Diagnostic device for degradation of rechargeable Li-ion battery

• US 9,529,050 B2
• Filed: 03/15/2013
• Issued: 12/27/2016
• Est. Priority Date: 06/26/2012
• Status: Active Grant

• Current Assignee: IMV Corporation (John Wood Group PLC)
• Original Assignee: IMV Corporation (John Wood Group PLC)
• Inventors: Kawahira, Takao, Uchiyama, Yasuhiro, Kojima, Jumpei, Katsurai, Toru, Kawata, Koji, Kobayashi, Toshiyuki, Nishina, Tatsuo
• Primary Examiner(s): BOATENG, ALEXIS ASIEDUA
• Application Number:
  US13/836,085
• Publication Number:
  US 20130342212A1
• Time in Patent Office: 1,383 Days
• Field of Search: 324/426, 324/427, 324/429, 324/430, 324/433, 324/537, 324/434, 324/503, 324/697, 324/76.11, 320/134, 320/139, 320/107, 320/109, 320/108, 320/112, 320/117, 320/131, 320/132, 320/135, 320/150, 320/162, 702/63
• US Class Current: 1/1
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/385 Arrangements for measuring battery or accumulator variables for monitoring G01R31/382
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• 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: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A diagnostic device which can measure quickly and has simple circuit is provided. A charge/discharge circuit 2 supplies charge current to a rechargeable battery 10 and discharges the rechargeable battery 10. The charge/discharge circuit 2 also breaks charge current or discharge current of the rechargeable battery 10 in charging or discharging. A voltage measurement part 6 measures terminal voltage of the rechargeable battery 10 after breaking the charge or discharge current. Diagnostic means 8 judges whether the rechargeable battery 10 is deteriorated or not based on the measured voltages. Voltage change of deteriorated rechargeable battery 10 after breaking the charge or discharge current is more rapid than that of healthy rechargeable battery 10. The diagnostic means 8 can judge whether the rechargeable battery 10 is deteriorated or not based on such voltage change.

Claims

1. A diagnostic device that judges degradation of a rechargeable battery comprising:

means for breaking charge current of the rechargeable battery to change the terminals of the rechargeable battery to an open state, the rechargeable battery in a charging state connected to a charge circuit during charging of the rechargeable battery, or means for breaking discharge current of the rechargeable battery to change the terminals of the rechargeable battery to an open state, the rechargeable battery connected to a discharge circuit during discharging of the rechargeable battery;

a voltage measurement part which measures terminal voltage of the rechargeable battery for which charge current or discharge current is broken by the breaking means;

means for diagnosing degradation of the rechargeable battery based on the temporal change of terminal voltage measured by the voltage measurement part; and

a display connected to the diagnosing means that displays a judgement result,

wherein said diagnostic means judges whether the rechargeable battery is degraded or not based on a comparison of measured falling or rising speed of the terminal voltage of the rechargeable battery to be diagnosed immediately after the breaking and calculated falling or rising speed of the terminal voltage of a healthy rechargeable battery immediately after the breaking,

wherein said calculated falling or rising speed is calculated based on a thickness of a separator and a coefficient of ion diffusion of the healthy rechargeable battery.

2. The diagnostic device according to claim 1, wherein

said diagnostic means judges whether the rechargeable battery is degraded or not based on falling speed or rising speed of the terminal voltage immediately after the breaking.

3. A diagnostic device that judges degradation of a rechargeable battery comprising:

means for breaking charge current of the rechargeable battery to change the terminals of the rechargeable battery to an open state, the rechargeable battery in a charging state connected to a charge circuit during charging of the rechargeable battery, or means for breaking discharge current of the rechargeable battery to change the terminals of the rechargeable battery to an open state, the rechargeable battery connected to a discharge circuit during discharging of the rechargeable battery;

a voltage measurement part which measures terminal voltage of the rechargeable battery for which charge current or discharge current is broken by the breaking means;

means for diagnosing degradation of the rechargeable battery based on a temporal change of terminal voltage measured by the voltage measurement part; and

a display connected to the diagnosing means that displays a judgement result,

wherein said diagnostic means judges whether the rechargeable battery is degraded or not based on a time required for a gradient of the voltage drop immediately after the breaking to become predetermined smooth.

4. The diagnostic device according to claim 3, wherein

said diagnostic means judges whether the rechargeable battery is degraded or not based on a comparison of measured time required for gradient of the voltage drop of the rechargeable battery to be diagnosed immediately after the breaking to become predetermined smooth and calculated time required for gradient of the voltage drop of healthy rechargeable battery immediately after the breaking to become predetermined smooth,

wherein said calculated time required for a gradient of the voltage drop of the healthy rechargeable battery to become predetermined smooth is calculated based on thickness of a separator and a coefficient of ion diffusion of the healthy rechargeable battery.

