Detection device, management apparatus, and detection method

Abstract

The detection device includes a detector and a controller. The detector has at least one resonator circuit that applies at least one specific frequency vibration to a lithium-ion secondary battery, measures an attenuation characteristic of at least one resonance current, and outputs the attenuation characteristic as a detection signal. The controller detects the presence of lithium deposition and / or an impurity metal inside the lithium-ion secondary battery by using the detection signal of the attenuation characteristic acquired from the detector.

Description

Technical Field

[0001] This manual discloses the testing apparatus, management equipment, and testing methods. Background Technology

[0002] In the prior art, proposed methods for determining the degradation of power storage devices involve, for example, measuring battery impedance at multiple frequencies and detecting corrosion degradation in the current collector of a lead-acid battery based on the real components of the impedance (see, for example, Patent Document 1). Proposed methods for determining the degradation of lithium-ion secondary batteries involve measuring the freezing temperature and volume of the electrolyte solution and using these measurements to determine the percentage of capacity reduction due to lithium deposition (see, for example, Patent Document 2). In such degradation determination methods, the capacity reduction due to material degradation and the capacity reduction due to lithium deposition can be accurately calculated.

[0003] Reference List

[0004] Patent documents

[0005] PTL 1: JP 6436271 B

[0006] PTL 2: JP 2018-200800 A Summary of the Invention

[0007] Technical issues

[0008] However, while Patent Document 1 considers corrosion-related degradation in lead-acid battery current collectors, it does not consider lithium deposition-related degradation in lithium-ion secondary batteries. Patent Document 2 is not a simple technology because it requires measuring the freezing temperature of the electrolyte solution. Therefore, a new technology is needed.

[0009] This disclosure was conceived in view of the above problems, and its main objective is to provide new detection devices, management equipment and detection methods that can detect the state of lithium-ion secondary batteries by using a simpler configuration and easier technology.

[0010] Solution to the problem

[0011] After diligent research to achieve the above objectives, the inventors have discovered that by applying a specific frequency vibration to a lithium-ion secondary battery using a resonator circuit, the real impedance of the battery can be estimated based on the resonant current decay characteristics, and the internal state of the battery, such as the amount of lithium deposition and the formation of the capping layer, can be further estimated based on the battery resistance. The invention disclosed in this specification has been completed.

[0012] Specifically, the detection device disclosed in this specification will detect the state of a lithium-ion secondary battery. The detection device includes a detector and a controller. The detector has at least one resonator circuit that applies at least one specific frequency vibration to the lithium-ion secondary battery, measures the decay characteristics of at least one resonant current, and outputs the decay characteristics as a detection signal. The controller uses the detection signal of the decay characteristics obtained from the detector to detect the presence of lithium deposits and / or impurity metals inside the lithium-ion secondary battery.

[0013] The management device disclosed in this specification manages the lithium-ion secondary battery based on information obtained from the aforementioned detection device. The management device includes a management unit that utilizes the lithium-ion secondary battery using detection results from the controller regarding lithium deposition inside the battery, while limiting its use based on the remaining volume of active lithium.

[0014] The detection method disclosed in this specification is used to detect the state of a lithium-ion secondary battery. The detection method includes: an output step for applying at least one specific frequency vibration to the lithium-ion secondary battery, measuring the attenuation characteristics of at least one resonant current, and outputting the attenuation characteristics as a detection signal; and a detection step for detecting the presence of lithium deposition and / or impurity metals inside the lithium-ion secondary battery by using the detection signal of the attenuation characteristics acquired in the output step.

[0015] Beneficial effects of the present invention

[0016] The detection apparatus, management device, and detection method according to this disclosure allow for the detection of the state of lithium-ion secondary batteries using a simpler configuration and easier techniques. The present invention is considered to exhibit this advantage for the following reasons. For example, by applying vibration at a specific frequency to the lithium-ion secondary battery using a resonator circuit, the battery resistance can be estimated based on the resonant current decay characteristics. Furthermore, for example, the internal state of the battery, such as the amount of lithium deposition and the formation of a capping layer, can be estimated based on the battery resistance. This disclosure utilizes a detector with a simple resonator circuit capable of detecting the state of individual cells in an on-board manner when using lithium-ion secondary batteries. Therefore, in this disclosure, the state of lithium-ion secondary batteries can be detected using a simpler configuration and easier techniques. Attached Figure Description

[0017] Figure 1 An example of the battery management system 10 is shown.

[0018] Figure 2 An example of the detection device 32 is shown.

[0019] Figure 3 An example of detector 300 and controller 310 is shown.

[0020] Figure 4 An example of another detector 300A and another controller 310A is shown.

[0021] Figure 5 An example of detector 300 is shown.

[0022] Figure 6 An example of another detector, the 300B, is shown.

[0023] Figure 7 An example of detector 300B is shown.

[0024] Figure 8 An example of controller 310 is shown.

[0025] Figure 9 Another example of a circuit configuration is shown.

[0026] Figure 10 Examples of inductors L1 and L2 are shown.

[0027] Figure 11 An example of an equivalent circuit model is shown.

[0028] Figure 12 This shows the relationship between frequency and the real part of impedance under degraded conditions.

[0029] Figure 13 An example is shown showing the resonant current decay characteristics.

[0030] Figure 14 This is a flowchart illustrating a general overview of the computational processes used to detect the state of a single entity.

[0031] Figure 15 This is a flowchart illustrating an example of a detection processing routine.

[0032] Figure 16 Various modes of the detection device 32 are shown.

[0033] Figure 17 An example of a detection device 32F with a series-connected unit 301 is shown.

[0034] Figure 18 An example of a detection device 32G with parallel connected units 301 is shown.

[0035] Figure 19 An example of a detection device 32H connected to multiple units 301 is shown.

[0036] Figure 20 An example of a standalone leased data storage system is shown.

[0037] Figure 21 An example of a standalone sales data storage system is shown.

[0038] Figure 22 An example of another detector 300C is illustrated.

[0039] Figure 23 Another example of another detector 300D is illustrated.

