JP3587967B2

JP3587967B2 - Alkaline batteries

Info

Publication number: JP3587967B2
Application number: JP26135397A
Authority: JP
Inventors: 誠一日方
Original assignee: Toshiba Battery Co Ltd
Current assignee: FDK Twicell Co Ltd
Priority date: 1997-09-26
Filing date: 1997-09-26
Publication date: 2004-11-10
Anticipated expiration: 2017-09-26
Also published as: JPH11102671A

Description

【０００１】
【発明の属する技術分野】
本発明は、アルカリ乾電池の性能改善に関するものである。
【０００２】
【従来の技術】
ノート型パソコン，ＣＤプレーヤ，ＭＤプレーヤ，液晶テレビ等の携帯用ＡＶ機器，また、携帯電話などの超重負荷，重負荷の用途が最近のアルカリ乾電池に要求されてきている。
【０００３】
かかるアルカリ乾電池において、その正極缶は、鋼板の両面に予めニッケルメッキを施したものをプレス絞りしごき加工するか、鋼板のみで絞り加工した後ニッケルメッキを施し、それぞれ内面に黒鉛粉末を主成分とする導電性被膜を形成させたものが使用されており、これにより正極合剤と正極缶との接触抵抗を低減させ、重負荷特性を改善している。
【０００４】
【発明が解決しようとする課題】
ところでアルカリ乾電池において高容量化を実現させるためには、正極合剤中の二酸化マンガン含有率を増加させなければならず、必然的に導電剤の黒鉛粉末の含有率が低くなる。このことは、正極合剤と正極缶との接触抵抗を増大させ、短絡電流の低下や重負荷特性を低下させる原因となる。
【０００５】
この対策として、上記したように正極缶の内面に導電性被膜を形成させることが行われているが、このような高容量化電池は、貯蔵後、特に高温貯蔵後に重負荷特性が低下するという問題がある。
本発明は上記問題に対処してなされたもので、アルカリ乾電池の高容量化を達成し、かつ貯蔵後の重負荷特性の低下を防止することを目的とする。
【０００６】
【課題を解決するための手段】
本発明は上記問題を正極缶を改良することによって達成した。すなわち本発明は、正極端子を兼ねる有底円筒の正極缶と、その正極缶内に配置された中空円筒状の正極合剤と、有底円筒状のセパレータを介して前記正極合剤の中空部に充填されたゲル状亜鉛負極とを備えるアルカリ乾電池において、前記正極缶として、予め両面にニッケルメッキ層を形成させた冷間圧延鋼板材の一方の面にニッケル−銀合金メッキ層、またはニッケル−クロム合金メッキ層を形成し、その面が内面になるようにプレス絞りしごき加工した缶を使用したことを特徴とする。
【０００７】
本発明のアルカリ乾電池で使用する正極缶は、その内面に形成されたニッケル−銀合金メッキ層またはニッケル−クロム合金メッキ層が、プレス絞りしごき加工時に発生した非常に細かいひび割れによって凹凸面を構成するので、正極合剤や導電性被膜との接触面積が大きくなり、電池の内部抵抗を低減させる。一方、ニッケル−銀合金メッキ層、またはニッケル−クロム合金メッキ層の下には更にニッケルメッキ層が形成されているので、これらの層がひび割れしても鉄の下地が露出することが少ない。したがって、高温貯蔵した際の鉄の酸化により、正極合剤や導電性被膜との接触抵抗が大きくなることがなく、高温貯蔵後の重負荷特性の劣化が小さい。
【０００８】
本発明のアルカリ乾電池はこのような特性を有するので、正極合剤中の二酸化マンガンの量を増加させ、その結果、黒鉛粉末含有量を８ｗｔ％以下にしても、従来のような問題がなく、高容量化を達成できる。
【０００９】
【発明の実施の形態】
以下、本発明の実施例について詳細に説明する。
（実施例１）
まず、予め両面に厚さ１〜２μｍのニッケルメッキ層が形成された冷間圧延鋼板材の一方の面に、更に厚さ１〜２μｍのニッケル−銀合金メッキ層を形成させた。この鋼板を用いて、ニッケル−銀合金メッキ層面が内側になるように、有底の円筒形にプレス絞りしごき加工して正極缶を形成した。この正極缶のメッキ層の構成を図２に示す。この図に示されるように、正極缶の鋼板９には厚さ１〜２μｍのニッケルメッキ層１０が形成され、その上に、缶内側になる面に厚さ１〜２μｍのニッケル−銀合金メッキ層１１が形成されている。
