| abstract |
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: n n n n n n n n n n n n 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, n n n n n n n n n n n n n n n n wherein, in Chemical Formula 2, R 5 is alkyl group having 1 to 5 carbons. |