[0040] Figure 24 Another example of another detector 300E is illustrated. Detailed Description of Embodiments

[0041] (Battery management system 10)

[0042] Embodiments of the detection device disclosed in the present specification are described below with reference to the accompanying drawings. Figure 1 An example of a battery management system 10 is schematically illustrated. Figure 2 An example of a detection device 32 is illustrated. Figure 3 An example of a detector 300 and a controller 310 is illustrated. Figure 4 An example of another detector 300A and another controller 310A is illustrated. Figure 5 An example of a detector 300 is illustrated. Figure 6 An example of another detector 300B is illustrated. Figure 7 An example of the detector 300B is illustrated. Figure 8 An example of a controller 310 is illustrated. Figure 9 An example of another circuit configuration is illustrated. Figure 10 An example of inductors L1 and L2 is illustrated.

[0043] First, a cell 301 serving as a measurement target will be described. The cell 301 serves as a lithium-ion secondary battery. The cell 301 may, for example, include a positive electrode, a negative electrode, and an ion-conducting medium inserted between the positive electrode and the negative electrode for conducting carrier ions therebetween. For example, the positive electrode may use a sulfide containing a transition metal element or an oxide containing lithium and a transition metal element as a positive electrode active material. Examples of the positive electrode active material used may include Li (1-x) MnO2 (where 0<x<1, the same applies hereinafter) or Li (1-x) Mn2O4 as a lithium manganese composite oxide with a basic constituent molecular formula, Li (1-x) CoO2 as a lithium cobalt composite oxide with a basic constituent molecular formula, Li (1-x) NiO2 as a lithium nickel composite oxide with a basic constituent molecular formula, and Li (1-x) Ni a Co b Mn cO2 (a+b+c=1) is a lithium-nickel-cobalt-manganese composite oxide with the basic molecular formula. The "basic molecular formula" may include other elements. The negative electrode may include a composite oxide containing carbon materials or lithium as the negative electrode active material. Examples of negative electrode active materials include lithium, lithium alloys, inorganic compounds (e.g., tin compounds), carbon materials capable of blocking and releasing lithium ions, composite oxides containing multiple elements, and conductive polymers. Examples of carbon materials include char groups, glassy carbon groups, graphite groups, non-graphitized carbon groups, pyrolytic carbon groups, and carbon fibers. In these examples, graphite groups (e.g., artificial graphite or natural graphite) are preferred. Examples of composite oxides include lithium-titanium composite oxides and lithium-vanadium composite oxides. The ion-conducting medium may be, for example, an electrolyte solution in which a supporting electrolyte is dissolved. The supporting electrolyte may be, for example, a lithium salt (e.g., LiPF6 or LiBF4). Examples of solvents for the electrolyte solution include carbonate groups, ester groups, ether groups, nitrile groups, furan groups, sulfolane groups, and dioxolane groups, which may be used alone or in mixtures. Specifically, the carbonate group can be a cyclic carbonate group, such as ethylene carbonate, propylene carbonate, vinylene carbonate, butylene carbonate, or vinyl chloride carbonate, or a chain carbonate group, such as dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl butyrate carbonate, methyl butyrate carbonate, dipropyl carbonate, or butyl propyl carbonate. The ion-conducting medium used can be a solid ion-conducting polymer, an inorganic solid electrolyte, a mixture of an organic polymer electrolyte and an inorganic solid electrolyte, or an inorganic solid powder bonded together by an organic binder. Monomer 301 can have a separator disposed between the positive and negative electrodes.

[0044] For example, the battery management system 10 is a system for selling and managing the use of each manufactured lithium-ion secondary battery (i.e., cell 301). The battery management system 10 includes a manufacturer server 20, a management server 25, and a battery system 30. The manufacturer server 20 is owned by the manufacturer of the cell 301 and acts as a management device for managing the lithium-ion secondary batteries based on information obtained from the detection device 32. The manufacturer server 20 can cause the management unit 21 to perform quality control by obtaining information from the battery system 300 regarding the presence of impurity metals contained in the cell 301.

[0045] The management server 25 is owned by the administrator of the individual cell 301 during use and acts as a management device for managing the lithium-ion secondary battery based on information obtained from the detection device 32. The management server 25 enables storage units 27 and 28 to store, for example, information related to the state of the individual cell 301 obtained from the battery system 30, and enables the management unit 26 to perform processing for setting details of the recovery, replacement, and maintenance of the individual cell 301 in use. For example, the management server 25 can utilize the lithium-ion secondary battery using the detection results from the detection device 32 regarding lithium deposition inside the lithium-ion secondary battery, while limiting its use based on the remaining volume of active lithium. Furthermore, the management server 25 can use the detection results from the detection device 32 regarding lithium deposition inside the lithium-ion secondary battery to perform processing to quantify the residual value (including remaining usage time) of the lithium-ion secondary battery based on the remaining volume of active lithium. Alternatively, the management server 25 can calculate a distribution value using the detection results from the detection device 32 regarding lithium deposition inside the lithium-ion secondary battery and output the calculated distribution value.

[0046] The battery system 30 is a system that drives a load 31 using individual cells 301. The battery system 30 can be used, for example, as a vehicle drive system or a home energy supply system. The battery system 30 is equipped with a detection device 32 for detecting the state of the individual cells 301. Furthermore, the battery system 30 has sensors necessary for managing and controlling the individual cells 301, such as a temperature sensor 311 for measuring the temperature of the individual cells 301. The state of the individual cells 301 that the detection device 32 can detect includes, for example, lithium deposition and degradation states, such as the formation of a capping layer. In addition, the detection device 32 can detect the state of mixed impurity metals inside the battery.

