Battery monitoring device

Abstract

To provide a battery monitoring device that can ensure the reliability of a precipitation amount detection unit that calculates the amount of lithium precipitation.SOLUTION: A battery monitoring device 20 monitors the amount of lithium precipitation in a lithium ion battery. The battery monitoring device 20 comprises: a storage unit 51 that stores a change over time of the amount of lithium precipitation as one of the histories of use of the lithium ion battery or one of the histories of manufacture of the lithium ion battery; and an abnormality identification unit 544 that, when an abnormality occurs in the lithium ion battery, identifies the cause of occurrence of the abnormality on the basis of the use history and the manufacture history.SELECTED DRAWING: Figure 24

Description

Technical Field

[0001] The present disclosure relates to a battery monitoring device.

Background Art

[0002] Conventionally, as a technique for diagnosing an internal short circuit of a lithium-ion battery, there is known one including a short circuit circuit including a switch, a resistor, a coil, etc. that short-circuit both ends of the lithium-ion battery (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the inventors of the present invention focused on the fact that there is a correlation between the amount of lithium precipitation in a lithium-ion battery and the behavior of current and voltage when both ends of the lithium-ion battery are short-circuited, and considered estimating the amount of lithium precipitation from the behavior.

[0005] However, the internal resistance of a lithium-ion battery is about several mΩ to several hundred mΩ, and it is easily affected by disturbances. It was found that it is difficult to accurately obtain the amount of lithium precipitation by the above estimation method and it lacks reliability. This was found as a result of the inventors' intensive studies.

[0006] One object of the present disclosure is to provide a battery monitoring device capable of ensuring the reliability of a precipitation amount detection unit that calculates the amount of lithium precipitation. Another object of the present disclosure is to provide a battery monitoring device capable of appropriately detecting the amount of lithium precipitation.

Means for Solving the Problems

[0007] The invention described in claim 1 is, A battery monitoring device for monitoring the amount of lithium deposited in a lithium-ion battery, A deposition amount detection unit (37) that calculates the lithium deposition amount using the output of a sensor installed in the storage battery, The time-dependent changes in the amount of lithium deposited during the manufacturing process of lithium-ion batteries are stored as part of the manufacturing history, and the time-dependent changes in the amount of lithium deposited during the use of lithium-ion batteries are stored as part of the usage history. The memory unit (51) that stores information, When a lithium-ion battery malfunctions, based on both the usage history and manufacturing history stored in the memory unit, It includes an abnormality identification unit (544) that identifies the cause of the abnormality.

[0008] With this configuration, the amount of lithium deposition can be detected non-destructively and quickly, allowing for inspection of the lithium deposition state. In particular, since the sensor for detecting lithium deposition is installed on the battery, it is possible to detect the lithium deposition state regardless of time or location. Furthermore, by storing the time change in the amount of lithium deposition as one of the usage history or manufacturing history of the lithium-ion battery in the memory unit, it is possible to clearly understand when lithium deposition occurred. This has the advantage of clearly identifying who is responsible for lithium deposition.

[0009] The invention described in claim 2 is, When the amount of lithium deposited increases beyond a predetermined threshold, the battery is heated by a heating element (HM) that raises the temperature of the battery.

[0010] According to this method, the lithium-ion battery is heated at the moment when the amount of lithium deposited increases, thereby appropriately suppressing the increase in lithium deposition, and thus the lithium-ion battery can be used in a safe and highly efficient manner.

[0011] The reference numerals in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described later. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing a battery pack to which the battery monitoring device according to the first embodiment is applied. [Figure 2] It is an explanatory diagram for explaining a lithium-ion battery. [Figure 3] It is a schematic configuration diagram of a battery management unit including a battery monitoring device. [Figure 4] It is an explanatory diagram for explaining a battery monitoring device. [Figure 5] It is an explanatory diagram for explaining a deposition amount detection unit included in a battery monitoring device. [Figure 6] It is an explanatory diagram for explaining a method of calculating the lithium deposition amount. [Figure 7] It is an explanatory diagram for explaining a method of obtaining a parasitic resistance value. [Figure 8] It is an explanatory diagram for explaining the flow of calculating the lithium deposition amount. [Figure 9] It is an explanatory diagram for explaining the diagnosis of the deposition amount detection unit by a diagnosis unit. [Figure 10] It is an explanatory diagram for explaining a method of calculating the volume ratio SOH of a battery. [Figure 11] It is a timing chart showing the output changes of various sensors before and after the occurrence of an abnormal heat generation phenomenon. [Figure 12] It is an explanatory diagram for explaining the flow of control processing executed by a battery monitoring device. [Figure 13] It is a schematic configuration diagram of a battery management system including a battery monitoring device. [Figure 14] It is a schematic configuration diagram of a charging system including a battery monitoring device. [Figure 15] It is an explanatory diagram for explaining the current and voltage during charging of a battery module in a charging system serving as a comparative example of the first embodiment. [Figure 16] It is an explanatory diagram for explaining the flow of control processing executed by a battery monitoring device at the start of charging of a battery module. [Figure 17] It is an explanatory diagram for explaining the flow of control processing executed by a charger. [Figure 18] It is an explanatory diagram for explaining the flow of control processing executed by a battery monitoring device during charging of a battery module. [Figure 19] It is an explanatory diagram for explaining the current and voltage during charging of a battery module in the charging system of the first embodiment. [Figure 20] It is a schematic configuration diagram of a battery evaluation system. [Figure 21] It is a schematic block diagram for explaining the value calculation and application proposal of a battery module by a battery evaluation system. [Figure 22] It is an explanatory diagram for explaining the rebuilt information generated by the battery evaluation system. [Figure 23] It is an explanatory diagram for explaining the manufacturing process until a battery pack is mounted on a vehicle. [Figure 24] It is an explanatory diagram for explaining a part of the functions of a battery monitoring device according to the second embodiment. [Figure 25] It is an explanatory diagram for explaining the timing when lithium is deposited in a lithium-ion battery. [Figure 26] It is a schematic configuration diagram of a large-capacity power storage system according to the third embodiment. [Figure 27] It is an explanatory diagram for explaining the internal configuration of a large-capacity power storage system. [Figure 28] It is a schematic system configuration diagram of a large-capacity power storage system. [Figure 29] It is an explanatory diagram for explaining the temperature control of a large-capacity power storage system as a comparative example of the third embodiment. [Figure 30] It is an explanatory diagram for explaining the temperature control of a large-capacity power storage system according to the third embodiment. [Figure 31] It is an explanatory diagram for explaining a modified example of temperature control. [Figure 32] It is an explanatory diagram for explaining the appropriate timing for battery replacement. [Figure 33] It is an explanatory diagram for explaining the relationship between the charging rate, temperature, and lithium precipitation amount. [Figure 34] It is a schematic configuration diagram of a battery transport device according to the fourth embodiment. [Figure 35] It is a schematic system configuration diagram of a battery transport device. [Modes for carrying out the invention]

[0013] Embodiments of this disclosure will be described below with reference to the drawings. In the following embodiments, parts that are the same as or equivalent to those described in the prior embodiments will be denoted by the same reference numerals, and their descriptions may be omitted. Also, if only a part of a component is described in an embodiment, the components described in the prior embodiments can be applied to the other parts of that component. The following embodiments can be partially combined with each other, even if not explicitly stated, as long as it does not impede the combination. (First Embodiment) In this embodiment, first, an example of applying the battery monitoring device 20 and battery monitoring method of this disclosure to a battery management unit (hereinafter also referred to as BMU) of a vehicle equipped with a battery pack 1, which is a high-voltage battery, will be described with reference to Figures 1 to 13. After that, in this embodiment, a charging system BCS and a battery evaluation system BRS including the battery monitoring device 20 will be described.

[0014] [BMU] The BMU includes a battery pack 1 as shown in Figure 1. The battery pack 1 comprises a sealed container 11 that forms the outer shell, and inside the sealed container 11 are multiple battery modules BM, a battery monitoring device 20, and a battery ECU 100. The sealed container 11 is equipped with a high-pressure protection valve HPV to exhaust gas inside to the outside when the internal pressure rises. The battery pack 1 adjusts each battery module BM to an appropriate temperature using a temperature control device (not shown).

[0015] Multiple battery modules BM are power sources connected to electric motors and other electrical equipment for vehicle operation (not shown), supplying power to said electrical equipment. Multiple battery modules BM are electrically connected in series. Multiple battery modules BM are also battery packs in which multiple battery cells C are electrically connected in series. In this embodiment, a battery pack 1 with three battery modules BM is shown as an example, but the number of battery modules BM is not limited to this and can be any number. The number of battery cells C constituting the battery modules BM can also be any number. Note that some of the battery modules BM may be electrically connected in parallel. Hereafter, battery cells C and battery modules BM may simply be referred to as batteries. Note that the battery modules BM in this embodiment are rechargeable batteries including lithium-ion batteries.

[0016] Battery cell C is a rechargeable secondary battery. Battery cell C is composed of a lithium-ion battery. A lithium-ion battery is composed of a lithium iron phosphate (LFP) or nickel-manganese-cobalt (NMC) as the positive electrode material, as shown in Figure 2, and graphite as the negative electrode material. In addition, a lithium-ion battery is composed of an aluminum current collector on the positive electrode side and a copper current collector on the negative electrode side. A lithium-ion battery configured in this way has excellent charge-discharge cycle characteristics, but its electrode potential is very close to the lithium deposition potential, and lithium is easily deposited when it is charged.

[0017] As shown in Figure 3, the battery monitoring device 20 is electrically connected to each battery module BM via a connecting member 21. The connecting member 21 includes a flexible printed circuit board (FPC) with a wiring pattern printed on it. The battery monitoring device 20 comprises the same number of sensor units 30A, 30B, and 30C as each battery module BM, and the same number of monitoring modules 50A, 50B, and 50C as each battery module BM. Since the sensor units 30A, 30B, and 30C have the same basic configuration, they will be described collectively as sensor unit 30 rather than individually. Similarly, since the monitoring modules 50A, 50B, and 50C have the same basic configuration, they will be described collectively as monitoring module 50 rather than individually.

[0018] The sensor unit 30 detects the battery state of each battery module BM. As shown in Figure 4, the sensor unit 30 includes a temperature sensor 31, a current sensor 32, a voltage sensor 33, a strain sensor 34, a gas sensor 35, a pack pressure sensor 36, a deposition amount detection unit 37, and a coating detection unit 38. At least some of the various sensors constituting the sensor unit 30 are mounted on a flexible printed circuit board (FPC). It is not necessary for all of the various sensors constituting the sensor unit 30 to be mounted on a flexible printed circuit board (FPC). However, it is desirable for the temperature sensor 31, strain sensor 34, and gas sensor 35 to be mounted on a flexible printed circuit board (FPC) because they should be located near the battery cell C.

[0019] The temperature sensor 31 is a sensor that detects the battery temperature of a lithium-ion battery. As shown in Figure 1, multiple temperature sensors 31 are mounted on the flexible printed circuit board (FPC). The flexible printed circuit board (FPC) has the same number of temperature sensors 31 as the battery cells C, or slightly fewer than the number of battery cells C, mounted on it so that the battery temperatures of all lithium-ion batteries constituting the battery module BM can be determined. In this case, the means for estimating the battery temperature also functions as the temperature sensor 31.

[0020] The current sensor 32 is a sensor that detects the current flowing through the battery module BM. If each battery module BM is electrically connected in series, one current sensor 32 is sufficient for the battery pack 1.

[0021] In addition to detecting the cell voltage of each battery cell C, the voltage sensor 33 can also detect the voltage of the battery module BM as a block voltage. The voltage sensor 33 can be configured, for example, as a flying capacitor type circuit that sequentially charges a capacitor with the cell voltage of each battery cell C and detects the voltage across the terminals of the capacitor as the cell voltage.

[0022] The strain sensor 34 is a sensor that detects the strain in each battery cell C caused by gas generation inside each battery cell C. Note that the strain in the battery cells C may be detected by other sensors, such as ultrasonic sensors, instead of the strain sensor 34.

[0023] The gas sensor 35 is a sensor for detecting gas leaks from each battery cell C. The gas sensor 35 is configured to detect at least one of hydrogen, carbon monoxide, carbon dioxide, and hydrogen fluoride, which are generated when a malfunction occurs in the lithium-ion battery.

