| 摘要 |
Provided is a porous multi-layer film having two or more layers that is used as a separator for battery. In the film, more than 2 layers have different porosities and pore sizes. The film has a thickness of 9 to 50 μm, a machine direction (MD) loop stiffness of 0.008 mg/μm or more, puncture strength of 0.15 N/μm or more, permeability of 1.5×10−5 Darcy or more, shut-down temperature of 140° C. or less, melt-down temperature of 170° C. or more, a transverse direction (TD) maximum shrinkage of 25% or less in Thermomechanical Analysis (TMA) under a load of 1 mN/(1 μm×6 mm), and melt down temperature of 160° C. or more. Since the porous multi-layer film shows excellent thermal stability at high temperature and electrolyte retaining property due to a dual pore structure, the film shows a superior effect when used as a separator for high-capacity/high-power lithium ion battery. |
