Battery management device and battery management system

Abstract

To provide a battery management device and battery management system that can achieve efficient charging of lithium-ion secondary batteries. [Solution] The battery management device according to the present disclosure comprises: an estimation unit that estimates the negative electrode potential of each of a plurality of stacked battery cells constituting a lithium-ion secondary battery; a control unit that controls the allowable charging power for the lithium-ion secondary battery so that the negative electrode potential of each of the estimated plurality of battery cells shows a value greater than a threshold potential; a high-frequency signal supply unit that supplies a high-frequency signal of 0.1 MHz or higher to the 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 has been supplied; a calculation unit that calculates the amount of Li deposited in the lithium-ion secondary battery from the detected real part value of the AC impedance; and an adjustment unit that adjusts the estimated value of the negative electrode potential by the estimation unit based on the calculated amount of Li deposited.

Description

Technical Field

[0001] The present disclosure relates to a battery management device and a battery management system.

Background Art

[0002] In order to prevent deterioration of the performance of lithium-ion secondary batteries, it is required to suppress the precipitation of metallic Li (lithium) in lithium-ion secondary batteries (hereinafter referred to as Li precipitation). However, a method for non-destructively detecting Li precipitation in lithium-ion secondary batteries has not been known.

[0003] On the other hand, 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 precipitation 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.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, since Li precipitation progresses as the charging power increases, the allowable charging power is set for each type of lithium-ion secondary battery from the viewpoint of suppressing Li precipitation. Here, the progress rate of Li precipitation in lithium-ion secondary batteries has variations (for example, standard deviation σ) for each individual product even within the same type. In conventional lithium-ion secondary batteries, for example, the allowable charging power for each type has been set (fixed) too low so that Li precipitation does not progress in products included in the range of ±6σ, resulting in a problem that the charging time becomes long.

[0006] This disclosure is made in view of the above background and aims to provide a battery management device and battery management system that can achieve efficient charging of lithium-ion secondary batteries. [Means for solving the problem]

[0007] The battery management device according to this disclosure comprises: an estimation unit that estimates the negative electrode potential of each of a plurality of stacked battery cells constituting a lithium-ion secondary battery; a control unit that controls the allowable charging power to the lithium-ion secondary battery such that the estimated negative electrode potential of each of the plurality of battery cells is greater than a threshold potential set as the upper limit potential at which Li deposition begins; and further comprises: a high-frequency signal supply unit that supplies a high-frequency signal of 0.1 MHz or higher to the 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 from the detected real part value of the AC impedance; and an adjustment unit that adjusts the estimated value of the negative electrode potential by the estimation unit based on the calculated amount of Li deposited in the lithium-ion secondary battery. Thus, the battery management device according to this disclosure is a device that feedback-controls the allowable charging power for a lithium-ion secondary battery based on estimated values ​​of the negative electrode potential of each of the stacked battery cells constituting the lithium-ion secondary battery. The device calculates the amount of Li deposited in the lithium-ion secondary battery from the real part value of the AC impedance detected from the lithium-ion secondary battery to which a high-frequency signal is supplied, and adjusts the estimated value of the negative electrode potential based on the calculated result. As a result, the battery management device according to this disclosure can set the allowable charging power for the lithium-ion secondary battery to an appropriate value according to the amount of Li deposited, without setting it excessively low, thereby enabling efficient charging of the lithium-ion secondary battery. [Effects of the Invention]

[0008] This disclosure provides a battery management device and a battery management system that can achieve efficient charging of lithium-ion secondary batteries. [Brief explanation of the drawing]

[0009] [Figure 1] This is a block diagram showing an example configuration of a battery management system according to Embodiment 1. [Figure 2] This figure shows the relationship between the State of Health (SOH) of a secondary battery and the change in the real part Z of the AC impedance when a 1 MHz high-frequency signal is supplied to the secondary battery. [Figure 3] This diagram 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. [Figure 4] This diagram 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. [Figure 5] This diagram illustrates the negative electrode potential of each battery cell. [Figure 6] This is a flowchart showing the operation of the battery management device according to Embodiment 1. [Figure 7] This is a block diagram showing an example configuration of a battery management system according to Embodiment 2. [Modes for carrying out the invention]

[0010] The following describes specific embodiments to which the present invention is applied, with reference to the drawings. However, the present invention is not limited to the following embodiments. Also, for clarity of explanation, the following description and drawings have been simplified as appropriate.