5. A charge device for a rechargeable battery comprising:

a charge circuit which supplies charge current to the rechargeable battery;

means for breaking charge current of the rechargeable battery to change the terminals of the rechargeable battery to an open state, the rechargeable battery in a charging state connected to a charge circuit during charging of the rechargeable battery, or means for breaking discharge current of the rechargeable battery to change the terminals of the rechargeable battery to an open state, the rechargeable battery connected to a discharge circuit during discharging of the rechargeable battery;

a voltage measurement part which measures terminal voltage of the rechargeable battery in which charge current or discharge current is broken by the breaking means;

means for diagnosing degradation of the rechargeable battery based on the temporal change of terminal voltage measured by the voltage measurement part; and

a display connected to the diagnosing means that displays a judgement result,

wherein said diagnostic means judges whether the rechargeable battery is degraded or not based on a comparison of measured falling or rising speed of the terminal voltage of rechargeable battery to be diagnosed immediately after the breaking and calculated falling or rising speed of the terminal voltage of a healthy rechargeable battery immediately after the breaking,

wherein said calculated falling or rising speed is calculated based on a thickness of a separator and a coefficient of ion diffusion of the healthy rechargeable battery.

6. The charge device according to claim 5, wherein

said diagnostic means judges whether the rechargeable battery is degraded or not based on falling speed or rising speed of the terminal voltage immediately after the breaking.

7. A charge device for a rechargeable battery comprising:

a charge circuit which supplies charge current to the rechargeable batter;

means for breaking charge current of the rechargeable battery to change the terminals of the rechargeable battery to an open state, the rechargeable battery in a charging state connected to a charge circuit during charging of the rechargeable battery, or means for breaking discharge current of the rechargeable battery to change the terminals of the rechargeable battery to an open state, the rechargeable battery connected to a discharge circuit during discharging of the rechargeable battery;

a voltage measurement part which measures terminal voltage of the rechargeable battery in which charge current or discharge current is broken by the breaking means;

means for diagnosing degradation of the rechargeable battery based on a temporal change of terminal voltage measured by the voltage measurement part; and

a display connected to the diagnosing means that displays a judgement result,

wherein said diagnostic means judges whether the rechargeable battery is degraded or not based on time required for gradient of the voltage drop immediately after the breaking to become predetermined smooth.

8. The charge device according to claim 7, wherein

said diagnostic means judges whether the rechargeable battery is degraded or not based on comparison of measured time required for gradient of the voltage drop of rechargeable battery to be diagnosed immediately after the breaking to become predetermined smooth and calculated time required for gradient of the voltage drop of healthy rechargeable battery immediately after the breaking to become predetermined smooth,

wherein said calculated time required for gradient of the voltage drop of the healthy rechargeable battery to become predetermined smooth is calculated based on thickness of a separator and coefficient of ion diffusion of the healthy rechargeable battery.

9. A diagnostic method for judging degradation of a rechargeable battery, the method comprising the steps:

breaking charge current of the rechargeable battery to change the terminals of the rechargeable battery to an open state, the rechargeable battery in a charging state connected to a charge circuit during charging of the rechargeable battery, or breaking discharge current of the rechargeable battery to change the terminals of the rechargeable battery to an open state, the rechargeable battery connected to a discharge circuit during discharging of the rechargeable battery;

measuring terminal voltage of the rechargeable battery for which charge current or discharge current is broken;

diagnosing degradation of the rechargeable battery based on the temporal change of terminal voltage measured by the voltage measurement part; and

displaying a judgement result on a display,

wherein in said diagnostic step it is judged whether the rechargeable battery is degraded or not based on a comparison of measured falling or rising speed of the terminal voltage of the rechargeable battery to be diagnosed immediately after the breaking and calculated falling or rising speed of the terminal voltage of a healthy rechargeable battery immediately after the breaking,

wherein said calculated falling or rising speed is calculated based on a thickness of a separator and a coefficient of ion diffusion of the healthy rechargeable battery.

10. A diagnostic method for judging degradation of a rechargeable battery, the method comprising:

breaking charge current of the rechargeable battery to change the terminals of the rechargeable battery to an open state, the rechargeable battery in a charging state connected to a charge circuit during charging of the rechargeable battery, or breaking discharge current of the rechargeable battery to change the terminals of the rechargeable battery to an open state, the rechargeable battery connected to a discharge circuit during discharging of the rechargeable battery;

measuring terminal voltage of the rechargeable battery for which charge current or discharge current is broken by the breaking means;

diagnosing degradation of the rechargeable battery based on the temporal change of a terminal voltage measured by the voltage measurement part; and

displaying a judgement result on a display,

wherein in said diagnostic step it is judged whether the rechargeable battery is degraded or not based on a time required for a gradient of the voltage drop immediately after the breaking to become predetermined smooth.