JPH11140501A - Production of hydrogen storage alloy powder - Google Patents
Production of hydrogen storage alloy powderInfo
- Publication number
- JPH11140501A JPH11140501A JP9313064A JP31306497A JPH11140501A JP H11140501 A JPH11140501 A JP H11140501A JP 9313064 A JP9313064 A JP 9313064A JP 31306497 A JP31306497 A JP 31306497A JP H11140501 A JPH11140501 A JP H11140501A
- Authority
- JP
- Japan
- Prior art keywords
- powder
- hydrogen storage
- oxygen
- storage alloy
- state
- 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- Withdrawn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
- 239000000843 powder Substances 0.000 title claims abstract description 62
- 239000001257 hydrogen Substances 0.000 title claims abstract description 32
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 32
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 30
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 23
- 239000000956 alloy Substances 0.000 title claims abstract description 23
- 238000003860 storage Methods 0.000 title claims abstract description 22
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims abstract description 24
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000001301 oxygen Substances 0.000 claims abstract description 16
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 16
- 229910052786 argon Inorganic materials 0.000 claims abstract description 12
- 238000000034 method Methods 0.000 claims abstract description 12
- 238000004381 surface treatment Methods 0.000 claims abstract description 10
- 239000002253 acid Substances 0.000 claims abstract description 8
- 238000009689 gas atomisation Methods 0.000 claims abstract description 8
- 238000003756 stirring Methods 0.000 claims abstract description 8
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 19
- 239000007789 gas Substances 0.000 claims description 11
- 238000006386 neutralization reaction Methods 0.000 claims description 9
- 229910052759 nickel Inorganic materials 0.000 claims description 8
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 6
- 229910001882 dioxygen Inorganic materials 0.000 claims description 6
- 229910001122 Mischmetal Inorganic materials 0.000 claims description 4
- 238000010306 acid treatment Methods 0.000 abstract description 11
- 238000004090 dissolution Methods 0.000 abstract description 3
- 238000010438 heat treatment Methods 0.000 abstract description 3
- 230000007935 neutral effect Effects 0.000 abstract 2
- 239000000243 solution Substances 0.000 description 9
- 239000000463 material Substances 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 239000002245 particle Substances 0.000 description 6
- 238000010521 absorption reaction Methods 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 238000010298 pulverizing process Methods 0.000 description 4
- 230000004913 activation Effects 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 238000005266 casting Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000001747 exhibiting effect Effects 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 239000007773 negative electrode material Substances 0.000 description 2
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910000990 Ni alloy Inorganic materials 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- OJIJEKBXJYRIBZ-UHFFFAOYSA-N cadmium nickel Chemical compound [Ni].[Cd] OJIJEKBXJYRIBZ-UHFFFAOYSA-N 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 230000000415 inactivating effect Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 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
- 238000012544 monitoring process Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 229910001404 rare earth metal oxide Inorganic materials 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000012798 spherical particle Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel 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
- Battery Electrode And Active Subsutance (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Powder Metallurgy (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、水素吸蔵合金粉
末、特にニッケル水素電池用の負極材料用のＡＢ5型水
素吸蔵合金粉末の製造方法に関するものである。The present invention relates to a hydrogen absorbing alloy powder, and more particularly to a method of manufacturing the AB 5 type hydrogen-absorbing alloy powder for the negative electrode material for a nickel-hydrogen battery.
【０００２】[0002]
【従来の技術】近年、ニッケルカドミウム電池に代わる
二次電池としてニッケル水素電池が注目され、そのため
の水素吸蔵合金粉末が研究されているが、中でもＡＢ5
型水素吸蔵合金粉末は電池用の負極材として優れた特性
を備えて、利用されている。これは、例えばＣｅ５０
％、Ｌａ２５％，Ｎｄ１５％，残りＰｒなどからなるミ
ッシュメタルＭｍと、例えばＭｎ，Ａｌ，Ｃｏ等を含む
ニッケル合金とを混合溶融したもので、例えば、Ｍｍ
1.0 Ｎｉ（５−ｘ−ｙ−ｚ）ＭｎｘＡｌｙＣｏｚのよう
な型の金属間化合物である。従来はこれを鋳造材の粉砕
や回転ドラムに接触させる急冷凝固薄帯の粉砕、ガスア
トマイズなどの諸手法によって粉末化しているのが実状
である。In recent years, nickel-hydrogen battery is attracting attention as a secondary battery in place of nickel-cadmium battery, a hydrogen absorbing alloy powder therefor have been studied, among others AB 5
Hydrogen storage alloy powders are used with excellent characteristics as negative electrode materials for batteries. This is, for example, Ce50
%, La 25%, Nd 15%, remaining Pr, etc., and a mixture of a misch metal Mm and a nickel alloy containing, for example, Mn, Al, Co or the like.
