JP3432870B2 - Method for producing metal hydride electrode - Google Patents
Method for producing metal hydride electrodeInfo
- Publication number
- JP3432870B2 JP3432870B2 JP29873193A JP29873193A JP3432870B2 JP 3432870 B2 JP3432870 B2 JP 3432870B2 JP 29873193 A JP29873193 A JP 29873193A JP 29873193 A JP29873193 A JP 29873193A JP 3432870 B2 JP3432870 B2 JP 3432870B2
- Authority
- JP
- Japan
- Prior art keywords
- hydrogen storage
- storage alloy
- electrode
- battery
- hydrogen
- 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.)
- Expired - Fee Related
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Description
【０００１】[0001]
【従来の技術】従来から広く用いられている蓄電池とし
ては、鉛蓄電池、及び、ニッケル−カドミウム電池があ
る。しかし、近年、これら電池より軽量で且つ高容量と
なる可能性があるということで、特に常圧で負極活物質
である水素を可逆的に吸蔵、及び、放出することのでき
る水素吸蔵合金を負極に用い、水酸化ニッケルなどの金
属酸化物を正極活物質とする電極を正極に用いた金属−
水素アルカリ蓄電池が注目されている。2. Description of the Related Art Lead-acid batteries and nickel-cadmium batteries have been widely used as storage batteries. However, in recent years, since it is possible to have a lighter weight and a higher capacity than these batteries, a negative electrode is a hydrogen storage alloy capable of reversibly storing and releasing hydrogen, which is a negative electrode active material, at normal pressure. And a metal oxide having a metal oxide such as nickel hydroxide as a positive electrode active material is used as a positive electrode.
Hydrogen alkaline storage batteries are receiving attention.
【０００２】従来から、この金属−水素アルカリ蓄電池
の電池特性を向上させるために、様々な表面の改質処理
が施された水素吸蔵合金が、負極材料として用いられて
いる。例えば、特公平４−７９４７４号公報では、水素
吸蔵合金の表面をアルカリ水溶液を用いて処理を行って
いる。この方法によればアルカリ処理を行うことによ
り、水素吸蔵合金表面にニッケルリッチな層が形成され
る。Conventionally, in order to improve the battery characteristics of this metal-hydrogen alkaline storage battery, a hydrogen storage alloy having various surface modification treatments has been used as a negative electrode material. For example, in Japanese Examined Patent Publication No. 4-79474, the surface of the hydrogen storage alloy is treated with an alkaline aqueous solution. According to this method, a nickel-rich layer is formed on the surface of the hydrogen storage alloy by performing the alkali treatment.
【０００３】ニッケルは酸素の還元反応の触媒となるた
め、ニッケルリッチな層が水素吸蔵合金表面に形成され
ることで、過充電時の正極から放出される、酸素ガスの
吸収が合金表面で円滑に進行するために電池内圧の上昇
が抑制され充放電サイクル特性が向上する。また、特開
平３−９８２５９号公報では、水素吸蔵合金を６０℃以
上の加熱水で表面処理をする方法が開示されている。こ
の方法で処理を行った水素吸蔵合金も表面にニッケルリ
ッチな層が形成され、上記と同様に充放電サイクル特性
が向上する。Since nickel serves as a catalyst for the reduction reaction of oxygen, a nickel-rich layer is formed on the surface of the hydrogen storage alloy, so that the oxygen gas released from the positive electrode during overcharge is smoothly absorbed on the alloy surface. As a result, the increase in battery internal pressure is suppressed, and the charge / discharge cycle characteristics are improved. Further, JP-A-3-98259 discloses a method of surface-treating a hydrogen storage alloy with heated water at 60 ° C. or higher. Also in the hydrogen storage alloy treated by this method, a nickel-rich layer is formed on the surface, and the charge / discharge cycle characteristics are improved in the same manner as above.
【０００４】ところが、これらの表面処理合金は、酸素
ガス吸収能が優れているので、充放電サイクル寿命は優
れているが、水素吸蔵合金表面に水酸化物が形成される
ために、水素吸蔵合金間の接触抵抗が大きく、活性化が
悪く、とくに充放電サイクル初期の高率充放電特性及び
低温放電特性が悪いという問題があった。このような、
充放電サイクル初期の高率放電特性や、低温放電特性を
向上させるための方法として以下に示すような方法が提
案されている。
特開平３−１５２８６８号公報に開示された方法
この方法では、合金の初期活性化を阻害する緻密な酸素
膜を、酸処理により除去してから、アルカリ処理を施す
ことにより高率充放電にも優れ、且つ、ガス吸収能の優
れた金属水素化物電極が実現できることが開示されてい
る。
特開平５−１３５７９７号公報に開示された方法
この方法では、還元剤である水素化ホウ素ナトリウム等
の可溶性水素化物を添加したアルカリ水溶液で負極を処
理することにより、活性化に優れ、電池内圧上昇が抑制
された電極が実現できることが開示されている。このよ
うに、還元剤を添加することによって活性度が向上する
のは、還元剤から発生した水素が一部水素に吸蔵される
ためであると考えられる。However, these surface-treated alloys are excellent in oxygen gas absorption ability, and thus are excellent in charge / discharge cycle life. However, since hydroxide is formed on the surface of the hydrogen storage alloy, the hydrogen storage alloy is formed. There is a problem that the contact resistance between them is large and the activation is poor, and especially the high rate charge / discharge characteristics and the low temperature discharge characteristics at the beginning of the charge / discharge cycle are poor. like this,
The following methods have been proposed as methods for improving the high rate discharge characteristics at the initial stage of the charge / discharge cycle and the low temperature discharge characteristics. Method disclosed in JP-A-3-152868 In this method, a dense oxygen film that inhibits the initial activation of the alloy is removed by acid treatment, and then alkali treatment is performed to achieve high rate charge / discharge. It is disclosed that a metal hydride electrode having excellent gas absorption ability can be realized. Method disclosed in JP-A-5-135797 In this method, by treating the negative electrode with an alkaline aqueous solution to which a soluble hydride such as sodium borohydride, which is a reducing agent, is treated, the activation is excellent and the battery internal pressure rises. It is disclosed that an electrode in which is suppressed can be realized. As described above, it is considered that the reason why the activity is improved by adding the reducing agent is that the hydrogen generated from the reducing agent is partially occluded in the hydrogen.
