JPH0348618B2

JPH0348618B2 -

Info

Publication number: JPH0348618B2
Application number: JP59104674A
Authority: JP
Inventors: Akira Hayashi; Kazumasa Yoshida
Original assignee: Toshiba Battery Co Ltd
Current assignee: FDK Twicell Co Ltd
Priority date: 1984-05-25
Filing date: 1984-05-25
Publication date: 1991-07-25
Also published as: JPS6110859A

Description

[Detailed description of the invention]

［発明の技術分野］本発明は、アルカリ金属の水酸化物を主電解質
とするアルカリ電解液中において、低汞化率また
は無汞化で使用する亜鉛負極に関するものであ
る。［発明の技術的背景］一般にアルカリ電池用負極材料である亜鉛粉末
ないし亜鉛合金粉末は色々な方法でつくることが
できるが、最も広く用いられているのは4N（純度
99.99％）以上の高純度電気亜鉛を用い、アト
マイズ法で噴霧して得た不規則形状の粒子群から
なる亜鉛粉末であつて、粒径（短径）60μｍない
し350μｍ程度、形状指数2.0ないし2.3程度、酸化
亜鉛含有率0.2重量％ないし0.3重量％程度のもの
である。［背景技術の問題点］このような亜鉛粉末はアルカリ電解液中での水
素過電圧が低く、また実際上電解液量の極度に限
定されている電池内で放電された場合の化学分極
も比較的大きいことから、電池の種類・構造や使
用目的に応じて種々な程度に汞化
（amalgamation）して用いるのが普通である。
この場合の汞化率は、汞化亜鉛粉末バルクの重量
比として５重量％ないし25重量％の範囲にある
が、特に６重量％ないし12重量％程度のものが多
用されている。また、酸化亜鉛含有率は0.4重量
％ないし0.9重量％程度のものが多い。負極中における多量の水銀の存在は、必然的に
設計上電池内で負極が占めるべく定められた容積
内における活物質量の減少をまねき電池容量の低
下を伴なうから好ましくない。のみならず周知の
ように水銀は公害規制物質であり、その使用量の
低減は近年特に強い社会的要請となつている。負
極亜鉛中の水銀添加量を低減するための研究は広
く行なわれてきており、その手段は主に化学的な
方法によるものが多く、例えば亜鉛合金組成、亜
鉛粒子の表面処理、アルカリ電解液への腐蝕抑制
剤（Inhibitor）の添加等に関するものである。このような目的の試みは研究的にはある程度の
水準のものが得られつつあるが、亜鉛または亜鉛
合金を粉末化し無汞化の状態で、あるいは少なく
とも従来に比して低い汞化率で使用したときに従
来の高い汞化率の汞化亜鉛粉末に匹敵する程度の
水素ガス発生抑制効果は得られておらず、商用ア
ルカリ電池の負極活物質として実用化されるに至
つていない。［発明の目的］本発明の目的はアルカリ電池の負極に使用する
亜鉛粉末または亜鉛合金粉末の主として物理的性
状の改良を行うことによつて、従来技術のものに
比して低汞化ないし無汞化の状態で使用しても現
用されている高い汞化率の汞化亜鉛粉末に匹敵す
る程度に電池内での水素ガス発生が少なく、従つ
て貯蔵特性のよいアルカリ・亜鉛電池を提供する
ことである。［発明の概要］即ち本発明では不可避的混入元素、特に鉄含有
率の可及的少ない高純度亜鉛または亜鉛に少量添
加して合金化せしめることにより、アルカリ電解
液中で防蝕効果をもたらし、且つ分極特性を阻害
することのない金属性元素を添加した亜鉛合金を
用い、且つ該亜鉛または亜鉛合金を実用上の所定
粒度ないし平均粒径となるよう粒状化するに際し
て、従来品に比較してカサ比重を著しく大きくす
るようにした噴霧亜鉛合金粉末をアルカリ電池の
負極活物質として使用することによつて、従来品
に比して低い汞化率ないし無汞化で使用した場合
にも電池内における水素ガス発生を実用上充分な
程度にまで抑制できるようにしたものである。［発明の実施例］以下実施例を用いて本発明の詳細を説明する。
第１表に本発明による噴霧亜鉛合金粉末と従来技
術による噴霧亜鉛合金粉末とのアルカリ電解液中
における水素ガス発生速度、カサ比重、平均形状
指数及び酸化亜鉛含有率の比較を示した。第１表
において水素ガス発生速度は、酸化亜鉛を飽和し
た35％KOH溶液10ml中に10ｇの被験試料を浸漬
し、数torrの減圧下で30分間脱気したのち、電解
液面を流動パラフインで充し、60℃で174時間放
置したときのものである。また平均形状指数は、
各粒子の最大方向の長さをｌ（長径）、ｌ軸と直角
方向の最も大きい長さをＳ（短径）としたとき
ｌ／Ｓは、即ちその粒子の変形度を細長さで現わ
した形状指数である。実用されているアトマイズ
亜鉛粉末はさまざまな形状のものを含んでおり、
これら粒子の変形度を示すのに平均形状指数を用
いるのが最も簡明且つ実用的である。一般に多用
される噴霧亜鉛粒子の形状指数は大部分が1.8な
いし3.6程度のものであり、その平均的形状指数
は2.0ないし2.3程度である。ある粉末を標準篩と
振盪機を用いて分級して示される粒度ないし粒度
分布とは、その分級条件が妥当であれば略々上述
した短径ｓの粒径ないし粒径分布を示すものであ
る。 [Technical Field of the Invention] The present invention relates to a zinc negative electrode that is used at a low or zero rate in an alkaline electrolyte containing an alkali metal hydroxide as the main electrolyte. [Technical background of the invention] Zinc powder or zinc alloy powder, which is generally a negative electrode material for alkaline batteries, can be produced by various methods, but the most widely used is 4N (purity
Zinc powder consisting of a group of irregularly shaped particles obtained by atomizing using high-purity electrolytic zinc (99.99%) or higher, with a particle diameter (minor axis) of about 60 μm to 350 μm, and a shape index of 2.0 to 2.3. The zinc oxide content is about 0.2% to 0.3% by weight. [Problems in the background art] Such zinc powder has a low hydrogen overvoltage in an alkaline electrolyte, and also has a relatively low chemical polarization when discharged in a battery where the amount of electrolyte is actually extremely limited. Because of their large size, they are usually amalgamated to various degrees depending on the type, structure, and intended use of the battery.