[0047] like Figure 1 and Figure 2 As shown, the detection device 32 includes a detector 300 and a controller 310. The detector 300 acts as a sensor connected to a single cell 301, which acts as a measurement target in an on-board manner. The detector 300 has at least one resonator circuit 302 that applies at least one specific frequency vibration to the lithium-ion secondary battery, measures the attenuation characteristics of at least one resonant current, and outputs the attenuation characteristics as a detection signal to the controller 310. Figure 2As shown, detector 300 may include at least one resonator circuit 302, a wave sensor 303 that outputs a signal from resonator circuit 302 as a detection signal, and a drive circuit 304 that drives resonator circuit 302. Controller 310 acts as a battery monitoring unit (BMU), receiving detection signals from detector 300 and acquiring and managing information related to the state of individual cells 301. Controller 310 may be connected to multiple detectors 300. Controller 310 can detect at least one of lithium deposition and the presence of impurity metals within any one of the multiple parallel or series-connected cells 301 of a lithium-ion secondary battery. Controller 310 detects the presence of lithium deposition and / or impurity metals within the lithium-ion secondary battery by using a decay characteristic detection signal acquired from detector 300. Figure 2 As shown, the controller 310 may include an isolator 305 that outputs a drive signal to the drive circuit 304 of the detector 300, a logic calculator 306 that calculates the detection signal output from the detector 300, and a main calculator 307 that outputs a drive signal to the isolator 305 and receives the detection signal from the logic calculator 306.

[0048] For example, detector 300 may have Figures 3 to 7 Any of the configurations shown is used as a specific example. Figure 3 As shown, the resonator circuit 302 comprises a closed circuit including an inductor L1 equipped with a pickup coil connected in parallel to the cell 301, a resonant capacitor C1 connected in series to the inductor L1, a resistor R1 connected in parallel to the resonant capacitor C1, and a semiconductor switch S1 connected in series to the inductor L1. The resonator circuit 302 can apply frequency vibrations within a frequency range of less than 5 MHz, which is frequency region A1, to the cell 301. For example, frequency region A1 can be 0.5 MHz or higher, and its range can be between 0.8 MHz and 2 MHz. Within this range, the deposition state of lithium is easily determined. Alternatively, the resonator circuit 302 can apply frequency vibrations within a frequency range of more than 10 MHz, which is frequency region A2, to the cell 301. For example, frequency region A2 can be less than 100 MHz, and its range can be between 20 MHz and 40 MHz. Within this range, the deposition state of the capping layer is easily determined. The wave sensor 303 can rectify the signal output from the resonator circuit 302 and output the signal as a detection signal. For example, as... Figure 3 and Figure 5 As shown, the wave sensor 303 may have a pickup coil L2, a rectifier circuit 308, and a filter 309. The pickup coil L2 is positioned facing the inductor L1 and detects the resonant current flowing through the inductor L1. The rectifier circuit 308 may be constructed from a diode bridge including diodes Dr1 to Dr4 connected to the pickup coil L2. Figure 5 As shown, filter 309 may include capacitor Cf and resistor Rf, which can filter the rectified waveform and output the detection signal to controller 310, which acts as a BMU. Alternatively, as... Figure 4 As shown, as long as the wave sensor 303 can output the signal from the resonator circuit 302 as a detection signal, the rectifier circuit 308 and filter 309 can be omitted from the wave sensor 303. The drive circuit 304 is the circuit that turns on the semiconductor switch S1. For example, as Figure 5 As shown, the drive circuit 304 can drive the semiconductor switch S1 via the drive capacitor Cx1 connected in parallel to the single cell 301 through the diode Dx1 and via the buffer BUF1 which is powered from the drive capacitor Cx1.

[0049] For example, controller 310 may have Figure 3 , Figure 4 and Figure 8 Any of the configurations shown. Controller 310 can detect the presence of lithium deposition and / or impurity metals by estimating the battery resistance Rbat using voltage values ​​Venv1 and Venv2 as resonant current decay characteristics. Figure 3 and Figure 8 As shown, the logic calculator 306 may have one or more sample-and-hold circuits. The isolator 305 may have a series capacitor and may output a drive signal to the drive circuit 304. The isolator 305 may be a simple series capacitor, and the logic calculator 306 may have two to three sample-and-hold circuits. In the detection device 32, the transmitted signal from the controller 310 is isolated by the isolator 305, and the signal from the detector 300 is isolated by the action of the pickup coil. Therefore, the detection device 32 is characterized by its ability to perform measurements on a large-capacity module consisting of multiple series-connected cells 301 that act as measurement targets. When the resonator circuit 302 is subjected to frequency vibrations in the range below 5 MHz, the controller 310 may detect the presence of lithium deposition and / or impurity metals inside the lithium-ion secondary battery based on the decrease in the real part of the impedance. Furthermore, when the resonator circuit 302 is subjected to frequency vibrations in the range above 10 MHz, the controller 310 may detect the coating layer formed on the electrodes of the cell 301 based on the increase in the real part of the impedance.

[0050] like Figure 4 As shown, the detection device 32 can provide a pickup coil for the drive circuit 304, a resonant coil for the isolator 305, and may include a detector 300A and a controller 310 that physically separate the drive circuit 304 from the isolator 305 and physically separate the resonator circuit 302 from the wave sensor 303. Figure 4In this configuration, RFID is used for the input signal, and an RFID-TAG that can operate without power is used on the drive circuit 304 side, thereby enabling sensor operation and signal reception entirely wirelessly. While the coupling coefficient may be an issue when establishing a wireless configuration, it is not a problem because the input signal is a digital signal with values ​​of 1 or 0. Furthermore, since the resistance is calculated based on the attenuation rate, the resonant vibration signal on the receiving side can be calculated without relying on the coupling coefficient.

[0051] In addition, such as Figure 6 and Figure 7 As shown, detector 300B can have multiple resonator circuits, such as in resonator circuit 302A and drive circuit 304A driving resonator circuit 302A, and resonator circuit 302B and drive circuit 304B driving resonator circuit 302B resonating at a frequency different from that in resonator circuit 302A. Detector 300B can use multiple resonator circuits connected in parallel to unit 301 to obtain resonant current attenuation characteristics in multiple different frequency bands with a relatively simple circuit configuration, such as frequencies in the range below 5MHz or frequencies in the range above 10MHz. In detector 300B, resonator circuit 302B includes a resonant capacitor C2 connected in series with inductor L1, a resistor R21 connected in parallel with resonant capacitor C2, and a semiconductor switch S2 connected in series with inductor L1. Furthermore, the resonator circuit 302B is driven by the drive circuit 304B, which turns on the semiconductor switch S2 via the drive capacitor Cx2 connected in parallel to the single cell 301 through the diode Dx2 and via the buffer BUF2 which provides power from the drive capacitor Cx2.

