JP3935005B2

JP3935005B2 - Alkaline battery and manufacturing method thereof

Info

Publication number: JP3935005B2
Application number: JP2002204149A
Authority: JP
Inventors: 範幸伊東; 三七十郎牛島; 真一岩本; 哲夫伊津
Original assignee: Hitachi Maxell Energy Ltd
Current assignee: Maxell Ltd
Priority date: 2002-07-12
Filing date: 2002-07-12
Publication date: 2007-06-20
Anticipated expiration: 2022-07-12
Also published as: CN1825669A; CN1956246A; CN100413133C; CN100456539C; JP2004047321A

Description

【０００１】
【発明の属する技術分野】
本発明は、アルカリ電池とその製造方法に関し、より詳しくは、負荷特性に優れる一方で、異常発生時の発熱挙動を抑制したアルカリ電池とその製造方法に関する。
【０００２】
【従来の技術】
亜鉛を負極活物質とするアルカリ電池は、各種電子機器の電源として用いられ、その用途に応じて種々の特性が要求されている。特に、近年普及が著しいデジタルカメラにおいては、撮影可能枚数をできるだけ多くするためには、電池の高容量化と大電流放電特性などの負荷特性のさらなる向上が必要であり、その要求を満たすことのできる電池設計が検討されている。
【０００３】
電池の高容量化のためには、活物質の充填量の増加が必要であるが、活物質が放電に有効に利用されなければ容量増に結びつかないため、単に、活物質の充填量を多くするのみでは目的を達することはできない。放電容量は活物質の利用率との兼ね合いで決定されるものであるから、活物質相互の良好な導電性の確保と均質な充填が重要となる。
【０００４】
また、負荷特性の向上には、活物質の反応面積の増加や導電性の向上などが必要となるが、活物質の反応面積の増加に伴い、電解液との反応によるガス発生が生じやすくなるため、負極においては、負極活物質である亜鉛とガス発生を抑制できる添加元素とを合金化させるのが一般的である。
【０００５】
【発明が解決しようとする課題】
しかしながら、添加元素の含有量の増加により、導電性が低下しやすくなるため、ガス発生の抑制と負荷特性を両立させることは困難である。しかも、自己放電の抑制のために、電解液には亜鉛化合物、特に、酸化亜鉛を含有させるのが一般的であるが、これによっても負荷特性は低下してしまう。
【０００６】
また、たとえ負荷特性に優れる電池を設計できたとしても、以下に示す別の問題が生じるため、実用的な電池とするには解決すべき課題が残されている。すなわち、高温で貯蔵した場合の貯蔵性が悪かったり、電子機器の誤作動や誤って電池を短絡させるなどして電池に過大な電流が流れた際に、電池内で発生する熱により電池が高温となり、電解液の漏出や電池の破裂などの危険性が生じることが問題となる。特に、電池が高容量化、高負荷対応となるほど反応性が高まり、かつ発熱量が大きくなるため、上記問題の解決はより重要となる。
【０００７】
従って、高容量で負荷特性に優れる一方で、貯蔵性に優れ、短絡などの異常発生時には、発熱による急激な温度上昇などの異常挙動が生じにくいアルカリ電池を設計することが求められているのである。
【０００８】
本発明は、上記課題を解決するためになされたもので、負荷特性に優れ、電解液との反応によるガス発生や貯蔵性の低下を防止する一方で、異常発生時の発熱挙動を抑制したアルカリ電池およびその製造方法を提供するものである。
【０００９】
【課題を解決するための手段】
本発明のアルカリ電池は、二酸化マンガンおよびニッケル酸化物の少なくとも一方と導電剤と水酸化カリウムを溶解したアルカリ電解液（Ａ）とを含有する正極合剤、セパレータ、および亜鉛合金粉末とゲル化剤と水酸化カリウムを溶解したアルカリ電解液（Ｂ）とを含有する負極合剤を外装体内部に封入し、水酸化カリウムを溶解させたアルカリ電解液（Ｃ）を外装体内部に注入してセパレータに吸収させることにより作製されるアルカリ電池であって、前記正極合剤のアルカリ電解液（Ａ）の水酸化カリウム濃度が４５質量％以上であり、前記負極合剤のアルカリ電解液（Ｂ）の水酸化カリウム濃度が３５質量％以下であり、前記外装体内部に注入するアルカリ電解液（Ｃ）の水酸化カリウム濃度が２０〜４０質量％であり、アルカリ電解液（Ａ）〜（Ｃ）のうち、少なくとも１つが亜鉛化合物を含有していることを特徴とするものである。
【００１０】
また、本発明のアルカリ電池の別の態様は、二酸化マンガンおよびニッケル酸化物の少なくとも一方と導電剤と水酸化カリウムを溶解したアルカリ電解液（Ａ）とを含有する正極合剤、セパレータ、および亜鉛合金粉末とゲル化剤と水酸化カリウムを溶解したアルカリ電解液（Ｂ）とを含有する負極合剤を外装体内部に封入することにより作製されるアルカリ電池であって、前記正極合剤のアルカリ電解液（Ａ）の水酸化カリウム濃度が４５質量％以上であり、前記負極合剤のアルカリ電解液（Ｂ）の水酸化カリウム濃度が３５質量％以下であり、前記正極の導電剤として黒鉛を用い、二酸化マンガンおよびニッケル酸化物に対する黒鉛の割合を６〜８．５質量％としたことを特徴とするものである。
【００１１】
さらに本発明は、二酸化マンガンおよびニッケル酸化物の少なくとも一方と導電剤と水酸化カリウムを溶解したアルカリ電解液（Ａ）とを含有する正極合剤を外装体内部に配置する工程、前記正極合剤の内側にセパレータを配置する工程、２０〜４０質量％の濃度で水酸化カリウムを溶解させたアルカリ電解液（Ｃ）を外装体内部に注入する工程、および亜鉛合金粉末とゲル化剤と水酸化カリウムを溶解したアルカリ電解液（Ｂ）とを含有する負極合剤を前記セパレータの内側の空隙に充填する工程を有するアルカリ電池の製造方法であって、前記アルカリ電解液（Ａ）の水酸化カリウム濃度を５０質量％超とし、前記アルカリ電解液（Ｂ）の水酸化カリウム濃度を３５質量％以下としたことを特徴とするアルカリ電池の製造方法を提供するものである。
【００１２】
【発明の実施の形態】
本発明は、正極合剤の形成において水酸化カリウムを４５質量％以上の高濃度で含有するアルカリ電解液（Ａ）を用いることを第１の特徴とする。正極合剤は、二酸化マンガンおよびニッケル酸化物の少なくとも一方と導電剤と上記アルカリ電解液（Ａ）とを混合することにより形成されるが、アルカリ電解液（Ａ）の水酸化カリウム濃度を４５質量％以上とすることにより均質な混合体が形成され、合剤の高密度での充填や合剤全体の導電性向上を可能とする。従って、電池の高容量設計を実現することができるとともに、負荷特性を向上させることも可能となる。
【００１３】
一方、正極の反応性が高められたことにより、電池が短絡した場合は、短絡発生直後の段階では過大な短絡電流が流れるが、このときに生じる負極の亜鉛合金粉末の急激な放電反応により、反応を抑制する酸化物層が亜鉛合金粉末表面に一気に形成されることになり、短時間のうちに短絡電流は減少する。このため、放電に伴う発熱は比較的少なくなり、電池の温度上昇が抑制されて、電解液の漏出や電池の破裂などの異常な挙動が生じるのを防ぐことができると考えられる。ここで、上記電解液として５０質量％を超える濃度で水酸化カリウムを含有したアルカリ電解液を用いれば、上記効果がより得られやすくなる他、後述する負極合剤のアルカリ電解液（Ｂ）として、より水酸化カリウム濃度の低いものを使用することができるので、本発明においては特に望ましい結果が得られる。