[0024] The internal pack pressure sensor 36 is a sensor that detects the pressure inside the sealed container 11 of the battery pack 1 as the internal pack pressure. The internal pack pressure sensor 36 is composed of, for example, an atmospheric pressure range type pressure sensor that uses atmospheric pressure as a reference.

[0025] The deposition amount detection unit 37 is a device that detects lithium deposition in a lithium-ion battery. The deposition amount detection unit 37 estimates the lithium deposition amount from the behavior of the current and voltage when the ends of the lithium-ion battery are short-circuited, by utilizing the correlation between the amount of lithium deposition in the lithium-ion battery and the behavior of the current and voltage when both ends of the lithium-ion battery are short-circuited.

[0026] As shown in Figure 5, the deposition amount detection unit 37 includes a short-circuit circuit 371 that temporarily short-circuits both ends of the lithium-ion battery to discharge it, and a calculator 372 that estimates the lithium deposition amount based on the behavior of the current and voltage when the lithium-ion battery is short-circuited by the short-circuit circuit 371. The short-circuit circuit 371 is mounted on a flexible printed circuit board (FPC). The calculator 372 is mounted on the monitoring module 50.

[0027] Although not shown in the diagram, the short circuit 371 includes a short-circuit switch, a coil, and a capacitor for short-circuiting the terminals of the lithium-ion battery. The internal resistance of the lithium-ion battery, the coil of the short circuit 371, and the capacitor form a self-resonant circuit.

[0028] The arithmetic unit 372 extracts resistance change components that correlate with the amount of lithium deposited, contained in at least one of the signal waveforms of the current and voltage flowing through the short circuit 371 when the terminals of the lithium-ion battery are short-circuited, and calculates an estimated value of the amount of lithium deposited from the extracted components.

[0029] The estimation method described above is very simple in its configuration and is extremely useful because it can detect specific battery degradation modes by adjusting the discharge frequency from the lithium-ion battery.

[0030] On the other hand, the internal resistance of lithium-ion batteries is in the range of a few mΩ to several hundred mΩ, and they are easily affected by disturbances such as temperature and parasitic impedance. Therefore, it was found that it is difficult to accurately determine the amount of lithium deposited using the estimation method described above. This was discovered after diligent research by the inventors.

[0031] Taking this into account, the calculator 372 of the deposition amount detection unit 37 calculates a corrected value as the lithium deposition amount by correcting the above estimated value with both the battery temperature detected by the temperature sensor 31 and the parasitic resistance value pre-stored in the storage unit 51 of the monitoring module 50, as shown in Figure 6.

[0032] Parasitic resistance is a part of the parasitic impedance that occurs between the lithium-ion battery and the short circuit 371. Parasitic resistance changes depending on the battery temperature. Therefore, the arithmetic unit 372 corrects the parasitic resistance stored in the memory unit 51 according to the battery temperature and calculates the lithium deposition amount using the corrected parasitic resistance. In addition to functioning as a means for estimating the lithium deposition amount, the arithmetic unit 372 also functions as a calibration means for correcting the estimated lithium deposition amount.

[0033] Here, the parasitic resistance value is determined by connecting the deposition amount detection unit 37 to a calibration device CD having a known impedance Z, as shown in Figure 7, before connecting it to the lithium-ion battery. Specifically, as shown in Figure 8, the short circuit 371 is connected to the calibration device CD, and the parasitic resistance value is determined in this state. The parasitic resistance value is then stored in the storage unit 51 of the monitoring module 50. Next, the short circuit 371 is connected to the battery module BM, and the lithium deposition amount is calculated in this state.

[0034] The deposition amount detection unit 37 configured in this way ensures robustness against parasitic impedance and temperature changes. This is very effective in accurately detecting the amount of lithium deposited.

[0035] The short-circuit circuit 371 in this embodiment includes a coil, which makes it bulky, so it is necessary to miniaturize it appropriately with mounting in mind. Miniaturization can be achieved, for example, by improving the saturation magnetic flux density of the coil. Specific means of miniaturization include, for example, using a coil made of a material with high magnetic flux density, or improving the saturation magnetic flux density by providing a gap.

[0036] The coating detection unit 38 detects the thickness of the coating formed at the interface between the negative electrode and the electrolyte during charging of the lithium-ion battery. This coating is also called the SEI layer. SEI is an abbreviation for Solid Electrolyte Interphase.

[0037] The thickness of the SEI layer correlates with the behavior of the current and voltage when the lithium-ion battery is short-circuited at both ends by the short-circuit circuit 371. The coating detection unit 38 estimates the thickness of the SEI layer from the behavior of the current and voltage when the lithium-ion battery is short-circuited at both ends by the short-circuit circuit 371. Specifically, when the battery is short-circuited at both ends by the short-circuit circuit 371, the coating detection unit 38 extracts a component that correlates with the thickness of the SEI layer from at least one of the signal waveforms of the current and voltage flowing through the short-circuit circuit 371, and estimates the thickness of the SEI layer from the extracted component. When detecting the thickness of the SEI layer, it is desirable to correct for the battery temperature, similar to the detection of lithium deposition amount.

[0038] Here, the amount of lithium deposited and the thickness of the SEI layer are physical quantities that correlate more strongly with battery capacity degradation than the battery voltage and current. In this embodiment, the deposit amount detection unit 37 and the film detection unit 38 constitute a "degradation detection unit" that detects physical quantities that correlate more strongly with battery capacity degradation than the battery voltage and current. Furthermore, the amount of lithium deposited is one of the factors that can lead to an abnormal heat generation phenomenon in which the battery temperature continues to rise unintentionally. For this reason, the deposit amount detection unit 37 constitutes a "factor monitoring unit" that monitors factors that can lead to an abnormal heat generation phenomenon.

[0039] As shown in Figure 4, a battery state detection unit 39 is mounted on the flexible printed circuit board (FPC) to detect the battery state. The battery state detection unit 39 detects battery states such as excessive temperature rise, overcharging, and significant changes in internal resistance, based on the sensor outputs of the temperature sensor 31, current sensor 32, and voltage sensor 33.

[0040] Next, the monitoring module 50 will be described. The monitoring module 50 is a satellite module that is directly attached to the battery module BM. The monitoring module 50 is located on the high-voltage side of the BMU. The monitoring module 50 is electrically connected to the battery and constitutes an "abnormality detection unit" that detects abnormalities in the battery.

[0041] The monitoring module 50 includes a storage unit 51, a wireless communication unit 52, an internal resistance detection unit 53, a monitoring IC 54, and the like. The storage unit 51 stores various information such as a unique ID set for each monitoring module 50, the monitoring results of the battery module BM, and the aforementioned parasitic resistance values. The storage unit 51 is composed of a non-transitional physical storage medium.

[0042] The wireless communication unit 52 is a communication device that enables bidirectional communication with the battery ECU 100. The monitoring module 50 receives various signals from the battery ECU 100 and transmits the monitoring results of the monitoring module 50 to the battery ECU 100.

[0043] The internal resistance detection unit 53 is a device that detects the internal resistance of the battery based on various information output from the sensor unit 30. Furthermore, changes in the internal resistance of the battery are one of the factors that can lead to abnormal heat generation. For this reason, the internal resistance detection unit 53 constitutes a "factor monitoring unit" that monitors factors that can lead to abnormal heat generation.

[0044] The monitoring IC54 is electrically connected to the battery and detects abnormalities in the battery. Based on the monitoring results of factors that lead to abnormal overheating, the monitoring IC54 prevents the occurrence of abnormal overheating, and also detects abnormal conditions that occur in the battery in the initial stages of abnormal overheating, and implements countermeasures against abnormal overheating based on the detection results of the abnormal conditions.

[0045] The monitoring IC 54 includes an ASIC circuit with an algorithm that performs at least part of the monitoring of factors leading to abnormal heat generation and the detection of abnormal conditions occurring in the battery in the initial stages of abnormal heat generation. Specifically, the monitoring IC 54 has a configuration in which a diagnostic unit 541, a SOH estimation unit 542, and a monitoring control unit 543 are functional units that perform various controls.

[0046] Since the amount of lithium deposited is a parameter that greatly affects the remaining value of the battery, it is also important to verify the accuracy of this parameter. The diagnostic unit 541 compares a predetermined battery state estimated from the amount of lithium deposited with a battery state estimated from other factors besides the amount of lithium deposited, and diagnoses whether the deposit amount detection unit 37 is appropriate.

[0047] The diagnostic unit 541 estimates the battery's volume fraction SOH from the lithium deposition amount detected by the deposition amount detection unit 37, for example, as shown in Figure 9. The diagnostic unit 541 also estimates the battery's volume fraction SOH based on the sensor outputs of the temperature sensor 31, current sensor 32, and voltage sensor 33. SOH is an abbreviation for State of Health.

[0048] Next, the diagnostic unit 541 compares the volume ratio SOH estimated from the lithium deposition amount with the volume ratio SOH estimated from the battery temperature, current, and voltage using a state comparator to diagnose whether the deposition amount detection unit 37 is appropriate. For example, the diagnostic unit 541 diagnoses the deposition amount detection unit 37 as appropriate if the discrepancy between the volume ratio SOH estimated from the lithium deposition amount and the volume ratio SOH estimated from the battery temperature, current, and voltage is within a predetermined range. On the other hand, the diagnostic unit 541 diagnoses the deposition amount detection unit 37 as unsuitable if the discrepancy between the volume ratio SOH estimated from the lithium deposition amount and the volume ratio SOH estimated from the battery temperature, current, and voltage exceeds a predetermined range. If the deposition amount detection unit 37 is diagnosed as unsuitable, the monitoring IC 54 prohibits the detection of lithium deposition amount and control processing using the lithium deposition amount, or transmits a signal indicating a malfunction of the deposition amount detection unit 37 to the battery ECU 100 via the wireless communication unit 52. In this embodiment, the battery volume ratio (SOH) is used as an example of the battery state estimated by the diagnostic unit 541, but the diagnostic unit 541 may be configured to estimate battery states other than the volume ratio.

[0049] Japanese Patent Publication No. 2014-102076 discloses a method for calculating the fully charged state of a battery. In this calculation method, first, the change in charge / discharge amount between a first and second time point is calculated by integrating the current value of the battery's output current over time. Then, the OCV at the first and second time points is measured, and the remaining capacity (SOC) at the first and second time points is calculated using the SOC-OCV curve, and the change amount ΔSOC, which is calculated as the deviation of the remaining capacity (SOC) at each time point, is calculated. Next, the fully charged state of the battery is calculated by dividing the change in charge / discharge amount by the change in remaining capacity (SOC) ΔSOC. Furthermore, the volume ratio (SOH) of the battery is obtained by dividing the fully charged state of the battery by the initial value of the fully charged state.

[0050] However, the above methods for calculating remaining capacity (SOC) and volume ratio (SOH) lack real-time capabilities and practicality. This is because, in order to avoid the influence of errors in the current sensor 32 and voltage sensor 33, the battery charge and discharge amounts can only be calculated in scenarios where a certain amount of charge or discharge occurs. Furthermore, when calculating the charge and discharge amounts, the offset error of the current sensor 32 causes the calculation error of the volume ratio (SOH) to increase over time.

[0051] Taking these factors into consideration, the SOH estimation unit 542 estimates the battery's volumetric SOH based on physical quantities that are more correlated with battery capacity degradation than the battery's voltage and current. The SOH estimation unit 542 constitutes the "volumetric estimation unit".

[0052] One factor contributing to battery degradation is the increase in the battery's internal resistance. The battery's internal resistance is strongly correlated with physical quantities such as lithium deposition and the battery's internal resistance itself. Furthermore, the battery's internal resistance is temperature-dependent and affects the battery's current and voltage.

[0053] Taking these factors into consideration, the SOH estimation unit 542 of this embodiment estimates the volume fraction SOH using a volume fraction SOH estimation model, as shown in Figure 10, based on the lithium deposition amount, SEI layer thickness, battery temperature, current, and voltage. The volume fraction SOH estimation model is, for example, a control map or function that defines the relationships between the volume fraction SOH, lithium deposition amount, SEI layer thickness, battery temperature, current, and voltage. The estimation model may be, for example, a model obtained by deep learning, reinforcement learning, or deep reinforcement learning using a neural network.

[0054] This method enables real-time battery state diagnosis, which was difficult to achieve by estimating the volume fraction (SOH) based on charge / discharge amounts. Furthermore, by accurately measuring temperature, the temperature effect on the battery's internal resistance can be excluded, allowing for the proper extraction of degradation information, thus improving accuracy.