In this case, the filtration rate is in the range of 5% to 25% by weight as a weight ratio of the bulk zinc filtrate powder, and in particular, a ratio of 6% to 12% by weight is often used. Further, the zinc oxide content is often about 0.4% by weight to 0.9% by weight. The presence of a large amount of mercury in the negative electrode is undesirable because it inevitably leads to a decrease in the amount of active material within the volume that the negative electrode is designed to occupy within the battery, resulting in a decrease in battery capacity. Furthermore, as is well known, mercury is a pollution control substance, and reducing its usage has become a particularly strong social demand in recent years. Research has been widely conducted to reduce the amount of mercury added in negative electrode zinc, and the methods for doing so are mainly chemical methods, such as zinc alloy composition, surface treatment of zinc particles, and changes in alkaline electrolyte. This concerns the addition of corrosion inhibitors. Attempts for this purpose have been achieved to a certain degree in research, but zinc or zinc alloys are powdered and used in a non-oxidized state, or at least at a lower percentage of oxidation than in the past. However, it has not been able to achieve a hydrogen gas generation suppressing effect comparable to that of conventional zinc oxide powder with a high oxidation rate, and has not yet been put to practical use as a negative electrode active material for commercial alkaline batteries. [Objective of the Invention] The object of the present invention is to improve the physical properties of the zinc powder or zinc alloy powder used in the negative electrode of alkaline batteries, thereby reducing or eliminating the zinc powder compared to those of the prior art. To provide an alkaline-zinc battery which generates less hydrogen gas within the battery and has good storage characteristics, even when used in a filtrated state, to the extent that it is comparable to the currently used zinc powder with a high filtration rate. That's true. [Summary of the invention] That is, in the present invention, by adding a small amount to unavoidable mixed elements, especially high-purity zinc or zinc with the lowest possible iron content and alloying it, a corrosion-preventing effect is brought about in an alkaline electrolyte, and When using a zinc alloy to which metallic elements are added that do not inhibit polarization characteristics, and when granulating the zinc or zinc alloy to a practical predetermined particle size or average particle size, it is bulkier than conventional products. By using atomized zinc alloy powder with a significantly increased specific gravity as the negative electrode active material of alkaline batteries, it is possible to improve This makes it possible to suppress hydrogen gas generation to a practically sufficient level. [Examples of the Invention] The details of the present invention will be explained below using Examples.