[0011] <Embodiment 1> Figure 1 is a block diagram showing an example configuration of a battery management system according to Embodiment 1. As shown in Figure 1, the battery management system 1 comprises a battery management device 10 and a secondary battery 20 managed by the battery management device 10.

[0012] The secondary battery 20 is a lithium-ion secondary battery and is composed of a cell stack consisting of multiple stacked battery cells and a case that houses the cell stack.

[0013] Each battery cell comprises 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.

[0014] For example, positive electrode active materials include sulfides containing transition metal elements and oxides containing lithium and transition metal elements. Specifically, positive electrode active materials have the basic composition formula Li (1-x) MnO2 (but 0 <x<1)やLi (1-x) Lithium manganese composite oxides such as Mn2O4, with the basic composition formula being Li (1-x) Lithium cobalt composite oxides such as CoO2, with the basic composition formula being Li (1-x) Lithium nickel composite oxides such as NiO2, or the basic composition formula Li (1-x) Ni a Co b Mn c Lithium nickel cobalt manganese composite oxides such as O2 (where a+b+c=1) are used. Note that the positive electrode active material may include other elements in addition to the basic composition formula described above. For the positive electrode current collector, for example, aluminum (Al) is used.

[0015] As the negative electrode active material, for example, a composite oxide containing lithium, a carbon material, etc. are used. Specifically, as the negative electrode active material, inorganic compounds such as lithium, lithium alloys, tin compounds, carbon materials capable of occluding and releasing lithium ions, composite oxides containing a plurality of elements, or conductive polymers, etc. are used. Examples of the carbon material used for the negative electrode active material include cokes, vitreous carbons, graphites, non-graphitizable carbons, pyrolytic carbons, or carbon fibers, etc., and graphites such as artificial graphite and natural graphite are preferable. Also, examples of the composite oxide used for the negative electrode active material include lithium titanium composite oxides, lithium vanadium composite oxides, etc. For the current collector of the negative electrode, for example, Cu (copper) etc. is used.

[0016] The ion conduction medium is used as an electrolytic solution, for example, by dissolving a supporting salt. As the supporting salt, for example, lithium salts such as LiPF6 and LiBF4 are used. As the solvent of the electrolytic solution, for example, any of carbonates, esters, ethers, nitriles, furans, sulfolanes, and dioxolanes, or a mixture of some of them, is used. Examples of the carbonates include cyclic carbonates such as ethylene carbonate, propylene carbonate, vinylene carbonate, butylene carbonate, chloroethylene carbonate, and chain carbonates such as dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl-n-butyl carbonate, methyl-t-butyl carbonate, di-i-propyl carbonate, t-butyl-i-propyl carbonate, etc. Alternatively, as the ion conduction medium, a solid ion conductive polymer, an inorganic solid electrolyte, a mixed material of an organic polymer electrolyte and an inorganic solid electrolyte, or an inorganic solid powder bound by an organic binder, etc. may be used.

[0017] The battery management device 10 performs charging management of the secondary battery 20 to be managed. For example, the battery management device 10 estimates the negative electrode potential of each of the plurality of battery cells constituting the secondary battery 20, and feedback-controls the allowable charging power (the upper limit value of the charging power) Pa for the secondary battery 20 so that the estimated negative electrode potential of each battery cell maintains a value higher than the threshold potential Vth which is the Li precipitation start potential. Further, the battery management device 10 nondestructively detects the amount of Li precipitation in the secondary battery 20, and adjusts the estimated value of the negative electrode potential of each battery cell based on the detected amount of Li precipitation.

[0018] Specifically, the battery management device 10 includes a high-frequency signal supply unit 11, an impedance detection unit 12, a calculation unit 13, a control unit 14, a storage unit 15, an estimation unit 16, and an adjustment unit 17.

[0019] The high-frequency signal supply unit 11 supplies a high-frequency signal to the secondary battery 20. The impedance detection unit 12 detects the value of the real part Z of the AC impedance from the secondary battery 20 to which the high-frequency signal is supplied.

[0020] Incidentally, in the secondary battery 20, by repeating charging, metallic Li is precipitated on the electrode surface of each battery cell. The Li precipitation progresses as the charging power is increased to increase the charging speed, and deteriorates the State Of Health (SOH) of the secondary battery 20. The SOH of the secondary battery 20 is the ratio of the current capacity when the initial capacity of the secondary battery 20 is set to 100%. Therefore, it is desirable to set the allowable charging power Pa as high as possible so that the secondary battery 20 can be efficiently charged in as short a charging time as possible while suppressing Li precipitation.