[0055] The monitoring and control unit 543 prevents the occurrence of abnormal heat generation based on the monitoring results of factors that lead to abnormal heat generation, and also detects abnormal conditions that occur in the battery in the initial stages of abnormal heat generation, and implements countermeasures against the abnormal heat generation based on the detection results of the abnormal conditions. Although not shown in the figure, the monitoring IC 54 controls circuits that equalize the voltage of multiple battery cells C, etc.

[0056] Next, I will explain the battery ECU100. The battery ECU100 is the main module in the BMU and controls the charging and discharging of each battery module BM. The battery ECU100 is located on the low-voltage side of the BMU.

[0057] Specifically, the battery ECU 100 is composed of a microcomputer equipped with a processor, memory, I / O, and a wireless communication device 110. The battery ECU 100 is configured to communicate with each monitoring module 50A, 50B, and 50C via the wireless communication device 110. The battery ECU 100 is also connected to various ECUs via a communication path such as CAN. Examples of various ECUs include a thermal management ECU that controls the battery's temperature control equipment and an ECU for an HMI device mounted on the vehicle. The battery ECU 100 can notify externally of various battery statuses via the HMI device, etc.

[0058] The battery pack 1 configured in this way includes a rechargeable battery such as a lithium-ion battery. In this type of battery, a specific component inside the battery may overheat due to some trigger, and this heat may further cause other components to overheat, resulting in an abnormal overheating phenomenon where the battery temperature continues to rise unintentionally. Such an abnormal overheating phenomenon is undesirable because it significantly reduces the thermal reliability of the battery. Therefore, in lithium-ion batteries and the like, it is important to detect the presence or absence of an abnormal overheating phenomenon in the battery to ensure thermal reliability.

[0059] Here, we will explain the changes in the output of various sensors before and after the abnormal heat generation phenomenon, referring to Figure 11. Figure 11 shows an example of the results of the inventors' verification of the changes in the output of various sensors before and after the abnormal heat generation phenomenon.

[0060] As shown in Figure 11, in the stage before the abnormal heat generation phenomenon occurs, the first sign of a battery abnormality is that the volume of the battery begins to change due to an increase in the gas pressure inside the battery cell. As a result, the output of the strain sensor 34 shows an increasing trend.

[0061] Subsequently, as the volume change of the battery increases, the battery is damaged and gas leakage from inside the battery cell begins. This causes the output of the gas sensor 35 to tend to increase. When the battery is damaged, the gas pressure inside the battery decreases, and the output of the strain sensor 34 tends to decrease.

[0062] Furthermore, although not shown in Figure 11, as battery degradation progresses, lithium deposition occurs inside the battery and the thickness of the SEI layer increases, leading to an increase in the battery's internal resistance.

[0063] When an abnormal overheating phenomenon occurs, the battery temperature and the pressure inside the battery pack 1 (i.e., the internal pack pressure) rise sharply, and the battery voltage drops rapidly. Furthermore, the output of the gas sensor 35 shows an increasing trend. These signs are particularly noticeable in the initial stages of the abnormal overheating phenomenon.

[0064] Taking these factors into consideration, the battery monitoring device 20 executes control processing to prevent and detect abnormal heat generation phenomena early. An example of the control processing performed by the battery monitoring device 20 will be explained below with reference to Figure 12.

[0065] The control process shown in Figure 12 is performed by the battery monitoring device 20 periodically or irregularly, for example, during vehicle startup and for a predetermined period after stopping. Each process shown in this flowchart is implemented by the respective functional units of the battery monitoring device 20. Furthermore, each step in implementing this process can also be understood as each step in implementing the battery monitoring method.

[0066] As shown in Figure 12, in step S100, the battery monitoring device 20 reads various signals from the sensor unit 30 and the like. Then, in step S105, the battery monitoring device 20 determines whether or not an abnormal heat generation phenomenon has occurred. As mentioned above, in the initial stages of an abnormal heat generation phenomenon, the battery temperature, pack pressure, and the output of the gas sensor 35 rise sharply, while the battery voltage drops sharply. Taking this into consideration, the battery monitoring device 20 determines whether or not an abnormal heat generation phenomenon has occurred based on the output of at least some of the sensors, including the temperature sensor 31, the voltage sensor 33, the gas sensor 35, and the pack pressure sensor 36.

[0067] When an abnormal overheating phenomenon is detected, the battery monitoring device 20 proceeds to step S110 to implement countermeasures against the abnormal overheating phenomenon. These countermeasures include an external notification process to inform the outside of the abnormal overheating phenomenon, and a battery protection process that includes at least one of the following: cooling of the battery and charge / discharge control.

[0068] In the external notification process, for example, a signal indicating the occurrence of an abnormal overheating phenomenon is output to the battery ECU 100, and via the battery ECU 100, devices with notification functions such as HMI devices are activated to inform the user and battery manager of the occurrence of the abnormal overheating phenomenon.

[0069] In the battery protection process, for example, a signal is output to the battery ECU 100 instructing it to cool the battery, and the battery temperature control device is operated via the battery ECU 100 to cool the battery. This type of battery cooling can delay the progression of abnormal heat generation in the battery. In addition, the battery protection process also outputs a signal to the battery ECU 100 instructing it to limit the charging and discharging of the battery, thereby suppressing the self-heating of the battery by restricting its operation. This type of charge and discharge control can also delay the progression of abnormal heat generation in the battery. The battery protection process constitutes an extension process that extends the battery's lifespan.

[0070] Furthermore, as one measure to address the abnormal heat generation phenomenon, the battery monitoring device 20 identifies abnormal cells among the multiple battery cells C as abnormal cells based on at least one of the monitoring results for each of the multiple battery cells C and the detection results for abnormal battery conditions. This allows for restricting the use of abnormal cells and delaying the progression of the abnormal heat generation phenomenon.

[0071] Furthermore, countermeasures against abnormal overheating are not limited to the above-mentioned processes and may be implemented through other processes. For example, countermeasures against abnormal overheating may include illuminating a warning light or sounding an alarm.

[0072] On the other hand, if no abnormal heat generation phenomenon is detected, the battery monitoring device 20 proceeds to the processing from step S115 onward. The processing from step S115 onward is a process to prevent the occurrence of abnormal heat generation.

[0073] In step S115, the battery monitoring device 20 determines whether or not battery overcharging has been detected. Battery overcharging can be detected, for example, by monitoring the sensor output of the voltage sensor 33. If battery overcharging is detected, the battery monitoring device 20 performs a charge suppression process in step S120 and returns to step S115. This charge suppression process suppresses battery charging or discharges the battery.

[0074] If no battery overcharging is detected, the battery monitoring device 20 determines in step S125 whether or not battery overheating has been detected. Battery overheating can be detected, for example, by monitoring the sensor output of the temperature sensor 31. If battery overheating is detected, the battery monitoring device 20 performs output limiting or cooling control in step S130 and returns to step S115. Output limiting suppresses, for example, the charging and discharging of the battery. Cooling control cools the battery using, for example, a battery temperature control device.

[0075] If no overheating of the battery is detected, the battery monitoring device 20 determines in step S135 whether or not new lithium deposition has been detected. Lithium deposition can be detected, for example, by monitoring the increase in the amount of lithium deposition detected by the deposition amount detection unit 37.

[0076] If new lithium deposition is detected, the battery monitoring device 20 performs charging, regeneration control, and heating control in step S140 and returns to step S115. In charging and regeneration control, for example, battery charging is suppressed. In heating control, for example, the battery is heated by a battery temperature control device. Each of the processes performed when lithium deposition is detected constitutes an extension process that extends the battery's lifespan.

[0077] If no new lithium deposition is detected, the battery monitoring device 20 determines in step S145 whether or not a change in the battery's internal resistance has been detected. The battery's internal resistance can be detected, for example, by monitoring the increase in internal resistance detected by the internal resistance detection unit 53.

[0078] If a change in the battery's internal resistance is detected, the battery monitoring device 20 performs battery output limiting, temperature control, and degradation level notification in step S150, and then returns to step S115. Output control, for example, suppresses battery discharge. Temperature control, for example, adjusts the battery temperature using a temperature control device so that the battery temperature is maintained within an appropriate range. In the degradation level notification, the degree of battery degradation is determined from the battery's internal resistance, and the degradation level determination result or the estimated battery replacement time based on the determination result is notified externally. Each process performed when a change in internal resistance is detected constitutes an extension process that extends the battery's lifespan.

[0079] If no change in the internal resistance of the battery is detected, the battery monitoring device 20 determines in step S155 whether or not deformation of the battery has been detected. Battery deformation can be detected by monitoring the sensor output of the strain sensor 34.

[0080] If battery deformation is detected, the battery monitoring device 20 implements a battery output limit in step S160 and returns to step S115. Output control, for example, suppresses the charging and discharging of the battery.

[0081] If no battery deformation is detected, it is considered that there are no signs of abnormal overheating and the device is in a normal state. Therefore, if no battery deformation is detected, the battery monitoring device 20 terminates the control process shown in Figure 12.

[0082] Incidentally, with the rapid electrification of vehicles, a large amount of used batteries are expected to be generated in the near future. Since battery manufacturing involves the emission of large amounts of CO2 and the use of rare metals, it is hoped that a battery ecosystem adapted to a circular economy will be built by selecting reuse, rebuilding, or recycling options for used batteries depending on the remaining capacity (SOC) and volume ratio (SOH). In order to build such a battery ecosystem, it is important to correctly diagnose the value of batteries, such as remaining capacity (SOC) and volume ratio (SOH). Furthermore, it is conceivable that batteries will be stored after their use in vehicles ends until a secondary use is decided, but batteries continue to discharge even when not in use, and deterioration may progress depending on the storage conditions. Therefore, secondary users need to know the remaining capacity (SOC) and volume ratio (SOH) of the battery at that moment, making real-time battery diagnosis important.

[0083] As described above, the battery monitoring device 20 of this embodiment can determine the remaining capacity (SOC) and volume ratio (SOH) in real time. Considering this, it is desirable to designate the battery module BM and the battery monitoring device 20 as a battery unit UT and distribute the market in units of this battery unit UT. Furthermore, it is desirable to manage the battery module BM using a battery management system BMS, for example, as shown in Figure 13.

[0084] The battery management system (BMS) comprises a battery monitoring device 20 and a battery management device 60 attached to the battery module BM. The battery management device 60 includes a performance determination unit 61, a value setting unit 62, and a performance notification unit 63.

[0085] The performance determination unit 61 determines whether the battery can be reused based on the volume ratio SOH estimated by the SOH estimation unit 542 of the battery monitoring device 20. For example, the performance determination unit 61 determines that the battery can be reused if the volume ratio SOH estimated by the SOH estimation unit 542 is equal to or greater than a predetermined value, and that it cannot be reused if it is less than the predetermined value. The performance determination unit 61 may also determine whether the battery can be reused based on battery conditions other than the volume ratio SOH.

[0086] The value setting unit 62 determines whether there is a battery abnormality based on the volume ratio SOH estimated by the SOH estimation unit 542 of the battery monitoring device 20, and sets the remaining value of the battery if there is an abnormality. For example, the value setting unit 62 estimates the remaining value of the battery lower as the volume ratio SOH decreases. The value setting unit 62 may also set the remaining value of the battery based on battery conditions other than the volume ratio SOH.

[0087] The performance notification unit 63 determines whether the volume ratio SOH estimated by the SOH estimation unit 542 of the battery monitoring device 20 is within the allowable range of the volume ratio SOH indicated in the battery specification data, and outputs the result of this determination to the outside.

[0088] The performance notification unit 63 acquires battery specification data provided by the battery manufacturer, etc., and stores it in memory. The performance notification unit 63 then notifies the battery distributor, secondary users, etc., of this fact if, for example, the volume ratio SOH estimated by the SOH estimation unit 542 is within the acceptable range indicated in the specification data. The performance notification unit 63 also notifies the battery distributor, secondary users, etc., of this fact if, for example, the volume ratio SOH estimated by the SOH estimation unit 542 is outside the acceptable range indicated in the specification data, that secondary use of the battery is difficult.

