METHOD OF CHARGING LITHIUM METAL BATTERY

1 . A method of charging a lithium metal battery, the method comprising:

charging the lithium metal battery so that a constant voltage period and a first constant current period are separated from each other in time.

2 . The method of claim 1 , wherein

the lithium metal battery is charged so that a second constant current period occurs between the first constant current period and the constant voltage period, wherein a current value of the second constant current period is less than a current value of the first constant current period.

3 . The method of claim 2 , wherein

the lithium metal battery is charged so that a third constant current period occurs between the second constant current period and the constant voltage period, and

a current value of the third constant current period is less than that of the second constant current period.

4 . The method of claim 2 , wherein

when a voltage of the constant voltage period is referred to as V1, the second constant current period occurs at a voltage equal to or greater than approximately 0.80V1.

5 . The method of claim 3 , wherein

when a voltage of the constant voltage period is referred to as V1, the third constant current period occurs at a voltage equal to or greater than approximately 0.90V1.

6 . The method of claim 2 , wherein

the current value of the second constant current period is equal to or less than approximately 80 percent of the current value of the first constant current period.

7 . The method of claim 3 , wherein

the current value of the third constant current period is equal to or less than approximately 60 percent of the current value of the first constant current period.

8 . A method of charging a lithium metal battery, the method comprising:

reducing a charge current to be lower than a current of a constant current period before a constant voltage period occurs.

9 . The method of claim 8 , wherein

the reducing the charge current comprises discontinuously reducing the charge current until a point when the constant voltage period starts.

10 . The method of claim 8 , wherein

the reducing the charge current comprises reducing the charge current at least once.

11 . The method of claim 8 , wherein

the reducing the charge current comprises reducing the charge current at a voltage equal to or greater than approximately 80 percent of the voltage of the constant voltage period.

12 . A method of charging a lithium metal battery, in which a constant voltage period and a constant current period occur, the method comprising:

confirming occurrence of a voltage drop before the constant voltage period occurs;

measuring a degree of the voltage drop when the constant voltage period occurs;

comparing the degree of the voltage drop with a set value; and

reducing a charge current when the degree of the voltage drop is greater than the set value.

13 . The method of claim 12 , wherein

when the degree of the voltage drop is less than the set value, the reducing the charge current comprises maintaining the charge current without reducing the charge current.

14 . The method of claim 12 , wherein

when another voltage drop occurs after the charge current has been reduced, a subsequent process may be performed according to the processes which are performed after the voltage drop is occurred

15 . The method of claim 12 , wherein

the reducing the charge current comprises reducing the charge current to be equal to or less than approximately 80 percent of a current value of the constant voltage period.

16 . The method of claim 12 , wherein

the voltage drop occurs at a voltage equal to or greater than approximately 80 percent of the voltage of the constant voltage period.

17 . The method of claim 14 , wherein

another voltage drop occurs at a voltage equal to or greater than approximately 90 percent of the voltage of the constant voltage period.

18 . The method of claim 14 , wherein

when the reducing the charge current is repeated after the reducing the charge current, the charge current is reduced to be equal to or less than approximately 60 percent of a current value of the constant current period.