Battery Phase Meter to Determine Internal Temperatures of Lithium-Ion Rechargeable Cells Under Charge and Discharge

• US 20120155507A1
• Filed: 10/18/2011
• Published: 06/21/2012
• Est. Priority Date: 10/18/2010
• Status: Active Grant

• Current Assignee: Johns Hopkins University
• Original Assignee: Johns Hopkins University
• Inventors: Srinivasan, Rengaswamy, Carkhuff, Bliss G., Phillips, Terry E., Butler, Michael H., Walker, Jeremy D., Uy, Oscar M., Baisden, Andrew C.
• Granted Patent: US 8,961,004 B2
• Time in Patent Office: Days
• US Class Current: 374/45
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• 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 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 10/486 for measuring temperature
• CPC Class Codes: H01M 2200/10 Temperature sensitive devices
• CPC Class Codes: H01M 50/574 Devices or arrangements for the interruption of current
• CPC Class Codes: H01M 50/581 in response to temperature
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Methods and systems to determine an internal temperature of a rechargeable lithium-ion cell based on a phase shift of the cell. Internal cell temperature may be determined with respect to an internal anode temperature and/or an internal cathode temperature. Internal anode temperature may be determined based on a phase shift of a frequency within a range of approximately 40 Hertz (Hz) to 500 Hz. Internal cathode temperature may be determined based on a phase shift of a frequency of up to approximately 30 Hz. A temperature sensor as disclosed herein may be powered by a monitored cell with relatively little impact on cell charge, may be electrically coupled to cell but housed physically separate from the cell, and/or may monitor multiple cells in a multiplex fashion. A rate of change in phase shift may be used to initiate pre-emptive action, without determining corresponding temperatures.

Claims

1. A method of measuring an internal temperature of a lithium-ion rechargeable cell, comprising:

applying an alternating signal to the cell to generate a phase-shifted alternating signal at the cell;

detecting the phase shift as a phase difference between a frequency of the applied alternating signal and a frequency of the phase-shifted alternating signal; and

determining the internal temperature of the cell based on the phase difference;

wherein the applying includes one or more of applying an alternating current to generate a phase phase-shifted alternating voltage, and applying an alternating voltage to generate a phase phase-shifted alternating current.

2. The method of claim 1, wherein the frequency of the applied alternating signal is within a range of up to approximately 1000 Hertz (Hz).

3. The method of claim 2, wherein the frequency of the applied alternating signal is within a range of approximately 40 Hz to 100 Hz, and wherein the determining includes determining an internal anode temperature of the cell based on the phase difference.

4. The method of claim 2, wherein the frequency of the applied alternating signal is within a range of approximately 10 Hz to 20 Hz, and wherein the determining includes determining an internal cathode temperature of the cell based on the phase difference.

5. The method of claim 1, wherein:

the applying includes applying first and second alternating signals to the cell to generate corresponding first and second phase-shifted alternating signals at the cell;

the detecting includes detecting a first phase difference between a frequency of the first applied alternating signal and a frequency of the first phase-shifted alternating signal, and detecting a second phase difference between a frequency of the second applied alternating signal and a frequency of the second phase-shifted signal;

the frequency of the first applied alternating signal is within a range of approximately 40 Hertz (Hz) to 100 Hz;

the frequency of the second applied alternating signal is within a range of approximately 10 Hz to 20 Hz; and

the determining includes determining an internal anode temperature of the cell based on the first phase difference, and determining an internal cathode temperature of the cell based on the second phase difference.

6. The method of claim 1, further including:

isolating the cell from one or more of a charging circuit and a discharging circuit under one or more of the following conditions,

the internal temperature of the cell exceeds a threshold temperature, and

a rate of increase of the internal temperature of the cell meets or exceeds a threshold rate.

7. The method of claim 1, further including:

performing the applying, the detecting, and the determining under one or more of the following conditions,

while the cell is charging, and

while the cell is discharging to a load.

8. The method of claim 1, wherein the determining includes retrieving an indication of the temperature from a look-up table based on the phase difference.

9. A system to measure an internal temperature of a lithium-ion rechargeable cell, comprising:

an alternating signal source to apply an alternating signal to the cell to generate a phase-shifted alternating signal at the cell;

a phase meter to detect the phase-shift as a phase difference between a frequency of the applied alternating signal and a frequency of the phase-shifted alternating signal; and

a phase-to-temperature converter to determine the internal temperature of the cell based on the phase difference;

wherein the alternating signal source includes one or more of an alternating current source to generate a phase-shifted alternating voltage, and an alternating voltage source to generate a phase-shifted alternating current.

10. The system of claim 9, wherein the alternating signal source is implemented to apply the alternating signal within a frequency range of up to approximately 1000 Hertz (Hz).

