Secondary battery management method, management device, management system and management program, and battery-equipped device

Abstract

To provide a method for safely and appropriately managing a secondary battery on the basis of a state of the secondary battery predicted in advance in a period in which diagnosis of the secondary battery is difficult.SOLUTION: In an embodiment, a method for managing a secondary battery is provided. In the management method, in a second period after a first period in which the secondary battery is diagnosed, temperature control of the secondary battery is performed when the secondary battery is charged under a charging condition such that metal lithium is expected to be precipitated in the secondary battery on the basis of, diagnosis results in the first period. In the temperature control of the secondary battery, the temperature of the secondary battery after an end time point and following time point of charging under the above-described charging conditions in the second period is maintained in a predetermined temperature range of above a lower limit temperature or upper and below an upper limit temperature or lower.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a method, a management device, a management system, a management program for a secondary battery, and a battery-equipped device. [Background technology]

[0002] In recent years, secondary batteries such as lithium-ion secondary batteries have been installed in battery-equipped devices such as vehicles, large-scale power storage devices for power systems, smartphones, stationary power supplies, robots, and drones. Such secondary batteries deteriorate over long periods of use due to changes in their internal state from the start of use. For this reason, battery-equipped devices periodically diagnose the secondary batteries by periodically estimating the internal state of the installed secondary batteries. In diagnosing a secondary battery, for example, at least the current and voltage of the secondary battery are measured during charging or discharging, and the measurement results of the current and voltage of the secondary battery are used to estimate the internal state of the secondary battery. Based on the estimated internal state, it is then determined whether metallic lithium has precipitated at the negative electrode of the secondary battery, as well as the degree of deterioration of the positive and negative electrodes.

[0003] From the start of use until the secondary battery is in use, there may be periods during which diagnosing the secondary battery is difficult because sufficient measurement data cannot be obtained to estimate the internal state of the secondary battery with respect to the current and voltage of the secondary battery. For example, during periods when the environmental temperature in which the secondary battery is used is low, such as in winter, the internal resistance of the secondary battery increases, and when the secondary battery is charged, the voltage of the secondary battery reaches the upper limit voltage of the operating range in a short period of time. For this reason, sufficient measurement data cannot be obtained to estimate the internal state of the secondary battery with respect to the current and voltage of the secondary battery, making it difficult to evaluate and diagnose the secondary battery.

[0004] During the operation period in which a secondary battery is in use, even during the period when it is difficult to diagnose the secondary battery as described above, it is required to predict in advance the state of the secondary battery, including whether or not metallic lithium will precipitate on the negative electrode of the secondary battery due to charging. Furthermore, during the period when it is difficult to diagnose the secondary battery, it is required to safely and appropriately manage the secondary battery based on the state of the secondary battery predicted in advance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2010 / 095260 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-181419 [Patent Document 3] Japanese Patent Application Publication No. 2018-147827 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem that the present invention aims to solve is to provide a secondary battery management method, management device, management system and management program, and battery-equipped equipment that safely and appropriately manage secondary batteries based on a pre-predicted state of the secondary battery during periods when diagnosing the secondary battery is difficult. [Means for solving the problem]

[0007] In one embodiment, a method for managing a secondary battery is provided. In the method, when the secondary battery is charged under charging conditions predicted to cause lithium deposition in the secondary battery based on the diagnosis results for a second period after a first period in which the secondary battery is diagnosed, temperature control of the secondary battery is performed. In the temperature control of the secondary battery, the temperature of the secondary battery is maintained within a predetermined temperature range between a lower limit temperature and an upper limit temperature after the end of charging under the charging conditions for the second period. The lower limit temperature of the predetermined temperature range is set based on whether or not it is a temperature at which an oxidation reaction occurs in metallic lithium deposited in the secondary battery, and the upper limit temperature of the predetermined temperature range is set based on the effect on the temperature of the secondary battery of heat generated by the oxidation reaction in metallic lithium deposited in the secondary battery. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a management system according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram illustrating internal state parameters indicating the internal state of a secondary battery. [Figure 3] FIG. 3 is a flowchart showing an example of a diagnostic process and a determination process for a secondary battery, which is performed by a processing unit of a management device according to an embodiment. [Figure 4] FIG. 4 is a flowchart showing an example of processing related to temperature control of the temperature of the secondary battery, which is performed by the processing unit of the management device according to the embodiment. [Figure 5] FIG. 5 is a flowchart showing another example of processing related to temperature control of the temperature of the secondary battery, which is performed by the processing unit of the management device according to the embodiment, different from that shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the drawings.

