JP3647980B2

JP3647980B2 - Anode material for alkaline manganese batteries

Info

Publication number: JP3647980B2
Application number: JP21433596A
Authority: JP
Inventors: 秀樹永田; 健治一箭; 和也斉藤
Original assignee: Dowa Holdings Co Ltd; Dowa Mining Co Ltd
Current assignee: Dowa Holdings Co Ltd
Priority date: 1996-07-25
Filing date: 1996-07-25
Publication date: 2005-05-18
Anticipated expiration: 2016-07-25
Also published as: JPH1040926A

Description

【０００１】
【産業上の利用分野】
本発明は、アルカリ電池用電解液、アルカリ電池の負極材（負極活物質）およびアルカリ電池用負極材となる亜鉛合金粉末およびその製造方法に関する。
【０００２】
【従来の技術】
従来、アルカリ乾電池等電池の負極材としては亜鉛または亜鉛合金粉末が用いられている。亜鉛は水素過電圧が高いことや価格が比較的低廉であることから好んで負極材として用いられている。
【０００３】
この負極材に使用される電解液としては水に水酸化カリウムを４０重量％程度溶解し、さらにこの電解液に酸化亜鉛を飽和状態まで溶解したものが一般的に使用される。４０重量％程度の水酸化カリウム水溶液には室温で約７重量％の酸化亜鉛が溶解する。ここで電解液に酸化亜鉛を飽和状態まで溶解させるのは以下の理由による。
【０００４】
亜鉛は両性金属であるため４０重量％水酸化カリウム溶液のような強アルカリ電解液では下記（１）および（２）式の示すように水素ガス発生をともなって亜鉛が亜鉛酸イオンとなって溶解する。水素ガス発生量の多いゲル状負極材を電池に組み込んだ場合、発生した水素ガスが電池の内圧を上昇させ、電池内の電解液を押し上げ、保存時に電池が漏液する。
【０００５】
Ｚｎ＋４０Ｈ^- → Ｚｎ（ＯＨ）₄ ^2-＋２ｅ^- （１）
２Ｈ₂Ｏ＋２ｅ^- → Ｈ₂↑＋２ＯＨ^- （２）
そこで、電解液中に予め酸化亜鉛を飽和させておくと電解液中の亜鉛酸イオンの濃度が高くなり、（１）式の反応の進行が抑制されるので水素ガス発生量が減少し電池の保存時の耐漏液性を向上させることができる。このため電解液中に予め酸化亜鉛を飽和させておく方法が一般的に行われている。しかし、この方法では放電前の水素ガス発生の抑制は達成されるものの放電後のガス発生の抑制には効果がなく、また電解液に酸化亜鉛を溶解させることで電池の内部抵抗が大きくなり、放電性能が低下するという問題があった。
【０００６】
【発明が解決しようとする課題】
本発明は、上記の従来技術の課題を解決すべくなされたもので、水素ガス発生を大幅に抑制すると共に、重負荷における放電性能を向上させるアルカリマンガン電池用電解液、アルカリマンガン電池用亜鉛合金粉末およびその製造方法を提供することを目的とする．
【０００７】
【課題を解決するための手段】
