Non-aqueous electrolyte lithium secondary battery
View Patent ↗A lithium secondary battery has an anode, a cathode, a separator between the anode and the cathode and a non-aqueous electrolyte. The non-aqueous electrolyte includes a lithium salt; and a non-linear carbonate-based mixed organic solvent in which (a) a cyclic carbonate compound, and (b) a propionate-based compound are mixed at a volume ratio (a:b) in the range from about 10:90 to about 70:30, and optionally (c) a vinylene carbonate; and an inhibitor against a reaction between the anode and the propionate-based ester compound. The cathode has a current density in the range from about 3.5 to about 5.5 mA/cm 2 and a porosity in the range from about 18 to about 35%. This battery may be manufactured as a high-loading lithium secondary battery.
1. A lithium secondary battery comprising an anode made of carbon material capable of occluding or emitting lithium ions, a cathode made of lithium-containing oxide, a separator between the anode and the cathode, and a non-aqueous electrolyte,
wherein the non-aqueous electrolyte comprises:
a lithium salt;
a non-linear carbonate-based mixed organic solvent consisting of (a) a cyclic carbonate compound expressed by the following Chemical Formula 1 and (b) a propionate-based ester compound expressed by the following Chemical Formula 3, wherein (a) and (b) are mixed at a volume ratio (a:b) in the range from about 10:90 to about 70:30, and optionally (c) a vinylene carbonate expressed by the following Chemical Formula 2; and
an inhibitor against a reaction between the anode and the propionate-based ester compound in which the inhibitor is selected from the group consisting of a cyclic acid anhydride, a compound having a cyclic S═O group, and an acrylate-based compound, and an amount of the inhibitor against the reaction between the anode and the propionated-base ester compound is about 1 to 10 weight % based on the total weight of the non-aqueous electrolyte,
wherein the cathode has a current density in the range from 3.5 to 5.5 mA/cm 2 and a porosity in the range from 18 to 35%,
Chemical Formula 1
where R3 to R6 are independently any one selected from the group consisting of a hydrogen, fluorine, and an alkyl group having a carbon number of 1 to 4, respectively,
where R7 and R8 are independently a hydrogen or an alkyl group having a carbon number of 1 to 4 respectively, and
where R 1 is a CH 3 CH 2 group and R 2 is a linear or branched C 1-6 alkyl group, and R 1 and R 2 may be unsubstituted or substituted with at least one halogen, respectively.
2. The lithium secondary battery according to claim 1 , wherein the carbonate compound expressed by the Chemical Formula 1 is any one compound or a mixture of at least two compounds selected from the group consisting of ethylene carbonate, propylene carbonate, fluoroethylene carbonate and butylenes carbonate.
3. The lithium secondary battery according to claim 1 , wherein the vinylene carbonate compound expressed by Chemical Formula 2 is present.
4. The lithium secondary battery according to claim 1 , wherein the vinylene carbonate compound expressed by Chemical Formula 2 is not present.
5. The lithium secondary battery according to claim 1 , wherein the propionate-based ester compound expressed by the Chemical Formula 3 includes at least one compound selected from the group consisting of methyl propionate-based ester, ethyl propionate-based ester, propyl propionate-based ester, and butyl propionate-based ester.
6. The lithium secondary battery according to claim 1 , wherein the propionate-based ester compound is an ethyl propionate-based ester compound expressed by the following Chemical Formula 4,
where at least one hydrogen is capable of being substituted with fluorine.
7. The lithium secondary battery according to claim 6 , wherein the ethyl propionate-based compound expressed by the Chemical Formula 4 is any one compound or a mixture of at least two compounds selected from the group consisting of ethyl propionate, ethyl 3-fluoropropanoate, ethyl 3,3-difluoropropanoate, ethyl 3,3,3-trifluoropropanoate, 2-fluoroethyl propionate, 2,2-difluoroethyl propionate, 2,2,2-trifluoroethyl propionate, 2,2,2-trifluoroethyl 3-fluoropropanoate, 2,2,2-trifluoroethyl 3,3-difluoropropanoate, and 2,2,2-trifluoroethyl 3,3,3-trifluoropropanoate.
8. The lithium secondary battery according to claim 1 , wherein the lithium salt is any one compound or a mixture of at least two compound selected from the group consisting of LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiClO 4 , LiN(C 2 F 5 SO 2 ) 2 , LiN(CF 3 SO 2 ) 2 , CF 3 SO 3 Li and LiC(CF 3 SO 2 ) 3 .
9. A non-aqueous electrolyte comprising:
a lithium salt; and
a non-linear carbonate-based mixed organic solvent consisting of (a) a cyclic carbonate compound expressed by the following Chemical Formula 1 and (b) a propionate-based ester compound expressed by the following Chemical Formula 3 wherein (a) and (b) are mixed at a volume ratio (a:b) in the range from about 10:90 to about 70:30, and optionally (c) a vinylene carbonate expressed by the following Chemical Formula 2,
an inhibitor against a reaction between the anode and the propionate-based ester compound in which the inhibitor is selected from the group consisting of a cyclic acid anhydride, a compound having a cyclic S═O group, and an acrylate-based compound, and an amount of the inhibitor against the reaction between the anode and the propionated-base ester compound is about 1 to 10 weight % based on the total weight of the non-aqueous electrolyte,
where R3 to R6 are independently any one selected from the group consisting of a hydrogen, fluorine, and an alkyl group having a carbon number of 1 to 4, respectively,
where R7 and R8 are independently a hydrogen or an alkyl group having a carbon number of 1 to 4, respectively, and
where R 1 is a CH 3 CH 2 group and R 2 is a linear or branched C 1-6 alkyl group, and R 1 and R 2 may be unsubstituted or substituted with at least one halogen, respectively.
10. The non-aqueous electrolyte according to claim 9 , wherein the carbonate compound expressed by the Chemical Formula 1 is any one compound or a mixture of at least two compounds selected from the group consisting of ethylene carbonate, propylene carbonate, fluoroethylene carbonate and butylenes carbonate.
11. The non-aqueous electrolyte according to claim 9 , wherein the vinylene carbonate expressed by Chemical Formula 2 is present.
12. The non-aqueous electrolyte according to claim 9 , wherein the vinylene carbonate expressed by Chemical Formula 2 is not present.
13. The non-aqueous electrolyte according to claim 9 , wherein the propionate-based ester compound is an ethyl propionate-based ester compound expressed by the following Chemical Formula 4,
where at least one hydrogen is capable of being substituted with fluorine.
14. The non-aqueous electrolyte according to claim 13 , wherein the ethyl propionate-based compound expressed by the Chemical Formula 4 is any one compound or a mixture of at least two compounds selected from the group consisting of ethyl propionate, ethyl 3-fluoropropanoate, ethyl 3,3-difluoropropanoate, ethyl 3,3,3-trifluoropropanoate, 2-fluoroethyl propionate, 2,2-difluoroethyl propionate, 2,2,2-trifluoroethyl propionate, 2,2,2-trifluoroethyl 3-fluoropropanoate, 2,2,2-trifluoroethyl 3,3-difluoropropanoate, and 2,2,2-trifluoroethyl 3,3,3-trifluoropropanoate.