[0010] Fig. 1 is a schematic diagram showing an example of a management system according to an embodiment. As shown in Fig. 1, the management system 1 includes a battery-equipped device 2 and a management device 3. The battery-equipped device 2 is equipped with a secondary battery 5, a measurement circuit 6, a temperature regulator 7, and a battery control unit 8. Examples of the battery-equipped device 2 include vehicles, large-scale power storage devices for power systems, smartphones, stationary power supply devices, robots, drones, etc., and examples of vehicles that can be the battery-equipped device 2 include railcars, electric buses, electric cars, plug-in hybrid cars, and electric motorcycles, etc.

[0011] The secondary battery 5 is, for example, a lithium ion secondary battery. The secondary battery 5 may be formed from a single cell (single battery), or may be a battery module or cell block formed by electrically connecting a plurality of single cells. When the secondary battery 5 is formed from a plurality of single cells, the plurality of single cells may be electrically connected in series or in parallel in the secondary battery 5. Furthermore, the secondary battery 5 may have both a series connection structure in which a plurality of single cells are connected in series and a parallel connection structure in which a plurality of single cells are connected in parallel. Furthermore, the secondary battery 5 may be any of a battery string, a battery array, and a storage battery in which a plurality of battery modules are electrically connected.

[0012] The measurement circuit 6 detects and measures parameters related to the secondary battery 5 while the secondary battery 5 is being charged or discharged. For example, the measurement circuit 6 measures the parameters periodically at a predetermined timing during one charge or discharge of the secondary battery 5. In this case, the measurement circuit 6 measures the parameters related to the secondary battery 5 at each of multiple measurement points during one charge or discharge of the secondary battery 5, and measures the parameters related to the secondary battery 5 multiple times. The parameters related to the secondary battery 5 include the current flowing through the secondary battery 5, the voltage of the secondary battery 5, and the temperature of the secondary battery 5. For this reason, the measurement circuit 6 includes an ammeter that measures the current, a voltmeter that measures the voltage, and a temperature sensor that measures the temperature.

[0013] The measurement circuit 6 also measures the environmental temperature of the environment in which the secondary battery 5 is used, i.e., the environment in which the battery-equipped device 2 is located. The environmental temperature is the outside air temperature where the secondary battery 5 and battery-equipped device 2 are located. The environmental temperature for a given period of time is determined by the average outside air temperature of the location where the secondary battery 5 and battery-equipped device 2 are located for that given period of time. In some situations, the temperature of the secondary battery 5 is the same as or approximately the same as the environmental temperature of the environment in which the secondary battery 5 is used. In other situations, the temperature of the secondary battery 5 is higher than the environmental temperature of the environment in which the secondary battery 5 is used due to heat generated by charging and discharging the secondary battery 5. For example, suppose the vehicle that serves as the battery-equipped device 2 is parked in a parking lot. In this case, the temperature of the parking lot is the environmental temperature of the environment in which the secondary battery 5 is used. Note that even in the same location, the environmental temperature varies depending on the season, the time of day, and the like.

[0014] The temperature regulator 7 includes a heater, a cooler, and the like. The temperature regulator 7 heats or cools the secondary battery 5 when activated. The battery control unit 8 controls the operation of the secondary battery 5 by controlling the charging and discharging of the secondary battery 5, and the like. The battery control unit 8 also controls the operation of the temperature regulator 7 to adjust the temperature of the secondary battery 5 and perform temperature control of the secondary battery 5. The temperature control of the secondary battery 5 is performed based on the measurement results of the temperature of the secondary battery 5 by the measurement circuit 6, and the like.

[0015] The battery control unit 8 constitutes a processing device (computer) and includes a processor and a storage medium. The processor includes any of a CPU (Central Processing Unit), ASIC (Application Specific Integrated Circuit), microcomputer, FPGA (Field Programmable Gate Array), and DSP (Digital Signal Processor). The storage medium may include a main storage device such as a memory, as well as an auxiliary storage device. Examples of storage media include a magnetic disk, an optical disk (CD-ROM, CD-R, DVD, etc.), a magneto-optical disk (MO, etc.), and a semiconductor memory. The battery control unit 8 may include one or more processors and storage media. The processor of the battery control unit 8 performs processing by executing a program stored in a storage medium or the like. The program executed by the processor of the battery control unit 8 may be stored in a computer (server) connected via a network such as the Internet, or in a server in a cloud environment. In this case, the processor downloads the program via the network.

