vehicle

Abstract

This system provides the ability to acquire data on the internal state of a battery, such as SOC-OCV characteristics and FCC, with high accuracy, even after repeated charging and discharging over long periods, and to enable highly accurate estimation. [Solution] A battery management system having a vehicle equipped with means for sending and receiving data, wherein the vehicle has a battery, a balance circuit electrically connected to the battery, and a vehicle control unit having a function to control the balance circuit, the battery has a battery pack having a plurality of battery cells, the vehicle control unit has a function to select the closest estimated value to the state of the battery cells in the battery pack, and the balance circuit has a function to be controlled based on the selected estimated value.

Description

Technical Field

[0001] One aspect of the present invention relates to a battery management system. Further, one aspect of the present invention relates to a server device or a computer program used in a battery management system. Also, one aspect of the present invention relates to a battery management system using a neural network.

[0002] Also, one aspect of the present invention relates to a vehicle equipped with a battery management system. Also, one aspect of the present invention relates to an electronic device equipped with a battery management system. Further, not limited to vehicles and electronic devices, one aspect of the present invention relates to a power storage device for storing electric power obtained from power generation equipment such as a solar power generation panel.

[0003] Note that one aspect of the present invention is not limited to the above technical field, and relates to semiconductor devices, display devices, light-emitting devices, recording devices, their driving methods, or their manufacturing methods. That is, the technical field of one aspect of the invention disclosed in this specification and the like relates to objects, methods, or manufacturing methods.

Background Art

[0004] A storage battery represented by a lithium-ion secondary battery has become indispensable in modern society as an energy source that can be repeatedly used. While a lithium-ion secondary battery has high output and high energy density, it is known to have a high safety risk associated with over-discharge and over-charging. Therefore, when using a lithium-ion secondary battery, it is required to grasp or manage the internal state of the battery such as the charge rate and internal resistance.

[0005] As estimation methods for grasping the internal state, the Coulomb counting method, the open circuit voltage (OCV) method, or the Kalman filter are known (see, for example, Patent Document 1). In estimation methods such as the Kalman filter, it is important to obtain data regarding the internal state of the storage battery, for example, the state of charge (SOC)-OCV characteristics and the full charge capacity (FCC), with high accuracy.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] Although not considered in Patent Document 1 above, repeated charging and discharging over a long period may cause deterioration of the storage battery. Furthermore, errors may accumulate in the measured values of the storage battery. As a result, there was a risk that the data accuracy regarding the internal state such as the SOC-OCV characteristics and the FCC would decrease. Also, by managing the storage battery in a state where the data accuracy regarding the internal state is low, the estimation accuracy may also become low, and as a result, there was a risk of accelerating the deterioration of the storage battery or leading the storage battery to a dangerous state.

[0008] For example, in order to obtain highly accurate SOC-OCV characteristic data, it is desirable to acquire a large number of data. Acquiring a large number of data includes collecting the number of data over time. However, increasing the number of data may result in a data capacity that exceeds the processing capacity as data used by the control unit or storage unit of the storage battery or a vehicle equipped with the storage battery, etc., and there was also concern about insufficient computing power. The estimation process, etc. in such a situation takes time, and there is also concern about a decrease in the estimation accuracy.

[0009] Therefore, one aspect of the present invention aims to provide a battery management system, vehicle, or server device that enables highly accurate estimation of the internal state of a battery, such as SOC-OCV characteristics and FCC, even when charging and discharging are repeated over a long period of time.

[0010] Another aspect of the present invention aims to provide a system or method that enables highly accurate estimation of the above-mentioned storage battery in a short amount of time.

[0011] Furthermore, the description of these problems does not preclude the existence of other problems. Moreover, one aspect of the present invention does not need to solve all of these problems. Furthermore, it is possible to extract other problems from the description in the specification, drawings, and claims (referred to as "specification, etc."). [Means for solving the problem]

[0012] One aspect of the present invention is a battery management system having a vehicle equipped with means for transmitting and receiving data, wherein the vehicle has a battery, a balance circuit electrically connected to the battery, and a vehicle control unit having a function for controlling the balance circuit, the battery has a battery pack having a plurality of battery cells, the vehicle control unit has a function for selecting the closest estimated value to the state of the battery cells in the battery pack, and the balance circuit has a function for being controlled based on the selected estimated value.

[0013] Furthermore, one aspect of the present invention is a battery management system comprising a server device and a vehicle equipped with means for sending and receiving data with the server device, wherein the vehicle comprises a battery, a balance circuit electrically connected to the battery, and a vehicle control unit having a function for controlling the balance circuit, the battery comprises a battery pack having a plurality of battery cells, the server device has a function for calculating at least two or more estimated values ​​based on first data relating to the internal state of the battery pack transmitted from the vehicle, and a function for transmitting the two or more estimated values ​​to the vehicle, the vehicle control unit has a function for selecting the estimated value that is closest to the state of the battery cells in the battery pack from among the two or more estimated values, and the balance circuit has a function for being controlled based on the selected estimated value.

[0014] In the battery management system described in any one of the above, it is preferable that the first data includes sequential data relating to the internal state of the battery pack.

[0015] In the battery management system described in any one of the above, it is preferable that the sequential data includes SOC-OCV characteristics.

[0016] In the battery management system described in any one of the above, it is preferable that the sequential data includes internal resistance.

[0017] In the battery management system described in any one of the above, the internal resistance preferably includes a fast-responding resistance component R1 and a slow-responding resistance component R2.

[0018] In the battery management system described in any one of the above, it is preferable that the server device has a function to predict changes in the fast-responding resistance component R1 and the slow-responding resistance component R2 using LSTM (Long Short-Term Memory).

[0019] Furthermore, one aspect of the present invention is a vehicle comprising a storage battery, a balance circuit electrically connected to the storage battery, and a vehicle control unit having a function to control the balance circuit, wherein the storage battery comprises a battery pack having a plurality of battery cells, the vehicle control unit has a function to select the estimate that is closest to the state of each battery cell in the battery pack from two or more estimates transmitted from a server device, and the balance circuit has a function to be controlled based on the selected estimate.

[0020] In any of the vehicles described above, it is preferable that the server device has sequential data regarding the internal state of the battery pack transmitted from the vehicle.

[0021] In any of the vehicles described above, it is preferable that the sequential data includes SOC-OCV characteristics.

[0022] In any of the vehicles described above, it is preferable that the sequential data includes internal resistance.

[0023] In any of the vehicles described above, the internal resistance preferably includes a fast-responding resistance component R1 and a slow-responding resistance component R2.

[0024] In any of the vehicles described above, it is preferable that the internal resistance is measured by each of the multiple battery cells.

[0025] In any of the vehicles described above, it is preferable that the vehicle has a function for measuring internal resistance using the current pause method.

[0026] Furthermore, one aspect of the present invention is a server device having the function of receiving first data relating to the internal state of battery cells in a battery pack transmitted from a vehicle having a battery pack, the function of calculating at least two or more estimated values ​​using the first data and a first algorithm, and the function of transmitting the two or more estimated values ​​to the vehicle.

[0027] In the server device described in any one of the above, it is preferable that the first data includes sequential data relating to the internal state of the battery pack.

[0028] In the server device described in any one of the above, it is preferable that the sequential data includes SOC-OCV characteristics.

[0029] In the server device described in any one of the above, it is preferable that the sequential data includes internal resistance.

[0030] In the server device described in any one of the above, the internal resistance preferably includes a fast-responding resistance component R1 and a slow-responding resistance component R2.

[0031] In the server device described in any one of the above, it is preferable that it has a function to predict changes in the fast-responding resistance component R1 and the slow-responding resistance component R2 using an LSTM. [Effects of the Invention]

[0032] This invention enables highly accurate and rapid estimation of the internal state of a battery. Furthermore, even when the battery has a battery pack, highly accurate and rapid estimation of the internal state of the battery is possible.

[0033] Furthermore, the description of these effects does not preclude the existence of other effects. Moreover, one aspect of the present invention does not necessarily have to possess all of these effects. Other effects will naturally become apparent from the description in the specification, drawings, and claims, and it is possible to extract other effects from the description in the specification, drawings, and claims. [Brief explanation of the drawing]

[0034] [Figure 1] Figures 1A and 1B are conceptual diagrams of a battery storage system according to one aspect of the present invention. [Figure 2] Figure 2 is a conceptual diagram of a vehicle according to one aspect of the present invention. [Figure 3] Figure 3 illustrates a balancing process or balancing circuit, which is one embodiment of the present invention. [Figure 4] Figure 4 is a diagram illustrating a method for processing SOC-OCV characteristic data, which is one aspect of the present invention. [Figure 5] Figure 5 illustrates a description method for SOC-OCV characteristic data according to one aspect of the present invention. [Figure 6] Figure 6 illustrates a method for processing FCC and internal resistance, which is one aspect of the present invention. [Figure 7] Figure 7 illustrates a method for estimating internal resistance, which is one aspect of the present invention. [Figure 8] Figure 8 shows the analysis method for current pause measurement. [Figure 9] Figures 9A and 9B show examples of analysis results from current pause method measurements. [Figure 10] Figures 10A to 10C illustrate a positive electrode according to one embodiment of the present invention. [Figure 11] Figures 11A and 11B illustrate an all-solid-state secondary battery according to one embodiment of the present invention. [Figure 12] Figure 12 is a diagram illustrating a method for producing a positive electrode active material according to one aspect of the present invention. [Figure 13] Figure 13 is a diagram illustrating a method for producing a positive electrode active material according to one aspect of the present invention. [Figure 14] Figure 14 is a diagram illustrating a method for manufacturing a secondary battery according to one aspect of the present invention. [Figure 15] Figures 15A and 15B illustrate the appearance of a secondary battery according to one embodiment of the present invention. [Figure 16] Figures 16A to 16C illustrate the appearance of a secondary battery according to one embodiment of the present invention. [Figure 17] Figures 17A to 17C illustrate the appearance of a secondary battery according to one embodiment of the present invention. [Figure 18] Figures 18A to 18D illustrate the appearance of a secondary battery according to one embodiment of the present invention. [Figure 19] Figures 19A to 19D illustrate a vehicle according to one embodiment of the present invention. [Modes for carrying out the invention]

[0035] The following describes embodiments for carrying out the present invention with reference to drawings and other illustrations. However, the present invention is not limited to the following embodiments. It is possible to modify the embodiments for carrying out the invention without departing from the spirit of the present invention.

[0036] In this specification, crystal planes and crystal directions are indicated using Miller indices. Individual crystal planes are indicated using parentheses ( ). In crystallography, crystal planes, crystal directions, and space groups are indicated by a bar above the number; however, due to formatting constraints in this specification, a minus sign (-) may be placed before the number instead of a bar above it.

[0037] In this specification, the theoretical capacity of the positive electrode active material refers to the amount of electricity when all of the insertable and detachable lithium present in the positive electrode active material has been detached. For example, the theoretical capacity of LiCoO2 is 274 mAh / g, the theoretical capacity of LiNiO2 is 275 mAh / g, and the theoretical capacity of LiMn2O4 is 148 mAh / g.

[0038] In this specification, the term "storage battery" refers to all elements and devices that have an energy storage function. This includes, for example, secondary batteries such as lithium-ion secondary batteries, lithium-ion capacitors, and electric double-layer capacitors.

[0039] In this specification, the term "energy storage device" includes devices for storing electricity obtained from power generation equipment such as solar power generation panels.

[0040] In this specification, "electronic equipment" refers to all devices that have a rechargeable battery, and all electro-optical devices and information terminal devices that have a rechargeable battery are considered electronic equipment.

[0041] In this specification, the term "semiconductor device" refers to an element, circuit, or device that functions by utilizing semiconductor properties. For example, semiconductor elements such as transistors and diodes are semiconductor devices. Another example is a circuit having a semiconductor element. Yet another example is a device equipped with a circuit having a semiconductor element.

[0042] (Embodiment 1) This embodiment describes a battery storage system according to one aspect of the present invention.

[0043] Figures 1A and 1B are conceptual diagrams of a battery management system. The battery management system comprises a server device 1 and a vehicle 3 equipped with a battery pack (also called a battery pack) 4 having multiple battery cells, and a means for sending and receiving data with the server device 1. In this battery management system, the server device 1 can perform estimation of the internal state of the battery cells, and the vehicle 3 can receive the results. In other words, the estimation of the internal state of the battery cells, which was conventionally performed on the vehicle 3 side, can be performed by the server device 1. To have the server device 1 perform estimation regarding the internal state of the battery cells, it is preferable to sequentially transmit data regarding the internal state of the battery cells (including measured data or estimated data) from the vehicle 3 to the server device 1. Sequentially transmitted data is sometimes referred to as sequential data. Sequential data consists of a large number of data, but it is recorded, i.e., stored, by the server device 1, so it does not place a burden on the storage unit on the vehicle 3 side. Furthermore, it is desirable that there be two or more data (sometimes referred to as estimated values) estimated by the server device 1 based on the sequential data for each battery cell. Since the estimation process is performed on server device 1, estimation can be performed even while driving, allowing sufficient time for estimation. Furthermore, considering the computing power of server device 1, it is possible to calculate two or more estimated values. Subsequently, two or more estimated values ​​are transmitted from server device 1 to vehicle 3, and vehicle 3 can select the optimal one from the two or more estimated values. Vehicle 3 does not perform estimation processing and selects the received estimated value. Note that the estimated value that was not selected may contain an error, which is the reason why vehicle 3 made that decision. Vehicle 3 can return multiple pieces of information to server device 1, including the selected estimated value, the not selected estimated value, and information about the error. With such a system, estimation processing regarding the internal state of the battery can be performed with high accuracy and in a short time. Moreover, it is desirable that the accuracy of the estimated values ​​improves as the transmission and reception of estimated values ​​between server device 1 and vehicle 3 is repeated multiple times.

[0044] The battery cell's current, voltage, and temperature can be measured by sensors on vehicle 3. For example, the battery cell's current can be measured as an integrated value using Coulomb counts. These measured values ​​can be used to estimate the internal state of the battery cell. Estimating the internal state includes estimating the SOC-OCV characteristics, FCC, or internal resistance (R). When estimating the SOC-OCV characteristics, the battery management system can be described as a battery SOC estimation system.

[0045] Server device 1 can perform one or more of the above-described estimations of the internal state. Estimations not performed by server device 1 may be performed on vehicle 3. For example, the estimation of internal resistance (R), which does not burden the amount of data, may be performed on vehicle 3.

[0046] Figure 1B is a conceptual diagram illustrating the use of a battery management system in multiple vehicles. These multiple vehicles may be of the same model or different models.

[0047] Server device 1 preferably performs functions such as a cloud server, an AI (Artificial Intelligence) server, or a GPU (Graphics Processing Unit) server. Server device 1 preferably has an algorithm with a neural network, and the battery management system can be described as a battery management system with artificial intelligence. In addition to a GPU, it is preferable to have a CPU (Central Processing Unit). Having a GPU or CPU enables high-speed computation processing.

[0048] The battery pack 4 has multiple battery cells (so-called battery packs). Because the battery pack 4 has multiple battery cells, the sequential data regarding its internal state becomes enormous. However, in one embodiment of the present invention, this data can be recorded, i.e., stored, in the server device 1. Furthermore, since the server device 1 can perform estimation processing based on this data, it is preferable that there is no burden on the control unit or storage unit on the vehicle 3 side.

[0049] Server device 1 and vehicle 3 can send and receive data from each other via the communication network 7. That is, server device 1 and vehicle 3 each have communication means corresponding to the communication network 7. Data can be sent and received at any time, but it is preferable to do so during the vehicle 3's charging period. During the charging period, server device 1 should perform estimation processing and send and receive estimated values.

