LIFETIME ESTIMATING METHOD AND DETERIORATION SUPPRESSING METHOD FOR RECHARGEABLE LITHIUM BATTERY, LIFETIME ESTIMATING APPARATUS, DETERIORATION SUPPRESSOR, AND BATTERY PACK AND CHARGER USING THE SAME

• US 20100264929A1
• Filed: 12/11/2008
• Published: 10/21/2010
• Est. Priority Date: 12/13/2007
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Ugaji, Masaya, Yamamoto, Taisuke
• Granted Patent: US 8,373,419 B2
• Time in Patent Office: Days
• US Class Current: 324/426
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/42 Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells H01M10/60 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

In a lifetime estimating method for a rechargeable lithium battery, the open circuit voltages of the rechargeable lithium battery after discharging for at least two different charge/discharge cycle numbers are detected while charge/discharge cycles go on. Next, at least the two of the voltage values are plotted for respective cycle numbers, and a circular arc passing the plotted points is drawn. Furthermore, the lifetime of the rechargeable lithium battery is estimated based on a size of the circular arc. The progression of deterioration can be suppressed by controlling the charge and discharge of the rechargeable lithium battery based on the lifetime estimation.

Claims

1. A method of estimating lifetime of a rechargeable lithium battery, the rechargeable lithium battery comprising:

a positive electrode having a positive active material capable of absorbing and releasing lithium ions;

a negative electrode having a negative active material containing at least one of elements, silicon and tin; and

an electrolyte having lithium-ion conductivity and disposed between the positive electrode and the negative electrode,

the method comprising;

A) detecting open circuit voltages of the rechargeable lithium battery after discharging for at least two different charge/discharge cycle numbers while charge/discharge cycles go on;

B) plotting at least the two of the voltage values detected in step A with respect to respective cycle numbers;

C) drawing a circular arc passing the plotted points of step B; and

D) estimating lifetime of the rechargeable lithium battery based on a size of the circular arc drawn in step C.

2. The method of estimating the lifetime of the rechargeable lithium battery according to claim 1, further comprising

E) predicting one of available cycle number and time based on the lifetime estimated in step D and a use history of the rechargeable lithium battery at the estimation time.

3. The method of estimating the lifetime of the rechargeable lithium battery according to claim 1, further comprising:

F) reducing charge/discharge capacity by controlling charge of the rechargeable lithium battery based on the lifetime estimated in step D so as to suppress deterioration of the rechargeable lithium battery; and

G) storing the charge/discharge capacity reduced in step F, and again estimating lifetime of the rechargeable lithium battery after execution of step F by further performing step A through step D.

4. The method of estimating the lifetime of the rechargeable lithium battery according to claim 1, further comprising:

F) reducing charge/discharge capacity by controlling discharge of the rechargeable lithium battery based on the lifetime estimated in step D so as to suppress deterioration of the rechargeable lithium battery; and

G) storing the charge/discharge capacity reduced in step F, and again estimating lifetime of the rechargeable lithium battery after execution of step F by further performing step A through step D.

5. The method of estimating the lifetime of the rechargeable lithium battery according to claim 1, wherein voltage is detected in step A in a state where residual capacity of the rechargeable lithium battery is 10% or lower of that in a last full charge period.

6. A method of suppressing deterioration of a rechargeable lithium battery, the rechargeable lithium battery comprising:

a positive electrode having a positive active material capable of absorbing and releasing lithium ions;

a negative electrode having a negative active material containing at least one of elements, silicon and tin; and

an electrolyte having lithium-ion conductivity and disposed between the positive electrode and the negative electrode,

the method comprising;

A) detecting open circuit voltages of the rechargeable lithium battery after discharging for at least two different charge/discharge cycle numbers while charge/discharge cycles go on;

B) plotting at least the two of the voltage values detected in step A with respect to respective cycle numbers;

C) drawing a circular arc passing the plotted points of step B;

D) estimating lifetime of the rechargeable lithium battery based on a size of the circular arc drawn in step C; and

F) controlling charge of the rechargeable lithium battery based on the lifetime estimated in step D.

7. The method of suppressing the deterioration of the rechargeable lithium battery according to claim 6, wherein

charge time is shortened in step F.

8. The method of suppressing the deterioration of the rechargeable lithium battery according to claim 6, wherein

charge cutoff voltage is varied in step F.

9. The method of suppressing the deterioration of the rechargeable lithium battery according to claim 6, wherein

voltage is detected in step A in a state where residual capacity of the rechargeable lithium battery is 10% or lower of that in a last full charge period.

