Search

JP-2026075207-A - Battery management device and battery management method

JP2026075207AJP 2026075207 AJP2026075207 AJP 2026075207AJP-2026075207-A

Abstract

[Problem] To provide a battery management device that can non-destructively detect cell swelling in lithium-ion secondary batteries and suppress cell swelling. [Solution] The battery management device according to this disclosure comprises: an AC signal supply unit that supplies an AC signal to a lithium-ion secondary battery; an impedance detection unit that detects the real value of the AC impedance from the lithium-ion secondary battery to which the AC signal has been supplied; an expansion amount calculation unit that calculates the amount of cell expansion in the lithium-ion 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 lowers the upper limit of the charge rate of the lithium-ion secondary battery as the calculated expansion amount increases. [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 (4)

  1. An AC signal supply unit that supplies AC signals 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 AC signal is supplied, A swelling amount calculation unit calculates the amount of cell swelling 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 lowers the upper limit of the charge level of the lithium-ion secondary battery as the calculated amount of expansion increases. Battery management device.
  2. The AC signal supply unit supplies a first AC signal with a frequency of 500 to 1500 Hz and a second AC signal with a frequency of 0.1 MHz or higher to the lithium-ion secondary battery. The expansion amount calculation unit calculates the expansion amount based on a first change amount, which is the difference between the current value and the initial value of the real part of the AC impedance detected by the first AC signal. The system further includes a Li deposition amount calculation unit that calculates the amount of Li deposited in the lithium-ion secondary battery based on a second change amount, which is the difference between the current value and the initial value of the real part of the AC impedance detected by the second AC signal. The control unit reduces the allowable charging power for the lithium-ion secondary battery as the calculated amount of Li deposition increases. The battery management device according to claim 1.
  3. The Li deposition amount calculation unit corrects the second change amount using the first change amount and calculates the Li deposition amount. The battery management device according to claim 2.
  4. The process of supplying an AC signal 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 AC signal is supplied, A step of calculating the amount of cell expansion 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 process includes a step of lowering the upper limit of the charge rate of the lithium-ion secondary battery as the calculated amount of cell expansion increases. Battery management method.

Description

This disclosure relates to a battery management device and a battery management method. 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 for 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 is a flowchart of the battery management method according to the first embodiment.This graph shows the control pattern of the upper limit of the SOC (State of Cost) relative to the amount of expansion, as controlled by the control unit 14.This is a block diagram showing an example configuration of a battery management system according to the second 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 second AC signal of 1 MHz 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. 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 dissolving a supporting salt. Lithium salts such as LiPF6 and LiBF4 are used as supporting salts. The solvent for the electrolyte is one or a mixture of several of the following: carbonates, esters, ethers