【００１０】
このように形成した正極缶の内面に、開口部のガスケットと接する部分を除いて黒鉛粉末を主成分とする導電性被膜を形成した。導電性被膜の塗布方法は、黒鉛粉末を主成分とする導電性塗料をメチルエチルケトン等の低沸点有機溶剤にて希釈し、スプレーガンによって霧状に正極缶内面に塗布することによって行い、正極缶開口部のガスケットに接する部分には塗布しないようにする。導電塗料をスプレーガンにて塗布した後、乾燥機にて溶剤を蒸発させる。残った導電膜の厚さは１〜１０μｍ程度が望ましい。この正極缶のメッキ層の構成を図３に示す。図３において１２は導電性被膜である。
【００１１】
図３に示す導電性被膜が形成された正極缶を用いて、図１に示すＪＩＳ規格ＬＲ６形（単３形）アルカリ乾電池を組み立てた。この図１において、１は前記の方法で製造した正極端子を兼ねる有底円筒形の正極缶であり、この正極缶内には円筒状に加圧成形した３個の正極合剤２が分割充填されている。正極合剤２は二酸化マンガン粉末と黒鉛粉末を混合し、これを成形型を用いて所定の圧力で中空円筒状に加圧成形したものであり、放電容量の高容量化のために正極合剤２中の黒鉛粉末含有率は８ｗｔ％となっている。
【００１２】
また、正極合剤２の中空部にはアセタール化ポリビニルアルコール繊維の不織布からなる有底円筒状のセパレータ３が配置されている。このセパレータ３を介して、無汞化亜鉛合金粉末、アルカリ電解液及びゲル化剤としてのポリアクリル酸からなるゲル状亜鉛負極４が充填されている。ゲル状亜鉛負極４内には真鍮製の負極集電棒５が、その先端部をゲル状負極４に差し込むようにして装着されている。負極集電棒５の上部外周及び正極缶１の上部内周面には二重環状のポリアミド樹脂からなる絶縁ガスケット６が配設されている。また、絶縁ガスケット６の二重環状部の間にはリング状の金属板７が配設され、かつ金属板７には負極端子を兼ねる帽子型の金属封口板８が集電棒５の頭部に当接するように配設されている。そして、正極缶１の開口縁を内方に屈曲させることによりガスケット６及び金属封口板８で正極缶１内を密封口している。
【００１３】
（実施例２）
実施例１のニッケル−銀合金メッキ層の代わりに１〜２μｍのニッケル−クロム合金メッキ層を形成した以外は実施例１と全く同様にしてＪＩＳ規格ＬＲ６形（単３形）アルカリ乾電池を組み立てた。
【００１４】
（実施例３）
黒鉛粉末を主成分とする導電性被膜を形成しないこと以外は実施例１と同様にしてＪＩＳ規格ＬＲ６形（単３形）アルカリ乾電池を組み立てた。
【００１５】
（実施例４）
黒鉛粉末を主成分とする導電性被膜を形成しないこと以外は実施例２と同様にしてＪＩＳ規格ＬＲ６形（単３形）アルカリ乾電池を組み立てた。
【００１６】
（比較例１）
予め両面に厚さ１〜２μｍのニッケルメッキ層を形成させた冷間圧延鋼板材を有底の円筒形にプレス絞りしごき加工し、内側面に黒鉛粉末を主成分とする導電性被膜を形成したものを正極缶として用い、それ以外は実施例１と同様にしてＪＩＳ規格ＬＲ６形（単３形）アルカリ乾電池を組み立てた。
【００１７】
（比較例２）
冷間圧延鋼板材を有底の円筒形にプレス絞りしごき加工した後で、厚さ１〜２μｍのニッケルメッキ層を形成させ、内側面に黒鉛粉末を主成分とする導電性被膜を形成したものを正極缶として用い、それ以外は実施例１と同様にしてＪＩＳ規格ＬＲ６形（単３形）アルカリ乾電池を組み立てた。
【００１８】
（比較例３）
内側面に黒鉛粉末を主成分とする導電性被膜を形成しないで、それ以外は比較例１と同様にしてＪＩＳ規格ＬＲ６形（単３形）アルカリ乾電池を組み立てた。
【００１９】
（比較例４）
内側面に黒鉛粉末を主成分とする導電性被膜を形成しないで、それ以外は比較例２と同様にしてＪＩＳ規格ＬＲ６形（単３形）アルカリ乾電池を組み立てた。
【００２０】
上記のようにして組み立てた実施例１〜４、比較例１〜４の各ＬＲ６形アルカリ乾電池について、６０℃で０日、１０日及び６０日間貯蔵した後の、２０℃における内部抵抗と放電容量を調べ、その結果を表１に示した。内部抵抗（ｍΩ）はそれぞれの電池１０個を１ｋＨｚの交流抵抗計を用い測定し、それらの平均値を示した。放電容量はそれぞれの電池１０個について２Ω連続放電試験を実施し、終止電圧０．９Ｖまでの持続時間（ｍｉｎ）の平均値を示した。
【００２１】
【表１】

