MANGANESE DRY BATTERY AND MANGANESE DRY BATTERY MANUFACTURING METHOD

Abstract

An added element other than zinc is yielded at the grain boundaries of zinc forming a negative electrode zinc can. The added element includes at least one element selected from the group of Pb, Bi, Ca, Mg, Si, Al, and In. The zinc can is formed in such a manner that: melted zinc containing the added element is quenched at a quenching rate of 75 to 100° C./second for casting into a zinc plate; and the thus cast plate is subjected to impact molding at a temperature in the range between 20 and 30° C.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a manganese dry battery including a negative electrode zinc can excellent in corrosion resistance and a negative electrode zinc can used therein.

2. Description of Related Art

Negative electrode zinc cans used in manganese dry batteries involve lowering of battery capacity and degradation of discharge characteristics which are caused due to self discharge. To tackle these problems, addition of lead to zinc has been tried to improve the corrosion resistance of the zinc cans.

In view of environmental pollution, other approaches without using lead for improving the corrosion resistance of the zinc cans have been examined.

In Patent Document 1 (Japanese Patent Application laid open unexamined Publication No. 61-224265, Patent Document 2 (Japanese Patent Application laid open unexamined Publication No. 6-325771, and Patent Document 3 (Japanese Patent Application laid open unexamined Publication No. 2006-59546), there is disclosure that corrosion of a zinc can is prevented by forming an indium layer or a bismuth layer on the surface of the zinc can. This method utilizes the characteristics of indium or bismuth having large hydrogen overvoltage to suppress zinc reaction. Specifically, indium or bismuth is added to an electrolytic solution in a positive electrode mixture or to a size in contact with the surface of the zinc can, the surface of the zinc can is covered directly with an indium layer or a bismuth layer, or the like.

Though the above methods are effective in increasing the corrosion resistance of the zinc can during self discharge, namely, when the battery is stored, corrosion of the zinc can, which occurs also after overdischarge and in discharge, cannot be suppressed sufficiently. Accordingly, a hole is formed in the zinc can after overdischarge or in discharge to cause the electrolytic solution from leaking outside the battery through the hole.

While, Patent Document 4 (Japanese Patent Application laid open unexamined Publication No. 6-196155) and Patent Document 5 (Japanese Patent Application laid open unexamined Publication No. 6-196156) disclose that in view of the fact that the amount of corrosion of a zinc can decreases as the grain diameter of zinc becomes small, elements to be added to zinc, such as indium, tin, aluminum, gallium, or the like and the process factors in manufacturing the zinc can, such as hot-rolling temperature, can processing temperature, and the like are adjusted so that the grain diameter of zinc becomes 30 μm or smaller after can formation. These methods attain corrosion resistance equivalent to that in the conventional zinc can to which lead is added.

SUMMARY OF THE INVENTION

According to the methods disclosed in Patent Documents 4 and 5, though a zinc can contains zinc of which grain diameter is substantially equal to that in the conventional zinc can to which lead is added, the actual grain diameter thereof falls in the range between 22 and 30 μm at the most.

With the grain diameter in the range between 22 and 30 μm, the reaction at the surface of the zinc can is uniformed by the increased number of grain boundaries to thus increase the corrosion resistance. In the zinc cans formed by the above methods, however, hole formation is prevented incompletely.

The present invention has been made in view of the foregoing and has its object of providing a manganese dry battery including a negative electrode zinc can excellent in corrosion resistance and a negative electrode zinc can used therein.

The phenomenon of hole formation due to corrosion of the zinc can might progress through the following reaction.

Namely, when a battery discharges, the reaction starts at lines (flaws) caused in can formation or grain boundaries of zinc, as reaction starting points, in the surface of the zinc can and then progresses widely therefrom. In the case where graphite is used as a lubricant for can formation, the graphite serves as one of the reaction starting points. When the reaction progresses inside the zinc can, only the grain boundaries present inside the zinc can serve as the reaction starting points to promote the reaction. In short, the reaction might progress along the grain boundaries as long as the grain boundaries are present inside the zinc can to thus form a hole in the zinc can where the reaction concentrates.