Table 1 shows a comparison of the hydrogen gas generation rate, bulk specific gravity, average shape index, and zinc oxide content in an alkaline electrolyte between the sprayed zinc alloy powder according to the present invention and the sprayed zinc alloy powder according to the prior art. In Table 1, the hydrogen gas generation rate is determined by immersing 10 g of the test sample in 10 ml of a 35% KOH solution saturated with zinc oxide, degassing it for 30 minutes under a reduced pressure of several torr, and then cleaning the electrolyte surface with liquid paraffin. This is when the sample was filled and left at 60℃ for 174 hours. Also, the average shape index is
When the length of each particle in the maximum direction is l (major axis), and the maximum length in the direction perpendicular to the l axis is S (minor axis), l/S represents the degree of deformation of the particle in terms of slenderness. This is the shape index. Atomized zinc powder in practical use includes various shapes.
It is simplest and most practical to use the average shape index to indicate the degree of deformation of these particles. The shape index of commonly used atomized zinc particles is mostly about 1.8 to 3.6, and the average shape index is about 2.0 to 2.3. The particle size or particle size distribution shown by classifying a certain powder using a standard sieve and a shaker is approximately the particle size or particle size distribution of the short diameter s described above, if the classification conditions are appropriate. .

【表】第１表中Ｄ、Ｅは本発明の実施例、Ａは従来
例、Ｂ、Ｃは比較例である。即ち第１表中Ａは代
表的従来品であつて、純度4Nの電気亜鉛を大気
中でアトマイズ法により粒状化したのち、100μ
ｍないし300μｍの範囲に分級し、稀NaOH溶液
中で金属水銀と汞化せしめて得た汞化率6.5重量
％の汞化亜鉛粉末である。このものの汞化前（未
汞化）のカサ比重は普通2.5ｇ・cm^-3ないし2.8
ｇ・cm^-3程度のものである。次に第１表中Ｂは比較品であつて同様に純度
4Nの電気亜鉛を大気中でアトマイズ法により粒
状化し、分級後、所要量の塩化第二水銀を含む稀
CH₃COOH溶液中で処理し、汞化せしめて得た
汞化率2.81重量％の低汞化亜鉛合金粉末である。
第１表中Ｃも比較品であつて鉛0.15重量％、ガリ
ウム0.13重量％を含む亜鉛合金を大気中でアトマ
イズ法で粒状化したのち、100μｍないし300μｍ
の範囲に分級して得た無汞化亜鉛合金粉末であ
る。第１表中ＤないしＥは、それぞれ本発明の一実
施例であつて、Ｄは前記Ｂと同様純度4Nの電気
亜鉛を窒素雰囲気中でアトマイズ法により粒状化
