JP2000268814A - Hydrogen storage alloy electrode and nickel-hydrogen storage battery using the same - Google Patents
Hydrogen storage alloy electrode and nickel-hydrogen storage battery using the sameInfo
- Publication number
- JP2000268814A JP2000268814A JP11070516A JP7051699A JP2000268814A JP 2000268814 A JP2000268814 A JP 2000268814A JP 11070516 A JP11070516 A JP 11070516A JP 7051699 A JP7051699 A JP 7051699A JP 2000268814 A JP2000268814 A JP 2000268814A
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- Prior art keywords
- hydrogen storage
- storage alloy
- cobalt
- nickel
- cobalt oxide
- Prior art date
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- 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
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本究明は、水素吸蔵合金を用
いた水素吸蔵合金電極に係り、特に、高率放電特性に優
れた水素吸蔵合金電極およびこの水素吸蔵合金電極を用
いたニッケル・水素蓄電池に関するものである。The present invention relates to a hydrogen storage alloy electrode using a hydrogen storage alloy, and more particularly to a hydrogen storage alloy electrode excellent in high-rate discharge characteristics and a nickel-hydrogen storage battery using the hydrogen storage alloy electrode. It is about.
【０００２】[0002]
【従来の技術】近年、正極に水酸化ニッケルなどの金属
化合物を使用し、負極に水素吸蔵合金を使用したニッケ
ル・水素蓄電池が、ニッケル・カドミウム蓄電池に代わ
る次世代のアルカリ蓄電池として広く用いられるように
なってきた。この種のニッケル・水素蓄電池は、ニッケ
ル・カドミウム蓄電池と比較してエネルギー密度が大き
く、かつ負極にカドミウムを使用しないことから環境適
合性が高いという特徴を有している。2. Description of the Related Art In recent years, nickel-metal hydride storage batteries using a metal compound such as nickel hydroxide for the positive electrode and a hydrogen storage alloy for the negative electrode have been widely used as next-generation alkaline storage batteries in place of nickel-cadmium storage batteries. It has become This type of nickel-metal hydride storage battery has a feature that the energy density is higher than that of a nickel-cadmium storage battery, and that it does not use cadmium for the negative electrode, and thus has high environmental compatibility.
【０００３】このため、携帯電話、ノートブック型パー
ソナルコンピュータ等の携帯機器用電源としての需要が
急速に拡大し、これに伴って、ニッケル・水素蓄電池の
さらなる高容量化、長寿命化が要求されるようになって
きた。また、電気自動車の電源としてのニッケル・水素
蓄電池も開発され、その需要も、今後、急速に拡大して
いくものと予想される。電気自動車用の電源として用い
られる蓄電池としては、高容量で長寿命であるととも
に、高出力であることが特に要求される。For this reason, demand for a power source for portable equipment such as a portable telephone and a notebook personal computer has been rapidly expanding, and accordingly, a higher capacity and longer life of a nickel-metal hydride storage battery has been required. It has become. Nickel-metal hydride storage batteries have also been developed as power sources for electric vehicles, and their demand is expected to increase rapidly in the future. A storage battery used as a power supply for an electric vehicle is particularly required to have high capacity, long life, and high output.
【０００４】[0004]
【発明が解決しようとする課題】ところで、ニッケル・
水素蓄電池はニッケル・カドミウム蓄電池に比べてハイ
レート放電特性（高率放電特性）が劣るため、高出力が
要求される用途に用いる場合にはハイレート放電特性を
さらに向上させる必要がある。このため、例えば、特開
平１０−３９３９号公報において、初期の充放電サイク
ル特性を向上させたニッケル・水素蓄電池が提案されて
いる。この特開平１０−３９３９号公報において提案さ
れたニッケル・水素蓄電池は、二価の酸化コバルトを水
素吸蔵合金電極に添加し、電解液中に生成した二価のコ
バルト錯イオン（ＨＣｏＯ2 -）を還元させ、あるいは添
加した二価の酸化コバルトを充電により直接還元させ
て、水素吸蔵合金表面にコバルト金属からなる層を形成
させるようにしている。SUMMARY OF THE INVENTION By the way, nickel
Since the hydrogen storage battery is inferior in high-rate discharge characteristics (high-rate discharge characteristics) as compared with nickel-cadmium storage batteries, it is necessary to further improve the high-rate discharge characteristics when used in applications requiring high output. For this reason, for example, Japanese Patent Application Laid-Open No. 10-3939 proposes a nickel-hydrogen storage battery in which the initial charge / discharge cycle characteristics are improved. The nickel-hydrogen storage battery proposed in Japanese Patent Application Laid-Open No. 10-3939 discloses a method of adding divalent cobalt oxide to a hydrogen storage alloy electrode to convert divalent cobalt complex ions (HCoO 2 − ) generated in an electrolyte solution. The reduction or the added divalent cobalt oxide is directly reduced by charging to form a layer made of cobalt metal on the surface of the hydrogen storage alloy.
【０００５】しかしながら、特開平１０−３９３９号公
報において提案されたニッケル・水素蓄電池にあって
は、大部分のコバルト化合物（二価の酸化コバルト）は
還元されておらず、電解液中の酸素により酸化されて、
電気化学的に不活性な黒色の四三酸化コバルト（Ｃｏ3
Ｏ4）となっていることが分かった。結果として、初期
の充放電サイクル特性の向上にはある程度の効果がある
ものの、不活性な四三酸化コバルト（Ｃｏ3Ｏ4）で水素
吸蔵合金表面が被覆されるために、高率放電特性の向上
には効果が小さいという問題点があった。However, in the nickel-metal hydride storage battery proposed in Japanese Patent Application Laid-Open No. 10-3939, most of the cobalt compounds (divalent cobalt oxide) are not reduced, and are not reduced by oxygen in the electrolyte. Oxidized,
Electrochemically inert black cobalt trioxide (Co 3
O 4 ). As a result, although there is a certain effect on the improvement of the initial charge-discharge cycle characteristics, since the surface of the hydrogen storage alloy is coated with inert cobalt trioxide (Co 3 O 4 ), the high-rate discharge characteristics are improved. There was a problem that the effect was small for improvement.
【０００６】[0006]
【課題を解決するための手段およびその作用効果】そこ
で、本発明は上記問題点に鑑みてなされたものであっ
て、その目的とするところは、高率放電特性に優れた水
素吸蔵合金電極を得て、高容量で長寿命であるととも
に、高出力であるニッケル・水素蓄電池を得ることにあ
る。このため、本発明の水素吸蔵合金電極は、少なくと
も水素吸蔵合金粉末に、その表面がコバルト金属で被覆
されたコバルト酸化物（ＣｏＯ）粉末が添加、混合され
ている。SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a hydrogen storage alloy electrode having excellent high rate discharge characteristics. It is another object of the present invention to provide a nickel-metal hydride storage battery having a high capacity, a long life and a high output. Therefore, in the hydrogen storage alloy electrode of the present invention, cobalt oxide (CoO) powder whose surface is coated with cobalt metal is added to and mixed with at least the hydrogen storage alloy powder.