[0052] also, Figure 9 Another configuration example of an echo sensor 303 and a logic calculator 306 is shown, where the logic calculator 306 calculates the attenuation rate based on the damped waveform obtained from the resonator. For example, instead of using diodes to perform envelope rectification, a peak hold circuit can be used for the damped oscillation waveform, thereby enabling the acquisition of the voltage difference required to calculate the attenuation rate. Because the resonant frequency is fixed by L and C, and the peak time of the damped oscillation can be predicted in advance, for example, the peak hold circuit can be operated to hold the peak values ​​at the second and fifth maximum points, thereby enabling the acquisition of the voltage at both maximum points. Alternatively, by using a high-speed ADC, the entire damped oscillation waveform can be acquired and used to calculate the attenuation rate.

[0053] Inductors L1 and L2 can be closed magnetic circuit transformers with magnetic component M covering inductors L1 and L2, such as... Figure 10 As shown in Figure A, it can be an open magnetic circuit transformer with an exposed side surface, such as... Figure 10As shown in B, or it could be a wireless transformer that isolates inductors L1 and L2 from each other, such as... Figure 10 As shown in Figure C, appropriate options can be selected based on the configuration of detector 300 and controller 310.

[0054] The operating principle of the detection device 32 is described below. Figure 11 An example of an equivalent circuit model of a lithium-ion secondary battery is shown, including... Figure 11 A, Figure 11 B. Figure 11 C and Figure 11 D, Figure 11 A shows a mechanical structure model. Figure 11 B shows the complete model of the equivalent circuit. Figure 11 C shows a simplified equivalent circuit. Figure 11 D shows the equivalent circuit model corresponding to the high-frequency function. Figure 12 This shows the relationship between frequency and the real part of impedance under degraded conditions. Figure 13 An example illustrating the resonant current decay characteristics is shown. Specifically, Figure 11 D shows the equivalent circuit obtained as a result of extracting the parameters that dominate at high frequencies from its components. Table 1 shows a list of notes related to the elements. Figure 12 Showing the use Figure 11 The impedance characteristics calculated using the equivalent circuit model in expression (1) are shown. One degradation mode of lithium-ion secondary batteries is the deposition of lithium metal inside the battery; as the amount of metal deposition increases, the battery may become unsafe. The three important states of lithium-ion secondary batteries include the initial battery, the lithium deposition-degraded battery, and the SEI (shell layer) deposition-degraded battery. For example... Figure 12 As shown in region A1, it can be confirmed that in the range below 5 MHz, particularly around 1 MHz, the real part of the impedance decreases with increasing lithium deposition. On the other hand, in this frequency region, it can be confirmed that the real part of the impedance increases in SEI-degraded cells compared to the initial cell. In other words, based on whether the real part of the impedance decreases or increases, it is possible to clearly distinguish whether the cell degradation is due to lithium deposition or capping layer deposition. Furthermore, it can be confirmed that in the range above 10 MHz, particularly in region A2 around 20 MHz, the impedance increases with increasing SEI deposition. In other words, in this frequency region, the effect of SEI deposition degradation can be considered greater than that of lithium deposition degradation. Although Figure 12 The calculation results obtained using expression (1) are shown, but it can be confirmed that these results are correct because the trend indicated by the measurement results obtained using the 18650 lithium-ion secondary battery is consistent with... Figure 12 The waveforms shown have the same trend.

[0055] The detector 300 is characterized by its ability to easily and accurately measure the real part of the high-frequency impedance in a short period of time using an on-board method. Figure 13 Showing has Figure 12 A representative operational example of a lithium-ion secondary battery configuration is shown below. At a certain point in time, a step-on signal is input from the controller 310, which acts as the BMU, via isolator 305. In response to this signal, drive circuit 304 uses the power accumulated in drive capacitor Cx1, which is charged through cell 301, to drive semiconductor switch S1, thereby turning on semiconductor switch S1 in resonator circuit 302. When semiconductor switch S1 is turned on, cell 301 charges resonant capacitor C1 to the voltage of cell 301, while oscillating at the resonant frequency designed in inductor L1 and resonant capacitor C2. The oscillation in this resonant operation is suppressed due to the resistive component included in the resonant path, namely the battery resistance Rbat included in cell 301 relative to a specific frequency. Specifically, since the attenuation rate varies with the magnitude of the internal impedance of cell 301, the battery resistance Rbat can be calculated based on the attenuation rate. To perform this calculation, the signal waveform detected by pickup coil L2 is rectified on the diode bridge of rectifier circuit 308 to obtain the oscillation envelope. The battery resistance Rbat can be calculated based on the voltage values ​​Venv1 and Venv2 at multiple time points (t1 and t2) of the envelope.

[0056] The expressions (2) and (3) shown below are expressions for the resonant current flowing through inductor L1 and basic expressions for calculating the battery resistance Rbat based on the envelope output waveform obtained from pickup coil L2. Expression (2) is an expression for the current flowing through the circuit of detector 300 when semiconductor switch S1 is closed at time point t = 0. Expression (3) is an expression for determining the battery resistance Rbat based on the envelope voltages Venv1 and Venv2 at time points t1 and t2. According to expression (2), it is clear that the attenuation of the envelope changes at the resistance Rbat, which acts as the shoulder value exp, and it is clear that its value can be measured based on the ratio between the two envelope values. The advantage of this method is that detector 300 can be driven using the battery's own power (i.e., voltage V), the configuration is simple, and the battery voltage V varies according to the state of charge, not depending on its voltage change. This is evident from the fact that the battery voltage V is not included in expression (3). Furthermore, the method is characterized by the ability to obtain the resistance relative to a specific resonant frequency designed in the inductor L1 and the resonant capacitor C1 in a precise manner, by the minimal electrical power consumed due to the single-shot operation, and by the ability to obtain the two voltage values ​​Venv1 and Venv2 through a universal sample-and-hold circuit, and therefore its advantage lies in the fact that there are virtually no problems with practical implementation.

