| 摘要 |
PROBLEM TO BE SOLVED: To provide a bag-shaped separator exhibiting high binding strength even under high temperature, and to provide a safe lithium ion secondary battery using the same.SOLUTION: In a multilayer separator including a heat-resistant porous layer composed of resin having a melting point or a glass transition temperature of 200°C or higher, and a polyolefin porous layer composed of polyolefin resin having a melting point or a glass transition temperature of 160°C or higher, the polyolefin porous layers are made to face each other at the end thereof, and the polyolefin porous layers facing each other are thermally fused as a joint 41 thus obtaining a bag-shaped separator 40. In the joint 41, the polyolefin resin of the polyolefin porous layer soaks into the heat-resistant porous layer. |
