ELECTRODE GROUP FOR ALKALINE SECONDARY BATTERY AND MANUFACTURE THEREOF

PROBLEM TO BE SOLVED: To suppress an active material from being parted from a positive electrode upper rim part and efficiently prevent inner short circuit by melting a separator in the part facing a positive electrode tab installation part and forming the part to be a coating. SOLUTION: A separator 33 having a surface area which is two times as large as that of a positive electrode plate 31 is folded in two to sandwich the positive electrode plate 31. Two side lines 33b of the folded separator 33 are melted and stuck to each other by an ultrasonic welding apparatus to form into a bag-like shape and to unit the positive electrode plate 31 and the separator 33 and at the same time, the parts of the separator facing to the upper rim part 31a of the positive electrode plate 31 including the installation part of the positive electrode tab in both front and rear sides of the united separator are melted. The melded parts, of the separator melted by such a manner are formed into coatings and lose liquid permeative property and prevent penetration with an electrolytic solution. That is, a part to which a liquid-impervious film adheres is formed in the surface of the positive electrode plate 31 and contact between an electrolytic solution and a positive electrode active material is suppressed. Consequently, electric communication in the upper rim part of the positive electrode plate 31 is suppressed at the time of practical operation and the formation of γ-nickel oxyhydroxide is suppressed. Following that, expansion and deformation of the positive electrode plate 31 can be suppressed and the active material separation can be prevented.