【０００５】[0005]
【発明が解決しようとする課題】ところが、上記した
、の処理方法でも、以下に示すような問題を生じ
る。
特開平３−１５２８６８号公報に開示された方法の問
題点
この処理方法を用いた場合、酸処理の後にアルカリ処理
を施すと、酸処理のみの場合と比較して活性度が低下
し、低温放電特性は十分なものではなく、さらなる向上
が必要であるという問題があった。
特開平５−１３５７９７号公報に開示された方法の問
題点
この方法についても、活性度の向上は十分ではなくさら
なる向上が望まれている。However, even with the above processing method, the following problems occur. Problems of the method disclosed in JP-A-3-152868. When this treatment method is used, when the acid treatment is followed by the alkali treatment, the activity is lowered as compared with the case of only the acid treatment, and low temperature discharge is performed. There is a problem that the characteristics are not sufficient and further improvement is necessary. Problems of the method disclosed in Japanese Patent Laid-Open No. 135797/1993 Even in this method, the activity is not sufficiently improved and further improvement is desired.
【０００６】本発明は、上記問題点に鑑み行なわれたも
のであり、充放電サイクル寿命が長く、しかも活性度の
高い金属水素化物電極の製造方法を提供することを目的
とする。The present invention has been made in view of the above problems, and an object thereof is to provide a method for producing a metal hydride electrode having a long charge / discharge cycle life and high activity.
【０００７】[0007]
【課題を解決するための手段】上記目的を達成するため
に、本発明では、水素吸蔵合金を負極材料に用いた金属
水素化物電極の製造方法において、不均一歪みが３．５
×１０-3以下の水素吸蔵合金に対してｐＨ値が０．５〜
６．０の酸性水溶液に還元剤を添加した水溶液により表
面処理を行うステップを有することを特徴とする。In order to achieve the above object, in the present invention, in a method for producing a metal hydride electrode using a hydrogen storage alloy as a negative electrode material, a nonuniform strain is 3.5.
PH value of 0.5 to 10 for hydrogen storage alloys of 10 −3 or less
The method is characterized by having a step of performing surface treatment with an aqueous solution obtained by adding a reducing agent to the acidic aqueous solution of 6.0.
【０００８】また、上記酸性水溶液により表面処理を行
うステップが水素吸蔵合金鋳塊の粉砕時に行われること
を特徴とする。また、上記酸性水溶液により表面処理を
行うステップが電極を作製する前の水素吸蔵合金粉末に
対して行われることを特徴とする。また、上記酸性水溶
液による表面処理が、電極に対して行われることを特徴
とする。Further, the step of performing the surface treatment with the acidic aqueous solution is performed when the hydrogen storage alloy ingot is pulverized. Further, the step of performing the surface treatment with the acidic aqueous solution is performed on the hydrogen storage alloy powder before producing the electrode. Further, the surface treatment with the acidic aqueous solution is performed on the electrode.
【０００９】[0009]
【作用】上記のようなステップを有する製造を行なうこ
とによって以下に示すような作用が起こる。水素吸蔵合
金をｐＨ値が０．５〜６．０の酸性水溶液により表面処
理を施すと、水素吸蔵合金の表面が水素を発生しながら
溶解する。この合金の溶解により発生した水素は、再
度、水素吸蔵合金に吸蔵される。水素吸蔵合金に水素が
吸収される際に、金属に亀裂が生じ、新たな活性面が生
成され合金の活性度が向上する。このように、合金の活
性度が向上すると、高率放電特性、及び、低温放電特性
は上昇する。By carrying out the manufacturing including the steps as described above, the following operations occur. When the hydrogen storage alloy is surface-treated with an acidic aqueous solution having a pH value of 0.5 to 6.0, the surface of the hydrogen storage alloy dissolves while generating hydrogen. Hydrogen generated by the melting of this alloy is again stored in the hydrogen storage alloy. When hydrogen is absorbed by the hydrogen storage alloy, a crack is generated in the metal, a new active surface is generated, and the activity of the alloy is improved. As described above, when the activity of the alloy is improved, the high rate discharge characteristic and the low temperature discharge characteristic are improved.
【００１０】また、還元剤から発生する水素の吸収も起
こり、この水素も合金に吸収される。本発明の場合、合
金及び還元剤から水素が発生し、しかも、酸性溶液中に
還元剤が加えられているので、還元剤の水素発生は起こ
り易くなっている。従って、大量の水素が発生すること
になり、合金の水素吸蔵が行なわれやすくなり、合金の
活性度は上昇する。Further, the hydrogen generated from the reducing agent is also absorbed, and this hydrogen is also absorbed by the alloy. In the case of the present invention, hydrogen is generated from the alloy and the reducing agent, and moreover, since the reducing agent is added to the acidic solution, hydrogen is easily generated from the reducing agent. Therefore, a large amount of hydrogen is generated, the hydrogen is easily absorbed in the alloy, and the activity of the alloy is increased.
