SYSTEMS, METHODS AND COMPUTER READABLE MEDIA FOR MODELING CELL PERFORMANCE FADE OF RECHARGEABLE ELECTROCHEMICAL DEVICES

• US 20110301931A1
• Filed: 06/03/2010
• Published: 12/08/2011
• Est. Priority Date: 06/03/2010
• Status: Active Grant

• Current Assignee: Battelle Energy Alliance LLC (Battelle Memorial Institute)
• Original Assignee: Battelle Energy Alliance LLC (Battelle Memorial Institute)
• Inventors: Gering, Kevin L.
• Granted Patent: US 8,521,497 B2
• Time in Patent Office: Days
• US Class Current: 703/13
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A system includes an electrochemical cell, monitoring hardware, and a computing system. The monitoring hardware periodically samples performance characteristics of the electrochemical cell. The computing system determines cell information from the performance characteristics of the electrochemical cell. The computing system also develops a mechanistic level model of the electrochemical cell to determine performance fade characteristics of the electrochemical cell and analyzing the mechanistic level model to estimate performance fade characteristics over aging of a similar electrochemical cell. The mechanistic level model uses first constant-current pulses applied to the electrochemical cell at a first aging period and at three or more current values bracketing a first exchange current density. The mechanistic level model also is based on second constant-current pulses applied to the electrochemical cell at a second aging period and at three or more current values bracketing the second exchange current density.

Claims

1. A method wherein at least one act of the method is performed by a processor, the method comprising:

developing a mechanistic level model of an electrochemical cell to determine performance fade characteristics of the electrochemical cell using;

first constant-current pulses applied to the electrochemical cell at a first aging period and at three or more current values bracketing a first exchange current density; and

second constant-current pulses applied to the electrochemical cell at a second aging period and at three or more current values bracketing the second exchange current density; and

analyzing the mechanistic level model to estimate performance fade characteristics over aging of a similar electrochemical cell.

2. The method of claim 1, wherein the performance fade characteristics comprise conductance fade.

3. The method of claim 1, wherein analyzing the mechanistic level model includes estimating for the similar electrochemical cell one or more of exchange current density, intrinsic charge transfer impedance, ohmic impedance, interfacial impedance contribution, total impedance, and electrode surface availability.

4. The method of claim 1, wherein:

the first constant-current pulses comprise current values of about one-half, two times, and four times the first exchange current density; and

the second constant-current pulses comprise current values of about one-half, two times, and four times the second exchange current density.

5. The method of claim 1, further comprising using a modified BV expression on ohmic-corrected data to determine the first exchange current density.

6. The method of claim 1, further comprising including a rate expression comprising a multiple sigmoid model in the mechanistic level model to predict future performance fade as a function of future time.

7. The method of claim 1, further comprising including a modified BV expression in the mechanistic level model to predict the performance fade characteristics at constant-current pulses different from the first constant-current pulses and the second constant-current pulses.

8. The method of claim 7, further comprising including a rate expression comprising a multiple sigmoid model in the mechanistic level model to predict future performance fade as a function of future time.

9. The method of claim 7, further comprising including a rate expression comprising a multiple sigmoid model in the mechanistic level model to predict future power characteristics using future conductance loss characteristics as a function of future time.

10. The method of claim 1, further comprising using constant-current pulses that emulate alternating current techniques for impedance determination by using pulse durations of the constant-current pulses corresponding to the inverse-square-root of frequency of the alternating current techniques.

11. A method wherein at least one act of the method is performed by a processor, the method comprising:

developing a mechanistic level model of an electrochemical cell to determine performance fade characteristics of the electrochemical cell using;

first constant-power pulses applied to the electrochemical cell at a first aging period and at three or more current values bracketing a first exchange current density; and

second constant-power pulses applied to the electrochemical cell at a second aging period and at three or more current values bracketing the second exchange current density; and

analyzing the mechanistic level model to estimate performance fade characteristics over aging of a similar electrochemical cell.

12. The method of claim 11, wherein the first constant-power pulses and the second constant-power pulses are determined iteratively by adjusting constant current pulses until the product of current and available voltage is within a predetermined tolerance of a first target power and a second target power, respectively.

13. A method, comprising:

developing a mechanistic level model of an electrochemical cell to determine performance fade characteristics of the electrochemical cell using;

first constant-current pulses applied to the electrochemical cell at a first aging period and at three or more current values bracketing a first exchange current density; and

second constant-current pulses applied to the electrochemical cell at a second aging period and at three or more current values bracketing the second exchange current density;

analyzing the mechanistic level model to estimate performance fade characteristics over aging of a similar electrochemical cell; and

modifying at least one of a discharge process for, a charge process for, and composition of, the electrochemical cell responsive to the analyzing the mechanistic level model.

14. The method of claim 13, wherein the performance fade characteristics comprise conductance fade.

15. The method of claim 13, wherein analyzing the mechanistic level model includes estimating for the similar electrochemical cell one or more of exchange current density, intrinsic charge transfer impedance, ohmic impedance, interfacial impedance contribution, total impedance, and electrode surface availability.