1.0 is an intermetallic compound of the type such as Ni (5-xyz) MnxAlyCoz. Heretofore, in practice, the powder has been powdered by various methods such as pulverization of a cast material, pulverization of a rapidly solidified thin ribbon brought into contact with a rotating drum, and gas atomization.
【０００３】[0003]
【発明が解決しようとする課題】上述の諸粉末化方法の
うち、鋳造材を粉砕する方法は材料の偏析などにより各
粉末粒子の組成が均一にならず、二次電池に用いた場合
の性能はガスアトマイズ法や急冷凝固薄帯の粉砕などで
得た粉末に劣る。そして、ガスアトマイズ法によって得
た粉末は粒子の形状が球状であるため、鋳造材や急冷薄
帯を粉砕して得た粉末に比べて電池電極に組み入れた場
合の充填密度が優れ、同じ水素吸蔵特性を持つ粉末を電
極に使用した場合でも、電極のエネルギー密度を高くす
ることができ、容量の大きい電池の製造が可能である。Among the various powdering methods described above, the method of pulverizing a cast material does not have a uniform composition of each powder particle due to segregation of the material and the like, and the performance when used in a secondary battery is reduced. Is inferior to powders obtained by gas atomization or crushing of rapidly solidified ribbons. Since the powder obtained by the gas atomization method has a spherical particle shape, the packing density when incorporated into a battery electrode is superior to that obtained by pulverizing a cast material or a quenched ribbon, and has the same hydrogen storage characteristics. Even when a powder having the following is used for the electrode, the energy density of the electrode can be increased, and a battery with a large capacity can be manufactured.
【０００４】水素吸蔵合金粉末を二次電池に使用する場
合に要求される性能は、水素の吸蔵量が大きいことと、
水素の吸収・放出が迅速なこと、及び吸収・放出の反復
による水素吸蔵量の低下が少ないことである。水素吸蔵
量の大小は電池の容量に関係し、吸収・放出の速度は電
池の放電効率や充電の際の電池の内圧の上昇に関係し、
水素吸蔵量の低下は二次電池としての寿命に関係する。[0004] When the hydrogen storage alloy powder is used for a secondary battery, the performance required is that the hydrogen storage amount is large,
The quick absorption and release of hydrogen and the decrease in the amount of hydrogen storage due to the repeated absorption and release are small. The amount of hydrogen storage is related to the capacity of the battery, and the rate of absorption and release is related to the discharge efficiency of the battery and the increase in the internal pressure of the battery during charging.
The decrease in the hydrogen storage capacity is related to the life of the secondary battery.
【０００５】上述の水素の吸蔵量の大きさ及び吸収・放
出の速さは、合金粉末の表面の酸化物層に大きく影響さ
れる。ところが、上述の水素吸蔵合金粉末は希土類元素
を多量に含むために酸化しやすく、アルゴンガスアトマ
イズにより粉末化した場合でも、雰囲気中のわずかな酸
素分圧のために表面に酸化層ができ、その酸化層は鋳造
材を粉砕して得た粉末に比べて厚い場合が多い。[0005] The magnitude of the amount of hydrogen absorbed and the speed of absorption and desorption are greatly affected by the oxide layer on the surface of the alloy powder. However, the above-mentioned hydrogen storage alloy powder is liable to be oxidized because it contains a large amount of rare earth elements, and even when powdered by argon gas atomization, an oxidized layer is formed on the surface due to a slight oxygen partial pressure in the atmosphere. The layer is often thicker than the powder obtained by grinding the cast material.