[0021] Here, if an AC signal (high-frequency signal) with a frequency too high for the diffusion, reaction, and movement of lithium ions in each cell of the secondary battery 20 is supplied to the secondary battery 20, the current of the high-frequency signal flows along the edges of the conductors of each cell due to the skin effect. In other words, the current of the high-frequency signal flows along the electrode surface of each cell where Li is easily deposited due to the skin effect. Furthermore, even when the Li metal is electrically disconnected from the negative electrode and becomes a floating state after Li deposition, current flows on the Li metal due to inductive coupling and electric field coupling. Therefore, for example, the less Li is deposited, the lower the electrical conductivity of the electrode surface of each cell, and the larger the real part Z of the AC impedance. Conversely, the more Li is deposited, the higher the electrical conductivity of the electrode surface of each cell, and the smaller the real part Z of the AC impedance. Here, since a lot of current concentrates in the highly conductive Li metal, the magnetic field changes around the Li deposition region, and eddy currents are generated as a result. These eddy currents cause losses in the conductive parts of the current collector foil and electrodes, but reduce the overall loss of the battery. Therefore, as the amount of Li deposited increases, the change in the magnetic field becomes larger, and consequently the eddy currents increase, so the value of the real part Z decreases. For this reason, the amount of Li deposited in the secondary battery 20 can be calculated from the value of the real part Z of the AC impedance detected from the secondary battery 20 to which a high-frequency signal is supplied. If the amount of Li deposited is known, it is also possible to estimate the SOH of the secondary battery 20.

[0022] Figure 2 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. As indicated by the triangles in Figure 2, in the case of normal charging with low charging power, even if charging is repeated, the amount of Li deposition is small, so even if the deterioration of SOH progresses due to other factors, the change in the real part Z of the AC impedance remains small (i.e., the detected value of the real part Z of the AC impedance is maintained at a high value). In contrast, as indicated by the circles in Figure 2, in the case of rapid charging with high charging power, the amount of Li deposition increases with repeated charging, and consequently, the deterioration of SOH progresses, and the change in the real part Z of the AC impedance becomes large (i.e., the detected value of the real part Z of the AC impedance becomes low). Note that if battery degradation due to Li deposition is the dominant factor among the factors of battery degradation, the amount of Li deposition can be derived from SOH. Alternatively, SOH can be derived from the amount of Li deposition.

[0023] Figures 3 and 4 show the relationship between the frequency of the AC signal supplied to the secondary battery 20 and the real part of the AC impedance detected from the secondary battery 20. Figure 3 shows the value of the real part Z of the AC impedance when an AC signal from 1 kHz to 100 kHz is supplied to the secondary battery 20. Figure 4 shows the value of the real part Z of the AC impedance when an AC signal from 100 kHz to 100 MHz is supplied to the secondary battery 20.

[0024] As shown in Figure 3, when an AC signal near 1 kHz is supplied to the secondary battery 20, the real part Z of the AC impedance is at its minimum value. The impedance component at this time represents the ohmic resistance component. Furthermore, as shown in Figures 3 and 4, as the frequency of the AC signal supplied to the secondary battery 20 increases, the real part Z of the AC impedance increases because the current flow concentrates on the electrode surface of each cell due to the skin effect.

[0025] Therefore, the high-frequency signal supply unit 11 supplies a high-frequency AC signal (i.e., a high-frequency signal) to the secondary battery 20 such that a sufficiently high real part Z value of the AC impedance is detected compared to the ohmic resistance component. For example, the high-frequency signal supply unit 11 supplies a high-frequency signal of 0.1 MHz or higher to the secondary battery 20. Alternatively, the high-frequency signal supply unit 11 supplies a high-frequency signal to the secondary battery 20 such that, compared to the real part Z value of the AC impedance detected when a 1 kHz AC signal is supplied to the secondary battery 20, a real part value of the AC impedance is detected by the skin effect at least 10 times higher. In the examples of Figures 3 and 4, the high-frequency signal supply unit 11 supplies a high-frequency signal of 0.5 MHz or higher to the secondary battery 20. As a result, the current of the high-frequency signal flows through the electrode surface (Li deposition region) of each battery cell of the secondary battery 20 due to the skin effect. As a result, the impedance detection unit 12 can detect the real part Z of the AC impedance according to the amount of Li deposition.