【００２２】
上記表から明らかなように、実施例１〜４は、比較例１〜４に比べて、６０℃に６０日間貯蔵しても電池の内部抵抗の増大が少なく、放電容量の劣化も少ないことが判る。
【００２３】
【発明の効果】
以上説明したように、本発明のアルカリ乾電池は、高容量で重負荷特性に優れており、また貯蔵特性にも優れている。
【図面の簡単な説明】
【図１】本発明の一実施例であるアルカリ乾電池の断面図。
【図２】本発明の実施例における正極缶の層構成図。
【図３】本発明の他の実施例における正極缶の層構成図。
【符号の説明】
１…正極缶、２…正極合剤、３…セパレータ、４…ゲル状亜鉛負極、５…負極集電棒、６…絶縁ガスケット、７…リング状金属板、８…金属封口板、９…鋼板、１０…ニッケルメッキ層、１１…ニッケル−銀合金メッキ層、１２…黒鉛粉末を主成分とする導電性被膜層。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to improving the performance of alkaline dry batteries.
[0002]
[Prior art]
Recently, alkaline dry batteries have been demanded for use in portable AV devices such as notebook personal computers, CD players, MD players, and liquid crystal televisions, and for use with ultra-heavy loads and heavy loads such as mobile phones.
[0003]
In such an alkaline dry battery, the positive electrode can is press-drawn and ironed on both surfaces of a steel plate in advance with nickel plating, or is subjected to nickel plating after drawing only with the steel plate, and the inner surface of each is mainly made of graphite powder. A conductive film having a conductive film formed thereon is used, whereby the contact resistance between the positive electrode mixture and the positive electrode can is reduced, and the heavy load characteristics are improved.
[0004]
[Problems to be solved by the invention]
By the way, in order to realize a high capacity in an alkaline dry battery, the content of manganese dioxide in the positive electrode mixture must be increased, and the content of graphite powder as a conductive agent is inevitably reduced. This increases the contact resistance between the positive electrode mixture and the positive electrode can, causing a reduction in short-circuit current and a reduction in heavy load characteristics.
[0005]
As a countermeasure, a conductive film is formed on the inner surface of the positive electrode can as described above. However, such a high capacity battery has a problem that the heavy load characteristics are deteriorated after storage, particularly after high temperature storage. There's a problem.
The present invention has been made in view of the above problems, and has as its object to achieve an increase in capacity of an alkaline dry battery and to prevent a decrease in heavy load characteristics after storage.
[0006]
[Means for Solving the Problems]
The present invention has achieved the above problems by improving the positive electrode can. That is, the present invention provides a bottomed cylindrical positive electrode can also serving as a positive electrode terminal, a hollow cylindrical positive electrode mixture disposed in the positive electrode can, and a hollow portion of the positive electrode mixture via a bottomed cylindrical separator. An alkaline dry battery comprising a gelled zinc negative electrode filled with a nickel-silver alloy-plated layer, or a nickel-plated layer on one surface of a cold-rolled steel sheet material in which nickel-plated layers are previously formed on both surfaces. A chromium alloy plating layer is formed, and a press-drawn and ironed can is used so that the surface becomes an inner surface.
[0007]
In the positive electrode can used in the alkaline dry battery of the present invention, the nickel-silver alloy plating layer or the nickel-chromium alloy plating layer formed on the inner surface thereof has an uneven surface formed by extremely fine cracks generated during press drawing and ironing. Therefore, the contact area with the positive electrode mixture or the conductive film is increased, and the internal resistance of the battery is reduced. On the other hand, since a nickel plating layer is further formed below the nickel-silver alloy plating layer or the nickel-chromium alloy plating layer, even if these layers crack, the iron base is less exposed. Therefore, the contact resistance between the positive electrode mixture and the conductive coating does not increase due to the oxidation of iron during high-temperature storage, and deterioration of heavy load characteristics after high-temperature storage is small.
[0008]
Since the alkaline dry battery of the present invention has such characteristics, the amount of manganese dioxide in the positive electrode mixture is increased, and as a result, even if the graphite powder content is 8 wt% or less, there is no problem as in the related art. High capacity can be achieved.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
(Example 1)
First, a nickel-silver alloy plating layer having a thickness of 1 to 2 μm was further formed on one surface of a cold-rolled steel sheet material having a nickel plating layer having a thickness of 1 to 2 μm formed on both surfaces in advance. Using this steel plate, a positive electrode can was formed by press-drawing and ironing into a cylindrical shape with a bottom so that the nickel-silver alloy plating layer surface was on the inside. FIG. 2 shows the configuration of the plating layer of this positive electrode can. As shown in this figure, a nickel plating layer 10 having a thickness of 1 to 2 μm is formed on a steel plate 9 of a positive electrode can, and a nickel-silver alloy plating layer having a thickness of 1 to 2 μm A layer 11 is formed.
[0010]