[0057] In detector 300, the estimation accuracy depends on the design of the resonator circuit 302. First, the resonant operation needs to generate damped vibration, and the battery resistance Rbat needs to be dominant in the resistance component of the system. When the parasitic resistance of inductor L is defined as RL, RL < Rbat is preferred. As an example, when the resonant frequency band is set to 1 MHz, by setting the resonant sharpness Q to about 50 to 100, changes in battery resistance in the range of tens to hundreds of mΩ can be detected. This can be achieved by designing the resistance of a reactor equipped with a pickup coil to a low value. Furthermore, the resistance decrease caused by lithium deposition can be captured in a frequency band around 1 MHz, which is high enough that, for example, diffusion and reaction cannot follow, is measurable, and is lower than the frequency at which the orientational polarization effect occurs. Furthermore, in the detection device 32, attenuation characteristics are measured when narrowed down to a specific frequency, so a more direct, simpler ultra-miniature sensor circuit can be implemented on-board in the cell 301.

[0058] [Expression 1]

[0059]

[0060] [Expression 2]

[0061]

[0062]

[0063] [Table 1]

[0064]

[0065]

[0066] (Detection Method)

[0067] The following description relates to the operation of the detection device 32 according to this embodiment with such a configuration, specifically relates to a detection method executed by the detection device 32 for detecting the state of a lithium-ion secondary battery. The detection method may for example comprise: an output step of applying at least one specific frequency vibration to the lithium-ion secondary battery, measuring the attenuation characteristic of the resonant current, and outputting the attenuation characteristic as a detection signal; and a detection step of detecting lithium deposition and / or the presence of impurity metal inside the lithium-ion secondary battery by using the attenuation characteristic detection signal obtained in the output step. In the detection step, for convenience, lithium deposition is detected, and the case of detecting battery degradation will be mainly described.

[0068] Figure 14 is a flowchart showing a general overview of calculation processing for detecting the state of a cell implemented in the logic calculator 306 of the controller 310, and includes Figure 14 A and Figure 14 B, Figure 14 A shows the calculation process in frequency region A1. Figure 14 B illustrates the calculation processing in frequency region A2. For example, by implementing logic capable of measuring two frequencies when necessary, the logic calculator 306 performs correction calculations to adjust the temperature characteristics of the diodes used for rectification, as well as calculations of degradation and deposition amounts. Furthermore, the results can be recorded in a database in a traceable manner, thereby identifying the transitions and factors of degradation and deposition. Additionally, using the same principle, resistance changes occurring when impurity metals are introduced into the battery can be detected, and this information can be used in the manufacturer's server 20 to improve quality during production processing. Figure 14 As shown in Figure A, the logic calculator 306 performs the following process: It obtains the battery resistance Rbat by measuring the resonant current decay characteristics in frequency region A1, and determines the lithium metal deposition amount based on the resistance change using a pre-acquired MAP (S10). For example, the MAP can be set based on the relationship between the resistance change and the lithium metal deposition amount. This relationship can be obtained empirically, for example, based on tests. Then, for example, the controller 310 provides a safety factor for the corresponding cell 301 based on the obtained lithium metal deposition amount. Or, as... Figure 14 As shown in B, after the calculation in step S10, the logic calculator 306 performs the following process: it obtains the battery resistance Rbat by measuring the resonant current decay characteristics in frequency region A2, and obtains the state of charge (SOC) based on the resistance change using a pre-acquired MAP (S20). For example, the MAP can be set based on the relationship between the resistance change and the state of charge (SOC). This relationship can be obtained empirically, for example, based on tests. Then, for example, the controller 310 provides the safety factor and state of charge (SOC) for the corresponding cell 301.

[0069] The following describes the more detailed processing of the detection device 32. Figure 15 This is a flowchart illustrating an example of a detection processing routine executed by the main calculator 307 of the detection device 32. For example, this routine is repeated after each predetermined time period (e.g., 1 minute or 1 hour). The main calculator 307 executes this routine using the circuit configuration of the detector 300 and the controller 310. As a specific example, the following description relates to an example in which... Figure 7The detector 300B, equipped with resonator circuits 302A and 302B, measures the battery resistance Rbat in frequency regions A1 and A2. When this routine begins, the main calculator 307 obtains the temperature T of the cell 301 from the temperature sensor 311 (S100) and determines whether processing has been performed on all frequencies (S110). If processing has not yet been performed on all frequencies, the resonator circuit n is set to (n+1) (S120). In this case, n is set to 0 as the initial value. For example, in step S120, the main calculator 307 sets the resonator circuit 302A to an available mode.

[0070] Subsequently, the main calculator 307 outputs the drive signal Vsn to the semiconductor switch S1 of the detector 300 via the isolator 305 (S130). The resonator circuit 302 measures the attenuation characteristics of the resonant current resonating in frequency region A1. Then, the main calculator 307 outputs the time periods S / H1 and S / H2 (S140) for which the voltage values ​​Venv1 and Venv2 are to be measured, and obtains the voltage values ​​Venv1 and Venv2 sampled and held according to the detection signal output from the wave sensor 303 from the logic calculator 306 (S150). Subsequently, the main calculator 307 determines whether the voltage values ​​have been averaged a predetermined number of times (S160). If the voltage values ​​have not been averaged a predetermined number of times, the main calculator 307 performs the processing forward from step S110. In other words, in step S120, the subsequent resonator circuit 302B is set up to measure the attenuation characteristics of the resonant current resonating in frequency region A2, and the voltage values ​​Venv1 and Venv2 are obtained from the logic calculator 306.

[0071] Conversely, if the voltage values ​​have been averaged a predetermined number of times in step S160, the main calculator 307 performs temperature correction on the voltage values ​​Venv1 and Venv2 obtained from the logic calculator 306 at temperature T (S170), determines the battery resistance Rbat based on the corrected voltage values ​​Venv1 and Venv2, further calculates the average resistance Rn (S180), and performs processing forward from step S110. When processing for all frequencies is complete in step S110, the main calculator 307 stores the average resistance Rn in a storage unit (S190), calculates and outputs the lithium deposition amount X and the capping layer amount Y (S200). The lithium deposition amount X and the capping layer amount Y can be calculated in steps S10 and S20.