本発明者等は上記目的を達成すべく鋭意研究の結果、水酸化カリウム中の亜鉛濃度を３重量％以下、好ましくは金属亜鉛、酸化亜鉛もしくは水酸化亜鉛を添加してその亜鉛濃度が１重量％から２．５重量％の範囲の水酸化カリウム溶液を電解液として用い、これに所定量の添加元素を合金成分として含有する亜鉛合金粉を合体させて負極材とすることにより、両者の相乗効果によって上記目的が達成されることを見いだし、本発明に到達した。
【０００８】
すなわち、本発明は第１に、精製した溶融亜鉛を０．００１〜０．０１重量％のＡｌ、０．００１〜０．０５重量％のＢｉおよび０．０１〜０．１重量％のＩｎで合金化した溶湯からアトマイズして得たアルカリ電池用亜鉛合金粉末を、酸化亜鉛添加量が３％以下の水酸化カリウム水溶液からなる電解液およびゲル化剤と撹拌混合して製造されたことを特徴とするゲル状アルカリマンガン電池用負極材；第２に、精製した溶融亜鉛を０．００１〜０．０１重量％のＡｌ、０．００１〜０．０５重量％のＢｉおよび０．０１〜０．１重量％のＩｎで合金化した溶湯からアトマイズして得たアルカリ電池用亜鉛合金粉末を、酸化亜鉛添加量が３％以下の水酸化カリウム水溶液からなる電解液およびゲル化剤と撹拌混合して製造され、放電後の水素ガス発生量が０．６０ｍｌ／（ＬＲ６・ｄａｙ）以下であることを特徴とするゲル状アルカリマンガン電池用負極材；第３に、精製した溶融亜鉛を０．００１〜０．０１重量％のＡｌ、０．００１〜０．０５重量％のＢｉおよび０．０１〜０．１重量％のＩｎで合金化した溶湯からアトマイズして得たアルカリ電池用亜鉛合金粉末を、酸化亜鉛無添加の水酸化カリウム水溶液からなる電解液およびゲル化剤と撹拌混合して製造されたことを特徴とするゲル状アルカリマンガン電池用負極材；第４に、精製した溶融亜鉛をＢｉ、ＩｎおよびＰｂで合金化した溶湯からアトマイズして得たアルカリ電池用亜鉛合金粉末を、酸化亜鉛添加量が３％以下の水酸化カリウム水溶液からなる電解液およびゲル化剤と撹拌混合して製造されたことを特徴とするゲル状アルカリマンガン電池用負極材；第５に、精製した溶融亜鉛を０．００１〜０．０５重量％のＢｉ、０．０１〜０．１重量％のＩｎおよび０．０１〜１．０重量％のＰｂで合金化した溶湯からアトマイズして得たアルカリ電池用亜鉛合金粉末を、酸化亜鉛添加量が３％以下の水酸化カリウム水溶液からなる電解液およびゲル化剤と撹拌混合して製造されたことを特徴とするゲル状アルカリマンガン電池用負極材；第６に、精製した溶融亜鉛を０．００１〜０．０５重量％のＢｉ、０．０１〜０．１重量％のＩｎおよび０．０１〜１．０重量％のＰｂで合金化した溶湯からアトマイズして得たアルカリ電池用亜鉛合金粉末を、酸化亜鉛添加量が３％以下の水酸化カリウム水溶液からなる電解液およびゲル化剤と撹拌混合して製造され、放電後の水素ガス発生量が０．７０ｍｌ／（ＬＲ６・ｄａｙ）以下であることを特徴とするゲル状アルカリマンガン電池用負極材；第７に、精製した溶融亜鉛を０．００１〜０．０５重量％のＢｉ、０．０１〜０．１重量％のＩｎおよび０．０１〜１．０重量％のＰｂで合金化した溶湯からアトマイズして得たアルカリ電池用亜鉛合金粉末を、酸化亜鉛無添加の水酸化カリウム水溶液からなる電解液およびゲル化剤と撹拌混合して製造されたことを特徴とするゲル状アルカリマンガン電池用負極材を提供するものである。