The inventors have arrived, on the basis of the aforementioned study, at a conclusion that: when an element capable of inhibiting the zinc reaction is allowed to be yielded at the grain boundaries, local progress of the reaction along the grain boundaries is inhibited even if the reaction progresses inside the zinc can, thereby uniforming the reaction even inside the zinc can to thus increase the corrosion resistance remarkably.

A manganese dry battery in accordance with the present invention includes a negative electrode zinc can as a battery can made of zinc to which an added element other than zinc is added, wherein the added element is yielded at a grain boundary of the zinc.

With the above arrangement, the zinc reaction in the zinc can can be unformed not only at the surface of the zinc can but also inside the zinc can to suppress leakage of the electrolytic solution caused due to hole formation in the zinc can effectively.

It is preferable that the added element is at least one element selected from the group consisting of Pb, Bi, Ca, Mg, Si, Al, and In. These elements, which have large hydrogen overvoltage, can suppress the zinc reaction caused due to self discharge of the battery to increase the corrosion resistance of the zinc can and to improve further the discharge characteristics of the battery.

Preferably, the negative electrode zinc can is formed of a zinc plate formed by quenching melted zinc containing the added element at a quenching rate in a range between 75 and 100° C./second. Such quick quenching confines the added element to the grain boundaries of zinc.

Preferably, the zinc can is formed by impact molding at a temperature in a range between 20 and 30° C. Impact molding at such low temperature prevents the added element confined (yielded) to the grain boundaries from being taken into the crystals, which is caused due to re-growth of zinc.

The above effects obtained in the present invention are exerted by zinc reaction uniformed by the added element yielded at the grain boundaries of zinc. In view of this, the inventors have arrived at a further conclusion that: when the grain diameter of zinc is reduced by one place or more than ever, the zinc reaction is uniformed further to attain effects equivalent to the effects obtained by yielding the added element at the grain boundaries.

Accordingly, another manganese dry battery in accordance with the present invention includes a negative electrode zinc can as a battery can made of zinc, wherein the negative electrode zinc can is formed of a zinc plate formed by quenching melted zinc containing aluminum in a range between 3 and 80 wt % (more preferably, between 19 and 25 wt %) and casting it.

Quick quenching of the melted zinc containing aluminum of such an amount causes “age hardening” which aluminum exhibits inherently, as will be described later. As a result, the average grain diameter of zinc forming the zinc can can be minimized to approximately 0.01 to 1 μm (0.01 to 0.05 μm in the above more preferable range). This attains a zinc can containing zinc of which grain diameter is smaller than one place or more than ever. Hence, the zinc reaction can be uniformed not only at the surface of the zinc can but also inside the zinc can, thereby effectively suppressing leakage of the electrolytic solution caused due to hole formation in the zinc can.

In a negative electrode zinc can for a manganese dry battery in accordance with the present invention, an added element other than zinc is yielded at a grain boundary of zinc forming the negative electrode zinc can. Preferably, the added element is at least one element selected from the group consisting of Pb, Bi, Ca, Mg, Si, Al, and In.

In another negative electrode zinc can in accordance with the present invention, the negative electrode zinc can is formed of a zinc plate formed by quenching melted zinc containing aluminum in arrange between 3 and 80 wt % and casting it. It is preferable that the zinc has a grain diameter in a range between 0.01 and 1 μm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial sectional view showing a structure of a manganese dry battery in accordance with the present invention.

FIG. 2 is a table evaluating corrosion resistance of manganese dry batteries in the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following description, the same reference numerals are assigned to elements having substantially the same functions for the sake of simple explanation. It should be noted that the present invention is not limited to the following embodiments.