[0072] Subsequently, the main calculator 307 determines whether over-deposition is detected based on whether the deposition amount X exceeds a predetermined allowable range (S210). This allowable range can be set to a value obtained by empirically determining the amount of lithium metal deposition that affects the charging and discharging of the monomer 301. If over-deposition is not detected, the main calculator 307 determines whether a capping layer deposition state exceeding the allowable range is detected based on whether the capping layer amount Y exceeds a predetermined allowable range (S220). This allowable range can be set to a value obtained by empirically determining the amount of capping layer deposition that affects the charging and discharging of the monomer 301. If no degradation due to capping layer deposition is detected, the output of the monomer 301 is limited according to the degree of degradation (S240), and the routine ends.

[0073] Conversely, when excessive deposition is detected in step S210 or degradation due to capping layer deposition is detected in step S220, the main computer 307 performs an emergency shutdown process (S230) on the corresponding cell 301 and terminates the routine. Therefore, the battery system 30 stops the use of cells 301 with lithium deposition that could potentially cause a short circuit and appropriately limits output in response to capacity degradation, thereby maintaining the usability of cells 301.

[0074] The correspondence between the components according to this embodiment and the components according to this disclosure is clarified below. The single cell 301 according to this embodiment corresponds to the lithium-ion secondary battery according to this disclosure, the detection device 32 corresponds to the detection device, the manufacturer server 20 and the management server 25 correspond to the management device, the detector 300 corresponds to the detector, and the controller 310 corresponds to the controller. Furthermore, the resonator circuit 302 corresponds to the resonator circuit, the wave sensor 303 corresponds to the wave sensor, the drive circuit 304 corresponds to the drive circuit, the isolator 305 corresponds to the isolator, the logic calculator 306 corresponds to the logic calculator, and the main calculator 307 corresponds to the main calculator. In this embodiment, the operation of the detection device 32 is described to demonstrate an example of the detection method according to this disclosure.

[0075] The detection device 32 according to the above embodiment can detect the degradation of lithium-ion secondary batteries using a simpler configuration and easier technology. The reason why the present invention exhibits this advantage is as follows. For example, after applying a specific frequency vibration to the lithium-ion secondary battery using the resonator circuit 302, the battery resistance Rbat can be estimated based on the resonant current decay characteristics. Furthermore, for example, the internal state of the battery, such as the amount of lithium deposition and the formation of the capping layer, can be estimated based on the battery resistance Rbat. The detection device 32 can use a detector 300 with a simple resonator circuit 302 capable of detecting the state of individual cells in an on-board manner when using a lithium-ion secondary battery; therefore, the degradation of the lithium-ion secondary battery can be detected using a simpler configuration and easier technology. Furthermore, the detection device 32 can estimate the percentage of metal deposition relative to the degradation state using the battery resistance Rbat determined in two frequency regions A1 and A2. Specifically, the amount of lithium metal deposition inside the battery can be estimated based on the change in the real part of the impedance in frequency region A1. Furthermore, the amount of capping layer deposition can be estimated using the battery resistance Rbat determined in frequency region A2, and this can be combined with the amount of lithium metal deposition to more accurately estimate lithium loss, i.e., the degradation of lithium-ion secondary batteries.

[0076] Furthermore, the detection device 32 is capable of capturing the resistance drop caused by lithium deposition in a frequency band around 1 MHz. This frequency is high enough that diffusion and reaction cannot be followed or measured, and is below the frequency at which orientation polarization effects occur. Moreover, by narrowing down to a specific frequency using relatively simple circuitry, such as that including a resonator circuit 302, a wave sensor 303, a drive circuit 304, an isolator 305, and a logic calculator 306, a simple, extremely small sensor circuit can be implemented in the battery system 30. The detection device 32 can estimate the amount of lithium deposition that forms non-destructively inside the lithium-ion secondary battery and can shut down the cell 301 during its use with reference to permissible ranges. Furthermore, the amount of coating layer can be estimated, and the output can be limited based on the amount of coating layer, thereby ensuring safer use of the cell 301.

[0077] In any case, this disclosure is not limited to the above embodiments, and can be implemented in various modes within the technical scope of this disclosure.

[0078] For example, Figure 16 Various modes of the detection device 32 are shown, including Figure 16 A, Figure 16 B. Figure 16 C Figure 16 D and Figure 16 E, Figure 16 A shows the analog interface testing device 32A. Figure 16 B shows the analog interface and ID management detection device 32B. Figure 16C shows a digital interface testing device 32C. Figure 16 D shows the wireless interface detection device 32D, and Figure 16 E indicates the battery independent detection device 32E. Figure 16 An implementation example of detector 300 and controller 310 is shown. In detection device 32B, detector 300 is equipped with RFID 312, which provides identification information ID for unit 301 to facilitate identification, and controller 310 is equipped with RFID 313, so that the detection result and identification information ID of unit 301 can be output correspondingly. Therefore, unit 301 is easily identifiable in manufacturer server 20, management server 25, and display unit of detection device 32, which acts as the output destination. In detection device 32C, detector 300 is equipped with ID tag 314 and digital interface (I / F) 315, so that information can be exchanged with main calculator 307 via digital I / F 315. In detection device 32C, the controller is simplified, while the detector and battery have higher functionality. In detection device 32D, detector 300 is equipped with wireless I / F 316, so that information can be exchanged wirelessly with main calculator 307. In the detection device 32E, the controller 310 function is provided within the detector 300, and the detector 300 includes a sequencer 318 and a shutdown circuit 319. Furthermore, a single cell 301 is connected in series with an irreversible switch 320. The sequencer 318 periodically outputs a drive signal to the drive circuit 304. When the shutdown circuit 319 determines, based on information obtained from the logic calculator 306, that the single cell 301 is in an abnormal state, the shutdown circuit 319 turns off the irreversible switch 320 to stop the use of the single cell 301. The detection device 32E can similarly detect the degradation of lithium-ion secondary batteries by using a simplified configuration and easier technology.