【００１１】また、本発明の水素吸蔵合金は、不均一歪
みが３．５×１０-3以下であるため、結晶性に優れてお
り、酸処理をおこなっても大きな割れが生じることはな
く、また、充放電サイクルを進行させた際も微粉化が進
行し過ぎることはなく放電サイクル寿命が短くなること
はない。さらに、水素吸蔵合金の主成分であるニッケル
よりも他の合金の成分の方が酸性領域での溶解度が大き
く、酸に浸漬することによって選択的に溶解し、水素吸
蔵合金表面にはニッケルリッチな層が形成される。ニッ
ケルは水素吸蔵合金の酸素ガス吸収の触媒になるため
に、このニッケルリッチ層において過充電時の酸素ガス
吸収が円滑に進行し、電池内圧の上昇が抑制される。電
池内圧の上昇の抑制は安全弁からのリークを防ぎ、充放
電サイクル寿命の向上に効果がある。Since the hydrogen storage alloy of the present invention has a non-uniform strain of 3.5 × 10 −3 or less, it has excellent crystallinity and does not cause large cracks even when subjected to acid treatment. Further, even when the charge / discharge cycle is advanced, pulverization does not proceed too much, and the discharge cycle life is not shortened. Further, the components of the other alloys have a higher solubility in the acidic region than nickel, which is the main component of the hydrogen storage alloy, and are selectively dissolved by immersion in acid, and the surface of the hydrogen storage alloy is rich in nickel. A layer is formed. Since nickel serves as a catalyst for absorbing oxygen gas in the hydrogen storage alloy, absorption of oxygen gas during overcharging proceeds smoothly in this nickel-rich layer, and increase in battery internal pressure is suppressed. The suppression of the rise in battery internal pressure is effective in preventing leakage from the safety valve and improving the charge / discharge cycle life.
【００１２】尚、上記した不均一歪みとは、以下のよう
に定義される値である。ラウエカメラ等でデバイ環を測
定した際に、このデバイ環がブロードになる現象の原因
の１つであって、下記数１によって定義される。The above-mentioned non-uniform strain is a value defined as follows. This is one of the causes of the phenomenon that the Debye ring becomes broad when it is measured with a Laue camera or the like, and it is defined by the following formula 1.
【００１３】[0013]
【数１】 [Equation 1]
【００１４】[0014]
【実施例】本発明の一例に係る実施例について以下に説
明を行う。
（実施例１）
〔電水素吸蔵合金極の作製方法〕先ず、以下のようにし
て、電極用水素吸蔵合金粉末を作製した。EXAMPLES Examples according to an example of the present invention will be described below. (Example 1) [Production method of electrohydrogen storage alloy electrode] First, a hydrogen storage alloy powder for an electrode was produced as follows.
【００１５】市販のミッシュメタルＭｍ（Ｌａ、Ｃｅ、
Ｎｄ、Ｐｒ等の希土類元素の混合物）、Ｎｉ、Ｃｏ、及
び、Ｍｎを用い元素比でＭｍ：Ｎｉ：Ｃｏ：Ａｌ：Ｍｎ
が１：３．４：０．８：０．２：０．６となるように秤
量して混合した。次に、この混合物をアルゴン不活性雰
囲気下の高周波溶解炉にて溶解し、冷却を行って、Ｍｍ
Ｎｉ3.4 Ｃｏ0.8 Ａｌ0.2 Ｍｎ0.6 で示される水素吸蔵
合金鋳塊を作製した。この時点での水素吸蔵合金の不均
一歪みは５．４×１０-3であり、この水素吸蔵合金鋳塊
を以下水素吸蔵合金鋳塊（Ｍ1 ）と称する。Commercially available misch metal Mm (La, Ce,
A mixture of rare earth elements such as Nd and Pr), Ni, Co, and Mn are used, and the element ratio is Mm: Ni: Co: Al: Mn.
Were weighed and mixed so that the ratio was 1: 3.4: 0.8: 0.2: 0.6. Next, this mixture is melted in a high-frequency melting furnace under an argon-inert atmosphere and cooled to obtain Mm.
A hydrogen storage alloy ingot represented by Ni 3.4 Co 0.8 Al 0.2 Mn 0.6 was produced. The non-uniform strain of the hydrogen storage alloy at this time is 5.4 × 10 −3 , and this hydrogen storage alloy ingot is hereinafter referred to as hydrogen storage alloy ingot (M 1 ).
【００１６】次に、上記水素吸蔵合金鋳塊（Ｍ1 ）を不
活性ガス中、１０００℃で８時間アニール処理を行う。
アニール処理を行なった後の水素吸蔵合金鋳塊の不均一
歪みは２．５×１０-3であり、この水素吸蔵合金粉末を
以下水素吸蔵合金鋳塊（Ｍ2）と称する。この水素吸蔵
合金鋳塊（Ｍ2 ）を、不活性ガス中で、一旦粒径５００
μｍ以下に粉砕し、さらにｐＨ＝１．０の塩酸に対して
還元剤である水素化ホウ素ナトリウムを０．３％溶解さ
せた溶液中で、ボールミルを用いて平均粒径１５０μｍ
以下になるように粉砕した。粉砕後、イオン交換水で十
分洗浄を行い、乾燥させて、電極用水素吸蔵合金粉末を
作製した。尚、粉砕時の処理温度は、室温である。Next, the hydrogen-absorbing alloy ingot (M 1 ) is annealed in an inert gas at 1000 ° C. for 8 hours.
The non-uniform strain of the hydrogen storage alloy ingot after the annealing treatment is 2.5 × 10 −3 , and this hydrogen storage alloy powder is hereinafter referred to as hydrogen storage alloy ingot (M 2 ). This hydrogen-absorbing alloy ingot (M 2 ) was once treated with an inert gas to a particle size of 500
Average particle size of 150 μm using a ball mill in a solution in which 0.3% of sodium borohydride as a reducing agent is dissolved in hydrochloric acid having a pH of 1.0
It was crushed to the following. After pulverization, it was thoroughly washed with ion-exchanged water and dried to prepare a hydrogen storage alloy powder for electrodes. The processing temperature during pulverization is room temperature.