【００１４】
ただし、室温での水酸化カリウムの飽和濃度がおよそ５０質量％であることから、これより高い濃度のアルカリ電解液を用いる場合は、合剤の温度管理を行うことが望ましい。すなわち、アルカリ電解液の調製は、通常、水酸化カリウムが溶解しやすいように加温された条件下で行われるため、５０質量％を超える濃度の水酸化カリウム水溶液を作製することは容易であるが、合剤の作製を室温付近かそれ以下で行う場合は、その温度での飽和量を超えた水酸化カリウムが析出し、均質な合剤の形成が損なわれる可能性が高い。そのため、電解液が飽和濃度に達しないよう加温雰囲気下で合剤構成物を混合し、正極合剤を作製することが望ましい。温度条件としては、水酸化カリウムの飽和溶解量を高めるため、３５℃以上で行うことが望ましく、水分の蒸発により電解液組成が変化するのを防ぐため、７０℃以下の温度で行うことが望ましい。また、水酸化カリウム濃度が４５〜５０質量％である場合も、加温雰囲気下で合剤構成物を混合することにより、構成物の分散性が向上して均質な合剤が形成されやすくなる。
【００１５】
また、上記導電剤としては、黒鉛、アセチレンブラック、カーボンブラック、繊維状炭素などの炭素材料を主として用いることができるが、中でも黒鉛が好ましく用いられる。本発明においては、正極の活物質として、二酸化マンガン、あるいは、オキシ水酸化ニッケルやそのニッケルの一部が他の元素で置換された化合物に代表されるニッケル酸化物のいずれか一方かあるいはそれらを混合して用いるが、正極活物質である二酸化マンガンおよびニッケル酸化物の合計量に対し、６質量％以上の割合で黒鉛を混合することが望ましい。これは、前述した短絡時の異常発熱を抑制する効果が一段と発揮されやすくなるからである。一方、活物質充填量の低下は好ましくないため、黒鉛の割合は８．５質量％以下にすることが望ましい。
【００１６】
上記以外の構成要素として、正極合剤にカルボキシメチルセルロース、メチルセルロース、ポリアクリル酸塩、ポリテトラフルオロエチレン、ポリエチレンなどのバインダを少量含有させることもできる。添加量が多いと導電性が低下するなどの弊害が生じるが、少量であれば導電剤と活物質との接触を良好にするので却って好都合である。
【００１７】
また、本発明は、負極合剤の形成において、水酸化カリウムを３５質量％以下の濃度で含有するアルカリ電解液（Ｂ）を用いることを第２の特徴とする。負極合剤は、亜鉛合金粉末とゲル化剤と水酸化カリウムを溶解したアルカリ電解液（Ｂ）とを混合し、ゲル状の混合体として形成されるが、アルカリ電解液（Ｂ）の水酸化カリウム濃度を３５質量％以下とすることにより、亜鉛合金粉末表面の酸化物被膜の状態を適切なものとすることができ、アルカリ電解液の伝導度を上げて負荷特性を向上させ、また、短絡時の初期段階で放電反応が容易に進行するため、前述した異常発熱の抑制効果が得られやすくなると思われる。
【００１８】
特に、亜鉛合金粉末の合金元素としてインジウム、ビスマスおよびアルミニウムを含有していることが望ましい。亜鉛合金粉末の表面状態をより好適なものとすることができ、負荷特性や異常発熱の抑制効果に影響をおよぼすだけでなく、亜鉛合金粉末の反応面積を増加させるために微小粒子の割合を多くする場合でも、電解液との反応を抑制しガス発生を防ぐことができるからである。これら元素の含有量としては、インジウム、ビスマスおよびアルミニウムが、それぞれ０．０３〜０．０７質量％、０．００７〜０．０２５質量％および０．００１〜０．００４質量％であるのが望ましい。また、微小粒子の割合としては、２００メッシュのふるい目を通過する粉末の割合が４質量％以上であれば、大電流のパルス放電での特性がより向上するので好ましく、１５質量％以上がより望ましい。一方、均質で流動性の良好な負極合剤を形成するためには４０質量％以下にすることが望ましい。
【００１９】
また、アルカリ電解液（Ｂ）に亜鉛化合物を含有させることによっても、亜鉛合金粉末の表面状態をより好適なものとすることができる。亜鉛化合物としては、酸化亜鉛、ケイ酸亜鉛、チタン酸亜鉛、モリブデン酸亜鉛などを用いることができ、酸化亜鉛が好適に用いられる。亜鉛化合物の溶解度を高めるためには、アルカリ電解液（Ｂ）の水酸化カリウム濃度を２０質量％以上とすることが望ましい。なお、正極合剤のアルカリ電解液（Ａ）あるいは後述するアルカリ電解液（Ｃ）に亜鉛化合物を含有させることもできる。
【００２０】
上記以外の構成要素として、負極合剤に酸化インジウムなどのインジウム化合物、酸化ビスマスなどのビスマス化合物を少量含有させることもできる。これらの化合物を含有させた場合、亜鉛合金粉末と電解液との反応によるガス発生をより効果的に防ぐことができるが、負荷特性を低下させるおそれがあるので、必要に応じて含有量が決定される。
【００２１】
本発明のアルカリ電池は、上記正極合剤および負極合剤をセパレータと共に外装体内部に封入することにより作製される。ただし、上記正極合剤および負極合剤に含有されるアルカリ電解液のみでは液量が不足する場合が多く、この場合は、さらに電解液を注入してセパレータに吸収させる工程が必要となる。このとき注入されるアルカリ電解液（Ｃ）は、２０〜４０質量％の濃度で水酸化カリウムを溶解させたものが好ましく用いられる。すなわち、前述した短絡時の異常発熱を抑制する効果は、アルカリ電解液（Ｃ）の水酸化カリウム濃度にも依存するのであり、できるだけ低い濃度の電解液を用いることが望ましく、３５質量％未満であればより好ましい結果が得られる。一方、組み立て後に、電池系内のアルカリ電解液（Ａ）〜（Ｃ）は拡散して混じりあい、徐々に一様な電解液に近づいていくが、このとき、アルカリ電解液全体の水酸化カリウムの平均濃度が好適な範囲となるよう、アルカリ電解液（Ａ）〜（Ｃ）のそれぞれの水酸化カリウム濃度を調整しておくことが望ましく、アルカリ電解液（Ｃ）には２０質量％以上の濃度で水酸化カリウムを含有させておくことが望ましい。
【００２２】
また、アルカリ電解液（Ｂ）だけでなく（Ａ）および（Ｃ）にも亜鉛化合物を含有させれば、電池を高温で貯蔵したときの特性劣化を低減する効果が大きくなる。アルカリ電解液（Ｃ）の水酸化カリウム濃度を２０質量％以上にしておけば、亜鉛化合物の溶解度が高まるため、亜鉛化合物の添加の面からも好都合である。
【００２３】
上記、アルカリ電解液全体の水酸化カリウムの平均濃度としては、３０〜３７質量％となるように電池を設計するのが望ましい。水酸化カリウム濃度を３０質量％以上とすることにより高温で貯蔵した際の貯蔵性が向上し、３３．５質量％以上であればより優れた特性が得られる。一方、３７質量％以下とすることにより負荷特性が向上し、また、短絡時の異常発熱の抑制効果が得られやすくなるからである。
【００２４】
本発明では、電池の形状などは特に限定されないが、外装体として円筒形の金属製外装缶を用いる場合は、リング状に成形された前記正極合剤を外装缶内部に配置し、その内側にコップ状のセパレータを配置し、次いで、アルカリ電解液（Ｃ）を注入してセパレータに吸収させ、さらに前記負極合剤をセパレータの内側の空隙に充填し、これら構成要素を外装缶内部に封入することにより電池が組み立てられる。図２に示されるように、円筒形のアルカリ電池においては、外装缶１の開口端部１ａを内方に折り曲げて封口を行った際に、負極端子板２０７の変形を防ぎ、かつ封口体６を内側から支える指示手段として金属ワッシャ９（円板状の金属板）を用いることが一般に行われているが、封口部分１０の占める体積が大きくなってしまうという問題がある。
【００２５】
