| 摘要 |
Disclosed is a lithium secondary battery including a positive electrode, a negative electrode, a separator and a nonaqueous electrolyte, wherein the positive electrode includes Li a Ni x Mn y Co z O 2 (a+x+y+z=2, 0.9‰¤a‰¤1.1, 0‰¤x, 0‰¤y, 0‰¤z) as a positive electrode active material, and wherein the nonaqueous electrolyte includes (i) fluorinated cyclic carbonate expressed by Chemical Formula 1 below, (ii) propionate-based ester expressed by Chemical Formula 2 below, and (iii) non-halogenated carbonate, so that a mixture weight ratio (i : ii) thereof is 20:80 to 50:50:
wherein, in Chemical Formula 1, R 1 , R 2 , R 3 and R 4 are independently any one of F, H and methyl group, and at least one thereof is F,
wherein, in Chemical Formula 2, R 5 is alkyl group having 1 to 5 carbons. The lithium secondary battery may ensure stability of an electrolyte even though a loading amount of a positive electrode is increased to implement a high-voltage battery system, thereby allowing excellent cycle characteristics of the battery. In addition, it is possible to prevent degradation of the battery performance at high-temperature storage. |