【０００９】
【作用】
本発明では電解液の原料として通常使用される工業用水酸化カリウムまたはその水溶液と酸化亜鉛とが使用でき、亜鉛合金粉末の原料としては通常使用される工業用精製亜鉛が使用できる。亜鉛合金粉末の製造は、この精製亜鉛を溶解し、Ａｌ、Ｂｉ、ＩｎおよびＰｂから選ばれる少なくとも１種以上の合金成分を添加して亜鉛合金とすることにより行う。
【００１０】
アルカリ電池用の電解液としては４０重量％程度（３８〜４２重量％）の水酸化カリウム水溶液の亜鉛濃度が３重量％以下であり、０．１〜２．５重量％含有されていることが好ましい。電解液中の亜鉛の濃度が３重量％を越えると放電の進行にともなって析出する酸化亜鉛量が多くなり、これがセパレータや亜鉛粒子表面に析出して、電池の内部抵抗を増大させるため放電寿命が短くなること、また亜鉛粒子表面では、後述するように酸化亜鉛と亜鉛との局部電池の形成により放電後の水素ガス発生量が著しく大きくなり、耐漏液性が低下するためである。
【００１１】
上記の電解液を用いて十分な効果を発揮させるためには亜鉛合金粉末中の添加金属を以下の様にすることが重要であり、従来の亜鉛合金粉末では電解液中の酸化亜鉛を減少させたものを使用しても、放電後のガス発生は抑制されるが、放電前の保存時の水素ガス発生量が大きい為に貯蔵性が著しく劣ることとなる。
【００１２】
また、上記亜鉛の添加金属のうちＡｌは亜鉛に合金化することにより、合金粉末粒子表面を平滑にし、反応性に関係する表面積を減少させ、ガス発生を抑制する効果があり、Ｂｉ、Ｉｎ、Ｐｂは合金粉末表面の水素過電圧を高めて電池として保存中の腐食によるガス発生を抑制する作用があり、これらの添加物は、Ａｌ０．００１〜０．１重量％、Ｂｉ０．００１〜０．０５重量％、Ｉｎ０．０１〜０．１重量％、Ｐｂ０．０１〜１．０重量％の成分範囲で含有するのが好ましく、これらの範囲を逸脱した場合は効果が小さいか十分な効果が得られないことがある。
【００１３】
従来、亜鉛のアルカリ溶液中における水素ガス発生を伴う腐食については亜鉛中に含まれる微量不純物元素、特にＦｅ、Ｎｉ、Ｃｏ、Ｓｂなどの水素過電圧の小さい元素による局部電池の生成が主たる原因と考えられていた。しかし、これらの元素を極限まで減らしてもなお水素ガス発生を伴う亜鉛の腐食が発生すること、さらに、亜鉛粉末を負極材としたアルカリ電池を過放電状態にした場合、放電前よりも数十倍高い水素ガス発生が生じる現象は上述の不純物の影響だけでは説明できなかった。そこで本発明者らは過放電後に発生する異常なガス発生量の原因を調べるために放電生成物である酸化亜鉛および電解液に予め溶解させる酸化亜鉛に着目し種々の試験を行った結果、この酸化亜鉛が水素ガス発生源になりうることを突き止め本発明に達した。以下にその試験結果の一例を示す。試験（１）は所定量の添加金属を溶解させた亜鉛合金溶湯からアトマイズ法により亜鉛合金粉末を作成し、この亜鉛合金粉末に酸化亜鉛粉末を配合し、４０重量％水酸化カリウム水溶液に浸漬しそのガス発生量について調べた。試験（２）は試験（１）と同様に亜鉛合金粉末を作成し、酸化亜鉛量の異なる電解液の濃度を使用し、電解液を所定量の水で希釈したものを用いて試験（１）と同様に水素ガス発生量について調べたものである。
【００１４】
【表１】