[0089] According to the battery monitoring device 20 and battery monitoring method described above, effective measures against abnormal heat generation, effective detection of lithium deposition amount, and effective estimation of volume fraction SOH can be implemented. Specifically, these are as follows:

[0090] [Measures against abnormal fever] The battery monitoring device 20 and battery monitoring method monitor factors that lead to abnormal heat generation and prevent the occurrence of abnormal heat generation based on the monitoring results of those factors. In addition, the battery monitoring device 20 and battery monitoring method detect abnormal conditions that occur in the battery at the initial stage of abnormal heat generation and implement countermeasures against the abnormal heat generation based on the detection results of the abnormal conditions. This makes it possible to prevent the occurrence of abnormal heat generation in the first place, and even if abnormal heat generation does occur, effective thermal countermeasures can be implemented by taking countermeasures from the initial stage of occurrence.

[0091] In addition, the battery monitoring device 20 provides the following benefits:

[0092] (1) The monitoring module 50 of the battery monitoring device 20 performs monitoring of factors that lead to abnormal heat generation and detection of abnormal battery conditions in parallel. In other words, the monitoring module 50 detects abnormal battery conditions regardless of the monitoring results of factors that lead to abnormal heat generation. As a result, for example, compared to detecting abnormal conditions after monitoring factors that lead to abnormal heat generation, abnormal conditions can be detected earlier, and countermeasures against abnormal heat generation can be implemented earlier.

[0093] (2) Measures to be taken when an abnormal overheating phenomenon occurs include external notification processing to inform the outside of the occurrence of the abnormal overheating phenomenon, or battery protection processing by controlling the battery temperature and charging / discharging. If external notification processing is included in the measures to be taken when an abnormal overheating phenomenon occurs, it becomes easier to implement measures by external devices of the battery monitoring device 20 or measures in cooperation with external devices, in addition to the measures that the battery monitoring device 20 itself can take. Also, if battery protection processing is included in the measures to be taken when an abnormal overheating phenomenon occurs, it becomes possible to properly protect the battery.

[0094] (3) The monitoring module 50 performs an extension process to extend the battery life in accordance with the monitoring results of the factors causing the abnormal heat generation phenomenon. By configuring the system to perform a battery life extension process in accordance with the monitoring results of the factors leading to the abnormal heat generation phenomenon, it becomes possible to appropriately extend the battery life.

[0095] (4) Factors that lead to abnormal heat generation include at least one of lithium deposition inside the battery and the battery's internal resistance. Lithium deposition and increased internal resistance inside lithium-ion batteries are factors that cause abnormal heat generation in batteries. Therefore, monitoring lithium deposition and internal resistance makes it easier to prevent the occurrence of abnormal heat generation in batteries.

[0096] (5) The monitoring module 50 identifies any abnormal battery cell C as an abnormal cell based on at least one of the monitoring results for each of the multiple battery cells C and the detection results for abnormal conditions in the multiple battery cells C. In this way, if an abnormal cell can be identified from among the multiple battery cells C, it becomes possible, for example, to restrict the use of the abnormal cell to prevent the occurrence of abnormal heat generation or to delay the progression of abnormal heat generation.

[0097] (6) The monitoring module 50 is configured to detect at least one of the following abnormal conditions of the battery: abnormal internal pressure in the sealed container 11, abnormal battery temperature, abnormal battery voltage, and abnormal gas in the sealed container 11. In the initial stages of an abnormal heat generation phenomenon, the internal pressure of the sealed container 11 containing the battery, the battery temperature, the battery voltage, and the gas state inside the sealed container 11 become abnormal. Therefore, if the monitoring module 50 is configured to detect at least one of the following: abnormal internal pressure in the sealed container 11, abnormal battery temperature, abnormal battery voltage, and abnormal gas in the sealed container 11, it becomes easier to detect the abnormal heat generation phenomenon in its initial stages.

[0098] (7) The battery monitoring device 20 includes an ASIC circuit having an algorithm that performs at least part of the monitoring of factors leading to abnormal heat generation and the detection of abnormal battery conditions. This makes it possible to monitor factors leading to abnormal heat generation and detect abnormal conditions with a simple configuration.

[0099] (8) The monitoring module 50 is configured to determine the degree of battery degradation based on the monitoring results of factors that lead to abnormal heat generation, and to notify an external party of the determination result of the degree of degradation or the estimated battery replacement time based on the determination result. By configuring the device to determine the degree of battery degradation from the monitoring results of factors that lead to abnormal heat generation, a dedicated device for determining the degree of battery degradation becomes unnecessary. This contributes to the simplification of the battery monitoring device 20.

[0100] (9) The connecting member 21 that connects the battery and the monitoring module 50 includes a flexible printed circuit board (FPC) on which a part of the sensor unit 30 is mounted. By mounting a part of the sensor unit 30 on the flexible printed circuit board (FPC) that constitutes the connecting member 21 in this way, it is possible to monitor factors that could lead to abnormal heat generation of the battery at a location close to the battery.

[0101] [Detection of lithium deposition amount] The deposition amount detection unit 37 of the battery monitoring device 20 calculates an estimated lithium deposition amount based on the change in at least one of the current and voltage when the ends of the lithium-ion battery are short-circuited by the short-circuit circuit 371. The deposition amount detection unit 37 then corrects the estimated lithium deposition amount with the battery temperature. This reduces the influence of the battery temperature included in the estimated lithium deposition amount, improving the detection accuracy of the lithium deposition amount and thus ensuring the reliability of the deposition amount detection unit 37.

[0102] Furthermore, the deposition amount detection unit 37 corrects the estimated lithium deposition amount using the parasitic resistance value stored in the memory unit 51. This reduces the influence of parasitic impedance included in the estimated lithium deposition amount, thereby improving the detection accuracy of the lithium deposition amount and ensuring the reliability of the deposition amount detection unit 37.

[0103] (1) Specifically, the deposition amount detection unit 37 corrects the parasitic resistance value stored in the memory unit 51 according to the battery temperature, and calculates the lithium deposition amount using the corrected parasitic resistance value. This reduces the influence of battery temperature and parasitic impedance included in the estimated lithium deposition amount, thereby improving the detection accuracy of the lithium deposition amount.

[0104] (2) The parasitic resistance value is determined by connecting the short circuit 371 to a calibration device CD having a known impedance Z before connecting it to the lithium-ion battery. This allows for accurate determination of the parasitic resistance value of the deposition amount detection unit 37. This greatly contributes to improving the accuracy of lithium deposition amount detection.

[0105] (3) The battery monitoring device 20 includes a diagnostic unit 541 that compares a predetermined battery state estimated from the lithium deposition amount with a predetermined battery state estimated from other factors besides the lithium deposition amount to diagnose the suitability of the deposition amount detection unit 37. As a result, the reliability of the deposition amount detection unit 37 can be ensured because the diagnostic unit 541 can diagnose the reliability of the deposition amount detection unit 37.

[0106] [Modified version of battery monitoring device 20] The battery monitoring device 20 is not identical to the one described above, and may differ in some respects from it. Furthermore, the technical details described above can be adapted to devices and systems other than in-vehicle equipment.

[0107] [Estimation of floor area ratio (SOH)] The battery monitoring device 20 detects a physical quantity that is more correlated with battery capacity degradation than the battery voltage and current, and estimates the battery's state of health (SOH) based on that physical quantity. By estimating the SOH using a physical quantity highly correlated with battery capacity degradation in this way, the need to avoid errors is reduced compared to determining the SOH from the battery's current and voltage, allowing for quick estimation of the SOH. Therefore, the battery monitoring device 20 of this invention makes it possible to understand the battery state in a practical manner.

[0108] (1) Here, the amount of lithium deposited and the thickness of the SEI layer are physical quantities that directly affect the degradation of the battery's capacity. Therefore, real-time performance can be ensured by detecting the amount of lithium deposited and the thickness of the SEI layer, and then determining the volume fraction SOH based on these values. Furthermore, the degree of cracking of the positive electrode active material inside the battery is a physical quantity that directly affects the degradation of the battery's capacity. Therefore, the detection accuracy of the volume fraction SOH can be improved by configuring the system to determine the volume fraction SOH not only based on the amount of lithium deposited and the thickness of the SEI layer, but also based on the degree of cracking of the positive electrode active material. The degree of cracking of the positive electrode active material can be estimated based on the behavior of the current and voltage when the ends of the lithium-ion battery are short-circuited, or based on the sensor output of the strain sensor 34 or the ultrasonic sensor.

[0109] (2) The amount of lithium deposited and the thickness of the SEI layer in a lithium-ion battery are correlated with the behavior of the current and voltage when the ends of the lithium-ion battery are short-circuited. Taking this into account, the battery monitoring device 20 calculates at least one of the amount of lithium deposited and the thickness of the SEI layer based on the change in at least one of the current and voltage when the ends of the lithium-ion battery are short-circuited using the short-circuit circuit 371.

[0110] (3) Specifically, the battery monitoring device 20 corrects at least one of the lithium deposition amount and the SEI layer thickness with the battery temperature. This reduces the influence of the battery temperature on the estimated lithium deposition amount and the SEI layer thickness, thereby improving the detection accuracy of the lithium deposition amount and the SEI layer thickness.

[0111] (4) The battery management system (BMS) determines whether or not a battery can be reused based on the volume ratio SOH estimated by the SOH estimation unit 542 of the battery monitoring device 20. This makes it easier to decide whether to reuse, rebuild, or recycle when reusing a battery. This greatly contributes to the construction of a battery ecosystem adapted to a circular economy.

[0112] (5) The battery management system (BMS) determines whether there is a battery abnormality based on the volume ratio SOH estimated by the SOH estimation unit 542 of the battery monitoring device 20, and sets the remaining value of the battery if there is an abnormality. This also makes it easier to decide whether to reuse, rebuild, or recycle when reusing a battery, thus contributing to the construction of a battery ecosystem adapted to a circular economy.

[0113] (6) The battery management system (BMS) determines whether the volume ratio SOH estimated by the SOH estimation unit 542 of the battery monitoring device 20 is within the allowable range of the volume ratio SOH indicated in the battery specification data, and outputs the result of this determination to the outside. This also makes it easier to decide whether to reuse, rebuild, or recycle when reusing batteries, and thus greatly contributes to the construction of a battery ecosystem adapted to a circular economy.

[0114] [A modified example of a battery management system (BMS)] The battery management system (BMS) is not identical to the one described above, and may differ in some respects. Furthermore, the technical details described above can be applied to equipment and systems other than in-vehicle devices.

[0115] The above concludes the explanation regarding the BMU and related components. The following describes the charging system BCS and the battery evaluation system BRS.

[0116] [Charging System BCS] The BCS charging system will be described below with reference to Figures 14 to 19. The BCS charging system is a system for charging the battery module BM included in the battery pack 1. The BCS charging system is applied, for example, to a vehicle charging station.

[0117] As shown in Figure 14, the charging system BCS comprises a battery monitoring device 20, a battery ECU 100, a charger 120, and a charging cable CC. In this embodiment, the battery monitoring device 20 and the battery ECU 100 included in the battery pack 1 constitute battery-side equipment that monitors the battery status, including the amount of lithium deposited in the lithium-ion battery.

[0118] The battery module BM is connected to the vehicle's power control unit PCU and motor generator MG via a switch SW2, such as the system main relay. For example, when the vehicle's start switch is turned on, switch SW2 is turned on, and the battery module BM is electrically connected to the motor generator MG via the power control unit PCU, becoming ready for charging and discharging.

[0119] The battery monitoring device 20 and the battery ECU 100 are basically configured in the same way as described above. The battery ECU 100 can communicate with the charger 120 via the communication device CE. When the battery ECU 100 is able to communicate with the charger 120, it notifies the charger 120 of battery information, including the amount of lithium deposited and the remaining capacity (SOC). The battery ECU 100 also determines whether or not the battery is in a rechargeable state and notifies the charger 120 of this determination as one of the battery information items. Furthermore, the battery ECU 100 sets the CC charging current, which is the target current amount during constant current charging, and the CV charging voltage, which is the target voltage during constant voltage charging, and notifies the charger 120 of these set values. Communication between the communication device CE and the charger 120 is performed via the CAN and the communication lines included in the charging cable CC.

[0120] The charging cable CC electrically connects the battery module BM and the charger 120. The charging cable CC consists of a cable, a charging connector (not shown), a control box (not shown), and the like.

[0121] The charger 120 is a device for charging the battery module BM. The charger 120 is composed of equipment conforming to charging standards such as CHAdeMO, CCS, and GB / T. A switch SW1 is provided between the charger 120 and the battery module BM to turn the electrical connection between the charger 120 and the battery module BM on and off. This switch SW1 may be provided on the charger 120 side or on the vehicle side.