[0016] The management device 3 manages the secondary battery 5, including diagnosing the secondary battery 5, based on information about the secondary battery 5. Therefore, the secondary battery 5 is a target for management by the management device 3. In the example of FIG. 1 , the management device 3 is provided outside the battery-equipped device 2. The management device 3 includes a processing unit 11, a data storage unit 12, and a transmitting / receiving unit 13. The processing unit 11 includes a battery diagnosis unit 15, a determination unit 16, and a control command generation unit 17. The battery diagnosis unit 15, the determination unit 16, and the control command generation unit 17 each perform part of the processing performed by the processing unit 11.

[0017] The management device 3 is, for example, a server that can communicate with the battery control unit 8 via a network. In this case, the management device 3 includes a processor and a storage medium, similar to the battery control unit 8. The processing unit 11 performs part of the processing performed by the processor, etc. of the management device 3, and the storage medium of the management device 3 functions as the data storage unit 12. The transmission / reception unit 13 is composed of an interface, etc. of the processing device, and the management device 3 can communicate with other processing devices, such as the battery control unit 8 of the battery-equipped device 2, via the transmission / reception unit 13.

[0018] In one example, the management device 3 may be a cloud server configured in a cloud environment. The infrastructure of a cloud environment is configured by a virtual processor such as a virtual CPU and a cloud memory. Therefore, when the management device 3 is a cloud server, the processing unit 11 performs part of the processing performed by the virtual processor. The cloud memory functions as the data storage unit 12. The transmission / reception unit 13 is configured by an interface with the cloud environment, etc., and the management device 3 serving as a cloud server can communicate with processing units such as the battery control unit 8 of the battery-equipped device 2 via the transmission / reception unit 13.

[0019] The data storage unit 12 may also be provided in a computer separate from the battery control unit 8 and management device 3. In this case, the management device 3 is connected via a network to the computer in which the data storage unit 12 and the like are provided. The management device 3 may also be provided in the battery-equipped device 2. In this case, the management device 3 is composed of a processing device and the like provided in the battery-equipped device 2. In addition, when the management device 3 is provided in the battery-equipped device 2, one processing device and the like provided in the battery-equipped device 2 may perform the processing of the management device 3, which will be described later, as well as the processing of the battery control unit 8, such as controlling the charging and discharging of the secondary battery 5. The processing of the management device 3 will be described below.

[0020] The processor etc. of the management device 3 performs diagnosis on the target secondary battery 5, including estimating the internal state and determining the degree of deterioration of each of the positive and negative electrodes. Diagnosis of the secondary battery 5 is performed periodically, for example, after the secondary battery 5 starts to be used. In diagnosing the secondary battery 5, a control command from the control command generation unit 17 of the processing unit 11 of the management device 3 is transmitted to the battery control unit 8 via the transceiver unit 13, and the battery control unit 8 charges or discharges the secondary battery 5 under predetermined conditions based on the received control command.

[0021] Here, data indicating the predetermined conditions for charging or discharging the secondary battery 5 performed in diagnosing the secondary battery 5 is stored in, for example, the data storage unit 12. The predetermined conditions include, for example, a condition related to the SOC (state of charge) at the start of charging or discharging, a condition related to the SOC range of the secondary battery 5 during charging or discharging, a condition related to the current flowing through the secondary battery 5 during charging or discharging (the C rate of the secondary battery 5), a condition related to the temperature of the secondary battery 5 during charging or discharging, a condition related to the environmental temperature of the environment in which the secondary battery 5 is charged or discharged, and a condition for terminating charging or discharging.

[0022] Under the predetermined conditions, the current value of the current of the secondary battery 5 is set to a relatively small value. Therefore, in the diagnosis of the secondary battery 5, the secondary battery 5 is charged or discharged at a relatively low rate. Furthermore, under the predetermined conditions, the SOC range is set to a relatively wide range. Therefore, in the diagnosis of the secondary battery 5, the secondary battery 5 is charged or discharged within a relatively wide SOC range. Furthermore, under the predetermined conditions, the environmental temperature is set to a normal temperature range, approximately equal to room temperature, for example, a range of 15°C to 35°C. Therefore, in the diagnosis of the secondary battery 5, the secondary battery 5 is charged or discharged in an environment where the environmental temperature is within the normal temperature range.

[0023] In diagnosing the secondary battery 5, the measurement circuit 6 measures the aforementioned parameters related to the secondary battery 5 while the secondary battery 5 is being charged or discharged under the aforementioned predetermined conditions. Then, in the management device 3, measurement data indicating the measurement results of the measurement circuit 6 of the aforementioned parameters related to the secondary battery 5 is received by the transceiver 13, and the received measurement data is acquired by the processing unit 11. The measurement data is generated by the battery control unit 8, for example, based on the measurement results of the measurement circuit 6, etc.