したのち分級して粒径100μｍないし300μｍとし、
次に所要量の塩化二水銀を含む稀CH₃COOH溶
液中で処理して得た汞化率2.85重量％の低汞化亜
鉛合金粉末である。またＥは前記Ｃと同一組成の
Zn−Pb−Ga三元合金を窒素ガス雰囲気中でアト
マイズ法により粒状化したのち分級して粒径
100μｍないし300μｍの範囲とした無汞化亜鉛合
金粉末である。第１表Ｄ、Ｅで示した本発明のカサ比重を大き
くするようにした亜鉛合金粉末の場合には、2.85
重量％の低汞化率ないし無汞化で用いてもカサ比
重の小さいＢ、Ｃに比べ水素ガス発生速度が著し
く減少していることがわかる。また、Ｅはこれを
１ないし３重量％低汞化率に汞化することによつ
て、水素ガス発生速度を更に小さくすることがで
きる。本発明におけるカサ比重の大きい亜鉛合金粒が
略々同一粒度においてアルカリ電解液中で水素ガ
ス発生の少ない理由については、充分解明できて
いない。しかしながらSEMによれば図面に示し
たような粒子形状の差が観察される。第１図に本
発明による噴霧亜鉛合金粉末の粒子形状モデルを
示し、第２図には従来粉末の粒子形状モデルを示
した。各図ともａは粒径の大きいもの、ｂは短径
の小さいものの形状モデルである。第１図に示し
た本発明の亜鉛合金粒では、第２図に示した従来
品に比して粒子形状に鋭角的な部分が著しく少な
く粒子端部が全体に丸味を帯びており、粒子表面
にもシワ状模様の形成がほとんどみられない。また、粒径の小さい粒子ほど従来品に比して一
層球体に近く、形状指数1.0に近いものが多く混
在している。またこの形状変化に対応して平均粒
状指数も従来の2.0ないし2.3程度に対し、本発明
の場合は1.6〜1.0となつている。これらの形状変
化はカサ比重を大きくしている主因と考えられる
が、同時に粒子間の摩擦を少なくしブリツジも形
成し難いため粉体流動性（flow rate）も改良さ
れていることが認められている。また、第１表に示したようにカサ比重の大きい
亜鉛合金粉末では酸化亜鉛含有率が著しく小さ
い。酸化亜鉛含有率は過大でなければ水素ガス発
生速度にそれほど影響しないが、水素ガス発生量
のバラツキを生じやすく、特にアルカリ電池に実
用する場合苛酷な使用条件下の特性、例えば低温
における急放電特性やパルス放電特性を低下させ
ることがある。また、酸化亜鉛は電池の反応生成物であり、そ
の過度の含有は活物質量の減少を意味するから、
その含有率は可及的に小さいことが望ましい。［発明の効果］以上の観察から本発明の効果について次の如く
考察される。すなわち過度現象的にみると従来に
おける場合は、ノズルから圧出された溶融亜鉛な
いし溶融亜鉛合金がエアー・ブローによつて噴霧
化された直後の清浄な液滴状金属粒子表面に急速
に単分子層またそれ以上の厚さの酸化膜が生成さ
れる。酸化膜の生成は液状金属粒子の界面張力を
変化させ、個々の粒子形状が界面張力による凝集
の影響を充分うけないうちに融点以下にまで冷却
固化してしまうため、粒子の大きさに応じ噴霧時
の加速度・方向や重力等によつて支配されるさま
ざまな不規則形状の粒子を生じ、且つ粒子端部に
鋭角的部分が形成され易いのである。また金属粒
子表面のシワ状模様の形成は、表面に酸化膜の生
成した液状金属粒子が冷却固化するまでの運動の
過程で刻々形状変化をし、その都度表面の硬化膜
が破れて新鮮な金属面が露出し、その部分が再酸
化するということの繰返しによつて生成されたも
のと考えられる。これに対して本発明の実施例１で示した場合に
は、ノズルから圧出された溶融亜鉛または溶融亜
鉛合金が高圧窒素ガスで不活性ガス雰囲気中へ噴
霧され、粒状化されたときに液状合金粒子表面が
ほとんどまたは全く酸化を受けないので、界面張
力による凝集、球状化の作用を受け易く、また粒
子が融点以下に冷却固化するまでの間に加速度や
重力の影響を受けることの小さい微粒子ほど球状
化し易いものと考えられる。半径の大きい粒子では重力等の影響により粒子
形状全体としては球状化し難く不規則形状になり
易いけれども、局部的には粒子の端部が丸味を帯
び鋭角的な部分が減少するので形状指数は小とな
る。また粒子表面は酸化膜の影響を受けないので
比較的平滑面となる。これらの結果から平均形状
指数が小さくなり、粒子間の摩擦が減少して流動
性をよくし、カサ比重を大きくしているものと思
われる。またこれらの変化が合金結晶や結晶粒界
の状態および粒界への不可避的含有不純元素や有
効添加元素の偏析挙動に何らかの変化をもたら
し、結果的に本発明による噴霧亜鉛合金粉末の水
素過電圧を大きくしているものと思われる。いず
れにしてもこのような好ましい特性上の変化は、