【０００６】このように粒子の大部分の表面が酸化層で
覆われている粉末は、粉末が水素吸蔵できる状態にする
活性化工程が必要で、あるいは粉末を活性化せずにその
まま用いて電池を作製した場合は、長時間かけて充放電
をくり返し、電池の容量を、高めることが必要となり、
生産性を著しく妨げる。電池の特性をより向上させると
共に、生産性を上げる方法として、例えば特開平６−８
８１５号公報のような、粉末を酸処理して粒子表面の酸
化層を除くことが提案されている。[0006] In the case of such a powder in which the surface of most of the particles is covered with an oxide layer, an activation step for bringing the powder into a state capable of absorbing hydrogen is required, or the powder is used as it is without activating the battery. , It is necessary to repeatedly charge and discharge over a long period of time to increase the capacity of the battery,
Significantly hinders productivity. As a method of further improving the characteristics of the battery and increasing the productivity, for example, JP-A-6-8
As disclosed in Japanese Patent Publication No. 815, it has been proposed to treat a powder with an acid to remove an oxide layer on the particle surface.
【０００７】上述の水素吸蔵量の低下は、充放電のくり
返しによって粉末粒子が必要以上に細かく破砕されるこ
とが原因である。このような破砕は、粒子内部のミクロ
的な合金組成の不均一や、鋳造時の残留歪などが原因と
なって、水素を吸収・放出する際の体積の膨張・収縮が
一様に行われないことが一因となっている。そして破砕
面から酸化が進行して、水素吸蔵能力が次第に失われて
いくのである。[0007] The decrease in the amount of hydrogen occlusion described above is due to the fact that powder particles are crushed more than necessary due to repeated charging and discharging. In such crushing, the expansion and contraction of the volume when absorbing and releasing hydrogen is performed uniformly due to the unevenness of the microscopic alloy composition inside the particles and the residual strain during casting. This is partly due to the absence. Then, oxidation proceeds from the crushed surface, and the hydrogen storage capacity is gradually lost.
【０００８】従って、電池の寿命を延ばすためには、粉
末粒子の合金組成がミクロ的に均一で、かつ歪が残存し
ていないことが条件になる。そのために、従来では鋳造
・粉砕工程の途中に高温で長時間熱処理することが行わ
れている。ガスアトマイズ粉末の場合は鋳造材に比べ
て、合金組成がかなり均一で、歪の残存量も少なく、従
って、熱処理も鋳造材の場合よりも低い温度、短い時間
で良好な組織の粉末になる。上述のような理由によっ
て、現在ではガスアトマイズによって得た合金粉末を熱
処理し、その粉末を熱処理したものが電池用として最適
な粉末であると考えられる。Therefore, in order to extend the life of the battery, it is a condition that the alloy composition of the powder particles is microscopically uniform and no strain remains. Therefore, conventionally, a long-time heat treatment is performed at a high temperature during the casting / crushing process. In the case of gas atomized powder, the alloy composition is considerably uniform and the residual amount of strain is small as compared with the cast material. Therefore, the heat treatment also becomes a powder having a good structure at a lower temperature and a shorter time than in the case of the cast material. For the reasons described above, it is considered that the alloy powder obtained by gas atomization is heat-treated and the heat-treated alloy powder is the most suitable powder for batteries.
【０００９】従来、酸処理方法としては、アトマイズさ
れたままの粉末またはそれを熱処理した粉末や焼結体を
塩酸などを純粋で希釈した処理溶液と共に処理層中に投
入した後、周囲の雰囲気の酸素含有量を１ｖｏｌ％以下
に保持した状態で、処理液を攪拌することによって均一
に表面処理を施すのが一般的であった。Conventionally, as an acid treatment method, an as-atomized powder or a powder or a sintered body obtained by heat-treating the same together with a treatment solution obtained by diluting hydrochloric acid or the like into a treatment layer is introduced into a treatment layer. In general, the surface treatment is uniformly performed by stirring the treatment liquid while maintaining the oxygen content at 1 vol% or less.
【００１０】本発明者等は処理終了時のｐＨに対する処
理液や表面処理された粉末の特性に及ぼす影響を詳細に
調査した結果、希土類酸化物の処理液への溶け出しは酸
投入からｐＨ４までにほぼ終了するために、中和域まで
長時間攪拌することにより二次電池として使用した場合
の放電効率や充電の際の電池内圧の上昇に特に影響を及
ぼすニッケルの処理液への溶出を助長し水素吸蔵特性の
向上を阻害していることを見出した。本発明は、この問
題を解決し、すなわちｐＨ４から中和域までを短時間で
処理することによりニッケルの処理液への溶出を抑制す
ることによって、酸処理後の粉末の性能を大幅に向上さ
せると共に表面処理の所要時間を短縮することを目的と
した酸処理方法にある。As a result of a detailed investigation of the effect of the pH of the processing solution and the surface-treated powder on the pH at the end of the processing, the present inventors found that the dissolution of the rare-earth oxide into the processing solution from acid injection to pH 4 By stirring for a long time up to the neutralization zone, the nickel is eluted into the processing solution, which particularly affects the discharge efficiency when used as a secondary battery and the rise in battery internal pressure during charging. It has been found that the improvement in hydrogen storage characteristics is impaired. The present invention solves this problem, that is, significantly reduces the performance of the powder after acid treatment by suppressing the elution of nickel into the treatment solution by treating from pH 4 to the neutralization region in a short time. In addition, there is an acid treatment method aimed at shortening the time required for the surface treatment.