一方、金属ワッシャをなくし、封口体６を内側から支える指示手段として負極端子板７を利用した図１の電池では、封口部分１０の占める体積を減少させることができるので、正極２および負極４の合剤の充填量をより高めることができる反面、電池の高容量化に伴い、短絡時の発熱は一層大きくなる。しかし、このような高容量設計の電池においても、本発明を用いることにより、電池の異常発熱挙動を防ぐことができるので、電池の実用性を高めることができる。
【００２６】
【実施例】
以下において本発明の実施例を説明するが、もちろん本発明はこれらの実施例に限定されるものではない。
【００２７】
（実施例１）
電解二酸化マンガン、黒鉛、ポリテトラフルオロエチレン粉末およびアルカリ電解液（Ａ）（酸化亜鉛を２．９質量％含有した５６質量％水酸化カリウム水溶液）を８７．６：６．７：０．２：５．５の質量比で混合し、正極合剤を作製した。この正極合剤の作製は５０℃の温度下で行った。また、上記正極合剤中、二酸化マンガンに対する黒鉛の割合は７．６質量％であった。
【００２８】
また、インジウム、ビスマスおよびアルミニウムをそれぞれ０．０５質量％、０．０５質量％および０．００５質量％の割合で含有する亜鉛合金粉末、ポリアクリル酸ソーダ、ポリアクリル酸およびアルカリ電解液（Ｂ）（酸化亜鉛を２．２質量％含有した３２質量％水酸化カリウム水溶液）を３９：０．２：０．２：１８の質量比で混合し、ゲル状の負極合剤を作製した。なお、上記亜鉛合金粉末は、平均粒径が１２２μｍで、８０メッシュのふるい目を全て通過し、かつ２００メッシュのふるい目を通過しない亜鉛合金粉末であって、その見掛け密度は２．６５ｇ／ｃｍ^３であった。
【００２９】
外装体として、封口部分１０の厚みが０．２５ｍｍで、胴部分２０の厚みが０．１６ｍｍに加工され、また、電池を落下させたときに正極端子１ｂのへこみを防ぐために、正極端子部分の缶厚を胴部分２０より多少厚くしたキルド鋼板製の単三形アルカリ乾電池用外装缶１を用い、以下のようにしてアルカリ電池を作製した。
【００３０】
上記正極合剤１１ｇを、内径９．１ｍｍ、外径１３．７ｍｍ、高さ４１．７ｍｍの円筒状に加圧成形して正極とし、これを上記外装缶１に挿入した。その後、外装缶１の開口端から高さ方向において３．５ｍｍの位置にグルーブを施し、外装缶１と封口体６との密着性を向上させるために、このグルーブ位置まで外装缶１の内側にピッチを塗布した。
【００３１】
次に、厚みが１００μｍで目付が３０ｇ／ｍ^２のアセタール化ビニロンとテンセルからなる不織布を三重に重ねて筒状に巻き、底部になる部分を折り曲げてこの部分を熱融着し、一端が閉じられたコップ状のセパレータ３とした。このセパレータ３を、外装缶内に挿入された正極１の内側に装填し、さらに、アルカリ電解液（Ｃ）（酸化亜鉛を２．２質量％含有した３２質量％水酸化カリウム水溶液）１．３５ｇを外装缶内に注入してセパレータ３にしみこませた。次いで、上記負極合剤５．７４ｇをセパレータ３の内側に充填して負極４とし、さらに、ナイロン６−６製の封口体６と組み合わされ、かつ打ち抜き・プレス加工により形成された厚さ０．４ｍｍの負極端子板７（ニッケルメッキ鋼板製）に溶接により取り付けられた負極集電棒５（表面がスズメッキされた真鍮製）を上記負極中央部に差し込み、外装缶１の開口端部１ａの外側からスピニング方式によりかしめることにより、図１に示す単３形アルカリ電池を作製した。なお、外装缶１の開口端と負極端子板７との間には、短絡防止のために絶縁板８を装着した。
【００３２】
上記電池において、組み立て後の電池系内のアルカリ電解液は、平均して３５質量％の水酸化カリウムを含有していた。
【００３３】
（実施例２）
電解二酸化マンガン、黒鉛、ポリテトラフルオロエチレン粉末およびアルカリ電解液（Ａ）を８９．３：５．１：０．２：５．６の質量比で混合し、正極合剤を作製した以外は実施例１と同様にして、単３形アルカリ電池を作製した。この正極合剤において、二酸化マンガンに対する黒鉛の割合は５．７質量％であった。
【００３４】
（実施例３）
アルカリ電解液（Ｂ）および（Ｃ）として、酸化亜鉛を２．０質量％含有した３０質量％水酸化カリウム水溶液を用いた以外は実施例１と同様にして、単３形アルカリ電池を作製した。組み立て後の電池系内のアルカリ電解液は、平均して３３質量％の水酸化カリウムを含有していた。
【００３５】
（実施例４）
負極の亜鉛合金粉末としてインジウム、ビスマスおよびアルミニウムをそれぞれ０．０５質量％、０．０１５質量％および０．００３質量％の割合で含有し、平均粒径が２００μｍで、３５メッシュのふるい目を全て通過し、かつ２００メッシュのふるい目を通過するものの割合が６質量％であって、見掛け密度が２．９ｇ／ｃｍ^３である亜鉛合金粉末を用いた以外は実施例１と同様にして、単３形アルカリ電池を作製した。
【００３６】
（実施例５）
負極の亜鉛合金粉末として、平均粒径が１３５μｍで、３５メッシュのふるい目を全て通過し、かつ２００メッシュのふるい目を通過するものの割合が２０質量％であって、見掛け密度が２．９ｇ／ｃｍ^３である亜鉛合金粉末を用いた以外は実施例１と同様にして、単３形アルカリ電池を作製した。
【００３７】
（比較例１）
アルカリ電解液（Ｂ）および（Ｃ）として、酸化亜鉛を２．４質量％含有した３６質量％水酸化カリウム水溶液を用いた以外は実施例１と同様にして、単３形アルカリ電池を作製した。組み立て後の電池系内のアルカリ電解液は、平均して３９質量％の水酸化カリウムを含有していた。
【００３８】
（比較例２）
アルカリ電解液（Ａ）として、酸化亜鉛を２．９質量％含有した４２質量％水酸化カリウム水溶液を用いた以外は実施例１と同様にして、単３形アルカリ電池を作製した。組み立て後の電池系内のアルカリ電解液は、平均して３２質量％の水酸化カリウムを含有していた。
【００３９】
（比較例３）
負極の亜鉛合金粉末として、平均粒径が１９５μｍで、３５メッシュのふるい目を全て通過し、かつ２００メッシュのふるい目を通過しない亜鉛合金粉末であって、見掛け密度が２．６５ｇ／ｃｍ^３である粉末を用いた以外は比較例１と同様にして、単３形アルカリ電池を作製した。
【００４０】
以上のようにして作製した実施例および比較例に係る電池各々１２個に対し、ベース放電電流を０．５Ａとし、３０秒間隔で２Ａのパルス電流を２秒間流すパルス放電試験を行い、２Ａのパルス電流が流れた時点の電圧が１．０Ｖ以下に低下するまでに要するパルス放電の回数を測定して平均値を求め、負荷特性を評価した。
【００４１】
また、上記とは別の電池各々１２個に対し、電池の外装缶側面の中央部にアルミニウム製のテープで熱伝対を固定し、電池を短絡させたときの外装缶表面温度を測定して平均値を求め、異常発生時の発熱挙動を評価した。このとき、実施例３および比較例１の電池については電流値の時間変化も測定した。短絡電流および外装缶表面温度の短絡開始からの変化を、実施例３の電池については図３に、比較例１の電池については図４に示した。
【００４２】
さらに、別の電池各々２４個に対し、まず、１２個を１Ａの放電電流で放電させて０．９Ｖ以下になるまでの放電時間を測定し、その平均時間を保存前の放電時間とし、次に、残り１２個を６０℃の恒温槽中に２０日間保存し、取り出してから１日室温で冷却後、同じく１Ａの放電電流で放電させて０．９Ｖ以下になるまでの放電時間を測定し、その平均時間を保存後の放電時間とし、保存前の放電時間に対する保存後の放電時間の割合を容量保持率として求め、高温での電池の貯蔵性を評価した。上記パルス放電の回数、外装缶表面温度および容量保持率の測定結果を表１にまとめて示した。なお、ガス発生は特に問題にはならなかった。
【００４３】
【表１】