[0079] While the above-described embodiments relate to a battery system 30 equipped with a single cell 301, this embodiment is not particularly limited thereto. The detection device 32 can be used in a battery system 30 having cells 301 connected in series, or it can be used in a battery system 30 having cells 301 connected in parallel. Figure 17 An example of a detection device 32F having a single unit 301 connected in series is shown. Figure 18 An example of a detection device 32G with individual units 301 connected in parallel is shown. In the detection device 32F, a controller 310 is provided with a multiplexer 401. The multiplexer 401 performs multiplexing, thereby driving each detector 300 and acquiring the detection signal therefrom.

[0080] Figure 19An example of a detection device 32H for a battery system equipped with a battery module consisting of multiple cells 301 is shown. In the detection device 32H, detectors 300H are implemented in corresponding cells 301 of the battery module, and a controller 310 acting as a BMU performs multiplexing, thereby enabling easy measurement of the state of each cell 301. For example, the detection device 32H can be used in a battery system in an electric vehicle equipped with multiple battery modules. The detection device 32H connects detectors 300H to corresponding cells 301, connects a controller 310H acting as a BMU to multiple detectors 300H, collects signals from the controller 310H using a higher-level ECU 410, and stores a large amount of data storage results traceable by using an external communication device. The ECU 410 includes a storage device 411 and an external communication device 412, and can store the detection results of the detection device 32H and provide the detection results, for example, to an external database 413. By providing a threshold for the detected values ​​within the system, battery protection operations (controls), including suppressing the system output, can be performed in the ECU 410. like Figure 1 As shown, measurement data transmitted from, for example, the battery of an electric vehicle, using the system, is stored in storage units B and D along with other usage records (e.g., travel data). The management server 25, which manages storage units 27 and 28, is managed by a management unit 26 with a computing system and can provide information to the battery system 30, for example, regarding recovery, replacement, and maintenance, using the usage records. Furthermore, the assembly manufacturer using the manufacturer server 20 can obtain the test results from the testing device 32, and the management unit 21 with the computing system can use these test results to improve quality.

[0081] Figure 20 An example of a standalone leased data storage system is shown. Figure 20 and Figure 21 Examples of services that can be provided by the manager are shown below. For instance, by setting the management algorithm for managing leaseable batteries to a computing system, a leasing service capable of managing safe use can be provided. Figure 20 As shown, the battery leasing system 500 obtains information from the customer regarding customer ID, purpose of use, usage time, service point, and usage location. Furthermore, the battery leasing system 500 obtains the battery ID, state of charge (SOC), charge level, lithium deposition level, degradation status, and usage location for each used battery module. Then, the battery leasing system 500 performs pricing, customer matching, maintenance, and safety management of the battery modules to be leased, thereby enabling the appropriate battery modules to be leased to customers.

[0082] Figure 21An example of a standalone sales data storage system is shown. For instance, by setting up algorithms for managing degradation and safety factors in a computational system, a resale service for reusable batteries can be established. Figure 21 As shown, the battery recycling system 510 obtains information from the customer regarding customer ID, purpose of use, usage time, service point, and usage location. Furthermore, the battery recycling system 510 obtains the battery ID, state of charge (SOC), charge level, lithium deposition level, degradation status, and usage location for each used battery module. Then, the battery recycling system 510 performs pricing, customer matching, maintenance, and safety management of the battery modules to be sold and reused, thereby enabling the sale of suitable reusable battery modules to customers.

[0083] While the above embodiment relates to a detection device 32 having a circuit designed with only the real part of impedance considered, this embodiment is not particularly limited thereto. The circuit can be designed with the imaginary part of impedance considered. Figure 22 Another example of the 300C detector is shown. Figure 23 Another example of another detector, the 300D, is shown. Figure 24 This shows another example of a 300E detector. Figures 22 to 24 In each of the detectors 300C to 300E shown, in addition to wave sensor 1, wave sensor 2 is also connected in parallel to unit 301, and the detection signal is output from wave sensor 2 to controller 310 via buffer BUF2. Figure 23 The detector 300D includes a high-pass filter HPF1 connected in series with the pickup coil L2, a high-pass filter HPF2 connected in series with the unit 301, and an XOR gate XOR1 connected to the high-pass filter HPF1 via a buffer BUF4 and connected to the high-pass filter HPF2 via a buffer BUF5. The XOR gate XOR1 is connected to the controller 310 via a low-pass filter LPF1 and outputs a voltage Vf3 to the controller 310. In addition to the configuration of the detector 300D, Figure 24 The detector 300E provides a phase difference by causing the end of the high-pass filter HPF1 to bifurcate, and outputs voltages Vsinf3 and Vcosf3 to the controller 310 via low-pass filters LPF1 and LPF2. This is achieved by using... Figures 22 to 24 The configuration shown can further improve detection accuracy.

[0084] This application claims priority to Japanese Patent Application No. 2021-100855, filed on June 17, 2021, the entire contents of which are incorporated herein by reference.

[0085] Industrial applicability

[0086] The testing apparatus, management equipment, and testing methods disclosed in this specification are applicable to the technical field of detecting the state of lithium-ion secondary batteries.