16. The method of claim 13, wherein:

the first constant-current pulses comprise current values of about one-half, two times, and four times the first exchange current density; and

the second constant-current pulses comprise current values of about one-half, two times, and four times the second exchange current density.

17. The method of claim 13, further comprising using a modified BV expression on ohmic-corrected data to determine the first exchange current density.

18. The method of claim 13, further comprising including a rate expression comprising a multiple sigmoid model in the mechanistic level model to predict future performance fade as a function of future time.

19. The method of claim 13, further comprising including a modified BV expression in the mechanistic level model to predict the performance fade characteristics at constant-current pulses different from the first constant-current pulses and the second constant-current pulses.

20. The method of claim 19, further comprising including a rate expression comprising a multiple sigmoid model in the mechanistic level model to predict future performance fade as a function of future time.

21. The method of claim 19, further comprising including a rate expression comprising a multiple sigmoid model in the mechanistic level model to predict future power characteristics using future conductance loss characteristics as a function of future time.

22. The method of claim 13, further comprising using constant-current pulses that emulate alternating current techniques for impedance determination by using pulse durations of the constant-current pulses corresponding to the inverse-square-root of frequency of the alternating current techniques.

23. A system, comprising:

an electrochemical cell;

monitoring hardware operably coupled to the electrochemical cell and configured for sampling cell characteristics of the electrochemical cell; and

a computing system operably coupled to the monitoring hardware and configured for;

developing a mechanistic level model of an electrochemical cell to determine performance fade characteristics of the electrochemical cell using the sampled cell characteristics for;

first constant-current pulses applied to the electrochemical cell at a first aging period and at three or more current values bracketing a first exchange current density; and

second constant-current pulses applied to the electrochemical cell at a second aging period and at three or more current values bracketing the second exchange current density; and

analyzing the mechanistic level model to estimate performance fade characteristics over aging of a similar electrochemical cell.

24. The system of claim 23, wherein the computing system comprises a memory for storing computing instructions and a processor operably coupled to the memory and configured for executing the computing instructions to carry out the acts of developing a mechanistic level model and analyzing the mechanistic level model.

25. The system of claim 23, wherein the computing system is further configured for providing:

the first constant-current pulses with current values of about one-half, two times, and four times the first exchange current density; and

the second constant-current pulses with current values of about one-half, two times, and four times the second exchange current density.

26. The system of claim 23, wherein the computing system is further configured for including a rate expression comprising a multiple sigmoid model in the mechanistic level model to predict future performance fade as a function of future time.

27. The system of claim 23, wherein the computing system is further configured for including a modified BV expression in the mechanistic level model to predict the performance fade characteristics at constant-current pulses different from the first constant-current pulses and the second constant-current pulses.

28. The system of claim 27, wherein the computing system is further configured for including a rate expression comprising a multiple sigmoid model in the mechanistic level model to predict future power characteristics using future conductance loss characteristics as a function of future time.

29. The system of claim 23, wherein the computing system is further configured for using constant-current pulses that emulate alternating current techniques for impedance determination by using pulse durations of the constant-current pulses corresponding to the inverse-square-root of frequency of the alternating current techniques.

30. A computer-readable medium including computer-executable instructions, which when executed on one or more processors, perform the acts comprising:

developing a mechanistic level model of an electrochemical cell to determine performance fade characteristics of the electrochemical cell using;

first constant-current pulses applied to the electrochemical cell at a first aging period and at three or more current values bracketing a first exchange current density; and

second constant-current pulses applied to the electrochemical cell at a second aging period and at three or more current values bracketing the second exchange current density; and

analyzing the mechanistic level model to estimate performance fade characteristics over aging of a similar electrochemical cell.

31. The computer-readable medium of claim 30, further comprising computer-executable instructions for instructing a charge circuit to provide:

the first constant-current pulses with current values of about one-half, two times, and four times the first exchange current density; and

the second constant-current pulses with current values of about one-half, two times, and four times the second exchange current density.

32. The computer-readable medium of claim 30, further comprising computer-executable instructions for including a rate expression comprising a multiple sigmoid model in the mechanistic level model to predict future performance fade as a function of future time.

33. The computer-readable medium of claim 30, further comprising computer-executable instructions for including a modified BV expression in the mechanistic level model to predict the performance fade characteristics at constant-current pulses different from the first constant-current pulses and the second constant-current pulses.

34. The computer-readable medium of claim 33, further comprising computer-executable instructions for including a rate expression comprising a multiple sigmoid model in the mechanistic level model to predict future power characteristics using future conductance loss characteristics as a function of future time.

35. The computer-readable medium of claim 30, further comprising computer-executable instructions for using constant-current pulses that emulate alternating current techniques for impedance determination by using pulse durations of the constant-current pulses corresponding to the inverse-square-root of frequency of the alternating current techniques.