Embodiment 1

FIG. 1 is a sectional view showing a structure of a manganese dry battery in accordance with Embodiment 1 of the present invention, wherein a battery can is formed of a negative electrode zinc can 4 in a bottomed cylindrical form.

As shown in FIG. 1, within the negative electrode zinc can 4, a positive electrode mixture 1 is inserted with a separator 3 containing an electrolytic solution interposed, and a carbon rod 2 as a current collector is inserted in the central part of the positive electrode mixture 1. The upper end opening of the negative electrode zinc can 4 is sealed by a sealant 5. The carbon rod 2 passes through the center hole of the sealant 5 so as to be in contact with a positive electrode 11 while a negative electrode terminal 6 is mounted at the bottom of the negative electrode zinc can 4. The outer peripheral face of the negative electrode zinc can 4 is covered with a plastic tube 8, and a metal jacket 10 is fitted to the outer periphery of the plastic tube 8.

In the negative electrode zinc can 4 in the present embodiment, an added element other than zinc is yielded at the grain boundaries of zinc forming the zinc can 4. When an element capable of inhibiting the zinc reaction in the negative electrode zinc can 4 is allowed to be yielded at the grain boundaries, local progress of the zinc reaction along the grain boundaries is prevented even if the zinc reaction progresses inside the negative electrode zinc can 4. Accordingly, the zinc reaction is uniformed even inside the negative electrode zinc can 4 to suppress effectively leakage of the electrolytic solution caused due to hole formation in the negative electrode zinc can 4. Thus, a manganese dry battery excellent in corrosion resistance can be attained.

The added element may be any material only if it is yielded at grain boundaries of zinc for inhibiting the zinc reaction, but an element having large hydrogen overvoltage, such as PB, Bi, Ca, Mg, Si, Al, In, and the like can suppress the zinc reaction caused due to self discharge of the battery and are therefore preferable in the view point that the discharge characteristics of the battery can be improved.

As the grain diameter of zinc is small, the zinc reaction is further uniformed. Nevertheless, even if the grain diameter is comparatively large (approximately 100 μm, for example), mere yielding of the added element at the grain boundaries causes the zinc reaction to be uniform to increase the corrosion resistance sufficiently.

The experiment performed by the inventors revealed that the leakage caused due to hole formation in a zinc can can be suppressed effectively even when the amount of the added element contained in the melted zinc is in the range between approximately 2 and 20 ppm. The reason why the effects can be obtained even with such a small amount of added element might be uniform dispersion of the added element at the grain boundaries.

The zinc can in which the added element other than zinc is yielded at the grain boundaries can be manufactured by the following method.

Namely, the zinc can is manufactured in such a manner that: zinc containing the added element is melted and quenched to form (cast) a zinc solid; the cast zinc solid is rolled into a plate shape and the thus rolled plate is punched out to form a circular piece; and the circular piece is impact molded to form a zinc can in a bottomed cylindrical form.

Herein, the inventors paid attention to quenching rate of the melted zinc containing the added element to find that quenching at 75 to 100° C./second achieves confinement of the added element to the grain boundaries of zinc

It was also found that it is preferable for forming a zinc can in a bottomed cylindrical form from a zinc plate cast and rolled in the above method to perform impact molding at a temperature of 20 to 30° C. (room temperature). For example, impact molding at a temperature equal to the temperature thereof performed ordinarily (approximately 180° C., for example) causes the added element confined to the grain boundaries to be taken into the crystals. This might be because the added element confined to the grain boundaries is taken into the crystals by re-growth of zinc at high-temperature impact molding. Accordingly, impact molding is performed preferably within the temperature range that causes no re-growth of zinc (typically, room temperature).

Embodiment 2

While yielding of the added element other than zinc at the grain boundaries of zinc uniforms the zinc reaction in Embodiment 1 of the present invention, the zinc reaction can be uniformed by reducing the grain diameter of zinc by one place or more than ever.

