Device for assessing degree of degradation of secondary battery and assembled battery

Patent metadata

Field	Value
Publication number	US-2022146590-A1
Application number	US-202217585936-A
Country	US
Kind code	A1
Filing date	Jan 27, 2022
Priority date	Aug 1, 2019
Publication date	May 12, 2022
Grant date	—

Abstract

A degradation degree assessment device for a secondary battery is to assess a degree of degradation of a secondary battery and includes a battery characteristic acquisition unit, a capacity estimation unit, and an assessment unit. The battery characteristic acquisition unit acquires a battery characteristic relating to a voltage transition of the secondary battery in a predetermined voltage section. The assessment unit assesses the degree of degradation of the secondary battery based on the battery characteristic acquired by the battery characteristic acquisition unit or based on a battery characteristic-related value computed on the basis of the battery characteristic.

First claim

What is claimed is:

1 . A degradation degree assessment device for a secondary battery to assess a degree of degradation of the secondary battery, the degradation degree assessment device comprising:
a battery characteristic acquisition unit configured to acquire a battery characteristic, which relates to a transition of a battery state in a predetermined voltage section of the secondary battery; and an assessment unit configured to assess the degree of degradation of the secondary battery based on the battery characteristic, which is acquired by the battery characteristic acquisition unit, or based on a battery characteristic-related value, which is computed based on the battery characteristic, wherein the battery characteristic includes a discharge voltage characteristic, which is based on at least one of:
a voltage transition during discharge of the secondary battery to a predetermined discharge target voltage; or
a voltage transition after the secondary battery is discharged to the discharge target voltage and stops being discharged, and
the voltage transition is computed based on at least one of:
a section capacity of the secondary battery in the voltage section;
a rate of a voltage change of the secondary battery with respect to a capacity change of the secondary battery in the voltage section;
a rate of a voltage change of the secondary battery with respect to an elapsed time in the voltage section; or
a capacity ratio of the section capacity in the voltage section with respect to a total discharge capacity in a case of discharge to the discharge target voltage.

2 . The degradation degree assessment device for a secondary battery according to claim 1 , wherein
the battery characteristic includes a charge voltage characteristic, which is based on at least one of:
a voltage transition during charge of the secondary battery to a predetermined charge target voltage; or
a voltage transition after the secondary battery is charged to the charge target voltage and stops being charged.

3 . A degradation degree assessment device for a secondary battery to assess a degree of degradation of the secondary battery, the degradation degree assessment device comprising:
a battery characteristic acquisition unit configured to acquire a battery characteristic, which relates to a transition of a battery state in a predetermined voltage section of the secondary battery; and an assessment unit configured to assess the degree of degradation of the secondary battery based on the battery characteristic, which is acquired by the battery characteristic acquisition unit, or based on a battery characteristic-related value, which is computed based on the battery characteristic, the battery characteristic includes a charge voltage characteristic, which is based on at least one of:
a voltage transition during charge of the secondary battery to a predetermined charge target voltage; or
a voltage transition after the secondary battery is charged to the charge target voltage and stops being charged, and
the voltage transition is computed based on at least one of:
a section capacity of the secondary battery in the voltage section;
a rate of a voltage change of the secondary battery with respect to a capacity change of the secondary battery in the voltage section;
a rate of a voltage change of the secondary battery with respect to an elapsed time in the voltage section; or
a capacity ratio of the section capacity in the voltage section with respect to a total charge capacity in a case of charge to the charge target voltage.

4 . The degradation degree assessment device for a secondary battery according to claim 1 , wherein
the voltage section is a section in which a difference in the discharge voltage characteristic is significant depending on the degree of degradation of the secondary battery.

5 . The degradation degree assessment device for a secondary battery according to claim 1 , wherein
at least a part of the voltage section is included in a range from the discharge target voltage to a lower limit value of a voltage value of the secondary battery in a normal use range.

6 . The degradation degree assessment device for a secondary battery according to claim 3 , wherein
the voltage section is a section in which a difference in the charge voltage characteristic is significant depending on the degree of degradation of the secondary battery.

7 . The degradation degree assessment device for a secondary battery according to claim 3 , wherein
at least a part of the voltage section is included in a range from the charge target voltage to a lower limit value of a voltage value of the secondary battery in a normal use range.

8 . The degradation degree assessment device for a secondary battery according to claim 1 , further comprising:
an impedance characteristic acquisition unit configured to acquire an impedance characteristic, which relates to an impedance when the secondary battery is discharged or charged, wherein the assessment unit is configured to assess the degree of degradation based on the impedance characteristic, which is acquired by the impedance characteristic acquisition unit, or an impedance characteristic-related value, which is computed from the impedance characteristic, and based on the battery characteristic or the battery characteristic-related value.

9 . The degradation degree assessment device for a secondary battery according to claim 1 , further comprising:
an initial voltage acquisition unit configured to acquire an initial voltage, which is an open circuit voltage of the secondary battery when the battery characteristic acquisition unit starts acquiring the battery characteristic, wherein the assessment unit is configured to assess the degree of degradation based on the initial voltage, which is acquired by the initial voltage acquisition unit, or an initial voltage-related value, which is computed based on the initial voltage, and based on the battery characteristic or the battery characteristic-related value.

10 . The degradation degree assessment device for a secondary battery according to claim 1 , wherein
the battery characteristic acquisition unit includes a temperature detection unit configured to detect a temperature of the secondary battery, the battery characteristic includes a temperature characteristic, which is based on a temperature transition of the secondary battery in the voltage section, and the temperature transition is acquired by the temperature detection unit.

11 . The degradation degree assessment device for a secondary battery according to claim 1 , further comprising
an estimation unit configured to estimate, as the battery characteristic-related value, from the battery characteristic, at least one of:
a total capacity of the secondary battery;
a positive electrode capacity of the secondary battery;
a negative electrode capacity of the secondary battery;
an amount of deviation in a relative relationship between a negative electrode SOC and a positive electrode SOC of the secondary battery;
a variation in total capacity of a plurality of cells included in the secondary battery;
a battery resistance of the secondary battery;
a positive electrode resistance of the secondary battery; or
a negative electrode resistance of the secondary battery, wherein
the assessment unit is configured to assess the degree of degradation of the secondary battery based on a result of estimation by the estimation unit.

12 . An assembled battery comprising:
a plurality of secondary batteries, wherein the secondary batteries include a recycled product, and in the secondary batteries, a bat

Assignees

• Denso Corp

Inventors

• Asai Tomomi
• Yamamoto Nobuo
• Suzuki Hiroyasu
• Hayashi Katsuki
• MINABE Yuya

Classifications

• H02J7/84

  Control of state of health [SOH] · CPC title

• G01R31/396

  Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery · CPC title

• G01R31/389

  Measuring internal impedance, internal conductance or related variables · CPC title

• G01R31/374

  with means for correcting the measurement for temperature or ageing · CPC title

• G01R31/392 Primary

  Determining battery ageing or deterioration, e.g. state of health · CPC title