10. A method of suppressing deterioration of a rechargeable lithium battery, the rechargeable lithium battery comprising:

a positive electrode having a positive active material capable of absorbing and releasing lithium ions;

a negative electrode having a negative active material containing at least one of elements, silicon and tin; and

an electrolyte having lithium-ion conductivity and disposed between the positive electrode and the negative electrode,

the method comprising;

A) detecting open circuit voltages of the rechargeable lithium battery after discharging for at least two different charge/discharge cycle numbers while charge/discharge cycles go on;

B) plotting at least the two of the voltage values detected in step A with respect to respective cycle numbers;

C) drawing a circular arc passing the plotted points of step B;

D) estimating lifetime of the rechargeable lithium battery based on a size of the circular arc drawn in step C; and

F) controlling discharge of the rechargeable lithium battery based on the lifetime estimated in step D.

11. The method of suppressing the deterioration of the rechargeable lithium battery according to claim 10, wherein

discharge time is shortened in step F.

12. The method of suppressing the deterioration of the rechargeable lithium battery according to claim 10, wherein

discharge cutoff voltage is varied in step F.

13. The method of suppressing the deterioration of the rechargeable lithium battery according to claim 10, wherein

voltage is detected in step A in a state where residual capacity of the rechargeable lithium battery is 10% or lower of that in a last full charge period.

14. A lifetime estimating apparatus for a rechargeable lithium battery, the rechargeable lithium battery comprising:

a positive electrode having a positive active material capable of absorbing and releasing lithium ions;

a negative electrode having a negative active material containing at least one of elements, silicon and tin; and

an electrolyte having lithium-ion conductivity and disposed between the positive electrode and the negative electrode,

the apparatus comprising;

a detecting section configured to detect open circuit voltages of the rechargeable lithium battery after discharging for at least two different charge/discharge cycle numbers while charge/discharge cycles go on;

a plot section configured to plot at least the two of the detected voltage values for respective cycle numbers;

an estimating section configured to draw a circular arc passing the plotted points plotted by the plot section; and

a determining section configured to estimate lifetime of the rechargeable lithium battery based on a size of the circular arc.

15. The lifetime estimating apparatus for the rechargeable lithium battery according to claim 14, wherein

the determining section is capable of predicting one of available cycle number and time based on the lifetime estimated by the determining section and a use history of the rechargeable lithium battery at the estimation time.

16. The lifetime estimating apparatus for the rechargeable lithium battery according to claim 14, further comprising:

a control section configured to reduce charge/discharge capacity by controlling charge of the rechargeable lithium battery based on the lifetime estimated by the determining section, and suppressing deterioration of the rechargeable lithium battery,

wherein the determining section stores the reduced charge/discharge capacity, and again estimates lifetime of the rechargeable lithium battery after reduction of charge/discharge capacity.

17. The lifetime estimating apparatus for the rechargeable lithium battery according to claim 14, further comprising:

a control section configured to reduce charge/discharge capacity by controlling discharge of the rechargeable lithium battery based on the lifetime estimated by the determining section, and suppressing deterioration of the rechargeable lithium battery,

wherein the determining section stores the reduced charge/discharge capacity, and again estimates lifetime of the rechargeable lithium battery after reduction of the charge/discharge capacity.

18. The lifetime estimating apparatus for the rechargeable lithium battery according to claim 14, wherein

the detecting section detects voltage in a state where residual capacity of the rechargeable lithium battery is 10% or lower of that in a last full charge period.

19. A deterioration suppressor for a rechargeable lithium battery, the rechargeable lithium battery comprising:

a positive electrode having a positive active material capable of absorbing and releasing lithium ions;

a negative electrode having a negative active material containing at least one of elements, silicon and tin; and

an electrolyte having lithium-ion conductivity and disposed between the positive electrode and the negative electrode,

the deterioration suppressor comprising;

a detecting section configured to detect open circuit voltages of the rechargeable lithium battery after discharging for at least two different charge/discharge cycle numbers while charge/discharge cycles go on;

a plot section configured to plot at least the two of the detected voltage values for respective cycle numbers;

an estimating section configured to draw a circular arc passing the plotted points plotted by the plot section; and

a determining section configured to estimate lifetime of the rechargeable lithium battery based on a size of the circular arc; and

a control section configured to control charge of the rechargeable lithium battery based on the lifetime estimated by the determining section.

