Apparatus and method of estimating state of lithium ion battery

Patent metadata

Field	Value
Publication number	US-2018340984-A1
Application number	US-201815958723-A
Country	US
Kind code	A1
Filing date	Apr 20, 2018
Priority date	May 26, 2017
Publication date	Nov 29, 2018
Grant date	—

Abstract

A control device calculates an amount of increase ΔAm in freezing temperature measurement value Am from an initial freezing temperature Δ 0 and calculates an amount of lowering in capacity corresponding to the amount of increase ΔAm in freezing temperature as an amount of lowering in capacity ΔBx due to deterioration of a material. The control device calculates an amount of lowering in capacity measurement value Bm from an initial capacity B 0 as a whole amount of lowering in capacity ΔBm and calculates a material deterioration ratio X by using ΔBx and ΔBm. The control device calculates a value resulting from subtraction of ΔBx from ΔBm as an amount of lowering in capacity ΔBy due to precipitation of Li and calculates an Li precipitation deterioration ratio Y by using ΔBy and ΔBm.

First claim

What is claimed is:

1 . An apparatus which estimates a state of a lithium ion battery, the apparatus comprising:
a first calculator configured to calculate a measurement value of a freezing temperature of an electrolyte of the lithium ion battery; a second calculator configured to calculate a measurement value of a capacity of the lithium ion battery; and an estimator configured to estimate a state of the lithium ion battery, the estimator calculating at least one of a material deterioration ratio representing a ratio of an amount of lowering in capacity due to deterioration of a material to a whole amount of lowering in capacity of the lithium ion battery and a precipitation deterioration ratio representing a ratio of an amount of lowering in capacity due to precipitation of lithium to the whole amount of lowering in capacity, by using the measurement value of the freezing temperature and the measurement value of the capacity.

2 . The apparatus according to claim 1 , further comprising a storage which stores in advance information representing correspondence between the capacity and the freezing temperature when lithium is not precipitated but the material has deteriorated, wherein
the estimator is configured to calculate a first amount of lowering in capacity corresponding to a difference between the measurement value of the freezing temperature and an initial freezing temperature by referring to the information stored in the storage, calculate a difference between the measurement value of the capacity and an initial capacity as a second amount of lowering in capacity, and calculate a value resulting from division of the first amount of lowering in capacity by the second amount of lowering in capacity as the material deterioration ratio.

3 . The apparatus according to claim 2 , wherein
the estimator is configured to calculate a value resulting from division of a third amount of lowering in capacity by the second amount of lowering in capacity as the precipitation deterioration ratio, the third amount of lowering in capacity resulting from subtraction of the first amount of lowering in capacity from the second amount of lowering in capacity.

4 . The apparatus according to claim 1 , wherein
the first calculator is configured to sequentially measure an impedance of the lithium ion battery with a temperature of the lithium ion battery being increased and lowered, specify a temperature at which hysteresis of a resistance of the lithium ion battery exhibited with variation in temperature starts to appear by using a result of measurement of the impedance, and define the temperature at which hysteresis of the resistance starts to appear as the measurement value of the freezing temperature.

5 . A method of estimating a state of a lithium ion battery comprising:
calculating a measurement value of a freezing temperature of an electrolyte of the lithium ion battery; calculating a measurement value of a capacity of the lithium ion battery; and calculating at least one of a material deterioration ratio representing a ratio of an amount of lowering in capacity due to deterioration of a material to a whole amount of lowering in capacity of the lithium ion battery and a precipitation deterioration ratio representing a ratio of an amount of lowering in capacity due to precipitation of lithium to the whole amount of lowering in capacity, by using the measurement value of the freezing temperature and the measurement value of the capacity.

Assignees

• Toyota Motor Co Ltd

Inventors

• Kanada Ryo
• Umemura Koji
• Nakatake Akemi

Classifications

• H02J7/825

  Detection of fully charged condition · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M2220/20

  Batteries in motive systems, e.g. vehicle, ship, plane · CPC title

• H02J7/14

  for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle · CPC title

• H01M10/052

  Li-accumulators · CPC title