Separator for Lithium Secondary Battery and Method for Manufacturing the Same

Abstract

A separator for a lithium secondary battery, a method of making the same, and a lithium secondary battery including the same is disclosed herein. In some embodiments, a separator for a lithium secondary battery including a porous polyolefin substrate having a tan(δ) of 0.3 or less. The tan(δ) is determined by Formula 1 at a temperature of 230° C. and an angular frequency of 0.1 rad/s: tan(δ)=G″/G′  [Formula 1] wherein G′ is a storage modulus of the polyolefin and G″ is a loss modulus of the polyolefin. The separator has a low viscosity but high elasticity at high temperature, maintains strength at high temperature, and has resistance against external force at high temperature. A lithium secondary battery including the separator has improved safety.

Dependencies are inferred from the claim text.