[0050] The server device 1 and the vehicle 3 may not only communicate data directly on a one-to-one basis, but may also use data communication via charger 2, electronic devices (including battery devices owned by the passenger), internet lines, communication relay devices, and communication base stations. The data communication method for the communication network 7 may be wired communication or wireless communication. When using wireless communication, wireless communication in accordance with communication standards such as the fourth-generation mobile communication system (4G) or the fifth-generation mobile communication system (5G) may be used. The signal frequencies for wireless communication may include any of the following frequencies: submillimeter wave (300 GHz to 3 THz), millimeter wave (30 GHz to 300 GHz), microwave (3 GHz to 30 GHz), ultra-high frequency wave (300 MHz to 3 GHz), very high frequency wave (30 MHz to 300 MHz), short wave (3 MHz to 30 MHz), medium wave (300 kHz to 3 MHz), long wave (30 kHz to 300 kHz), and very low frequency wave (3 kHz to 30 kHz).

[0051] The charger 2 may have the above-mentioned communication means that are compatible with the communication network 7 for sending and receiving data.

[0052] As shown in Figures 1A and 1B, the data includes first data 11 sent from vehicle 3 to server device 1 and second data 12 sent from server device 1 to vehicle 3.

[0053] The first data 11 relates to the battery cells of the battery pack 4 and includes data measured by the vehicle 3's sensors, or data estimated based on the measured data. The types of data related to the battery pack 4 include FCC, internal resistance (R), and SOC-OCV characteristic data. In addition, the data may include the cumulative charge amount. The cumulative charge amount of the battery pack 4 is either the cumulative charge amount since it was installed in the vehicle 3, or the cumulative charge amount since the last data transmission, or both. If both are included, there will be two data points indicating the cumulative charge amount of the battery pack 4. The first data 11 may also include error data.

[0054] The second set of data 12 pertains to the battery pack 4 and includes estimated data (estimated values). The estimated values ​​for the battery pack 4 include FCC, internal resistance (R) value, SOC-OCV characteristic data, and cumulative charge amount.

[0055] The estimated second data 12 preferably has two or more estimated values. For example, estimated SOC-OCV characteristic data A and estimated SOC-OCV characteristic data B. In such a case, the vehicle 3 can select either data A or data B to use as an estimated value for the SOC-OCV of the battery pack 4, and balancing processing is performed as needed using this estimated value.

[0056] The first data 11 and the second data 12 can also be transmitted and received between the server device 1 and the vehicle 3 without going through the charger 2, and the vehicle 3 may have a means of communication.

[0057] Figure 1B shows multiple first data sets (first data 11a and second data 11b) sent to the server device 1 from multiple chargers (first charger 2a and second charger 2b) and multiple vehicles (first vehicle 3a and second vehicle 3b), and multiple second data sets (second data 12a and second data 12b) sent from the server device 1 to the multiple chargers and multiple vehicles, respectively. The multiple first data sets and the multiple second data sets can be exchanged with the server device 1 simultaneously.

[0058] Although Figure 1B shows multiple chargers, the battery management system of the present invention can also be used when multiple vehicles are charging a single charger.

[0059] The battery management system of the present invention may be used after passenger registration. When passenger registration, vehicle information can also be registered, allowing for prior knowledge of the vehicle information. The vehicle information includes initial value data, and the types of initial value data related to the battery pack 4 include internal resistance (R) value, SOC-OCV characteristic data, and FCC, etc. An example of when initial values ​​can be determined is during the aging process before shipment of the battery pack or vehicle.

[0060] Figure 2 shows a detailed configuration example of vehicle 3. Vehicle 3 has a power receiving connector 5, and charging is possible by plugging the power receiving connector 5 into the charger 2. In some cases, the charger 2 may also be equipped with a power receiving connector. The charger 2 is installed at home, a charging station, or a public parking lot, etc. Vehicle 3 is configured as a plug-in hybrid vehicle, EV vehicle, or industrial vehicle such as an electric forklift, capable of charging the battery pack 4 with power from the charger 2.

[0061] As shown in Figure 2, the battery pack 4 has a rechargeable battery (secondary battery) 41. The secondary battery 41 has a battery pack with multiple battery cells. When the carrier ions of the secondary battery 41 are lithium ions, the secondary battery is referred to as a lithium-ion secondary battery. Alternatively, a nickel-metal hydride battery may be used as the secondary battery 41. The battery pack 4 is sometimes referred to as a battery.

[0062] The secondary battery 41 is electrically connected to the power receiving connector 5 via at least a first switch SW11 and a second switch SW12. The first switch SW11 is electrically connected to the negative terminal of the secondary battery 41, and the second switch SW12 is electrically connected to the positive terminal of the secondary battery 41.

[0063] A power control unit 42 is electrically connected to the secondary battery 41, and a drive motor 43 is electrically connected to the power control unit 42. The power control unit 42 has the function of converting the DC power supplied from the secondary battery 41 into AC power and outputting it to the drive motor 43. The power control unit 42 has, for example, an inverter circuit capable of the above conversion.

[0064] Furthermore, the power control unit 42 may have a function to convert the AC power generated by the drive motor 43 into DC power and output the DC power to the secondary battery 41 when the vehicle 3 decelerates or stops. In other words, the secondary battery 41 may store the regenerative power generated by the drive motor 43.

[0065] The secondary battery 41 has a battery pack containing multiple battery cells 44(1) to 44(n) (where n is a natural number of 2 or more), and the multiple battery cells are connected in series with each other. In the battery pack, the cell balance state is determined during the charging period, and if cell balancing is not possible, a balancing process is performed. It is preferable that the balancing process is completed during the charging period using the state of charge estimation of each battery cell.

[0066] Estimating SOC-OCV characteristics is crucial during the balancing process. Preferably, the estimated SOC-OCV characteristics sent from server device 1 are in the form of a table. From this table, vehicle 3 can select the SOC-OCV characteristics that are optimal for its actual battery pack, create a table for vehicle 3, and complete the estimation of SOC-OCV characteristics. The creation of the table for vehicle 3 may also be achieved by selecting the optimal SOC-OCV characteristics (table) from multiple SOC-OCV characteristics (tables) sent from server device 1.

[0067] Furthermore, the server device 1 may transmit information on the health status of the battery cells (FCC / FCC0, where FCC0 is the initial full charge capacity) that has been stored to the vehicle 3. The accuracy of the table for vehicle 3 can be improved by using the health status of the battery cells.

[0068] The secondary battery 41 shown in Figure 2 has a balance circuit 45 electrically connected to it for balancing. There are two types of balance circuits 45: active and passive. An active balance circuit balances multiple battery cells connected in series by distributing their capacity. A passive balance circuit balances by consuming the capacity of some of the battery cells in the battery pack. In Figure 2, an example of a passive balance circuit 45 is shown, but an active balance circuit may also be used.

[0069] The balance circuit 45 has at least several resistors 46(1) to 46(n) (where n is a natural number of 2 or more) corresponding to several battery cells 44(1) to 44(n).

[0070] The balance circuit 45 also has at least several switches SW21(1) to SW21(n) (where n is a natural number of 2 or more) corresponding to several battery cells 44(1) to 44(n) and several resistors 46(1) to 46(n).

[0071] In the balance circuit 45, the group containing the resistor 46(1) and the switch SW21(1) is enclosed by a dotted line and designated as circuit 47(1). The balance circuit 45 has multiple circuits 47(1) to 47(n) (where n is a natural number of 2 or more) depending on the battery cell. The configuration of circuit 47 often differs between active and passive types, but the configuration containing a resistor and a switch is often common. That is, circuit 47 can be applied to either an active balance circuit or a passive balance circuit.

[0072] It is preferable that n be equal in the multiple battery cells and circuits described above, i.e., that the same number of cells are arranged. However, it is also possible to share a circuit among, for example, 2 to 15 battery cells. Sharing a circuit can reduce costs.

[0073] The balance circuit 45 has the function of aligning the State of Charge (SOC) of multiple battery cells 44(1) to 44(n). This function can also be described as a function that manages all battery cells to operate within the safe operating range. Here, we will explain the function of aligning the SOC or the importance of aligning the SOC using the four battery cells shown in Figure 3 (the first battery cell 44(1) to the fourth battery cell 44(4)).

[0074] As shown in Figure 3, the first battery cell 44(1) to the fourth battery cell 44(4) have different states of charge (SOC) at a given time. This is equivalent to the SOC-OCV characteristics shown in Figure 3 being different for each battery cell. This state means that the SOCs of the first battery cell 44(1) to the fourth battery cell 44(4) are scattered. Figure 3 shows the case where the SOCs are largest in the order of fourth battery cell 44(4) > first battery cell 44(1) > third battery cell 44(3) > second battery cell 44(2).

[0075] The first battery cell 44(1) to the fourth battery cell 44(4) are electrically connected to the first circuit 47(1) to the fourth circuit 47(4), respectively. To reiterate, the first battery cell 44(1) to the fourth battery cell 44(4) are those of the secondary battery 41 shown in Figure 2. The first circuit 47(1) to the fourth circuit 47(4) are those of the balance circuit 45 shown in Figure 2.

[0076] When charging the secondary battery 41 is started in the state of charge (SOC) shown in Figure 3, the fourth battery cell 44(4) completes charging the fastest. If charging of the secondary battery 41 continues while the fourth battery cell 44(4) is fully charged, the fourth battery cell 44(4) will become overcharged. On the other hand, if charging of the secondary battery 41 is stopped while the fourth battery cell 44(4) is fully charged, the battery cells other than the fourth battery cell 44(4) will not be fully charged, resulting in a decrease in the discharge capacity of the secondary battery 41.

[0077] Furthermore, when the secondary battery 41 is used in the state of charge (SOC) shown in Figure 3, the capacity of the second battery cell 44(2) will be depleted the fastest. If the secondary battery 41 continues to be used while the capacity of the second battery cell 44(2) is depleted, the second battery cell 44(2) will enter an over-discharge state. On the other hand, if the secondary battery 41 is stopped from being used while the capacity of the second battery cell 44(2) is depleted, capacity remains in the other battery cells, resulting in a decrease in the dischargeable capacity of the secondary battery 41.

[0078] To suppress such a decrease in discharge capacity, it is desirable to equalize the State of Charge (SOC) of each battery cell. This process of equalizing the SOC of each battery cell is referred to as balancing. Based on the situation shown in Figure 3, it may be determined that balancing is necessary during the charging period or other times in the battery pack 4.

[0079] To standardize the State of Charge (SOC) of each battery cell, it is necessary to accurately estimate the current SOC of each battery cell. Since it is difficult to measure the SOC of each battery cell, it is preferable to estimate it using measurable values ​​(current and voltage) for each battery cell with server device 1. When voltage is used as the measurable value, the SOC can be estimated using the SOC-OCV characteristic as shown in Figure 3. The measured voltage can be matched to the OCV in the SOC-OCV characteristic. The timing for performing SOC estimation using this OCV is preferably the initial and final stages of charging, which are circled with dotted lines in Figure 3. The initial and final stages of charging are periods in the SOC-OCV characteristic where the change in OCV is large but the change in SOC is small. This period is preferable as an estimation timing because the influence of OCV error in SOC estimation is small.

[0080] The timing for estimating the State of Charge (SOC) can be during the mid-charging phase, which lies between the initial and final stages of charging as shown in Figure 3. The mid-charging phase is a period in the SOC-OCV characteristics where changes in OCV significantly affect changes in SOC. During this period, it is advisable to use current integration (such as Coulomb counting) in the SOC-OCV characteristics. Current integration requires understanding the amount of current flowing through each battery cell. By measuring this current, obtaining the FCC of each battery cell, and combining it with methods such as Kalman filtering, it becomes possible to estimate the SOC.

[0081] When estimating SOC using current integration, the following calculation should be performed for the units of each battery cell.

[0082]

number

[0083] In the above formula, FCC is the Full Charge Capacity. When the State of Health (SOH) for each battery cell is sent from the server device 1, it is preferable to calculate the FCC by multiplying it by the initial value of the FCC held by the vehicle 3, which is FCC0. Note that SOH = FCC / FCC0.

[0084] On vehicle 3, machine learning is often performed to determine the optimal table for machine learning, or to estimate the internal resistance in each SOC.

[0085] The internal resistance of each SOC can be estimated, for example, from the current and voltage measured in the battery cell of vehicle 3. The internal resistance may be estimated by dividing it into a fast-responding resistance component and a slow-responding resistance component, as explained in the internal resistance estimation method of Embodiment 2. The fast-responding resistance component is thought to be related to electron transfer resistance, and the slow-responding resistance component is thought to be related to ion diffusion resistance within the active material solid. Battery cells degrade due to repeated charging and discharging, but the state of degradation differs depending on the type of battery cell and the installation environment, so the fast-responding resistance component and the slow-responding resistance component may change in different ways. Therefore, estimating the fast-responding resistance component and the slow-responding resistance component separately as described above can be said to be one way to indirectly know the state of degradation inside the battery. Thus, when using data on internal resistance for estimation of SOC-OCV characteristics, SOC estimation, and FCC estimation, it is preferable because the accuracy of various estimations improves as more information reflecting the internal state of the battery is provided. When estimating internal resistance in vehicle 3, it is preferable to include the estimated data as sequential data transmitted to the server device 1. The estimated data regarding internal resistance is particularly useful in estimating FCC in the server device 1 because it reflects the degradation state of each battery. Here, the server device 1 can store the estimated data for multiple vehicles 3.

[0086] In one embodiment of the present invention, SOC estimation can be performed based on OCV when performed at the beginning and end of charging, and using current integration when performed in the middle of charging. Since it is desirable to perform SOC estimation at an early stage for balancing processing of each battery cell, it is preferable to perform SOC estimation at the beginning or middle of charging. It is preferable that a server device performs SOC estimation, but it may also be performed by a vehicle control unit or the like.

[0087] Incidentally, SOC-OCV characteristics change over time due to degradation caused by repeated charging and discharging. Therefore, obtaining the current, or latest, SOC-OCV characteristics with high accuracy requires estimation based on a large amount of data, which can be time-consuming.

[0088] Because degradation occurs unevenly, the SOC-OCV characteristics of each battery cell vary. Other variations include variations in degradation rate, impedance, and self-discharge rate. For example, variations in degradation rate can be due to temperature dependence (degradation progresses more rapidly at higher temperatures), voltage dependence (degradation progresses more rapidly at higher charging voltages), or discharge depth dependence (degradation progresses more rapidly at deeper discharge depths). These factors are intricately intertwined, making it difficult to estimate the SOC of each battery cell. Furthermore, considering the above dependencies, estimating the SOC requires enormous calculations.

[0089] Therefore, in one aspect of the present invention, it is preferable to have the server device 1 perform calculation processing related to the estimation of the latest SOC-OCV characteristics.

[0090] For example, in Figure 3, after vehicle 3 has acquired the latest SOC-OCV characteristics, in order to match the SOC of the other battery cells to the SOC of the second battery cell 44(2), the switches in the first circuit 47(1), the third circuit 47(3), and the fourth circuit 47(4), which correspond to the battery cells other than the second circuit 47(2), are turned on. Then, discharge occurs in the battery cells other than the second battery cell 44(2), and the SOC of the battery cells other than the second battery cell 44(2) can be matched to the SOC of the second battery cell 44(2). Discharge using the resistors of circuit 47 is referred to as resistive discharge.

[0091] When aligning the State of Control (SOC) in this way, it can typically be achieved with a simple balance circuit 45 consisting of switches and resistors, but this wastes energy. Furthermore, heat is generated due to the energy consumption. When energy consumption is involved, it is referred to as a passive balance circuit or passive balancing process.