【００１５】
【表２】

【００１６】
試験（１）の結果より、酸化亜鉛粉末を混合した亜鉛合金粉末は著しい水素ガス発生量を示し、酸化亜鉛がガス発生源であることが分かる。試験（２）の結果より、酸化亜鉛溶解量の多い電解液を便用すると水で希釈した場合に水素ガス発生量の増加が大きいことが分かる。試験（２）の結果は電解液を水で希釈することで予め溶解させた酸化亜鉛が水酸化亜鉛として析出した量の違いによるものと思われ、水酸化亜鉛が亜鉛合金粉表面に析出することで水素ガス発生が生じたものと思われる。
【００１７】
ここで電解液に溶解させる酸化亜鉛量を低減し、さらに上記添加金属を使用した亜鉛合金粉末を組み合わせることで放電後のガス発生量が低減し、放電特性が向上する理由については今のところ明確ではないが以下の様に考えられる。すなわち、酸化亜鉛を飽和状態まであらかじめ溶解させた電解液を使用して電池に組み込み放電させた場合、電解液中の酸化亜鉛が飽和状態であっても電気化学的反応においては亜鉛が亜鉛酸イオンとなって溶解することが知られている。しかし、ある程度の溶解度以上では亜鉛酸イオンが溶解しきらずに酸化亜鉛もしくは水酸化亜鉛として析出することになる。これらは、セパレータや亜鉛粉の表面に析出することとなり、セパレータにこうした析出物が析出した場合、セパレータの目詰まりが起こり易くなること、亜鉛粒子表面に析出物が堆積することなどにより電解液中のイオンの移動が妨げられるため、電池の内部抵抗が大きくなり放電寿命が低下するものと考えられる。また、こうした反応で析出する酸化亜鉛や水酸化亜鉛は化学量論的欠陥によりＺｎ過剰型のｎ型半導体的性質を帯びるため導電性があり、また亜鉛と比較して貴な電位を有し、さらに水素過電圧も小さいことが知られている。したがって、酸化亜鉛や水酸化亜鉛が亜鉛表面に析出した場合、局部電池を形成し、自己放電により析出物上で水素ガスが発生し、亜鉛表面上では亜鉛の溶解もしくは亜鉛の酸化が生じることとなる。これが、過放電後のガス発生量が放電前より数十倍大きい値を示す理由と考えられる。さらに、水素過電圧の大きい元素を亜鉛合金粉末中に添加することで亜鉛合金粉末自体のガス発生量が抑制されるので電解液中の酸化亜鉛量を低減化することでこれらの相乗効果により放電後のガス発生が抑制されるものと考えられる。
以下、実施例および比較例により本発明をさらに説明するが、本発明はこれらに限定されるものではない
【００１８】
【実施例】
純度９９．９９５％以上の溶融した金属亜鉛に各添加元素を表１に示す含有量となるように添加して溶解し、この溶融物をアトマイズ法により粉体化して亜鉛合金粉末を作成した。電解液は水酸化カリウムを所定量水に溶解し、これに酸化亜鉛を所定量溶解したものを使用した。これらの亜鉛合金粉末、電解液をゲル化剤と混合してゲル状負極材とした後ＬＲ６型のセルに充填し、アルカリマンガン電池として組み込んだ。ゲル化剤としては、電池製造に通常使用されるポリアクリル酸ソーダおよびカルボキシメチルセルロース等を通常の添加量で使用することができる。本実施例ではポリアクリル酸ソーダを使用した。
水素ガス発生量は放電前と１０Ω、４８ｈの過放電を行った後のセルについて行い、放電前は６０℃、放電後は４５℃の温度での水素ガス発生量を調べた。結果を表３に示した。
放電性能は２０℃、１０Ω連続放電した場合の終止電圧０．７Ｖまでの持続時間を測定した。
【００１９】
【比較例】
実施例と同様に亜鉛合金粉末を作成し、電解液に酸化亜鉛を飽和状態まで溶解させたものを使用し、実施例と同様にアルカリマンガン電池を作成し、評価を行った。結果を表３に示した。
【００２０】
【表３】