A conductive coating mainly composed of graphite powder was formed on the inner surface of the thus-formed positive electrode can except for the portion in contact with the gasket in the opening. The conductive coating is applied by diluting a conductive coating mainly composed of graphite powder with a low-boiling organic solvent such as methyl ethyl ketone, and applying it to the inside of the positive electrode can in the form of a mist using a spray gun. Do not apply to the part of the part that contacts the gasket. After applying the conductive paint with a spray gun, the solvent is evaporated with a dryer. The thickness of the remaining conductive film is desirably about 1 to 10 μm. FIG. 3 shows the configuration of the plating layer of this positive electrode can. In FIG. 3, reference numeral 12 denotes a conductive film.
[0011]
Using the positive electrode can having the conductive coating shown in FIG. 3, the JIS standard LR6 (AA) alkaline dry battery shown in FIG. 1 was assembled. In FIG. 1, reference numeral 1 denotes a bottomed cylindrical positive electrode can also serving as a positive electrode terminal manufactured by the above-described method, and three positive electrode materials 2 formed into a cylindrical shape by pressure are divided into the positive electrode can. Have been. The positive electrode mixture 2 is a mixture of manganese dioxide powder and graphite powder, which is formed into a hollow cylindrical shape at a predetermined pressure using a molding die. The positive electrode mixture is used to increase the discharge capacity. The graphite powder content in the sample No. 2 was 8 wt%.
[0012]
In the hollow portion of the positive electrode mixture 2, a bottomed cylindrical separator 3 made of a nonwoven fabric of acetalized polyvinyl alcohol fiber is disposed. The separator 3 is filled with a gelled zinc negative electrode 4 made of a non-melted zinc alloy powder, an alkaline electrolyte and polyacrylic acid as a gelling agent. In the gelled zinc negative electrode 4, a negative electrode current collector rod 5 made of brass is mounted so that its tip is inserted into the gelled negative electrode 4. An insulating gasket 6 made of a double annular polyamide resin is disposed on the upper outer periphery of the negative electrode current collector rod 5 and on the upper inner peripheral surface of the positive electrode can 1. A ring-shaped metal plate 7 is disposed between the double annular portions of the insulating gasket 6, and a cap-shaped metal sealing plate 8 serving also as a negative electrode terminal is provided on the head of the current collecting rod 5 on the metal plate 7. It is arranged to abut. The inside edge of the positive electrode can 1 is sealed by the gasket 6 and the metal sealing plate 8 by bending the opening edge of the positive electrode can 1 inward.
[0013]
(Example 2)
A JIS standard LR6 type (AA) alkaline dry battery was assembled in exactly the same manner as in Example 1 except that a nickel-chromium alloy plating layer of 1 to 2 μm was formed instead of the nickel-silver alloy plating layer of Example 1. .
[0014]
(Example 3)
A JIS standard LR6 type (AA) alkaline dry battery was assembled in the same manner as in Example 1 except that a conductive film mainly composed of graphite powder was not formed.
[0015]
(Example 4)
A JIS standard LR6 type (AA) alkaline dry battery was assembled in the same manner as in Example 2 except that a conductive film mainly composed of graphite powder was not formed.
[0016]
(Comparative Example 1)
A cold-rolled steel sheet material having a nickel plating layer having a thickness of 1 to 2 μm formed on both surfaces in advance was press-drawn and ironed into a cylindrical shape with a bottom, and a conductive coating mainly composed of graphite powder was formed on the inner surface. This was used as a positive electrode can, and JIS standard LR6 type (AA) alkaline dry batteries were assembled in the same manner as in Example 1 except for the above.
[0017]
(Comparative Example 2)
After cold-rolled steel sheet is pressed and drawn into a cylindrical shape with a bottom, a nickel plating layer with a thickness of 1 to 2 μm is formed, and a conductive coating mainly composed of graphite powder is formed on the inner surface. Was used as a positive electrode can, and JIS standard LR6 type (AA) alkaline dry battery was assembled in the same manner as in Example 1 except for the above.
[0018]
(Comparative Example 3)
A JIS standard LR6 type (AA) alkaline dry battery was assembled in the same manner as in Comparative Example 1 except that a conductive coating mainly composed of graphite powder was not formed on the inner surface.
[0019]
(Comparative Example 4)
A JIS standard LR6 type (AA) alkaline dry battery was assembled in the same manner as in Comparative Example 2 except that a conductive coating mainly composed of graphite powder was not formed on the inner surface.
[0020]
The internal resistance and discharge capacity at 20 ° C. of each of the LR6 type alkaline dry batteries of Examples 1 to 4 and Comparative Examples 1 to 4 assembled as described above after being stored at 60 ° C. for 0, 10, and 60 days. And the results are shown in Table 1. The internal resistance (mΩ) was measured for each of ten batteries using an AC resistance meter of 1 kHz, and the average value thereof was shown. As for the discharge capacity, a 2Ω continuous discharge test was performed for each of 10 batteries, and the average value of the duration (min) up to a final voltage of 0.9 V was shown.
[0021]
[Table 1]