[0024] When the secondary battery 5 is being charged or discharged under the above-mentioned predetermined conditions, the measurement circuit 6 measures parameters related to the secondary battery 5 at each of a plurality of measurement points. Therefore, the measurement data received by the transmitter / receiver 13 includes measurement values of the parameters related to the secondary battery 5 at each of the plurality of measurement points (a plurality of measurements). The measurement data also includes changes over time (time history) of the parameters related to the secondary battery 5 when the secondary battery 5 is being charged or discharged under the above-mentioned predetermined conditions. Therefore, the measurement data includes changes over time (time history) of the current of the secondary battery 5, changes over time (time history) of the voltage of the secondary battery 5, and changes over time (time history) of the temperature of the secondary battery 5, etc.

[0025] Furthermore, either the battery control unit 8 or the processing unit 11 (processor) of the management device 3 may estimate time changes (time history) of either the charge amount or SOC of the secondary battery 5 during charging or discharging under the above-mentioned predetermined conditions, based on the measurement results of the measurement circuit 6 of parameters related to the secondary battery 5. The measurement data may include data indicating the relationship between the estimated charge amount or SOC of the secondary battery 5 and the measured parameter related to the secondary battery 5. In this case, for example, the measurement data includes data indicating the relationship between the estimated charge amount or SOC of the secondary battery 5 and the measured voltage of the secondary battery 5. The processing unit 11 can write the above-mentioned measurement data to the data storage unit 12.

[0026] Here, the charge amount of the secondary battery 5 can be calculated based on the charge amount (SOC) of the secondary battery 5 at the start of charging or discharging under the above-mentioned predetermined conditions and the change over time in the current of the secondary battery 5. In this case, the charge amount of the secondary battery 5 is calculated by a current integration method. The charge amount of the secondary battery 5 can also be calculated by a calculation method using the relationship between the terminal voltage of the secondary battery 5 and the charge amount, an estimation method using a Kalman filter, or the like.

[0027] The SOC of the secondary battery 5 is defined based on, for example, the voltage of the secondary battery 5. For the secondary battery 5, a lower limit voltage Vmin and an upper limit voltage Vmax are defined for the voltage. For example, a state in which the open circuit voltage (OCV) or the voltage during discharge under certain specified conditions reaches the lower limit voltage Vmin is defined as a state in which the SOC is 0%. A state in which the open circuit voltage or the voltage during charge under certain specified conditions reaches the upper limit voltage Vmax is defined as a state in which the SOC is 100%. For the secondary battery 5, the discharge capacity from a state in which the SOC is 100% to a state in which the SOC is 0% or the charge capacity from a state in which the SOC is 0% to a state in which the SOC is 100% is defined as the battery capacity. For the secondary battery 5, the ratio of the remaining charge amount up to a state in which the SOC is 0% to the battery capacity is defined as the SOC. Therefore, the SOC of the secondary battery 5 can be calculated based on the charge amount of the secondary battery 5, etc.

[0028] In diagnosing the secondary battery 5, the battery diagnostic unit 15 acquires the measurement data described above and estimates the internal state of the secondary battery 5 based on the measurement data. In this embodiment, the battery diagnostic unit 15 estimates internal state parameters that indicate the internal state of the secondary battery 5. In one example, the battery diagnostic unit 15 analyzes at least data that indicates the time changes in the current and voltage of the secondary battery 5 when it is charged or discharged under the above-mentioned predetermined conditions. In this case, the battery diagnostic unit 15 performs a charge curve analysis or a discharge curve analysis of the secondary battery 5. Furthermore, the battery diagnostic unit 15 may analyze data that indicates the time changes in the temperature of the secondary battery 5, in addition to the data that indicates the time changes in the current and voltage of the secondary battery 5.

[0029] FIG. 2 is a schematic diagram illustrating internal state parameters that indicate the internal state of a secondary battery. In FIG. 2, the horizontal axis represents the charge amount Q, and the vertical axis represents the potential E. As shown in FIG. 2, a lower limit potential Epmin and an upper limit potential Epmax are defined for the positive electrode potential of the secondary battery 5, and the positive electrode potential increases as the charge amount of the positive electrode increases. Furthermore, the charge amount at which the positive electrode potential reaches the lower limit potential Epmin is the initial charge amount Qpmin of the positive electrode, and the charge amount at which the positive electrode potential reaches the upper limit potential Epmax is the upper limit charge amount Qpmax of the positive electrode. The charge amount of the positive electrode from the initial charge amount Qpmin to the upper limit charge amount Qpmax is the positive electrode capacity Mp of the secondary battery 5, which corresponds to the charge / discharge capacity of the positive electrode of the secondary battery 5.

