SEPARATOR FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERIES, AND NONAQUEOUS ELECTROLYTE SECONDARY BATTERY
A separator for nonaqueous electrolyte secondary batteries according to one embodiment of the present disclosure comprises a porous base material and a heat-resistant porous film that is arranged on at least one surface of the porous base material so as to face an electrode of a nonaqueous electrolyte secondary battery. The heat-resistant porous film contains a filler and a binder; and at least a part of a facing part A of the heat-resistant porous film, said facing part A facing the edge portion of the electrode, has a higher binder content than a facing part B of the heat-resistant porous film, said facing part B facing the central portion of the electrode.
1 . A separator for a non-aqueous electrolyte secondary battery comprising:
a porous substrate; and
a heat-resistant porous film that is disposed on at least one surface of the porous substrate so as to face an electrode of a non-aqueous electrolyte secondary battery,
wherein the heat-resistant porous film contains a filler and a binder, and
a content of the binder in at least one part of facing parts A of the heat-resistant porous film facing an edge portion of the electrode is higher than that in a facing part B of the heat-resistant porous film facing a central portion of the electrode.
2 . The separator for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the content of the binder contained in the at least one part of the facing parts A of the heat-resistant porous film is 5% by mass to 15% by mass, and
the content of the binder contained in the facing part B of the heat-resistant porous film is 1% by mass to 10% by mass.
3 . The separator for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the heat-resistant porous film is disposed on both surfaces of the porous substrate.
4 . A non-aqueous electrolyte secondary battery comprising the electrode and the separator for a non-aqueous electrolyte secondary battery according to claim 1 .