DEEP-DISCHARGE CONDITIONING FOR LITHIUM-ION CELLS

• US 20170117592A1
• Filed: 01/06/2017
• Published: 04/27/2017
• Est. Priority Date: 09/30/2013
• Status: Abandoned Application

• Current Assignee: Navitas Systems, LLC
• Original Assignee: Navitas Systems, LLC
• Inventors: Zhang, Pu, Vu, Viet H., Zhou, Hongxia, Hagans, Patrick L., Wixom, Michael
• Application Number:
  US15/400,063
• Publication Number:
  US 20170117592A1
• Time in Patent Office: Days
• 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:

cycling a lithium-ion cell to an operational discharge voltage 50 or more times;

cycling the lithium-ion cell to a sub-discharge voltage of less than 2.0 Volts;

holding the lithium-ion cell at the sub-discharge voltage for a recovery time sufficient to increase capacity of the lithium-ion cell.

2. The process of claim 1 wherein said capacity is increased 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:

cycling a lithium-ion cell to an operational discharge voltage 50 or more times;

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

7. The process of claim 6 wherein said cranking amperes is increased 1 percent or greater.

8. The process of claim 6 wherein said 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 cycle life of a lithium-ion cell comprising:

cycling a lithium-ion cell between a charge voltage and an operational discharge voltage for a first cycling period of 50 to 250 cycles; 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 capacity is increased 2 percent or greater.

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

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

17. The process of claim 13 further comprising cycling said lithium-ion cell for a second cycling period;

and

repeating said step of holding.

18. The process of claim 17 wherein said first cycling period and said second cycling period are each from 50 to 250 cycles.

19. The process of claim 17 wherein said holding steps are at a voltage of 1.0 Volt or less.