[0092] It is also possible to equalize the State of Charge (SOC) using other methods. For example, in Figure 3, to equalize the SOC of the other battery cells with that of the fourth battery cell 44(4), the switches of the first circuits 47(1) to the third circuits 47(3) corresponding to the battery cells other than the fourth battery cell 44(4) should be turned off, the switch (not shown) between the negative terminal of battery cell 44(3) and the positive terminal of battery cell 44(4) should be turned off, and the switch of the fourth circuit 47(4) connected to the negative terminal of battery cell 44(3) should be turned on to start charging. This allows the charging to bypass the fourth battery cell 44(4), increasing the SOC of the battery cells other than the fourth battery cell 44(4) and equalizing it with the SOC of the fourth battery cell 44(4).

[0093] This method requires bypassing the fourth battery cell 44(4) for charging. Therefore, compared to the case where the charging is aligned with the second battery cell 44(2), the circuit configuration becomes more complex, with an increased number of switches in the secondary battery 41 and the balance circuit 45. Furthermore, heat is generated due to energy consumption. In other words, it is equivalent to a passive balance circuit or balancing process.

[0094] When operating the balance circuit 45 in this manner, the current SOC value of each battery cell is used as the basis, so it is preferable to have the server device 1 estimate the SOC to obtain a highly accurate SOC. Furthermore, when operating the balance circuit 45, it is preferable to start the SOC estimation by the server device 1 at an early stage of the charging period.

[0095] Just as there is a demand to shorten the charging time, such as through rapid charging modes, it is also desirable to complete the balancing process in a short amount of time. In this respect as well, it is preferable to start the SOC estimation on server device 1 at an early stage of the charging period.

[0096] AI can be used via an algorithm for estimation in server device 1.

[0097] AI can be used via an algorithm for estimation in vehicle 3.

[0098] One aspect of the present invention involves a new balancing process in which the battery pack 4 acquires data relating to the internal state of the battery cells 44 at regular intervals, transmits this data from the battery pack 4 to the server device 1 using a communication network 7 or the like, and then has the server device 1 perform an estimation process relating to the internal state, creating and saving multiple execution results. The battery pack 4 then selects the internal state that is closest to the current state of the battery cells 44, the so-called latest internal state, from the data stored in the server device 1 or the storage unit 52. Communication between the battery pack 4 and the server device 1 can be performed via the vehicle control unit 50, but the battery pack 4 may also be configured to have a communication function.

[0099] According to this embodiment of the present invention, data related to SOC and the like can be obtained with high accuracy and in a short time. The calculation process related to SOC estimation performed on the server device 1 can be completed in a short time, and the frequency of calculations on the server device 1 can also be increased. Furthermore, since the calculation process on the server device 1 can be performed in parallel while the vehicle 3 is charging, the balancing process can be completed in a short time.

[0100] Furthermore, the data and estimation results regarding SOC stored in server device 1 are versatile and can be provided to multiple battery packs 4. With this system, battery pack 4 can acquire SOC and other estimated values ​​with high accuracy, eliminating the need for new control units in battery pack 4 and enabling the most efficient matching of SOCs. Unnecessary energy consumption associated with balancing processing is suppressed, allowing battery pack 4 to perform at its maximum capacity.

[0101] To achieve the above, data is transmitted and received between the vehicle 3 and the server device 1, as shown in Figures 1A and 1B. It is preferable that the data is transmitted and received when the vehicle 3 is stopped and connected to the charger 2. When connected to the charger 2, the battery pack 4 of the vehicle 3 starts charging. The charging period while the power receiving connector 5 is connected to the charger 2 can be divided into an initial and mid-term CC (Constant Current) charging period and a final CV (Constant Voltage) charging period.

[0102] While the power receiving connector 5 is connected to the charger 2, communication is possible between the server device 1 and the vehicle 3. During the initial and middle stages of charging, i.e., the period corresponding to CC charging, communication can be used to determine the optimal SOC-OCV characteristics in the vehicle 3.

[0103] At the end of the charging period, i.e., during the CV charging period, the remaining capacity until full charge can be calculated from each battery cell, and the battery cell that takes the longest time to reach full charge can be identified. For the other battery cells, the timing of when to start discharging in circuit 47, the so-called order of discharge in circuit 47, can be determined.

[0104] During the CC charging period, the SOC-OCV characteristics table is created on server device 1, but after charging is complete, the table can be modified by the GPU installed in the vehicle if necessary.

[0105] Vehicle 3 may integrate the SOC data from each battery cell 44 to create a remaining charge indicator table for the passenger (user).

[0106] The transmission and reception of the first data 11 and the second data 12 are made possible by the vehicle control unit 50 shown in Figure 2. The vehicle control unit 50 has at least a CPU 51, a memory unit 52, and a communication unit 53, and operates on power supplied from a secondary battery 41 or a separately provided storage battery.

[0107] The vehicle control unit 50 is sometimes called a vehicle control unit. The vehicle control unit 50 is a control device that determines the state of the vehicle and maintains an optimal state, and can control the entire vehicle using CAN (Controller Area Network) communication, CAN FD (CAN with Flexible Data rate), in-vehicle Ethernet (registered trademark), etc.

[0108] The vehicle control unit 50 can select data related to the SOC, etc., stored in the server device 1. For example, the vehicle control unit 50 has at least a CPU 51, and the CPU 51 can perform calculations to select the optimal data related to the SOC, etc., that is closest to the current state of the battery cell from the data stored in the server device 1 or the storage unit 52. In addition to the CPU 51, the vehicle control unit 50 may have a CPU and a GPU capable of performing calculations.

[0109] The vehicle control unit 50 has a storage unit 52, which includes RAM and ROM. The storage unit 52 can record SOC-OCV characteristic data of multiple battery cells 44. The storage unit 52 can also record data related to the SOC selected from the server device 1. The storage unit 52 can also record programs for controlling the battery pack 4. By executing one of these programs, the CPU 51 can select the data related to the SOC that is closest to the current state for each of the multiple battery cells 44 from the data stored in the server device 1 or the storage unit 52.

[0110] The vehicle control unit 50 has a communication unit 53 and is capable of sending and receiving data with the server device 1.

[0111] The battery pack 4 has a protection circuit 60. The current monitoring circuit 61 of the protection circuit 60 may have a sensor function that measures the charge and discharge current as a measured value obtained from the secondary battery 41. By measuring the charge and discharge current using the current monitoring circuit 61, the coulomb count of the battery cells can be performed, and data related to the State of Charge (SOC) can be obtained.

[0112] The voltage monitoring circuit 62 of the protection circuit 60 may have a sensor function that can measure the terminal voltage of each battery cell 44 as a measured value obtained from the secondary battery 41, etc. The temperature monitoring circuit 63 of the protection circuit 60 may have a sensor function that can measure the temperature of each battery cell 44 as a measured value obtained from the secondary battery 41, etc. The path interruption circuit 64 of the protection circuit 60 can interrupt the charge and discharge current path to the secondary battery 41, etc.

[0113] The vehicle control unit 50 can acquire measured values ​​obtained from the protection circuit 60 as parameters. Based on the obtained measured values, it can forcibly stop the discharge or charging of battery cells that are determined to be in an over-discharged or over-charged state. The vehicle control unit 50 can decide whether or not to forcibly stop the process.

[0114] The vehicle control unit 50 can control the balance circuit 45 according to selected data such as SOC. Specifically, the vehicle control unit 50 can control the on or off of the switches SW21(1) to SW21(n) of the balance circuit 45.

[0115] A start switch 71 is electrically connected to the vehicle control unit 50. The vehicle control unit 50 can switch the vehicle 3 between running and stopped states in response to the operation of the start switch 71 by a passenger. The vehicle control unit 50 can also switch the vehicle 3 between running and stopped states in response to the charge state of the secondary battery 41, enabling the operation of the start switch 71.

[0116] In this embodiment, data relating to the State of Charge (SOC) of each battery cell is acquired from the battery pack 4 as sequential data at regular intervals, and the acquired data is stored in the server device 1 using a communication network 7, etc. Furthermore, the server device 1 can perform calculations related to SOC estimation to calculate the estimation result. The battery pack 4 only needs to select the data relating to the SOC that is closest to the current state of the battery cell 44 from the data stored in the server device 1 or the storage unit 52, so that data relating to the SOC can be obtained with high accuracy and in a short time.

[0117] The data and estimation results regarding SOC etc. stored on the server device are versatile and can therefore be provided to battery packs 4 owned by multiple vehicles 3.

[0118] With such a system, the battery pack 4 can obtain highly accurate estimated SOC and other parameters, and the balancing circuit and other components can be used to process the SOC most efficiently. The battery pack 4, after the balancing process has been performed, is configured to utilize the optimal FCC. Such a configuration allows for maximum utilization of the battery, and is sometimes referred to as limit utilization of the battery. By using a battery management system according to one aspect of the present invention, the multiple battery cells 44 in the battery pack 4 can be utilized to their limits.

[0119] This embodiment can be implemented in appropriate combination with other embodiments.

[0120] (Embodiment 2) This embodiment describes the processing method for SOC-OCV characteristic data.

[0121] [Processing method for SOC-OCV characteristic data] Figure 4 illustrates the creation of SOC-OCV characteristic data in the server device 1 and the selection of SOC-OCV characteristic data on the vehicle 3 side, for example, in the vehicle control unit 50, with respect to the SOC-OCV characteristic data contained in the first data 11 and the second data 12.

[0122] Server device 1 has a first algorithm 121. The first algorithm 121 has the function of creating first SOC-OCV characteristic data 162 using at least a portion of the first data 11 as input data. The first SOC-OCV characteristic data 162 has estimated values. Preferably, the first algorithm 121 has a first neural network 131. The server device 1 also has the function of transmitting the first SOC-OCV characteristic data 162 to vehicle 3 as part of the second data 12. The transmitted first SOC-OCV characteristic data 162 is added as part of the vehicle 3's SOC-OCV characteristic data list 161.

[0123] Vehicle 3 has a second algorithm 122. The second algorithm 122 is preferably stored in the storage unit 52 of the vehicle control unit 50. The second algorithm 122 has the function of selecting a second SOC-OCV characteristic data 163 from multiple SOC-OCV characteristic data lists 161, using the SOC-OCV characteristic data list 161 and the voltage value, current value, battery cell temperature, and capacity value related to the battery pack 4, which are aggregated in the vehicle control unit 50, as input values. The second SOC-OCV characteristic data 163 selected is the one that is closest to the state of the battery cell 44 of vehicle 3 at the time of selection. Closest means the one with the smallest difference from the entire range of the battery cell's SOC-OCV characteristics. Since it is difficult to actually measure the entire range of the battery cell's SOC-OCV characteristics, the second algorithm 122 needs to select the second SOC-OCV characteristic data 163 based on limited input data. Therefore, it is preferable that the second algorithm 122 includes a second neural network 132. By including the second neural network 132, the second algorithm 122 can select the second SOC-OCV characteristic data 163 that is closest to the state of the battery cell using limited input data. The vehicle 3 also has a function to transmit the second SOC-OCV characteristic data 163 as part of the first data 11 to the server device 1. The second algorithm 122 may also be installed on an electronic device such as a smartphone owned by the passenger of the vehicle 3.

[0124] For example, one of the following can be used as the first neural network 131: FFNN (Feedforward Neural Network), CNN (Convolutional Neural Network), RNN (Recurrent Neural Network), and LSTM (Long Short-Term Memory).

[0125] For example, one of FFNN, CNN, RNN, and LSTM can be used as the second neural network 132. Alternatively, the second neural network 132 may use a decision tree to select the second SOC-OCV characteristic data 163 from the SOC-OCV characteristic data list 161 as a classification problem.

[0126] Next, the data description method for the first SOC-OCV characteristic data 162 will be explained using Figure 5. As a battery management system according to one aspect of the present invention, for example, a data description method can be used in which SOC data and OCV data for obtaining the first SOC-OCV characteristic data 162 are assigned to specific bits, as shown in Figure 5. Figure 5 shows the description method for SOC data, showing the relationship between bit data and corresponding SOC [%]. It also shows the relationship between bit data and corresponding voltage [V] as an OCV data description method. When the specific bit data in the SOC data is, for example, 0011, the corresponding SOC is 40%, and the corresponding voltage in the OCV data is 3.300V. Under normal use conditions of a battery cell, the SOC is used to be in the range of 0% to 100%, but if the battery cell is not used for a long period of time, it may be in an over-discharged state of 0% or less. In addition, during charging, overcharging, where the battery is charged to 100% or more, needs to be addressed as a potential risk. Therefore, as shown in Figure 5, it is desirable that the SOC data also support SOC ranges smaller than 0% and SOC ranges larger than 100%. Furthermore, OCV data is paired with SOC data and is assigned as OCV data to correspond to each SOC data.

[0127] Furthermore, Figure 5 shows an example of a data description method for the first SOC-OCV characteristic data 162, where the data intervals are finer in the range where the SOC is close to 100%. In a battery cell, an overcharge state where the SOC exceeds 100% can lead to a decrease in the safety of the battery cell and a decrease in battery life, so it is desirable to allocate more bit data in the SOC range where the SOC is close to 100%. Bit data allocation can be performed by the server device 1. The SOC range where the SOC is close to 100% is preferably 90% to 110%, more preferably 95% to 105%, and it is desirable to allocate more than twice as much bit data in this range compared to other ranges.

[0128] Furthermore, while Figure 5 shows a large allocation of bit data in the SOC range close to 100%, it would be beneficial to allocate data in the SOC range closer to 0% as well, so that the data intervals become finer. Allocating a large amount of bit data in the SOC range close to 0% makes it easier to prevent sudden shutdowns in vehicle 3, which has battery cells, and thus improves safety.

[0129] As shown in Figure 5, increasing the bit data allocation for a portion of the SOC makes it possible to form sufficient SOC-OCV characteristic data even with a small number of bits, enabling lighter data communication between the server device 1 and the vehicle 3, as well as lighter data within the vehicle 3.

[0130] Figure 5 shows an example using 4 bits for illustrative purposes, but the data can be described using a larger number of bits, such as 8 bits, 16 bits, 32 bits, or 64 bits. When using a larger number of bits, it may not be necessary to allocate a large amount of bit data to a specific range of the SOC as described above. This is because, when a large number of bits are allocated to the SOC-OCV characteristic data, it is possible to describe the entire range of the SOC in detail, rather than just a specific range.

[0131] Furthermore, Figure 5 shows an example of a data description method for the first SOC-OCV characteristic data 162, in which, in addition to the allocation of SOC data and OCV data, State A to State D, which represent the state of the battery cell, are allocated to the surplus bit data. State A to State D, which represent the state of the battery cell, can be allocated, for example, as data indicating a dangerous condition such as an internal short circuit.

[0132] As described above, the data processing function for SOC-OCV characteristic data provided by the battery management system according to one aspect of the present invention makes it possible to improve the accuracy of battery cell estimation. Furthermore, the reduction in data size (reduction of data volume) and optimization for neural network processing of SOC-OCV characteristic data performed by the server device 1 make it possible to reduce the power consumption of the control unit of the vehicle 3.

[0133] [FCC, processing function related to internal resistance] Figure 6 shows an example where the server device 1 estimates the FCC (Frequency Critical Value) of the first data 11 and the internal resistance (R) of the second data, and the vehicle 3 estimates the internal resistance. In this way, estimation may be performed on the vehicle 3 side in addition to the server device 1. Using Figure 6, the functional configuration of the battery management system regarding the estimation of FCC and internal resistance will be explained.

[0134] Server device 1 has a third algorithm 123. The third algorithm 123 calculates the internal resistance 171a (R data from one cycle prior estimated by the battery cell) based on the battery cell. n-1 The system has the function of estimating the FCC172 using the input data (as indicated by ). Preferably, the third algorithm 123 has a third neural network 133. The server device 1 also has the function of transmitting the FCC172 to the vehicle 3 as part of the second data 12.

