BACKGROUND

1. Technical Field

The present disclosure relates to a lithium secondary battery in which a lithium metal is used as an anode active material. More specifically, the present disclosure relates to improvement of a non-aqueous electrolyte in the lithium secondary battery.

2. Description of the Related Art

In the lithium secondary battery, a lithium metal is precipitated on the anode thereof during the charge. On the other hand, during the discharge, the lithium metal is dissolved in a non-aqueous electrolyte.

Patent Literature 1 discloses adding a nitrile compound to a non-aqueous electrolyte to improve a battery characteristic such as a cycle characteristic in a lithium ion battery. On the other hand, in the lithium secondary battery, a lithium metal is precipitated on the anode during the charge. Since the lithium metal has a high reduction ability, a side reaction occurs easily between the lithium metal and the non-aqueous electrolyte. As a result, the cycle characteristic is easily lowered. Patent Literature 2 discloses a lithium secondary battery comprising a non-aqueous electrolyte provided by dissolving a lithium salt in a solvent such as ethylene carbonate or diethyl carbonate.

CITATION LIST

Patent Literature

[Patent Literature 1] Japanese Patent Application Publication No. 2009-259472

[Patent Literature 2] Japanese Patent Application Publication No. 2001-243957

[Patent Literature 3] Japanese Patent Application Publication No. 2006-114388

[Patent Literature 4] Japanese Patent Application Publication No. 2017-059367

[Patent Literature 5] Japanese Patent Application Publication No. Hei 8-37024

SUMMARY

The present disclosure provides a lithium secondary battery excellent in a cycle characteristic.

The lithium secondary battery according to the present disclosure comprises:

a cathode;

an anode; and

a non-aqueous electrolyte having lithium ion conductivity,

wherein

a lithium metal is precipitated on a surface of the anode during charge of the lithium secondary battery;

the lithium metal is dissolved from the surface of the anode in the non-aqueous electrolyte during discharge of the lithium secondary battery;

the non-aqueous electrolyte contains a solvent and a lithium salt;

the solvent includes a fluorinated ether; and

the fluorinated ether has a fluorination ratio of more than 0% and not more than 60%.

The lithium secondary battery according to the present disclosure is excellent in a cycle characteristic.