【００１７】このようにして作製した電極用水素吸蔵合
金粉末に対して、結着剤であるポリテトラフルオロエチ
レン粉末を５重量％加えて混練し、ペーストを作製し
た。このペーストをパンチングメタルからなる集電体の
両面に圧着後、プレスして金属水素化物電極を作製し
た。
〔電池の組立〕上記のように作製された金属水素化物電
極と、公知の焼結式ニッケル極とを、不織布からなるセ
パレータを介して捲回し、電極群を作製した。この電極
群を外装缶に挿入し、さらに３０重量％の水酸化カリウ
ム水溶液を上記外装缶に注液した後、外装缶を密閉する
ことにより理論容量が１０００ｍＡｈの円筒型ニッケル
−水素蓄電池を作製した。5% by weight of polytetrafluoroethylene powder as a binder was added to the hydrogen storage alloy powder for an electrode thus prepared and kneaded to prepare a paste. This paste was pressure-bonded to both sides of a current collector made of punching metal and then pressed to produce a metal hydride electrode. [Assembly of Battery] The metal hydride electrode produced as described above and a known sintered nickel electrode were wound with a separator made of a non-woven fabric interposed therebetween to produce an electrode group. This electrode group was inserted into an outer can, and a 30 wt% potassium hydroxide aqueous solution was further poured into the outer can, and then the outer can was sealed to produce a cylindrical nickel-hydrogen storage battery having a theoretical capacity of 1000 mAh. .
【００１８】このようにして作製された電池を以下（Ａ
1 ）電池と称する。
（実施例２）上記水素吸蔵合金鋳塊（Ｍ2 ）を不活性ガ
ス中で、平均粒径が１５０μｍ以下になるように粉砕
し、粉砕された水素吸蔵合金を、ｐＨ＝１．０の塩酸に
対して水素化ホウ素ナトリウムを０．３％溶解させた溶
液中に２０分間浸漬し、その後、イオン交換水で十分洗
浄を行い、乾燥させて、電極用水素吸蔵合金粉末を作製
した。 このように作製した電極用水素吸蔵合金粉末を
用いて上記実施例１と同様に電極及び電池を作製した。The battery produced in this manner is described below (A
1 ) Called battery. (Example 2) The above hydrogen storage alloy ingot (M 2 ) was pulverized in an inert gas so that the average particle diameter was 150 μm or less, and the pulverized hydrogen storage alloy was treated with hydrochloric acid having a pH of 1.0. On the other hand, it was immersed in a solution in which sodium borohydride was dissolved by 0.3% for 20 minutes, then sufficiently washed with ion-exchanged water and dried to prepare a hydrogen storage alloy powder for electrodes. An electrode and a battery were produced in the same manner as in Example 1 using the hydrogen storage alloy powder for an electrode thus produced.
【００１９】このように作製した電池を、以下（Ａ2 ）
電池と称する。
（比較例１）合金の粉砕時に用いる処理溶液としてｐＨ
＝１．０の塩酸に対して水素化ホウ素ナトリウムを０．
３％溶解させた溶液のかわりに、０．３％水素化ホウ素
ナトリウム水溶液を用いた以外は、上記実施例１と同様
に、電極用水素吸蔵合金粉末を作製し、当該電極用水素
吸蔵合金粉末を用いて、上記実施例１と同様にして電極
及び、電池の作製を行った。The battery produced in this manner is described below (A 2 )
It is called a battery. (Comparative Example 1) pH as a treatment solution used when pulverizing an alloy
= 1.0 for sodium borohydride against hydrochloric acid of 1.0.
A hydrogen storage alloy powder for an electrode was prepared in the same manner as in Example 1 except that a 0.3% sodium borohydride aqueous solution was used instead of the 3% dissolved solution. Using the above, an electrode and a battery were produced in the same manner as in Example 1 above.
【００２０】このように作製した電池を以下（Ｘ1 ）電
池と称する。
（比較例２）合金の粉砕時に用いる処理溶液として、ｐ
Ｈ＝１．０の塩酸に対して水素化ホウ素ナトリウムを
０．３％溶解させた溶液のかわりに、ｐＨ＝１の塩酸を
用いた以外は、上記実施例１と同様に、電極用水素吸蔵
合金粉末を作製し、当該電極用水素吸蔵合金粉末を用い
て、上記実施例１と同様にして電極及び、電池の作製を
行った。The battery thus manufactured is hereinafter referred to as a (X 1 ) battery. (Comparative Example 2) As a treatment solution used when pulverizing an alloy, p
Hydrogen storage for electrodes was carried out in the same manner as in Example 1 except that hydrochloric acid having a pH of 1 was used in place of a solution prepared by dissolving 0.3% of sodium borohydride in hydrochloric acid having a H of 1.0. An alloy powder was prepared, and an electrode and a battery were prepared in the same manner as in Example 1 using the hydrogen storage alloy powder for an electrode.
【００２１】このように作製した電池を以下（Ｘ2 ）電
池と称する。
（比較例３）上記水素吸蔵合金粉末（Ｍ1 ）に対してア
ニール処理を行わないこと以外は、上記実施例１と同様
に電極用水素吸蔵合金粉末を作製し、当該電極用水素吸
蔵合金粉末を用いて、上記実施例１と同様にして電極及
び電池の作製を行った。The battery thus produced is hereinafter referred to as a (X 2 ) battery. (Comparative Example 3) A hydrogen storage alloy powder for electrodes was prepared in the same manner as in Example 1 except that the hydrogen storage alloy powder (M 1 ) was not annealed. Using the above, an electrode and a battery were prepared in the same manner as in Example 1 above.