In the present embodiment, a negative electrode zinc can 4 used in a manganese dry battery is formed of a zinc plate obtained by quenching and casting melted zinc containing aluminum of 3 to 80 weight %.

Quick quenching of the melted zinc containing aluminum of such an amount minimizes the grain diameter of zinc forming the zinc can 4 to approximately 0.01 to 1 μm. This attains a zinc can in which zinc has a grain diameter one place or more smaller than ever. As a result, the zinc reaction is uniformed not only at the surface of the zinc can but also inside the zinc can, thereby effectively suppressing leakage of the electrolytic solution caused due to hole formation in the zinc can.

When the content of aluminum is set below 3 wt %, the effect of minimizing the grain diameter obtained by adding aluminum is less exerted. On the other hand, when the content thereof is set larger than 80 wt %, the necessary amount of discharge capacity of the battery cannot be secured. When the content thereof is set within the range between about 19 to 25 wt %, the grain diameter of zinc can be further minimized to approximately 0.01 to 0.05 μm.

The diameters of crystal grains distribute in a given pattern (normal distribution, for example), and the term, “grain diameter” herein means an average grain diameter. Specifically, the diameters of individual crystal grains present in a given region are measured, and the average value thereof is calculated and called the “grain diameter.”

Each diameter of the crystal grains can be measured by various methods. For example, in a case using an optical microscope for observation: a predetermined number of samples are prepared; a region presenting the same color (a region of a single reflected plane) or a region enclosed by a grain boundary is defined as a crystal grain in each sample; the number of crystal grains per a predetermined line length is counted to calculate an average grain size of the crystal grains in each sample; and an average value is calculated as the “grain diameter” from the thus calculated average grain sizes thereof in each sample. In the case where the grain diameter is rather small, an electron microscope may be used.

A zinc can in which zinc has a fine grain diameter of 1 μm or smaller may be manufactured by the following method.

Namely, the zinc can is manufactured by a series of the steps of casting melted zinc; rolling the cast zinc solid; and performing impact molding, as described above. The inventors have focused attention to the casting step to find that quick quenching of the melted zinc containing aluminum of a predetermined amount (3 to 80 wt %) at a rate in a range between 50 and 200° C./second achieves minimization the grain diameter of zinc to 1 μm or smaller.

Age hardening, which aluminum exhibits inherently, might be the reason why such fine crystal grains are formed. In detail, when melted zinc containing aluminum is quenched quickly, aluminum, which will be yielded at low temperature, remains intercrystallized (melted). The thus intercrystallized aluminum alloy is in an unstable state and, therefore, tries to be in a stable state as time lapses to be yielded finely and uniformly. As a result, the crystal grains are minimized.

It is noted that an element, such as Pb, Bi, Ca, Mg, Si, In, or the like may be added to zinc in the present embodiment for yielding the added element at the grain boundaries of the zinc can. By doing so, the reaction of the zinc can be uniformed further and the corrosion resistance of the manganese dry battery increases.

WORKING EXAMPLES

Results obtained by evaluating the corrosion resistance of manganese dry batteries in the present invention will be explained on the basis of the working examples. It is noted that the present invention is not limited to the following working examples.

Battery 1

Comparative Example

A. Manufacture of Zinc Can

Zinc having a purity of 99.99 wt % to which Pb of 1000 ppm is added was melted at approximately 500° C. by a melting furnace to obtain melted zinc. The thus obtained melted zinc was quenched to 180 to 200° C. at a quenching rate of 70° C./second, was rolled into a plate having a predetermined thickness, and was then punched out by pressing to obtain a circular piece having a predetermined size. A lubricant of which main component is graphite powder or a lubricant containing zinc stearate was applied to the piece, and the thus applied piece was agitated in a mixer to allow the lubricant to be pressed and adhere to the surface of the zinc piece. Finally, impact molding was performed, thereby obtaining a zinc can 4 in a bottomed cylindrical form for an AA (R6) battery. The temperature at impact molding was approximately 180° C. The weight of the negative electrode can was 3.5 g, and graphite or zinc stearate adhering to the piece was approximately 0.1 mg.

