing density of the hydrogen storage alloy per unit volume can be greatly improved. Can easily provide an inexpensive alkaline storage battery. Further, the sintered body according to the present invention can be applied not only to a negative electrode for an alkaline storage battery, but also to a hydrogen storage system and the like. Furthermore, as an effect of classification, a hydrogen storage alloy powder having a narrow variation in particle size distribution can be obtained, so that sintering can be performed on average. Therefore, the strength of the sintered body is improved, and the cycle life of a battery can be expected to be improved.
Claims (4)
粉砕すると同時に分級させ、水素吸蔵合金粉末を得、成
形、焼結させた水素吸蔵燒結材料。1. A hydrogen storage and sintering material obtained by pulverizing a hydrogen storage alloy lump in an inert gas atmosphere and classifying it at the same time to obtain a hydrogen storage alloy powder, molding and sintering.
ｍ）を表し、Ｙは、合金粉末の平均粒子径（μｍ）を表
す。］の範囲の分級である請求項１に記載の水素吸蔵燒
結材料。2. The classification according to the formula (1) [In the formula, X is a standard deviation value (μ
m), and Y represents the average particle diameter (μm) of the alloy powder. 2. The hydrogen storage and sintering material according to claim 1, wherein the classification is within the range of [1].
砕するものである請求項１または請求項２に記載の水素
吸蔵燒結材料。3. The sintered material according to claim 1, wherein the pulverization is performed to pulverize the particles to an average particle size of 2 to 20 μm.
蔵燒結材料を用いたアルカリ蓄電池用負極。4. A negative electrode for an alkaline storage battery using the hydrogen storage and sintering material according to claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10154359A JPH11350001A (en) | 1998-06-03 | 1998-06-03 | Hydrogen storage sintering material and negative electrode for alkaline storage battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10154359A JPH11350001A (en) | 1998-06-03 | 1998-06-03 | Hydrogen storage sintering material and negative electrode for alkaline storage battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11350001A true JPH11350001A (en) | 1999-12-21 |
Family
ID=15582442
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10154359A Pending JPH11350001A (en) | 1998-06-03 | 1998-06-03 | Hydrogen storage sintering material and negative electrode for alkaline storage battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH11350001A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007066675A (en) * | 2005-08-31 | 2007-03-15 | Sanyo Electric Co Ltd | Manufacturing method of hydrogen storage alloy for alkaline storage battery, and hydrogen storage alloy for alkaline storage battery, and alkaline storage battery |
-
1998
- 1998-06-03 JP JP10154359A patent/JPH11350001A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007066675A (en) * | 2005-08-31 | 2007-03-15 | Sanyo Electric Co Ltd | Manufacturing method of hydrogen storage alloy for alkaline storage battery, and hydrogen storage alloy for alkaline storage battery, and alkaline storage battery |
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