【００２２】このように作製した電池を以下（Ｘ3 ）と
称する。
（比較例４）上記水素吸蔵合金粉末（Ｍ1 ）に対してア
ニール処理を行わなわず、さらに、合金の粉砕時に用い
る処理溶液として、ｐＨ＝１．０の塩酸に対して水素化
ホウ素ナトリウムを０．３％溶解させた溶液のかわり
に、０．３％水素化ホウ素ナトリウム水溶液を用いた以
外は、上記実施例１と同様に電極用水素吸蔵合金粉末を
作製し、当該電極用水素吸蔵合金粉末を用いて、上記実
施例１と同様にして電極及び電池の作製を行った。この
ように作製した電池を以下（Ｘ4 ）電池と称する。
（比較例５）上記水素吸蔵合金粉末（Ｍ1 ）に対してア
ニール処理を行わなわず、さらに、合金の粉砕時に用い
る処理溶液として、ｐＨ＝１．０の塩酸に対して水素化
ホウ素ナトリウムを０．３％溶解させた溶液のかわり
に、ｐＨ＝１の塩酸を用いた以外は、上記実施例１と同
様に電極用水素吸蔵合金粉末を作製し、当該電極用水素
吸蔵合金粉末を用いて、上記実施例１と同様にして電極
及び電池の作製を行った。このように作製した電池を以
下（Ｘ5 ）電池と称する。
（比較例６）粉砕後の合金の浸漬処理の際の、処理溶液
として、ｐＨ＝１．０の塩酸に対して水素化ホウ素ナト
リウムを０．３％溶解させた溶液のかわりに、０．３％
水素化ホウ素ナトリウム水溶液を用いた以外は、上記実
施例２と同様に電極用水素吸蔵合金粉末を作製し、当該
電極用水素吸蔵合金粉末を用いて、上記実施例１と同様
にして電極及び電池の作製を行った。The battery thus manufactured is hereinafter referred to as (X 3 ). (Comparative Example 4) The hydrogen-absorbing alloy powder (M 1 ) was not annealed, and sodium borohydride was added to hydrochloric acid having a pH of 1.0 as a treatment solution to be used for pulverizing the alloy. A hydrogen storage alloy powder for an electrode was prepared in the same manner as in Example 1 except that a 0.3% sodium borohydride aqueous solution was used instead of the 0.3% dissolved solution. An electrode and a battery were prepared using the powder in the same manner as in Example 1 above. The battery thus manufactured is hereinafter referred to as (X 4 ) battery. (Comparative Example 5) The hydrogen-absorbing alloy powder (M 1 ) was not annealed, and sodium borohydride was added to hydrochloric acid having a pH of 1.0 as a treatment solution to be used for pulverizing the alloy. A hydrogen storage alloy powder for electrodes was prepared in the same manner as in Example 1 except that hydrochloric acid having a pH of 1 was used in place of the 0.3% dissolved solution, and the hydrogen storage alloy powder for electrodes was used. An electrode and a battery were prepared in the same manner as in Example 1 above. The battery thus produced is hereinafter referred to as (X 5 ) battery. (Comparative Example 6) In the immersion treatment of the alloy after crushing, as a treatment solution, 0.3% of sodium borohydride was dissolved in hydrochloric acid having a pH of 1.0, instead of 0.3%. %
An electrode hydrogen storage alloy powder was prepared in the same manner as in Example 2 except that an aqueous sodium borohydride solution was used, and the electrode hydrogen storage alloy powder was used in the same manner as in Example 1 above to prepare an electrode and a battery. Was prepared.
【００２３】このように作製した、電池を以下（Ｘ6 ）
電池と称する。
（比較例７）粉砕後の合金の浸漬処理の際の、処理溶液
として、ｐＨ＝１．０の塩酸に対して水素化ホウ素ナト
リウムを０．３％溶解させた溶液のかわりに、ｐＨ＝
１．０の塩酸を用いた以外は、上記実施例２と同様に電
極用水素吸蔵合金粉末を作製し、当該電極用水素吸蔵合
金粉末を用いて、上記実施例１と同様にして電極及び電
池の作製を行った。The battery produced in this way is described below (X 6 )
It is called a battery. (Comparative Example 7) Instead of a solution prepared by dissolving 0.3% of sodium borohydride in hydrochloric acid having a pH value of 1.0 as a treatment solution for dipping the alloy after grinding, pH =
An electrode hydrogen storage alloy powder was prepared in the same manner as in Example 2 except that 1.0 hydrogen chloride was used, and the electrode and battery were prepared in the same manner as in Example 1 using the hydrogen storage alloy powder for electrode. Was prepared.
【００２４】このように作製した電池を以下（Ｘ7 ）電
池と称する。
（比較例８）上記水素吸蔵合金鋳塊（Ｍ2 ）を不活性ガ
ス中で、平均粒径が１５０μｍ以下になるように粉砕
し、粉砕された水素吸蔵合金をそのまま電極用水素吸蔵
合金とし、当該電極用水素吸蔵合金粉末を用いて、上記
実施例１と同様にして電極及び電池の作製を行った。The battery thus produced is hereinafter referred to as a (X 7 ) battery. (Comparative Example 8) The hydrogen storage alloy ingot (M 2 ) was crushed in an inert gas so that the average particle size was 150 μm or less, and the crushed hydrogen storage alloy was used as it was as a hydrogen storage alloy for electrodes. Using the hydrogen storage alloy powder for electrodes, electrodes and batteries were prepared in the same manner as in Example 1 above.
【００２５】このように作製された電池を以下、
（Ｘ8 ）電池と称する。記の電池について、水素吸蔵合
金の不均一歪み、及び、合金の表面処理方法を一覧表に
したので、下記表１に示す。The battery thus produced is described below.
(X 8) is referred to as a battery. Regarding the above batteries, the non-uniform strain of the hydrogen storage alloy and the surface treatment method of the alloy are listed, which is shown in Table 1 below.