[0122] The charger 120 includes an information acquisition unit 121, a charging determination unit 122, a charging control unit 123, and a charging time calculation unit 124. The information acquisition unit 121, the charging determination unit 122, the charging control unit 123, and the charging time calculation unit 124 are, for example, composed of a microcomputer equipped with a processor, memory, I / O, etc.

[0123] The information acquisition unit 121 acquires battery information, including the amount of lithium deposited and the remaining capacity (SOC), from the battery monitoring device 20 and the battery ECU 100 when the battery module BM is being charged. The information acquisition unit 121 also acquires the CC charging current and CV charging voltage from the battery ECU 100.

[0124] Here, the amount of lithium deposited is important information indicating the safety of the battery module BM. For this reason, the information acquisition unit 121 of this embodiment is configured to notify the outside of the battery information, including the amount of lithium deposited, via the notification device ND. The notification device ND is composed of equipment such as a display, speaker, and lamp.

[0125] The charging determination unit 122 determines whether or not the battery module BM can be charged based on the battery information acquired by the information acquisition unit 121. For example, the charging determination unit 122 determines whether or not the battery module BM can be charged based on the result of the determination performed by the battery ECU 100 as to whether or not it is in a rechargeable state. The charging determination unit 122 may also determine whether or not to charge based on the amount of lithium deposition acquired by the information acquisition unit 121.

[0126] The charging control unit 123 charges the battery module BM based on the determination result of the charging determination unit 122. If the determination result of the charging determination unit 122 indicates that the battery module BM can be charged, the charging control unit 123 charges the battery module BM; if the determination result indicates that the battery module BM cannot be charged, the charging control unit 123 does not charge the battery module BM.

[0127] The charge control unit 123 in this embodiment is configured to charge the battery module BM using a CCCV charging method, which involves charging with a constant current followed by charging with a constant voltage. In the following explanation, charging with a constant current may be referred to as CC charging, and charging with a constant voltage may be referred to as CV charging.

[0128] The charging time calculation unit 124 estimates the necessary charging time based on the battery status acquired by the information acquisition unit 121, and notifies the external party of the estimated necessary charging time via the notification device ND. The charging time calculation unit 124 can be configured to estimate the necessary charging time using, for example, a control map that defines the relationship between the remaining amount of the battery module BM and the necessary charging time. When the charger 120 notifies the external party of the necessary charging time via the notification device ND, it is desirable that the notification also includes how much shorter the charging time is compared to normal charging. Furthermore, it is desirable that the charger 120 notifies the user's information terminal of the remaining time until charging is complete.

[0129] The BCS charging system, configured as described above, is required to have higher energy density and faster charging capabilities. Recently, attempts have been made to shorten the charging time of the battery module BM by supporting 50kW for CHAdeMO 1.0, 400kW for CHAdeMO 2.0, and 900kW for CHAdeMO 3.0 on the charger 120 side.

[0130] While reducing charging time is possible by increasing the charging output, the increased charging current resulting from high-output charging can accelerate lithium deposition on the battery's negative electrode, potentially significantly impairing the battery's lifespan and safety.

[0131] To avoid this, as shown in Figure 15, a charging profile can be considered that prevents degradation and unsafe conditions by performing a pre-charge with a small current before CC charging, thereby detecting abnormalities such as deep discharge of the battery.

[0132] However, if pre-charging is performed for safety reasons, the charging time will be longer, which may be inconvenient for users. Furthermore, users may feel anxious or frustrated if the charging time is longer than they expected.

[0133] Taking these factors into consideration, the charging system BCS of this embodiment is configured such that the charger 120 determines whether or not to charge the battery module BM based on battery information acquired from the battery monitoring device 20 and the battery ECU 100.

[0134] The control process on the battery ECU 100 side when charging of the battery module BM is initiated will be explained below with reference to Figure 16. This control process is performed periodically or irregularly by the battery ECU 100. Each control step of the control process shown in Figure 16 constitutes a function implementation unit that realizes various functions performed by the battery ECU 100.

[0135] As shown in Figure 16, the battery ECU 100 determines in step S200 whether or not the charger 120 has been connected. The battery ECU 100 waits until the charger 120 is connected, and then proceeds to step S210.

[0136] In step S210, the battery ECU 100 performs initial processing. During this initial processing, the battery ECU 100 initializes flags and other parameters, and obtains monitoring results from the battery monitoring device 20.

[0137] Next, the battery ECU 100 determines whether the battery module BM is in a rechargeable state. For example, the battery ECU 100 determines that it is rechargeable if the lithium deposition amount is within a predetermined value, and determines that it is not rechargeable if the lithium deposition amount exceeds the predetermined value. The battery ECU 100 may also determine that it is not rechargeable in the case of overcharge or deep discharge.

[0138] If charging of the battery module BM is possible, the battery ECU 100 sets the amount to charge the battery module BM in step S230. The battery ECU 100 determines the amount to charge the battery module BM based on, for example, the remaining capacity SOC, volume ratio SOH, etc. The battery ECU 100 also sets the CV charging voltage in step S240. The battery ECU 100 sets the CV charging voltage to, for example, a voltage value recommended as the charging voltage for the battery module BM. Furthermore, the battery ECU 100 sets the CC charging current in step S250. The battery ECU 100 sets the CC charging current to, for example, a current value recommended as the charging current for the battery module BM. The battery ECU 100 then notifies the charger 120 of the battery information indicating the battery state, including the amount of lithium deposited, and various settings including the CV charging voltage and CC charging current, and exits this control process.

[0139] On the other hand, if charging the battery module BM is not possible, the battery ECU 100 notifies the charger 120 in step S270 that charging the battery module BM is not possible, and exits this control process.

[0140] Next, the control processing on the charger 120 side during charging of the battery module BM will be explained with reference to Figure 17. This control processing is performed periodically or irregularly by the charger 120. Each control step of the control processing shown in Figure 17 constitutes a function implementation unit that realizes various functions performed by the charger 120.

[0141] As shown in Figure 17, in step S300, the charger 120 determines whether or not it has received a notification from the battery ECU 100. The charger 120 waits until it receives a notification from the battery ECU 100, and when it receives a notification from the battery ECU 100, it proceeds to step S310. In step S310, the charger 120 determines whether or not to charge the battery module BM based on the notification from the battery ECU 100. The processing in step S310 is performed by the charge determination unit 122 of the charger 120.

[0142] If the notification from the battery ECU 100 indicates that charging is not possible, the charger 120, in step S320, notifies the outside via the notification device ND that charging of the battery module BM is not possible and that the amount of lithium deposited is not possible, and does not perform charging of the battery module BM.

[0143] On the other hand, if the notification from the battery ECU 100 indicates that charging is possible, the charger 120 starts CC charging in step S330. The charger 120 charges the battery module BM using the CC charging current set by the battery ECU 100 as the target current.

[0144] Next, in step S340, the charger 120 determines whether the voltage of the battery module BM has reached a predetermined voltage. This determination process determines whether it is time to switch from CC charging to CV charging. The predetermined voltage is set to, for example, the CV charging voltage.

[0145] If the voltage of the battery module BM has not reached a predetermined voltage, the charger 120 determines in step S350 whether or not it has received a notification from the battery ECU 100 to update the CC charging current setting.

[0146] Here, during CC charging, the battery ECU 100 periodically or irregularly performs the setting update process shown in Figure 18. Specifically, as shown in Figure 18, in step S500, the battery ECU 100 determines whether the amount of lithium deposited is greater than a predetermined threshold. This threshold is set to a value that assumes the amount of lithium deposited when the battery is abnormal. If the amount of lithium deposited is less than or equal to the predetermined threshold, the battery ECU 100 skips the subsequent steps and exits the setting update process; if the amount of lithium deposited is greater than the predetermined threshold, it proceeds to step S510. In step S510, the battery ECU 100 resets the CC charging current to be smaller than the current value. For example, the battery ECU 100 resets the CC charging current to the current value before the amount of lithium deposited exceeded the predetermined threshold. Then, in step S520, the battery ECU 100 notifies the charger 120 of the CC charging current setting update.

[0147] Returning to Figure 17, when the charger 120 receives notification from the battery ECU 100 to update the CC charging current setting, in step S360, it updates the CC charging current to the current amount notified by the battery ECU 100. That is, if the amount of lithium deposition increases beyond a predetermined threshold during CC charging, the charger 120 reduces the amount of constant current. Note that the process in step S360 is performed by the charge control unit 123 of the charger 120.

[0148] Furthermore, when the voltage of the battery module BM reaches a predetermined voltage, the charger 120 proceeds to step S370 and starts CV charging. The charger 120 charges the battery module BM using the CV charging voltage set by the battery ECU 100 as the target voltage.

[0149] Next, in step S330, the charger 120 determines whether the current flowing through the battery module BM is less than or equal to a predetermined value, or whether the elapsed time since the start of charging the battery module BM is greater than or equal to a predetermined time.

[0150] If the current flowing through the battery module BM is greater than a predetermined value and the elapsed time since the start of charging is within a predetermined time, the charger 120 continues CV charging. If the current flowing through the battery module BM is less than or equal to a predetermined value, or if the elapsed time since the start of charging exceeds a predetermined time, the charger 120 performs a charging termination process in step S390 and then exits this control process. In the charging termination process, for example, the user is notified by the notification device ND of the completion of charging, the amount of charge, the battery status, etc.

[0151] The charging system BCS described above includes a charger 120 for a battery module BM containing a lithium-ion battery. The charger 120 includes an information acquisition unit 121 that acquires battery information from the battery-side device, a charging determination unit 122 that determines whether or not to charge the battery module BM based on the battery information, and a charging control unit 123 that charges the battery module BM based on the determination result of the charging determination unit 122. In this way, if the charger 120 is configured to determine whether or not to charge the battery module BM based on the battery information acquired from the battery-side device, the charging time can be shortened compared to a system that determines whether or not to charge the battery module BM by performing a pre-charge.

[0152] Furthermore, the BCS charging system of this embodiment has the following features. (1) The charge control unit 123 of the charger 120 is configured to charge the battery module BM by a CCCV charging method, which involves charging with a constant current followed by charging with a constant voltage. The charge control unit 123 reduces the amount of constant current if the amount of lithium deposition increases beyond a predetermined threshold during CC charging, for example, as shown in Figure 19. This suppresses the amount of lithium deposition during CC charging, thereby ensuring the safety of the battery module BM while preventing the charging time of the battery module BM from becoming too long.

[0153] (2) When charging by the charger 120 begins, the battery-side device periodically determines whether the amount of lithium deposition has increased beyond a threshold. If the amount of lithium deposition exceeds the threshold, the battery-side device sets the target current amount for constant-current charging to a value smaller than the current amount and notifies the charger 120 of the target current amount. When the charging control unit 123 obtains the target current amount from the battery-side device during CC charging, it adjusts the constant-current amount based on the target current amount. In this way, if the battery-side device periodically monitors the amount of lithium deposition and the charger 120 adjusts the current amount suitable for constant-current charging based on the monitoring results, it becomes possible to control the charging rate to maximize the charge rate so that lithium deposition does not occur. This makes it possible to appropriately reduce the waiting time for the user due to charging time.

[0154] (3) The charger 120 estimates the necessary charging time based on the battery status and notifies the external device ND of the estimated necessary charging time. This allows the user to have a rough idea of ​​the waiting time, thereby reducing the psychological burden on the user when charging the battery module BM.

[0155] (4) The charger 120 notifies the outside of the lithium deposition amount via the notification device ND. In this way, if information indicating the lithium deposition amount, as well as information indicating the required charging time, can be provided to the user, the user will be able to understand the safety of the lithium-ion battery, and it will be possible to alleviate the user's concerns about lithium-ion batteries.

[0156] [Modified versions of the BCS charging system] The BCS charging system is not identical to the one described above, and may differ in some respects. Furthermore, the technical details described above can be adapted to devices and systems other than in-vehicle equipment.

[0157] [Battery Evaluation System BRS and Battery Evaluation Method] Lithium-ion batteries may experience lithium deposition due to charging at low temperatures or high-speed charging. If lithium deposition progresses, an internal short circuit may occur, potentially leading to ignition and smoke. Therefore, when reusing rechargeable batteries, including lithium-ion batteries, it is desirable to assess safety not only based on the degree of degradation but also on the extent of lithium deposition.

[0158] Taking this into consideration, the battery evaluation system BRS and battery evaluation method of this embodiment determine the safety of a storage battery based on the amount of lithium deposited. Furthermore, the battery evaluation system BRS functions as a support system that assists in the reuse and rebuilding of battery modules BM. The battery evaluation system BRS and battery evaluation method will be described below with reference to Figures 20 to 22.