カサ比重の変化と相関対応していることによつ
て、カサ比重によつて一括管理することが可能で
あることがわかつた。以上のごとく本発明は高純度亜鉛または亜鉛に
少量添加して合金化せしめることによりアルカリ
電解液中で防蝕効果をもたらし、且つ分極特性を
阻害することのない金属性元素を添加した亜鉛合
金を用い、且つ該亜鉛または亜鉛合金を実用上の
所定粒度ないし平均粒径となるよう粒状化するに
際して、従来品に比してカサ比重を著しく大きく
するようにした亜鉛粉末ないし亜鉛合金粉末をア
ルカリ電池の負極活物質として使用することによ
つて、従来の比して低い汞化率ないし無汞化で使
用した場合にも電池内における水素ガス発生を相
当程度抑制できるようにしたものである。また、
このようにカサ密度の大きい粉末を用いることに
よつて同一負極容積における活動質量を増大せし
め、低温における急放電特性を向上できると共
に、電池の製造工程においても、取扱作業性がよ
く容積計量時における電池内充填重量のバラツキ
の少ないゲル状亜鉛負極を得ることができる等、
その工業的効果の大きいものである。本発明による低汞化ないし無汞化の亜鉛合金粉
末はアルカリ電解液及び任意のゲル化剤と混合し
たゲル状亜鉛を負極に用いるいわゆるゲル方式及
び亜鉛合金粒子表面にあらかじめ主としてゲル化
剤からなる薄層を形成せしめておき、これを負極
容器内でアルカリ電解液の注入によりゲル化させ
るいわゆるPowder with Gel方式の何れにも適
用できる。また本発明の技術は過酸化銀電池、酸化銀電
池、ニツケル・亜鉛電池、アルカリ・マンガン電
池、空気・亜鉛電池等亜鉛を負極活物質とする各
種構造（円筒型、ボタン型、コイン型、超扁平型
等）のアルカリ電池に適用して効果を発揮するも
のである。[Table] In Table 1, D and E are examples of the present invention, A is a conventional example, and B and C are comparative examples. That is, A in Table 1 is a typical conventional product, in which electrolytic zinc with a purity of 4N is granulated by the atomization method in the air, and then 100μ
This is a zinc hydride powder with a filtration rate of 6.5% by weight, which is obtained by classifying the powder into particles in the range of 300 μm to 300 μm and filtrating it with metal mercury in a dilute NaOH solution. The bulk specific gravity of this product before it becomes oxidized (not oxidized) is usually 2.5 g cm ^-3 to 2.8.
It is about g cm ^-3 . Next, B in Table 1 is a comparative product and has the same purity.
4N electrolytic zinc is granulated by the atomization method in the air, and after classification, a rare powder containing the required amount of mercuric chloride is
This is a low viscosity zinc alloy powder with a viscosity of 2.81% by weight, obtained by treatment in a CH ₃ COOH solution and viscosity.
C in Table 1 is also a comparative product, in which a zinc alloy containing 0.15% by weight of lead and 0.13% by weight of gallium is granulated by the atomization method in the air, and the size is 100 μm to 300 μm.