[0087] List of reference numerals

[0088] 10 Battery Management System

[0089] 20 Manufacturer Servers

[0090] 21 Management Units

[0091] 25 Management Server

[0092] 26 Management Units

[0093] 27 storage units

[0094] 28 storage units

[0095] 30 Battery System

[0096] 31 Load

[0097] Detection devices 32, 32A to 32H

[0098] Detectors 300, 300A to 300H

[0099] 301 monomer

[0100] 302A and 302B resonator circuits

[0101] 303, 303A, 303B wave sensors

[0102] 304, 304A, 304B drive circuits

[0103] 305 Isolator

[0104] 306 Computational Logic

[0105] 307 Main Calculator

[0106] 308 rectifier circuit

[0107] 309 filter

[0108] 310, 310H controllers

[0109] 311 Temperature Sensor

[0110] 312 RFID

[0111] 313 RFID

[0112] 314 ID tags

[0113] 315 Digital I / F

[0114] 316 Wireless I / F

[0115] 318 Sequencer

[0116] 319 Shutdown Circuit

[0117] 320 Irreversible Switch

[0118] 401 Multiplexer

[0119] 410 ECU

[0120] 411 Storage device

[0121] 412 External communication device

[0122] 413 Database

[0123] 500 Battery Rental System

[0124] 510 Battery Recycling System

[0125] Frequency regions A1 and A2

[0126] BUF1 to BUF5 buffers

[0127] HPF1 and HPF2 high-pass filters

[0128] LPF1 and LPF2 low-pass filters

[0129] C1 Resonant capacitor

[0130] Cf filter capacitor

[0131] Cx1 drive capacitor

[0132] Dx1 driving diode

[0133] Dr1 to Dr4 rectifier diodes

[0134] L1 inductor

[0135] L2 Pickup Coil

[0136] M magnetic component

[0137] R1 resistor

[0138] Rf filter resistor

[0139] Rbat battery resistor

[0140] S1 and S2 are semiconductor switches.

Claims

1. A detection device for detecting the state of a lithium-ion secondary battery, the detection device comprising: The detector includes at least one resonator circuit and a driving circuit. The resonator circuit applies vibration at at least one specific frequency to the lithium-ion secondary battery. The driving circuit drives the at least one resonator circuit. The detector measures the attenuation characteristics of at least one resonant current of the at least one resonator circuit driven by the driving circuit and outputs the measured attenuation characteristics as a detection signal. in, One end of the at least one resonator circuit is connected to one terminal of the lithium-ion secondary battery, and the other end of the at least one resonator circuit is connected to the other terminal of the lithium-ion secondary battery; and A controller that detects the presence of lithium deposits and / or impurity metals inside the lithium-ion secondary battery by outputting the detection signal from the detector.

2. The detection device according to claim 1, wherein, The controller detects the presence of lithium deposition and / or the impurity metal by estimating the battery resistance using voltage values ​​at multiple time points as the decay characteristics of the resonant current.

3. The detection device according to claim 1 or 2, wherein, The detector includes the at least one resonator circuit, a wave sensor that rectifies the signal output from the resonator circuit and outputs the signal as the detection signal, and the driving circuit that drives the resonator circuit.

4. The detection device according to claim 3, wherein, The detector includes a closed circuit, the wave sensor, and the drive circuit. The closed circuit consists of a resonator circuit, a resonant capacitor, and a semiconductor switch. The resonator circuit includes an inductor equipped with a pickup coil connected in parallel to the lithium-ion secondary battery. The resonant capacitor is connected in series to the inductor. The semiconductor switch is connected in series to the inductor. The wave sensor has a pickup coil, a rectifier circuit, and a filter. The pickup coil detects the resonant current flowing through the inductor. The rectifier circuit consists of a diode bridge connected to the pickup coil. The filter includes a capacitor and a resistor, filters the rectified waveform, and outputs a detection signal. The drive circuit turns on the semiconductor switch via a drive capacitor connected in parallel to the lithium-ion secondary battery and via a buffer powered from the drive capacitor.

5. The detection device according to claim 4, wherein, The controller includes a logic calculator, an isolator, and a main calculator. The logic calculator has at least one sample-and-hold circuit and calculates the detection signal output from the filter. The isolator has a series capacitor and outputs a drive signal to the drive circuit. The main calculator outputs a drive signal to the isolator and receives the detection signal from the logic calculator.

6. The detection device according to claim 1 or 2, wherein, When the frequency vibration applied by the resonator circuit is in the range below 5MHz, the controller detects the presence of lithium deposits and / or impurity metals inside the lithium-ion secondary battery based on the reduction of the real part of the impedance.

7. The detection device according to claim 1 or 2, wherein, When the frequency vibration applied by the resonator circuit is in the range of 10 MHz or higher, the controller detects the capping layer formed on the electrode based on the increase of the real part of the impedance.

8. The detection device according to claim 1 or 2, in, The lithium-ion secondary battery includes multiple individual cells connected in parallel or series to the detector, and The controller is connected to a plurality of the detectors and detects the presence of the lithium deposit and / or the impurity metal inside any one of the individual monomers.

9. The detection device according to claim 1 or 2, wherein, The detector has identification information for identifying the connected lithium-ion secondary battery, and outputs the detection signal and the identification information in a corresponding manner.

10. The detection device according to claim 1 or 2, in, The lithium-ion secondary battery is connected in series with an irreversible switch, and When the controller determines that the lithium-ion secondary battery is in an abnormal state, the controller shuts off the irreversible switch.

11. A management device for managing lithium-ion secondary batteries based on information obtained from the detection apparatus according to claim 1 or 2, the management device comprising: The management unit utilizes the lithium-ion secondary battery by using detection results of lithium deposition inside the lithium-ion secondary battery output from the controller, while limiting its use based on the remaining volume of active lithium.

12. A management device for managing lithium-ion secondary batteries based on information obtained from the detection apparatus according to claim 1 or 2, the management device comprising: A management unit uses detection results from the controller regarding the lithium deposition inside the lithium-ion secondary battery to quantify the residual value of the lithium-ion secondary battery based on the remaining volume of active lithium, the residual value including remaining usage time.

13. A management device for managing lithium-ion secondary batteries based on information obtained from the detection apparatus according to claim 1 or 2, the management device comprising: The management unit calculates and outputs the calculated distribution value by using the detection results of the lithium deposition inside the lithium-ion secondary battery output from the controller.

14. A method for detecting the state of a lithium-ion secondary battery, the method comprising: The output step is used to apply at least one specific frequency vibration to the lithium-ion secondary battery through at least one resonator circuit. While one end of the at least one resonator circuit is connected to one pole of the lithium-ion secondary battery and the other end of the at least one resonator circuit is connected to the other pole of the lithium-ion secondary battery, the attenuation characteristic of at least one resonant current of the at least one resonator circuit driven by the driving circuit is measured, and the measured attenuation characteristic is output as a detection signal. as well as The detection step is used to detect the presence of lithium deposits and / or impurity metals inside the lithium-ion secondary battery by using the detection signal output in the output step.

Images