【０００７】二価のコバルトの金属コバルトヘの還元電
位は水素発生電位より貴であり、電気化学的には金属へ
の還元が可能であるが、電解液中の酸素により酸化され
て四三酸化コバルト（Ｃｏ3Ｏ4）が一旦生成すると容易
には還元されなくなる。このため、コバルト酸化物（Ｃ
ｏＯ）の代わりに表面のみを還元させて、その表面がコ
バルト金属で被覆されたコバルト酸化物を添加したとこ
ろ、初期の充電によって電解液中のコバルトイオンおよ
び酸化コバルト（ＣｏＯ）の金属コバルトへの還元が効
果的に起こり、高率放電特性が大きく向上することが分
かった。これは、酸化コバルト（ＣｏＯ）は同一粒子内
の還元された金属コバルトの電位に保持されて、四三酸
化コバルト（Ｃｏ3Ｏ4）への酸化が抑制されているもの
と考えられる。The reduction potential of divalent cobalt to metallic cobalt is more noble than the hydrogen generation potential, and can be electrochemically reduced to metal. However, it is oxidized by oxygen in the electrolyte to form cobalt trioxide. Once (Co 3 O 4 ) is formed, it is not easily reduced. Therefore, cobalt oxide (C
When only the surface was reduced instead of oO) and cobalt oxide whose surface was coated with cobalt metal was added, the initial charge caused the conversion of cobalt ions and cobalt oxide (CoO) in the electrolytic solution to metallic cobalt. It was found that the reduction occurred effectively and the high rate discharge characteristics were greatly improved. This is presumably because cobalt oxide (CoO) is held at the potential of reduced metallic cobalt in the same particle, and oxidation to cobalt trioxide (Co 3 O 4 ) is suppressed.
【０００８】コバルト金属粉を水素吸蔵合金粉末に直接
添加、混合する方法も考えられるが、コバルト金属紛の
場合、最小でも水素吸蔵合金粒子に近い大きさの粒子し
か調整できない。このため、より小さい粒径のコバルト
金属粒子を用いた場合に比べて、添加量の割に水素吸蔵
合金との接点が少なく、導電剤としての効果が小さい。
一方、本発明のように、酸化コバルトを出発物質として
用いれば、サブミクロンオーダーの微粒子を調整するこ
とも可能となり、これが電池内ですべて還元されてコバ
ルト金属となる。これにより、導電剤として効果的に作
用するほか、表面積効果によって電極反応に対する触媒
作用が著しく高まり、高率放電特性向上に対して高い効
果が得られるようになる。A method of directly adding and mixing the cobalt metal powder to the hydrogen storage alloy powder is also conceivable. However, in the case of the cobalt metal powder, only particles having a size close to the hydrogen storage alloy particles can be adjusted at least. Therefore, compared with the case where cobalt metal particles having a smaller particle size are used, the number of contacts with the hydrogen storage alloy is small for the added amount, and the effect as a conductive agent is small.
On the other hand, when cobalt oxide is used as a starting material as in the present invention, it is also possible to adjust submicron-order fine particles, which are all reduced in the battery to become cobalt metal. As a result, in addition to effectively acting as a conductive agent, a catalytic effect on an electrode reaction is remarkably enhanced by a surface area effect, and a high effect on improvement in high rate discharge characteristics can be obtained.
【０００９】[0009]
【発明の実施の形態】１．水素吸蔵合金粉末の作製 Ｍｍ（希土類元素の混合物），Ｎｉ，Ｃｏ，Ａｌ，Ｍｎ
（純度９９．９％の金属単体）をモル比１．０：３．
１：０．８：０．４：０．７の割合で混合し、アルゴン
雰囲気のアーク溶解炉で溶解させた後、自然放冷して、
組成式がＭｍＮｉ 3.1ＣｏO.8Ａｌ0.4ＭｎO.7で表される
水素吸蔵合金のインゴットを作製した。このようにして
作製した水素吸蔵合金のインゴットを８００℃で６時間
熱処理した後、放冷し、不活性雰囲気下で平均粒径が約
６５μｍになるまで機械紛砕して、水素吸蔵合金粉末を
作製した。BEST MODE FOR CARRYING OUT THE INVENTION Preparation of hydrogen storage alloy powder Mm (mixture of rare earth elements), Ni, Co, Al, Mn
(A simple metal having a purity of 99.9%) in a molar ratio of 1.0: 3.
Mixing in a ratio of 1: 0.8: 0.4: 0.7, argon
After melting in an atmosphere arc melting furnace, let it cool naturally,
The composition formula is MmNi 3.1CoO.8Al0.4MnO.7Represented by
A hydrogen storage alloy ingot was manufactured. Like this
Prepared hydrogen storage alloy ingot at 800 ° C for 6 hours
After heat treatment, allow to cool and have an average particle size of about
Mechanically crushed to 65μm, and the hydrogen storage alloy powder
Produced.
【００１０】２．表面をコバルト金属に還元した酸化コ
バルト粉末の作製 平均粒径が２０μｍの市販の二価の酸化コバルトを水素
流通雰囲気下で５００℃で３０分間加熱することによっ
て、二価の酸化コバルトの表面部分のみを還元させた。
このようにして水素流通雰囲気下で還元された二価の酸
化コバルトをＸＰＳ（Ｘ線光分子分光法）を用いて測定
すると、コバルト金属のピークが深さ方向に進むにした
がって小さくなっていることが分かった。このことか
ら、二価の酸化コバルトの表面部分のみが還元されてい
ることが確認できた。また、水素流通雰囲気下での還元
処理の前後で、その重量を測定することによって、二価
の酸化コバルトの還元率を求めた。その結果、コバルト
金属への還元率は約１２原子％であることが分かった。
さらに、レーザー回折散乱法によって平均粒径を測定し
た結果、その平均粒径は１８μｍであることが分かっ
た。[0010] 2. Preparation of Cobalt Oxide Powder with Surface Reduced to Cobalt Metal By heating a commercially available divalent cobalt oxide having an average particle size of 20 μm at 500 ° C. for 30 minutes in a hydrogen flowing atmosphere, only the surface portion of the divalent cobalt oxide is heated. Was reduced.
When the divalent cobalt oxide reduced in the hydrogen flowing atmosphere in this way is measured by XPS (X-ray photo-molecular spectroscopy), the peak of the cobalt metal becomes smaller as it proceeds in the depth direction. I understood. This confirmed that only the surface portion of divalent cobalt oxide was reduced. Further, before and after the reduction treatment in a hydrogen circulation atmosphere, the weight was measured to determine the reduction rate of divalent cobalt oxide. As a result, the reduction rate to cobalt metal was found to be about 12 atomic%.