[0135] Vehicle 3 has a fourth algorithm 124. The fourth algorithm 124 takes FCC 172, second SOC-OCV characteristic data 163, and the voltage, current, and capacity values ​​of the battery cell as input data and calculates the internal resistance 171b of the battery cell (R data estimated from the battery cell, where R is R). n It has the function of estimating (referred to as ). The fourth algorithm 124 preferably has a fourth neural network 134. Also, the vehicle 3 has an internal resistance 171b (R n It has the function of transmitting ) as part of the first data 11 to the server device 1.

[0136] For example, one of FFNN, CNN, RNN, and LSTM can be used as the third neural network 133.

[0137] For example, one of the following can be used as the fourth neural network 134: FFNN, CNN, RNN (and LSTM).

[0138] Next, the method for estimating the internal resistance 171 (denoted as R) will be explained using Figure 7. Figure 7 shows the function of the fourth algorithm 124 of the vehicle 3. By inputting the first SOC-OCV characteristic data 162, FCC 172, and the internal measurement values ​​of the battery cell 44 into the fourth algorithm 124, the internal resistance 171 is estimated. The internal resistance may also be estimated by the server device 1.

[0139] The first SOC-OCV characteristic data 162 should preferably be in the data format described in Figure 5. The internal measured values ​​of each battery cell can be determined based on the voltage (V) 31, current (I) 32, and capacity (Q) 33 and temperature (T) 34 measured by a Coulomb counter or the like.

[0140] As described above, the functions for estimating FCC and internal resistance of the battery management system according to one aspect of the present invention make it possible to improve the accuracy of estimating the FCC and internal resistance of battery cells. Furthermore, by using lightweight (reduced data volume) SOC-OCV characteristic data for estimating internal resistance, it becomes suitable for neural network processing, and it becomes possible to reduce the power consumption of the control unit of the vehicle 3.

[0141] [Method for measuring internal resistance] Instead of the method for estimating the internal resistance 171 shown in Figure 7, the internal resistance 171 may be estimated from the measurement results using the current pause method described in Figures 8 and 9. In this case, the fourth algorithm 124 should have a function for estimating the internal resistance using the current pause method described below.

[0142] The current pause method is a method for estimating the internal resistance of a battery cell by setting a pause period during CC charging in which no charging is performed, and analyzing the change in voltage of the battery cell during this pause period. Alternatively, it is a method for estimating the internal resistance of a battery cell by setting a pause period during CC discharge in which no discharge is performed, and analyzing the change in voltage of the battery cell during this pause period. The pause period is preferably 1 second to 10 minutes, more preferably 5 seconds to 5 minutes, and even more preferably 10 seconds to 3 minutes.

[0143] Figure 8 illustrates the analysis method of the current pause method. Figure 8 shows an example of the current pause method in CC discharge, but it is not limited to this and can also be used in CC charging. Let ΔV(0.1s) be the difference between the battery voltage immediately before the pause period and the battery voltage 0.1 seconds after the start of the pause period. Also, let ΔV(0.1s~120s) be the difference between the battery voltage 0.1 seconds after the start of the pause period and the battery voltage 120 seconds after the start of the pause period (the battery voltage at the end of the pause period). Next, let R(0.1s) be the fast-responding resistance component obtained by dividing ΔV(0.1s) by the current value of constant-current discharge, and let R(0.1s~120s) be the slow-responding resistance component obtained by dividing ΔV(0.1s~120s) by the current value of constant-current discharge. The fast-responding resistance component R(0.1s) is thought to originate mainly from electrical resistance (electron conduction resistance), while the slow-responding resistance component R(0.1s~120s) is thought to originate mainly from Li diffusion resistance within the active material particles.

[0144] Next, examples of analysis results using the current pause method are shown below. For battery samples using different positive electrode active materials (Sample 1 and Sample 2), Figure 9A shows the transition of the fast-responding resistance component R(0.1s) and the slow-responding resistance component R(0.1s~120s) as an example of analysis using the analysis method described in Figure 8. Figure 9B shows the transition of the fast-responding resistance component R(0.1s) and the slow-responding resistance component R(0.1s~120s) for Sample 1.

[0145] As shown in Figure 9A, the fast-responding resistance component R(0.1s) of sample 1 tends to decrease and then increase, while the fast-responding resistance component R(0.1s) of sample 2 changes only in the increasing direction. Thus, the change in the fast-responding resistance component R(0.1s) does not follow a uniform trend and may differ depending on the battery.

[0146] As shown in Figure 9B, the slow-responding resistance component R(0.1s~120s) changes more significantly than the fast-responding resistance component R(0.1s). The slow-responding resistance component R(0.1s~120s) increases sharply from around cycle 20 and remains almost constant from cycle 27 onwards. Thus, the fast-responding resistance component R(0.1s) and the slow-responding resistance component R(0.1s~120s) can have different trends in change.

[0147] Therefore, it is preferable that the fourth algorithm 124 has a function to predict the future changes in internal resistance for each resistance component, using a neural network such as an LSTM as time-series data estimation for both the fast-responding resistance component R(0.1s) and the slow-responding resistance component R(0.1s~120s).

[0148] The above-mentioned prediction function may be provided by the server device 1. It is preferable that the server device 1 has a function to predict future changes in internal resistance for each resistance component, using a neural network such as an LSTM as time-series data estimation for each of the fast-responding resistance component R(0.1s) and the slow-responding resistance component R(0.1s~120s). This is because it is possible to collect data corresponding to the secondary batteries 41 of multiple vehicles 3 and improve the prediction accuracy of the neural network.

[0149] As shown in the example of vehicle 3, when there are multiple battery cells 44, it is preferable to measure, estimate, and predict the internal resistance of each battery cell. Multiple battery cells 44 have variations in their manufacturing characteristics, and the ambient temperature may also change depending on the mounting position of the battery cells 44 in the secondary battery 41. Therefore, by measuring, estimating, and predicting the internal resistance of each of the multiple battery cells 44, it is possible to create a battery control system that can be controlled more accurately.

[0150] Furthermore, in order to accurately analyze the fast-responding resistance component R(0.1s) and the slow-responding resistance component R(0.1s~120s) when estimating the internal resistance, the synchronization of the measured voltage (V) 31 and current (I) 32 values ​​measured from the battery cell 44 is important. For this reason, in the current monitoring circuit 61 and the voltage monitoring circuit 62, it is preferable to provide an A / D conversion unit for each of the voltage (V) 31 and current (I) 32 values ​​of the multiple battery cells 44, rather than using a scanning-type A / D conversion unit. In this case, the voltage (V) 31 of the multiple battery cells 44 may be acquired using a change in the current (I) 32 as a trigger.

[0151] Vehicle 3 may also have a third SOC-OCV characteristic data set, in addition to the SOC-OCV characteristic data list 161 and the second SOC-OCV characteristic data set 163. The third SOC-OCV characteristic data set can be created based on the second SOC-OCV characteristic data set 163 and the estimated load of vehicle 3. The average current consumption value of the battery cells can be used as the estimated load. Compared with the second SOC-OCV characteristic data set 163, the third SOC-OCV characteristic data set has the corresponding voltage in the low SOC range set higher in the OCV data, according to the estimated load of vehicle 3. As a simplified example, for example, if SOC = 10% in the second SOC-OCV characteristic data set 163, the data will be recorded as SOC = 0% in the third SOC-OCV characteristic data set. In this example, the OCV for which SOC is 0% in the third SOC-OCV characteristic data set will be higher than the OCV for which SOC is 0% in the second SOC-OCV characteristic data set 163. It is also possible to display the third SOC-OCV characteristic data to the occupants of vehicle 3, which is preferable because it can prevent unexpected shutdowns of vehicle 3.

[0152] This embodiment can be implemented in appropriate combination with other embodiments.

[0153] (Embodiment 3) This embodiment describes the positive electrode used in the battery cell of the present invention.

[0154] [Positive electrode] Figure 10A shows an example of a cross-sectional view of a positive electrode. The positive electrode has a positive electrode active material layer 571 on a positive electrode current collector 550. The positive electrode active material layer 571 includes positive electrode active material 561, positive electrode active material 562, binder 555, conductive additive 553, conductive additive 554, and electrolyte 556. The positive electrode active material 561 refers to material whose average particle size is larger than that of the positive electrode active material 562.

[0155] [Cathode active material] The positive electrode active material 561 and / or positive electrode active material 562 are sometimes called positive electrode active material particles, but they can take on various shapes other than particulate. The positive electrode active material 561 and / or positive electrode active material 562 may be primary particles having multiple crystallites, or secondary particles formed by the aggregation of primary particles.

[0156] The positive electrode active material 561 and / or positive electrode active material 562 can be made of a material that allows for the insertion and removal of carrier ions. The carrier ions can be lithium ions, sodium ions, potassium ions, calcium ions, strontium ions, barium ions, beryllium ions, or magnesium ions.

[0157] Lithium composite oxides having olivine-type crystal structures, layered rock salt-type crystal structures, or spinel-type crystal structures are examples of materials capable of inserting and removing lithium ions. For example, a lithium composite oxide having an olivine-type crystal structure is denoted as LiMPO4 (where M = one of Fe, Mn, Ni, or Co). Fe and Mn are expected to be next-generation cathode materials due to their excellent thermal stability. For example, a lithium composite oxide having a layered rock salt-type crystal structure is denoted as LiMO2 (where M = one of Fe, Mn, Ni, or Co). When M is Co, LiMO2 is denoted as LiCoO2, which is sometimes written as LCO, and is also sometimes called lithium cobalt oxide. In a lithium composite oxide having a layered rock salt-type crystal structure, M may be one or more selected from Fe, Mn, Ni, and Co.

[0158] As a composite oxide having Ni, Mn, and Co, LiNi x Co y Mn zThere is a NiCoMn system (also referred to as NCM) represented by O2(x>0, y>0, 0.8<x + y + z<1.2). Specifically, for example, it is preferable to satisfy 0.1x<y<8x and 0.1x<z<8x. As an example, x, y, and z preferably satisfy x:y:z = 1:1:1 or values in the vicinity thereof. Or as an example, x, y, and z preferably satisfy x:y:z = 5:2:3 or values in the vicinity thereof. Or as an example, x, y, and z preferably satisfy x:y:z = 8:1:1 or values in the vicinity thereof. Or as an example, x, y, and z preferably satisfy x:y:z = 9:0.5:0.5 or values in the vicinity thereof. Or as an example, x, y, and z preferably satisfy x:y:z = 6:2:2 or values in the vicinity thereof. Or as an example, x, y, and z preferably satisfy x:y:z = 1:4:1 or values in the vicinity thereof.

[0159] In addition, in the NiCoMn system shown above, it is preferable to contain any one or more selected from aluminum, magnesium, titanium, and boron in an amount of 0.1 mol% or more and 3 mol% or less.

[0160] In addition to this, oxides such as V2O5 and Nb2O5 are being studied as cathode materials. For example, spinel-type crystal structure lithium composite oxides include lithium manganese spinel (LiMn2O4) and the like.

[0161] The lithium composite oxide may contain at least one or more elements selected from the group consisting of nickel, chromium, aluminum, iron, magnesium, molybdenum, zinc, zirconium, indium, gallium, copper, titanium, niobium, silicon, fluorine, and phosphorus. A lithium composite oxide containing aluminum and having Ni, Mn, and Co may be denoted as NCMA. A lithium composite oxide containing aluminum and having Ni and Co may be denoted as NCA.

[0162] The average particle size of the positive electrode active material 561 is 1 μm or more and 50 μm or less, preferably 5 μm or more and 20 μm or less. In the case of ternary composite oxides such as NCM, the positive electrode active material 561 can be considered as secondary particles, and it is preferable that the average particle size of the secondary particles be 1 μm or more and 50 μm or less, preferably 5 μm or more and 20 μm or less.

[0163] To increase the packing density of the active material, a positive electrode active material 562 with a different particle size may be added. A difference in particle size means a difference in the maximum value of the average particle size. For example, the positive electrode active material 562 has a smaller maximum value of average particle size than the positive electrode active material 561. Preferably, the maximum value of the average particle size of the positive electrode active material 562 is between 1 / 6 and 1 / 10 of the maximum value of the average particle size of the positive electrode active material 561. By mixing active materials with different particle sizes, the packing density of the active material in the positive electrode active material layer 571 can be improved.

[0164] The charge density can be increased even without the positive electrode active material 562. If the positive electrode active material 562 is omitted, the manufacturing process can be reduced, further lowering costs.

[0165] The positive electrode active material 561 and / or positive electrode active material 562 may have grain boundaries. The grain boundaries may be located between crystallites.

[0166] The positive electrode active material 561 and / or positive electrode active material 562 may have additive elements in their surface layer. Figure 10A shows the surface layer 572 of the positive electrode active material 561. In a cross-sectional view, the surface layer 572 is located within 50 nm, more preferably within 35 nm, even more preferably within 20 nm, and most preferably within 10 nm from the surface of the positive electrode active material 561 toward the interior.

[0167] It is desirable for the added elements to be unevenly distributed in the surface layer. Uneven distribution refers to a state where the added elements are distributed non-uniformly or unevenly, resulting in higher concentrations of the added elements in some areas compared to others. Uneven distribution can also be described as segregation or precipitation.

[0168] Depending on their type, some additive elements do not contribute to the capacity of the positive electrode active material. It is preferable that such additive elements are unevenly distributed on the surface of the positive electrode active material. This uneven distribution can be confirmed by the fact that the additive elements are present at a higher concentration on the surface than in the interior of the positive electrode active material. The presence of additive elements at least on the surface prevents structural degradation during charging and discharging, resulting in a positive electrode active material that is less prone to degradation.

[0169] A structure in which a surface layer 572 is provided within the active material is sometimes referred to as a core-shell structure. The core-shell structure can also be applied to the positive electrode active material 562.

[0170] [Binder] The binder 555 is provided to prevent the positive electrode active material 561 or the conductive additive 553 from sliding off the positive electrode current collector 550. The binder 555 also plays a role in binding the positive electrode active material 561 and the conductive additive 553 together. Therefore, the binder 555 may be positioned in contact with the positive electrode current collector 550, between the positive electrode active material 561 and the conductive additive 553, or intertwined with the conductive additive 553.

[0171] Binder 555 contains a polymer material, specifically a resin. Adding too much binder can reduce the proportion of positive electrode active material 561 in the positive electrode active material layer 571. Since a decrease in the proportion of positive electrode active material 561 leads to a reduction in the discharge capacity of the secondary battery, the amount of binder 555 added should be kept to a minimum.

[0172] [Conductive additive] The positive electrode active material 561 is a composite oxide and therefore may have high resistance. This makes it difficult to collect current from the positive electrode active material 561 to the positive electrode current collector 550. Therefore, conductive additives 553 and / or 554 play a function of assisting the current path between the positive electrode active material 561 and the positive electrode current collector 550, the current path between multiple positive electrode active materials 561, and the current path between multiple positive electrode active materials and the positive electrode current collector 550. In order to perform these functions, conductive additives 553 and / or 554 are made of a material with lower resistance than the positive electrode active material 561, and some conductive additives 553 and / or 554 are positioned in contact with the positive electrode current collector 550, while others are positioned in the gaps of the positive electrode active material 561.

[0173] Conductive additive 553, also called a conductivity imparting agent or conductive material due to its role, is made of carbon or metallic materials. Carbon black (furnace black, acetylene black, graphite, etc.) is one example of a carbon material used in conductive additive 553. Carbon black has a smaller particle size than the positive electrode active material 561. Carbon nanotubes (CNTs) and VGCF (registered trademark) are examples of fibrous carbon materials used in conductive additive 554. Multilayer graphene is an example of a sheet-like carbon material used in conductive additive 554. Figure 10A shows a cross-section of the positive electrode, where the sheet-like carbon material may appear thread-like.