[0022]
As is clear from the above table, in Examples 1 to 4, the increase in the internal resistance of the battery was small even after storage at 60 ° C. for 60 days, and the deterioration in the discharge capacity was also small, as compared with Comparative Examples 1 to 4. I understand.
[0023]
【The invention's effect】
As described above, the alkaline dry battery of the present invention has high capacity, excellent heavy load characteristics, and excellent storage characteristics.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an alkaline dry battery according to one embodiment of the present invention.
FIG. 2 is a layer configuration diagram of a positive electrode can in an example of the present invention.
FIG. 3 is a layer configuration diagram of a positive electrode can in another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Positive electrode can, 2 ... Positive electrode mixture, 3 ... Separator, 4 ... Gel zinc negative electrode, 5 ... Negative electrode current collecting rod, 6 ... Insulating gasket, 7 ... Ring-shaped metal plate, 8 ... Metal sealing plate, 9 ... Steel plate, 10: nickel plating layer, 11: nickel-silver alloy plating layer, 12: conductive coating layer mainly composed of graphite powder.

Claims

A bottom-filled cylindrical positive electrode can also serving as a positive electrode terminal, a hollow cylindrical positive electrode mixture disposed in the positive electrode can, and a gel filled in the hollow portion of the positive electrode mixture via a bottomed cylindrical separator. An alkaline dry battery comprising a zinc negative electrode and a nickel-silver alloy plating layer or a nickel-chromium alloy plating layer on one surface of a cold-rolled steel sheet material having nickel plating layers formed on both surfaces in advance as the positive electrode can. An alkaline dry battery using a can formed and pressed and ironed so that the surface is an inner surface.

2. The alkaline dry battery according to claim 1, wherein a conductive coating mainly composed of graphite powder is further formed on the inner surface of the positive electrode can.

3. The alkaline dry battery according to claim 1, wherein the graphite powder content in the positive electrode mixture is 8 wt% or less.