Furthermore, as a result of measuring the average particle size by the laser diffraction scattering method, it was found that the average particle size was 18 μm.
【００１１】３．水素吸蔵合金電極の作製 （１）実施例１ 上述のようにして作製した水素吸蔵合金粉末に、結着剤
としてのポリエチレンオキサイドの５重量％水溶液を水
素吸蔵合金粉末に対して２０重量％を添加し、混合して
水素吸蔵合金ペーストを作製した。この水素吸蔵合金ペ
ーストに、上述のようにして作製した表面を還元した二
価の酸化コバルト粉末を水素吸蔵合金粉末に対して１．
０重量％添加し、混合した。ついで、この混合物をニッ
ケルメッキを施したパンチングメタルからなる芯体の両
面に塗着し、室温で乾燥した後、所定の寸法に切断し
て、実施例１の水素吸蔵合金電極ａを作製した。3. Preparation of Hydrogen Storage Alloy Electrode (1) Example 1 To the hydrogen storage alloy powder prepared as described above, a 5% by weight aqueous solution of polyethylene oxide as a binder was added at 20% by weight based on the hydrogen storage alloy powder. Then, they were mixed to prepare a hydrogen storage alloy paste. To this hydrogen-absorbing alloy paste was added the surface-reduced divalent cobalt oxide powder produced as described above to the hydrogen-absorbing alloy powder.
0% by weight was added and mixed. Then, this mixture was applied to both surfaces of a core body made of a nickel-plated punched metal, dried at room temperature, and then cut into a predetermined size to prepare a hydrogen storage alloy electrode a of Example 1.
【００１２】（２）比較例１ 上述のようにして作製した水素吸蔵合金粉末に、結着剤
としてのポリエチレンオキサイドの５重量％水溶液を水
素吸蔵合金粉末に対して２０重量％を添加し、混合して
水素吸蔵合金ペーストを作製した。この水素吸蔵合金ペ
ーストに、金属コバルト粉末を水素吸蔵合金粉末に対し
て１．０重量％添加し、混合した。ついで、この混合物
を、ニッケルメッキを施したパンチングメタルからなる
芯体の両面に塗着し、室温で乾燥した後、所定の寸法に
切断して、比較例１の水素吸蔵合金電極ｘを作製した。(2) Comparative Example 1 A 5% by weight aqueous solution of polyethylene oxide as a binder was added to the hydrogen storage alloy powder prepared as described above, and 20% by weight based on the hydrogen storage alloy powder was added. Thus, a hydrogen storage alloy paste was produced. To the hydrogen storage alloy paste, 1.0% by weight of metal cobalt powder was added to the hydrogen storage alloy powder and mixed. Next, this mixture was applied to both surfaces of a core body made of a nickel-plated punched metal, dried at room temperature, and then cut to a predetermined size to produce a hydrogen storage alloy electrode x of Comparative Example 1. .
【００１３】（３）比較例２ 上述のようにして作製した水素吸蔵合金粉末に、結着剤
としてのポリエチレンオキサイドの５重量％水溶液を水
素吸蔵合金粉末に対して２０重量％を添加し、混合して
水素吸蔵合金ペーストを作製した。この水素吸蔵合金ペ
ーストに、酸化コバルト粉末を水素吸蔵合金粉末に対し
て１．０重量％添加し、混合した。ついで、この混合物
を、ニッケルメッキを施したパンチングメタルからなる
芯体の両面に塗着し、室温で乾燥した後、所定の寸法に
切断して、比較例２の水素吸蔵合金電極ｙを作製した。(3) Comparative Example 2 A 5% by weight aqueous solution of polyethylene oxide as a binder was added to the hydrogen storage alloy powder prepared as described above, and 20% by weight of the hydrogen storage alloy powder was added. Thus, a hydrogen storage alloy paste was produced. Cobalt oxide powder was added to the hydrogen storage alloy paste in an amount of 1.0% by weight based on the hydrogen storage alloy powder and mixed. Next, this mixture was applied to both surfaces of a core body made of a nickel-plated punched metal, dried at room temperature, and then cut to a predetermined size to produce a hydrogen storage alloy electrode y of Comparative Example 2. .
【００１４】（４）比較例３ 上述のようにして作製した水素吸蔵合金粉末に、結着剤
としてのポリエチレンオキサイドの５重量％水溶液を水
素吸蔵合金粉末に対して２０重量％を添加し、混合して
水素吸蔵合金ペーストを作製した。この水素吸蔵合金ペ
ーストを、ニッケルメッキを施したパンチングメタルか
らなる芯体の両面に塗着し、室温で乾燥した後、所定の
寸法に切断して、比較例３の水素吸蔵合金電極ｚを作製
した。(4) Comparative Example 3 A 5% by weight aqueous solution of polyethylene oxide as a binder was added to the hydrogen storage alloy powder prepared as described above, and 20% by weight based on the hydrogen storage alloy powder was added. Thus, a hydrogen storage alloy paste was produced. This hydrogen-absorbing alloy paste was applied to both surfaces of a nickel-plated core made of punched metal, dried at room temperature, and then cut into predetermined dimensions to produce a hydrogen-absorbing alloy electrode z of Comparative Example 3. did.
【００１５】４．ニッケル−水素蓄電池の作製 これらの各水素吸蔵合金電極ａ，ｘ，ｙ，ｚを負極とし
て、水酸化ニッケルを主成分とする公知の焼結式ニッケ
ル極を正極とし、これらの両極の間に耐アルカリ性の不
繊布よりなるセパレーターを介在させて、それぞれ渦巻
状に巻回して４種類の渦巻状電極群を作製した。つい
で、これらの各渦巻状電極群をそれぞれの電池外装缶内
に配設した後、３０重量％の水酸化カリウム水溶液から
なる電解液を注入して、４種類の電池容量が１０００ｍ
Ａｈのニッケル−水素蓄電池（ＡＡサイズで正極支配
型）を作製した。4. Preparation of Nickel-Hydrogen Storage Battery Each of these hydrogen storage alloy electrodes a, x, y, and z is used as a negative electrode, and a known sintered nickel electrode containing nickel hydroxide as a main component is used as a positive electrode. Each of them was spirally wound with a separator made of alkaline non-woven cloth interposed therebetween, thereby producing four types of spiral electrode groups. Then, after each of these spiral electrode groups is disposed in each battery outer can, an electrolytic solution consisting of a 30 wt% aqueous solution of potassium hydroxide is injected, and the four types of battery capacities are 1000 m.
An Ah nickel-hydrogen storage battery (AA size, positive electrode dominant type) was produced.