11. The system of claim 10, wherein the alternating signal source is implemented to apply the alternating signal within a frequency range of approximately 40 Hz to 100 Hz, and wherein the phase-to-temperature converter is implemented to determine an internal anode temperature of the cell based on the phase difference.

12. The system of claim 10, wherein the alternating signal source is implemented to apply the alternating signal with in a frequency range of approximately 10 Hz to 20 Hz, and wherein the phase-to-temperature converter is implemented to determine an internal cathode temperature of the cell based on the phase difference.

13. The system of claim 9, wherein:

the alternating signal source includes first and second alternating signal sources to apply corresponding first and second alternating signals to the cell to generate corresponding first and second phase-shifted alternating signals at the cell;

the phase meter is implemented to detect a first phase difference between a frequency of the first applied alternating signal and a frequency of the first phase-shifted alternating signal, and to detect a second phase difference between a frequency of the second applied alternating signal and a frequency of the second phase-shifted alternating signal;

the first alternating signal source is implemented to generate the first alternating signal within a frequency range of approximately 30 Hertz (Hz) to 100 Hz;

the second alternating signal source is implemented to generate the second alternating signal within a frequency range of approximately 10 Hertz (Hz) to 20 Hz; and

the phase-to-temperature converter is implemented to determine an internal anode temperature of the cell based on the first phase difference, and an internal cathode temperature of the cell based on the second phase difference.

14. The system of claim 9, wherein the phase-to-temperature converter includes a look-up table of phase-to-temperature correlations.

15. The system of claim 9, further including:

a control system to isolate the cell from one or more of a charging circuit and a discharging circuit under one or more of the following conditions,

when the internal temperature of the cell exceeds a threshold temperature, and

when a rate of increase of the internal temperature of the cell meets or exceeds a threshold rate.

16. A method of correlating a phase delay of a rechargeable lithium-ion cell with an internal temperature of the cell, comprising:

applying an alternating signal to the cell when the internal temperature of the cell is at a first temperature to generate a phase-delayed alternating signal at the cell;

detecting a phase difference between a frequency of the applied alternating signal and a frequency of the phase-shifted alternating signal;

repeating the applying and the detecting for one or more additional internal temperatures of the cell;

correlating the phase differences with the temperatures; and

recording the correlations in a tangible medium;

wherein the applying includes one or more of applying an alternating current to generate a phase phase-shifted alternating voltage, and applying an alternating voltage to generate a phase phase-shifted alternating current.

17. The method of claim 16, further including:

performing the applying and the detecting under one or more of the following conditions,

while the cell is charging, and

while the cell is discharging to a load.

18. The method of claim 16, wherein the correlating includes:

correlating the phase differences with internal temperatures of the cell, for temperatures within a range of approximately −

80°

C. to 100°

C.

19. The method of claim 16, wherein the frequency of the applied alternating signal is within a range of up to approximately 1000 Hertz (Hz).

20. The method of claim 19, wherein the frequency of the applied alternating signal is within a range of approximately 40 Hz to 100 Hz, and wherein the correlating includes correlating the phase differences with internal anode temperatures of the cell.

21. The method of claim 19, wherein the frequency of the applied alternating signal is within a range of approximately 10 Hz to 20 Hz, and wherein the correlating includes correlating the phase differences with internal cathode temperatures of the cell.

22. The method of claim 19, wherein:

the applying includes applying first and second alternating signals to the cell to generate corresponding first and second phase-shifted alternating signals at the cell;

the detecting includes detecting a first phase difference between a frequency of the first applied alternating signal and a frequency of the first phase-shifted alternating signal, and detecting a second phase difference between a frequency of the second applied alternating signal and a frequency of the second phase-shifted signal;

wherein the frequency of the first applied alternating signal is within a range of approximately 40 Hertz (Hz) to 100 Hz, and the frequency of the second applied alternating signal is within a range of approximately 10 Hz to 20 Hz; and

the correlating includes correlating the first phase differences with internal anode temperatures of the cell, and correlating the second phase differences with internal cathode temperatures of the cell.

23. A method of identifying a condition prior to thermal runaway in a lithium-ion cell, comprising:

applying an alternating signal to the cell to generate a phase-shifted alternating signal at the cell;

detecting the phase shift as a phase difference between a frequency of the applied alternating signal and a frequency of the phase-shifted alternating signal;

wherein the applying and the detecting are performed continuously or periodically; and

initiating a pre-emptive action when a rate of change of the phase-difference meets or exceeds a threshold rate.

24. The method of claim 23, wherein the initiating includes:

isolating the cell from one or more of a charging circuit and a discharging circuit.