[0026] The calculation unit 13 calculates the amount of Li deposited in the secondary battery 20 from the value of the real part Z of the AC impedance detected by the impedance detection unit 12. More specifically, the calculation unit 13 calculates the amount of Li deposited in the secondary battery 20 based on the difference between the current value of the real part Z of the AC impedance detected by the impedance detection unit 12 and the initial value of the real part Z of the AC impedance of the secondary battery 20. Information on the initial value of the real part Z of the AC impedance of the secondary battery 20 being managed is stored, for example, in the storage unit 15.

[0027] For example, the calculation unit 13 calculates a smaller Li deposition amount the larger the real part Z value of the detected AC impedance is, and calculates a larger Li deposition amount the smaller the real part Z value of the detected AC impedance is.

[0028] The memory unit 15 may also store information on the initial value of the real part Z of the AC impedance for each type of secondary battery. Furthermore, the memory unit 15 may store map information representing the relationship between the current value (detected value) and the difference (change amount) between the initial value and the amount of Li deposition of the real part Z of the AC impedance for each type of secondary battery. This map information is, for example, information obtained in advance through experiments, but may be updated as appropriate based on information detected from the secondary battery 20 under management. In this case, the calculation unit 13 extracts the amount of Li deposition corresponding to the value of the real part Z of the AC impedance detected by the impedance detection unit 12 from the map information stored in the memory unit 15.

[0029] The estimation unit 16 estimates the negative electrode potential of each of the multiple battery cells that make up the secondary battery 20. The estimation unit 16 may estimate the negative electrode potential of one or more of the multiple battery cells that make up the secondary battery 20, and then estimate the negative electrode potential of all of the multiple battery cells that make up the secondary battery 20 from the estimation result.

[0030] Figure 5 is a diagram illustrating the negative electrode potential. As shown in Figure 5, the negative electrode potential of each battery cell in the secondary battery 20 during charging is represented by the "positive electrode potential" minus the "measured cell voltage" of that battery cell. The positive electrode potential of a battery cell is estimated from the positive electrode Open Circuit Potential (OCP), the potential rise in the positive electrode resistance, and the potential rise in the positive electrode polarization. The positive electrode OCP of a battery cell is extracted as a value corresponding to the State of Charge (SOC) of that battery cell from map information showing the relationship between the State of Charge (SOC) and the positive electrode OCP of that battery cell.

[0031] The control unit 14 feedback-controls the allowable charging power Pa for the secondary battery 20 so that the negative electrode potential of each battery cell, estimated by the estimation unit 16, remains greater than the threshold potential Vth, which is set as the upper limit potential at which Li deposition begins. The threshold potential Vth is, for example, 0V. When the negative electrode potential of each battery cell falls below the threshold potential Vth, the likelihood of Li deposition progressing in each battery cell increases.

[0032] The adjustment unit 17 adjusts the estimated negative electrode potential of each battery cell calculated by the estimation unit 16 based on the amount of Li deposited calculated by the calculation unit 13.

[0033] Here, even though the control unit 14 controls the allowable charging power Pa for the secondary battery 20 so that the negative electrode potential of each battery cell remains greater than the threshold potential Vth, if Li deposition is progressing in each battery cell, the estimated value of the negative electrode potential of each battery cell by the estimation unit 16 may be higher than the actual value. In this case, even if the estimated value of the negative electrode potential of each battery cell shows a value higher than the threshold potential Vth, the actual value of the negative electrode potential of each battery cell may be less than or equal to the threshold potential Vth. When the negative electrode potential of each battery cell falls below the threshold potential Vth, the likelihood of Li deposition progressing in each battery cell increases. This error in the estimate is mainly due to estimation errors of the positive electrode potential caused by the positive electrode OCP, the potential rise in the positive electrode resistance, and the potential rise in the positive electrode polarization.

[0034] Therefore, the adjustment unit 17 adjusts the system so that the estimated value of the negative electrode potential of each battery cell calculated by the estimation unit 16 decreases as the amount of Li deposition calculated by the calculation unit 13 increases (in other words, as the degree of Li deposition progresses). The adjustment unit 17 may also gradually decrease the estimated value of the negative electrode potential from the initial value to 95% of the initial value, 90% of the initial value, etc., as the calculated amount of Li deposition increases.