This is a non-oxidized zinc alloy powder obtained by classifying into the following range. D to E in Table 1 are each an example of the present invention, and D is similar to B above, in which electrolytic zinc with a purity of 4N is granulated by the atomization method in a nitrogen atmosphere, and then classified to have a particle size of 100 μm or more. 300μm,
Next, the powder was treated in a dilute CH ₃ COOH solution containing the required amount of dimercury chloride to obtain a low filtration zinc alloy powder with a filtration rate of 2.85% by weight. Also, E has the same composition as C above.
The Zn-Pb-Ga ternary alloy is granulated by the atomization method in a nitrogen gas atmosphere and then classified to determine the particle size.
It is a non-viscous zinc alloy powder with a particle size in the range of 100 μm to 300 μm. In the case of the zinc alloy powder of the present invention shown in Table 1 D and E, which has a large bulk specific gravity, 2.85
It can be seen that the rate of hydrogen gas generation is significantly reduced compared to B and C, which have a small bulk specific gravity, even when used at a low or no viscosity rate by weight. In addition, by reducing E to a 1 to 3% by weight reduction rate, the rate of hydrogen gas generation can be further reduced. The reason why the zinc alloy particles having a large bulk specific gravity in the present invention generate less hydrogen gas in an alkaline electrolyte when the particle size is substantially the same has not been fully elucidated. However, according to SEM, differences in particle shape as shown in the drawings are observed. FIG. 1 shows a particle shape model of the atomized zinc alloy powder according to the present invention, and FIG. 2 shows a particle shape model of the conventional powder. In each figure, a is a shape model of a particle with a large diameter, and b is a shape model of a particle with a small breadth. The zinc alloy grains of the present invention shown in Fig. 1 have significantly fewer sharp angles in the particle shape than the conventional product shown in Fig. 2, and the particle ends are rounded as a whole, and the particle surface There is hardly any wrinkle-like pattern formation on the surface. In addition, the smaller the particle size, the more spherical it is compared to the conventional product, and there are many particles with a shape index close to 1.0. Corresponding to this change in shape, the average graininess index is also 1.6 to 1.0 in the case of the present invention, compared to about 2.0 to 2.3 in the conventional case. These changes in shape are thought to be the main reason for increasing the bulk specific gravity, but at the same time, it has been recognized that the powder fluidity (flow rate) is also improved because it reduces the friction between particles and makes it difficult to form bridges. There is. Furthermore, as shown in Table 1, zinc alloy powders with large bulk specific gravity have a significantly low zinc oxide content. The zinc oxide content does not significantly affect the hydrogen gas generation rate if it is not excessive, but it tends to cause variations in the amount of hydrogen gas generated, and especially when used in alkaline batteries, the characteristics under harsh usage conditions, such as rapid discharge characteristics at low temperatures. This may deteriorate the pulse discharge characteristics. In addition, zinc oxide is a reaction product of batteries, and excessive inclusion means a decrease in the amount of active material.