【００４４】
表１の結果より明らかなように、本発明の実施例の電池は、負荷特性が優れ、異常発生時の発熱挙動が抑制されており、高温での貯蔵性にも優れていた。特に、正極合剤中、二酸化マンガンに対する黒鉛の割合を６〜８．５質量％の範囲内とし、電池系内のアルカリ電解液の水酸化カリウム濃度を平均して３３．５質量％以上とした実施例１の電池は、黒鉛の割合が上記より少ない実施例２の電池よりも外装缶表面温度を低下させることができ、水酸化カリウム濃度が上記よりも低い実施例３の電池よりも容量保持率を向上させることができた。
【００４５】
また、亜鉛合金粉末中に２００メッシュ以下の粉末を６質量％含み、微小粒子の割合が実施例１よりも多い実施例４の電池では、インジウム、ビスマスおよびアルミニウムの含有割合が最適化されることによって、外装缶表面温度の上昇や容量保持率の低下を招くことなくパルス放電の回数を増加させることができた。さらに微小粒子の割合を増やした実施例５の電池では、外装缶表面温度は上昇したものの、パルス放電の回数をさらに増加させることができた。
【００４６】
一方、負極合剤のアルカリ電解液（Ｂ）の水酸化カリウム濃度を３５質量％より高くした比較例１の電池は、３５〜８０メッシュの粒度の粉末をカットすることによって比較例３の電池よりも亜鉛合金粉末中の微小粒子の割合が高くなっているため、実施例１と同様に比較例３よりもパルス放電の回数を増加させることができたが、実施例１の電池よりも外装缶表面温度が大幅に上昇した。また、正極合剤のアルカリ電解液（Ａ）の水酸化カリウム濃度を４５質量％より低くした比較例２の電池は、容量保持率が大幅に低下してしまい、いずれも実用的な特性とならなかった。
【００４７】
【発明の効果】
負荷特性に優れ、電解液との反応によるガス発生や貯蔵性の低下を防止する一方で、異常発生時の発熱挙動を抑制したアルカリ電池およびその製造方法を提供することができる。
【図面の簡単な説明】
【図１】封口体を内側から支える指示手段として負極端子板を利用したアルカリ電池の全体構造を示す断面図である。
【図２】従来のアルカリ電池の一般的な構造を示す断面図である。
【図３】本発明の実施例３のアルカリ電池を短絡させた際の、短絡電流および外装缶表面温度の変化を示すグラフである。
【図４】本発明の比較例１のアルカリ電池を短絡させた際の、短絡電流および外装缶表面温度の変化を示すグラフである
【符号の説明】
１外装缶
１ａ外装缶の開口端部
２正極
３セパレータ
４負極
５負極集電棒
６封口体
７、２０７負極端子板
８絶縁板
９金属ワッシャ
１０封口部分
２０胴部分[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an alkaline battery and a method for manufacturing the same, and more particularly to an alkaline battery that has excellent load characteristics and suppresses heat generation behavior when an abnormality occurs and a method for manufacturing the same.
[0002]
[Prior art]
An alkaline battery using zinc as a negative electrode active material is used as a power source for various electronic devices, and various characteristics are required depending on its use. In particular, in digital cameras that have become popular in recent years, in order to maximize the number of images that can be taken, it is necessary to increase the capacity of the battery and further improve the load characteristics such as the large current discharge characteristics. Possible battery designs are being studied.
[0003]
In order to increase the capacity of the battery, it is necessary to increase the filling amount of the active material. However, if the active material is not effectively used for discharging, the capacity cannot be increased. Therefore, simply increasing the filling amount of the active material. You can't achieve your goal by just doing it. Since the discharge capacity is determined in view of the utilization factor of the active material, it is important to ensure good conductivity between the active materials and to perform uniform filling.
[0004]
Moreover, to improve the load characteristics, it is necessary to increase the reaction area of the active material and improve the conductivity, but as the reaction area of the active material increases, gas generation due to reaction with the electrolyte tends to occur. Therefore, in the negative electrode, it is common to alloy zinc, which is a negative electrode active material, with an additive element that can suppress gas generation.
[0005]
[Problems to be solved by the invention]
However, since the conductivity tends to decrease due to an increase in the content of the additive element, it is difficult to achieve both suppression of gas generation and load characteristics. Moreover, in order to suppress self-discharge, the electrolyte solution generally contains a zinc compound, particularly zinc oxide, but this also deteriorates the load characteristics.
[0006]
Even if a battery having excellent load characteristics can be designed, another problem shown below arises. Therefore, there remains a problem to be solved for a practical battery. In other words, when the battery is stored at a high temperature, the battery becomes hot due to heat generated in the battery when an excessive current flows through the battery due to malfunction of the electronic device or accidental short circuit of the battery. Thus, there arises a problem that dangers such as leakage of the electrolyte and rupture of the battery occur. In particular, the higher the capacity of the battery and the higher the load, the higher the reactivity and the greater the amount of heat generated. Therefore, the solution of the above problem becomes more important.
[0007]
Therefore, it is required to design an alkaline battery that has high capacity and excellent load characteristics, but also has excellent storability and is unlikely to cause abnormal behavior such as rapid temperature rise due to heat generation when an abnormality such as a short circuit occurs. .
[0008]
The present invention has been made in order to solve the above-described problems, and has an excellent load characteristic, an alkali that suppresses heat generation behavior at the time of occurrence of an abnormality while preventing gas generation and storage deterioration due to reaction with an electrolytic solution. A battery and a manufacturing method thereof are provided.
[0009]
[Means for Solving the Problems]
The alkaline battery of the present invention comprises a positive electrode mixture containing at least one of manganese dioxide and nickel oxide, a conductive agent and an alkaline electrolyte (A) in which potassium hydroxide is dissolved, a separator, and a zinc alloy powder and a gelling agent. And a negative electrode mixture containing an alkaline electrolyte (B) in which potassium hydroxide is dissolved, and sealed in the exterior body, and an alkaline electrolyte (C) in which potassium hydroxide is dissolved is injected into the exterior body to separate the separator. In which the potassium hydroxide concentration of the alkaline electrolyte (A) of the positive electrode mixture is 45% by mass or more, and the alkaline electrolyte (B) of the negative electrode mixture The potassium hydroxide concentration is 35% by mass or less, the potassium hydroxide concentration of the alkaline electrolyte (C) injected into the exterior body is 20 to 40% by mass, Of the liquid (A) ~ (C), those at least one, characterized by containing a zinc compound.
[0010]
Another aspect of the alkaline battery of the present invention is a positive electrode mixture containing at least one of manganese dioxide and nickel oxide, a conductive agent and an alkaline electrolyte (A) in which potassium hydroxide is dissolved, a separator, and zinc An alkaline battery prepared by enclosing a negative electrode mixture containing an alloy powder, a gelling agent, and an alkaline electrolyte (B) in which potassium hydroxide is dissolved, inside the outer package, wherein the alkali of the positive electrode mixture The potassium hydroxide concentration of the electrolytic solution (A) is 45% by mass or more, the potassium hydroxide concentration of the alkaline electrolyte (B) of the negative electrode mixture is 35% by mass or less, and graphite is used as the conductive agent of the positive electrode. The ratio of graphite to manganese dioxide and nickel oxide is 6 to 8.5% by mass.
[0011]
Furthermore, the present invention provides a step of disposing a positive electrode mixture containing at least one of manganese dioxide and nickel oxide, a conductive agent and an alkaline electrolyte (A) in which potassium hydroxide is dissolved, inside the outer package, the positive electrode mixture A step of disposing a separator inside the step, a step of injecting an alkaline electrolyte (C) in which potassium hydroxide is dissolved at a concentration of 20 to 40% by mass, and a zinc alloy powder, a gelling agent, and a hydroxide A method for producing an alkaline battery, comprising a step of filling a gap inside the separator with a negative electrode mixture containing an alkaline electrolyte (B) in which potassium is dissolved, the potassium hydroxide of the alkaline electrolyte (A) Provided is a method for producing an alkaline battery, characterized in that the concentration is more than 50% by mass and the potassium hydroxide concentration of the alkaline electrolyte (B) is 35% by mass or less. Than it is.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is characterized in that an alkaline electrolyte (A) containing potassium hydroxide at a high concentration of 45% by mass or more is used in the formation of the positive electrode mixture. The positive electrode mixture is formed by mixing at least one of manganese dioxide and nickel oxide, a conductive agent, and the alkaline electrolyte (A). The alkaline electrolyte (A) has a potassium hydroxide concentration of 45 mass. When the content is at least%, a homogeneous mixture is formed, and the mixture can be filled at a high density and the conductivity of the entire mixture can be improved. Therefore, it is possible to realize a high capacity design of the battery and to improve load characteristics.
[0013]
On the other hand, when the battery is short-circuited due to the increased reactivity of the positive electrode, an excessive short-circuit current flows immediately after the occurrence of the short-circuit, but due to the rapid discharge reaction of the zinc alloy powder of the negative electrode that occurs at this time, An oxide layer that suppresses the reaction is formed on the surface of the zinc alloy powder at once, and the short-circuit current decreases in a short time. For this reason, it is considered that the heat generated by the discharge is relatively small, the battery temperature rise is suppressed, and abnormal behavior such as leakage of the electrolytic solution or battery rupture can be prevented. Here, if the alkaline electrolyte containing potassium hydroxide at a concentration exceeding 50% by mass is used as the electrolytic solution, the above effect can be more easily obtained, and the alkaline electrolyte (B) of the negative electrode mixture described later Since a lower potassium hydroxide concentration can be used, particularly desirable results can be obtained in the present invention.