[0035] For example, the adjustment unit 17 may learn improvements to the parameters and map information used to estimate the negative electrode potential of each battery cell, taking into account the amount of Li deposition calculated by the calculation unit 13, and update the parameters and map information used to estimate the negative electrode potential of each battery cell using the learned model. These improvements may also be applied to the next generation of parameters and map information used to estimate the negative electrode potential of the battery cells.

[0036] Alternatively, the adjustment unit 17 may gradually decrease the estimated values ​​of the potential rise in the positive electrode resistance and the potential rise in the positive electrode polarization, which are highly SOC-dependent, as the amount of Li deposition calculated by the calculation unit 13 increases. Note that if the secondary battery 20 is an LFP (lithium iron phosphate battery), the SOC dependence of the positive electrode potential is low, so adjusting the cell upper limit voltage (voltage threshold to protect the cell upper limit voltage) of each battery cell can be used to obtain an effect that is substantially the same as adjusting the estimated value of the negative electrode potential of each battery cell.

[0037] As a result, the battery management device 10 according to this disclosure can set the highest possible allowable charging power Pa for the secondary battery 20, enabling efficient charging in the shortest possible charging time while suppressing Li deposition. In other words, the battery management device 10 according to this disclosure can set the allowable charging power Pa for the secondary battery 20 to an appropriate value according to the amount of Li deposition, without setting it excessively low, thereby enabling efficient charging of the secondary battery 20.

[0038] (Operation of battery management device 10) Next, we will explain the operation of the battery management device 10 using Figure 6. Figure 6 is a flowchart showing the operation of the battery management device 10.

[0039] First, the battery management device 10 estimates the negative electrode potential of each of the multiple battery cells that make up the secondary battery 20 (step S101). Then, the battery management device 10 controls the allowable charging power Pa for the secondary battery 20 so that the estimated negative electrode potential of each battery cell remains greater than the threshold potential Vth set as the Li deposition start potential (step S102).

[0040] Furthermore, the battery management device 10 supplies the secondary battery 20 with an AC signal (high-frequency signal) of such a high frequency that the diffusion, reaction, and movement of lithium ions in each battery cell cannot keep up (step S103). For example, the battery management device 10 supplies the secondary battery 20 with a high-frequency signal of 0.1 MHz or higher. The battery management device 10 then detects the value of the real part Z of the AC impedance from the secondary battery 20 to which the high-frequency signal has been supplied (step S104).

[0041] Subsequently, the battery management device 10 calculates the amount of Li deposited in the secondary battery 20 from the detected real part Z value of the AC impedance (step S105). For example, the battery management device 10 extracts the amount of Li deposited corresponding to the detected real part Z value of the AC impedance from the map information stored in the storage unit 15. Basically, the larger the detected real part Z value of the AC impedance, the smaller the Li deposited amount calculated by the battery management device 10, and the smaller the detected real part Z value of the AC impedance, the larger the Li deposited amount calculated.

[0042] Subsequently, the battery management device 10 adjusts the estimated negative electrode potential of each battery cell based on the calculated amount of Li deposition (step S106). For example, if the calculated amount of Li deposition is small, the estimated negative electrode potential of each battery cell is close to the actual value, and the progress of Li deposition is suppressed, so the battery management device 10 does not adjust the negative electrode potential of each battery cell. On the other hand, if the calculated amount of Li deposition is large, the estimated negative electrode potential of each battery cell is higher than the actual value, and there is a high possibility that Li deposition is progressing, so the battery management device 10 adjusts the estimated negative electrode potential of each battery cell to be lower. This suppresses the progress of Li deposition.

[0043] Thus, the battery management device 10 according to this disclosure can set the allowable charging power Pa of the secondary battery 20 to the highest possible value, which allows for efficient charging in the shortest possible charging time while suppressing Li deposition. In other words, the battery management device 10 according to this disclosure can set the allowable charging power Pa of the secondary battery 20 to an appropriate value according to the amount of Li deposition, without setting it excessively low, thereby enabling efficient charging of the secondary battery 20.

[0044] <Embodiment 2> Figure 7 is a block diagram showing an example configuration of the battery management system 100 according to Embodiment 2. The battery management system 100 comprises n battery management devices 10, each corresponding to n (where n is an integer of 2 or more) secondary batteries 20, a control device 40, and a network 50. The n battery management devices 10 and the control device 40 are configured to communicate with each other via the network 50. Hereinafter, the n secondary batteries 20 will also be referred to as secondary batteries 20_1 to 20_n, and the n battery management devices 10 will also be referred to as battery management devices 10_1 to 10_n.