【００１６】なお、実施例１の水素吸蔵合金電極ａを用
いたニッケル−水素蓄電池を実施例１の電池Ａとし、比
較例１の水素吸蔵合金電極ｘを用いたニッケル−水素蓄
電池を比較例１の電池Ｘとし、比較例２の水素吸蔵合金
電極ｙを用いたニッケル−水素蓄電池を比較例２の電池
Ｙとし、比較例３の水素吸蔵合金電極ｚを用いたニッケ
ル−水素蓄電池を比較例３の電池Ｚとした。The nickel-hydrogen storage battery using the hydrogen storage alloy electrode a of Example 1 is referred to as battery A of Example 1, and the nickel-hydrogen storage battery using the hydrogen storage alloy electrode x of Comparative Example 1 is referred to as Comparative Example 1. The battery X of Comparative Example 2, the nickel-hydrogen storage battery using the hydrogen storage alloy electrode y of Comparative Example 2 was referred to as Battery Y of Comparative Example 2, and the nickel-hydrogen storage battery using the hydrogen storage alloy electrode z of Comparative Example 3 was Comparative Example 3. Of battery Z.
【００１７】５．充放電試験 ついで、上述のように作製した４種類の各ニッケル−水
素蓄電池を１００ｍＡ（０．１Ｃ）の充電々流で１２時
間充電した後、１時間休止させる。その後、１０００ｍ
Ａ（１Ｃ）の放電々流で終止電圧が１．０Ｖになるまで
放電させた後、１時間休止させる。この充放電を室温で
所定回数繰り返す充放電試験を行った。この後、１００
０ｍＡ（１Ｃ）の放電々流で終止電圧が１．０Ｖになる
まで放電させて、放電時間から１Ｃ放電時の放電容量
（１Ｃ放電容量）を求めた。5. Charge / Discharge Test Next, each of the four types of nickel-hydrogen storage batteries produced as described above is charged with a charge current of 100 mA (0.1 C) for 12 hours, and then paused for 1 hour. After that, 1000m
After the discharge at the discharge current of A (1C) until the final voltage reaches 1.0 V, the apparatus is paused for 1 hour. A charge / discharge test in which this charge / discharge was repeated a predetermined number of times at room temperature was performed. After this, 100
The discharge was performed at a discharge current of 0 mA (1 C) until the final voltage reached 1.0 V, and the discharge capacity at the time of 1 C discharge (1 C discharge capacity) was determined from the discharge time.
【００１８】一方、上述のように作製した４種類の各ニ
ッケル−水素蓄電池を１００ｍＡ（０．１Ｃ）の充電々
流で１２時間充電した後、１時間休止させる。その後、
４０００ｍＡ（４Ｃ）の放電々流で終止電圧が１．０Ｖ
になるまで放電させた後、１時間休止させる。この充放
電を室温で所定回数繰り返す充放電試験を行った。この
後、４０００ｍＡ（４Ｃ）の放電々流で終止電圧が１．
０Ｖになるまで放電させて、放電時間から４Ｃ放電時の
放電容量（４Ｃ放電容量）を求め、１Ｃ放電容量に対す
る４Ｃ放電容量を放電容量比（＝（４Ｃ放電容量）／
（１Ｃ放電容量））として求めた。この結果を下記の表
１に示した。On the other hand, each of the four types of nickel-metal hydride storage batteries manufactured as described above is charged for 12 hours with a charging current of 100 mA (0.1 C), and then stopped for 1 hour. afterwards,
A cut-off voltage of 1.0 V at a discharge current of 4000 mA (4 C)
And then pause for 1 hour. A charge / discharge test in which this charge / discharge was repeated a predetermined number of times at room temperature was performed. Thereafter, the discharge voltage of 4000 mA (4 C) causes a cutoff voltage of 1.
The discharge was performed until the voltage reached 0 V, the discharge capacity at the time of 4C discharge (4C discharge capacity) was determined from the discharge time, and the 4C discharge capacity to the 1C discharge capacity was calculated as the discharge capacity ratio (= (4C discharge capacity) /
(1C discharge capacity)). The results are shown in Table 1 below.
【００１９】[0019]
【表１】 [Table 1]
【００２０】上記表１から明らかなように、各電池Ａ，
Ｘ，Ｙ，Ｚの１Ｃ放電時の電池容量（１Ｃ放電容量）は
いずれも９５０ｍＡｈで等しかったが、４Ｃ放電時の放
電容量（４Ｃ放電容量）はそれぞれの電池で異なり，表
面を還元した酸化コバルト紛未を添加した電池Ａで最も
高い放電容量が得られた。また、二価の酸化コバルトを
添加した電池Ｙは、なにも添加していない電池Ｚよりも
高率放電特性が向上したが、その効果はあまり大きくは
なかった。As apparent from Table 1 above, each battery A,
The battery capacity (1C discharge capacity) at the time of 1C discharge of X, Y, and Z was equal to 950 mAh, but the discharge capacity at the time of 4C discharge (4C discharge capacity) was different for each battery, and the surface reduced cobalt oxide. The highest discharge capacity was obtained in the battery A to which the powder was added. The battery Y to which divalent cobalt oxide was added had improved high-rate discharge characteristics as compared to the battery Z to which nothing was added, but the effect was not so large.
【００２１】これは、二価の酸化コバルトを添加した場
合でも、初期充電あるいは充放電を繰り返すことによっ
てコバルト金属への還元が起こるため、ある程度の高率
放電特性向上効果があるものと考えられる。しかしなが
ら、過充電時に正極から発生する酸素によって電解液中
のコバルトイオンの大部分は酸化を受け、不活性な四三
酸化コバルト（Ｃｏ3Ｏ4）が生成する。また、二価の酸
化コバルトの表面でも同様に四三酸化コバルト（Ｃｏ3
Ｏ4）が生成して酸化コバルトの還元が進行しなくなる
ため、電気化学的に利用されるコバルトの量はわずかで
あって、高率放電特性を向上させる効果が少ないものと
考えられる。This is considered to be because even when divalent cobalt oxide is added, reduction to cobalt metal occurs by repeating initial charging or charging / discharging, and thus has an effect of improving the high-rate discharge characteristics to some extent. However, most of the cobalt ions in the electrolytic solution are oxidized by oxygen generated from the positive electrode at the time of overcharge, and inert cobalt trioxide (Co 3 O 4 ) is generated. Similarly, on the surface of divalent cobalt oxide, cobalt trioxide (Co 3
Since O 4 ) is generated and the reduction of cobalt oxide does not proceed, the amount of cobalt used electrochemically is small, and it is considered that the effect of improving the high rate discharge characteristics is small.