[0014]
However, since the saturation concentration of potassium hydroxide at room temperature is about 50% by mass, it is desirable to control the temperature of the mixture when using an alkaline electrolyte having a higher concentration. That is, since the preparation of the alkaline electrolyte is usually performed under conditions that are heated so that potassium hydroxide is easily dissolved, it is easy to produce a potassium hydroxide aqueous solution having a concentration exceeding 50% by mass. However, when the mixture is produced at or near room temperature, there is a high possibility that potassium hydroxide exceeding the saturation amount at that temperature will precipitate and the formation of a homogeneous mixture will be impaired. Therefore, it is desirable to mix the mixture components in a heated atmosphere so that the electrolytic solution does not reach the saturation concentration, thereby producing a positive electrode mixture. The temperature condition is preferably 35 ° C. or higher in order to increase the saturated dissolution amount of potassium hydroxide, and preferably 70 ° C. or lower in order to prevent the electrolyte composition from changing due to evaporation of moisture. . In addition, even when the potassium hydroxide concentration is 45 to 50% by mass, the dispersibility of the composition is improved and a homogeneous mixture is easily formed by mixing the mixture composition in a heated atmosphere. .
[0015]
Moreover, as said electrically conductive agent, carbon materials, such as graphite, acetylene black, carbon black, and fibrous carbon, can be mainly used, However, Among these, graphite is used preferably. In the present invention, as the positive electrode active material, either manganese dioxide, nickel oxyhydroxide or nickel oxide typified by a compound in which a part of nickel is substituted with another element, or any of them is used. Although mixed and used, it is desirable to mix graphite at a ratio of 6% by mass or more with respect to the total amount of manganese dioxide and nickel oxide as positive electrode active materials. This is because the effect of suppressing the abnormal heat generation at the time of the short circuit is more easily exhibited. On the other hand, since the reduction of the active material filling amount is not preferable, the ratio of graphite is desirably 8.5% by mass or less.
[0016]
As a constituent element other than the above, a small amount of a binder such as carboxymethyl cellulose, methyl cellulose, polyacrylate, polytetrafluoroethylene, and polyethylene can be contained in the positive electrode mixture. If the added amount is large, adverse effects such as a decrease in conductivity occur, but if the added amount is small, the contact between the conductive agent and the active material is improved, which is advantageous.
[0017]
The second feature of the present invention is that an alkaline electrolyte (B) containing potassium hydroxide at a concentration of 35% by mass or less is used in the formation of the negative electrode mixture. The negative electrode mixture is formed by mixing a zinc alloy powder, a gelling agent, and an alkaline electrolyte (B) in which potassium hydroxide is dissolved to form a gel-like mixture. By adjusting the potassium concentration to 35% by mass or less, the state of the oxide coating on the surface of the zinc alloy powder can be made appropriate, the conductivity of the alkaline electrolyte is increased, the load characteristics are improved, and the short circuit is also achieved. Since the discharge reaction proceeds easily at the initial stage of the time, it is likely that the above-described effect of suppressing abnormal heat generation is easily obtained.
[0018]
In particular, it is desirable to contain indium, bismuth and aluminum as alloy elements of the zinc alloy powder. The surface condition of the zinc alloy powder can be made more suitable, not only affecting the load characteristics and the effect of suppressing abnormal heat generation, but also increasing the proportion of fine particles to increase the reaction area of the zinc alloy powder. This is because the reaction with the electrolytic solution can be suppressed and gas generation can be prevented. As contents of these elements, indium, bismuth and aluminum are preferably 0.03 to 0.07% by mass, 0.007 to 0.025% by mass and 0.001 to 0.004% by mass, respectively. . The proportion of fine particles is preferably 4% by mass or more if the proportion of powder passing through a 200-mesh sieve is improved because the characteristics in high-current pulse discharge are further improved, and more preferably 15% by mass or more. desirable. On the other hand, in order to form a negative electrode mixture having a uniform and good fluidity, it is desirable to make it 40% by mass or less.
[0019]
Moreover, the surface state of a zinc alloy powder can be made more suitable also by making an alkaline electrolyte (B) contain a zinc compound. As the zinc compound, zinc oxide, zinc silicate, zinc titanate, zinc molybdate and the like can be used, and zinc oxide is preferably used. In order to increase the solubility of the zinc compound, the potassium hydroxide concentration of the alkaline electrolyte (B) is desirably 20% by mass or more. In addition, a zinc compound can also be contained in the alkaline electrolyte (A) of the positive electrode mixture or the alkaline electrolyte (C) described later.
[0020]
As a component other than the above, the negative electrode mixture can contain a small amount of an indium compound such as indium oxide and a bismuth compound such as bismuth oxide. When these compounds are contained, gas generation due to the reaction between the zinc alloy powder and the electrolyte can be prevented more effectively, but the load characteristics may be reduced, so the content is determined as necessary. Is done.
[0021]
The alkaline battery of the present invention is produced by enclosing the positive electrode mixture and the negative electrode mixture together with a separator in the exterior body. However, there are many cases where the amount of liquid is insufficient with only the alkaline electrolyte contained in the positive electrode mixture and the negative electrode mixture. In this case, a step of further injecting the electrolyte and causing the separator to absorb it is necessary. The alkaline electrolyte (C) injected at this time is preferably one in which potassium hydroxide is dissolved at a concentration of 20 to 40% by mass. That is, the effect of suppressing the abnormal heat generation at the time of short circuit described above also depends on the potassium hydroxide concentration of the alkaline electrolyte (C), and it is desirable to use an electrolyte having a concentration as low as possible, less than 35% by mass. If so, more favorable results can be obtained. On the other hand, after the assembly, the alkaline electrolytes (A) to (C) in the battery system are diffused and mixed, and gradually approach a uniform electrolytic solution. It is desirable to adjust the potassium hydroxide concentration of each of the alkaline electrolytes (A) to (C) so that the average concentration of is within a suitable range. It is desirable to contain potassium hydroxide at a concentration.
[0022]
Further, if the zinc compound is contained not only in the alkaline electrolyte (B) but also in (A) and (C), the effect of reducing characteristic deterioration when the battery is stored at a high temperature is increased. If the potassium hydroxide concentration of the alkaline electrolyte (C) is set to 20% by mass or more, the solubility of the zinc compound increases, which is advantageous from the viewpoint of adding the zinc compound.
[0023]
It is desirable to design the battery so that the average concentration of potassium hydroxide in the entire alkaline electrolyte is 30 to 37% by mass. When the potassium hydroxide concentration is 30% by mass or more, the storage property when stored at a high temperature is improved, and if it is 33.5% by mass or more, more excellent characteristics are obtained. On the other hand, when the content is 37% by mass or less, load characteristics are improved, and an effect of suppressing abnormal heat generation during a short circuit is easily obtained.
[0024]
In the present invention, the shape of the battery is not particularly limited. However, when a cylindrical metal outer can is used as the outer casing, the positive electrode mixture formed in a ring shape is disposed inside the outer can, and inside the outer casing can. A cup-shaped separator is placed, and then the alkaline electrolyte (C) is injected and absorbed by the separator. Further, the negative electrode mixture is filled in the gap inside the separator, and these components are sealed inside the outer can. As a result, the battery is assembled. As shown in FIG. 2, in the cylindrical alkaline battery, when the opening end 1 a of the outer can 1 is folded inward and sealed, the negative electrode terminal plate 207 is prevented from being deformed, and the sealing body 6 In general, a metal washer 9 (a disk-shaped metal plate) is used as an instruction means for supporting the seal from the inside, but there is a problem that the volume occupied by the sealing portion 10 is increased.
