DEEP-DISCHARGE CONDITIONING FOR LITHIUM-ION CELLS

• US 20150091530A1
• Filed: 09/30/2014
• Published: 04/02/2015
• Est. Priority Date: 09/30/2013
• Status: Abandoned Application

• Current Assignee: Navitas Systems, LLC
• Original Assignee: Navitas Systems, LLC
• Inventors: Zhang, Pu, Zhou, Hongxia, Wixom, Michael, Vu, Viet H., Hagans, Patrick L.
• Application Number:
  US14/501,521
• Publication Number:
  US 20150091530A1
• Time in Patent Office: Days
• US Class Current: 320/128
• 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 10/058 Construction or manufacture
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A process of reconditioning a lithium-ion cell is provided that unexpectedly improves cell capacity, reduces cold temperature impedance and increases cold cranking amps. The process involves a reconditioning step of holding a cell at a sub-discharge voltage for a recovery time. The sub-discharge voltage is 1.0V or less in many embodiments, optionally 0.0V. Holding this sub-discharge voltage for a recovery time of several hours will result in recovery of lost capacity that is in excess of that explainable by recovery of ions transferred to an anode overhang.

Claims

1. A process for reconditioning an electrochemical cell comprising:

holding a lithium-ion cell at a sub-discharge voltage of 2.0 Volts or less for a recovery time sufficient to show an increased capacity relative to an untreated cell.

2. The process of claim 1 wherein said capacity increase is 2 percent or greater.

3. The process of claim 1 wherein said sub-discharge voltage is 1.0 Volts or less.

4. The process of claim 1 wherein said sub-discharge voltage is 0 Volts.

5. The process of claim 1 wherein said recovery time is 1 hour or greater.

6. A process increasing cranking amperes of an electrochemical cell at a temperature less than 25 degrees Celsius comprising:

holding a lithium-ion cell at a sub-discharge voltage of 2.0 Volts or less for a recovery time sufficient to show increased cranking amperes of an electrochemical cell at 0 degrees Celsius or lower relative to an untreated cell.

7. The process of claim 6 wherein said cold cranking amperes is increased 1 percent or greater relative to said untreated cell.

8. The process of claim 6 wherein said reduced temperature is −

20 degrees Celsius or lower.

9. The process of claim 6 wherein said sub-discharge voltage is 1.0 Volts or less.

10. The process of claim 6 wherein said sub-discharge voltage is 0 Volts.

11. The process of claim 6 wherein said recovery time is 1 hour or greater.

12. The process of claim 6 wherein said sub-discharge voltage is less than 2.0 Volts and said recovery time is 24 hours or greater.

13. A process of increasing the cycle life of a lithium-ion cell comprising:

cycling a lithium-ion cell between a charge voltage and a discharge voltage for a first cycling period; and

holding said lithium-ion cell at a sub-discharge voltage of 2.0 Volts or less for a recovery time sufficient to show an increased capacity for 10 or more cycles.

14. The process of claim 13 wherein said increased capacity is 2 percent or greater.

15. The process of claim 13 wherein said first cycling period is from 50 to 250 cycles.

16. The process of claim 13 wherein said sub-discharge voltage is 1.0 Volt or less.

17. The process of claim 13 wherein said recovery time is from 24 to 120 hours.

18. The process of claim 13 further comprising cycling said cell for a second cycling period;

and

repeating said step of holding.

19. The process of claim 18 wherein said first cycling period and said second cycling period are each from 50 to 250 cycles.

20. The process of claim 18 wherein said both holding steps are at a voltage of 1.0 Volt or less.