Patent ID: 8216721

Claim:
A sealed battery comprising an electrode group provided by winding or stacking a positive electrode including a current collector carrying an active material layer thereon, a negative electrode including a current collector carrying an active material layer thereon and a separator interposed therebetween, wherein at least one of the current collector of the positive electrode and the current collector of the negative electrode is exposed at an end thereof and the exposed end is welded to a current collector terminal, the active material layer formed on the surface of the at least one of the current collectors welded to the current collector terminal is covered with a heat resistant porous film and a vertical end edge of the separator is flush with or positioned inside relative to a vertical end edge of the heat resistant porous film, said vertical end edge of said separator and said vertical end edge of said heat resistant porous film being adjacent to the exposed end of the current collector which is welded to the current collector terminal, said vertical end edge of said separator, said vertical end edge of the heat resistant porous film and a vertical end edge of said at least one of the current collectors extend parallel with one another, and the heat resistant porous film has a melting point higher than that of the separator and has a thermal conductivity lower than that of the current collector.