It is desirable that the content thereof be as small as possible. [Effects of the Invention] From the above observations, the effects of the present invention can be considered as follows. In other words, from a transient phenomenon point of view, in the conventional case, molten zinc or molten zinc alloy extruded from a nozzle rapidly forms single molecules on the surface of clean droplet-shaped metal particles immediately after being atomized by air blow. An oxide film with a thickness of 1 to 30 mm or more is produced. The formation of an oxide film changes the interfacial tension of the liquid metal particles, and the individual particle shapes cool and solidify below the melting point before they are sufficiently affected by agglomeration due to the interfacial tension. Particles with various irregular shapes are produced depending on the acceleration, direction, gravity, etc., and sharp edges are likely to be formed at the ends of the particles. In addition, the formation of wrinkle-like patterns on the surface of metal particles occurs because the liquid metal particles with an oxide film formed on their surfaces change shape every moment as they move until they cool and solidify. It is thought that it was produced by repeatedly exposing a surface and reoxidizing that part. On the other hand, in the case shown in Example 1 of the present invention, molten zinc or molten zinc alloy pressed out from a nozzle is sprayed into an inert gas atmosphere with high-pressure nitrogen gas, and when granulated, it becomes a liquid. Because the surface of the alloy particles undergoes little or no oxidation, they are susceptible to agglomeration and spheroidization due to interfacial tension, and are small particles that are not affected by acceleration or gravity until they are cooled below their melting point and solidified. It is thought that the more spherical the material, the easier it is to become spherical. For particles with a large radius, the shape of the particle as a whole is difficult to become spherical and tends to become irregular due to the influence of gravity, etc., but locally the edges of the particle become rounded and the sharp edges are reduced, so the shape index is small. becomes. Furthermore, the particle surface is not affected by the oxide film, so it becomes a relatively smooth surface. From these results, it seems that the average shape index becomes smaller, the friction between particles decreases, improving fluidity and increasing the bulk specific gravity. In addition, these changes bring about some changes in the state of alloy crystals and grain boundaries, as well as in the segregation behavior of unavoidably contained impurity elements and effective additive elements in grain boundaries, and as a result, the hydrogen overvoltage of the sprayed zinc alloy powder according to the present invention increases. It seems that it is getting bigger. In any case, such favorable changes in characteristics are
It was found that by correlating with changes in the specific gravity of the umbrella, it is possible to manage it collectively based on the specific gravity of the umbrella. As described above, the present invention uses high-purity zinc or a zinc alloy to which a metallic element is added that provides a corrosion-proofing effect in an alkaline electrolyte by adding a small amount to zinc and alloying it, and does not impede the polarization characteristics. In addition, when granulating the zinc or zinc alloy to a practical predetermined particle size or average particle size, zinc powder or zinc alloy powder with a bulk specific gravity significantly larger than that of conventional products is used for alkaline batteries. By using it as a negative electrode active material, hydrogen gas generation within the battery can be suppressed to a considerable extent even when used at a lower rate of oxidation or no oxidation compared to conventional ones. Also,
By using a powder with a large bulk density, the active mass in the same negative electrode volume can be increased, and rapid discharge characteristics at low temperatures can be improved. It is possible to obtain a gel-like zinc negative electrode with less variation in the filling weight inside the battery, etc.
It has great industrial effects. The zinc alloy powder of the present invention which has low or no gradient has a so-called gel method in which a gelled zinc mixed with an alkaline electrolyte and an arbitrary gelling agent is used as a negative electrode, and a gelling agent is mainly provided on the surface of the zinc alloy particles. It can be applied to any of the so-called Powder with Gel methods, in which a thin layer is formed and then gelled by injecting an alkaline electrolyte into the negative electrode container. The technology of the present invention also applies to various structures (cylindrical, button-shaped, coin-shaped, super It is effective when applied to alkaline batteries (flat type, etc.).

[Brief explanation of drawings]

第１図は本発明の噴霧亜鉛粉末を構成する粒子
の粒子形状モデルであり、第２図は従来の噴霧亜
鉛合金粉末を構成する粒子の粒子形状モデルであ
る。各図ともａは粒径の大きいもの、ｂは粒径の
小さいものの粒子形状を示す。 FIG. 1 is a particle shape model of particles constituting the atomized zinc powder of the present invention, and FIG. 2 is a particle shape model of particles constituting the conventional atomized zinc alloy powder. In each figure, a indicates the particle shape of a large particle, and b indicates a particle shape of a small particle.

Claims

[Claims] 1. In an alkaline battery using a zinc alloy powder having a mercury conversion rate of 3% by weight or less and a particle size of 100 to 300 μm as a negative electrode active material, the zinc alloy powder has a zinc oxide content. 0.1% by weight
or less, and the bulk specific gravity is 3.5 gcm ^-3 or more,
An alkaline zinc battery characterized by having an average shape index (major axis/minor axis) of 1.6 to 1.0.