[0030] In the secondary battery 5, a lower limit potential Enmin and an upper limit potential Enmax are defined for the negative electrode potential, and the negative electrode potential decreases as the charge amount of the negative electrode increases. Furthermore, the charge amount at which the negative electrode potential reaches the upper limit potential Enmax is the initial charge amount Qnmin of the negative electrode, and the charge amount at which the negative electrode potential reaches the lower limit potential Enmin is the upper limit charge amount Qnmax of the negative electrode. The charge amount of the negative electrode from the initial charge amount Qnmin to the upper limit charge amount Qnmax is the negative electrode capacity Mn of the secondary battery 5, which corresponds to the charge / discharge capacity of the negative electrode of the secondary battery 5.

[0031] The internal state parameters of the secondary battery 5 include the positive electrode capacity Mp, negative electrode capacity Mn, the initial charge amount Qpmin of the positive electrode, and the initial charge amount Qnmin of the negative electrode. The internal state parameters of the secondary battery 5 also include the positive electrode mass, which is a parameter corresponding to the positive electrode capacity Mp, and the negative electrode mass, which is a parameter corresponding to the negative electrode capacity Mn. The positive electrode mass can be calculated based on the positive electrode capacity and the type of material forming the positive electrode. Similarly, the negative electrode mass can be calculated based on the negative electrode capacity and the type of material forming the negative electrode. The internal state parameters of the secondary battery 5 also include the positive electrode capacity retention rate and the negative electrode capacity retention rate. Here, the positive electrode capacity retention rate is the ratio of the estimated positive electrode capacity to the positive electrode capacity at the start of use of the secondary battery 5, and the negative electrode capacity retention rate of the secondary battery 5 is the ratio of the estimated negative electrode capacity to the negative electrode capacity at the start of use.

[0032] The internal state parameters of the secondary battery 5 also include an operation window shift (SOW), which is the difference between the initial charge amount Qpmin of the positive electrode and the initial charge amount Qnmin of the negative electrode. The internal state parameters of the secondary battery 5 also include a parameter related to the internal resistance of the secondary battery 5. The parameters related to the internal resistance may include the resistance of each of the positive electrode and the negative electrode in addition to the internal resistance of the entire secondary battery 5. Note that FIG. 2 also shows the battery capacity Mb, which is one of the battery characteristics of the secondary battery 5. As described above, the battery capacity Mb corresponds to the charge amount required for the voltage of the secondary battery 5 (the difference between the positive electrode potential and the negative electrode potential) to reach the upper limit voltage Vmax from the lower limit voltage Vmin.

[0033] In this embodiment, a battery model of the secondary battery 5 is stored in the data storage unit 12. The battery model includes data indicating the relationship of the internal state of the secondary battery 5 to at least one of the voltage and current of the secondary battery 5, and includes, for example, a calculation formula for calculating at least one of the voltage and current of the secondary battery 5 from the internal state of the secondary battery 5. Therefore, the battery model includes data indicating the relationship of internal state parameters such as the positive electrode capacity and the negative electrode capacity to at least one of the current and voltage of the secondary battery 5. Note that the relationship of the internal state to each of the current and voltage of the secondary battery 5 changes in response to the temperature of the secondary battery 5, etc. Therefore, in the battery model of the secondary battery 5, the relationship of the internal state to at least one of the current and voltage of the secondary battery 5 may be set for each of a plurality of temperatures that are different from each other.

[0034] In the aforementioned charge curve analysis or discharge curve analysis of the secondary battery 5, the battery diagnostic unit 15 performs a fitting calculation (regression calculation) using at least the measurement results of the voltage and current of the secondary battery 5 included in the measurement data and data indicating the relationship between the voltage and current of the secondary battery 5 and the internal state of the secondary battery 5. In this case, the fitting calculation is performed using one or more internal state parameters as variables in a calculation formula that calculates at least the voltage and current of the secondary battery 5 from the internal state of the secondary battery 5. The battery diagnostic unit 15 then estimates the internal state of the secondary battery 5 by calculating one or more internal state parameters that serve as variables through the fitting calculation. The battery diagnostic unit 15 can write the estimation results of the internal state of the secondary battery 5, including the estimated values of the internal state parameters of the secondary battery 5, to the data storage unit 18. Note that the fitting calculation to calculate the internal state parameters may use, in addition to the measurement results of the voltage and current of the secondary battery 5 and data indicating the relationship between the voltage and current of the secondary battery 5 and the internal state of the secondary battery 5, the measurement results of the temperature of the secondary battery 5 and data indicating the relationship between the temperature of the secondary battery 5 and the internal state of the secondary battery 5.