[0025]
On the other hand, in the battery of FIG. 1 in which the metal washer is eliminated and the negative electrode terminal plate 7 is used as an instruction means for supporting the sealing body 6 from the inside, the volume occupied by the sealing portion 10 can be reduced. On the other hand, the filling amount of the mixture can be further increased. However, as the capacity of the battery is increased, the heat generation at the time of short circuit is further increased. However, even in a battery with such a high capacity design, by using the present invention, the abnormal heat generation behavior of the battery can be prevented, so that the practicality of the battery can be enhanced.
[0026]
【Example】
Examples of the present invention will be described below. Of course, the present invention is not limited to these examples.
[0027]
Example 1
Electrolytic manganese dioxide, graphite, polytetrafluoroethylene powder and alkaline electrolyte (A) (56% by mass aqueous potassium hydroxide solution containing 2.9% by mass of zinc oxide) 87.6: 6.7: 0.2: The mixture was mixed at a mass ratio of 5.5 to prepare a positive electrode mixture. The positive electrode mixture was produced at a temperature of 50 ° C. Moreover, the ratio of the graphite with respect to manganese dioxide in the said positive electrode mixture was 7.6 mass%.
[0028]
Also, zinc alloy powder, polyacrylic acid soda, polyacrylic acid, and alkaline electrolyte (B) containing 0.05% by mass, 0.05% by mass, and 0.005% by mass of indium, bismuth, and aluminum, respectively. (A 32% by mass aqueous potassium hydroxide solution containing 2.2% by mass of zinc oxide) was mixed at a mass ratio of 39: 0.2: 0.2: 18 to prepare a gelled negative electrode mixture. The zinc alloy powder is a zinc alloy powder having an average particle size of 122 μm, passing through all 80 mesh screens and not passing through 200 mesh screens, and has an apparent density of 2.65 g / cm. ³ .
[0029]
As the exterior body, the sealing portion 10 has a thickness of 0.25 mm, the body portion 20 has a thickness of 0.16 mm, and in order to prevent the positive terminal 1b from being dented when the battery is dropped, Using an outer can 1 for AA alkaline dry batteries made of a killed steel plate having a can thickness slightly thicker than that of the barrel portion 20, an alkaline battery was produced as follows.
[0030]
11 g of the positive electrode mixture was press-molded into a cylindrical shape having an inner diameter of 9.1 mm, an outer diameter of 13.7 mm, and a height of 41.7 mm to form a positive electrode, which was inserted into the outer can 1. Thereafter, a groove is applied at a position of 3.5 mm in the height direction from the opening end of the outer can 1, and in order to improve the adhesion between the outer can 1 and the sealing body 6, the inner surface of the outer can 1 is reached to the groove position. Pitch was applied.
[0031]
Next, a nonwoven fabric made of acetalized vinylon having a thickness of 100 μm and a basis weight of 30 g / m ² and tencel is overlapped in a cylinder, wound into a cylindrical shape, the bottom portion is bent, this portion is heat-sealed, and one end is closed The cup-shaped separator 3 thus obtained was obtained. The separator 3 was loaded inside the positive electrode 1 inserted in the outer can, and further, alkaline electrolyte (C) (32% by mass potassium hydroxide aqueous solution containing 2.2% by mass of zinc oxide) 1.35 g Was poured into the outer can and soaked into the separator 3. Next, 5.74 g of the negative electrode mixture was filled into the separator 3 to form the negative electrode 4, and further combined with the sealing body 6 made of nylon 6-6 and formed by punching / pressing with a thickness of 0. A negative electrode current collector rod 5 (made of brass whose surface is tin-plated) attached to a 4 mm negative electrode terminal plate 7 (made of nickel-plated steel plate) by welding is inserted into the negative electrode central portion, and from the outside of the open end 1a of the outer can 1 The AA alkaline battery shown in FIG. 1 was produced by caulking by a spinning method. An insulating plate 8 was mounted between the open end of the outer can 1 and the negative terminal plate 7 to prevent a short circuit.
[0032]
In the above battery, the alkaline electrolyte in the assembled battery system contained 35% by mass of potassium hydroxide on average.
[0033]
(Example 2)
Conducted except that electrolytic manganese dioxide, graphite, polytetrafluoroethylene powder and alkaline electrolyte (A) were mixed at a mass ratio of 89.3: 5.1: 0.2: 5.6 to produce a positive electrode mixture. In the same manner as in Example 1, an AA alkaline battery was produced. In this positive electrode mixture, the ratio of graphite to manganese dioxide was 5.7% by mass.
[0034]
(Example 3)
AA alkaline batteries were produced in the same manner as in Example 1 except that 30% by mass potassium hydroxide aqueous solution containing 2.0% by mass of zinc oxide was used as the alkaline electrolytes (B) and (C). . The alkaline electrolyte in the assembled battery system contained 33% by mass of potassium hydroxide on average.
[0035]
Example 4
Indium, bismuth and aluminum are contained in the proportions of 0.05% by mass, 0.015% by mass and 0.003% by mass, respectively, as the zinc alloy powder of the negative electrode, the average particle size is 200 μm, and all 35 mesh sieves The ratio of those passing through and 200 mesh sieve was 6% by mass, and the zinc alloy powder having an apparent density of 2.9 g / cm ³ was used. A three-type alkaline battery was produced.
[0036]
(Example 5)
The proportion of the negative electrode zinc alloy powder having an average particle diameter of 135 μm, passing through all 35 mesh sieves and passing through 200 mesh sieves is 20% by mass, and the apparent density is 2.9 g / AA alkaline batteries were produced in the same manner as in Example 1 except that the zinc alloy powder of cm ³ was used.
[0037]
(Comparative Example 1)
AA alkaline batteries were produced in the same manner as in Example 1 except that 36 mass% potassium hydroxide aqueous solution containing 2.4 mass% of zinc oxide was used as the alkaline electrolytes (B) and (C). . The alkaline electrolyte in the assembled battery system contained 39% by mass of potassium hydroxide on average.
[0038]
(Comparative Example 2)
An AA alkaline battery was produced in the same manner as in Example 1 except that a 42% by mass potassium hydroxide aqueous solution containing 2.9% by mass of zinc oxide was used as the alkaline electrolyte (A). The alkaline electrolyte in the assembled battery system contained 32% by mass potassium hydroxide on average.
[0039]
(Comparative Example 3)
The negative electrode zinc alloy powder has an average particle size of 195 μm, passes through all 35 mesh screens, and does not pass through 200 mesh screens, and has an apparent density of 2.65 g / cm ³ . AA alkaline batteries were produced in the same manner as in Comparative Example 1 except that a certain powder was used.
[0040]
For each of the 12 batteries according to the example and the comparative example manufactured as described above, a pulse discharge test was performed in which a base discharge current was 0.5 A and a pulse current of 2 A was supplied for 2 seconds at intervals of 30 seconds. The number of pulse discharges required until the voltage at the time when the pulse current flowed decreased to 1.0 V or less was measured to obtain an average value, and the load characteristics were evaluated.
[0041]
In addition, for each of 12 batteries different from the above, a thermocouple was fixed with a tape made of aluminum at the center of the side surface of the outer can of the battery, and the surface temperature of the outer can when the battery was short-circuited was measured. The average value was obtained and the heat generation behavior when an abnormality occurred was evaluated. At this time, the time change of the current value was also measured for the batteries of Example 3 and Comparative Example 1. Changes in the short-circuit current and the outer can surface temperature from the start of the short-circuit are shown in FIG. 3 for the battery of Example 3 and in FIG. 4 for the battery of Comparative Example 1.
[0042]
Furthermore, for each of 24 batteries, first, 12 batteries were discharged with a discharge current of 1 A, and the discharge time until 0.9 V or less was measured. The average time was taken as the discharge time before storage. In addition, the remaining 12 pieces were stored in a constant temperature bath at 60 ° C. for 20 days, taken out, cooled at room temperature for 1 day, and then discharged at a discharge current of 1 A and measured for a discharge time of 0.9 V or less. The average time was taken as the discharge time after storage, the ratio of the discharge time after storage to the discharge time before storage was determined as the capacity retention, and the storability of the battery at high temperature was evaluated. Table 1 summarizes the measurement results of the number of pulse discharges, the outer can surface temperature, and the capacity retention. Gas generation was not a problem.
[0043]
[Table 1]

