Gel polymer electrolyte and lithium secondary battery including the same

1. A gel polymer electrolyte comprising:

a matrix polymer; and

an electrolyte solution impregnated in the matrix polymer,

wherein the matrix polymer is formed in a three-dimensional network structure by polymerizing a first oligomer which is a compound represented by Formula 3:

wherein, in Formula 3,

R 1 and R 2 are each independently a fluorine-substituted or unsubstituted alkylene group having 1 to 4 carbon atoms,

R 3 is hydrogen, or an alkyl group having 1 to 6 carbon atoms,

R 4 is an alkylene group having 1 to 6 carbon atoms, —CH 2 —R 6 —CH 2 —, or CH 2 —R 7 —O—R 8 —CH 2 —, wherein R 6 , R 7 , and R 8 are alkylene groups having 1 to 5 carbon atoms in which at least one acrylate group is substituted,

R 5 is an alkylene group having 1 to 5 carbon atoms, or (CO—R 9 —O—) r —CO—NH—R 10 —NH—CO—O, wherein R 9 is an alkylene group having 1 to 10 carbon atoms, and R 10 is an aliphatic, alicyclic, or aromatic hydrocarbon group,

m1, n1, and o1 are the numbers of repeating units,

m1 is an integer of 1 to 10,

n1 is an integer of 1 to 10,

o1 is an integer of 1 to 500, and

r is an integer of 0 to 3.

2. The gel polymer electrolyte of claim 1 , wherein the first oligomer represented by Formula 3 comprises at least one compound selected from the group consisting of compounds represented by Formulae 3a to 3f:

wherein, in Formula 3a,

m2, n2, and o2 are the numbers of repeating units,

m2 is an integer of 1 to 10,

n2 is an integer of 1 to 10, and

o2 is an integer of 1 to 500,

wherein, in Formula 3b,

m3, n3, and o3 are the numbers of repeating units,

m3 is an integer of 1 to 10,

n3 is an integer of 1 to 10, and

o3 is an integer of 1 to 500,

wherein, in Formula 3c,

m4, n4, and o4 are the numbers of repeating units,

m4 is an integer of 1 to 10,

n4 is an integer of 1 to 10,

o4 is an integer of 1 to 500, and

r9 is an integer of 1 to 3,

wherein, in Formula 3d,

m5, n5, and o5 are the numbers of repeating units,

m5 is an integer of 1 to 10,

n5 is an integer of 1 to 10,

o5 is an integer of 1 to 500, and

r10 is an integer of 1 to 3,

wherein, in Formula 3e,

m6, n6, and o6 are the numbers of repeating units,

m6 is an integer of 1 to 10,

n6 is an integer of 1 to 10,

o6 is an integer of 1 to 500, and

r11 is an integer of 1 to 3,

wherein, in Formula 3f,

m7, n7, and o7 are the numbers of repeating units,

m7 is an integer of 1 to 10,

n7 is an integer of 1 to 10,

o7 is an integer of 1 to 500, and

r12 is an integer of 1 to 3.

3. The gel polymer electrolyte of claim 1 , wherein the first oligomer further comprises unit C which is derived from at least one selected from the group consisting of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, hexyl methacrylate, ethylhexyl acrylate, ethylhexyl methacrylate, 2,2,2-trifluoroethyl acrylate, 2,2,2-trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl acrylate, and 2,2,3,3-tetrafluoropropyl methacrylate.

4. The gel polymer electrolyte of claim 3 , wherein the unit C is included in an amount of 50 wt % or less based on a total amount of the first oligomer.

5. The gel polymer electrolyte of claim 1 , further comprising inorganic particles.

6. A composition for the gel polymer electrolyte of claim 1 , the composition comprising:

a lithium salt;

an electrolyte solution solvent;

a polymerization initiator; and

a first oligomer is a compound of Formula 3,

wherein, in Formula 3,

R 1 and R 2 are each independently a fluorine-substituted or unsubstituted alkylene group having 1 to 4 carbon atoms,

R 3 is hydrogen, or an alkyl group having 1 to 6 carbon atoms,

R 4 is an alkylene group having 1 to 6 carbon atoms, —CH 2 —R 6 —CH 2 —, or —CH 2 —R 7 —O—R 8 —CH 2 —, wherein R 6 , R 7 , and R 8 are alkylene groups having 1 to 5 carbon atoms in which at least one acrylate group is substituted,

R 5 is an alkylene group having 1 to 5 carbon atoms, or —(CO—R 9 —O—) r —CO—NH—R 10 —NH—CO—O, wherein R 9 is an alkylene group having 1 to 10 carbon atoms, and R 10 is an aliphatic, alicyclic, or aromatic hydrocarbon group,

m1, n1, and o1 are the numbers of repeating units,

m1 is an integer of 1 to 10,

n1 is an integer of 1 to 10,

o1 is an integer of 1 to 500, and

r is an integer of 0 to 3.

7. A lithium secondary battery comprising:

a positive electrode and a negative electrode;

a separator disposed between the positive electrode and the negative electrode; and

the gel polymer electrolyte of claim 1 disposed between the positive electrode, the negative electrode, and the separator.