[0035] In one example, the battery model includes the calculation formula (1) as data indicating the relationship between the internal state of the secondary battery 5 and the voltage V(t) of the secondary battery 5 at a certain time t. The battery diagnosis unit 15 estimates the internal state of the secondary battery 5 by performing a fitting calculation using the measurement result of the voltage V(t) of the secondary battery 5 included in the measurement data and the calculation formula (1) included in the battery model. In the fitting calculation using formula (1), for example, the positive electrode capacity Mp, the negative electrode capacity Mn, the positive electrode initial charge amount Qpmin, the negative electrode initial charge amount Qnmin, and a parameter R related to the internal resistance are set as internal state parameters, and the fitting calculation is performed using these internal state parameters as variables.

[0036]

number

[0037] In formula (1), I represents the current of the secondary battery 5, and a measured value included in the measurement data or the like is used as the current I. In formula (1), Ep(Mp, Qpmin) represents a function that calculates the open circuit potential (OCP) of the positive electrode using as variables at least the positive electrode capacity Mp and the initial charge amount Qpmin of the positive electrode, and En(Mn, Qnmin) represents a function that calculates the open circuit potential of the negative electrode using as variables at least the negative electrode capacity Mn and the initial charge amount Qnmin of the negative electrode.

[0038] A method for estimating the internal state of a secondary battery by charging curve analysis is disclosed in Patent Document 3 (JP 2018-147827 A). In Patent Document 3, the internal state of the secondary battery is also estimated by performing a fitting calculation using at least measurement results of the current and voltage of the secondary battery and data indicating the relationship between the internal state of the secondary battery and the voltage and current of the secondary battery. In an embodiment, the internal state of the secondary battery 5 may be estimated in the same manner as in Patent Document 3. In estimating the internal state of the secondary battery 5, the battery diagnostic unit 15 reads a voltage model including the calculation formula of Equation (1) from the data storage unit 12. In addition, the battery diagnostic unit 15 can store, in the data storage unit 12, tentative estimates and final estimates of the internal state parameters that are required for subsequent processing.

[0039] Furthermore, the battery diagnostic unit 15 may estimate the battery characteristics of the secondary battery 5 based on the estimated internal state of the secondary battery 5. The battery characteristics of the secondary battery 5 include the open circuit voltage and OCV curve of the secondary battery 5 in addition to the battery capacity Mb described above. Here, the OCV curve is a function that indicates the relationship between a parameter other than the OCV and the OCV, such as a function that indicates the relationship between the OCV and the SOC or the charge amount. Furthermore, the internal resistance of the entire secondary battery 5 indicates the internal state of the secondary battery 5 as described above, and also indicates the battery characteristics of the secondary battery 5. Patent Document 3 discloses a method for estimating the battery characteristics of the secondary battery 5 based on the internal state of the secondary battery 5. In an embodiment, the battery characteristics of the secondary battery 5 may be estimated in a manner similar to that of Patent Document 3.

[0040] Furthermore, in diagnosing the secondary battery 5, the battery diagnostic unit 15 determines the real-time deterioration levels of the positive and negative electrodes based on the estimated internal state of the secondary battery 5. In one example, the deterioration level of the positive electrode is determined based on the estimated results of any one of the positive electrode capacity Mp, the initial charge amount Qpmin of the positive electrode, the SOW, and the positive electrode resistance. The smaller the positive electrode capacity Mp, the higher the deterioration level of the positive electrode is determined to be. Furthermore, the larger the change in the resistance of the positive electrode since the start of use of the secondary battery 5, the higher the deterioration level of the positive electrode is determined to be.

[0041] In one example, the degree of deterioration of the negative electrode is determined based on the estimated results of any one of the negative electrode capacity Mn, the initial charge amount Qnmin of the negative electrode, the SOW, and the resistance of the negative electrode. The smaller the negative electrode capacity Mn, the higher the degree of deterioration of the negative electrode is determined. The greater the changes in the initial charge amount Qnmin and the SOW since the start of use of the secondary battery 5, the higher the degree of deterioration of the negative electrode is determined. In particular, when the negative electrode capacity Mn is small and the SOW increases rapidly, it is determined that metallic lithium deposition has occurred. The greater the change in the resistance of the negative electrode since the start of use of the secondary battery 5, the higher the degree of deterioration of the negative electrode is determined. The battery diagnostic unit 15 may calculate parameters indicating the degree of deterioration for each of the positive electrode and the negative electrode in determining the degree of deterioration of each of the positive electrode and the negative electrode. In this case, the parameter is calculated to be a larger value for each of the positive electrode and the negative electrode, as the degree of deterioration of each of the positive electrode and the negative electrode increases. The battery diagnostic unit 15 can write the results of the determination of the degree of deterioration of each of the positive and negative electrodes into the data storage unit 12.

