JP-2026075208-A - Battery management device and battery management method

JP2026075208AJP 2026075208 AJP2026075208 AJP 2026075208AJP-2026075208-A

Abstract

[Problem] To provide a battery management device that can appropriately set the allowable charging power at the start of use of a refurbished lithium-ion secondary battery, even when the lithium-ion secondary battery is a refurbished product and the initial value of the actual part of the AC impedance is unknown. [Solution] A battery management device comprising: a high-frequency signal supply unit that supplies a high-frequency signal of 0.1 MHz or higher to a lithium-ion secondary battery; an impedance detection unit that detects the real value of the AC impedance from the secondary battery to which the high-frequency signal has been supplied; a calculation unit that calculates the amount of Li deposited in the secondary battery based on the difference between the current value and the initial value of the detected real value of the AC impedance; and a control unit that reduces the allowable charging power for the secondary battery as the calculated amount of Li deposited increases. If the secondary battery is a reused product and the initial value of the secondary battery is unknown, a predetermined value based on the average value of initial values for secondary batteries of the same type as the secondary battery is set as the initial value of the secondary battery. [Selection Diagram] Figure 1

Inventors

西勇二
菊池義晃
真野亮
田代広規
石川敬祐

Assignees

トヨタ自動車株式会社
株式会社豊田中央研究所

Dates

Publication Date: 20260508
Application Date: 20241022

Claims (5)

A high-frequency signal supply unit that supplies high-frequency signals of 0.1 MHz or higher to a lithium-ion secondary battery, An impedance detection unit that detects the real part value of the AC impedance from the lithium-ion secondary battery to which the high-frequency signal is supplied, A calculation unit that calculates the amount of Li deposited in the lithium-ion secondary battery based on the difference between the current value and the initial value of the detected AC impedance real part, The system includes a control unit that reduces the allowable charging power for the lithium-ion secondary battery as the calculated amount of Li deposition increases, If the lithium-ion secondary battery is a reused product and the initial value of the lithium-ion secondary battery is unknown, A predetermined value based on the average value of the initial values for the same type of lithium-ion secondary battery is set as the initial value for the lithium-ion secondary battery. Battery management device.
The frequency of the aforementioned high-frequency signal is 0.5 MHz or higher. The battery management device according to claim 1.
The control unit outputs an alarm prohibiting the use of the lithium-ion secondary battery when the calculated amount of Li deposition reaches a predetermined reference value. The battery management device according to claim 1 or 2.
The control unit increases the amount of decrease in the allowable charging power in response to an increase in the amount of Li deposition as the amount of Li deposition approaches the predetermined reference value, so that the calculated amount of Li deposition does not reach a predetermined reference value. The battery management device according to claim 1 or 2.
A process of supplying a high-frequency signal of 0.1 MHz or higher to a lithium-ion secondary battery, A step of detecting the real part value of the AC impedance from the lithium-ion secondary battery to which the high-frequency signal is supplied, A step of calculating the amount of Li deposited in the lithium-ion secondary battery based on the difference between the current value and the initial value of the detected real part of the AC impedance, The process includes reducing the allowable charging power for the lithium-ion secondary battery as the calculated amount of Li deposited increases, In the process of calculating the amount of Li precipitated, If the lithium-ion secondary battery to be managed is a reused product and the initial value of the lithium-ion secondary battery is unknown, A predetermined value based on the average value of the initial values for the same type of lithium-ion secondary battery is set as the initial value for the lithium-ion secondary battery. Battery management method.

Description

This disclosure relates to a battery management device and a battery management method. To prevent performance degradation in lithium-ion secondary batteries, it is necessary to suppress the deposition of metallic lithium (Li) (hereinafter referred to as Li deposition) in lithium-ion secondary batteries. However, no non-destructive method for detecting Li deposition in lithium-ion secondary batteries was known. In response to this, as disclosed in Patent Document 1, the inventors have developed a method for detecting the real part of the AC impedance of a lithium-ion secondary battery using a high-frequency signal, and calculating the amount of Li deposited in the lithium-ion secondary battery based on the difference between the current value and the initial value of the real part of the AC impedance. Japanese Patent Publication No. 2022-108602 This is a block diagram showing an example configuration of a battery management system according to the first embodiment.This graph shows the relationship between the State of Health (SOH) of the secondary battery 20 and the change in the real part Z of the AC impedance (the difference between the detected value and the initial value) when a 1 MHz high-frequency signal is supplied to the secondary battery 20.This graph shows the relationship between the frequency of the AC signal supplied to the secondary battery and the real part of the AC impedance detected from the secondary battery.This graph shows the relationship between the frequency of the AC signal supplied to the secondary battery and the real part of the AC impedance detected from the secondary battery.This is a flowchart of the battery management method according to the first embodiment.This graph shows the control pattern of the allowable charging power Pa in relation to the amount of Li deposition by the control unit 14. The following describes specific embodiments of the present invention in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. Furthermore, for clarity, the following description and drawings have been simplified as appropriate. (First embodiment) Figure 1 is a block diagram showing an example configuration of a battery management system according to the first embodiment. As shown in Figure 1, the battery management system comprises a battery management device 10 and a secondary battery 20 managed by the battery management device 10. <Configuration of the secondary battery 20> First, let's explain the secondary battery 20, which is the subject of management. The secondary battery 20 is a lithium-ion secondary battery and is composed of a cell stack consisting of a plurality of stacked battery cells and a case that houses the cell stack. Each battery cell includes a positive electrode, a negative electrode, and an ion transport medium provided between the positive and negative electrodes for conducting carrier ions. A separator may be further provided between the positive and negative electrodes. The separator is made of a resin such as polyethylene or polypropylene. For example, the positive electrode active material may be a sulfide containing a transition metal element or an oxide containing lithium and a transition metal element. Specifically, the positive electrode active material may be a lithium manganese composite oxide with a basic composition formula such as Li (1-x) MnO₂ (where 0 < x < 1) or Li (1-x) Mn₂O₄ , a lithium cobalt composite oxide with a basic composition formula such as Li (1-x) CoO₂ , a lithium nickel composite oxide with a basic composition formula such as Li (1-x) NiO₂ , or a lithium nickel cobalt manganese composite oxide with a basic composition formula such as Li (1-x) Ni aCo bMn cO₂ (where a + b + c = 1). In addition, the positive electrode active material may be a substance that includes other elements in the basic composition formulas mentioned above. For the current collector of the positive electrode, for example, Al (aluminum) may be used. The negative electrode active material can be, for example, a lithium-containing composite oxide or a carbon material. Specifically, the negative electrode active material can be an inorganic compound such as lithium, lithium alloys, or tin compounds; a carbon material capable of intercalating and deintercalating lithium ions; a composite oxide containing multiple elements; or a conductive polymer. Examples of carbon materials used in the negative electrode active material include coke, glassy carbons, graphites, non-graphitizable carbons, pyrolytic carbons, or carbon fibers, but graphites such as artificial graphite or natural graphite are preferred. Examples of composite oxides used in the negative electrode active material include lithium-titanium composite oxide and lithium-vanadium composite oxide. For the current collector of the negative electrode, for example, Cu (copper) is used. The ion-conducting medium is used as an electrolyte, for example, by d