The present invention provides a secondary battery comprising a battery package which encloses the outer perimeter of the secondary battery and covers the entire outer surface of positive and negativeelectrodes and a portion of each terminal of the positive and negative electrodes, wherein the battery package is formed of a laminate film comprising an outer polymer layer, an inner aluminum layerand an adhesive layer formed on a portion of the inner surface of the aluminum layer, the aluminum layer of the battery package being electrically connected with either of the positive and negative terminals. In another aspect, the invention provides a secondary battery comprising a battery package which encloses the outer perimeter of the secondary battery and covers the entire outer surface of positive and negative electrodes and a portion of each terminal of the positive and negative electrodes, wherein the battery package is formed of a laminate film comprising an outer polymer layer, an inner aluminum layer and an adhesive layer formed on a portion of the inner surface of the aluminum layer, and further comprises at least one electrically conductive metal foil on at least one of the outer upper and lower surfaces thereof, and each of the electrically conductive metal foil is electrically connected with either of the positive and negative terminals. In the inventive secondary battery, current occurring in conditions such as nail penetration can flow to either the aluminum layer of the package or the metal foil outside the package so as to inhibit heat generation inside the battery, thus improving the safety of the battery.