[0042] The determination unit 16 acquires real-time diagnostic results for the secondary battery 5. The determination unit 16 then makes a determination based on the real-time deterioration degree of the negative electrode included in the diagnostic results for the secondary battery 5. In the determination based on the deterioration degree of the negative electrode, a first reference level and a second reference level that is higher than the first reference level are set for the deterioration degree of the negative electrode. Here, the period during which the diagnosis of the secondary battery 5 is performed is defined as the first period. The determination unit 16 determines whether the deterioration of the negative electrode exceeds the first reference level during the first period. That is, the determination unit 16 determines whether the deterioration degree of the negative electrode of the secondary battery 5 exceeds the first reference level based on the internal state of the secondary battery 5 during the first period. Furthermore, if the deterioration of the negative electrode exceeds the first reference level during the first period during which the diagnosis is performed in real time, the determination unit 16 determines whether the deterioration degree of the negative electrode during the first period exceeds the second reference level.

[0043] In one example, in diagnosing secondary battery 5, as described above, parameter α indicating the degree of deterioration of the negative electrode is calculated, and a threshold value αth1 and a threshold value αth2 greater than threshold value αth1 are set for parameter α. Then, based on the calculated value of parameter α in the diagnosis for the first period being greater than threshold value αth1, it is determined that the degree of deterioration of the negative electrode in the first period has exceeded a first reference level. Furthermore, based on the calculated value of parameter α in the diagnosis for the first period being greater than threshold value αth2, it is determined that the degree of deterioration of the negative electrode in the first period has exceeded a second reference level.

[0044] Furthermore, if the degree of deterioration of the negative electrode during the first period exceeds a second reference level, the determination unit 16 determines that metallic lithium has precipitated on the negative electrode during the first period. Furthermore, if the degree of deterioration of the negative electrode during the first period exceeds the second reference level, the control command generation unit 17 transmits, for example, a control command to stop the use of the secondary battery 5 to the battery control unit 8 via the transceiver unit 13. Then, based on the received control command, the battery control unit 8 forcibly stops the use of the secondary battery 5 by, for example, making the secondary battery 5 unable to be charged or discharged. Furthermore, if the degree of deterioration of the negative electrode during the first period exceeds the second reference level, instead of or in addition to forcibly stopping the use of the secondary battery 5, the processing unit 11 or the like may issue a warning to stop the use of the secondary battery 5. In this case, the warning is issued using a user interface (not shown) or the like, and is issued by either a screen display, a voice, or the like.

[0045] Furthermore, the determination unit 16 predicts the state of the secondary battery 5 at a second time after the first period based on the diagnosis result of the secondary battery 5 during the first period. In one example, each of the four seasons is set as a period that can be the first period, the second period, etc. For example, if summer is the first period, autumn is the second period, and if autumn is the first period, winter is the second period. In another example, four time periods, morning, daytime, evening, and night, are defined in a day, and each of the four time periods is set as a period that can be the first period, the second period, etc. For example, if daytime is the first period, evening is the second period, and if evening is the first period, night is the second period.

[0046] If the degree of deterioration of the negative electrode of the secondary battery 5 during the first period exceeds the first reference level and is equal to or lower than the second reference level, the determination unit 16 acquires charging conditions for charging the secondary battery 5 scheduled to be performed during the second period. The determination unit 16 acquires, as the charging conditions for charging the secondary battery 5 during the second period, conditions related to the SOC range of the secondary battery 5 during charging, conditions related to the current flowing through the secondary battery 5 during charging (the C rate of the secondary battery 5), and conditions related to the ambient temperature of the environment where charging is performed. Information related to the charging conditions for charging the secondary battery 5 during the second period may be stored in the data storage unit 12 or may be input by an operator or the like using a user interface or the like. Furthermore, the ambient temperature of the environment where charging of the secondary battery 5 during the second period, etc. may be searched for via a network. For example, in a case where autumn is the first period and winter is the second period, the environmental temperature of the environment where the secondary battery 5 is charged in the second period (winter) may be acquired based on a temperature forecast for the second period (winter) in a weather forecast, etc. The environmental temperature in the second period is defined by the average value in the second period of the outdoor air temperature, etc., of the location where the secondary battery 5 and the battery-equipped device 2 are located. Note that the environmental temperature in the first period is also defined by the average value in the first period of the outdoor air temperature, etc., of the location where the secondary battery 5 and the battery-equipped device 2 are located, similar to the environmental temperature in the second period.