【００２６】[0026]
【表１】 [Table 1]
【００２７】（実験１）上記実施例の（Ａ1 ）、
（Ａ2 ）電池、及び比較例の（Ｘ1 ）〜（Ｘ8 ）電池を
用いて、高率放電特性、低温放電特性、充放電サイクル
寿命を調べたので、その結果を下記表２〜表４に示す。
尚、実験に先立ち、各電池に対して以下に示すような方
法で活性化を行った。(Experiment 1) (A 1 ) of the above embodiment,
High rate discharge characteristics, low temperature discharge characteristics and charge / discharge cycle life were examined using the (A 2 ) battery and the (X 1 ) to (X 8 ) batteries of Comparative Examples. The results are shown in Tables 2 to 2 below. 4 shows.
Prior to the experiment, each battery was activated by the following method.
【００２８】各電池を、１００ｍＡで１６時間充電し、
１時間休止した後、２００ｍＡで電圧が１．０Ｖになる
まで放電し、１時間休止するという充放電サイクルを室
温で３サイクル行った。このように活性化された電池に
対して行われたそれぞれの実験の条件を以下に示す。
〔高率放電特性〕室温において、１００ｍＡで１６時間
充電し、１時間休止の後、４０００ｍＡで、１．０Ｖに
なるまで放電を行い、各電池の放電容量を測定した。
〔低温放電特性〕室温において１００ｍＡで１６時間充
電し、−１０℃で３時間休止した後、−１０℃、１００
０ｍＡで１．０Ｖになるまで放電を行い、各電池の放電
容量を測定した。
〔充放電サイクル特性〕室温において、１５００ｍＡで
４８分充電をし、１時間休止の後、１５００ｍＡで１．
０Ｖになるまで放電をおこない、１時間休止するという
充放電サイクルを電池容量が５００ｍＡｈになるまで、
繰り返し行い、サイクル数を調べた。Each battery was charged at 100 mA for 16 hours,
After resting for 1 hour, discharging was performed at 200 mA until the voltage became 1.0 V, and resting for 1 hour was repeated 3 cycles at room temperature. The conditions for each of the experiments carried out on the cells thus activated are shown below. [High Rate Discharge Characteristic] At room temperature, the battery was charged at 100 mA for 16 hours, rested for 1 hour, then discharged at 4000 mA to 1.0 V, and the discharge capacity of each battery was measured. [Low-temperature discharge characteristics] Charged at 100 mA for 16 hours at room temperature, rested at -10 ° C for 3 hours, and then at -10 ° C, 100
The battery was discharged at 0 mA to 1.0 V, and the discharge capacity of each battery was measured. [Charge / Discharge Cycle Characteristics] At room temperature, the battery was charged at 1500 mA for 48 minutes, rested for 1 hour, and then at 1500 mA for 1.
Discharge until it reaches 0 V, and then perform a charge-discharge cycle of resting for 1 hour until the battery capacity reaches 500 mAh.
Repeatedly, the number of cycles was examined.
【００２９】[0029]
【表２】 [Table 2]
【００３０】[0030]
【表３】 [Table 3]
【００３１】[0031]
【表４】 [Table 4]
【００３２】高率放電特性、低温放電特性、充放電サイ
クル寿命何れについても本実施例の（Ａ1 ）、（Ａ2 ）
電池は優れた特性を示した。また、同様の表面処理を行
った（Ｘ3 ）電池の充放電サイクル寿命が短いのは、不
均一歪みが大きく、水素吸蔵の際の微粉化が進行し過ぎ
てしまい、合金の酸化による劣化が進行し、充放電サイ
クル特性が低下したものと考えられる。
（実験２）還元剤を溶解する溶液のｐＨ値と高率放電特
性との関係を調べたので、その結果を図１に示す。The high rate discharge characteristics, the low temperature discharge characteristics and the charge / discharge cycle life of (A 1 ), (A 2 )
The battery showed excellent characteristics. Further, the short charging / discharging cycle life of the (X 3 ) battery which has been subjected to the same surface treatment has a large non-uniform strain, which causes excessive pulverization at the time of hydrogen absorption and deterioration of the alloy due to oxidation. It is considered that the charging and discharging cycle characteristics progressed and the charging and discharging cycle characteristics deteriorated. (Experiment 2) The relationship between the pH value of the solution in which the reducing agent is dissolved and the high rate discharge characteristics was investigated, and the results are shown in FIG.
【００３３】この実験の実験条件は、以下に示す通りで
ある。水素吸蔵合金（Ｍ2 ）（不均一歪み２．５×１０
-3）の粉砕時に用いる処理溶液の作製時に水素化ホウ素
ナトリウムを溶解させる溶液のｐＨ値をｐＨ＝０からｐ
Ｈ＝９．０まで変化させ、上記実施例１と同様に電極、
電池の作製を行い、上記実験１の高率充放電特性の測定
と同様の条件で実験を行った。The experimental conditions of this experiment are as follows. Hydrogen storage alloy (M 2 ) (non-uniform strain 2.5 × 10
-3 ) The pH value of the solution in which sodium borohydride is dissolved at the time of preparing the treatment solution used for pulverization is from 0 to p
The electrode was changed to H = 9.0, the same as in Example 1 above,
A battery was prepared, and an experiment was performed under the same conditions as the measurement of the high rate charge / discharge characteristics in Experiment 1 above.
【００３４】尚、本実験で用いた水素化ホウ素ナトリウ
ムを溶解した溶液は、０≦ｐＨ＜７では塩酸、ｐＨ＝７
では純水、７＜ｐＨ≦９では水酸化カリウム溶液を用
い、何れの溶液に対しても水素化ホウ素ナトリウムを
０．３％溶解させた。図１から明らかなように、ｐＨ値
が０．５〜６．０の溶液に還元剤を溶解させた処理溶液
を用いた場合、良好な高率放電特性が得られた。
（実験３）還元剤を溶解する溶液のｐＨ値と充放電サイ
クル寿命との関係を調べたので、その結果を図２に示
す。The solution in which sodium borohydride was used in this experiment was hydrochloric acid at 0 ≦ pH <7, and pH = 7.