[0174] The particulate conductive additive 553 can penetrate the gaps in the positive electrode active material 561 and is also prone to aggregation. Therefore, the particulate conductive additive 553 can assist in the conductive paths between nearby positive electrode active materials (between adjacent positive electrode active materials). The fibrous or sheet-like conductive additive 554 has bent regions but is larger than the positive electrode active material 561. Therefore, the fibrous or sheet-like conductive additive 554 can assist in the conductive paths not only between adjacent positive electrode active materials but also between positive electrode active materials that are spaced apart. It is preferable to mix the conductive additives in particulate, fibrous, and sheet forms.

[0175] When graphene is used as a sheet-like conductive additive and mixed with carbon black as a particulate conductive additive, it is preferable that the weight of the carbon black in the slurry be 1.5 to 20 times, preferably 2 to 9.5 times, that of the graphene.

[0176] Furthermore, when the mixing ratio of graphene and carbon black is within the above range, the carbon black does not aggregate and disperses easily. Also, when the mixing ratio of graphene and carbon black is within the above range, the electrode density can be increased compared to when only carbon black is used as a conductive additive. By increasing the electrode density, the volume per unit weight can be increased. Specifically, the density of the positive electrode active material layer can be increased to more than 3.5 g / cc.

[0177] Furthermore, a positive electrode using a mixture of graphene and carbon black as a conductive additive can handle faster charging than a positive electrode using only graphene as a conductive additive. It is also preferable to use a mixing ratio of graphene and carbon black within the above range.

[0178] One type of rechargeable battery used in vehicles is the laminated rechargeable battery. To increase capacity, the number of laminated rechargeable batteries is increased to extend the vehicle's driving range. However, this increases the vehicle's weight, thus increasing the energy required to move the vehicle. It is possible to extend the driving range without increasing the number of laminated rechargeable batteries, while keeping the total weight of the vehicle almost unchanged.

[0179] Furthermore, as the secondary batteries installed in vehicles become higher capacity, more power is required for charging, so it is desirable to complete the charging process in a short time. Also, when the secondary batteries installed in vehicles become higher capacity, rapid charging becomes possible in so-called regenerative charging, where power is temporarily generated when the vehicle brakes are applied and that power is used to recharge the battery, which is desirable.

[0180] [Electrolyte] Electrolyte 556 preferably comprises a solvent and a salt of a metal that acts as a carrier ion. As the solvent for the electrolyte, an aprotic organic solvent is preferred, such as one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, chloroethylene carbonate, vinylene carbonate, γ-butyrolactone, γ-valerolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfoxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran, sulfolane, sultone, etc., or two or more of these can be used in any combination and ratio.

[0181] Furthermore, by using one or more flame-retardant and non-volatile ionic liquids (room-temperature molten salts) as the solvent for the electrolyte, it is possible to prevent the secondary battery from rupturing or igniting even if the internal temperature rises due to internal short circuits, overcharging, etc. Ionic liquids consist of cations and anions, and include organic cations and anions. Examples of organic cations used in electrolytes include aliphatic onium cations such as quaternary ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations, as well as aromatic cations such as imidazolium cations and pyridinium cations. Examples of anions used in electrolytes include monovalent amide anions, monovalent methide anions, fluorosulfonic acid anions, perfluoroalkyl sulfonate anions, tetrafluoroborate anions, perfluoroalkylborate anions, hexafluorophosphate anions, or perfluoroalkyl phosphate anions.

[0182] Examples of salts to be dissolved in the above solvents include LiPF6, LiClO4, LiAsF6, LiBF4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO4, and Li2B. 10 Cl10 , Li2B 12 Cl 12 One kind of lithium salts such as LiCF3SO3, LiC4F9SO3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiN(CF3SO2)2, LiN(C4F9SO2)(CF3SO2), LiN(C2F5SO2)2, etc., or two or more of these can be used in any combination and ratio.

[0183] For the electrolyte used in the secondary battery, it is preferable to use a highly purified electrolyte solution with a low content of particulate dust and elements other than the constituent elements of the electrolyte (hereinafter, also simply referred to as "impurities"). Specifically, it is preferable that the weight ratio of impurities to the electrolyte is 1% or less, preferably 0.1% or less, and more preferably 0.01% or less.

[0184] In addition, additives such as vinylene carbonate, propane sultone (PS), tert-butylbenzene (TBB), fluoroethylene carbonate (FEC), lithium bis(oxalate) borate (LiBOB), and dinitrile compounds such as succinonitrile and adiponitrile may be added to the electrolyte. The concentration of the additive material may be, for example, 0.1 wt% or more and 5 wt% or less based on the entire solvent. VC or LiBOB is particularly preferred because it is easy to form a good film.

[0185] A solution having a solvent and a salt serving as a carrier ion may be referred to as an electrolyte solution.

[0186] A polymer gel electrolyte obtained by swelling a polymer with an electrolyte solution may also be used.

[0187] By using a polymer gel electrolyte, the safety against liquid leakage and the like is enhanced. Also, the secondary battery can be made thinner and lighter.

[0188] As the polymer to be gelled, silicone gel, acrylic gel, acrylonitrile gel, polyethylene oxide-based gel, polypropylene oxide-based gel, fluorine-based polymer gel, etc. can be used.

[0189] Examples of polymers that can be used include polymers having a polyalkylene oxide structure such as polyethylene oxide (PEO), PVDF, polyacrylonitrile, and copolymers containing these. For example, PVDF-HFP, a copolymer of PVDF and hexafluoropropylene (HFP), can be used. The resulting polymer may also have a porous structure.

[0190] Furthermore, a solid electrolyte containing inorganic materials can be used as the electrolyte. For example, sulfide-based solid electrolytes, oxide-based solid electrolytes, halide-based solid electrolytes, etc., can be used. In addition, a solid electrolyte containing polymer materials such as PEO (polyethylene oxide) can be used. When a solid electrolyte is used, the installation of separators and spacers becomes unnecessary. Moreover, since the entire battery can be solidified, the risk of leakage is eliminated, and safety is dramatically improved.

[0191] Sulfide-based solid electrolytes include thiolysicone-based (Li 10 GeP2S 12 Li 3.25 Ge 0.25 P 0.75 S4, etc.), sulfide glass (70Li2S·30P2S5, 30Li2S·26B2S3·44LiI, 63Li2S·36SiS2·1Li3PO4, 57Li2S·38SiS2·5Li4SiO4, 50Li2S·50GeS2, etc.), sulfide crystallized glass (Li7P3S 11 Li 3.25 P 0.95 It contains S4, etc. Sulfide-based solid electrolytes have advantages such as the availability of materials with high conductivity, the ability to be synthesized at low temperatures, and their relatively soft nature which helps maintain conductive paths even after charging and discharging.

[0192] Oxide-based solid electrolytes include materials having a perovskite-type crystal structure (La 2 / 3-x Li 3x Materials having a NASICON-type crystal structure (Li 1-X Al XTi 2-X (PO4)3, etc.), materials having a garnet-type crystal structure (Li7La3Zr2O 12 etc.), materials having a LISICON-type crystal structure (Li 14 ZnGe4O 16 etc.), LLZO (Li7La3Zr2O 12 ), oxide glasses (Li3PO4-Li4SiO4, 50Li4SiO4·50Li3BO3, etc.), oxide crystallized glasses (Li 1.07 Al 0.69 Ti 1.46 (PO4)3, Li 1.5 Al 0.5 Ge 1.5 (PO4)3, etc.) are included. Oxide-based solid electrolytes have the advantage of being stable in the atmosphere.

[0193] Halide-based solid electrolytes include LiAlCl4, Li3InBr6, LiF, LiCl, LiBr, LiI, etc. Also, composite materials in which these halide-based solid electrolytes are filled in the pores of porous aluminum oxide or porous silica can be used as solid electrolytes.

[0194] Also, different solid electrolytes may be mixed and used.

[0195] Among them, Li 1+x Al x Ti 2-x (PO4)3 (0 < x < 1) (hereinafter, LATP) contains aluminum and titanium, which are elements that the positive electrode active material used in the secondary battery 400 of one aspect of the present invention may have. Therefore, a synergistic effect can be expected for improving the cycle characteristics, which is preferable. Also, an improvement in productivity due to reduction of processes can be expected. In this specification, etc., the NASICON-type crystal structure refers to a compound represented by M2(AO4)3 (M: transition metal, A: S, P, As, Mo, W, etc.), which has a structure in which MO6 octahedra and AO4 tetrahedra share vertices and are three-dimensionally arranged.

[0196] [Current collector] The positive electrode current collector 550 can be made of a metal foil containing aluminum, titanium, copper, nickel, or the like. The positive electrode is completed by applying a slurry containing the positive electrode active material layer 571 onto the metal foil and drying it. A carbon material may also be coated onto the metal foil.

[0197] The slurry contains at least a positive electrode active material 561, a binder 555, and a solvent, and preferably further contains a conductive additive 553 and / or a conductive additive 554. The slurry is sometimes called an electrode slurry or an active material slurry, and when forming a positive electrode active material layer, it may be called a positive electrode slurry, and when forming a negative electrode active material layer, it may be called a negative electrode slurry.

[0198] In Figure 10A, the positive electrode active material 561 is shown as particulate, but it is not limited to being particulate. As shown in Figure 10B, the cross-sectional shape of the positive electrode active material 561 may be elliptical, rectangular, trapezoidal, conical, a square with rounded corners, or asymmetrical. Note that during the manufacturing process of the positive electrode, pressing may cause the particulate positive electrode active material to deform into the shape shown in Figure 10B.

[0199] Figure 10C illustrates an example of a cathode using carbon nanotubes instead of graphene, as shown in Figure 10B. Using carbon nanotubes prevents aggregation of carbon black such as acetylene black and improves dispersibility.

[0200] In Figure 10C, the areas not filled with the positive electrode active material 561 and carbon nanotubes are voids, and some areas are impregnated with the electrolyte 556. The positive electrode active material 561 has gaps to facilitate the absorption of the electrolyte 556, and these gaps form voids. Furthermore, although the positive electrode active material 561 may undergo volume changes during charging and discharging, by arranging the electrolyte 556, which contains a fluorine-containing organic solvent such as fluorinated carbonate and an ionic liquid, between multiple positive electrode active material 561, the active materials slide more easily even when volume changes occur during charging and discharging, suppressing cracks and thus improving cycle characteristics. It is important that fluorine-containing organic compounds are present between the multiple active materials that make up the positive electrode.

[0201] A secondary battery can be manufactured using any one of the positive electrodes shown in Figures 10A to 10C. A separator is placed on top of the positive electrode, and the negative electrode is placed on top of the separator. This laminate is then placed in a container (such as an outer casing or metal can), and the container is filled with an electrolyte.

[0202] [Negative electrode] The negative electrode comprises a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer may also contain a conductive additive and a binder.

[0203] <Negative electrode active material> As the negative electrode active material, for example, alloy materials, carbon materials, etc., can be used. In one embodiment of the present invention, the negative electrode active material used in a secondary battery preferably contains fluorine as a halogen. Fluorine has high electronegativity, and the presence of fluorine in the surface layer of the negative electrode active material may have the effect of facilitating the desorption of the solvated solvent at the surface of the negative electrode active material.

[0204] As the negative electrode active material, elements capable of undergoing charge-discharge reactions through alloying and dealloying reactions with lithium can be used. For example, materials containing at least one of silicon, tin, gallium, aluminum, germanium, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc., can be used. Such elements have a larger capacity than carbon, and silicon in particular has a high theoretical capacity of 4200 mAh / g. For this reason, it is preferable to use silicon as the negative electrode active material. Compounds containing these elements may also be used. For example, SiO(silicon monoxide) and SiO X It can also be expressed as (where x is preferably between 0.2 and 1.5), and examples include Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, InSb, SbSn, etc. Here, elements that can undergo charge-discharge reactions by alloying and de-alloying reactions with lithium, and compounds containing such elements, are sometimes called alloying materials.

[0205] Silicon nanoparticles can be used as the negative electrode active material containing silicon. The median diameter (D50) of the silicon nanoparticles is 5 nm or more and less than 1 μm, preferably 10 nm or more and 300 nm or less, and more preferably 10 nm or more and 100 nm or less. The silicon nanoparticles may be crystalline. Furthermore, the silicon nanoparticles may have both crystalline and amorphous regions.

[0206] The silicon-containing negative electrode active material may be in the form of silicon monoxide particles containing one or more silicon crystal grains. The silicon monoxide may be amorphous. The silicon monoxide particles may be carbon-coated. These particles can be mixed with graphite to form the negative electrode active material.

[0207] Suitable carbon-based materials include graphite, easily graphitizable carbon (soft carbon), difficult-to-graphitize carbon (hard carbon), carbon nanotubes, graphene, and carbon black. It is preferable to include fluorine in these carbon-based materials. Fluorine-containing carbon-based materials can also be called particulate or fibrous fluorinated carbon materials. When measuring carbon-based materials by X-ray photoelectron spectroscopy, the fluorine concentration is preferably 1 atomic% or more relative to the sum of the concentrations of fluorine, oxygen, lithium, and carbon.

[0208] Furthermore, while the negative electrode active material may undergo volume changes during charging and discharging, placing fluorine-containing organic compounds such as fluorinated carbonate esters between the negative electrode active materials allows the active materials to slide more easily even when volume changes occur during charging and discharging, suppressing cracking and thus improving cycle characteristics. The presence of fluorine-containing organic compounds between multiple negative electrode active materials is crucial.

[0209] Examples of graphite include artificial graphite and natural graphite. Examples of artificial graphite include mesocarbon microbeads (MCMB), coke-based artificial graphite, and pitch-based artificial graphite. Here, spheroidal graphite having a spherical shape can be used as artificial graphite. For example, MCMB may have a spherical shape and is therefore preferable. Furthermore, it is relatively easy to reduce the surface area of ​​MCMB, which may also be preferable. Examples of natural graphite include flake graphite and spheroidized natural graphite.

[0210] When lithium ions are inserted into graphite (during the formation of lithium-graphite intercalation compounds), graphite exhibits a potential as low as that of lithium metal (0.05V to 0.3V vs. Li / Li). + This allows lithium-ion secondary batteries to exhibit a high operating voltage. Furthermore, graphite is preferred because it has advantages such as a relatively high capacity per unit volume, relatively small volume expansion, low cost, and higher safety compared to lithium metal.

[0211] Furthermore, titanium dioxide (TiO2) and lithium titanium oxide (Li4Ti5O2) are used as negative electrode active materials. 12 ), lithium-graphite intercalation compound (Li x Oxides such as C6, niobium pentoxide (Nb2O5), tungsten oxide (WO2), and molybdenum oxide (MoO2) can be used.

[0212] Furthermore, as the negative electrode active material, a Li3N type structure is used, which is a lithium and transition metal binitride. 3-x M x N(M=Co, Ni, Cu) can be used. For example, Li 2.6 Co 0.4 The N3 has a large charge / discharge capacity (900mAh / g, 1890mAh / cm²). 3 ) indicates a preference.

[0213] Using a lithium-transition metal complex nitride is preferable because it contains lithium ions in the negative electrode active material, allowing it to be combined with lithium-ion-free materials such as V2O5 and Cr3O8 as the positive electrode active material. Even when using a lithium-ion-containing material as the positive electrode active material, the lithium-transition metal complex nitride can be used as the negative electrode active material by pre-desorbing the lithium ions contained in the positive electrode active material.

