Polymer electrolyte for secondary battery and secondary battery including the same

1. A polymer electrolyte for a secondary battery, the polymer electrolyte comprising a polymer which includes at least one repeating unit of repeating unit A represented by Formula 1 and repeating unit B represented by Formula 2:

wherein, in Formula 1 or 2,

R and R 5 are carbon (C) or sulfur (S),

R 1 and R 6 are

wherein R 9 is —C(CF 3 ) 2 —,

R 2 and R 7 are

R 3 is —S(CF 2 ) 2 SO 3 − Li + ,

R 4 is

wherein R 10 is —C(CF 3 ) 2 —,

R 8 is

o and o′ are 1 or 2,

p, p′, q, q′, r, and s are 0 or 1,

each of n, m, n′, and m′ is the number of moles of repeating units,

a ratio of n:m is in a range of 95:5 to 5:95, and

a ratio of n′:m′ is in a range of 95:5 to 5:95.

2. The polymer electrolyte for a secondary battery of claim 1 , wherein, in Formula 1, the ratio of n:m is in a range of 40:60 to 60:40, and

in Formula 2, the ratio of n′:m′ is in a range of 40:60 to 60:40.

3. The polymer electrolyte for a secondary battery of claim 1 , wherein, in Formula 1, the ratio of n:m is 50:50, and

in Formula 2, the ratio of n′:m′ is 50:50.

4. The polymer electrolyte for a secondary battery of claim 1 , wherein the polymer including the repeating unit represented by Formula 1 or the polymer including the repeating unit represented by Formula 2 has a weight-average molecular weight (Mw) of 5,000 g/mol to 2,000,000 g/mol.

5. The polymer electrolyte for a secondary battery of claim 1 , wherein the polymer including the repeating unit represented by Formula 1 or the polymer including the repeating unit represented by Formula 2 has a weight-average molecular weight (Mw) of 500,000 g/mol to 1,000,000 g/mol.

6. The polymer electrolyte for a secondary battery of claim 1 , wherein the repeating unit represented by Formula 1 comprises at least one selected from the group consisting of those represented by Formulae 1a to 1c:

wherein, in Formula 1a,

n1 and m1 are the number of moles of repeating units, and

a ratio of n1:m1 is in a range of 95:5 to 5:95,

wherein, in Formula 1b,

n2 and m2 are the number of moles of repeating units, and

a ratio of n2:m2 is in a range of 95:5 to 5:95,

wherein, in Formula 1c,

n3 and m3 are the number of moles of repeating units, and

a ratio of n3:m3 is in a range of 95:5 to 5:95.

7. The polymer electrolyte for a secondary battery of claim 1 , wherein the repeating unit represented by Formula 2 comprises one represented by Formula 2a:

wherein, in Formula 2a,

n′1 and m′1 are the number of moles of repeating units, and

a ratio of n′1:m′1 is in a range of 95:5 to 5:95.

8. The polymer electrolyte for a secondary battery of claim 1 , wherein the polymer electrolyte is a free-standing solid polymer electrolyte.

9. The polymer electrolyte for a secondary battery of claim 1 , wherein the polymer electrolyte is a gel polymer electrolyte further including a lithium salt-containing electrolyte solution.

10. The polymer electrolyte for a secondary battery of claim 9 , wherein the gel polymer electrolyte further comprises an ionic liquid.

11. The polymer electrolyte for a secondary battery of claim 10 , wherein the ionic liquid comprises at least one selected from the group consisting of diethylmethylammonium trifluoromethanesulfonate, dimethylpropylammonium trifluoromethanesulfonate, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methyl pyrrolidinium bis(trifluoromethanesulfonyl)imide, and methyl propylpiperidinium trifluoromethanesulfonylimide.

12. The polymer electrolyte for a secondary battery of claim 10 , wherein the ionic liquid is included in an amount of 0.01 wt % to 50 wt % based on a total weight of the polymer electrolyte.

13. A lithium secondary battery comprising:

a positive electrode;

a negative electrode; and

a polymer electrolyte formed on at least one surface of the positive electrode and the negative electrode,

wherein the polymer electrolyte comprises the polymer electrolyte for a secondary battery of claim 1 .

14. The lithium secondary battery of claim 13 , further comprising a separator,

wherein the polymer electrolyte is formed on at least one surface of the positive electrode, the negative electrode, and the separator.