Nonaqueous electrolyte solution and lithium secondary battery using same
View Patent ↗Disclosed is a lithium secondary battery which is excellent in battery characteristics such as long-term cycle characteristics, capacity and shelf life characteristics. Also disclosed is a nonaqueous electrolyte solution which can be used for such a lithium secondary battery. Specifically disclosed is a nonaqueous electrolyte solution for lithium secondary batteries obtained by dissolving an electrolyte salt in a nonaqueous solvent which is characterized by containing 0.01-10% by weight of a carboxylate compound represented by the general formula (I) below and 0.01-10% by weight or 0.01-10% by volume of a vinylene carbonate and/or 1,3-propane sultone. Also disclosed is a lithium secondary battery using such a nonaqueous electrolyte solution. (In the formula, R 2 represents a hydrogen atom or COOR 3 group, R 1 and R 3 respectively represent an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group or a phenyl group, and X represents an alkynylene group or an alkenylene group.)
1. A nonaqueous electrolyte solution for lithium secondary batteries, in which an electrolyte salt is dissolved in a nonaqueous solvent, the nonaqueous electrolyte solution comprising 0.01 to 10% by weight of a carboxylate compound represented by the formula (I) shown below, and 0.01 to 10% by weight or 0.01 to 10% by volume of at least one selected from the group consisting of a vinylene carbonate and 1,3-propane sultone:
wherein R 1 represents a C 1 to C 12 alkyl group which may be branched, a C 3 to C 8 cycloalkyl group, a C 2 to C 12 alkenyl group which may be branched, a C 2 to C 12 alkynyl group which may be branched, or an unsubstituted or substituted phenyl group, R 2 represents a hydrogen atom or a COOR 3 group where R 3 represents a C 1 to C 12 alkyl group which may be branched, a C 3 to C 8 cycloalkyl group, a C 2 to C 12 alkenyl group which may be branched, a C 2 to C 12 alkynyl group which may be branched, or an unsubstituted or substituted phenyl group, and X represents a C 2 to C 4 alkynylene group.
2. A nonaqueous electrolyte solution as defined in claim 1 , wherein the carboxylate compound represented by the above general formula (I) is at least one member selected from the group consisting of a dialkyl acetylenedicarboxylate having C 1 to C 3 alkyl groups, dialkyl 3-hexynedioate having C 1 to C 3 alkyl groups, and a dialkyl 2,4-hexadiynedioate having C 1 to C 3 alkyl groups.
3. The nonaqueous electrolyte solution of claim 2 , wherein the carboxylate compound represented by formula (I) is at least one member selected from the group consisting of dimethyl acetylenedicarboxylate, diethyl acetylenedicarboxylate, diethyl 3-hexynedioate and dimethyl 2,4-hexadiynedioate.
4. A nonaqueous electrolyte solution as defined in claim 1 , wherein the carboxylate compound represented by the general formula (I) is present in an amount of 0.05 to 5% by weight and at least one of the vinylene carbonate and the 1,3-propane sultone is present in an amount of 0.02 to 9% by volume.
5. A nonaqueous electrolyte solution as defined in claim 1 , wherein the nonaqueous solvent contains at least one selected from the group consisting of cyclic ethylene carbonate and cyclic propylene carbonate.
6. A nonaqueous electrolyte solution as defined in claim 1 , wherein the nonaqueous solvent contains at least one member selected from the group consisting of methyl ethyl carbonate, dimethyl carbonate and diethyl carbonate.
7. The nonaqueous electrolyte solution of claim 1 , wherein the carboxylate compound represented by formula (I) is at least one member selected from the group consisting of dimethyl acetylenedicarboxylate, diethyl acetylenedicarboxylate, diethyl 3-hexynedioate and dimethyl 2,4-hexadiynedioate.
8. The nonaqueous electrolyte solution of claim 1 , comprising both a vinylene carbonate and 1,3-propane sultone.
9. The nonaqueous electrolyte solution of claim 1 , wherein R 1 is a C 1 to C 12 alkyl group, R 2 is a group COOR 3 where R 3 is a C 1 to C 12 alkyl group.
10. The nonaqueous electrolyte solution of claim 1 , wherein the electrolyte salt is LiPF 6 .
11. The nonaqueous electrolyte solution of claim 1 , wherein the electrolyte salt comprises LiBF 4 .
12. The nonaqueous electrolyte solution of claim 1 , wherein R 1 represents a C 1 to C 12 alkyl group which may be branched, a C 3 to C 8 cycloalkyl group, a C 2 to C 12 alkynyl group which may be branched, or an unsubstituted or substituted phenyl group, R 2 represents a hydrogen atom or a COOR 3 group where R 3 represents a C 1 to C 12 alkyl group which may be branched, a C 3 to C 8 cycloalkyl group, a C 2 to C 12 alkynyl group which may be branched, or an unsubstituted or substituted phenyl group, and X represents a C 2 to C 4 alkynylene group.
13. A lithium secondary battery comprising a positive electrode, a negative electrode, and a nonaqueous electrolyte solution which includes an electrolyte salt dissolved in a nonaqueous solvent, the positive electrode including a lithium compound oxide-containing material, the negative electrode including a material which can occlude and release lithium, and the nonaqueous electrolyte solution comprising 0.01 to 10% by weight of a carboxylate compound represented by the formula (I) shown below, and 0.01 to 10% by weight or 0.01 to 10% by volume of at least one selected from the group consisting of vinylene carbonate and 1,3-propane sultone:
wherein R 1 represents a C 1 to C 12 alkyl group which may be branched, a C 3 to C 8 cycloalkyl group, a C 2 to C 12 alkenyl group which may be branched, a C 2 to C 12 alkynyl group which may be branched, or an unsubstituted or substituted phenyl group, R 2 represents a hydrogen atom or a COOR 3 group where R 3 represents a C 1 to C 12 alkyl group which may be branched, a C 3 to C 8 cycloalkyl group, a C 2 to C 12 alkenyl group which may be branched, a C 2 to C 12 alkynyl group which may be branched, or an unsubstituted or substituted phenyl group, and X represents a C 2 to C 4 alkynylene group.
14. The lithium secondary battery of claim 13 , wherein the positive electrode comprises one or more lithium compound oxides containing at least one member selected from the group consisting of cobalt, manganese and nickel as a positive electrode active material.
15. The lithium secondary battery of claim 13 , wherein the negative electrode comprises at least one member selected from the group consisting of a thermally decomposed carbon material, a coke, a graphite, a fired organic polymer body and a carbon fiber as a negative electrode active material.
16. The lithium secondary battery of claim 13 , comprising both a vinylene carbonate and 1,3-propane sultone.
17. The lithium secondary battery of claim 13 , wherein R 1 is a C 1 to C 12 alkyl group, R 2 is a group COOR 3 , where R 3 is a C 1 to C 12 alkyl group.
18. The lithium secondary battery of claim 13 , wherein the electrolyte salt is LiPF 6 .
19. The lithium secondary battery of claim 13 , wherein the electrolyte salt comprises LiBF 4 .
20. The lithium secondary battery of claim 13 , wherein R 1 represents a C 1 to C 12 alkyl group which may be branched, a C 3 to C 8 cycloalkyl group, a C 2 to C 12 alkynyl group which may be branched, or an unsubstituted or substituted phenyl group, R 2 represents a hydrogen atom or a COOR 3 group where R 3 represents a C 1 to C 12 alkyl group which may be branched, a C 3 to C 8 cycloalkyl group, a C 2 to C 12 alkynyl group which may be branched, or an unsubstituted or substituted phenyl group, and X represents a C 2 to C 4 alkynylene group.