[0214] Furthermore, materials that undergo a conversion reaction can also be used as the negative electrode active material. For example, transition metal oxides that do not form alloys with lithium, such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO), may be used as the negative electrode active material. The conversion reaction can also occur with oxides such as Fe2O3, CuO, Cu2O, RuO2, Cr2O3, and CoS 0.89 This can also occur with sulfides such as NiS and CuS, nitrides such as Zn3N2, Cu3N, and Ge3N4, phosphides such as NiP2, FeP2, and CoP3, and fluorides such as FeF3 and BiF3.

[0215] Furthermore, lithium can be used as the negative electrode active material. When lithium is used as the negative electrode active material, foil-like lithium can be provided on the negative electrode current collector. Alternatively, lithium may be provided on the negative electrode current collector by vapor deposition or by vapor phase methods such as sputtering. In addition, lithium may be deposited on the negative electrode current collector by electrochemical methods in a solution containing lithium ions.

[0216] The conductive additive and binder that the negative electrode active material layer may have can be the same materials as those used for the conductive additive and binder that the positive electrode active material layer may have.

[0217] Furthermore, in addition to the same materials as the positive electrode current collector, copper and other materials can also be used as the current collector. It is preferable to use a material that does not alloy with carrier ions such as lithium for the negative electrode current collector.

[0218] Furthermore, as another form of the negative electrode of the present invention, a negative electrode without a negative electrode active material can be used. In a secondary battery using a negative electrode without a negative electrode active material, lithium is deposited on the negative electrode current collector during charging, and the lithium on the negative electrode current collector can be dissolved during discharge. Therefore, except in a completely discharged state, the negative electrode current collector will have lithium on it.

[0219] When using a negative electrode without a negative electrode active material, a film may be provided on the negative electrode current collector to homogenize the deposition of lithium. As a film to homogenize the deposition of lithium, for example, a solid electrolyte having lithium ion conductivity can be used. As the solid electrolyte, sulfide particle-based solid electrolytes, oxide-based solid electrolytes, and polymer-based solid electrolytes can be used. Among these, polymer-based solid electrolytes are suitable as a film to homogenize the deposition of lithium because it is relatively easy to form a uniform film on the negative electrode current collector.

[0220] Furthermore, when using a negative electrode without negative electrode active material, a negative electrode current collector with irregularities can be used. When using a negative electrode current collector with irregularities, the recesses in the negative electrode current collector become cavities where lithium can easily be deposited, thus suppressing the formation of dendrite-like shapes when lithium is deposited.

[0221] [Fluorine-modified conductive additive] The conductive additive in the negative electrode can be the same conductive additive that is present in the positive electrode.

[0222] The conductive additive in the negative electrode is preferably modified with fluorine. For example, a material obtained by modifying the conductive additive described above with fluorine can be used as the conductive additive.

[0223] Fluorine modification of conductive additives can be carried out, for example, by treatment with a fluorine-containing gas, heat treatment, plasma treatment in a fluorine-containing gas atmosphere, etc. Examples of fluorine-containing gases that can be used include fluorine gas and methane fluoride (CF4).

[0224] Alternatively, the conductive additive may be immersed in a solution containing, for example, hydrofluoric acid, tetrafluoroborate, or hexafluorophosphoric acid, or a solution containing a fluorine-containing ether compound, as a fluorine modification.

[0225] By modifying the conductive additive with fluorine, the structure of the conductive additive is stabilized, and it is expected that side reactions will be suppressed during the charging and discharging process of the secondary battery. Suppression of side reactions can improve the charging and discharging efficiency. In addition, the decrease in capacity that occurs with repeated charging and discharging can be suppressed. Therefore, by using a fluorine-modified conductive additive in the negative electrode of one aspect of the present invention, a superior secondary battery can be realized.

[0226] By stabilizing the structure of the conductive additive, the conductive properties can be stabilized, and in some cases, high output characteristics can be achieved.

[0227] [Separator] A separator is placed between the positive and negative electrodes. The separator insulates the space between the positive and negative electrodes. It is preferable to use a separator made of a material that is stable to the electrolyte and has excellent liquid retention properties. As separators, for example, materials such as paper and other cellulose fibers, nonwoven fabrics, glass fibers, ceramics, or synthetic fibers made of nylon (polyamide), vinylon (polyvinyl alcohol-based fiber), polyester, polyimide, acrylic, polyolefin, polyurethane can be used.

[0228] The separator preferably has a porosity of 30% to 85%, more preferably 45% to 65%. A higher porosity is preferable as it allows for easier impregnation of the electrolyte. The porosity of the separator may differ between the positive electrode and the negative electrode, and it is preferable that the porosity of the positive electrode is higher than that of the negative electrode. Different porosities can be achieved by using different porosities within the same material, or by using different materials with different porosities. When using different materials, the porosity of the separator can be differed by laminating them.

[0229] The thickness of the separator should be between 5 μm and 200 μm, preferably between 5 μm and 100 μm.

[0230] The separator preferably has an average pore size of 40 nm to 3 μm, more preferably 70 nm to 1 μm. A larger average pore size is preferable as it allows carrier ions to pass through the separator more easily. The average pore size of the separator may differ between the positive and negative electrode sides, and it is preferable that the average pore size on the positive electrode side is larger than that on the negative electrode side. To make the average pore sizes different, a configuration can be used in which the average pore size differs within the same material, or a configuration can be used in which different materials with different average pore sizes are used. When using different materials, the average pore size of the separator can be differed by stacking them.

[0231] The heat resistance of the separator should preferably be 200°C or higher.

[0232] A separator made of polyimide, having a thickness of 10 μm to 50 μm and a porosity of 75% to 85%, is preferable because it improves the output characteristics of the secondary battery.

[0233] The separator may be processed into a bag shape, and the bag-shaped separator may be positioned to enclose or sandwich either the positive or negative electrode.

[0234] The overall film thickness of the separator is preferably 1 μm to 100 μm, and within this range, the separator may be a single-layer or multi-layer structure. In the case of a multi-layer structure, an organic material film such as polypropylene or polyethylene can be coated with a ceramic material, a fluorine material, a polyamide material, or a mixture thereof. As ceramic materials, for example, aluminum oxide particles or silicon oxide particles can be used. As fluorine materials, for example, PVDF or polytetrafluoroethylene can be used. As polyamide materials, for example, nylon or aramid (meta-aramid, para-aramid) can be used.

[0235] Coating the separator surface with ceramic materials improves oxidation resistance, thereby suppressing separator degradation during high-voltage charging and discharging and improving the reliability of secondary batteries. Coating the separator surface with fluorine-based materials improves adhesion between the separator and electrodes, thereby improving output characteristics. Coating the separator surface with polyamide-based materials, particularly aramid, improves heat resistance, thereby enhancing the safety of secondary batteries.

[0236] For example, a polypropylene film may be coated on both sides with a mixture of aluminum oxide and aramid. Alternatively, the side of the polypropylene film in contact with the positive electrode may be coated with a mixture of aluminum oxide and aramid, and the side in contact with the negative electrode may be coated with a fluorine-based material.

[0237] Using such a multilayer separator allows each material to perform its function, ensuring insulation between the positive and negative electrodes even when the overall thickness of the separator is thin, thus maintaining the safety of the secondary battery. This is preferable because it allows for a larger capacity per unit volume of the secondary battery.

[0238] This embodiment can be used in appropriate combination with other embodiments.

[0239] (Embodiment 4) This embodiment shows an example of fabricating an all-solid-state battery using the positive electrode active material obtained in the above embodiment.

[0240] As shown in Figure 11A, a secondary battery 400 according to one embodiment of the present invention has a positive electrode 410, a solid electrolyte layer 420, and a negative electrode 430.

[0241] The positive electrode 410 has a positive electrode current collector 413 and a positive electrode active material layer 414. The positive electrode active material layer 414 has a positive electrode active material 411 and a solid electrolyte 421. The positive electrode active material layer 414 may also have a conductive additive and a binder.

[0242] The solid electrolyte layer 420 has a solid electrolyte 421. The solid electrolyte layer 420 is located between the positive electrode 410 and the negative electrode 430 and is a region that does not contain either the positive electrode active material 411 or the negative electrode active material 431.

[0243] The negative electrode 430 has a negative electrode current collector 433 and a negative electrode active material layer 434. The negative electrode active material layer 434 has a negative electrode active material 431 and a solid electrolyte 421. The negative electrode active material layer 434 may also have a conductive additive and a binder. When metallic lithium is used as the negative electrode active material 431, it is not necessary to form it into particles, so the negative electrode 430 can be made without the solid electrolyte 421, as shown in Figure 11B. Using metallic lithium in the negative electrode 430 is preferable because it can improve the energy density of the secondary battery 400.

[0244] For example, the solid electrolyte 421 in the solid electrolyte layer 420 can be a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halogen-based solid electrolyte, or the like.

[0245] To reiterate, sulfide-based solid electrolytes include thiolysicone-based (Li 10 GeP2S 12 Li 3.25 Ge 0.25 P 0.75 S4, etc.), sulfide glass (70Li2S·30P2S5, 30Li2S·26B2S3·44LiI, 63Li2S·36SiS2·1Li3PO4, 57Li2S·38SiS2·5Li4SiO4, 50Li2S·50GeS2, etc.), sulfide crystallized glass (Li7P3S 11 Li 3.25 P 0.95 It contains S4, etc. Sulfide-based solid electrolytes have advantages such as the availability of materials with high conductivity, the ability to be synthesized at low temperatures, and their relatively soft nature which helps maintain conductive paths even after charging and discharging.

[0246] To reiterate, oxide-based solid electrolytes include materials having a perovskite-type crystal structure (La 2 / 3-x Li 3x Materials having a NASICON-type crystal structure (Li 1-Y Al Y Ti 2-Y (PO4)3 etc.) Materials having a garnet-type crystal structure (Li7La3Zr2O 12 Materials having a LISICON-type crystal structure (Li 14 ZnGe4O 16 etc.), LLZO(Li7La3Zr2O 12 ), oxide glass (Li3PO4-Li4SiO4, 50Li4SiO4·50Li3BO3, etc.), oxide crystallized glass (Li 1.07 Al 0.69 Ti 1.46 (PO4)3, Li 1.5 Al 0.5 Ge 1.5 (PO4)3, etc. are included. Oxide-based solid electrolytes have the advantage of being stable in the atmosphere.

[0247] As described again, halide-based solid electrolytes include LiAlCl4, Li3InBr6, LiF, LiCl, LiBr, LiI, etc. Further, composite materials in which these halide-based solid electrolytes are filled in pores of porous alumina or porous silica can also be used as solid electrolytes.

[0248] Also, different solid electrolytes may be mixed and used.

[0249] As described again, Li 1+x Al x Ti 2-x (PO4)3 (0 < x < 1) (hereinafter referred to as LATP) contains aluminum and titanium, which are elements that the positive electrode active material used in the secondary battery 400 of one aspect of the present invention may have. Therefore, a synergistic effect can be expected for improving cycle characteristics, which is preferable. Also, an improvement in productivity due to reduction of processes can be expected. In this specification and the like, the NASICON-type crystal structure refers to a compound represented by M2(XO4)3 (M: transition metal, X: S, P, As, Mo, W, etc.), which has a structure in which MO6 octahedra and XO4 tetrahedra share vertices and are three-dimensionally arranged.

[0250] This embodiment can be used in appropriate combination with other embodiments.

[0251] (Embodiment 5) In this embodiment, a method for producing a positive electrode active material, which is one aspect of the present invention, by a coprecipitation method will be described using the flowcharts and the like described in FIGS. 12 and 13. Note that FIG. 13 is a flowchart that details some of the procedures in FIG. 12, but the detailed procedures are not necessarily required.

[0252] The transition metal M source 81 (referred to as the M source in the drawing) shown in FIGS. 12 and 13 will be described.

[0253] <Transition metal M source> As the transition metal M, at least one of nickel, cobalt, and manganese can be used. For example, when using only nickel as the transition metal M, two types of transition metals, cobalt and manganese, two types of transition metals, nickel and cobalt, or three types of transition metals, nickel, cobalt, and manganese, can be used.

[0254] When at least one of nickel, cobalt, and manganese is used, it is preferable to use a mixing ratio of nickel, cobalt, and manganese that is within the range that allows for a layered rock salt type crystal structure.

[0255] In particular, a high content of nickel as the transition metal M is preferable because it can result in lower raw material costs compared to cases with a high cobalt content, and can also increase the charge / discharge capacity per unit weight. For example, the nickel content of the transition metal M is preferably more than 25 atomic percent, more preferably 60 atomic percent or more, and even more preferably 80 atomic percent or more. However, if the proportion of nickel is too high, the chemical stability and heat resistance may decrease. Therefore, it is preferable that the nickel content of the transition metal M be 95 atomic percent or less.

[0256] Having cobalt as the transition metal M is preferable because it results in a high average discharge voltage and cobalt contributes to stabilizing the layered rock salt structure, thus enabling a highly reliable secondary battery. However, cobalt is more expensive and unstable than nickel and manganese, so if the proportion of cobalt is too high, the cost of manufacturing the secondary battery may increase. Therefore, it is preferable that the amount of cobalt in the transition metal M is between 2.5 atomic% and 34 atomic%.

[0257] Note that the transition metal M does not necessarily have to include cobalt.

[0258] The presence of manganese as the transition metal M is preferable because it improves heat resistance and chemical stability. However, if the proportion of manganese is too high, the discharge voltage and discharge capacity tend to decrease. Therefore, it is preferable that the amount of manganese in the transition metal M be between 2.5 atomic% and 34 atomic%.

[0259] Note that the transition metal M does not necessarily have to include manganese.

[0260] The transition metal M source 81 is prepared as an aqueous solution containing the transition metal M. As the nickel source, nickel salts such as nickel sulfate, nickel chloride, nickel nitrate, or aqueous solutions of their hydrates can be used. Alternatively, nickel organic acid salts, including nickel acetate, or aqueous solutions of their hydrates can be used. Furthermore, aqueous solutions of nickel alkoxides or organonicickel complexes can be used. In this specification, an organic acid salt refers to a compound of an organic acid such as acetic acid, citric acid, oxalic acid, formic acid, or butyric acid with a metal.

[0261] Similarly, as a cobalt source, cobalt salts such as cobalt sulfate, cobalt chloride, cobalt nitrate, or aqueous solutions of their hydrates can be used. Organic cobalt salts, including cobalt acetate, or aqueous solutions of their hydrates can also be used. Furthermore, aqueous solutions of cobalt alkoxides and organic cobalt complexes can be used.

[0262] Similarly, as a manganese source, manganese salts such as manganese sulfate, manganese chloride, manganese nitrate, or aqueous solutions of these hydrates can be used. Alternatively, organic manganese salts, including manganese acetate, or aqueous solutions of these hydrates can be used. Furthermore, aqueous solutions of manganese alkoxides or organic manganese complexes can be used.

[0263] In this embodiment, as the transition metal M source 81, an aqueous solution is prepared by dissolving nickel sulfate, cobalt sulfate, and manganese sulfate in pure water. At this time, the atomic ratio of nickel, cobalt, and manganese is Ni:Co:Mn = 8:1:1 or close to this. The aqueous solution is acidic.

[0264] A first additive element may be added to the transition metal M source 81. Specifically, the first additive element may be one or more selected from, for example, gallium, aluminum, boron, and indium.

[0265] When the first additive element is gallium, it can be referred to as a gallium source. As a gallium source, a compound containing gallium is used. Examples of gallium-containing compounds include gallium sulfate, gallium chloride, or gallium nitrate, or their hydrates. Alternatively, gallium alkoxides or organic gallium complexes may be used as gallium-containing compounds. Furthermore, organic acids of gallium, such as gallium acetate, or their hydrates may be used as gallium-containing compounds.