Pure water was used, and a potassium hydroxide solution was used when 7 <pH ≦ 9, and 0.3% of sodium borohydride was dissolved in each solution. As is clear from FIG. 1, good high rate discharge characteristics were obtained when a treatment solution in which a reducing agent was dissolved in a solution having a pH value of 0.5 to 6.0 was used. (Experiment 3) The relationship between the pH value of the solution in which the reducing agent is dissolved and the charge / discharge cycle life was examined. The results are shown in FIG.
【００３５】この実験の実験条件は、以下に示す通りで
ある。上記実験２の場合と同様に、水素化ホウ素ナトリ
ウムを溶解する溶液のｐＨ値をｐＨ＝０からｐＨ＝９．
０まで変化させて電極、電池を作製し、上記実験１の充
放電サイクル寿命の測定と同様の条件で実験を行った。
図２から明らかなように、ｐＨ値が０．５〜６．０の溶
液に還元剤を溶解させた処理溶液を用いた場合、良好な
充放電サイクル寿命が得られた。
（実験４）上記実験１の充放電サイクル特性の実験結果
より、（Ｘ3 ）電池は、実施例と同様の表面処理を行っ
た水素吸蔵合金を電極材料として用いているにも関わら
ず、実施例の電池と比較して充放電サイクル寿命が短い
という結果が得られた。The experimental conditions for this experiment are as follows. As in Experiment 2 above, the pH value of the solution in which sodium borohydride is dissolved ranges from pH = 0 to pH = 9.
An electrode and a battery were manufactured by changing to 0, and the experiment was performed under the same conditions as the measurement of the charge / discharge cycle life in Experiment 1 above.
As is clear from FIG. 2, when the treatment solution prepared by dissolving the reducing agent in the solution having the pH value of 0.5 to 6.0 was used, good charge / discharge cycle life was obtained. (Experiment 4) From the experimental results of the charge-discharge cycle characteristics of Experiment 1 above, the (X 3 ) battery was tested in spite of the fact that the surface-treated hydrogen storage alloy was used as the electrode material. The result was that the charge / discharge cycle life was shorter than that of the example battery.
【００３６】これは、水素吸蔵合金の不均一歪みの違い
からくるものではないかと考え、不均一歪みの大きさ
と、充放電サイクル寿命の関係を調べたので、その結果
を図３に示す。この実験の条件は、以下に示す通りであ
る。不均一歪みが異なる水素吸蔵合金を用いて、上記実
施例１と同様の表面処理、電極、電池の作製を行い、上
記実験１の充放電サイクル特性の測定と同様の条件で実
験を行った。It was thought that this might be due to the difference in the non-uniform strain of the hydrogen storage alloy, and the relationship between the magnitude of the non-uniform strain and the charge / discharge cycle life was investigated. The results are shown in FIG. The conditions of this experiment are as shown below. Using hydrogen storage alloys having different non-uniform strains, the same surface treatment, electrodes and batteries as in Example 1 were prepared, and experiments were conducted under the same conditions as the measurement of charge / discharge cycle characteristics in Experiment 1 above.
【００３７】尚、合金の不均一歪みは、合金作製時の冷
却速度と、アニール処理によって調整した。図３から明
らかなように、不均一歪みが３．５×１０-3以下の合金
について良好な値が得られた。
（その他の事項）
還元剤の種類について
水素化ホウ素ナトリウム以外に、水素化ホウ素カリウ
ム、水素化アルミニウムリチウム、次亜燐酸ナトリウ
ム、次亜燐酸カリウム、ホルマリン等を用いても同様の
効果が得られることを実験で確認している。
酸の種類及びｐＨについて
上記実施例では、酸として塩酸を使用したが、ほう酸、
リン酸、フッ酸等、他の酸を用いても、ｐＨが０．５〜
６．０の間で範囲で、同様の効果が得られることを実験
で確認した。
水素吸蔵合金の組成について
水素平衡圧が同程度であれば、本実施例に用いた合金と
同様に水素吸蔵を行うものと考えられるので、水素平衡
圧が同程度の合金であれば本実施例の組成に限ることは
ない。さらに、上記実施例では希土類金属系の水素吸蔵
合金を用いたが、チタン系の水素吸蔵合金にも同様の効
果が認められる。
上記実施例では、水素吸蔵合金鋳塊の粉砕時、或い
は、粉砕後の水素吸蔵合金に対して表面処理を行う場合
について記載したが、表面処理を行なわない水素吸蔵合
金を用いて電極を作製し、電極作製後の水素吸蔵合金に
対して処理を行なっても、同様の効果が得られることは
実験で確認されている。The non-uniform strain of the alloy was adjusted by the cooling rate during the alloy preparation and the annealing treatment. As is clear from FIG. 3, good values were obtained for alloys with a non-uniform strain of 3.5 × 10 −3 or less. (Other matters) Regarding the type of reducing agent, similar effects can be obtained by using potassium borohydride, lithium aluminum hydride, sodium hypophosphite, potassium hypophosphite, formalin, etc. in addition to sodium borohydride. Has been confirmed by experiments. Regarding the type and pH of acid In the above examples, hydrochloric acid was used as the acid, but boric acid,
Even if other acids such as phosphoric acid and hydrofluoric acid are used, the pH is 0.5 to
It was confirmed experimentally that the same effect was obtained in the range of 6.0. Regarding the composition of the hydrogen storage alloy, if the hydrogen equilibrium pressure is about the same, it is considered that hydrogen storage will be performed similarly to the alloy used in this example. The composition is not limited to. Further, although the rare earth metal-based hydrogen storage alloy is used in the above-mentioned examples, the same effect is recognized in the titanium-based hydrogen storage alloy. In the above examples, the case of crushing the hydrogen-absorbing alloy ingot, or the case of performing the surface treatment on the hydrogen-absorbing alloy after crushing, the electrode was produced using the hydrogen-absorbing alloy without surface treatment. It has been confirmed by experiments that the same effect can be obtained by treating the hydrogen storage alloy after the electrode is manufactured.
