JP3567941B2 - Nickel-hydrogen storage battery - Google Patents
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- JP3567941B2 JP3567941B2 JP24815694A JP24815694A JP3567941B2 JP 3567941 B2 JP3567941 B2 JP 3567941B2 JP 24815694 A JP24815694 A JP 24815694A JP 24815694 A JP24815694 A JP 24815694A JP 3567941 B2 JP3567941 B2 JP 3567941B2
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Description
【０００１】
【産業上の利用分野】
本発明はニッケル−水素蓄電池に関するもので、さらに詳しく言えば、そのセパレータを改良してガス吸収特性を良好にし、自己放電を抑制することを可能にしたニッケル−水素蓄電池に関するものである。
【０００２】
【従来の技術】
近年、ポータブル電子機器などに用いられる電池としては、有害物質を含まないということから、ニッケル−カドミウム蓄電池に代わってニッケル−水素蓄電池が多用されるようになってきている。
【０００３】
そして、このようなポータブル電子機器は、多機能化、小型化される傾向にあるため、使用される電池は高温度の環境下に高密度に実装されるようになってきている。
【０００４】
一方、従来のニッケル−水素蓄電池には、特開平３−１４５０５３号公報に記載されたようなポリアミド繊維からなるセパレータが用いられていた。
【０００５】
上記のようなニッケル−水素蓄電池は、高温度の環境下に実装すると、ポリアミド繊維が分解してその生成物によって自己放電が促進され、しかも負極に用いられている水素吸蔵合金から放出される水素が正極で消費されることによってさらに自己放電が加速することが知られている。
【０００６】
そのため、セパレータに耐熱性、耐酸化性にすぐれたポリオレフィン系合成樹脂からなる不織布を用い、特開平２−２７６１５４号公報に記載されたようにフッ素を含む反応ガスに接触させたり、特開平４−３６９５４号公報に記載されたようにスルホン基のような親水基を結合させたり、特開平４−２５５６６５号公報に記載されたようにコロナ放電処理を施したりして電解液との親和性を向上させることが提案されている。
【０００７】
また、セパレータにポリオレフィン系合成樹脂からなる不織布を用い、これにアクリル酸またはメタクリル酸等の親水性ビニルモノマーをグラフト重合して親水性をもたせることも提案されている。
【０００８】
さらに、セパレータに疎水性のポリオレフィン系合成樹脂と親水性のポリビニルアルコール系合成樹脂とを混紡した不織布を用いることも提案されている。
【０００９】
【発明が解決しようとする課題】
上記した従来のセパレータのうち、フッ素を含む反応ガスに接触させたり、スルホン基のような親水基を結合させたり、コロナ放電処理を施したりしたものは、繊維の間隙に保持された電解液によって水素の透過が抑制されて自己放電は抑制できるが、充電末期に正極で発生する酸素が負極で効果的に吸収されなくなって内圧が上昇しやすくなるという問題があった。
【００１０】
また、上記した従来のセパレータのうち、親水性ビニルモノマーをグラフト重合したものは、電解液が繊維の内部に保持されるため、繊維の間隙を酸素が良好に透過して負極で効果的に吸収されるが、自己放電を十分抑制することができないという問題があり、上記した従来のセパレータのうち、疎水性の合成樹脂と親水性の合成樹脂とを混紡した不織布は、電解液が親水性の合成樹脂側で保持されるため、疎水性の合成樹脂の表面を酸素が良好に透過して負極で効果的に吸収されるが、同様に自己放電を十分抑制することができないという問題があった。
【００１１】
【課題を解決するための手段】
上記課題を解決するため、本発明は、水素吸蔵合金からなる負極とニッケル正極との間にセパレータを介在してなるニッケル−水素蓄電池において、前記セパレータは、繊維径が３μｍ以下のポリオレフィン系合成樹脂からなる第１繊維層と繊維径が１５μｍ以上のポリオレフィン系合成樹脂からなる第２繊維層とを一体化した不織布に、アクリル酸またはメタクリル酸から選択された親水性ビニルモノマーの少なくとも一方をグラフト重合したものであり、前記第１繊維層を正極側に当接し、前記第２繊維層を負極側に当接するように配したことを特徴とするものである。
【００１２】
また、本発明は、上記したニッケル−水素蓄電池において、セパレータの、第１繊維層はポリプロピレン繊維からなり、第２繊維層はポリエチレン繊維または表面をポリエチレンで被覆したポリプロピレン繊維からなり、第２繊維層のグラフト率が第１繊維層のグラフト率より高くなるようにしたことを特徴とするものである。
【００１３】