表３の結果から分かるように、電解液中の酸化亜鉛添加量を３％以下とすることで、過放電後の水素ガス発生量が飽和状態と比較して１／３〜１／２まで抑制されることが分かる。また、放電性能も酸化亜鉛を飽和状態としたものと比して１０％程度向上することが分かる。
【００２１】
【発明の効果】
以上説明したように、本発明の方法によれば放電後の水素ガス発生量が大幅に抑制されるので、安全性が飛躍的に向上し、さらに放電性能も向上したアルカリマンガン電池を提供することができる。[0001]
[Industrial application fields]
The present invention relates to an electrolytic solution for an alkaline battery, a negative electrode material (negative electrode active material) for an alkaline battery, a zinc alloy powder that serves as a negative electrode material for an alkaline battery, and a method for producing the same.
[0002]
[Prior art]
Conventionally, zinc or zinc alloy powder has been used as a negative electrode material for batteries such as alkaline batteries. Zinc is preferred as a negative electrode material because of its high hydrogen overvoltage and relatively low price.
[0003]
As the electrolytic solution used for the negative electrode material, a solution in which about 40% by weight of potassium hydroxide is dissolved in water and zinc oxide is further dissolved in this electrolytic solution is generally used. In an aqueous solution of about 40% by weight potassium hydroxide, about 7% by weight zinc oxide is dissolved at room temperature. Here, the reason why zinc oxide is dissolved in the electrolytic solution to a saturated state is as follows.
[0004]
Since zinc is an amphoteric metal, a strong alkaline electrolyte such as a 40% by weight potassium hydroxide solution dissolves as zinc acid ions with the generation of hydrogen gas as shown in the following formulas (1) and (2). To do. When a gelled negative electrode material generating a large amount of hydrogen gas is incorporated into a battery, the generated hydrogen gas raises the internal pressure of the battery, pushes up the electrolyte in the battery, and the battery leaks during storage.
[0005]
Zn + 40H ⁻ → Zn (OH) ₄ ²⁻ + 2e ⁻ (1)
2H ₂ O + 2e ⁻ → H ₂ ↑ + 2OH ⁻ (2)
Therefore, if zinc oxide is saturated in advance in the electrolytic solution, the concentration of zincate ions in the electrolytic solution increases, and the progress of the reaction of formula (1) is suppressed, so the amount of hydrogen gas generated decreases and the battery The leakage resistance during storage can be improved. For this reason, a method of previously saturating zinc oxide in the electrolytic solution is generally performed. However, in this method, although suppression of hydrogen gas generation before discharge is achieved, there is no effect in suppressing gas generation after discharge, and the internal resistance of the battery increases by dissolving zinc oxide in the electrolyte, There was a problem that the discharge performance deteriorated.
[0006]
[Problems to be solved by the invention]
The present invention has been made to solve the above-mentioned problems of the prior art, and greatly suppresses the generation of hydrogen gas and improves the discharge performance under heavy loads, and an alkaline manganese battery electrolyte and an alkaline manganese battery zinc alloy The object is to provide a powder and a method for producing the same.
[0007]
[Means for Solving the Problems]
As a result of diligent research to achieve the above object, the present inventors have found that the zinc concentration in potassium hydroxide is 3% by weight or less, and preferably the zinc concentration is 1% by adding metal zinc, zinc oxide or zinc hydroxide. % Of potassium hydroxide solution in the range of 2.5 to 2.5% by weight as an electrolyte, and zinc alloy powder containing a predetermined amount of additive element as an alloy component is combined into a negative electrode material. The inventors have found that the above object can be achieved by the effect, and have reached the present invention.
[0008]
That is, the present invention firstly comprises purified molten zinc with 0.001 to 0.01% by weight of Al, 0.001 to 0.05% by weight of Bi and 0.01 to 0.1% by weight of In. The zinc alloy powder for an alkaline battery obtained by atomizing from the alloyed molten metal was manufactured by stirring and mixing with an electrolytic solution and a gelling agent composed of an aqueous potassium hydroxide solution containing 3% or less of zinc oxide. Secondly, a negative electrode material for a gel-like alkaline manganese battery; second, 0.001 to 0.01% by weight of Al, 0.001 to 0.05% by weight of Bi, and 0.01 to 0. A zinc alloy powder for an alkaline battery obtained by atomizing from a molten alloy alloyed with 1 wt% In is stirred and mixed with an electrolytic solution composed of a potassium hydroxide aqueous solution having a zinc oxide addition amount of 3% or less and a gelling agent. Manufactured and discharged hydrogen A negative electrode material for gel-like alkaline manganese battery, characterized in that the amount of generated gas is 0.60 ml / (LR6 · day) or less; Thirdly, 0.001 to 0.01% by weight of Al containing purified molten zinc A zinc alloy powder for an alkaline battery obtained by atomizing from a molten alloy alloyed with 0.001 to 0.05% by weight of Bi and 0.01 to 0.1% by weight of In A negative electrode material for a gel-like alkaline manganese battery produced by stirring and mixing with an electrolytic solution composed of an aqueous potassium solution and a gelling agent; fourth, alloyed purified molten zinc with Bi, In, and Pb It is characterized by being manufactured by stirring and mixing zinc alloy powder for alkaline batteries obtained by atomization from molten metal with an electrolytic solution and a gelling agent composed of an aqueous potassium hydroxide solution with a zinc oxide addition amount of 3% or less. Negative