[0266] When the first additive element is aluminum, it can be referred to as an aluminum source. As the aluminum source, a compound containing aluminum is used. Examples of aluminum-containing compounds include aluminum sulfate, aluminum chloride, or aluminum nitrate, or their hydrates. Alternatively, aluminum alkoxides or organoaluminum complexes may be used as aluminum-containing compounds. Furthermore, aluminum organic acids, including aluminum acetate, or their hydrates may also be used as aluminum-containing compounds.

[0267] When the first additive element is boron, it can be referred to as a boron source. A compound containing boron is used as the boron source. Examples of boron-containing compounds include boric acid or borate salts.

[0268] When the first additive element is indium, it can be referred to as an indium source. As the indium source, a compound containing indium is used. As the compound containing indium, for example, indium sulfate, indium chloride, or indium nitrate, or their hydrates can be used. Also, as the compound containing indium, indium alkoxide or an organic indium complex may be used. Furthermore, as the compound containing indium, organic acids of indium such as indium acetate, or their hydrates may be used.

[0269] When using a solution as the first additive element, an aqueous solution containing the above compound is prepared.

[0270] Here, the chelating agent 83 shown in FIGS. 12 and 13 will be described.

[0271] <Chelating agent> Examples of the compound constituting the chelating agent include glycine, oxine, 1-nitroso-2-naphthol, 2-mercaptobenzothiazole, or EDTA (ethylenediaminetetraacetic acid). Note that a plurality of types selected from glycine, oxine, 1-nitroso-2-naphthol, or 2-mercaptobenzothiazole may be used. At least one of these is dissolved in water (for example, pure water) and used as a chelating aqueous solution. The chelating agent is more preferable than a general complexing agent in that it is a complexing agent that forms a chelate compound. Of course, a general complexing agent may be used. For example, aqueous ammonia or the like can be used instead of the chelating agent.

[0272] By using the chelating aqueous solution as described above, it is possible to suppress the unnecessary generation of crystal nuclei and promote the growth of crystals, which is preferable. When the generation of unnecessary nuclei is suppressed, the generation of fine particles is suppressed, so that a cobalt compound with a good particle size distribution can be obtained. Also, by using the chelating aqueous solution, the acid-base reaction can be delayed, and a cobalt compound close to spherical can be obtained as the reaction proceeds gradually.

[0273] Glycine, which was used as an example of a compound found in chelate aqueous solutions, has the effect of maintaining a constant pH value between 9 and 10, or around that range. Therefore, using glycine aqueous solution as the chelate aqueous solution is preferable because it makes it easier to control the pH of the reaction vessel when obtaining the above-mentioned cobalt compound.

[0274] <Pure water> The water used in the above-mentioned chelate aqueous solution is preferably pure water. Pure water is defined as water with a resistivity of 1 MΩ·cm or more, more preferably water with a resistivity of 10 MΩ·cm or more, and even more preferably water with a resistivity of 15 MΩ·cm or more. Water that satisfies these resistivity requirements has high purity and contains very few impurities.

[0275] <Step S14> Next, step S14, shown in Figures 12 and 13, will be described. In step S14, the transition metal M source 81 and the chelating agent 83 are mixed to obtain the acid solution 91.

[0276] Next, we will describe the alkaline solution 84 shown in Figures 12 and 13.

[0277] <Alkaline solution> The alkaline solution may be an aqueous solution containing, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, or ammonia, and is not limited to these aqueous solutions as long as it functions as a pH adjuster. For example, an aqueous solution obtained by dissolving several selected substances from sodium hydroxide, potassium hydroxide, or lithium hydroxide in water may also be used. It is preferable to use the above-mentioned pure water.

[0278] Here, we will explain the water 85 shown in Figure 13. Water 85 may be referred to as the starting solution or adjusting solution, and refers to the aqueous solution in the initial state of the reaction. It is preferable to use the above-mentioned pure water, or an aqueous solution obtained by dissolving the above-mentioned chelating agent in the above-mentioned pure water. When a chelating agent is used, as mentioned above, it is possible to suppress the unwanted generation of crystal nuclei and promote growth. Since the generation of unwanted nuclei is suppressed, the formation of fine particles is suppressed, so it is possible to obtain a cobalt compound with a good particle size distribution, or the acid-base reaction can be slowed down, and a cobalt compound that is close to spherical can be obtained as the reaction proceeds gradually. However, as shown in Figure 12, it is not always necessary to use water 85.

[0279] <Step S31> Next, step S31, shown in Figures 12 and 13, will be described. In step S31, the acid solution 91 and the alkali solution 84 are mixed. Through mixing, the acid solution 91 and the alkali solution 84 react to produce a coprecipitate 95.

[0280] The reaction described above in step 31 may be described as a neutralization reaction, an acid-base reaction, or a coprecipitation reaction. The resulting coprecipitation 95 may be described as a precursor of the positive electrode active material.

[0281] <Reaction conditions> When reacting the acid solution 91 with the alkaline solution 84 according to the coprecipitation reaction, the pH of the reaction vessel should be between 9 and 11, preferably between 9.8 and 10.5. This range is preferable because it allows for a larger particle size of the secondary particles in the resulting coprecipitation. Outside this range, productivity will be lower, and the resulting coprecipitation will be more likely to contain impurities.

[0282] When adding the alkaline solution 84 dropwise to the reaction vessel while the acid solution 91 is in place, it is advisable to maintain the pH of the aqueous solution in the reaction vessel within the above-mentioned range. Similarly, when adding the acid solution 91 dropwise to the reaction vessel while the alkaline solution 84 is in place, it is advisable to maintain the pH within the above-mentioned range.

[0283] To further efficiently advance the coprecipitation reaction, it is advisable to add water 85, as shown in Figure 13, to the reaction vessel and add the acid solution 91 dropwise. When the pH of the reaction vessel deviates from a predetermined value due to the addition of the acid solution 91, the pH of the reaction vessel can be controlled by adding the alkaline solution 84 dropwise.

[0284] It is advisable to stir the solution in the reaction vessel using a stirring device. The stirring device may include a stirrer or impeller. The impeller can consist of two to six blades.

[0285] The temperature of the solution in the reaction vessel should be adjusted to be between 50°C and 90°C. It is preferable to start the dropwise addition after the predetermined temperature has been reached. This range is preferable because it allows for a larger particle size in the secondary particles of the resulting co-precipitate 95.

[0286] It is also advisable to install a reflux condenser in the reaction vessel. The reflux condenser allows nitrogen gas to be released from the reaction vessel and water to be returned to the vessel.

[0287] After the above reaction, co-precipitate 95 precipitates in the reaction vessel as a reaction product.

[0288] <Steps S32, S33> Here, we will describe the precipitate 92 shown in Figure 13, the filtration in step S32, and the drying in step S33. The precipitate 92 contains the co-precipitate 95 described above. The precipitate 92 also contains impurities other than the co-precipitate 95. Therefore, in order to recover the co-precipitate 95, filtration in step S32 is preferably performed. Filtration can be performed by suction filtration or reduced pressure filtration. In addition to filtration, centrifugation may also be used. When using suction filtration, it is preferable to wash the reaction product precipitated in the reaction vessel with pure water, and then add an organic solvent with a low boiling point (for example, acetone) before proceeding.

[0289] After filtration, it is advisable to perform drying in step S33. For example, drying is carried out under vacuum at a temperature between 60°C and 90°C for 0.5 hours to 3 hours. In this way, the coprecipitate 95 can be obtained.

[0290] Co-precipitate 95 contains a precursor of the positive electrode active material. The precursor of the positive electrode active material is obtained as secondary particles formed by the aggregation of primary particles. In this specification, primary particles refer to the smallest unit of particles (clumps) that do not have grain boundaries when observed, for example, at 5000x magnification using an SEM (scanning electron microscope). In other words, primary particles refer to the smallest unit of particles surrounded by grain boundaries. Secondary particles refer to particles (particles independent of others) that aggregate so as to share a part of the grain boundary (such as the outer circumference of the primary particles) and do not easily separate. In other words, secondary particles may have grain boundaries.

[0291] Next, a lithium compound is prepared as the lithium source 88 (labeled as Li source in the drawings) as shown in Figures 12 and 13.

[0292] <Lithium compounds> As the lithium compound, lithium hydroxide, lithium carbonate, lithium oxide, or lithium nitrate can be prepared. For example, if cobalt hydroxide is obtained as coprecipitate 95, lithium hydroxide can be used as the lithium compound.

[0293] Lithium compounds should be pulverized. The container used for pulverization, such as a mortar and pestle, should preferably be made of a material that does not easily release impurities. Specifically, a mortar and pestle made of alumina with a purity of 90% or higher, preferably 99% or higher, is recommended. Alternatively, wet pulverization using a ball mill may be used. In wet pulverization, acetone can be used as the solvent.

[0294] <Step S51> Next, step S51, shown in Figures 12 and 13, will be described. In step S51, the co-precipitate 95 and the lithium source 88 are mixed. A mixed mixture 97 is then obtained. A revolving and rotating agitator is preferably used as a means of mixing the co-precipitate 95 and the lithium source 88. Since a revolving and rotating agitator does not use media, grinding is often not performed.

[0295] When mixing and grinding the co-precipitate 95 and lithium source 88 simultaneously, a ball mill or bead mill is preferable. Alumina balls or zirconia balls can be used as the media in the ball mill or bead mill. In a ball mill or bead mill, centrifugal force is applied to the media, enabling finer particle size reduction. However, if contamination from the media is a concern, it is preferable to use the zirconia balls mentioned above.

[0296] When grinding is performed simultaneously, there are two methods: dry grinding and wet grinding. Dry grinding is performed in an inert gas or air, and can grind particles down to a size of 3.5 μm or less, preferably 3 μm or less. Wet grinding is performed in a liquid, and can grind particles down to nano-size. In other words, wet grinding is recommended when you want to reduce the particle size.

[0297] In this way, mixture 97 is obtained.

[0298] Here, we will supplement the heating process using steps S52 and S53 shown in Figure 13.

[0299] <Step S52> Next, step S52 shown in Figure 13 will be described. The heating process may be performed multiple times, and as in step S52, heating may be performed at a temperature of 400°C to 700°C before step S54, which will be described later. Since the heating in step S52 is performed at a lower temperature than step S54, it is sometimes referred to as calcination. Step S52 may release gaseous components contained in the co-precipitate 95 or lithium source 88. By using the material from which the gaseous components have been released, a composite oxide with fewer impurities can be obtained. However, as shown in Figure 12, the positive electrode active material can be obtained without performing the calcination in step S52.

[0300] <Step S53> Next, step S53 shown in Figure 13 will be explained. In step S53, a crushing process is carried out. For example, classification can be performed using a sieve with a mesh diameter of 40 μm or more and 60 μm or less. However, as shown in Figure 12, the positive electrode active material can be obtained without carrying out the crushing process in step S53.

[0301] <Step S54> Next, step S54, shown in Figures 12 and 13, will be described. In step S54, the mixture is heated. Heating yields NCM, which is a composite oxide. This is the positive electrode active material 100. Step S54 is sometimes referred to as the final firing. As can be seen from step S52 and so on, there are numerous heating steps, but to distinguish them from one another, ordinal numbers are sometimes used as appropriate, such as the first heating, the second heating, etc.

[0302] <Heating conditions> The heating temperature is preferably 700°C or higher and less than 1100°C, more preferably 800°C or higher and 1000°C or lower, and even more preferably 800°C or higher and 950°C or lower. When producing cobalt oxide through this heat treatment, the heating is performed at a temperature at which at least the co-precipitate 95 and the lithium source 88 diffuse to each other. This temperature is the reason why it is called the main calcination.

[0303] The heating time can be, for example, between 1 hour and 100 hours, and is preferably between 2 hours and 20 hours.

[0304] The heating atmosphere is preferably an oxygen-containing atmosphere, or a so-called dry air atmosphere with low water content (for example, a dew point of -50°C or lower, more preferably a dew point of -80°C or lower).

[0305] For example, when heating at 750°C for 10 hours, the heating rate should be between 150°C / hour and 250°C / hour. Furthermore, the flow rate of dry air that can form a dry atmosphere should preferably be between 3 L / min and 10 L / min. Regarding the cooling time, it is preferable that it be between 10 and 50 hours from the specified temperature to room temperature, and the cooling rate can be calculated from the cooling time, etc.

[0306] The crucible, sheath, setter, or container used during heating should preferably be made of a material that does not easily release impurities. For example, a crucible made of alumina with a purity of 99.9% is preferable. For mass production, a sheath made of mullite or cordierite (Al2O3, SiO2, MgO) is preferable.

[0307] Furthermore, when collecting the heated material, it is preferable to transfer it from the crucible to a mortar before collection to prevent impurities from contaminating the material. The mortar itself should also be made of a material that does not easily release impurities; specifically, a mortar made of alumina or zirconia with a purity of 90% or higher, preferably 99% or higher, is recommended.

[0308] As described above, positive electrode active material 100 such as NCM can be manufactured. The positive electrode active material 100 can reflect the shape of the precursor co-precipitate 95.

[0309] Furthermore, positive electrode active material 100 such as NCM is preferred because it contains few impurities. However, if sulfides are used as the starting material, sulfur may be detected. The sulfur concentration can be measured by performing elemental analysis of the entire particle of the positive electrode active material using GD-MS, ICP-MS, etc.

[0310] (Embodiment 6) This embodiment describes the process for manufacturing a coated electrode, either a positive or negative electrode.

[0311] A coated electrode refers to a device in which a positive electrode mixture (containing at least positive electrode active material) is formed on a positive electrode current collector, or a negative electrode mixture (containing at least negative electrode active material) is formed on a negative electrode current collector. Each mixture may contain a conductive material or a binder.

[0312] For example, the positive electrode active material, conductive material, and binder shown in the above embodiment are mixed, and a dispersion medium is added to the mixture. After adding the dispersion medium, the mixture is further mixed to form a slurry. The viscosity of the slurry is preferably 80 Pa·s or more and 130 Pa·s or less.

[0313] The slurry described above is applied to the positive electrode current collector and dried, allowing at least the dispersion medium to volatilize. The slurry may then be pressurized and rolled. Pressurization may be performed multiple times at different pressures, with the second pressurization being performed at a higher pressure than the first. In this way, the coated electrode is completed. The thickness of the coated electrode should be between 1 μm and 10 μm. The electrode density at the time of coating should be 3.0 g / cm³. 3 More than 5.0g / cm 3 The following is recommended.

[0314] The positive electrode was explained, but the negative electrode can be manufactured in the same way.

[0315] This embodiment can be used in combination with other embodiments.

[0316] (Embodiment 7) This embodiment describes the process for manufacturing a secondary battery.

[0317] Figure 14 shows an example of the manufacturing process for a secondary battery. In step S110, a coated electrode for the positive electrode and a coated electrode for the negative electrode are prepared. Each coated electrode can be manufactured, for example, according to the embodiment described above.

[0318] In step S120 of Figure 14, each coated electrode is punched out into a desired shape. The tab region is positioned to protrude from the rectangular positive or negative electrode, and the length of one side of the tab region is between 1 / 3 and 1 / 5 of the length of one side of the positive or negative electrode. During the punching process, the area to which the tabs are joined (tab region) is made electrically conductive. For example, the insulating film, etc., is removed from the tab region punched out in a predetermined position using a chemical solution. Acetone, ethanol, or N-methyl-2-pyrrolidone (NMP) can be used as the chemical solution. In this way, the positive and negative electrodes to be mounted in the secondary battery can be obtained in step S130.

[0319] Next, prepare a separator as shown in step S135 of Figure 14, and process the separator in step S140. For example, the cut-out separator can be folded in half and processed into a bag-shaped separator by welding two sides. The width of the welded area should be between 3 nm and 10 nm. Heat of 120°C to 170°C, preferably 130°C to 150°C, may be applied for welding. At this time, placing metal foil in areas that should not be welded (the areas that will become the bag) can prevent welding in unwanted areas.