さらに、本発明は、上記した各ニッケル−水素蓄電池において、セパレータの、第２繊維層の厚みを第１繊維層の厚みより大きくしたことを特徴とするものである。
【００１４】
【作用】
本発明によれば、正極側に繊維径が３μｍ以下のポリオレフィン系合成樹脂からなる第１繊維層を当接させ、負極側に繊維径が１５μｍ以上のポリオレフィン系合成樹脂からなる第２繊維層を当接させているので、正極側は密に充填された繊維同士の間隙に電解液を満たして負極の水素吸蔵合金から放出された水素を正極に到達し難くし、それによって自己放電を抑制することができ、また負極側は繊維の内部に電解液を保持して繊維の間隙を酸素が透過しやすくし、それによって充電末期に正極で発生する酸素を負極で効果的に吸収させることができる。
【００１５】
また、本発明によれば、第１繊維層にポリプロピレン繊維を、第２繊維層にポリエチレン繊維または表面をポリエチレンで被覆したポリプロピレン繊維を用いているので、グラフト重合に対する反応性が低いポリプロピレン繊維からなる第１繊維層のグラフト率を第２繊維層のグラフト率より低くすることができ、それによって第１繊維層は繊維の内部より繊維同士の間隙に多くの電解液を満たして自己放電を抑制することができる。
【００１６】
さらに、本発明によれば、第２繊維層の厚みを第１繊維層の厚みより大きくしているので、第２繊維層に多くの繊維の間隙を形成することができ、それによって繊維の間隙を酸素が透過しやすくなって充電末期に正極で発生する酸素を負極で効果的に吸収させることができる。
【００１７】
【実施例】
以下、本発明を実施例に基づいて説明する。
【００１８】
本発明電池に用いるセパレータａは、第１繊維層としての繊維径２μｍ、重量２０ｇ／ｍ２ 、厚さ０．０８ｍｍのポリプロピレン繊維からなる不織布と、第２繊維層としての繊維径２０μｍ、重量３０ｇ／ｍ２ 、厚さ０．０８ｍｍのポリエチレンで被覆したポリプロピレン繊維からなる不織布とを熱プレス加工して一体化した後、前記不織布に電子線加速装置によって加速電圧を３００ｋＶ、ビーム電流を１０ｍＡとして電子線を１００ｋＧｙ照射した後、あらかじめ窒素によって脱酸素されたアクリル酸２０重量部、水８０重量部、モール氏塩１重量部からなる反応液に１時間浸漬してグラフト重合したもので、グラフト重合した後第１繊維層と第２繊維層とを分離してグラフト率を調査したところ、第１繊維層は１８％、第２繊維層は４２％であった。
【００１９】
一方、比較用電池に用いるセパレータｂとして、繊維径２０μｍ、重量５０ｇ／ｍ２ 、厚さ０．１５ｍｍのポリエチレンで被覆したポリプロピレン繊維からなる不織布に同じ方法でグラフト重合し、グラフト率４４％のものを作製した。
【００２０】
また、比較用電池に用いるセパレータｃとして、繊維径２μｍ、重量４５ｇ／ｍ２ 、厚さ０．１８ｍｍのポリプロピレン繊維からなる不織布に同じ方法でグラフト重合し、グラフト率２０％のものを作製した。
【００２１】
さらに、従来電池に用いるセパレータｄとして、繊維径２０μｍ、重量７０ｇ／ｍ２ 、厚さ０．１６ｍｍのポリプロピレン繊維からなる不織布にスルホン基を結合したものを作製した。
【００２２】
また、従来電池に用いるセパレータｅとして、繊維径２５μｍ、重量７０ｇ／ｍ２ 、厚さ０．１７ｍｍの６−６ナイロン不織布からなるものを作製した。
【００２３】
こうして得られた各セパレータａ，ｂ，ｃ，ｄ，ｅを用い、水酸化ニッケル粉末を主体とするペースト式ニッケル極を正極、水素吸蔵合金粉末からなる水素極を負極、水酸化カリウム水溶液を電解液とした、公称容量が１１００ｍＡＨの密閉形ニッケル−水素電池Ａ，Ｂ，Ｃ，Ｄ，Ｅを作製した。
【００２４】
なお、上記したセパレータの第１繊維層に用いる繊維径は、繊維の間隙を電解液で満たして正極の表面を電解液で覆うだけの緻密さを確保するために３μｍ以下にすることが好ましく、第２繊維層に用いる繊維径はガスの透過に必要な間隙を確保するために１５μｍ以上にすることが好ましい。
【００２５】
これらの各電池を４５℃の温度下で保存した時の自己放電特性を調査したところ、図１のような結果が得られた。
【００２６】
図１から、本発明電池Ａは正極の表面を電解液で覆うことができるため、正極側への水素の移動が抑制されて比較電池Ｃおよび従来電池Ｄとほぼ同程度の自己放電特性を示したのに対し、比較電池Ｂおよび従来電池Ｅは正極の表面に繊維同士の間隙が形成されるため、自己放電が大きくなることがわかった。
【００２７】
次に、これらの各電池を５℃の温度下、充電電流１Ｃの充電を行って電池の内圧を調査したところ、表１のような結果が得られた。
【００２８】
【表１】
表１から、本発明電池Ａおよび比較電池Ｂは負極側に当接するセパレータの表面をガスが容易に移動するため、ガス吸収性能が良好になって内圧が低くなったのに対し、比較電池Ｃおよび従来電池Ｄは繊維同士の間隙に満たされる電解液によってガスの移動が阻害されて内圧が高くなることがわかった。
【００３０】