[0159] As shown in Figure 20, the battery evaluation system BRS includes a battery monitoring device 20, which serves as a battery monitoring unit for monitoring the battery state of the battery module BM, and an evaluation device 130 for evaluating the battery module BM.

[0160] The battery monitoring device 20 is basically configured in the same way as described above. The battery monitoring device 20 is configured to calculate the amount of lithium deposited in the lithium-ion battery contained in the battery module BM as one indicator of the battery state. The battery monitoring device 20 can output battery state information, including the monitoring results of the battery state including the amount of lithium deposited, to the outside using the wireless communication unit 52 of the monitoring module 50. In addition to the amount of lithium deposited, this battery state information also includes battery type information indicating the application of the battery module BM, and the usage history of the battery module BM. The battery monitoring device 20 may also be configured to output battery state information to the outside using communication equipment other than the wireless communication unit 52 of the monitoring module 50.

[0161] The evaluation device 130 is configured to communicate with the battery monitoring device 20, a data center where market trading information for reused batteries is stored, and information terminals UA, UB, UC, etc., owned by users, vendors, secondary users, etc., via a wired or wireless communication network. The evaluation device 130 acquires battery status information from the battery monitoring device 20 and evaluates the battery module BM based on the battery status information. The evaluation device 130 in this embodiment includes a safety determination unit 131, a value calculation unit 132, an application suggestion unit 133, a reuse determination unit 134, and an information output unit 135.

[0162] The safety determination unit 131 determines the safety of the battery module BM based on the amount of lithium deposited in the lithium-ion batteries contained in the battery module BM. The safety determination unit 131 determines that the lower the amount of lithium deposited, the higher the safety, and that the higher the amount of lithium deposited, the lower the safety. If even one lithium battery is unsafe in the battery module BM, the safety of the battery module BM is compromised. For this reason, the safety determination unit 131 is capable of ranking the safety of each of the multiple lithium-ion batteries contained in the battery module BM based on the amount of lithium deposited.

[0163] The valuation unit 132 calculates the value of the battery module BM, taking into account the safety assessment results of the battery module BM. For example, the valuation unit 132 calculates the value assuming that a battery module BM with higher safety is more expensive than a battery module BM with lower safety.

[0164] The valuation unit 132 acquires, for example, the degradation state based on volume ratio SOH, safety based on lithium deposition amount, battery type information including application, and usage history from the battery monitoring device 20, as shown in Figure 21, and also acquires market trading information for reused batteries from the data center. The valuation unit 132 then calculates the purchase price of the battery module BM based on the degradation state, safety, battery type information, usage history, and market trading information. The valuation unit 132 calculates the purchase price of the battery module BM based on the information acquired from the battery monitoring device 20 and the data center, for example, by referring to a map that associates the degradation state, safety, battery type information, usage history, market trading information, and the purchase price of the battery module BM. The valuation unit 132 may also be configured to calculate the selling price of the battery module BM.

[0165] The application suggestion unit 133 proposes a successor application for the battery module BM when it is reused, taking into account the safety assessment results of the battery module BM. For example, as shown in Figure 21, the application suggestion unit 133 proposes a recommended application for the battery module BM when it is reused, based on the degradation state, safety, battery type information, and usage history. For example, the application suggestion unit 133 refers to a map that associates the degradation state, safety, battery type information, usage history, and reuse application, and determines a recommended application for the battery module BM when it is reused, based on the information obtained from the battery monitoring device 20.

[0166] The reuse determination unit 134 determines whether a lithium-ion battery can be reused, taking into account the safety of each of the multiple lithium-ion batteries that make up the battery module BM. For example, the reuse determination unit 134 determines that the battery can be reused if the amount of lithium deposited is below a predetermined value, and determines that it cannot be reused if the amount of lithium deposited exceeds a predetermined value.

[0167] When the information output unit 135 rebuilds a different battery by rearranging reusable lithium-ion batteries, it takes into account the safety of the lithium-ion batteries and outputs a combination of lithium-ion batteries suitable for the application of the different battery as rebuild information, as shown in Figure 22.

[0168] Here, the optimal combination of lithium-ion batteries may differ depending on how the rebuilt batteries are used. For this reason, it is desirable that the information output unit 135 outputs a combination that corresponds to the intended use of the rebuilt batteries to the rebuild system RS that manufactures the rebuilt batteries. For example, if the rebuilt batteries are to be used for a long period of time, such as in a stationary system, the information output unit 135 outputs a combination that provides a long lifespan and high safety as rebuild information. Also, if the rebuilt batteries are to be used for a short period of time, the information output unit 135 outputs a combination that prioritizes factors other than lifespan as rebuild information.

[0169] The battery evaluation system BRS and battery evaluation method described above monitor the battery state of the battery module BM and evaluate the battery module BM based on the battery state information, including the monitoring results. The battery monitoring device 20 calculates the amount of lithium deposited in the lithium-ion battery as one indicator of the battery state. The evaluation device 130 determines the safety of the battery module BM based on the amount of lithium deposited. This makes it possible to appropriately perform evaluations, including whether or not safety requirements are met, because indicators related to the safety of the battery module BM, such as the lithium deposition state, are determined.

[0170] Furthermore, the battery evaluation system BRS and battery evaluation method of this embodiment have the following features. (1) The evaluation device 130 includes a value calculation unit 132 that calculates the value of the battery module BM, taking into account the safety assessment result of the battery module BM. This allows the user to be provided with information on the appropriate value of the battery module BM.

[0171] (2) The evaluation device 130 includes an application suggestion unit 133 that proposes uses for the battery module BM when it is reused, taking into account the safety assessment results of the battery module BM. This makes it possible to provide the user with information on appropriate uses for the battery module BM.

[0172] (3) The evaluation device 130 ranks the safety of each of the multiple lithium-ion batteries contained in the battery module BM based on the amount of lithium deposited. This allows the user to be provided with information on the proper condition of the multiple lithium-ion batteries that make up the battery module BM.

[0173] (4) The evaluation device 130 includes a reuse determination unit 134 that determines whether or not a lithium-ion battery can be reused, taking into account the safety of each of the multiple lithium-ion batteries. This makes it easier to reuse the lithium-ion batteries with high safety in the battery module BM, even if the entire battery module BM cannot be reused.

[0174] (5) When rebuilding a battery separate from the battery module BM by rearranging reusable lithium-ion batteries, the evaluation device 130 takes into account the safety of the lithium-ion batteries and outputs a combination of lithium-ion batteries suitable for the application of the other battery as rebuild information. As a result, even if the entire battery module BM cannot be reused, it becomes easier to construct and reuse another storage battery using the highly safe lithium-ion batteries in the battery module BM.

[0175] (6) In addition to the amount of lithium deposited, the battery status information includes at least one of the following: the application of the lithium-ion battery, its usage history, and its degradation status. With a configuration that uses various information to evaluate the battery module BM in this way, it becomes possible to evaluate the battery module BM from multiple perspectives.

[0176] [Variations of the battery evaluation system BRS and battery evaluation method] The battery evaluation system BRS and battery evaluation method are not identical to those described above, and may differ in some respects. Furthermore, the technical matters described above can be applied to equipment and systems other than in-vehicle devices.

[0177] (Second Embodiment) Next, a second embodiment will be described with reference to Figures 23 to 25. In this embodiment, an example will be described in which the cause of a malfunction in the battery module BM is identified based on the usage history and manufacturing history of the battery module BM.

[0178] First, the manufacturing process for mounting the battery pack 1 into the vehicle will be explained with reference to Figure 23. As shown in Figure 23, the battery pack 1 is mounted into the vehicle after going through the manufacturing process of the battery cell C → the manufacturing process of the battery module BM → the manufacturing process of the battery pack 1 → the assembly process into the vehicle.

[0179] In the manufacturing process of battery cell C, electrode formation, cell assembly, electrolyte injection, initial charge / discharge, and performance testing are performed in this order. This performance testing includes, for example, visual inspection, foreign matter inspection, and battery characteristic testing of individual battery cell C using inspection equipment.

[0180] In lithium-ion batteries, lithium ions can be reduced and deposited at the negative electrode. This is especially true when charging with high current or at low temperatures, or when metallic foreign matter is mixed into the battery, causing a concentration of current density. In these cases, lithium ions released from the positive electrode active material may not be able to fully enter the negative electrode active material and are more likely to deposit on the negative electrode surface. When lithium deposits on the negative electrode, the amount of lithium ions contributing to the battery reaction decreases, which can lead to a decrease in capacity or even cause an internal short circuit.

[0181] Therefore, in the manufacturing process of battery cell C, current and temperature conditions that do not cause lithium deposition are calculated and mapped, and manufacturing measures and inspections are carried out to prevent metal foreign matter from being mixed into battery cell C. In the manufacturing process of battery cell C, for example, light is shone on the electrode surface of battery cell C to check whether or not lithium has been deposited, and the ease of lithium deposition is checked by measuring the resistance distribution on the surface of the negative electrode active material.

[0182] In the subsequent manufacturing process of the battery module BM, module assembly, in which battery cells C are assembled together, and sensor assembly, in which the sensor unit 30 and other components are attached to the battery cell C assembly, are performed. During this manufacturing process of the battery module BM, the battery monitoring device 20 is attached to the battery module BM. As a result, during the manufacturing stage of the battery module BM, the amount of lithium deposition and other parameters can be monitored by the battery monitoring device 20.

[0183] In the subsequent manufacturing process of battery pack 1, the battery modules BM are assembled together and then placed in a sealed container 11. During this process, inspections such as continuity checks are performed as appropriate.

[0184] In the subsequent vehicle assembly process, battery pack 1 is installed in the vehicle, and a vehicle inspection is conducted. The vehicle inspection includes checking for continuity with on-board equipment, etc. After that, the vehicle with battery pack 1 installed is shipped from the factory to the user.

[0185] Incidentally, it is conceivable to disassemble battery cell C and inspect the amount of lithium deposited, but this inspection method is difficult to implement on battery cells C that are actually in use or in the manufacturing process, regardless of whether it is feasible during the development stage.

[0186] In contrast, the battery monitoring device 20, as shown in Figure 24, includes a deposition amount detection unit 37 that calculates the lithium deposition amount using the output of a sensor installed on the battery module BM, and a storage unit 51 that stores the time change in the lithium deposition amount as one of the battery's usage history.

[0187] The battery monitoring device 20 stores, for example, the amount of lithium deposited in the battery module BM, the battery pack 1, and the vehicle assembly process as part of the usage history in the memory unit 51, which is a storage medium. The battery monitoring device 20 also stores the amount of lithium deposited in the battery module BM, the battery pack 1, and the vehicle assembly process as part of the manufacturing history in the memory unit 51 or an external storage device.

[0188] Furthermore, the battery monitoring device 20 includes an abnormality identification unit 544 that identifies the cause of the lithium-ion battery abnormality when an abnormality occurs in the lithium-ion battery, based on the usage history stored in the storage unit 51 and the manufacturing history stored in the storage unit 51 or an external storage device. The abnormality identification unit 544 uses the manufacturing history as reference data and compares the manufacturing history with the usage history to identify the timing of the lithium-ion battery abnormality, and identifies the cause of the lithium-ion battery abnormality by verifying the battery state before and after the timing of the abnormality. For example, as shown in Figure 25, the abnormality identification unit 544 identifies the timing of the lithium deposition increase as the timing of the lithium-ion battery abnormality.

[0189] Other aspects are the same as in the first embodiment. The battery monitoring device 20 of this embodiment can obtain the same effects as in the first embodiment, which are achieved from a configuration common to or equivalent to that of the first embodiment.

[0190] Furthermore, the battery monitoring device 20 of this embodiment has the following features. (1) The battery monitoring device 20 includes a storage unit 51 that stores the time-dependent change in the amount of lithium deposited as one of the usage or manufacturing history records of the lithium-ion battery. With this configuration, the amount of lithium deposited can be detected non-destructively and appropriately in a short time, and the lithium deposition state can be inspected. In particular, since a sensor for detecting lithium deposition is installed on the battery module BM, it is possible to detect the lithium deposition state regardless of time or place. Furthermore, by storing the time-dependent change in the amount of lithium deposited as one of the usage or manufacturing history records of the lithium-ion battery in the storage unit 51, it is possible to clearly understand when lithium deposited. This has the advantage of clearly identifying who is responsible for lithium deposition.