electrode material for gel alkaline manganese battery; Fifth, 0.001 to 0.05 wt% Bi, 0.01 to 0.1 wt% In and 0.01 to 1.0 wt% of purified molten zinc A zinc alloy powder for an alkaline battery obtained by atomizing from a molten alloy alloyed with Pb in an amount of 3% is manufactured by stirring and mixing with an electrolytic solution and a gelling agent composed of a potassium hydroxide aqueous solution with a zinc oxide addition amount of 3% or less. A negative electrode material for a gel-like alkaline manganese battery characterized by the following: Sixth, 0.001 to 0.05 wt% Bi, 0.01 to 0.1 wt% In and 0. A zinc alloy powder for an alkaline battery obtained by atomizing from a molten alloy alloyed with 01 to 1.0% by weight of Pb, an electrolyte solution and a gelling agent comprising a potassium hydroxide aqueous solution with a zinc oxide addition amount of 3% or less, Manufactured with stirring and mixing A negative electrode material for gelled alkaline manganese battery, characterized in that the amount of hydrogen gas generated after electricity is 0.70 ml / (LR6 · day) or less; Seventh, 0.001 to 0.05 of purified molten zinc A zinc alloy powder for an alkaline battery obtained by atomization from a molten alloy alloyed with Bi by weight, 0.01 to 0.1 wt% In and 0.01 to 1.0 wt% Pb is obtained without using zinc oxide. The present invention provides a negative electrode material for a gel-like alkaline manganese battery, which is manufactured by stirring and mixing with an electrolytic solution comprising an added aqueous potassium hydroxide solution and a gelling agent.
[0009]
[Action]
In the present invention, industrial potassium hydroxide or an aqueous solution thereof and zinc oxide which are usually used as a raw material for an electrolytic solution can be used, and industrially purified zinc which is usually used can be used as a raw material for a zinc alloy powder. The zinc alloy powder is produced by dissolving the purified zinc and adding at least one alloy component selected from Al, Bi, In and Pb to obtain a zinc alloy.
[0010]
As an electrolytic solution for an alkaline battery, the zinc concentration of a potassium hydroxide aqueous solution of about 40% by weight (38 to 42% by weight) is 3% by weight or less, and 0.1 to 2.5% by weight is contained. preferable. When the concentration of zinc in the electrolyte exceeds 3% by weight, the amount of zinc oxide deposited as the discharge progresses increases. This deposits on the surface of the separator and zinc particles, increasing the internal resistance of the battery, and thus the discharge life. This is because, on the surface of the zinc particles, as will be described later, the formation of a local battery of zinc oxide and zinc significantly increases the amount of hydrogen gas generated after discharge and decreases the leakage resistance.
[0011]
In order to exert a sufficient effect using the above electrolyte, it is important that the additive metal in the zinc alloy powder is as follows. With the conventional zinc alloy powder, the zinc oxide in the electrolyte is reduced. Even if it is used, the gas generation after the discharge is suppressed, but since the amount of hydrogen gas generated during storage before the discharge is large, the storage property is remarkably inferior.
[0012]
Also, among the zinc added metals, Al is alloyed with zinc, thereby smoothing the surface of the alloy powder particles, reducing the surface area related to the reactivity, and suppressing gas generation. Bi, In, Pb has the effect of increasing the hydrogen overvoltage on the surface of the alloy powder to suppress gas generation due to corrosion during storage as a battery. These additives include Al 0.001 to 0.1% by weight, Bi 0.001 to 0.05. It is preferable to contain it in the component range of wt%, In 0.01 to 0.1 wt%, and Pb 0.01 to 1.0 wt%, and if it deviates from these ranges, the effect is small or sufficient effect is obtained. There may not be.
[0013]
Conventionally, the corrosion that accompanies the generation of hydrogen gas in an alkaline solution of zinc is considered to be mainly caused by the generation of local batteries from trace impurity elements contained in zinc, particularly elements with low hydrogen overvoltage such as Fe, Ni, Co, and Sb. It was done. However, even if these elements are reduced to the limit, corrosion of zinc accompanied by the generation of hydrogen gas still occurs. The phenomenon that hydrogen gas generation is twice as high cannot be explained only by the influence of the above-mentioned impurities. Therefore, the present inventors conducted various tests focusing on zinc oxide, which is a discharge product, and zinc oxide previously dissolved in an electrolytic solution, in order to investigate the cause of abnormal gas generation generated after overdischarge. Ascertaining that zinc oxide can be a hydrogen gas generation source, the present invention has been achieved. An example of the test results is shown below. In test (1), a zinc alloy powder was prepared by an atomizing method from a molten zinc alloy in which a predetermined amount of additive metal was dissolved, and this zinc alloy powder was mixed with zinc oxide powder and immersed in a 40 wt% aqueous potassium hydroxide solution. The amount of gas generated was examined. Test (2) is similar to test (1), in which a zinc alloy powder is prepared, and the concentration of the electrolytic solution with a different amount of zinc oxide is used, and the electrolytic solution is diluted with a predetermined amount of water. Similarly, the amount of hydrogen gas generated was investigated.
[0014]
[Table 1]