[0045] The secondary batteries 20_1 to 20_n are installed in vehicles 30_1 to 30_n, respectively. The battery management devices 10_1 to 10_n are also installed in vehicles 30_1 to 30_n together with the secondary batteries 20_1 to 20_n. All of the vehicles 30_1 to 30_n are electric vehicles or hybrid vehicles powered by secondary batteries.

[0046] The control device 40 controls the adjustment of the estimated negative electrode potential in each of the secondary batteries 20_1 to 20_n, according to the adjustment status of the estimated negative electrode potential in one or more secondary batteries 20_1 to 20_n, which are managed by the battery management devices 10_1 to 10_n.

[0047] For example, if the estimated negative electrode potential of a predetermined number of secondary batteries 20 managed by a predetermined number of battery management devices 10_1 to 10_n is adjusted to a value lower than the initial value, the initial estimated negative electrode potential may be too high. In such a case, the control device 40 adjusts the estimated negative electrode potential to a lower value for all secondary batteries 20_1 to 20_n managed by the battery management devices 10_1 to 10_n. This suppresses the progression of Li deposition in each secondary battery 20_1 to 20_n. The control device 40 may also set the initial estimated negative electrode potential for newly shipped secondary batteries 20 to a low value, similar to the case of secondary batteries 20_1 to 20_n.

[0048] This disclosure can be realized by having a Central Processing Unit (CPU) execute a computer program to perform some or all of the processing of the battery management device 10.

[0049] The program described above includes, when loaded into a computer, a set of instructions (or software code) for causing the computer to perform one or more of the functions described in the embodiments. The program may be stored in a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited to, include Random-Access Memory (RAM), Read-Only Memory (ROM), flash memory, Solid-State Drive (SSD), or other memory technologies, CD-ROM, Digital Versatile Disc (DVD), Blu-ray® disc, or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited to, include temporary computer-readable medium or a communication medium that includes electrically, optically, acoustically, or otherwise propagating signals.

[0050] Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications to the structure and details of the present disclosure can be made as understandable to those skilled in the art within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate. [Explanation of symbols]

[0051] 1. Battery Management System 10 Battery management device 10_1~10_n Battery management device 11. High-frequency signal supply unit 12 Impedance detection unit 13 Calculation Section 14 Control Unit 15 Storage section 16 Estimation part 17 Adjustment part 20 Secondary battery 20_1~20_n Secondary battery 30_1~30_n Vehicles 40 Control device 50 Networks 100 Battery Management System

Claims

1. An estimation unit that estimates the negative electrode potential of each of the multiple stacked battery cells that make up a lithium-ion secondary battery, A control unit controls the allowable charging power for the lithium-ion secondary battery such that the estimated negative electrode potential of each of the plurality of battery cells is greater than the threshold potential set as the upper limit potential at which Li deposition begins. A battery management device equipped with, A high-frequency signal supply unit that supplies a high-frequency signal of 0.1 MHz or higher to the 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 from the real value of the detected AC impedance, An adjustment unit adjusts the estimated value of the negative electrode potential by the estimation unit based on the calculated amount of Li deposited in the lithium-ion secondary battery, A battery management device further equipped with [features].

2. The high-frequency signal supply unit supplies the lithium-ion secondary battery with a high-frequency signal of such a frequency that, compared to the real part value of the AC impedance detected when a 1 kHz AC signal is supplied to the lithium-ion secondary battery, the real part value of the AC impedance is detected to be 10 times or more due to the skin effect. The battery management device according to claim 1.

3. The adjustment unit adjusts the estimated value of the negative electrode potential by the estimation unit so that the higher the calculated amount of Li deposited in the lithium-ion secondary battery, the lower the estimated value of the negative electrode potential. The battery management device according to claim 1.

4. The estimation unit estimates the negative electrode potential of each of the plurality of battery cells based on the result of estimating the negative electrode potential of one or more of the plurality of battery cells. The battery management device according to claim 1.

5. A plurality of battery management devices according to claim 1 for managing a plurality of lithium-ion secondary batteries installed in each of a plurality of vehicles, A control device that controls the adjustment content of the estimated negative electrode potential in each of the plurality of lithium-ion secondary batteries according to the adjustment status of the estimated negative electrode potential in one or more of the plurality of lithium-ion secondary batteries, A battery management system equipped with this feature.

Images