Separator for lithium secondary batteries with improved heat resistance
A separator for a lithium secondary battery, the separator including a separator substrate including a porous polymer resin and a heat resistance layer on at least one side of the separator substrate. The heat resistance layer includes a phenolic resin configured to be hardened when heated. The heat shrinkage at a high temperature is improved, and it is possible to prevent short circuit between electrodes.
1 . A separator for a lithium secondary battery, the separator comprising:
a separator substrate comprising a porous polymer resin; and
a heat resistance layer on at least one side of the separator substrate, the heat resistance layer comprising a phenolic resin configured to be hardened by self-curing when heated,
wherein the phenolic resin comprises a resol-containing phenolic resin, and the resol-containing phenolic resin is present in the heat resistance layer in an amount ranging from 0.5 wt % to 2.0 wt % based on a total solid content of the heat resistance layer, and
wherein a loading amount of the heat resistance layer on the separator substrate is 0.47 g/m 2 or more and less than 2.0 g/m 2 .
2 . The separator according to claim 1 , wherein an inorganic layer is present between the separator substrate and the heat resistance layer.
3 . The separator according to claim 1 , wherein a machine direction and a transverse direction heat shrinkage of the separator at 150° C. is 60% or less.
4 . The separator according to claim 1 , wherein
an inorganic layer is present on a first surface of the separator substrate, and
the heat resistance layer is present on an upper surface of the inorganic layer and a second surface of the separator substrate on which the inorganic layer is not formed.
5 . The separator according to claim 1 , wherein the separator is an aqueous separator.
6 . A cylindrical lithium secondary battery having a structure in which an electrode assembly comprising the separator according to claim 1 is received in a cylindrical battery case.
7 . A battery pack comprising the cylindrical lithium secondary battery according to claim 6 as a unit cell, wherein the battery pack is suitable for use as an energy source of an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or an energy storage system.