次に、他の本発明電池に用いるセパレータｆとして、繊維径２μｍ、重量１０ｇ／ｍ２ 、厚さ０．０４ｍｍのポリプロピレン繊維からなる第１繊維層としての不織布と、繊維径２０μｍ、重量４０ｇ／ｍ２ 、厚さ０．１１ｍｍのポリエチレンで被覆したポリプロピレン繊維からなる第２繊維層としての不織布とを熱プレス加工して一体化した後、前記不織布に電子線加速装置によって加速電圧を３００ｋＶ、ビーム電流を１０ｍＡとして電子線を１００ｋＧｙ照射した後、あらかじめ窒素によって脱酸素されたアクリル酸２０重量部、水８０重量部、モール氏塩１重量部からなる反応液に１時間浸漬してグラフト重合し、その第１繊維層のグラフト率が１８％、第２繊維層のグラフト率が３８％のものを作製した。
【００３１】
また、他の本発明電池に用いるセパレータｇとして、繊維径２μｍ、重量２５ｇ／ｍ２ 、厚さ０．１０ｍｍのポリプロピレン繊維からなる第１繊維層としての不織布と、繊維径２０μｍ、重量２５ｇ／ｍ２ 、厚さ０．０７ｍｍのポリエチレンで被覆したポリプロピレン繊維からなる第２繊維層としての不織布とを熱プレス加工して一体化した後、前記した方法でグラフト重合し、その第１繊維層のグラフト率が１７％、第２繊維層のグラフト率が４０％のものを作製した。
【００３２】
こうして得られた各セパレータｆ，ｇを用い、水酸化ニッケル粉末を主体とするペースト式ニッケル極を正極、水素吸蔵合金粉末からなる水素極を負極、水酸化カリウム水溶液を電解液とした、公称容量が１１００ｍＡＨの密閉形ニッケル−水素電池Ｆ，Ｇを作製した。
【００３３】
次に、これらの各電池を５℃の温度下、充電電流１Ｃの充電を行って電池の内圧を調査したところ、表２のような結果が得られた。
【００３４】
【表２】
表２から、第２繊維層の厚さを第１繊維層の厚さより大きくした本発明電池Ｆは第２繊維層の厚さを第１繊維層の厚さより小さくした本発明電池Ｇより内圧が低くなり、このことから第２繊維層の厚さを第１繊維層の厚さより大きくした方がガス吸収性能が良好になることがわかる。
【００３６】
なお、上記した実施例では、第１繊維層にポリプロピレン繊維からなる不織布を、第２繊維層にポリエチレンで被覆したポリプロピレン繊維からなる不織布を用いたが、第１繊維層にポリプロピレン繊維からなる不織布を、第２繊維層にポリエチレン繊維からなる不織布を用いてもよい。
【００３７】
また、上記した繊維以外に、ポリエチレン繊維とポリエチレンとポリプロピレンの共重合繊維のような他のポリオレフィン系合成樹脂からなる繊維を組み合わせてもよいが、正極側に当接する第１繊維層のグラフト率が負極側に当接する第２繊維層のグラフト率より高くならないようにすることが必要である。
【００３８】
さらに、上記した実施例では、親水性ビニルモノマーとして、アクリル酸を用いたが、メタクリル酸のような他の親水性ビニルモノマーを用いてもよいことは言うまでもない。
【００３９】
そして、グラフト重合は、モノマーと織布または不織布の共存下で放射線を照射する同時照射法と、あらかじめ放射線を照射してラジカルを生成させた織布または不織布にモノマーを接触させる前照射法とがあるが、いずれの方法であってもよいことは言うまでもない。
【００４０】
【発明の効果】
上記した如く、本発明のニッケル−水素電池は、負極から放出された水素が正極に到達するのを抑制することができ、正極で発生した酸素を効率よく負極に導くことができるので、その高温下での自己放電特性、ガス吸収特性を改良することができる。
【図面の簡単な説明】
【図１】本発明電池Ａ、比較電池Ｂ，Ｃおよび従来電池Ｄ，Ｅの自己放電特性を比較した図である。[0001]
[Industrial applications]
The present invention relates to a nickel-hydrogen storage battery, and more particularly, to a nickel-hydrogen storage battery in which a separator is improved to improve gas absorption characteristics and suppress self-discharge.
[0002]
[Prior art]
In recent years, nickel-hydrogen storage batteries have been increasingly used in place of nickel-cadmium storage batteries because they do not contain harmful substances as batteries used in portable electronic devices and the like.
[0003]
Since such portable electronic devices tend to be multifunctional and miniaturized, batteries to be used have been increasingly mounted in high-temperature environments.
