Secondary battery and manufacturing method thereof

A secondary battery having a simplified structure by which a lead of a safety device can be adhered to the battery includes an electrode unit having a positive electrode plate, a negative electrode plate and a separator disposed therebetween, a can having a bottom portion and made of aluminum or an aluminum alloy, the can in which the electrode unit and an electrolytic solution are accommodated and sealed, and a surface coating provided on at least an outer surface of the bottom portion of the can to which the lead is attached. In order to prevent contamination of a probe of an initial charging/discharging device a surface coating is formed on at least an outer surface of a cap plate.