【００２２】また、コバルト金属粉末を添加した電池Ｘ
は、コバルト粒子自体が導電剤としての役割を果たし
て、合金粒子同士の接触抵抗を低減させるため、高率放
電特性向上に一定の効果が得られる。しかしながら，電
気化学反応に対するコバルトの触媒的な効果はほとんど
得られないため、高率放電特性を向上させる効果が小さ
くなったと考えられる。Further, a battery X to which cobalt metal powder is added
Since the cobalt particles themselves play a role as a conductive agent and reduce the contact resistance between the alloy particles, a certain effect is obtained in improving the high-rate discharge characteristics. However, since the catalytic effect of cobalt on the electrochemical reaction is hardly obtained, it is considered that the effect of improving the high-rate discharge characteristics is reduced.
【００２３】一方，本発明の表面を還元させた酸化コバ
ルト粉末を用いた電池Ａの場合、１Ｃ放電容量に比べて
４Ｃ放電容量の低下が小さく、高率放電特性が著しく改
善された。これは、コバルト金属粒子を直接添加した場
合においては、水素吸蔵合金との接触が点接触であるの
に対して、表面が還元された酸化コバルト粉末の場合は
酸化コバルト粒子が効果的に還元されて水素吸蔵合金粒
子とつながるため、導電剤としての機能と電気化学的な
触媒としての機能と両機能を併せ持つようになる。この
結果、これらの両機能の効果によって高率放電特性が大
きく向上したものと考えられる。On the other hand, in the case of the battery A using the cobalt oxide powder whose surface has been reduced according to the present invention, the decrease in the 4C discharge capacity was smaller than that in the 1C discharge capacity, and the high rate discharge characteristics were remarkably improved. This is because, when the cobalt metal particles are directly added, the contact with the hydrogen storage alloy is point contact, whereas in the case of the cobalt oxide powder whose surface is reduced, the cobalt oxide particles are effectively reduced. Thus, they are connected to the hydrogen storage alloy particles, so that they have both functions as a conductive agent and a function as an electrochemical catalyst. As a result, it is considered that the high-rate discharge characteristics were greatly improved by the effects of both these functions.
【００２４】なお、それぞれのコバルト化合物を添加し
た各電池Ａ，Ｙを１回充放電させた後、Ｘ線光電子分光
法（ＸＰＳ）で水素吸蔵合金電極ａ，ｙを観察したとこ
ろ、酸化コバルトのみを添加した水素吸蔵合金電極ｙに
おいては、電極ｙ中に還元されていない酸化コバルトが
残存していた。一方、表面を還元した酸化コバルト粉末
を添加した水素吸蔵合金電極ａにおいては、酸化物はほ
とんど残っておらず、酸化コバルトの還元が効率的に行
われたことが確かめられた。After each of the batteries A and Y to which each cobalt compound was added was charged and discharged once, the hydrogen storage alloy electrodes a and y were observed by X-ray photoelectron spectroscopy (XPS). In the hydrogen storage alloy electrode y to which was added, unreduced cobalt oxide remained in the electrode y. On the other hand, in the hydrogen storage alloy electrode a to which the cobalt oxide powder whose surface was reduced was added, almost no oxide remained, confirming that the reduction of cobalt oxide was performed efficiently.
【００２５】６．コバルト添加量の検討 ついで、水素吸蔵合金電極に添加するコバルト化合物
（二価の酸化コバルト）の添加量について比較検討し
た。 （１）実施例２〜７ 上述の実施例１と同様に作製した水素吸蔵合金粉末に、
上述の実施例１と同様に水素吸蔵合金ペーストを作製し
た後、この水素吸蔵合金ペーストに、上述の実施例１と
同様にして作製した表面を還元した二価の酸化コバルト
粉末を、水素吸蔵合金粉末に対してそれぞれ０．０５重
量％、０．１重量％、０．５重量％、３．０重量％、
５．０重量％、１０重量％添加し、混合した以外は上述
の実施例１と同様にして水素吸蔵合金電極を作製した。6. Examination of the amount of cobalt added Next, the amount of the cobalt compound (divalent cobalt oxide) added to the hydrogen storage alloy electrode was compared and examined. (1) Examples 2 to 7 The hydrogen storage alloy powder produced in the same manner as in Example 1
After preparing the hydrogen storage alloy paste in the same manner as in Example 1 described above, a divalent cobalt oxide powder whose surface has been reduced in the same manner as in Example 1 described above is added to the hydrogen storage alloy paste. 0.05% by weight, 0.1% by weight, 0.5% by weight, 3.0% by weight,
A hydrogen storage alloy electrode was produced in the same manner as in Example 1 except that 5.0% by weight and 10% by weight were added and mixed.
【００２６】ここで、表面を還元した二価の酸化コバル
ト粉末を０．０５重量％添加したものを実施例２の水素
吸蔵合金電極ｂとし、０．１重量％添加したものを実施
例３の水素吸蔵合金電極ｃとし、０．５重量％添加した
ものを実施例４の水素吸蔵合金電極ｄとし、３．０重量
％添加したものを実施例５の水素吸蔵合金電極ｅとし、
５．０重量％添加したものを実施例６の水素吸蔵合金電
極ｆとし、１０重量％添加したものを実施例７の水素吸
蔵合金電極ｇとした。Here, the hydrogen storage alloy electrode b of Example 2 was added with 0.05% by weight of divalent cobalt oxide powder whose surface was reduced, and the electrode of Example 3 was added with 0.1% by weight. As the hydrogen storage alloy electrode c, the one added with 0.5% by weight was used as the hydrogen storage alloy electrode d of Example 4, the one added with 3.0% by weight was used as the hydrogen storage alloy electrode e of Example 5,
The one with 5.0 wt% added was the hydrogen storage alloy electrode f of Example 6, and the one with 10 wt% added was the hydrogen storage alloy electrode g of Example 7.
【００２７】（２）放電容量比 これらの各水素吸蔵合金電極ｂ，ｃ，ｄ，ｅ，ｆ，ｇを
用いて、上述の実施例１と同様にしてニッケル−水素蓄
電池を作製し、上述と同様に充放電試験を行い、１Ｃ
（１０００ｍＡ）放電時の放電容量（１Ｃ放電容量）に
対する４Ｃ（４０００ｍＡ）放電時の放電容量（４Ｃ放
電容量）の比を求めると、下記の表２に示すような結果
となった。なお、水素吸蔵合金電極ｂを用いたニッケル
−水素蓄電池を実施例２の電池Ｂとし、水素吸蔵合金電
極ｃを用いたニッケル−水素蓄電池を実施例３の電池Ｃ
とし、水素吸蔵合金電極ｄを用いたニッケル−水素蓄電
池を実施例４の電池Ｄとし、水素吸蔵合金電極ｅを用い
たニッケル−水素蓄電池を実施例５の電池Ｅとし、水素
吸蔵合金電極ｆを用いたニッケル−水素蓄電池を実施例
６の電池Ｆとし、水素吸蔵合金電極ｇを用いたニッケル
−水素蓄電池を実施例７の電池Ｇとした。(2) Discharge capacity ratio Using these hydrogen storage alloy electrodes b, c, d, e, f, and g, a nickel-hydrogen storage battery was manufactured in the same manner as in the above-described first embodiment. A charge / discharge test was performed in the same manner and 1C
When the ratio of the discharge capacity (4C discharge capacity) at the time of 4C (4000 mA) discharge to the discharge capacity (1C discharge capacity) at the time of (1000 mA) discharge was obtained, the results shown in Table 2 below were obtained. The nickel-hydrogen storage battery using the hydrogen storage alloy electrode b is referred to as battery B of Example 2, and the nickel-hydrogen storage battery using the hydrogen storage alloy electrode c is referred to as battery C of Example 3.
