SEPARATOR FOR NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY AND NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY
A separator for a non-aqueous electrolyte secondary battery includes a first layer containing thermoplastic fibers, and a second layer formed on at least one side of the first layer and containing cellulose fibers as a main component. The first layer includes a mixed portion in which the thermoplastic fibers and the cellulose fibers are mixed, the mixed portion being disposed at an interface with the second layer. A total weight per area of the cellulose fibers contained in the second layer and the mixed portion is more than 5 g/m 2 and 20 g/m 2 or less.
1 . A separator for a non-aqueous electrolyte secondary battery, the separator comprising:
a first layer containing thermoplastic fibers; and
a second layer formed on at least one side of the first layer and containing cellulose fibers as a main component,
wherein the first layer includes a mixed portion in which the thermoplastic fibers and the cellulose fibers are mixed, the mixed portion being disposed at an interface with the second layer, and
a total weight per area of the cellulose fibers contained in the second layer and the mixed portion is more than 5 g/m 2 and 20 g/m 2 or less.
2 . The separator according to claim 1 , wherein the total weight per area of the cellulose fibers is 8 to 17 g/m 2 .
3 . The separator according to claim 1 , wherein the second layer has a thickness of 5 μm or more.
4 . The separator according to claim 1 , wherein the cellulose fibers have an average fiber diameter of 0.05 μm or less.
5 . The separator according to claim 1 , wherein the mixed portion has a thickness of at least 1 μm or more from a surface of the first layer.
6 . The separator according to claim 1 , wherein the thermoplastic fibers have an average fiber diameter of 5 to 25 μm, an average fiber length of 5 mm or more, and a weight per area of 3 to 15 g/m 2 .
7 . The separator according to claim 1 , wherein a maximum pore size measured with a Perm-Porometer is 0.2 μm or less.
8 . A non-aqueous electrolyte secondary battery comprising:
a positive electrode;
a negative electrode;
the separator according to claim 1 , the separator being interposed between the positive electrode and the negative electrode; and
a non-aqueous electrolyte.