20. The deterioration suppressor for the rechargeable lithium battery according to claim 19, wherein

the detecting section detects voltage in a state where residual capacity of the rechargeable lithium battery is 10% or lower of that in a last full charge period.

21. A battery pack comprising:

a rechargeable lithium battery including;

a positive electrode having a positive active material capable of absorbing and releasing lithium ions;

a negative electrode having a negative active material containing at least one of elements, silicon and tin; and

an electrolyte having lithium-ion conductivity and disposed between the positive electrode and the negative electrode,

a detecting section configured to detect open circuit voltages of the rechargeable lithium battery after discharging for at least two different charge/discharge cycle numbers while charge/discharge cycles go on;

a plot section configured to plot at least the two of the detected voltage values for respective cycle numbers;

an estimating section configured to draw a circular arc passing the plotted points plotted by the plot section;

a determining section configured to estimate lifetime of the rechargeable lithium battery based on a size of the circular arc; and

a control section configured to control charge of the rechargeable lithium battery based on the lifetime estimated by the determining section.

22. The battery pack according to claim 21, wherein

the detecting section detects voltage in a state where residual capacity of the rechargeable lithium battery is 10% or lower of that in a last full charge period.

23. A charger for a rechargeable lithium battery, the rechargeable lithium battery comprising:

a positive electrode having a positive active material capable of absorbing and releasing lithium ions;

a negative electrode having a negative active material containing at least one of elements, silicon and tin; and

an electrolyte having lithium-ion conductivity and disposed between the positive electrode and the negative electrode,

the charger comprising;

a deterioration suppressor including;

a detecting section configured to detect open circuit voltages of the rechargeable lithium battery after discharging for at least two different charge/discharge cycle numbers while charge/discharge cycles go on;

a plot section configured to plot at least the two of the detected voltage values for respective cycle numbers;

an estimating section configured to draw a circular arc passing the plotted points plotted by the plot section;

a determining section configured to estimate lifetime of the rechargeable lithium battery based on a size of the circular arc;

a control section configured to control charge of the rechargeable lithium battery based on the lifetime estimated by the determining section; and

a charging section configured to charge the rechargeable lithium battery.

24. The charger according to claim 23, wherein

the detecting section detects voltage in a state where residual capacity of the rechargeable lithium battery is 10% or lower of that in a last full charge period.

25. A deterioration suppressor for a rechargeable lithium battery, the rechargeable lithium battery comprising:

a positive electrode having a positive active material capable of absorbing and releasing lithium ions;

a negative electrode having a negative active material containing at least one of elements, silicon and tin; and

an electrolyte having lithium-ion conductivity and disposed between the positive electrode and the negative electrode,

the deterioration suppressor comprising;

a detecting section configured to detect open circuit voltages of the rechargeable lithium battery after discharging for at least two different charge/discharge cycle numbers while charge/discharge cycles go on;

a plot section configured to plot at least the two of the detected voltage values for respective cycle numbers;

an estimating section configured to draw a circular arc passing the plotted points plotted by the plot section;

a determining section configured to estimate lifetime of the rechargeable lithium battery based on a size of the circular arc; and

a control section configured to control discharge of the rechargeable lithium battery based on the lifetime estimated by the determining section.

26. The deterioration suppressor of the rechargeable lithium battery according to claim 25, wherein

the detecting section detects voltage in a state where residual capacity of the rechargeable lithium battery is 10% or lower of that in a last full charge period.

27. A battery pack comprising:

a rechargeable lithium battery including;

a positive electrode having a positive active material capable of absorbing and releasing lithium ions;

a negative electrode having a negative active material containing at least one of elements, silicon and tin; and

an electrolyte having lithium-ion conductivity and disposed between the positive electrode and the negative electrode,

a detecting section configured to detect open circuit voltages of the rechargeable lithium battery after discharging for at least two different charge/discharge cycle numbers while charge/discharge cycles go on;

a plot section configured to plot at least the two of the detected voltage values for respective cycle numbers;

an estimating section configured to draw a circular arc passing the plotted points plotted by the plot section;

a determining section configured to estimate lifetime of the rechargeable lithium battery based on a size of the circular arc; and

a control section configured to control discharge of the rechargeable lithium battery based on the lifetime estimated by the determining section.

28. The battery pack according to claim 27, wherein the detecting section detects voltage in a state where residual capacity of the rechargeable lithium battery is 10% or lower of that in a last full charge period.