[0004]
On the other hand, in a conventional nickel-hydrogen storage battery, a separator made of polyamide fiber as described in JP-A-3-14553 has been used.
[0005]
When a nickel-hydrogen storage battery as described above is mounted in a high-temperature environment, the polyamide fibers are decomposed and self-discharge is promoted by the product, and hydrogen released from the hydrogen storage alloy used for the negative electrode is used. It is known that the self-discharge is further accelerated by the consumption of methane at the positive electrode.
[0006]
Therefore, a non-woven fabric made of a polyolefin-based synthetic resin having excellent heat resistance and oxidation resistance is used for the separator, and the separator is contacted with a reaction gas containing fluorine as described in JP-A-2-276154. Improving the affinity with the electrolytic solution by bonding a hydrophilic group such as a sulfone group as described in JP-A-36954, or performing a corona discharge treatment as described in JP-A-4-255665. It has been proposed to do so.
[0007]
It has also been proposed to use a non-woven fabric made of a polyolefin-based synthetic resin for the separator, and to graft-polymerize a hydrophilic vinyl monomer such as acrylic acid or methacrylic acid to the separator to impart hydrophilicity.
[0008]
Further, it has been proposed to use a nonwoven fabric obtained by blending a hydrophobic polyolefin-based synthetic resin and a hydrophilic polyvinyl alcohol-based synthetic resin for the separator.
[0009]
[Problems to be solved by the invention]
Of the above-mentioned conventional separators, those that have been brought into contact with a fluorine-containing reaction gas, or that have bonded a hydrophilic group such as a sulfone group, or that have been subjected to corona discharge treatment, are treated by an electrolytic solution held in a gap between fibers. Although the permeation of hydrogen is suppressed and self-discharge can be suppressed, there is a problem that oxygen generated at the positive electrode at the end of charging is not effectively absorbed by the negative electrode, and the internal pressure tends to increase.