[0044]
As apparent from the results in Table 1, the batteries of the examples of the present invention were excellent in load characteristics, suppressed the heat generation behavior when an abnormality occurred, and were excellent in storage at high temperatures. In particular, in the positive electrode mixture, the ratio of graphite to manganese dioxide is in the range of 6 to 8.5% by mass, and the average potassium hydroxide concentration of the alkaline electrolyte in the battery system is 33.5% by mass or more. The battery of Example 1 can lower the outer can surface temperature as compared with the battery of Example 2 with a lower proportion of graphite, and retains the capacity than the battery of Example 3 with a lower potassium hydroxide concentration than the above. The rate could be improved.
[0045]
In addition, the content of indium, bismuth, and aluminum is optimized in the battery of Example 4 that contains 6% by mass of powder of 200 mesh or less in the zinc alloy powder and the ratio of fine particles is larger than that of Example 1. As a result, the number of pulse discharges could be increased without causing an increase in the outer can surface temperature and a decrease in capacity retention. Further, in the battery of Example 5 in which the proportion of fine particles was increased, the surface temperature of the outer can increased, but the number of pulse discharges could be further increased.
[0046]
On the other hand, the battery of Comparative Example 1 in which the potassium hydroxide concentration of the alkaline electrolyte (B) of the negative electrode mixture was higher than 35 mass% was cut from the powder of Comparative Example 3 by cutting powder with a particle size of 35 to 80 mesh. Since the ratio of the fine particles in the zinc alloy powder is high, the number of pulse discharges can be increased as compared with Comparative Example 3 as in Example 1, but the outer can can be increased as compared with the battery of Example 1. The surface temperature increased significantly. In addition, the battery of Comparative Example 2 in which the potassium hydroxide concentration of the alkaline electrolyte (A) of the positive electrode mixture was lower than 45% by mass greatly reduced the capacity retention rate, and all of them had practical characteristics. There wasn't.
[0047]
【The invention's effect】
It is possible to provide an alkaline battery excellent in load characteristics, preventing gas generation due to reaction with an electrolytic solution and lowering storage stability, and suppressing heat generation behavior when an abnormality occurs, and a method for manufacturing the same.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the overall structure of an alkaline battery using a negative terminal plate as an instruction means for supporting a sealing body from the inside.
FIG. 2 is a cross-sectional view showing a general structure of a conventional alkaline battery.
FIG. 3 is a graph showing changes in short circuit current and outer can surface temperature when the alkaline battery of Example 3 of the present invention is short-circuited.
FIG. 4 is a graph showing changes in short circuit current and outer can surface temperature when the alkaline battery of Comparative Example 1 of the present invention is short-circuited.
DESCRIPTION OF SYMBOLS 1 Outer can 1a Open end part of outer can 2 Positive electrode 3 Separator 4 Negative electrode 5 Negative electrode current collecting rod 6 Sealing body 7,207 Negative electrode terminal board 8 Insulating plate 9 Metal washer 10 Sealing part 20 Trunk part

