Method for charging secondary battery using multiple charging sections
A method of charging a secondary battery, including first, second and third charging sections in which a CC-charging performed as first, second, and third Crate (C1, C2, C3), respectively, is supplied until the voltage of the secondary battery reaches a respective first, second and third charging cutoff voltage (V1), (V2), (V3) and a CV-charging is performed as the respective charging C-rate gradually decreases in response to reaching the respective charging cutoff voltage (V1), (V2), (V3), wherein the charging cutoff voltage satisfies the V1=n−(0.25˜0.15), V2 n−(0.2˜0.1), and V3=n (here, ‘n’ is an electric potential at the full charge of the secondary battery), and V1<V2<V3.
1. A method of charging a secondary battery, including charging sections by preset C-rates, and performing a constant current-constant voltage (CC-CV) charging in each of the charging sections,
wherein the charging sections comprise:
a first charging section in which a CC-charging is performed as a first C-rate (C1) is supplied until the voltage of the secondary battery reaches a first charging cutoff voltage (V1), and a CV-charging is performed as a charging C-rate gradually decreases in response to reaching the first charging cutoff voltage (V1);
a second charging section in which a CC-charging is performed as a second C-rate (C2) is supplied until the voltage of the secondary battery reaches a second charging cutoff voltage (V2), and a CV-charging is performed as the charging C-rate gradually decreases in response to reaching the second charging cutoff voltage (V2); and
a third charging section in which a CC-charging is performed as a third C-rate (C3) is supplied until the voltage of the secondary battery reaches a third charging cutoff voltage (V3), and a CV-charging is performed as the charging C-rate gradually decreases in response to reaching the third charging cutoff voltage (V3),
wherein the charging cutoff voltage satisfies the V1=n−(0.25˜0.15), V2=n−(0.2˜0.1), and V3=n (here, ‘n’ is an electric potential at the full charge of the secondary battery), and V1<V2<V3, and
wherein C1=3.3C, C2=2.5C and C3=0.8C.
2. The method of claim 1 , wherein the charge C-rate having reached the charge cutoff voltage at each charge section gradually decreases to the preset C-rate of the next charge section.
3. The method of claim 1 , wherein C1, C2 and C3 are set on the basis of a target C-rate (Ct).
4. The method of claim 3 , wherein the target C-rate Ct is to correspond to the constant current-constant voltage (CC-CV) charge and is determined by a loading amount of a negative electrode of the secondary battery.
5. The method of claim 4 , wherein the target C-rate (Ct) is in inverse proportion to the amount of loading of the negative electrode.
6. The method of claim 5 , wherein the target C-rate (Ct) is in inverse proportion to the amount of loading of the negative electrode, exponentially.
7. The method of claim 1 , wherein the secondary battery is a lithium ion battery having embedded therein an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode in a battery case in a state of being impregnated with an electrolytic solution.
8. The method of claim 7 , wherein the negative electrode comprises graphite carbon as a negative electrode active material.
9. The method of claim 7 , wherein a potential of the negative electrode during one time charge of the secondary battery does not reach a lithium dendrite growth potential in the charging sections.
10. The method of claim 1 , wherein a difference between a maximum value and a minimum value of a negative electrode flat section during the charging of the secondary battery is maintained at less than 0.15V.
11. A method of charging a secondary battery, including charging sections by preset C-rates, and performing a constant current-constant voltage (CC-CV) charging in each of the charging sections,
wherein the charging sections comprise:
a first charging section in which a CC-charging is performed as a first C-rate (C1) is supplied until the voltage of the secondary battery reaches a first charging cutoff voltage (V1), and a CV-charging is performed as a charging C-rate gradually decreases in response to reaching the first charging cutoff voltage (V1);
a second charging section in which a CC-charging is performed as a second C-rate (C2) is supplied until the voltage of the secondary battery reaches a second charging cutoff voltage (V2), and a CV-charging is performed as the charging C-rate gradually decreases in response to reaching the second charging cutoff voltage (V2); and
a third charging section in which a CC-charging is performed as a third C-rate (C3) is supplied until the voltage of the secondary battery reaches a third charging cutoff voltage (V3), and a CV-charging is performed as the charging C-rate gradually decreases in response to reaching the third charging cutoff voltage (V3),
wherein the charging cutoff voltage satisfies the V1=n−(0.25˜0.15), V2=n−(0.2˜0.1), and V3=n (here, ‘n’ is an electric potential at the full charge of the secondary battery), and V1<V2<V3, and
wherein C1=2.0C, C2=1.5C and C3=0.5C.
12. The method of claim 11 , wherein the charge C-rate having reached the charge cutoff voltage at each charge section gradually decreases to the preset C-rate of the next charge section.
13. The method of claim 11 , wherein C1, C2 and C3 are set on the basis of a target C-rate.
14. The method of claim 13 , wherein the target C-rate Ct is set to correspond to the constant current-constant voltage (CC-CV) charge and is determined by a loading amount of a negative electrode of the secondary battery.
15. The method of claim 14 , wherein the target Crate (Ct) is in inverse proportion to the amount of loading of the negative electrode.
16. The method of claim 15 , wherein the target Crate (Ct) is in inverse proportion to the amount of loading of the negative electrode, exponentially.
17. The method of claim 11 , wherein the secondary battery is a lithium ion battery having embedded therein an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode in a battery case in a state of being impregnated with an electrolytic solution.
18. The method of claim 17 , wherein the negative electrode comprises graphite carbon as a negative electrode active material.
19. The method of claim 17 , wherein a potential of the negative electrode during one time charge of the secondary battery does not reach a lithium dendrite growth potential in the charging sections.
20. The method of claim 1 , wherein a difference between a maximum value and a minimum value of a negative electrode flat section during the charging of the secondary battery is maintained at less than 0.15V.