B. Preparation of Positive Electrode Mixture

Manganese dioxide of 5 g, conductive carbon black of 1 g, and an electrolytic solution of 4 g containing ammonium chloride of 1 wt %, zinc chloride of 29 wt %, and water of 70 wt % were mixed, and zinc oxide of 1 wt % was added to and mixed with the thus obtained mixture, and then, the final mixture was molded to obtain a cylindrical positive electrode mixture.

C. Assembly of Manganese Dry Battery

With the use of the zinc can in R6 size obtained as above, an AA manganese dry battery shown in FIG. 1 was manufactured by the following process.

The cylindrical positive electrode mixture 1 was inserted into the zinc can 4 with the separator 3 interposed. On the separator 3, a size paste of 40 mg made of an aqueous solution of starch, alcohol, and a surfactant was coated. Indium or bismuth may be added to the size paste. Then, the carbon rod 2 obtained by hardening carbon powder was inserted at the central part of the positive electrode mixture 1.

The sealant 5 was prepared which is made of polyolefin-based resin and has a hole at the central part through which the carbon rod 2 is to be inserted. An upper insulator 9 was prepared by punching out a plate into an annular shape of which hole is at the center, and was then arranged on the positive electrode mixture 1. The carbon rod 2 was allowed to pass through the sealant 5 and the upper insulator 9 to be in contact at the upper part thereof to a positive electrode terminal 11 so as to serve as a current collector of the current of the positive electrode.

The plastic tube 8 formed of a resin film capable of being thermally contracted was arranged around the zinc can 4 for ensuring insulation. The plastic tube 8 was allowed to cover at the upper end part thereof the upper peripheral part of the sealant 5 and to cover at the lower end part thereof the lower face of a seal ring 7.

The positive electrode terminal 11 formed of a tinplate has a flat flange part and a cap-shaped central part covering the upper end of the carbon rod 2. A resin-made insulation ring 12 was provided at the flat flange part of the positive electrode terminal 11. A bottom insulator 13 was provided between the bottom of the positive electrode mixture 1 and the negative electrode zinc can 4 for securing insulation. The seal ring 7 was arranged around the flat outer periphery of the negative electrode terminal 6

A metal jacket 10 formed of a cylindrical tinplate was arranged around the plastic tube 8. The lower end part of the metal jacket 10 is folded inward, the upper end part thereof is curled inward, and the tip end of the upper end thereof is allowed to be in contact with the insulator ring 12.

Battery 2 to Battery 7

A. Manufacture of Zinc Can

Zinc having a purity of 99.99 wt % to which any of the added elements listed in the table of FIG. 2 (Pb of 1000 ppm, Bi of 20 ppm, Ca of 2 ppm, Mg of 5 ppm, Si of 5 ppm, Al of 10 ppm, or In of 15 ppm) is added was melted at approximately 500° C. by a melting furnace to obtain melted zinc. The thus obtained melted zinc was quenched to room temperature (20 to 30° C.) at a quenching rate of 75 to 100° C./second, was rolled into a plate having a predetermined thickness, and was then punched out by pressing to obtain a circular piece having a predetermined size. A lubricant of which main component is graphite powder or a lubricant containing zinc stearate was applied to the piece, and the thus applied piece was agitated in a mixer to allow the lubricant to be pressed and adhere to the surface of the zinc piece. Finally, impact molding was performed, thereby obtaining a zinc can 4 in a bottomed cylindrical form for an AA (R6) battery. The temperature at impact molding was room temperature (20 to 30° C.). The weight of the negative electrode can was 3.5 g, and graphite or zinc stearate adhering to the piece was approximately 0.1 mg.

B. Preparation of Positive Electrode Mixture and Assembly of Manganese Dry Battery

Preparation of the positive electrode mixtures and assembly of the manganese dry batteries are the same as those in the case of Battery 1.

Battery 8 to Battery 17

A. Manufacture of Zinc Can

Zinc having a purity of 99.99 wt % to which any of the added elements listed in the table of FIG. 2 (Pb of 500 ppm and/or Bi of 30 ppm) is added was melted at approximately 700° C. by a melting furnace to obtain melted zinc. The thus obtained melted zinc was quenched to room temperature (20 to 30° C.) at a quenching rate of 100° C./second, was rolled into a plate having a predetermined thickness, and was then punched out by pressing to obtain a circular piece having a predetermined size. A lubricant of which main component is graphite powder or a lubricant containing zinc stearate was applied to the piece, and the thus applied piece was agitated in a mixer to allow the lubricant to be pressed and adhere to the surface of the zinc piece. Finally, impact molding was performed to thus obtain a zinc can 4 in a bottomed cylindrical form for an AA (R6) battery. The temperature at impact molding was room temperature (20 to 30° C.). The weight of the negative electrode can was 3.5 g, and graphite or zinc stearate adhering to the piece was approximately 0.1 mg.

B. Preparation of Positive Electrode Mixture and Assembly of Manganese Dry Battery

Preparation of the positive electrode mixtures and assembly of the manganese dry batteries are the same as those in the case of Battery 1.

(Measurement of Grain Diameter of Zinc in Zinc Can)

Zinc inside each zinc can (transverse section) was observed by an optical microscope for measuring the sizes of the crystal grains. The samples of the zinc cans were embedded in epoxy resin and were cut so as to expose the transverse sections of the zinc cans. Then, the exposed surfaces of the zinc cans were subjected to wet polishing for mirror finishing. Wet polishing was performed using a mixed solution of water and grains of aluminum oxide. The polished faces were immersed in a solution of ethanol and hydrochloric acid (volume ratio of 97:3) for approximately ten seconds for chemical etching, were washed with water, and were then dried. Thereafter, the samples were observed by the optical microscope for specifying the crystal grains from the observed grain boundaries to measure each size of the crystal grains.

(Check of Added Element Present at Grain Boundary in Zinc Can)

The elements present at the grain boundaries of zinc inside the zinc cans (transverse section) were measured by element distributive analysis using an electron probe micro-analyzer (EPMA). The samples were prepared by the same method as above. In order to check the added elements present at the grain boundaries, element mapping was performed on the sections of the zinc cans, and the respective grain boundaries obtained from mapping and optical microphotograph were compared with each other.

(Evaluation of Manganese Dry Battery)

The following evaluation of corrosion resistance was performed on each manganese dry battery obtained as above.

The batteries were allowed to discharge (overdischarge) at a temperature of 20±2° C. with a load of 3.9Ω applied until the end voltage became 0.1 V. Then, the number of batteries in which leakage occurs were counted, and the average discharge capacities thereof were evaluated. The results of the evaluation are indicated in the table of FIG. 2.

A. Effects Exerted by Added Element Yielded at Grain Boundary

As indicated in the table of FIG. 2, holes were formed in the zinc cans of all of the sample batteries of Battery 1 (comparative example) to cause leakage in the batteries after discharge. In contrast, the number of leakage occurrences after discharge was reduced to one half or less thereof in Battery 2 to Battery 7, which reveals that the batteries are superior to Battery 1. As to Battery 4 to Battery 7, the number of leakage occurrences after discharge was equal to or smaller than one fourth of that in Battery 1, which means more excellent results. In each of Battery 2 to Battery 7, it was recognized that each added element (including two or more added elements) is yielded at the grain boundaries of zinc in the zinc cans.

The above results lead to conclusions that: yielding of the added elements other than zinc at the grain boundaries achieves an increase in corrosion resistance of the manganese dry batteries; Pb, Bi, Ca, Mg, Si, Al, and In are effective as the added element; the effects of the present invention can be exhibited even with the crystal grains having a comparatively large grain diameter of approximately 100 μm; and the effects of the present invention can be exhibited more when the grain diameter is 20 μm or smaller.

B. Effects by Size Reduction of Grain Diameter

As indicated in the table of FIG. 2, the number of leakage occurrences after discharge was reduced to one fifth or smaller out of 20 sample batteries in each of Battery 8 to Battery 17. No leakage occurred after discharge in Battery 11 to Battery 13.

The above results lead to conclusion that: when the content of aluminum is 3 wt % or larger, the grain diameter of zinc reduces to 1 μm or smaller to increase the corrosion resistance of the manganese dry battery. Further, when the content of aluminum is in the range between 19 and 25 wt %, the grain diameter of zinc reduces to 0.1 μm or smaller to exhibit more the effects of the present invention. It is noted that the content of aluminum of 85 wt % or larger leads to lowering of the discharge capacity to 850 mAh. This might be because of lowering of electron conductivity of the zinc can caused due to the increased amount of aluminum. Accordingly, the content of aluminum is set preferably within the range between 3 and 80 wt %, more preferably, the range between 19 and 25 wt %.

Heretofore, the preferred embodiments of the present invention are described. The above description, however, does not limit the present invention, and various modifications are possible.

Claims

1. A manganese dry battery comprising:

a negative electrode zinc can as a battery can made of zinc to which an added element is added,

wherein the added element other than zinc is yielded at a grain boundary of the zinc.

2. The manganese dry battery of claim 1,

wherein the added element is at least one element selected from the group consisting of Pb, Bi, Ca, Mg, Si, Al, and In.

3. The manganese dry battery of claim 1,

wherein the negative electrode zinc can is formed of a zinc plate formed by quenching melted zinc containing the added element at a quenching rate in a range between 75 and 100° C./second.

4. The manganese dry battery of claim 3,

wherein the negative electrode zinc can is formed by impact molding at a temperature in a range between 20 and 30° C.

5. The manganese dry battery of claim 2,

wherein an amount of the added element is in a range between 2 and 20 ppm.

6. The manganese dry battery of claim 1,

wherein the zinc has a grain diameter of 100 μm or smaller.

7. A manganese dry battery comprising:

a negative electrode zinc can as a battery can made of zinc,

wherein the negative electrode zinc can is formed of a zinc plate formed by quenching melted zinc containing aluminum in a range between 3 and 80 wt % and casting it.

8. The manganese dry battery of claim 7,

wherein the zinc has a grain diameter in a range between 0.01 and 1 μm.

9. The manganese dry battery of claim 7,

wherein a content of the aluminum is in a range between 19 and 25 wt %.

10. The manganese dry battery of claim 9,

wherein the zinc has a grain diameter in a range between 0.01 and 0.05 μm.

11. The manganese dry battery of claim 7,

wherein the negative electrode zinc can is formed of a zinc plate formed by quenching the melted zinc at a quenching rate in a range between 50 and 200° C./second and casting it.

12. A negative electrode zinc can for a manganese dry battery, essentially consisting of zinc,

wherein an added element other than zinc is yielded at a grain boundary of the zinc.

13. The manganese dry battery of claim 12,

wherein the added element is at least one element selected from the group consisting of Pb, Bi, Ca, Mg, Si, Al, and In.

14. A negative electrode zinc can for a manganese dry battery, essentially consisting of zinc,

wherein the negative electrode zinc can is formed of a zinc plate formed by quenching melted zinc containing aluminum in arrange between 3 and 80 wt % and casting it.

15. The negative electrode zinc can of claim 14,

wherein the zinc has a grain diameter in a range between 0.01 and 1 μm.