【００１１】[0011]
【課題を解決するための手段】この発明の要旨とすると
ころは、 （１）ミッシュメタル・ニッケル系水素吸蔵合金のガス
アトマイズ法によって得た粉末またはそれを熱処理する
ことによって得た粉末または焼結体を酸溶液中に投入し
た後、ｐＨ４までは周囲の雰囲気の酸素含有量を１ｖｏ
ｌ％以下に保持した状態で、ｐＨ４から中和域までを酸
素含有量を９９ｖｏｌ％以上に保持した状態で攪拌しな
がら表面処理を行うことを特徴とする水素吸蔵合金粉末
の製造方法。 （２）雰囲気はｐＨ４まではアルゴンガスを密閉した状
態またはアルゴンガス気流により、またｐＨ４から中和
域までは酸素ガスを密閉した状態または酸素ガス気流に
よって得られることを特徴とする請求項１記載の水素吸
蔵合金粉末の製造方法にある。The gist of the present invention is as follows: (1) Powder obtained by gas atomizing a misch metal / nickel based hydrogen storage alloy or powder or sintered body obtained by heat-treating the powder Is introduced into an acid solution, and the oxygen content of the surrounding atmosphere is reduced to 1 vol.
A method for producing a hydrogen storage alloy powder, comprising performing surface treatment while stirring at a pH of 4 to a neutralization region while maintaining an oxygen content of 99 vol% or more while maintaining the oxygen content at 1% or less. (2) The atmosphere is obtained in a state in which argon gas is sealed or an argon gas flow up to pH 4, and in an atmosphere with oxygen gas closed or oxygen gas flow from pH 4 to a neutralization region. In the method for producing a hydrogen storage alloy powder.
【００１２】以下、本発明について詳細に説明する。本
発明に係る不活性雰囲気とは、例えば、酸処理を行う容
器として密閉型容器を使用し、粉末と酸処理溶液以外の
空間の大気をアルゴンガス等で置換封入することによっ
て得られる状態である。また容器の一部を開放し、外部
からアルゴンガスを流入させて過剰のガスは開放口から
放出する。また、アルゴンガス気流の方式などによって
も不活性雰囲気が得られる。また、酸素ガス雰囲気につ
いても同様に得られる。Hereinafter, the present invention will be described in detail. The inert atmosphere according to the present invention is, for example, a state obtained by using a closed container as a container for performing the acid treatment, and replacing and enclosing the atmosphere in a space other than the powder and the acid treatment solution with argon gas or the like. . In addition, a part of the container is opened, and argon gas flows in from the outside, and excess gas is discharged from the opening. An inert atmosphere can also be obtained by an argon gas flow system or the like. Further, an oxygen gas atmosphere can be similarly obtained.
【００１３】前述のミッシュメタル・ニッケル系水素吸
蔵合金のアトマイズ粉末、またはその粉末を熱処理して
得られた粉末または焼結体を、攪拌機能を有した湿式ミ
キサーに酸溶液と共に挿入して攪拌する際、ｐＨ４まで
は周囲の雰囲気を不活性にすることによってアトマイズ
粉末の表面は酸処理にすると酸化皮膜が除去され、金属
面が露出された状態になる。しかし不活性雰囲気のまま
中和域まで長時間酸処理をすることによって金属表面の
ニッケルが溶け出していき、水素の吸収・放出の特性が
低下する。一方、酸素雰囲気で処理することによって短
時間での処理が可能になり金属表面のニッケルの溶け出
しが抑えられる。The atomized powder of the above-described misch metal / nickel-based hydrogen storage alloy, or a powder or sintered body obtained by heat-treating the powder is inserted into a wet mixer having a stirring function together with an acid solution and stirred. At this time, the surface of the atomized powder is acid-treated by inactivating the surrounding atmosphere up to pH 4 to remove the oxide film and expose the metal surface. However, when the acid treatment is performed for a long time to the neutralization region in an inert atmosphere, nickel on the metal surface is dissolved, and the characteristics of hydrogen absorption / release are deteriorated. On the other hand, by performing the treatment in an oxygen atmosphere, the treatment can be performed in a short time, and the dissolution of nickel on the metal surface can be suppressed.