[0010]
Among the above-mentioned conventional separators, those obtained by graft-polymerizing a hydrophilic vinyl monomer, since the electrolytic solution is retained inside the fibers, oxygen is well transmitted through the gaps between the fibers and effectively absorbed by the negative electrode. However, there is a problem that self-discharge cannot be sufficiently suppressed, and among the conventional separators described above, the nonwoven fabric obtained by blending a hydrophobic synthetic resin and a hydrophilic synthetic resin has Since it is held on the synthetic resin side, oxygen is well transmitted through the surface of the hydrophobic synthetic resin and is effectively absorbed by the negative electrode, but similarly, there is a problem that self-discharge cannot be sufficiently suppressed. .
[0011]
[Means for Solving the Problems]
In order to solve the above problems, the present invention relates to a nickel-hydrogen storage battery in which a separator is interposed between a negative electrode made of a hydrogen storage alloy and a nickel positive electrode, wherein the separator has a fiber diameter of 3 μm or less. Graft polymerization of at least one of a hydrophilic vinyl monomer selected from acrylic acid and methacrylic acid onto a nonwoven fabric obtained by integrating a first fiber layer made of acrylic resin and a second fiber layer made of a polyolefin-based synthetic resin having a fiber diameter of 15 μm or more. Wherein the first fiber layer is arranged to contact the positive electrode side, and the second fiber layer is arranged to contact the negative electrode side.
[0012]
The present invention also provides the nickel-hydrogen storage battery described above, wherein the first fiber layer of the separator is made of polypropylene fiber, the second fiber layer is made of polyethylene fiber or polypropylene fiber whose surface is coated with polyethylene, In which the graft ratio is higher than the graft ratio of the first fiber layer.
[0013]
Further, the present invention is characterized in that in each of the above-described nickel-hydrogen storage batteries, the thickness of the second fiber layer of the separator is larger than the thickness of the first fiber layer.
[0014]
[Action]
According to the present invention, a first fiber layer made of a polyolefin-based synthetic resin having a fiber diameter of 3 μm or less is brought into contact with the positive electrode side, and a second fiber layer made of a polyolefin-based synthetic resin having a fiber diameter of 15 μm or more is brought into contact with the negative electrode side. Because it is in contact, the positive electrode side fills the gap between the densely packed fibers with electrolyte so that hydrogen released from the hydrogen storage alloy of the negative electrode hardly reaches the positive electrode, thereby suppressing self-discharge In addition, the negative electrode side can hold the electrolyte inside the fiber to facilitate the permeation of oxygen through the interstices of the fiber, so that the oxygen generated at the positive electrode at the end of charging can be effectively absorbed by the negative electrode. .
[0015]
According to the present invention, since the first fiber layer is made of polypropylene fiber and the second fiber layer is made of polyethylene fiber or polypropylene fiber whose surface is coated with polyethylene, it is made of polypropylene fiber having low reactivity to graft polymerization. The graft ratio of the first fiber layer can be lower than the graft ratio of the second fiber layer, so that the first fiber layer fills the gap between the fibers with more electrolyte than the inside of the fiber to suppress self-discharge. be able to.
[0016]
Further, according to the present invention, since the thickness of the second fiber layer is made larger than the thickness of the first fiber layer, it is possible to form a large number of fiber gaps in the second fiber layer. And oxygen generated at the positive electrode at the end of charging can be effectively absorbed by the negative electrode.
[0017]
【Example】
Hereinafter, the present invention will be described based on examples.
[0018]
The separator a used in the battery of the present invention includes a nonwoven fabric made of polypropylene fibers having a fiber diameter of 2 μm and a weight of 20 g / m 2 and a thickness of 0.08 mm as a first fiber layer, and a fiber diameter of 20 μm and a weight of 30 g as a second fiber layer. / M 2 , and a non-woven fabric made of polypropylene fiber coated with polyethylene having a thickness of 0.08 mm and integrated by hot pressing, and then the electron beam is accelerated to the non-woven fabric by an electron beam accelerator at 300 kV and a beam current of 10 mA. After irradiating the wire with 100 kGy, it was immersed for 1 hour in a reaction solution composed of 20 parts by weight of acrylic acid, 80 parts by weight of water, and 1 part by weight of Mohr's salt, which had been deoxygenated with nitrogen, and subjected to graft polymerization. Then, when the first fiber layer and the second fiber layer were separated and the graft ratio was examined, the first fiber layer was 18%, and the second fiber layer was 18%. It was 2%.