The nickel-hydrogen storage battery using the hydrogen storage alloy electrode d is referred to as battery D of Example 4, the nickel-hydrogen storage battery using the hydrogen storage alloy electrode e is referred to as battery E of Example 5, and the hydrogen storage alloy electrode f is referred to as battery E. The nickel-hydrogen storage battery used was battery F of Example 6, and the nickel-hydrogen storage battery using the hydrogen storage alloy electrode g was battery G of Example 7.
【００２８】[0028]
【表２】 [Table 2]
【００２９】上記表２から明らかなように、電池Ａおよ
び各電池Ｂ〜Ｇの１Ｃ放電時の電池容量はいずれも９４
５〜９５０ｍＡｈであった。そして、表面を還元した酸
化コバルト粉末は０．０５重量％を添加しただけでも高
率放電特性を向上させる効果があるが、添加量が０．１
重量％を越えると高率放電特性はさらに大きく向上し
た。これは、酸化コバルトが水素吸蔵合金表面上で還元
された場合、金属コバルトは水素吸蔵合金表面上で電気
化学反応を促進させる触媒の役割を果たしたと考えられ
る。As apparent from Table 2, the battery capacity of each of the battery A and each of the batteries B to G at the time of 1C discharge is 94.
5 to 950 mAh. The cobalt oxide powder whose surface has been reduced has the effect of improving the high-rate discharge characteristics even if only 0.05% by weight is added.
When the content exceeds 10% by weight, the high rate discharge characteristics are further improved. This is presumably because when cobalt oxide was reduced on the surface of the hydrogen storage alloy, metallic cobalt played a role of a catalyst for promoting an electrochemical reaction on the surface of the hydrogen storage alloy.
【００３０】そして、触媒の役割は、酸化コバルトの添
加量がわずかであっても効果を発揮するが、表面の金属
コバルトが導電剤としての役割を果たすためには、ある
程度以上の添加量が必要である。このため、高い高率放
電特性が得られるようにするためには、表面を還元した
酸化コバルト粉末の添加量を０．１重量％以上とするこ
とが望ましい。また、表面を還元した酸化コバルトの添
加量が多いほど高率放電特性は向上するが、添加量が増
えるにしたがって水素吸蔵合金電極に含まれる水素吸蔵
合金の量が減るため、表面を還元した酸化コバルトの添
加量は１０重量％以下であることが望ましい。[0030] The role of the catalyst is effective even when the amount of cobalt oxide added is small, but a certain amount or more is required for the metal cobalt on the surface to function as a conductive agent. It is. For this reason, in order to obtain high high-rate discharge characteristics, it is desirable that the addition amount of the surface-reduced cobalt oxide powder be 0.1% by weight or more. In addition, the higher the amount of cobalt oxide whose surface is reduced, the higher the high-rate discharge characteristics are. However, as the amount of addition increases, the amount of hydrogen storage alloy contained in the hydrogen storage alloy electrode decreases. The addition amount of cobalt is desirably 10% by weight or less.
【００３１】７．コバルト化合物の平均粒径の検討 ついで、水素吸蔵合金電極に添加する酸化コバルトの平
均粒径を種々に変えて、酸化コバルトの平均粒径につい
て検討した。 （１）実施例８〜１４ 上述の実施例１と同様に作製した水素吸蔵合金粉末に、
上述の実施例１と同様に水素吸蔵合金ペーストを作製し
た後、この水素吸蔵合金ペーストに、上述の実施例１と
同様にして作製した表面を還元した二価の酸化コバルト
粉末の平均粒径を０．１μｍ，１μｍ，５μｍ，１０μ
ｍ，２５μｍ，３０μｍ，４０μｍに変えたこと以外は
上述の実施例１と同様にして、水素吸蔵合金粉末に対し
てそれぞれ１．０重量％添加し、混合して水素吸蔵合金
電極を作製した。7. Examination of Average Particle Size of Cobalt Compound Next, the average particle size of cobalt oxide added to the hydrogen storage alloy electrode was changed variously, and the average particle size of cobalt oxide was examined. (1) Examples 8 to 14 The hydrogen storage alloy powder produced in the same manner as in Example 1
After preparing the hydrogen-absorbing alloy paste in the same manner as in Example 1 described above, the average particle diameter of the surface-reduced divalent cobalt oxide powder prepared in the same manner as in Example 1 was determined. 0.1 μm, 1 μm, 5 μm, 10 μ
In the same manner as in Example 1 except that m, 25 μm, 30 μm, and 40 μm were used, 1.0% by weight was added to the hydrogen storage alloy powder and mixed to prepare a hydrogen storage alloy electrode.
【００３２】ここで、粒径が０．１μｍの表面を還元し
た二価の酸化コバルト粉末を添加したものを実施例８の
水素吸蔵合金電極ｈとし、１μｍのものを実施例９の水
素吸蔵合金電極ｉとし、５μｍのものを実施例１０の水
素吸蔵合金電極ｊとし、１０μｍのものを実施例１１の
水素吸蔵合金電極ｋとし、２５μｍのものを実施例１２
の水素吸蔵合金電極ｌとし、３０μｍのものを実施例１
３の水素吸蔵合金電極ｍとし、４０μｍのものを実施例
１４の水素吸蔵合金電極ｎとした。なお、平均粒径の異
なる表面を還元した酸化コバルト粉末は、出発物質とし
ての二価の酸化バルトを粉砕し、分級することによって
調整した。Here, a hydrogen-absorbing alloy electrode h of Example 8 was prepared by adding divalent cobalt oxide powder whose surface was reduced to a particle diameter of 0.1 μm. The electrode i was 5 μm, the hydrogen storage alloy electrode j of Example 10 was used, the electrode 10 μm was the hydrogen storage alloy electrode k of Example 11, and the electrode 25 μm was Example 12.
Example 1 used as a hydrogen storage alloy electrode 1 having a thickness of 30 μm
The hydrogen storage alloy electrode m of No. 3 and the hydrogen storage alloy electrode n of Example 14 were 40 μm. Note that the cobalt oxide powder whose surfaces having different average particle diameters were reduced was prepared by pulverizing and classifying divalent baltic oxide as a starting material.