【００１４】[0014]
【発明の実施の形態】Ｍｍ1.0 Ｎｉ3.5 Ｃｏ0.7 Ｍｎ
0.5 Ａｌ0.3 を構成するように配合した金属原料をアル
ミナ坩堝に収容し、誘導溶解で溶解した後、１５００℃
の溶湯を直径２ｍｍのノズルを通して落下させ、これに
５Ｎのアルゴンガスを吹き付けて急冷してガスアトマイ
ズ粉末を製造した。得られた粉末を目開き１５０μｍの
ふるいで分級した後、ステンレス容器に収容し、アルゴ
ン気流中で８００℃×１０時間熱処理をした。熱処理後
の粉末を攪拌機能の付いたミキサー中に挿入した後、処
理液としてｐＨ１．０の塩酸溶液を粉末容積１に対して
５の割合で投入し、ｐＨをモニターしながらｐＨ６．５
以上（中和域）になるまで攪拌しながら表面処理を行っ
た。表面処理を施す際の雰囲気として、表１に示した各
条件で行った。DETAILED DESCRIPTION OF THE INVENTION Mm 1.0 Ni 3.5 Co 0.7 Mn
A metal raw material blended to constitute 0.5 Al 0.3 was placed in an alumina crucible and melted by induction melting, and then 1500 ° C.
Was dropped through a nozzle having a diameter of 2 mm, and 5 N argon gas was blown onto the molten metal to quench the molten metal to produce a gas atomized powder. After the obtained powder was classified with a sieve having an opening of 150 μm, it was placed in a stainless steel container and heat-treated at 800 ° C. for 10 hours in an argon stream. After the heat-treated powder is inserted into a mixer equipped with a stirring function, a hydrochloric acid solution having a pH of 1.0 is added as a treatment liquid at a ratio of 5 to a powder volume of 1, and pH 6.5 is monitored while monitoring the pH.
The surface treatment was performed while stirring until the above (neutralization zone) was reached. The atmosphere for the surface treatment was performed under the conditions shown in Table 1.
【００１５】[0015]
【表１】 [Table 1]
【００１６】こうして得られた各試料粉末について、そ
れぞれＮｉ粉末を１０ｗｔ．％混合し、結着剤を加えて
混練し、Ｎｉメッシュに挟んで負極を成形した。この負
極をこれよりも体積の大きい焼結ニッケル電極と組み合
わせてアルカリ溶液に浸漬し、実験用ニッケル水素二次
電池を構成した。この二次電池を負極の規定容量以上の
電気容量を加えて充電し、その後２００ｍＡで放電を終
了させさらに５０ｍＡで残りの容量を放電させ、２００
ｍＡでの放電容量と５０ｍＡでの放電容量とを合計し
て、負極を構成する水素吸蔵合金粉末１ｇあたりに蓄え
られる電気化学容量を求めて表２に示した。またこの電
池の放電効率を求める指標として、２００ｍＡでの容量
と５０ｍＡでの容量の合計に占める２００ｍＡでの容量
をパーセントで示し、電池の活性化度として表２に示し
た。For each of the sample powders thus obtained, 10 wt. %, A binder was added and the mixture was kneaded, and a negative electrode was formed by sandwiching it between Ni meshes. This negative electrode was combined with a sintered nickel electrode having a larger volume and immersed in an alkaline solution to form an experimental nickel-metal hydride secondary battery. This secondary battery is charged by adding an electric capacity equal to or more than the specified capacity of the negative electrode. Thereafter, the discharge is terminated at 200 mA, and the remaining capacity is discharged at 50 mA.
The discharge capacity at 50 mA and the discharge capacity at 50 mA were summed to determine the electrochemical capacity stored per 1 g of the hydrogen storage alloy powder constituting the negative electrode, and the results are shown in Table 2. Further, as an index for calculating the discharge efficiency of this battery, the capacity at 200 mA in the total of the capacity at 200 mA and the capacity at 50 mA is shown as a percentage, and Table 2 shows the degree of activation of the battery.
