| 摘要 |
The present invention relates to a lithium secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode includes a positive electrode active material represented by Li_aNi_xMn_yCo_zO_2 (a+x+y+z=2, 0.9<=a<=1.1, 0<=x, 0<=y, 0<=z), and the non-aqueous electrolyte includes (i) fluorinated cyclic carbonate represented by chemical formula 1, (ii) propionate-based ester represented by chemical formula 2, and (iii) nonhalogenated carbonate, wherein the mixed weight ratio (i:ii) is 20:80 to 50:50. The lithium secondary battery of the present invention can prevent deterioration of the battery performance when being stored at a high temperature. |