【００３３】（２）放電容量比 これらの各水素吸蔵合金電極ｈ，ｉ，ｊ，ｋ，ｌ，ｍ，
ｎを用いて、上述の実施例１と同様にしてニッケル−水
素蓄電池を作製し、上述と同様に充放電試験を行い、１
Ｃ（１０００ｍＡ）放電時の放電容量（１Ｃ放電容量）
に対する４Ｃ（４０００ｍＡ）放電時の放電容量（４Ｃ
放電容量）の比を求めると、下記の表３に示すような結
果となった。なお、水素吸蔵合金電極ｈを用いたニッケ
ル−水素蓄電池を実施例８の電池Ｈとし、水素吸蔵合金
電極ｉを用いたニッケル−水素蓄電池を実施例９の電池
Ｉとし、水素吸蔵合金電極ｊを用いたニッケル−水素蓄
電池を実施例１０の電池Ｊとし、水素吸蔵合金電極ｋを
用いたニッケル−水素蓄電池を実施例１１の電池Ｋと
し、水素吸蔵合金電極ｌを用いたニッケル−水素蓄電池
を実施例１２の電池Ｌとし、水素吸蔵合金電極ｍを用い
たニッケル−水素蓄電池を実施例１３の電池Ｍとし、水
素吸蔵合金電極ｎを用いたニッケル−水素蓄電池を実施
例１４の電池Ｎとした。(2) Discharge capacity ratio Each of these hydrogen storage alloy electrodes h, i, j, k, l, m,
n, a nickel-hydrogen storage battery was fabricated in the same manner as in Example 1 described above, and a charge / discharge test was performed
Discharge capacity during C (1000 mA) discharge (1 C discharge capacity)
Discharge capacity at 4C (4000 mA) discharge (4C
When the ratio of (discharge capacity) was determined, the results were as shown in Table 3 below. The nickel-hydrogen storage battery using the hydrogen storage alloy electrode h is referred to as a battery H of Example 8, the nickel-hydrogen storage battery using the hydrogen storage alloy electrode i is referred to as a battery I of Example 9, and the hydrogen storage alloy electrode j is referred to as a battery I. The nickel-hydrogen storage battery used was battery J of Example 10, the nickel-hydrogen storage battery using the hydrogen storage alloy electrode k was battery B of Example 11, and the nickel-hydrogen storage battery using the hydrogen storage alloy electrode l was implemented. As the battery L of Example 12, a nickel-hydrogen storage battery using the hydrogen storage alloy electrode m was referred to as Battery M of Example 13, and a nickel-hydrogen storage battery using the hydrogen storage alloy electrode n was referred to as Battery N of Example 14.
【００３４】[0034]
【表３】 [Table 3]
【００３５】上記表３から明らかなように、電池Ａおよ
び各電池Ｈ〜Ｎの１Ｃ放電時の電池容量はいずれも９５
０ｍＡｈであった。また、表面を還元した酸化コバルト
粉末の平均粒径が小さいほど高率放電特性に効果がある
ことが分かる。特に、平均粒径が０．１μｍでは、放電
容量比は０．９６と高い値を示した。これは粒子径が小
さいほど、酸化コバルトが水素吸蔵合金電極中に均一に
分散し、導電剤として優れた効果が得られためである。
また、還元された後のコバルト金属の比表面積が大きい
ことから、水素吸蔵合金表面における電気化学反応の反
応面積を拡げる効果もあったと考えられる。As apparent from Table 3, the battery capacity of each of the battery A and each of the batteries H to N at the time of 1C discharge is 95%.
It was 0 mAh. Also, it can be seen that the smaller the average particle size of the surface-reduced cobalt oxide powder, the more effective the high-rate discharge characteristics. In particular, when the average particle size was 0.1 μm, the discharge capacity ratio showed a high value of 0.96. This is because, as the particle diameter is smaller, cobalt oxide is more uniformly dispersed in the hydrogen storage alloy electrode, and an excellent effect as a conductive agent is obtained.
Further, since the specific surface area of the cobalt metal after the reduction is large, it is considered that there was also an effect of increasing the reaction area of the electrochemical reaction on the surface of the hydrogen storage alloy.
【００３６】一方、表面を還元した酸化コバルト粉末の
平均粒径が大きくなると、導電剤としての効果も小さく
なり、比表面積も小さくなることから高率放電特性を向
上させる効果も小さくなったと考えられる。このことか
ら、水素吸蔵合金電極に添加される表面を還元した酸化
コバルト粉末の平均粒径は小さければ小さい程良いが、
０．１μｍ以下の微粒子は通常の方法では安価に製造す
ることができないことから、その平均粒径は０．１μｍ
〜３０μｍが望ましい。On the other hand, when the average particle diameter of the surface-reduced cobalt oxide powder increases, the effect as a conductive agent decreases, and the specific surface area also decreases. Therefore, it is considered that the effect of improving high-rate discharge characteristics also decreases. . From this, the smaller the average particle size of the cobalt oxide powder reduced surface added to the hydrogen storage alloy electrode, the better,
Since fine particles of 0.1 μm or less cannot be produced at low cost by ordinary methods, the average particle size is 0.1 μm.
-30 μm is desirable.
【００３７】上述したように、本発明の水素吸蔵合金電
極においては、大部分の酸化コバルトが不活性な四三酸
化コバルト（Ｃｏ3Ｏ4）にならずに金属コバルトに還元
される。また、蓄電池中で酸化コバルトは電解液中に一
部が溶出し、初期の充電時にこの溶出したコバルトイオ
ンが水素吸蔵合金表面で還元される。また、溶出しなか
った酸化コバルトも水素吸蔵合金から直接供給される電
子によって直接還元される。これらの還元されたコバル
トによって、水素吸蔵合金粒子間に導電ネットワークが
形成され、水素吸蔵合金粒子間の電気的抵抗を低下させ
ることができる。さらに、この金属コバルトは電極反応
促進のための触媒としての役割も果たすので、高率放電
特性に極めて優れたニッケル−水素蓄電池が得られる。As described above, in the hydrogen storage alloy electrode of the present invention, most of the cobalt oxide is reduced to metallic cobalt, instead of being inactive cobalt trioxide (Co 3 O 4 ). In the storage battery, cobalt oxide is partially eluted into the electrolytic solution, and at the time of initial charging, the eluted cobalt ions are reduced on the surface of the hydrogen storage alloy. Further, the undissolved cobalt oxide is also directly reduced by the electrons directly supplied from the hydrogen storage alloy. With these reduced cobalt, a conductive network is formed between the hydrogen storage alloy particles, and the electrical resistance between the hydrogen storage alloy particles can be reduced. Further, since the metal cobalt also plays a role as a catalyst for accelerating the electrode reaction, a nickel-hydrogen storage battery having extremely excellent high-rate discharge characteristics can be obtained.
