Separator for lithium secondary battery, and lithium secondary battery comprising same
Provided are a separator for a lithium secondary battery including a substrate and a heat-resistance porous layer disposed on at least one surface of the substrate and including a cross-linked binder, wherein the cross-linked binder has a cross-linking structure of a compound represented by Chemical Formula 2, and a lithium secondary battery including the same.
1. A separator for a lithium secondary battery, comprising:
a substrate, and
a heat-resistance porous layer disposed on at least one surface of the substrate and including a cross-linked binder,
wherein the cross-linked binder has a cross-linking structure formed from a compound represented by Chemical Formula 2,
wherein, in Chemical Formula 2,
X 1 to X 3 are an oxyethylene group, respectively,
X 4 is an oxyethylene group or a C1 to C10 alkyl group, when X 4 is the oxyethylene group, n 4 is an integer ranging from 1 to 10 and m is 1 and when X 4 is the C1 to C10 alkyl group, n 4 is 1 and m is 0,
R 1 to R 4 are a functional group of a (meth)acrylate group, a hydroxy group, a carboxyl group, an ester group, a cyanate group, an isocyanate group, an amino group, a thiol group, a C1 to C10 alkoxy group, a vinyl group, or a heterocyclic group,
each of a 1 to a 4 are an integer ranging from 1 to 10,
each of n 1 to n 3 are an integer ranging from 0 to 10, and at least one of n 1 to n 4 is an integer ranging from 1 to 10,
wherein the heat-resistance porous layer further comprises a non-crosslinked binder,
wherein the non-crosslinked binder comprises polyvinylidene fluoride (PVdF), a polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) copolymer, polymethylmethacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-vinylacetate copolymer, polyethyleneoxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinyl alcohol, cyanoethyl cellulose, cyanoethylsucrose, pullulan, an acrylonitrile-styrene-butadiene copolymer, or a combination thereof, and
wherein each shrinkage ratio in a machine direction (MD) and a transverse direction (TD) of the separator is less than or equal to 5% according to Equation 1,
Shrinkage ratio (%)=[( LO−L 1)/ LO ]×100 [Equation 1]
wherein, in Equation 1, LO indicates an initial length of a separator and L1 indicates a length of a separator after being allowed to stand at 200° C. and for 10 minutes.
2. A separator for a lithium secondary battery, comprising:
a substrate, and
a heat-resistance porous layer disposed on at least one surface of the substrate and including a cross-linked binder,
wherein the cross-linked binder has a cross-linking structure formed from a compound represented by Chemical Formula 2,
wherein, in Chemical Formula 2,
X 1 to X 3 are an oxyethylene group, respectively,
X 4 is an oxyethylene group or a C1 to C10 alkyl group, when X 4 is the oxyethylene group, n 4 is an integer ranging from 1 to 10 and m is 1 and when X 4 is the C1 to C10 alkyl group, n 4 is 1 and m is 0,
R 1 to R 4 are a functional group of a (meth)acrylate group, a hydroxy group, a carboxyl group, an ester group, a cyanate group, an isocyanate group, an amino group, a thiol group, a C1 to C10 alkoxy group, a vinyl group, or a heterocyclic group,
each of a 1 to a 4 are an integer ranging from 1 to 10,
each of n 1 to n 3 are an integer ranging from 0 to 10, and at least one of n 1 to n 4 is an integer ranging from 1 to 10,
wherein the heat-resistance porous layer further comprises a non-crosslinked binder,
wherein the non-crosslinked binder comprises polyvinylidene fluoride (PVdF), a polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) copolymer, polymethylmethacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-vinylacetate copolymer, polyethyleneoxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinyl alcohol, cyanoethyl cellulose, cyanoethylsucrose, pullulan, an acrylonitrile-styrene-butadiene copolymer, or a combination thereof, and
wherein the compound includes a compound represented by Chemical Formula 3 or 4:
wherein, in Chemical Formulae 3 and 4,
R 5 is a C1 to C10 alkyl group,
each of n 5 to n 7 are an integer of 1 to 5, and
each of a 5 to a 12 are an integer of 1 to 10.
3. The separator for a lithium secondary battery of claim 1 , wherein the heat-resistance porous layer includes a filler including an inorganic particle, an organic particle, or a combination thereof.
4. The separator for a lithium secondary battery of claim 3 , wherein the filler is included in an amount of 50 wt % to 95 wt % based on a total amount of the cross-linked binder and the filler.
5. A lithium secondary battery comprising the separator according to claim 1 .