【００１７】[0017]
【表２】 [Table 2]
【００１８】表２の結果について、単位重量当たり３０
０ｍＡｈ以上の電気化学容量を示す粉末は特性が優れて
いるもので、３１０ｍＡｈ以上の電気化学容量を示す粉
末は特に優れているものである。また活性化度が８５％
以上を示す粉末は特性が優れているもので、９０％以上
を示す粉末は特に優れているものである。以上の結果よ
り酸処理する際、ｐＨ４までは周囲の雰囲気の酸素含有
量を１ｖｏｌ％以下に保持した状態で、ｐＨ４から中和
域までを酸素含有量を９９ｖｏｌ％以上に保持した状態
で攪拌しながら表面処理を行うことによって優れた電気
化学特性の粉末が得られる。また表面処理時間も従来の
約半分以下の時間に抑えることが出来る。The results in Table 2 show that 30
A powder exhibiting an electrochemical capacity of 0 mAh or more has excellent properties, and a powder exhibiting an electrochemical capacity of 310 mAh or more is particularly excellent. 85% activation
Powders showing the above are excellent in characteristics, and powders showing 90% or more are particularly excellent. From the above results, when performing the acid treatment, the oxygen content of the surrounding atmosphere was maintained at 1 vol% or less until pH 4, and the oxygen content was stirred from pH 4 to the neutralization region with the oxygen content maintained at 99 vol% or more. By performing the surface treatment, a powder having excellent electrochemical characteristics can be obtained. Also, the surface treatment time can be reduced to about half or less of the conventional time.
【００１９】[0019]
【発明の効果】以上述べたように、本発明による、酸処
理中の粉末表面の活性面の処理液中への溶け出しを抑え
ることによって、酸処理後の粉末の性能を大幅に向上さ
せることにより、粉末の水素吸蔵速度が大幅に向上し、
その粉末を電極にした場合の電気化学特性も顕著に向上
する極めて優れた効果を奏するものである。As described above, according to the present invention, by suppressing the active surface of the powder surface during the acid treatment from dissolving into the treatment liquid, the performance of the powder after the acid treatment is greatly improved. By this, the hydrogen storage speed of the powder is greatly improved,
When the powder is used as an electrode, an extremely excellent effect of remarkably improving the electrochemical characteristics can be obtained.
Claims (2)
金のガスアトマイズ法によって得た粉末またはそれを熱
処理することによって得た粉末または焼結体を酸溶液中
に投入した後、ｐＨ４までは周囲の雰囲気の酸素含有量
を１ｖｏｌ％以下に保持した状態で、ｐＨ４から中和域
までを酸素含有量を９９ｖｏｌ％以上に保持した状態で
攪拌しながら表面処理を行うことを特徴とする水素吸蔵
合金粉末の製造方法。After a powder obtained by gas atomizing a misch metal / nickel-based hydrogen storage alloy or a powder or a sintered body obtained by heat-treating the same is introduced into an acid solution, the pH of the surrounding atmosphere is increased up to pH4. A method for producing a hydrogen storage alloy powder, characterized in that surface treatment is performed while stirring the oxygen content from 1 to 4 in a state where the oxygen content is kept at 1 vol% or less while maintaining the oxygen content at 99 vol% or more from pH 4 to the neutralization region. Method.
閉した状態またはアルゴンガス気流により、またｐＨ４
から中和域までは酸素ガスを密閉した状態または酸素ガ
ス気流によって得られることを特徴とする請求項１記載
の水素吸蔵合金粉末の製造方法。2. An atmosphere up to pH 4 in a state in which an argon gas is sealed or an argon gas flow is used.
The method for producing a hydrogen storage alloy powder according to claim 1, wherein the oxygen gas is obtained in a state in which oxygen gas is sealed or in an oxygen gas stream from the region up to the neutralization region.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9313064A JPH11140501A (en) | 1997-11-14 | 1997-11-14 | Production of hydrogen storage alloy powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9313064A JPH11140501A (en) | 1997-11-14 | 1997-11-14 | Production of hydrogen storage alloy powder |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11140501A true JPH11140501A (en) | 1999-05-25 |
Family
ID=18036783
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9313064A Withdrawn JPH11140501A (en) | 1997-11-14 | 1997-11-14 | Production of hydrogen storage alloy powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH11140501A (en) |
-
1997
- 1997-11-14 JP JP9313064A patent/JPH11140501A/en not_active Withdrawn
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