【００３８】[0038]
【発明の効果】以上説明したように、本発明によれば、
還元剤の添加された酸性水溶液を用いて、表面処理を行
なうことにより、水素吸蔵合金及び還元剤から水素が多
量に発生し、これに伴って水素吸蔵合金も多くの水素を
吸蔵するので水素吸蔵合金の活性度が向上し、充放電サ
イクル初期の高率放電特性、及び、低温放電特性が向上
した。また、電極材料として用いた水素吸蔵合金の不均
一歪みが３．５×１０-3以下であることから、充放電サ
イクルを繰り返し行っても、微粉化が進行することはな
く充放電サイクル寿命の長寿命化を図ることができた。As described above, according to the present invention,
A large amount of hydrogen is generated from the hydrogen storage alloy and the reducing agent by performing the surface treatment with an acidic aqueous solution containing a reducing agent, and the hydrogen storage alloy also stores a large amount of hydrogen accordingly. The activity of the alloy was improved, and the high rate discharge characteristics and the low temperature discharge characteristics at the beginning of the charge / discharge cycle were improved. Further, since the hydrogen storage alloy used as the electrode material has a non-uniform strain of 3.5 × 10 −3 or less, even if the charge / discharge cycle is repeated, pulverization does not proceed and the charge / discharge cycle life is shortened. We were able to extend the service life.
【図１】処理溶液のｐＨ値と高率放電特性との関係を示
す図である。FIG. 1 is a diagram showing a relationship between a pH value of a treatment solution and a high rate discharge characteristic.
【図２】処理溶液のｐＨ値と充放電サイクル寿命との関
係を示すグラフである。FIG. 2 is a graph showing the relationship between the pH value of the treatment solution and the charge / discharge cycle life.
【図３】不均一歪みと充放電サイクル寿命との関係を示
すグラフである。FIG. 3 is a graph showing the relationship between non-uniform strain and charge / discharge cycle life.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平１−132048（ＪＰ，Ａ) 特開 平４−121960（ＪＰ，Ａ) 特開 平３−152868（ＪＰ，Ａ) 特開 平５−135797（ＪＰ，Ａ) 特開 平５−114403（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) H01M 4/24 - 4/26 H01M 4/38 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-132048 (JP, A) JP-A-4-121960 (JP, A) JP-A-3-152868 (JP, A) JP-A-5- 135797 (JP, A) JP-A-5-114403 (JP, A) (58) Fields investigated (Int.Cl. 7 , DB name) H01M 4/24-4/26 H01M 4/38
Claims (4)
素化物電極の製造方法において、 不均一歪みが３．５×１０-3以下の水素吸蔵合金に対し
てｐＨ値が０．５〜６．０の酸性水溶液に還元剤を添加
した水溶液により表面処理を行うステップを有すること
を特徴とする金属水素化物蓄電池電極の製造方法。1. A method for producing a metal hydride electrode using a hydrogen storage alloy as a negative electrode material, wherein a pH value is 0.5 to 6 for a hydrogen storage alloy having a nonuniform strain of 3.5 × 10 −3 or less. A method for producing a metal hydride storage battery electrode, comprising a step of performing a surface treatment with an aqueous solution obtained by adding a reducing agent to an acidic aqueous solution of 0.0.
テップが水素吸蔵合金鋳塊の粉砕時に行われることを特
徴とする請求項１記載の金属水素化物電極の製造方法。2. The method for producing a metal hydride electrode according to claim 1, wherein the step of performing the surface treatment with the acidic aqueous solution is performed when the hydrogen storage alloy ingot is pulverized.
テップが電極を作製する前の水素吸蔵合金粉末に対して
行われることを特徴とする請求項１記載の金属水素化物
電極の製造方法。3. The method for producing a metal hydride electrode according to claim 1, wherein the step of performing the surface treatment with the acidic aqueous solution is performed on the hydrogen storage alloy powder before the electrode is produced.
に対して行われることを特徴とする請求項１記載の金属
水素化物電極の製造方法。4. The method for producing a metal hydride electrode according to claim 1, wherein the surface treatment with the acidic aqueous solution is performed on the electrode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29873193A JP3432870B2 (en) | 1993-11-29 | 1993-11-29 | Method for producing metal hydride electrode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29873193A JP3432870B2 (en) | 1993-11-29 | 1993-11-29 | Method for producing metal hydride electrode |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07153460A JPH07153460A (en) | 1995-06-16 |
| JP3432870B2 true JP3432870B2 (en) | 2003-08-04 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP29873193A Expired - Fee Related JP3432870B2 (en) | 1993-11-29 | 1993-11-29 | Method for producing metal hydride electrode |
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| Country | Link |
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| JP (1) | JP3432870B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100305176B1 (en) * | 1996-06-26 | 2001-11-30 | 다카노 야스아키 | Method for manufacturing hydrogen storage alloy electrode and hydrogen storage alloy electrode |
| TW445299B (en) * | 1996-10-16 | 2001-07-11 | Shinetsu Chemical Co | Method of producing hydrogen absorbing alloy powder, and electrode using hydrogen absorbing alloy powder produced by said method |
| JP3553752B2 (en) * | 1997-01-30 | 2004-08-11 | 三洋電機株式会社 | Method for producing hydrogen storage alloy electrode |
| CA2264134C (en) * | 1997-01-31 | 2004-12-07 | Sanyo Electric Co., Ltd. | Hydrogen absorbing alloy powder and process for producing same |
-
1993
- 1993-11-29 JP JP29873193A patent/JP3432870B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH07153460A (en) | 1995-06-16 |
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