Separator including coating layer with ethylenically unsaturated binder, and secondary battery including polymer network formed by gel polymer electrolyte and ethylenically unsaturated binder in coating layer of separator

1. A lithium secondary battery comprising:

a positive electrode;

a negative electrode;

a separator; and

a gel polymer electrolyte disposed between the positive electrode and the negative electrode and the separator, comprising a polymer of an oligomer containing a (meth)acrylate group,

wherein the separator, comprises:

a substrate; and

a coating layer formed on a surface of the substrate,

wherein

the coating layer includes an organic binder and inorganic particles,

the organic binder comprises an ethylenically unsaturated group positioned at an end portion or a side portion of a polymer including at least one unit selected from the group consisting of Formula X-1 and Formula X-2, and

the separator comprises a polymer network in a three-dimensional structure of a polymer of the organic binder containing the ethylenically unsaturated group and the oligomer containing a (meth)acrylate group:

wherein, in Formula X-1, m1 is an integer of 1 to 100,

wherein, in Formula X-2, m2 and m3 are each independently an integer of 1 to 100.

2. The secondary battery of claim 1 , wherein the gel polymer electrolyte is formed by injecting a gel polymer electrolyte composition including the oligomer into a battery case and then curing the composition.

3. The secondary battery of claim 1 , wherein the ethylenically unsaturated group is at least one selected from the group consisting of a vinyl group, an acryloxy group and a methacryloxy group.

4. The secondary battery of claim 1 , wherein the organic binder is included in an amount of 1 part by weight to 80 parts by weight based on 100 parts by weight of the coating layer.

5. The secondary battery of claim 1 , wherein the oligomer further contains an oxyalkylene group.

6. The secondary battery of claim 1 , wherein the oligomer is represented by Formula 1 below:

A-C 1 -A′  [Formula 1]

wherein, in Formula 1, A and A′ are each independently a unit containing the (meth)acrylate group, and C 1 is a unit containing an oxyalkylene group.

7. The secondary battery of claim 1 , wherein the oligomer comprises at least one compound selected from the group consisting of the compounds represented by Formula 1-1 to Formula 1-5 below:

wherein, in Formula 1-1, n1 is an integer of 1 to 20,000,

wherein, in Formula 1-2, n2 is an integer of 1 to 20,000 1

wherein, in Formula 1-3, n3 is an integer of 1 to 20,000,

wherein, in Formula 1-4, n4 is an integer of 1 to 20,000,

wherein, in Formula 1-5, n5 is an integer of 1 to 20,000.

8. The secondary battery of claim 1 , wherein the oligomer comprises a compound represented by Formula 1-1:

wherein, in Formula 1-1, n1 is an integer of 1 to 20,000.

9. The secondary battery of claim 1 , wherein the oligomer comprises a compound represented by Formula 1-2:

wherein, in Formula 1-2, n2 is an integer of 1 to 20,000.

10. The secondary battery of claim 1 , wherein the oligomer comprises a compound represented by Formula 1-3:

wherein, in Formula 1-3, n3 is an integer of 1 to 20,000.

11. The secondary battery of claim 1 , wherein the oligomer comprises a compound represented by Formula 1-4:

wherein, in Formula 1-4, n4 is an integer of 1 to 20,000.

12. The secondary battery of claim 1 , wherein the oligomer is represented by Formula 2 below:

wherein, in Formula 2, A and A′ are each independently a unit containing the (meth)acrylate group, B and B′ are each independently a unit containing an amide group, C 2 and C 2 ′ are each independently a unit containing an oxyalkylene group, D is a unit containing a siloxane group, and 1 is an integer of 1 to 200.

13. The secondary battery of claim 1 , wherein the oligomer comprises at least one compound selected from the group consisting of the compounds represented by Formula 2-1 to Formula 2-5 below:

wherein, in Formula 2-1, k3 and k4 are each independently an integer of 1 to 30, g5 is an integer of 1 to 400, and 11 is an integer of 1 to 400,

wherein, in Formula 2-2, k5 and k6 are each independently an integer of 1 to 30, g6 is an integer of 1 to 200, and 12 is an integer of 1 to 200,

wherein, in Formula 2-3, k7 and k8 are each independently an integer of 1 to 30, g7 is an integer of 1 to 400, and 13 is an integer of 1 to 200,

wherein, in Formula 2-4, k9 and k10 are each independently an integer of 1 to 30, g8 is an integer of 1 to 400, and 14 is an integer of 1 to 200,

wherein, in Formula 2-5, k11 and k12 are each independently an integer of 1 to 30, g9 is an integer of 1 to 400, and 15 is an integer of 1 to 200.