[0015]
[Table 2]

[0016]
From the result of the test (1), it can be seen that the zinc alloy powder mixed with the zinc oxide powder shows a significant hydrogen gas generation amount, and that zinc oxide is the gas generation source. From the results of test (2), it can be seen that when an electrolytic solution having a large amount of zinc oxide dissolved is used, the increase in the amount of hydrogen gas generated is large when diluted with water. The result of test (2) seems to be due to the difference in the amount of zinc oxide that was previously dissolved by diluting the electrolyte with water and deposited as zinc hydroxide, and zinc hydroxide was deposited on the surface of the zinc alloy powder. It seems that hydrogen gas generation occurred.
[0017]
It is clear for now why the amount of zinc oxide dissolved in the electrolyte is reduced and the amount of gas generated after discharge is reduced by combining the zinc alloy powder using the above-mentioned added metals, resulting in improved discharge characteristics. However, it is considered as follows. That is, when an electrolytic solution in which zinc oxide is dissolved in advance to a saturated state is used and discharged in a battery, even if the zinc oxide in the electrolytic solution is in a saturated state, zinc is zincate ion in an electrochemical reaction. And is known to dissolve. However, when the solubility is higher than a certain level, zincate ions are not completely dissolved but are precipitated as zinc oxide or zinc hydroxide. These will be deposited on the surface of the separator and zinc powder, and when such a deposit is deposited on the separator, the separator is likely to be clogged, and the deposit is deposited on the surface of the zinc particles. It is considered that the internal resistance of the battery is increased and the discharge life is reduced. In addition, zinc oxide and zinc hydroxide precipitated by such a reaction have conductivity because they have a Zn-rich n-type semiconductor property due to stoichiometric defects, and have a noble potential compared to zinc, Further, it is known that the hydrogen overvoltage is small. Therefore, when zinc oxide or zinc hydroxide is deposited on the zinc surface, a local battery is formed, hydrogen gas is generated on the deposit by self-discharge, and zinc is dissolved or oxidized on the zinc surface. Become. This is considered to be the reason why the amount of gas generated after overdischarge shows a value several tens of times greater than that before discharge. Furthermore, by adding an element with a large hydrogen overvoltage to the zinc alloy powder, the amount of gas generated in the zinc alloy powder itself is suppressed. It is thought that the generation of gas is suppressed.
Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
【Example】
Each additive element was added and dissolved in molten metal zinc having a purity of 99.995% or more so as to have the content shown in Table 1, and the melt was pulverized by an atomizing method to prepare a zinc alloy powder. As the electrolytic solution, potassium hydroxide was dissolved in a predetermined amount of water, and zinc oxide was dissolved therein in a predetermined amount. These zinc alloy powders and electrolytes were mixed with a gelling agent to form a gelled negative electrode material, which was then filled into an LR6 type cell and incorporated as an alkaline manganese battery. As the gelling agent, sodium polyacrylate, carboxymethyl cellulose and the like which are usually used for battery production can be used in a normal addition amount. In this embodiment, sodium polyacrylate was used.
The amount of hydrogen gas generated was measured before the discharge and after the cell was overdischarged for 10Ω for 48 hours. The amount of hydrogen gas generated at a temperature of 60 ° C. before the discharge and 45 ° C. after the discharge was examined. The results are shown in Table 3.
The discharge performance was measured by measuring the duration up to a final voltage of 0.7 V when 10 Ω was continuously discharged at 20 ° C.
[0019]
[Comparative example]
A zinc alloy powder was prepared in the same manner as in the example, and an alkaline manganese battery was prepared and evaluated in the same manner as in the example using a solution in which zinc oxide was dissolved in a saturated state. The results are shown in Table 3.
[0020]
[Table 3]