[0019]
On the other hand, the separator b used in the comparative battery was graft-polymerized to a non-woven fabric made of polypropylene fiber coated with polyethylene having a fiber diameter of 20 μm, a weight of 50 g / m 2 and a thickness of 0.15 mm by the same method, and a graft ratio of 44%. Was prepared.
[0020]
In addition, as a separator c used for a comparative battery, a nonwoven fabric made of polypropylene fiber having a fiber diameter of 2 μm, a weight of 45 g / m 2 , and a thickness of 0.18 mm was graft-polymerized by the same method to produce a separator c having a graft ratio of 20%.
[0021]
Further, as a separator d used in a conventional battery, a separator formed by bonding a sulfone group to a nonwoven fabric made of polypropylene fiber having a fiber diameter of 20 μm, a weight of 70 g / m 2 , and a thickness of 0.16 mm was prepared.
[0022]
As a separator e used in a conventional battery, a separator made of a 6-6 nylon nonwoven fabric having a fiber diameter of 25 μm, a weight of 70 g / m 2 , and a thickness of 0.17 mm was prepared.
[0023]
Using the thus obtained separators a, b, c, d, and e, a paste-type nickel electrode mainly composed of nickel hydroxide powder was used as a positive electrode, a hydrogen electrode made of a hydrogen storage alloy powder was used as a negative electrode, and an aqueous potassium hydroxide solution was electrolyzed. The sealed nickel-metal hydride batteries A, B, C, D and E having a nominal capacity of 1100 mAH were prepared.
[0024]
In addition, the fiber diameter used for the first fiber layer of the separator is preferably 3 μm or less in order to ensure that the gap between the fibers is filled with the electrolyte and the surface of the positive electrode is covered with the electrolyte. The fiber diameter used for the second fiber layer is preferably 15 μm or more in order to secure a gap required for gas permeation.
[0025]
When the self-discharge characteristics of each of these batteries when stored at a temperature of 45 ° C. were examined, the results as shown in FIG. 1 were obtained.
[0026]
From FIG. 1, it can be seen from FIG. 1 that the battery A of the present invention can cover the surface of the positive electrode with the electrolytic solution, so that the movement of hydrogen to the positive electrode side is suppressed, and the self-discharge characteristics of the comparative battery C and the conventional battery D are almost the same. On the other hand, in the comparative battery B and the conventional battery E, the self-discharge was found to be large because the gap between the fibers was formed on the surface of the positive electrode.
[0027]
Next, each of these batteries was charged at a charging current of 1 C at a temperature of 5 ° C., and the internal pressure of the batteries was examined. The results shown in Table 1 were obtained.
[0028]
[Table 1]
From Table 1, it can be seen that the battery A of the present invention and the comparative battery B exhibited good gas absorption performance and a low internal pressure because the gas easily moved on the surface of the separator in contact with the negative electrode, whereas the comparative battery C In addition, it was found that in the conventional battery D, the movement of gas was inhibited by the electrolytic solution filled in the gap between the fibers, and the internal pressure was increased.
[0030]
Next, a non-woven fabric as a first fiber layer made of a polypropylene fiber having a fiber diameter of 2 μm, a weight of 10 g / m 2 and a thickness of 0.04 mm as a separator f used in another battery of the present invention, a fiber diameter of 20 μm, and a weight of 40 g / m 2 m 2 , a non-woven fabric as a second fiber layer made of a polypropylene fiber coated with polyethylene having a thickness of 0.11 mm was integrated with a non-woven fabric by hot pressing, and then an acceleration voltage of 300 kV was applied to the non-woven fabric using an electron beam accelerator. After irradiating 100 kGy with an electron beam at a current of 10 mA, the polymer was immersed in a reaction solution consisting of 20 parts by weight of acrylic acid, 80 parts by weight of water, and 1 part by weight of Mohr's salt, which had been previously deoxygenated with nitrogen, for 1 hour to perform graft polymerization. The first fiber layer had a graft ratio of 18% and the second fiber layer had a graft ratio of 38%.