[0191] (2) The battery monitoring device 20 also includes an abnormality identification unit 544 that identifies the cause of the abnormality in the lithium-ion battery based on the usage history and the manufacturing history of the lithium-ion battery when an abnormality occurs in the lithium-ion battery. In this way, if the cause of the abnormality in the lithium-ion battery is identified based on historical information including not only the usage history but also the manufacturing history, the investigation of the cause of the abnormality can be traced back not only to the usage stage but also to the manufacturing stage. This greatly contributes to clarifying the locus of responsibility.

[0192] (Modified version of the second embodiment) The battery monitoring device 20 of the second embodiment is not identical to the one described above, and may differ in some respects from the one described above. Furthermore, the technical matters described in the second embodiment can be adapted to devices and systems other than in-vehicle equipment.

[0193] (Third embodiment) Next, a third embodiment will be described with reference to Figures 26 to 33. In this embodiment, an example will be described in which the battery management unit (BMU) of this disclosure is applied to a stationary, large-capacity energy storage system (BSS).

[0194] As shown in Figures 26, 27, and 28, the large-capacity energy storage system BSS comprises a housing container SC, multiple battery modules BM, a blower CM, a heater HM, a battery management unit BMU, and the like.

[0195] Each of the battery modules BM is a rechargeable battery containing a lithium-ion battery. A sensor unit 30 is installed in each of the battery modules BM. This sensor unit 30 is configured in the same way as described in the first embodiment.

[0196] The containment container SC is a container that houses multiple battery modules BM. The containment container SC is provided with openings as appropriate to ensure ventilation. The containment container SC is equipped with a blower CM and a heater HM.

[0197] The blower CM is a cooling element for the battery module BM, and generates airflow inside the housing container SC. The blower CM may be configured as a device that draws air into the housing container SC, or as a device that pushes air into the housing container SC. The operation of the blower CM is controlled according to a control signal from the battery control device 140, which will be described later.

[0198] The heater device HM is a heating element for the battery module BM and includes a heating element that generates heat when energized. The heater device HM may be configured to directly heat the battery module BM or to indirectly heat the battery module BM. The operation of the blower device CM is controlled according to a control signal from the battery control device 140, which will be described later.

[0199] The battery management unit (BMU) manages multiple battery modules (BM). The battery management unit (BMU) includes a sensor unit (30) that monitors the battery state, including the amount of lithium deposited in the lithium-ion battery, and a battery control device (140) that controls the charging of the multiple battery modules (BM).

[0200] The battery control device 140 controls the charging of multiple battery modules BM based on the battery status monitored by the sensor unit 30. The battery control device 140 charges the multiple battery modules BM using, for example, electricity obtained from solar power generation or electricity during off-peak hours when electricity rates are low.

[0201] Furthermore, the battery control device 140 is connected to the notification device ND. The battery control device 140 is configured to notify the outside of the battery status and other information monitored by the sensor unit 30 via the notification device ND.

[0202] In lithium-ion batteries, the electrode potential during charging drops to near the oxidation-reduction potential of lithium, making lithium more likely to precipitate under conditions such as low-temperature charging, high-capacity charging, and overcharging. Lithium deposition reduces the amount of available lithium ions inside the battery, causing a rapid decrease in battery capacity. Furthermore, if lithium deposition continues, it can cause an internal short circuit, and in the worst case, lead to thermal runaway of the battery.

[0203] Furthermore, if a battery malfunctions, it may become impossible to store the generated energy until a replacement is available, potentially causing significant losses for users and businesses. Therefore, in order to continue using batteries safely and securely, it is necessary to properly manage the temperature of lithium-ion batteries during charging and discharging, as well as to detect signs of battery failure such as internal short circuits early and minimize downtime.

[0204] In contrast, as shown in Figure 29, for example, if the temperature of the lithium-ion battery falls below a predetermined low-temperature threshold, it is conceivable to use the power stored in the battery as a power source and raise the temperature of the battery using a heating element such as a heater device HM.

[0205] However, the above method is a control method that focuses only on battery temperature, and depending on the battery's charge / discharge rate, it may not always be necessary to raise the battery's temperature. Furthermore, focusing only on battery temperature may lead to excessive temperature control, potentially resulting in excessive use of the power stored in the battery. In addition, in the case of large-scale energy storage facilities such as the BSS (Battery Storage System), the temperature distribution of the batteries becomes complex, making it difficult to accurately grasp the battery temperature. Moreover, temperature information alone for lithium-ion batteries makes it difficult to detect battery failures such as internal short circuits early, and operators may experience significant downtime as the system fails before they can allocate sufficient maintenance resources. Note that the charge / discharge rate refers to the speed of charging and discharging.

[0206] Taking these factors into consideration, the battery control device 140 is configured to heat the lithium-ion battery in accordance with the amount of lithium deposited during charge control. However, lithium deposition can occur even when not under charge control. Therefore, it is desirable that the battery control device 140 heats the lithium-ion battery in accordance with the amount of lithium deposited, not limited to charge control.

[0207] As shown in Figure 30, for example, when the lithium deposition amount increases beyond the first deposition threshold Hi, the battery control device 140 starts supplying power to the heater device HM to heat the battery module BM. Heating the battery module BM reduces the lithium deposition amount. Then, when the lithium deposition amount falls below the second deposition threshold Lo, which is smaller than the first deposition threshold Hi, the battery control device 140 stops supplying power to the heater device HM and stops heating the battery module BM.

[0208] As mentioned above, lithium deposition occurs not only during low-temperature charging, but also in situations such as high-capacity charging and overcharging. In situations such as high-capacity charging and overcharging, the battery temperature of the battery module BM may be somewhat high.

[0209] Therefore, the battery control device 140 may be configured to heat the lithium-ion battery according to the amount of lithium deposited and the temperature of the battery module BM. For example, as shown in Figure 31, the battery control device 140 may be configured to energize the heater device HM to heat the battery module BM when the amount of lithium deposited increases beyond a first deposition threshold Hi and the battery temperature of the battery module BM falls below a predetermined low-temperature threshold.

[0210] Furthermore, the battery control device 140 is configured to restrict charging and discharging of the battery module BM or to notify an external party of the battery abnormality via the notification device ND if the battery temperature of the battery module BM exceeds a low-temperature threshold and the amount of lithium deposited exceeds a first deposition threshold Hi.

[0211] In order to minimize downtime, it is desirable to replace the battery during the period from when the battery's volume fraction (SOH) decreases to a certain extent due to degradation, as shown in Figure 32, until the amount of lithium deposited reaches a level that causes an internal short circuit in the battery.

[0212] Taking this into consideration, the battery control device 140 of this embodiment estimates a desirable battery replacement period from the change in volume fraction SOH and the change in lithium deposition amount output by the sensor unit 30, and notifies the outside of the system of this recommended battery replacement period via the notification device ND. As a result, businesses and others can know the recommended battery replacement period, making it possible to reduce downtime due to maintenance or system failures, including battery failures.

[0213] Other aspects are the same as in the first embodiment. The battery management unit (BMU) of this embodiment can obtain the same effects as in the first embodiment, which are achieved from a configuration common to or equivalent to that of the first embodiment.

[0214] Furthermore, the battery management unit (BMU) of this embodiment has the following features. (1) When the amount of lithium deposited increases beyond a predetermined threshold, the battery management unit (BMU) heats the battery module BM with a heater device (HM) that raises the temperature of the battery module BM. This allows the lithium-ion battery to be heated at the time the amount of lithium deposited increases, thereby appropriately suppressing the increase in lithium deposited amount, and enabling the lithium-ion battery to be used in a safe and highly efficient manner. In particular, the battery management unit of this invention is suitable for large-scale energy storage facilities where the temperature distribution tends to expand.

[0215] (2) The sensor unit 30 includes a temperature sensor 31 for detecting the battery temperature of the lithium-ion battery. The battery control device 140 may be configured to heat the battery module BM with a heater device HM when the amount of lithium deposited increases beyond a predetermined threshold and the battery temperature falls below a predetermined low-temperature threshold. This also allows the lithium-ion battery to be used in a safe and highly efficient manner.

[0216] (Modified version of the third embodiment) In the third embodiment, the battery management unit (BMU) of the large-capacity energy storage system (BSS) was described in detail, but the battery management unit (BMU) may not be identical to the one described above and may differ in some respects from the one described above.

[0217] Furthermore, the technical aspects described in the third embodiment can be adapted to equipment and systems other than the large-capacity energy storage system (BSS). The battery management unit (BMU) can, for example, be adapted for power management of mobile devices such as vehicles.

[0218] In the third embodiment, the heating element is configured as a heater device HM, but it is not limited to this, and the heating element may be configured as a load device located around the battery. Furthermore, the heating element may be heated by power supplied from a source other than the battery module BM.

[0219] Here, the amount of lithium deposited tends to be higher when the battery temperature is low and the charging rate is high, and lower when the battery temperature is high and the charging rate is low. Thus, there is a certain correlation between the amount of lithium deposited, the charging rate, and the battery temperature. For this reason, the deposit amount detection unit 37 may calculate the amount of lithium deposited by referring to a control map that defines the correlation between the amount of lithium deposited, the charging rate, and the battery temperature, for example, as shown in Figure 33. This is also true for embodiments other than this one.

[0220] (Fourth Embodiment) Next, a fourth embodiment will be described with reference to Figures 34 and 35. In this embodiment, a battery transport device BSC that transports batteries in a containment container SC will be described.

[0221] Lithium-ion batteries contain toxic and flammable chemicals, so they must be transported safely. For example, air transport is subject to international regulations regarding packaging standards depending on the lithium content. Battery packs used in electric vehicles have a high lithium content, making air transport legally difficult, and sea transport by ship is common. Compared to air transport, sea transport is much longer. For example, in summer, transport may be in high temperature and humidity conditions for extended periods, while in winter, it may be in low temperature conditions for extended periods. Under such stressful conditions, if a lithium-ion battery enters an unsafe state, it can become difficult to control, potentially harming other cargo or crew members. Therefore, it is crucial to monitor the safety status of lithium-ion batteries.

[0222] In contrast, it is conceivable to transport lithium-ion batteries using a transport container made of non-combustible material and equipped with a cooling mechanism, and to deactivate the lithium-ion battery using the cooling mechanism when an unsafe event is detected in the battery using a gas sensor 35.

[0223] However, the chemical reaction that leads to an unsafe state in a lithium-ion battery is an exothermic chain reaction. As described above, when using the gas sensor 35 to detect an unsafe event in the battery, the chain reaction has already begun the moment gas is released from the lithium-ion battery. Because the chain reaction proceeds rapidly, it is difficult to deactivate the lithium-ion battery at this point. Furthermore, the released gas is harmful and could potentially harm the cargo or crew.

[0224] Taking these factors into consideration, the battery transport device BSC of this embodiment is configured to monitor factors that lead to an abnormal heat generation phenomenon in which the battery temperature continues to rise unintentionally, and to detect abnormal conditions that occur in the battery in the initial stages of the abnormal heat generation phenomenon based on the monitoring results.

[0225] As shown in Figure 34, the battery transport equipment BSC comprises a housing container SC that houses multiple battery modules BM, a sensor unit 30A that detects the battery status of the multiple battery modules BM, and an abnormality detection unit 150.

[0226] As shown in Figure 35, the sensor unit 30A includes a humidity sensor HS and an acceleration sensor GS, in addition to the temperature sensor 31, gas sensor 35, and precipitate amount detection unit 37 described in the first embodiment. The humidity sensor HS is installed inside the containment container SC to detect the humidity inside the containment container SC. The acceleration sensor GS is set inside the containment container SC to detect vibrations and shocks applied to the containment container SC. Note that the sensor unit 30A may also include other sensors.

[0227] The sensor unit 30A of this embodiment includes a wireless communication device (not shown) for wireless communication with the anomaly detection unit 150. The sensor unit 30A may also include a communication device for wired communication with the anomaly detection unit 150.

[0228] The abnormality detection unit 150 prevents the occurrence of abnormal heat generation based on the monitoring results of factors that lead to abnormal heat generation, and also detects abnormal conditions that occur in the battery in the initial stages of abnormal heat generation, and implements countermeasures against abnormal heat generation based on the detection results of the abnormal conditions. The abnormality detection unit 150 is configured in the same way as the monitoring module 50 described in the first embodiment. That is, the abnormality detection unit 150 includes a storage unit 51, a wireless communication unit 52, an internal resistance detection unit 53, a monitoring IC 54, etc.

