| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery with low air resistance and excellent output characteristics as a battery while ensuring reliability as a separator.SOLUTION: In the multilayer separator and lithium ion secondary battery using the same, the multilayer separator is structured so that two layers of porous films of a first porous films and a second porous films are layered and one of the porous films has an elongated hole extending in the thickness direction. |