[0320] Next, as shown in step S150 of Figure 14, the positive and negative electrodes and the separators are assembled. For example, one of the positive and negative electrodes is placed in a bag-shaped separator, and the separator is placed on top of the other of the positive and negative electrodes. Ten positive and ten negative electrodes with single-sided coating are prepared, and five separators are prepared. When placing the positive electrodes in the separators, two positive electrodes are placed with the positive electrode current collectors facing each other. The remaining separators are filled with positive electrodes in the same way. Between the separators, two negative electrodes are placed with the negative electrode current collectors facing each other. There are two sets of separators on the outermost side, but only one negative electrode is placed outside each of them, and the negative electrode active material is positioned so that it faces the separator side. In this way, the structure X can be assembled as shown in step S160. It is preferable to join the tab regions in structure X. For example, the tab region for the positive electrode and the tab region for the negative electrode are joined using an ultrasonic metal bonding machine.

[0321] Next, as shown in step S170 of Figure 14, prepare the positive electrode tab and the negative electrode tab. As shown in step S180, perform chemical treatment to remove insulating film and other materials from the positive electrode tab and the negative electrode tab. Acetone, ethanol, or NMP can be used as the chemical treatment.

[0322] As shown in step S190 of Figure 14, the positive electrode tab and the negative electrode tab are joined to the structure X. The positive electrode tab and the negative electrode tab are joined to the tab area that was joined in step S160, respectively, using an ultrasonic metal bonding device.

[0323] Next, as shown in step S200 of Figure 14, a laminate film is prepared, and as shown in step S210, the laminate film is processed. For example, as part of the processing, a recess is formed in a part of the laminate film having a depth of 1 mm to 10 mm, preferably 1.5 mm to 3 mm.

[0324] Assemble as shown in step S220 of Figure 14. For example, place the structure X with tabs joined to the recesses, fold the laminate film, and weld at least two opposing sides. Apply heat of 150°C to 190°C, preferably 170°C to 180°C. It is also preferable to perform the welding in a dry atmosphere.

[0325] Next, inject the electrolyte as shown in step S230 of Figure 14. It is preferable to inject the electrolyte under an inert atmosphere (an atmosphere containing an inert gas). Weld the remaining edges of the laminate film. It is preferable to weld the remaining edges under a reduced pressure atmosphere.

[0326] Then, as shown in step S240 of Figure 14, the laminated secondary battery is completed.

[0327] <Laminated rechargeable battery> An example of an external view of a laminate-type secondary battery is shown in Figures 15A and 15B. Figures 15A and 15B show a positive electrode 503, a negative electrode 506, a separator 507, an outer casing 509, a positive electrode lead electrode 510, and a negative electrode lead electrode 511, etc. The positive electrode lead electrode 510 and the negative electrode lead electrode 511 may be located on the same side as in Figure 15A, or they may be located on opposite sides as in Figure 15B.

[0328] This embodiment can be used in appropriate combination with other embodiments.

[0329] (Embodiment 8) In this embodiment, other configuration examples of the secondary battery will be explained using Figures 16 and 17.

[0330] [Other structural examples of secondary batteries] The secondary battery 913 shown in Figure 16A has a wound body 950 with terminals 951 and 952 inside a housing 930. The wound body 950 is immersed in an electrolyte inside the housing 930. Terminal 952 is in contact with the housing 930, while terminal 951 is not in contact with the housing 930 due to the use of an insulating material or the like. In Figure 16A, the housing 930 is shown separated for convenience, but in reality, the wound body 950 is covered by the housing 930, and terminals 951 and 952 extend outside the housing 930. The housing 930 can be made of a metal material (e.g., aluminum) or a resin material.

[0331] Furthermore, as shown in Figure 16B, the housing 930 shown in Figure 16A may be formed from multiple materials. For example, in the secondary battery 913 shown in Figure 16B, housing 930a and housing 930b are bonded together, and the winding body 950 is provided in the area surrounded by housing 930a and housing 930b.

[0332] For the housing 930a, an insulating material such as organic resin can be used. In particular, by using a material such as organic resin on the surface where the antenna is formed, shielding of the electric field by the secondary battery 913 can be suppressed. If the shielding of the electric field by housing 930a is small, the antenna may be placed inside housing 930a. For housing 930b, for example, a metal material can be used.

[0333] Furthermore, the structure of the wound body 950 is shown in Figure 16C. The wound body 950 has a negative electrode 931, a positive electrode 932, and a separator 933. The wound body 950 is a wound body in which the negative electrode 931 and the positive electrode 932 are stacked on top of each other with the separator 933 in between, and the stacked sheets are wound up. Note that multiple stacks of the negative electrode 931, positive electrode 932, and separator 933 may be stacked.

[0334] Alternatively, the secondary battery 913 may have a wound body 950a as shown in Figures 17A to 17C. The wound body 950a shown in Figure 17A has a negative electrode 931, a positive electrode 932, and a separator 933. The negative electrode 931 has a negative electrode active material layer 931a. The positive electrode 932 has a positive electrode active material layer 932a.

[0335] By using the positive electrode active material obtained in the above-described embodiment as the positive electrode 932, a secondary battery 913 with high capacity, high charge / discharge capacity, and excellent cycle characteristics can be obtained.

[0336] The separator 933 has a wider width than the negative electrode active material layer 931a and the positive electrode active material layer 932a, and is wound so as to overlap with the negative electrode active material layer 931a and the positive electrode active material layer 932a. Furthermore, it is preferable from a safety standpoint that the negative electrode active material layer 931a is wider than the positive electrode active material layer 932a. A wound body 950a of this shape is also preferable due to its good safety and productivity.

[0337] As shown in Figure 17B, the negative electrode 931 is electrically connected to terminal 951. Terminal 951 is electrically connected to terminal 911a. The positive electrode 932 is electrically connected to terminal 952. Terminal 952 is electrically connected to terminal 911b.

[0338] As shown in Figure 17C, the coiled body 950a and electrolyte are covered by the housing 930, forming a secondary battery 913. It is preferable to provide a safety valve, an overcurrent protection element, etc., in the housing 930. The safety valve is a valve that opens the inside of the housing 930 at a predetermined internal pressure to prevent the battery from rupturing.

[0339] As shown in Figure 17B, the secondary battery 913 may have multiple windings 950a. By using multiple windings 950a, a secondary battery 913 with a larger charge / discharge capacity can be made. Other elements of the secondary battery 913 shown in Figures 17A and 17B can be referenced from the description of the secondary battery 913 shown in Figures 16A to 16C.

[0340] <Cylindrical rechargeable battery> Next, an example of a cylindrical secondary battery will be described with reference to Figure 18. Figure 18A shows an external view of a cylindrical secondary battery 600. Figure 18B is a schematic cross-section of the cylindrical secondary battery 600. As shown in Figure 18B, the cylindrical secondary battery 600 has a positive electrode cap (battery cover) 601 on the top surface and a battery casing (outer casing) 602 on the sides and bottom. These positive electrode cap and battery casing (outer casing) 602 are insulated by a gasket (insulating packing) 610.

[0341] Inside the hollow cylindrical battery casing 602, a battery element is provided, in which a strip-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 in between. Although not shown, the battery element is wound around a center pin. The battery casing 602 is closed at one end and open at the other. The battery casing 602 can be made of a metal such as nickel, aluminum, or titanium, or an alloy thereof, or an alloy of these with another metal (for example, stainless steel), which is corrosion-resistant to the electrolyte. Furthermore, it is preferable to coat the battery casing 602 with nickel or aluminum to prevent corrosion by the electrolyte. Inside the battery casing 602, the battery element, in which the positive electrode, negative electrode, and separator are wound, is sandwiched between a pair of opposing insulating plates 608 and 609. In addition, a non-aqueous electrolyte (not shown) is injected into the inside of the battery casing 602 in which the battery element is provided. The non-aqueous electrolyte can be the same as that used in coin-type secondary batteries.

[0342] Since the positive and negative electrodes used in cylindrical secondary batteries are wound, it is preferable to form active material on both sides of the current collector. A positive electrode terminal (positive electrode current collector lead) 603 is connected to the positive electrode 604, and a negative electrode terminal (negative electrode current collector lead) 607 is connected to the negative electrode 606. Both the positive electrode terminal 603 and the negative electrode terminal 607 can be made of metal materials such as aluminum. The positive electrode terminal 603 is resistance-welded to the safety valve mechanism 612, and the negative electrode terminal 607 is resistance-welded to the bottom of the battery can 602. The safety valve mechanism 612 is electrically connected to the positive electrode cap 601 via a PTC element (Positive Temperature Coefficient) 611. The safety valve mechanism 612 disconnects the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the rise in the internal pressure of the battery exceeds a predetermined threshold. Furthermore, the PTC element 611 is a thermal resistance element whose resistance increases when the temperature rises, and it prevents abnormal heat generation by limiting the current amount through the increase in resistance. Barium titanate (BaTiO3) based semiconductor ceramics can be used for the PTC element.

[0343] Alternatively, as shown in Figure 18C, a module 615 may be constructed by sandwiching multiple secondary batteries 600 between conductive plates 613 and 614. The multiple secondary batteries 600 may be connected in parallel, in series, or connected in parallel and then in series. By constructing a module 615 with multiple secondary batteries 600, a large amount of power can be extracted.

[0344] Figure 18D is a top view of module 615. For clarity, the conductive plate 613 is shown with a dotted line. As shown in Figure 18D, module 615 may have conductors 616 that electrically connect a plurality of secondary batteries 600. A conductive plate can be superimposed on the conductors 616. A temperature control device 617 may also be provided between the plurality of secondary batteries 600. When a secondary battery 600 is overheated, it can be cooled by the temperature control device 617, and when a secondary battery 600 is too cold, it can be heated by the temperature control device 617. This makes the performance of module 615 less susceptible to the ambient temperature. The heat transfer medium in the temperature control device 617 is preferably insulating and non-flammable.

[0345] By using the positive electrode active material described in the previous embodiment for the positive electrode 604, a cylindrical secondary battery 600 with high charge / discharge capacity and excellent cycle characteristics can be obtained.

[0346] (Embodiment 9) This embodiment shows an example in which a battery management system according to one aspect of the present invention is mounted on a mobile body such as a vehicle.

[0347] By installing secondary batteries in vehicles, next-generation clean energy vehicles such as hybrid vehicles (HV), electric vehicles (EV), or plug-in hybrid vehicles (PHV) can be realized. Secondary batteries can also be installed in agricultural machinery, motorized bicycles including electric assist bicycles, motorcycles, electric wheelchairs, electric carts, small or large vessels, submarines, aircraft such as fixed-wing and rotary-wing aircraft, rockets, artificial satellites, space probes, planetary probes, and spacecraft. A secondary battery according to one aspect of the present invention can be a high-capacity secondary battery. Therefore, a secondary battery according to one aspect of the present invention is suitable for miniaturization and weight reduction and can be suitably used in transport vehicles.

[0348] Figure 19 illustrates a mobile device, such as a vehicle, that uses a battery management system according to one aspect of the present invention. The automobile 8400 shown in Figure 19A is an electric vehicle that uses an electric motor as a power source for driving. Alternatively, it is a hybrid vehicle that can appropriately select and use an electric motor and an engine as power sources for driving. By using one aspect of the present invention, it becomes possible to maximize the utilization of the installed secondary battery, thereby realizing a vehicle with a long driving range. The automobile 8400 also has a secondary battery. The secondary battery can not only drive the electric motor 8406 but also supply power to light-emitting devices such as headlights 8401 and interior lights (not shown).

[0349] Furthermore, the secondary battery can supply power to display devices such as the speedometer and tachometer of the 8400 automobile. The secondary battery can also supply power to semiconductor devices such as the navigation system of the 8400 automobile.

[0350] The automobile 8500 shown in Figure 19B can be charged by receiving power from an external charging facility via a plug-in or contactless power supply method to the secondary battery of the automobile 8500. Figure 19B shows the state in which the secondary battery 8024 mounted on the automobile 8500 is being charged from a ground-mounted charging device 8021 via a cable 8022. When charging, the charging method and connector specifications may be carried out as appropriate using a prescribed method such as CHAdeMO® or Combo. The charging device 8021 may be a charging station installed in a commercial facility or a household power supply. For example, the secondary battery 8024 mounted on the automobile 8500 can be charged by an external power supply using plug-in technology. Charging can be performed by converting AC power to DC power via a conversion device such as an AC / DC converter.

[0351] Although not shown in the diagram, the vehicle can also be charged by mounting a power receiving device on the vehicle and receiving power wirelessly from a ground-based power transmission device. In this wireless power supply method, charging can be performed not only when the vehicle is stopped but also while it is in motion by incorporating the power transmission device into the road or exterior wall. Furthermore, this wireless power supply method can be used to transmit and receive power between vehicles. In addition, solar cells can be installed on the exterior of the vehicle to charge the secondary battery when the vehicle is stopped and when it is in motion. For such wireless power supply, electromagnetic induction or magnetic resonance methods can be used.

[0352] Furthermore, Figure 19C shows an example of a motorcycle using a battery management system according to one embodiment of the present invention. The scooter 8600 shown in Figure 19C is equipped with a secondary battery 8602, side mirrors 8601, and turn signals 8603. The secondary battery 8602 can supply electricity to the turn signals 8603.

[0353] Furthermore, the scooter 8600 shown in Figure 19C can accommodate the secondary battery 8602 in the under-seat storage compartment 8604. The secondary battery 8602 can be stored in the under-seat storage compartment 8604 even if the compartment is small. The secondary battery 8602 is removable, so when charging, it can be carried indoors, charged, and then stored back in before riding.

[0354] Figure 19D also shows an example of a satellite using a battery management system according to one embodiment of the present invention. The satellite 8800 shown in Figure 19D has a secondary battery 8801. Since the satellite 8800 will be used in the extremely cold environment of outer space, it is desirable that the secondary battery 8801 be mounted inside the satellite 8800, covered with a heat-insulating material.

[0355] According to one aspect of the present invention, the cycle characteristics of the secondary battery are improved, and the charge and discharge capacity of the secondary battery can be increased. Therefore, the secondary battery itself can be made smaller and lighter. If the secondary battery itself can be made smaller and lighter, it will contribute to the weight reduction of the vehicle, and thus the driving range can be improved. In addition, the secondary battery installed in the vehicle can be used as a power supply source other than the vehicle. In this case, for example, it is possible to avoid using commercial power during peak power demand. By avoiding the use of commercial power during peak power demand, it is possible to contribute to energy saving and the reduction of carbon dioxide emissions. Furthermore, if the cycle characteristics are good, the secondary battery can be used for a long period of time, so the amount of rare metals such as cobalt can be reduced.

[0356] This embodiment can be implemented in appropriate combination with other embodiments. [Explanation of Symbols]

[0357] 1: Server device, 2: Charger, 3: Vehicle, 4: Battery pack, 5: Power receiving connector, 7: Communication network, 11: Data, 41: Secondary battery, 42: Power control unit, 43: Drive motor, 44: Battery cell, 45: Balance circuit, 46: Resistor, 47: Circuit, 50: Vehicle control unit, 51: CPU, 52: Memory unit, 53: Communication unit, 60: Protection circuit, 61: Current monitoring circuit, 62: Voltage monitoring circuit, 63: Temperature monitoring circuit, 64: Path interruption circuit, 71: Start switch

Claims

[Claim 1] Storage batteries and A balance circuit electrically connected to the aforementioned storage battery, The vehicle control unit has a function to control the balance circuit, The aforementioned storage battery has a battery pack having a plurality of battery cells, The vehicle control unit has a function to select the estimated value that is closest to the state of each battery cell in the battery pack. The vehicle has a balance circuit that has the function of controlling the battery cell based on the selected estimated value.

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