[0229] The abnormality detection unit 150 executes the control process shown in Figure 12, described in the first embodiment, in order to prevent and detect abnormal heat generation phenomena early. In addition, the abnormality detection unit 150 implements measures against abnormal heat generation phenomena, such as the external notification process and battery protection process described in the first embodiment.

[0230] In the external notification process, a signal indicating the occurrence of an abnormal overheating phenomenon is output to the notification device ND, and the occurrence of the abnormal overheating phenomenon is notified externally via the notification device ND. In this external notification process, it is desirable that at least one of the following is notified externally: for example, the sensor output of the temperature sensor 31, the humidity sensor HS, the acceleration sensor GS, and the location information of the battery module BM where the abnormal overheating phenomenon occurred. This is because it makes it easier to clarify who is responsible for the occurrence of the abnormal overheating phenomenon. The location information of the battery module BM can be information identified based on, for example, the radio wave strength of the signal emitted by the sensor unit 30A.

[0231] Other aspects are the same as in the first embodiment. The battery transport device BSC of this embodiment can obtain the same effects as in the first embodiment, which are achieved from a configuration common to or equivalent to that of the first embodiment.

[0232] Furthermore, the battery transport device BSC of this embodiment has the following features. (1) The battery transport equipment BSC comprises a containment container SC, a factor monitoring unit that monitors factors leading to an abnormal heat generation phenomenon in which the battery temperature continues to rise unintentionally, and an abnormality detection unit 150 that detects abnormalities in the battery. The abnormality detection unit 150 suppresses the occurrence of the abnormal heat generation phenomenon based on the monitoring results of the factor monitoring unit, and also detects abnormal conditions that occur in the battery in the initial stages of the abnormal heat generation phenomenon, and implements countermeasures against the abnormal heat generation phenomenon based on the detection results of the abnormal condition. This makes it possible to implement effective thermal countermeasures when transporting batteries, such as preventing the occurrence of the abnormal heat generation phenomenon from happening in the first place, and even if the abnormal heat generation phenomenon does occur, countermeasures can be implemented from the initial stages of its occurrence.

[0233] (Modification of the fourth embodiment) In the fourth embodiment, the battery transport equipment BSC was described in detail, but the battery transport equipment BSC is not identical to the one described above and may differ in some respects. Furthermore, the technical matters described in the fourth embodiment can be applied to equipment and systems other than the battery transport equipment BSC. (Other embodiments) While typical embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above and can be modified in various ways, for example, as follows.

[0234] The battery monitoring device 20 in this proposal is essential for detecting the amount of lithium deposited in lithium-ion batteries, but it is not essential for measures to prevent abnormal heat generation in batteries or for estimating the battery's volume fraction (SOH).

[0235] In the embodiments described above, the amount of lithium deposition and the internal resistance of the battery were given as examples of factors that could lead to abnormal heat generation. However, other physical quantities may also be monitored as factors that could lead to abnormal heat generation.

[0236] In the above-described embodiment, several processes were exemplified as countermeasures against abnormal heat generation, but the battery monitoring device 20 may perform some of these processes. Furthermore, countermeasures against abnormal heat generation may include processes other than those described above.

[0237] In the embodiments described above, examples of abnormal conditions occurring in the battery at the initial stage of the abnormal heat generation phenomenon were given as abnormal pressure in the sealed container 11, abnormal battery temperature, abnormal battery voltage, and abnormal gas in the sealed container 11, but the system is not limited to these. Other battery conditions may also be detected as abnormal conditions occurring at the initial stage of the abnormal heat generation phenomenon.

[0238] The battery monitoring device 20 described above includes, but is not limited to, a flexible printed circuit board (FPC) and an ASIC circuit. A flexible printed circuit board (FPC) and an ASIC circuit are not essential components of the battery monitoring device 20.

[0239] As described in the above embodiment, it is desirable that the battery monitoring device 20 corrects the estimated lithium deposition amount with the battery temperature or parasitic resistance value, but this is not required.

[0240] As described in the above embodiment, it is desirable that the battery monitoring device 20 compares a predetermined battery state estimated from the lithium deposition amount with a predetermined battery state estimated from other factors to diagnose whether the deposition amount detection unit 37 is appropriate, but it is not required to be so.

[0241] In the above-described embodiment, an example was given in which the volume fraction SOH is estimated based on the amount of lithium deposited and the thickness of the SEI layer of the battery, but the volume fraction SOH may be estimated based on other physical quantities. The battery monitoring device 20 may, for example, detect a degradation state including cracking of the positive electrode of the battery and calculate the volume fraction SOH based on that degradation state.

[0242] As described in the above embodiment, it is desirable that the battery monitoring device 20, together with the battery management device 60, be able to constitute a battery management system BMS for managing the battery module BM, but this is not required. The same applies to the charging system BCS and the battery evaluation system BRS. The battery evaluation system BRS may be configured as one of the functional units in the battery management system BMS.

[0243] The battery monitoring device 20 is not limited to monitoring on-board batteries installed in vehicles. The battery monitoring device 20 can also be used to monitor stationary batteries, portable batteries, and so on.

[0244] The battery monitoring device 20 primarily monitors lithium-ion batteries, but it is not limited to lithium-ion batteries. It can also monitor other types of batteries that may have similar problems to lithium-ion batteries. The batteries monitored by the battery monitoring device 20 do not necessarily have to be modules of multiple battery cells C.

[0245] The battery monitoring device 20 may be connected to the battery ECU 100 by a wired connection rather than wirelessly. The battery monitoring device 20 is not limited to being exactly the same as described above, and may differ in part from the described above.

[0246] In the embodiments described above, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where they are explicitly stated to be essential or where they are clearly considered essential in principle.

[0247] In the embodiments described above, if numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiment are mentioned, the embodiment is not limited to those specific numbers unless explicitly stated as particularly essential or clearly limited to a specific number in principle.

[0248] In the embodiments described above, when referring to the shape, positional relationships, etc. of the components, the definition is not limited to those shapes, positional relationships, etc., unless otherwise specifically stated or when the definition is fundamentally limited to a particular shape, positional relationship, etc.

[0249] The control unit and its method of this disclosure may be implemented in a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. The control unit and its method of this disclosure may be implemented in a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. The control unit and its method of this disclosure may be implemented in one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. The computer program may also be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium.

[0250] [Features of this disclosure] This disclosure has the following features. [Disclosure 1] A battery monitoring device for monitoring the amount of lithium deposited in a lithium-ion battery, The lithium-ion battery includes a short-circuit circuit (371) that temporarily short-circuits both ends of the lithium-ion battery to discharge it, and a deposition amount detection unit (37) that calculates an estimated value of the lithium deposition amount based on the change in at least one of the current and voltage when the lithium-ion battery is short-circuited by the short-circuit circuit, The system includes a temperature sensor (31) for detecting the battery temperature of the lithium-ion battery, The aforementioned deposition amount detection unit calculates a corrected value obtained by correcting the estimated value with respect to the battery temperature as the lithium deposition amount, and is a battery monitoring device.

[0251] [Disclosure 2] A battery monitoring device for monitoring the amount of lithium deposited in a lithium-ion battery, It includes a short - circuit circuit (371) that temporarily shorts both ends of the lithium - ion battery to discharge it, and a precipitation amount detection unit (37) that calculates an estimated value of the lithium precipitation amount based on at least one of the changes in current and voltage when both ends of the lithium - ion battery are short - circuited by the short - circuit circuit. It is provided with a storage unit (51) in which a parasitic resistance value generated between the lithium - ion battery and the short - circuit circuit is stored in advance. The precipitation amount detection unit calculates a correction value obtained by correcting the estimated value with the parasitic resistance value as the lithium precipitation amount, and it is a battery monitoring device.

[0252] [Disclosure 3] It is provided with a temperature sensor (31) that detects the battery temperature of the lithium - ion battery. The precipitation amount detection unit calculates a correction value obtained by correcting the estimated value using both the parasitic resistance value and the battery temperature as the lithium precipitation amount, and it is the battery monitoring device according to Disclosure 2.

[0253] [Disclosure 4] The precipitation amount detection unit corrects the parasitic resistance value stored in the storage unit according to the battery temperature, and calculates the lithium precipitation amount using the corrected parasitic resistance value, and it is the battery monitoring device according to Disclosure 3.

[0254] [Disclosure 5] The parasitic resistance value is obtained by connecting to a calibration device having a known impedance before connecting the short - circuit circuit to the lithium - ion battery, and it is the battery monitoring device according to any one of Disclosures 2 to 4.

[0255] [Disclosure 6] It is provided with a diagnosis unit (541) that compares a predetermined battery state estimated from the lithium precipitation amount with the battery state estimated from other elements other than the lithium precipitation amount, and diagnoses the suitability of the precipitation amount detection unit, and it is the battery monitoring device according to any one of Disclosures 1 to 5.

[0256] [Disclosure 7] A battery monitoring device for monitoring the amount of lithium precipitation in a lithium-ion battery, comprising a short-circuit circuit (371) that temporarily shorts and discharges both ends of the lithium-ion battery, and a precipitation amount detection unit (37) that calculates an estimated value of the lithium precipitation amount based on at least one change in current and voltage when both ends of the lithium-ion battery are short-circuited by the short-circuit circuit; a diagnosis unit (541) that compares a predetermined battery state estimated from the lithium precipitation amount with the battery state estimated from other elements other than the lithium precipitation amount, and diagnoses the suitability of the precipitation amount detection unit; A battery monitoring device comprising:

[0257] [Disclosure 8] The battery monitoring device according to any one of Disclosures 1 to 7, further comprising a storage medium (51) that stores the temporal change of the lithium precipitation amount as one of the usage history or the manufacturing history of the lithium-ion battery.

[0258] [Disclosure 9] A battery monitoring device for monitoring the amount of lithium precipitation in a lithium-ion battery, comprising a precipitation amount detection unit (37) that calculates the lithium precipitation amount using the output of a sensor installed in a storage battery including the lithium-ion battery, and a storage unit (51) that stores the temporal change of the lithium precipitation amount as one of the usage history or the manufacturing history of the lithium-ion battery. A battery monitoring device comprising:

[0259] [Disclosure 10] The battery monitoring device according to Disclosure 8 or 9, further comprising an abnormality specifying unit (544) that specifies the cause of the abnormality based on the usage history and the manufacturing history when an abnormality occurs in the lithium-ion battery.

[0260] [Disclosure 11] [[ID=3才4]]When the lithium precipitation amount increases beyond a predetermined threshold value, the lithium-ion battery is heated by a heating element (HM) that raises the temperature of the lithium-ion battery. The battery monitoring device according to any one of Disclosures 1 to 9.

[0261] [Disclosure 12] A battery management unit that manages storage batteries, including lithium-ion batteries, A sensor unit (30) that monitors the battery state, including the amount of lithium deposited in the lithium-ion battery, The battery control device (140) is provided for controlling the charging of the aforementioned storage battery, The battery control device is a battery management unit that, when the amount of lithium deposited increases beyond a predetermined threshold, heats the battery with a heating element (HM) that raises the temperature of the battery.

[0262] [Disclosure 13] The sensor unit includes a temperature sensor (31) that detects the battery temperature of the lithium-ion battery. The battery control device, during the charging control, heats the storage battery with the heating element when the amount of lithium deposition increases beyond a predetermined threshold and the battery temperature falls below a predetermined low-temperature threshold, as described in Disclosure 12. [Explanation of Symbols]

[0263] 20 Battery monitoring device 31 Temperature sensor 37. Precipitation amount detection unit 371 Short Circuit

Claims

1. A battery monitoring device for monitoring the amount of lithium deposited in a lithium-ion battery, A deposition amount detection unit (37) that calculates the lithium deposition amount using the output of a sensor installed in the storage battery including the lithium-ion battery, A storage unit (51) that stores the time change in the amount of lithium deposited during the manufacturing process of the lithium-ion battery as one of the manufacturing history records, and stores the time change in the amount of lithium deposited during use of the lithium-ion battery as one of the usage history records, A battery monitoring device comprising: an abnormality identification unit (544) that identifies the cause of an abnormality when an abnormality occurs in the lithium-ion battery, based on both the usage history and the manufacturing history stored in the storage unit.

2. The battery monitoring device according to claim 1, wherein when the amount of lithium deposited increases beyond a predetermined threshold, the lithium-ion battery is heated by a heating element (HM) that raises the temperature of the lithium-ion battery.

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