【００３８】なお、上述の実施形態においては水素吸蔵
合金としてＭｍＮｉ3.1ＣｏO.8Ａｌ 0.4ＭｎO.7で表され
る水素吸蔵合金を用いる例について説明したが、水素吸
蔵合金としてはＴｉ−Ｎｉ系あるいはＬａ（もしくはＭ
ｍ）−Ｎｉ系の多元合金から適宜選択して使用すること
ができる。また、上述の実施形態においては、正極とし
て焼結式ニッケル電極を用いる例について説明したが、
正極としては焼結式ニッケル電極に限らず、非焼結式ニ
ッケル電極を用いても良い。In the above-described embodiment, the hydrogen storage is performed.
MmNi as alloy3.1CoO.8Al 0.4MnO.7Represented by
An example using a hydrogen storage alloy has been described.
Ti-Ni or La (or M
m) Use by appropriately selecting from -Ni-based multi-element alloys
Can be. In the above embodiment, the positive electrode is used.
Although an example using a sintered nickel electrode has been described,
The positive electrode is not limited to a sintered nickel electrode, but can be a non-sintered nickel electrode.
A nickel electrode may be used.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 野上 光造 大阪府守口市京阪本通２丁目５番５号 三 洋電機株式会社内 Ｆターム(参考） 5H003 AA02 AA04 BA03 BA07 BB02 BB04 BC01 BC05 BD02 BD04 5H016 AA02 BB06 BB11 EE01 EE05 HH01 HH13 5H028 BB06 BB10 EE01 EE05 EE08 EE10 HH01 HH05 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kozo Nogami 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term (reference) in Sanyo Electric Co., Ltd. 5H003 AA02 AA04 BA03 BA07 BB02 BB04 BC01 BC05 BD02 BD04 5H016 AA02 BB06 BB11 EE01 EE05 HH01 HH13 5H028 BB06 BB10 EE01 EE05 EE08 EE10 HH01 HH05
Claims (8)
吸蔵合金を備えた水素吸蔵合金電極であって、 前記水素吸蔵合金電極は少なくとも水素吸蔵合金粉末に
表面がコバルト金属で被覆されたコバルト酸化物粉末が
添加、混合されていることを特徴とする水素吸蔵合金電
極。1. A hydrogen storage alloy electrode provided with a hydrogen storage alloy that electrochemically stores and releases hydrogen, wherein the hydrogen storage alloy electrode is formed by coating a surface of at least a hydrogen storage alloy powder with cobalt metal. A hydrogen storage alloy electrode, wherein an oxide powder is added and mixed.
バルト酸化物粉末の添加量は前記水素吸蔵合金粉末重量
に対して０．１重量％以上で１０重量％以下であること
を特徴とする請求項１に記載の水素吸蔵合金電極。2. The amount of the cobalt oxide powder whose surface is coated with cobalt metal is 0.1% by weight or more and 10% by weight or less based on the weight of the hydrogen storage alloy powder. Item 2. A hydrogen storage alloy electrode according to Item 1.
バルト酸化物粉末の平均粒径は０．１μｍ以上で３０μ
ｍ以下であることを特徴とする請求項１または請求項２
に記載の水素吸蔵合金電極。3. An average particle diameter of the cobalt oxide powder whose surface is coated with cobalt metal is 0.1 μm or more and 30 μm or more.
m or less than m.
5. The hydrogen storage alloy electrode according to item 1.
バルト酸化物粉末はコバルト酸化物粉末が水素化還元さ
れたものであることを特徴とする請求項１から請求項３
のいずれかに記載の水素吸蔵合金電極。4. The cobalt oxide powder whose surface is coated with cobalt metal is obtained by hydrogenating and reducing cobalt oxide powder.
A hydrogen storage alloy electrode according to any one of the above.
吸蔵合金を主成分とする水素吸蔵合金電極と、水酸化ニ
ッケルを主成分とするニッケル電極とを備えたニッケル
・水素蓄電池であって、 前記水素吸蔵合金電極は少なくとも水素吸蔵合金粉末に
表面がコバルト金属で被覆されたコバルト酸化物粉末が
添加、混合されていることを特徴とするニッケル・水素
蓄電池。5. A nickel-metal hydride storage battery comprising: a hydrogen storage alloy electrode mainly composed of a hydrogen storage alloy electrochemically storing and releasing hydrogen; and a nickel electrode mainly composed of nickel hydroxide. A nickel-metal hydride storage battery, wherein the hydrogen storage alloy electrode is obtained by adding and mixing at least a hydrogen storage alloy powder with a cobalt oxide powder whose surface is coated with cobalt metal.
バルト酸化物粉末の添加量は前記水素吸蔵合金粉末重量
に対して０．１重量％以上で１０重量％以下であること
を特徴とする請求項５に記載のニッケル・水素蓄電池。6. An addition amount of the cobalt oxide powder whose surface is coated with cobalt metal is not less than 0.1% by weight and not more than 10% by weight based on the weight of the hydrogen storage alloy powder. Item 6. The nickel-metal hydride storage battery according to Item 5.
バルト酸化物粉末の平均粒径は０．１μｍ以上で３０μ
ｍ以下であることを特徴とする請求項５または請求項６
に記載のニッケル・水素蓄電池。7. An average particle diameter of the cobalt oxide powder whose surface is coated with cobalt metal is 0.1 μm or more and 30 μm or more.
m or less than m.
2. A nickel-metal hydride storage battery according to claim 1.
バルト酸化物粉末はコバルト酸化物紛末が水素化還元さ
れたものであることを特徴とする請求項５から請求項７
のいずれかに記載のニッケル・水素蓄電池。8. The cobalt oxide powder whose surface is coated with cobalt metal is obtained by reducing cobalt oxide powder by hydrogenation.
The nickel-metal hydride storage battery according to any one of the above.
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|---|---|---|---|
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07051699A JP3653412B2 (en) | 1999-03-16 | 1999-03-16 | Hydrogen storage alloy electrode and nickel-hydrogen storage battery using this electrode |
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| Publication Number | Publication Date |
|---|---|
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| JP3653412B2 JP3653412B2 (en) | 2005-05-25 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2003092113A1 (en) * | 2000-10-31 | 2003-11-06 | Kawasaki Jukogyo Kabushiki Kaisha | Battery |
-
1999
- 1999-03-16 JP JP07051699A patent/JP3653412B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2003092113A1 (en) * | 2000-10-31 | 2003-11-06 | Kawasaki Jukogyo Kabushiki Kaisha | Battery |
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| Publication number | Publication date |
|---|---|
| JP3653412B2 (en) | 2005-05-25 |
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