Rechargeable battery electrode testing device

• US 6,177,799 B1
• Filed: 01/21/2000
• Issued: 01/23/2001
• Est. Priority Date: 01/21/2000
• Status: Expired due to Fees

• Current Assignee: Her Majesty The Queen In Right of Canada As Represented By The Minister of National Defence
• Original Assignee: Her Majesty The Queen In Right Of Canada (Government of Canada)
• Inventors: Martineau, Daniel, Wronski, Zbigniew S.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US09/489,334
• Time in Patent Office: 368 Days
• Field of Search: 324/425, 429/90
• US Class Current: 324/425
• CPC Class Codes: G01B 7/24 using change in magnetic properties
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: H01M 10/4285 Testing apparatus
• 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 6/50 Methods or arrangements for servicing or maintenance, e.g. for maintaining operating temperature 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: Y02E 60/10 Energy storage using batteries

Abstract

A testing device which measures minute changes in battery electrode thickness due to repeated charge/discharge cycles. The testing device uses a moving wall to detect changes in electrode dimensions, typically thickness. The moving wall is adjacent a surface of the electrode, and is connected a sensor that measures wall displacement induced by electrode dimensional changes. Also included in the testing device is a thermocouple that senses the temperature of the device, allowing the data sampling and processing means to correct for thermal expansion/contraction during operation. The testing device can be used during the battery cycling as it does not interfere with the charge/discharge/recharge process. The testing device can be used to measure either a single electrode, or a plurality of electrodes assembled into an electrode stack and incorporated either into a test cell or into a working battery.

Claims

1. A testing device for measuring dimensional changes in at least one fixed electrode within a rechargeable battery cell having a casing, the testing device comprising:

a moveable wall member adjacent to and maintained in contact with at least a portion of a surface of the at least one fixed electrode,

a wall member displacement detection means connected to the moveable wall,

a temperature sensing means for sensing the temperature of the device, and

a displacement measurement means outside the battery cell connected to the detection means.

2. A device as claimed in claim 1 wherein the at least one fixed electrode is carried by an interior surface of the battery cell casing.

3. A device as claimed in claim 1 wherein the displacement measurement means includes a computer based device constructed and arranged to process the data provided by the detection means.

4. A device as claimed in claim 3 wherein the computer based device is further constructed and arranged to process the data provided by the temperature sensing means.

5. A device as claimed in claim 4 wherein the computer based device is constructed and arranged to process the data provided by the temperature sensing means to provide a thermal expansion correction value to the data provided by the detection means.

6. A device as claimed in claim 4 wherein the temperature sensing means is a thermocouple.

7. A device as claimed in claim 5 wherein the temperature sensing means is a thermocouple.

8. A device as claimed in claim 1 wherein the displacement detection means comprises a linear voltage differential transformer.

9. A device as claimed in claim 1 wherein the measured dimension is the thickness of the at least one electrode.

10. A testing device for measuring changes in the thickness of either an electrode, or an electrode stack, for a battery undergoing repeated charge/discharge/recharge cycling comprising:

a container having a cavity containing the electrode, or the electrode stack, and a suitable electrolyte,

a first and a second pressure plate, each in contact with and supporting at least the periphery of each side of the electrode, or of the electrode stack,

a moveable wall member adjacent to and maintained in contact with at least a portion of one surface of the electrode, or of the electrode stack, and supported by the first pressure plate,

a temperature sensing means for sensing the temperature of the device,

a wall member displacement detection means connected to the moveable wall, and

a data processing means connected to both the detection means and the temperature sensing means.

11. A device as claimed in claim 10 wherein the displacement measurement means includes a suitable computer based device constructed and arranged to process the data provided by the detection means.

12. A device as claimed in claim 11 wherein the computer based device is further constructed and arranged to process the data provided by the temperature sensing means.

13. A device as claimed in claim 12 wherein the computer based device is constructed and arranged to process the data provided by the temperature sensing means to provide a thermal expansion correction value to the data provided by the detection means.

14. A device as claimed in claim 12 wherein the temperature sensing means is a thermocouple.

15. A device as claimed in claim 13 wherein the temperature sensing means is a thermocouple.

16. A device as claimed in claim 10 wherein the detection means is optical.

17. A device as claimed in claim 16 wherein the optical detection means comprises a laser.

18. A device as claimed in claim 10 wherein the detection means is magnetic.

19. A device as claimed in claim 18 wherein the magnetic detection means comprises a linear voltage differential transformer.

20. A device as claimed in claim 10 wherein the detection means is electrical.

21. A device as claimed in claim 20 wherein the electrical detection means comprises a variable capacitor associated with the moveable wall.

22. A device as claimed in claim 10 wherein the moveable wall is a flexible membrane.

23. A device as claimed in claim 10 wherein the moveable wall is a bellows structure.

24. A device as claimed in claim 10 further including means to monitor an electrolyte level within the cavity.

25. A device as claimed in claim 10 wherein the detection means is supported by the container outside the cavity.

26. A device as claimed in claim 25 wherein the supporting means together with the container comprises a monolithic block of material.

27. A device as claimed in claim 26 wherein the monolithic block of material is composed of polytetrafluoroethylene.