Method of evaluating power storage device, method of manufacturing power storage device, and test system

Patent metadata

Field	Value
Publication number	US-11650260-B2
Application number	US-202117224340-A
Country	US
Kind code	B2
Filing date	Apr 7, 2021
Priority date	Nov 29, 2017
Publication date	May 16, 2023
Grant date	May 16, 2023

Abstract

A method of evaluating a power storage device includes at least [a] to [f] below. [a] A power storage device is prepared. [b] A charge level of the power storage device is adjusted to produce a first potential difference between a positive electrode and a negative electrode. [c] The positive electrode or the negative electrode is selected as a reference electrode. [d] After the charge level is adjusted, an operation to insert a conductive rod-shaped member into a stack portion along a direction of stack of the positive electrode and the negative electrode is performed while a second potential difference between the reference electrode and the rod-shaped member is measured. [e] The rod-shaped member is stopped. [f] The power storage device is evaluated based on a state of the power storage device after the rod-shaped member is stopped.

First claim

What is claimed is:

1. A method of evaluating a secondary lithium-ion cell comprising:
preparing a secondary lithium-ion cell including at least a casing and an electrode assembly, the electrode assembly being accommodated in the casing, the electrode assembly including a positive electrode and a negative electrode, at least one positive electrode and at least one negative electrode being alternately stacked to form a stack portion in the electrode assembly;
adjusting a state of charge of the secondary lithium-ion cell to 100% to produce a first potential difference between the positive electrode and the negative electrode;
selecting the positive electrode or the negative electrode as a reference electrode;
performing an operation to insert a conductive rod-shaped member into the stack portion along a direction of stack of the positive electrode and the negative electrode while a second potential difference between the reference electrode and the rod-shaped member is measured after the state of charge is adjusted;
stopping the rod-shaped member; and
evaluating the secondary lithium-ion cell by observing a state of the secondary lithium-ion cell over one hour after the rod-shaped member is stopped,
when an electrode with which the rod-shaped member comes in contact first in the stack portion is different from the reference electrode, the operation to insert the rod-shaped member being controlled to stop the rod-shaped member when decrease in absolute value of the second potential difference is detected at least once, and
when the electrode with which the rod-shaped member comes in contact first in the stack portion is identical to the reference electrode, the operation to insert the rod-shaped member being controlled to stop the rod-shaped member when increase in the absolute value of the second potential difference is detected at least once, wherein
the secondary lithium-ion cell is prismatic or pouch cell,
the operation to insert the rod-shaped member is performed in a temperature environment of 10° C. to 50° C.,
the rod-shaped member includes a metal nail containing iron,
the rod-shaped member has a diameter of 1 mm to 3 mm,
an angle at the tip end of the rod-shaped member is not smaller than twenty degrees and not greater than ninety degrees,
a rate of insertion of the rod-shaped member is not lower than 0.001 mm/second and not higher than 0.1 mm/second.

2. The method of evaluating a secondary lithium-ion cell according to claim 1 , wherein
the rod-shaped member is inserted into the stack portion from outside of the casing.

3. The method of evaluating a secondary lithium-ion cell according to claim 1 , wherein
the positive electrode is selected as the reference electrode.

4. The method of evaluating a secondary lithium-ion cell according to claim 1 , wherein
the electrode with which the rod-shaped member comes in contact first in the stack portion is different from the reference electrode.

5. The method of evaluating a secondary lithium-ion cell according to claim 4 , the method further comprising evaluating the secondary lithium-ion cell by detecting increase in the absolute value of the second potential difference while the rod-shaped member remains stopped after the rod-shaped member is stopped.

6. The method of evaluating a secondary lithium-ion cell according to claim 5 , the method further comprising evaluating the secondary lithium-ion cell based on a time period elapsed since a time point of stop of the rod-shaped member until a time point of increase in the absolute value of the second potential difference.

7. The method of evaluating a secondary lithium-ion cell according to claim 4 , wherein
the operation to insert the rod-shaped member is controlled to stop the rod-shaped member when decrease in the absolute value of the second potential difference is detected a plurality of times.

8. The method of evaluating a secondary lithium-ion cell according to claim 1 , wherein
the electrode with which the rod-shaped member comes in contact first in the stack portion is identical to the reference electrode.

9. The method of evaluating a secondary lithium-ion cell according to claim 8 , the method further comprising evaluating the secondary lithium-ion cell by detecting decrease in the absolute value of the second potential difference while the rod-shaped member remains stopped after the rod-shaped member is stopped.

10. The method of evaluating a secondary lithium-ion cell according to claim 9 , the method further comprising evaluating the secondary lithium-ion cell based on a time period elapsed since a time point of stop of the rod-shaped member until a time point of decrease in the absolute value of the second potential difference.

11. The method of evaluating a secondary lithium-ion cell according to claim 8 , wherein
the operation to insert the rod-shaped member is controlled to stop the rod-shaped member when increase in the absolute value of the second potential difference is detected a plurality of times.

12. A method of manufacturing a secondary lithium-ion cell comprising at least:
manufacturing a plurality of the secondary lithium-ion cells; and
evaluating one or more of the plurality of the secondary lithium-ion cells by the method of evaluating a secondary lithium-ion cell according to claim 1 .

13. A test system for evaluating a secondary lithium-ion cell, the secondary lithium-ion cell including at least a casing and an electrode assembly, the casing having a prismatic shape or a flat shape, the electrode assembly being accommodated in the casing, the electrode assembly including a positive electrode and a negative electrode, at least one positive electrode and at least one negative electrode being alternately stacked to form a stack portion in the electrode assembly, the test system comprising:
a drive device;
a voltage measurement device; and
a control device,
the drive device being configured to perform an operation to insert a conductive rod-shaped member into the stack portion along a direction of stack of the positive electrode and the negative electrode,
the voltage measurement device being configured to measure a potential difference between a reference electrode and the rod-shaped member,
the positive electrode or the negative electrode being selected as the reference electrode,
the control device being configured to carry out at least one of first control and second control,
in the first control, when an electrode with which the rod-shaped member comes in contact first in the stack portion is different from the reference electrode, the operation to insert the rod-shaped member by the drive device being controlled to stop the rod-shaped member when decrease in absolute value of the potential difference is detected at least once, and
in the second control, when the electrode with which the rod-shaped member comes in contact first in the stack portion is identical to the reference electrode, the operation to insert the rod-shaped member by the drive device being controlled to stop the rod-shaped member when increase in the absolute value of the potential difference is detected at least once, wherein
the secondary lithium-ion cell is prismatic or pouch cell,
the operation to insert the rod-shaped member is performed in a temperature environment of 10° C. to 50° C.,
the rod-shaped member includes a metal nail containing iron,
the rod-shaped member has a diameter of 1 mm to 3 mm,
an angle at the tip end of the rod-shaped member is not smaller than twenty degrees and not greater than ninety degrees,
a rate of insertion of the rod-shaped member is not lower than 0.001 mm/second and not h

Assignees

• Toyota Motor Co Ltd

Inventors

• Miyazawa Kensaku
• Hamasaki Shinichi
• Ishihara Yuya
• Kaneko Tetsuya

Classifications

• H02J7/875

  Charging or discharging for charge maintenance, battery initiation or rejuvenation · CPC title

• G01R31/385

  Arrangements for measuring battery or accumulator variables (for monitoring G01R31/382) · CPC title

• G01R31/3865 Primary

  related to manufacture, e.g. testing after manufacture · CPC title

• G01R31/52 Primary

  Testing for short-circuits, leakage current or ground faults · CPC title

• H01M50/572

  Means for preventing undesired use or discharge · CPC title