Claims

A positive electrode mixture containing at least one of manganese dioxide and nickel oxide, a conductive agent and an alkaline electrolyte (A) in which potassium hydroxide is dissolved, a separator, and a zinc alloy powder, a gelling agent and potassium hydroxide are dissolved. produced by Rukoto to absorb the negative electrode mixture containing an alkaline electrolyte (B) is sealed inside the exterior body, the alkaline electrolytic solution obtained by dissolving potassium hydroxide (C) to the separator was injected inside the exterior body An alkaline battery,
The concentration of potassium hydroxide of the alkaline electrolyte (A) of the positive electrode mixture is not less than 45 mass% state, and are potassium hydroxide concentration of 35 wt% or less of the negative electrode mixture alkaline electrolyte (B), wherein The potassium hydroxide concentration of the alkaline electrolyte (C) injected into the exterior body is 20 to 40% by mass,
Of the alkaline electrolyte (A) ~ (C), alkaline batteries, characterized that you have to contain at least one zinc compound.

A positive electrode mixture containing at least one of manganese dioxide and nickel oxide, a conductive agent and an alkaline electrolyte (A) in which potassium hydroxide is dissolved, a separator, and a zinc alloy powder, a gelling agent, and potassium hydroxide are dissolved. An alkaline battery produced by enclosing a negative electrode mixture containing an alkaline electrolyte (B) inside an exterior body,
The potassium hydroxide concentration of the alkaline electrolyte (A) of the positive electrode mixture is 45% by mass or more, and the potassium hydroxide concentration of the alkaline electrolyte (B) of the negative electrode mixture is 35% by mass or less,
An alkaline battery characterized in that graphite is used as a conductive agent for the positive electrode, and the ratio of graphite to manganese dioxide and nickel oxide is 6 to 8.5% by mass.

During assembly of the battery, furthermore, according to claim 2, characterized in that imbibed alkaline electrolytic solution obtained by dissolving potassium hydroxide at a concentration of 20 to 40% by weight of (C) the injected separator inside the exterior body Alkaline battery.

The alkaline battery according to claim 3 , wherein at least one of the alkaline electrolytes (A) to (C) contains a zinc compound.

After the assembly of the battery, the potassium hydroxide concentration of each of the alkaline electrolytes (A) to (C) was adjusted so that the average potassium hydroxide concentration of the alkaline electrolyte in the battery system was 30 to 37% by mass . The alkaline battery according to claim 1, 3 or 4 .

The alkaline battery according to any one of claims 1 to 5, wherein the concentration of potassium hydroxide in the alkaline electrolyte (A) of the positive electrode mixture exceeds 50 mass %.

The alkaline battery according to any one of claims 1 to 6, wherein the concentration of potassium hydroxide in the alkaline electrolyte (B) of the negative electrode mixture is 20% by mass or more.

The alkaline battery according to any one of claims 1 to 7 , wherein the zinc alloy powder of the negative electrode contains indium, bismuth and aluminum.

It indium contained in the zinc alloy powder, the content of bismuth and aluminum, respectively 0.03 to 0.07 wt%, it is 0.007 to 0.025 wt% and 0.001 to 0.004 wt% The alkaline battery according to claim 8 .

The alkaline battery according to any one of claims 1 to 9 , wherein a zinc alloy powder in which a proportion of a powder passing through a 200 mesh sieve is 4 to 40% by mass is used as the negative electrode zinc alloy powder. .

A step of disposing a positive electrode mixture containing at least one of manganese dioxide and nickel oxide, a conductive agent and an alkaline electrolyte (A) in which potassium hydroxide is dissolved inside the exterior body, and a separator inside the positive electrode mixture The step of arranging, the step of injecting an alkaline electrolyte (C) in which potassium hydroxide is dissolved at a concentration of 20 to 40% by mass , and the alkali in which zinc alloy powder, gelling agent and potassium hydroxide are dissolved A method for producing an alkaline battery comprising a step of filling a gap inside the separator with a negative electrode mixture containing an electrolytic solution (B), wherein the alkaline electrolyte (A) has a potassium hydroxide concentration of 50 % by mass . A method for producing an alkaline battery, characterized in that the alkaline hydroxide (B) has a potassium hydroxide concentration of 35% by mass or less.

Method for producing an alkaline battery according to claim 1 1, characterized in that to form a positive electrode mixture at a temperature of 35 to 70 ° C..

After the assembly of the battery, the potassium hydroxide concentration of each of the alkaline electrolytes (A) to (C) was adjusted so that the average potassium hydroxide concentration of the alkaline electrolyte in the battery system was 30 to 37% by mass . The method for producing an alkaline battery according to claim 11 or 12 , wherein: