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[0001]1. Field of the Invention[0002]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.[0003]2. Description of Related Art[0004]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.[0005]In view of environmental pollution, other approaches without using lead for improving the corrosion resistance of the zinc cans have been examined.[0006]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 ...

AI Technical Summary

Benefits of technology

[0010]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.

[0022]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.

Problems solved by technology

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.

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.

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