ZINC ALLOY POWDER FOR THE NEGATIVE ELECTRODE OF A MERCURY-FREE ALKALINE BATTERY AND ITS MANUFACTURE

摘要

PURPOSE:To reduce the amount of corrosion of the negative electrode and reduce the amount of hydrogen gas generation by preparing the negative electrode from a zinc alloy powder which contains zinc, tin and an alkali metal as essential components and at least a specified percentage of which consists of a powder with specific configurational characteristics. CONSTITUTION:A zinc alloy containing zinc, tin and an alkali metal as essential components is molten and atomized in an atmosphere containing at most 0.4vol% of oxygen. It is preferable to use sodium, potassium or lithium as the alkali metal. It is preferable to adjust the contents of the alkali metal and tin to within the ranges of 0.001-2.0wt% and 0.0.5-0.8wt% respectively. At least 50wt% of the thus prepared zinc alloy powder consists of ellipsoidal, cocoon-like or teardrop-like particles having a long axis length of at most 0.3mm and a short axis length of at least 0.05mm. By the means mentioned above, a short circuit current can be abundantly produced. Additionally, because there are no projections on the surface of the particles, hydrogen gas generation is suppressed.