[0031]
As another separator g used in the battery of the present invention, a non-woven fabric as a first fiber layer made of a polypropylene fiber having a fiber diameter of 2 μm, a weight of 25 g / m 2 and a thickness of 0.10 mm, a fiber diameter of 20 μm, and a weight of 25 g / m 2 2. A non-woven fabric as a second fiber layer made of polypropylene fiber coated with polyethylene having a thickness of 0.07 mm is integrated with a non-woven fabric by hot pressing, and then graft-polymerized by the method described above, and the first fiber layer is grafted. The one having a ratio of 17% and a graft ratio of the second fiber layer of 40% was produced.
[0032]
Using each of the separators f and g thus obtained, the nominal capacity was such that a paste-type nickel electrode mainly composed of nickel hydroxide powder was used as a positive electrode, a hydrogen electrode composed of a hydrogen storage alloy powder was used as a negative electrode, and an aqueous potassium hydroxide solution was used as an electrolyte. Manufactured sealed nickel-metal hydride batteries F and G having 1100 mAH.
[0033]
Next, each of these batteries was charged at a charging current of 1 C at a temperature of 5 ° C., and the internal pressure of the batteries was examined. The results shown in Table 2 were obtained.
[0034]
[Table 2]
From Table 2, it can be seen that the battery F of the present invention in which the thickness of the second fiber layer was larger than the thickness of the first fiber layer had an internal pressure higher than that of the battery G of the present invention in which the thickness of the second fiber layer was smaller than the thickness of the first fiber layer. This indicates that the gas absorption performance is better when the thickness of the second fiber layer is larger than the thickness of the first fiber layer.
[0036]
In the above-described embodiment, the nonwoven fabric made of polypropylene fiber is used for the first fiber layer, and the nonwoven fabric made of polypropylene fiber coated with polyethylene is used for the second fiber layer. However, the nonwoven fabric made of polypropylene fiber is used for the first fiber layer. Alternatively, a nonwoven fabric made of polyethylene fiber may be used for the second fiber layer.
[0037]
Further, in addition to the above-described fibers, a fiber made of another polyolefin-based synthetic resin such as a polyethylene fiber and a copolymer fiber of polyethylene and polypropylene may be combined, but the graft ratio of the first fiber layer in contact with the positive electrode side may be reduced. It is necessary that the graft ratio is not higher than the graft ratio of the second fiber layer in contact with the negative electrode side.
[0038]
Further, in the above-described embodiment, acrylic acid is used as the hydrophilic vinyl monomer, but it is needless to say that another hydrophilic vinyl monomer such as methacrylic acid may be used.
[0039]
Graft polymerization includes a simultaneous irradiation method of irradiating radiation in the coexistence of a monomer and a woven or nonwoven fabric, and a pre-irradiation method of contacting the monomer with a woven or nonwoven fabric that has been previously irradiated with radiation to generate radicals. However, it goes without saying that either method may be used.
[0040]
【The invention's effect】
As described above, the nickel-hydrogen battery of the present invention can suppress the hydrogen released from the negative electrode from reaching the positive electrode, and can efficiently guide oxygen generated at the positive electrode to the negative electrode. The self-discharge characteristics and gas absorption characteristics can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram comparing self-discharge characteristics of a battery A of the present invention, comparative batteries B and C, and conventional batteries D and E.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24815694A JP3567941B2 (en) | 1994-10-13 | 1994-10-13 | Nickel-hydrogen storage battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24815694A JP3567941B2 (en) | 1994-10-13 | 1994-10-13 | Nickel-hydrogen storage battery |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08115739A JPH08115739A (en) | 1996-05-07 |
| JP3567941B2 true JP3567941B2 (en) | 2004-09-22 |
Family
ID=17174061
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24815694A Expired - Lifetime JP3567941B2 (en) | 1994-10-13 | 1994-10-13 | Nickel-hydrogen storage battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3567941B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2978785B2 (en) * | 1996-09-12 | 1999-11-15 | ニッポン高度紙工業株式会社 | Separator paper for alkaline batteries |
| JP3332139B2 (en) * | 1996-09-26 | 2002-10-07 | 松下電器産業株式会社 | Sealed alkaline storage battery |
-
1994
- 1994-10-13 JP JP24815694A patent/JP3567941B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08115739A (en) | 1996-05-07 |
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