As can be seen from the results in Table 3, the amount of hydrogen gas generated after overdischarge is suppressed to 1/3 to 1/2 compared to the saturated state by setting the amount of zinc oxide added in the electrolyte to 3% or less. You can see that Moreover, it turns out that discharge performance improves also about 10% compared with what made the zinc oxide saturated.
[0021]
【The invention's effect】
As described above, according to the method of the present invention, the amount of hydrogen gas generated after discharge is greatly suppressed, and therefore, an alkaline manganese battery with greatly improved safety and further improved discharge performance is provided. Can do.

Claims

A refined molten zinc is obtained by atomizing from a molten alloy alloyed with 0.001-0.01 wt% Al, 0.001-0.05 wt% Bi and 0.01-0.1 wt% In. A negative electrode for a gel-like alkaline manganese battery produced by stirring and mixing a zinc alloy powder for an alkaline battery with an electrolytic solution and a gelling agent comprising a potassium hydroxide aqueous solution containing 3% or less of zinc oxide. Wood.

A refined molten zinc is obtained by atomizing from a molten alloy alloyed with 0.001-0.01 wt% Al, 0.001-0.05 wt% Bi and 0.01-0.1 wt% In. The zinc alloy powder for alkaline batteries was produced by stirring and mixing with an electrolyte solution and a gelling agent composed of an aqueous potassium hydroxide solution with a zinc oxide addition amount of 3% or less, and the hydrogen gas generation amount after discharge was 0.60 ml / (LR6 · day) or less, A negative electrode material for a gel-like alkaline manganese battery.

A refined molten zinc is obtained by atomizing from a molten alloy alloyed with 0.001-0.01 wt% Al, 0.001-0.05 wt% Bi and 0.01-0.1 wt% In. A negative electrode material for a gel-like alkaline manganese battery produced by stirring and mixing the zinc alloy powder for an alkaline battery with an electrolytic solution composed of an aqueous potassium hydroxide solution containing no zinc oxide and a gelling agent.

An electrolytic solution and a gelling agent comprising a zinc alloy powder for an alkaline battery obtained by atomizing purified molten zinc from a molten alloy obtained by alloying with Bi, In and Pb, and an aqueous potassium hydroxide solution containing 3% or less of zinc oxide. A negative electrode material for a gel-like alkaline manganese battery produced by mixing with stirring.

Obtained by atomizing purified molten zinc from a molten alloy alloyed with 0.001 to 0.05 wt% Bi, 0.01 to 0.1 wt% In and 0.01 to 1.0 wt% Pb. A negative electrode for a gel-like alkaline manganese battery produced by stirring and mixing a zinc alloy powder for an alkaline battery with an electrolyte and a gelling agent composed of a potassium hydroxide aqueous solution containing 3% or less of zinc oxide Wood.

Obtained by atomizing purified molten zinc from a molten alloy alloyed with 0.001 to 0.05 wt% Bi, 0.01 to 0.1 wt% In and 0.01 to 1.0 wt% Pb. The zinc alloy powder for alkaline batteries was produced by stirring and mixing with an electrolyte solution and a gelling agent composed of a potassium hydroxide aqueous solution with a zinc oxide addition amount of 3% or less, and the hydrogen gas generation amount after discharge was 0.70 ml / (LR6 · day) or less, A negative electrode material for a gel-like alkaline manganese battery.

Obtained by atomizing purified molten zinc from a molten alloy alloyed with 0.001 to 0.05 wt% Bi, 0.01 to 0.1 wt% In and 0.01 to 1.0 wt% Pb. A negative electrode material for a gel-like alkaline manganese battery produced by stirring and mixing the zinc alloy powder for an alkaline battery with an electrolytic solution composed of an aqueous potassium hydroxide solution containing no zinc oxide and a gelling agent.