Lithium secondary battery comprising electrolyte

1. A lithium secondary battery, comprising:

an electrolyte comprising a non-aqueous organic solvent, a lithium salt, and an additive comprising a compound represented by Chemical Formula 1; and

a battery case in which the electrolyte is housed,

wherein the battery case has a shape with a width (W), a height (H), and a thickness (Th), and

when a maximum value among the width (W), the height (H), and the thickness (Th) is a and a minimum value among the width (W), the height (H), and the thickness (Th) is b, b/a is 0.01 or more:

and

wherein, in Chemical Formula 1, A is a substituted or unsubstituted aliphatic chain or (—C 2 H 4 —O—C 2 H 4 -)n, and n is an integer from 1 to 10.

2. The lithium secondary battery of claim 1 , wherein the lithium secondary battery is a pouch battery and b/a is 0.01 to 0.4.

3. The lithium secondary battery of claim 1 , wherein the lithium secondary battery is a prismatic battery and b/a is more than 0.1.

4. The lithium secondary battery of claim 1 , wherein the battery case is composed of a metal, a laminated sheet comprising a metal layer and a polymer layer, and/or steel.

5. The lithium secondary battery of claim 1 , wherein in Chemical Formula 1, A is a C2 to C20 hydrocarbon chain or (—C 2 H 4 —O—C 2 H 4 -)n, and n is an integer from 1 to 5.

6. The lithium secondary battery of claim 1 , wherein the compound represented by Chemical Formula 1 is a compound represented by Chemical Formula 1-1:

7. The lithium secondary battery of claim 1 , wherein the additive is 0.1 wt % to 10 wt % in amount based on a total amount of the electrolyte.

8. The lithium secondary battery of claim 7 , wherein the additive is 0.1 wt % to 5 wt % in amount based on the total amount of the electrolyte.

9. The lithium secondary battery of claim 1 , wherein the electrolyte further comprises an additional additive selected from fluoroethylene carbonate, vinylethylene carbonate, vinylene carbonate, succinonitrile, hexane tricyanide, lithiumtetrafluoroborate, propane sultone, and a combination thereof.

10. The lithium secondary battery of claim 9 , wherein the additional additive is 0.1 wt % to 20 wt % in amount based on a total amount of the electrolyte.

11. The lithium secondary battery of claim 1 , wherein the lithium salt is selected from LiPF 6 , LiSbF 6 , LiAsF 6 , LiN(SO 2 C 2 F 5 ) 2 , Li(CF 3 SO 2 ) 2 N, LiN(SO 3 C 2 F 5 ) 2 , LiC 4 F 9 SO 3 , LiClO 4 , LiAlO 2 , LiAlCl 4 , LiCl, LiI, LiB(C 2 O 4 ) 2 , LiDFOP, LiDFOB, LiPO 2 F 2 , and LiN(C x F 2x+1 SO 2 )(CyF 2y+1 SO 2 ), wherein x and y are each independently an integer from 0 to 20.

12. A method of manufacturing the lithium secondary battery of claim 1 , the method comprising:

mixing the non-aqueous organic solvent, the lithium salt, and the additive comprising the compound represented by Chemical Formula 1 to prepare the electrolyte; and

adding the electrolyte to the battery case.

13. A lithium secondary battery additive, comprising:

a compound represented by Chemical Formula 1,

wherein the compound is configured for a battery case having a shape with a width (W), a height (H), and a thickness (Th), and

when a maximum value among the width (W), the height (H), and the thickness (Th) is a and a minimum value among the width (W), the height (H), and the thickness (Th) is b, b/a is 0.01 or more:

and

wherein, in Chemical Formula 1, A is a substituted or unsubstituted aliphatic chain or (—C 2 H 4 —O—C 2 H 4 -)n, and n is an integer from 1 to 10.

14. A method of manufacturing the lithium secondary battery additive of claim 13 , the method comprising:

providing the compound represented by Chemical Formula 1,

wherein the additive is configured for the battery case having the shape with the width (W), the height (H), and the thickness (Th).