[0047] If the degree of deterioration of the negative electrode of the secondary battery 5 during the first period exceeds a first reference level and is equal to or lower than a second reference level, the determination unit 16 predicts whether metallic lithium will be deposited on the negative electrode of the secondary battery 5 by charging under the charging conditions acquired during the second period, based on the charging conditions for charging the secondary battery 5 during the second period. If it is predicted that metallic lithium will be deposited on the secondary battery 5 during the second period, the determination unit 16 determines to perform temperature control of the secondary battery 5 (described later) after the end of charging under the charging conditions predicted to cause metallic lithium to be deposited during the second period. Therefore, in this embodiment, based on the diagnosis result of the secondary battery 5 during the first period, including the estimation result of the internal state of the secondary battery 5 during the first period, and the charging conditions for charging the secondary battery 5 scheduled to be performed during the second period, it is determined whether to perform temperature control of the temperature of the secondary battery 5 after the end of charging during the second period.

[0048] In one example, when the degree of deterioration of the negative electrode of the secondary battery 5 during a first period exceeds a first reference level and is equal to or lower than a second reference level, it is determined that temperature control of the secondary battery 5 will be performed after the end of charging during the second period based on the fact that the environmental temperature in which the secondary battery 5 is charged during the second period is low, for example, 10°C or lower. In this example, it is assumed that the degree of deterioration of the negative electrode of the secondary battery 5 during the first period (autumn) exceeds the first reference level and is equal to or lower than the second reference level. It is also assumed that the secondary battery 5 will be charged during the second period (winter) in an environment where the environmental temperature is low, for example, 10°C or lower. In this case, it is determined in advance, prior to the second period, that temperature control of the temperature of the secondary battery 5 will be performed after the end of charging during the second period (winter).

[0049] Furthermore, it is assumed that the determination unit 16 predicts, based on the charging conditions and the like for charging the secondary battery 5 during the second period, that metallic lithium will not be deposited in the secondary battery 5 due to charging and the like during the second period. In this case, the determination unit 16 determines that temperature control of the temperature of the secondary battery 5 will not be performed during the second period. For example, it is assumed that the first period is summer and the second period is autumn. In this case, even if it is determined that the real-time deterioration degree of the negative electrode of the secondary battery 5 exceeds the first reference level and is equal to or lower than the second reference level during the first period (summer), the secondary battery 5 is charged within a room temperature range of, for example, 15°C or higher and 35°C or lower during the second period (autumn). Therefore, it is determined in advance before the second period that temperature control of the temperature of the secondary battery 5 will not be performed during the second period (autumn).

[0050] When performing temperature control of the secondary battery 5 during the second period, the control command generation unit 17 transmits a control command to the battery control unit 8 via the transceiver unit 13 to maintain the temperature T of the secondary battery 5 within a predetermined temperature range that is equal to or higher than the lower limit temperature Tlow and equal to or lower than the upper limit temperature Tup after the end of charging of the secondary battery 5 during the second period. Then, based on the received control command, the battery control unit 8 controls the operation of the temperature regulator 7, for example, after the end of charging of the secondary battery 5 during the second period, to maintain the temperature T of the secondary battery 5 within the aforementioned predetermined temperature range. At this time, the temperature T of the secondary battery 5 is adjusted by controlling the operation of the temperature regulator 7 based on the measurement result of the temperature T of the secondary battery 5 by the measurement circuit 6, etc. Furthermore, during the second period, the aforementioned temperature control of the secondary battery 5 based on the control command from the control command generation unit 17 is continuously performed for a predetermined duration from the end of charging of the secondary battery 5.

[0051] Here, when the negative electrode is in a state where it has deteriorated to a certain extent, such as when its degree of deterioration exceeds a first reference level, charging the secondary battery 5 in a low-temperature environment causes metallic lithium to precipitate on the negative electrode of the secondary battery 5. Furthermore, during periods when the environmental temperature is low, such as winter, the internal resistance of the secondary battery 5 increases. Therefore, when the secondary battery 5 is charged, the voltage of the secondary battery 5 reaches the upper limit voltage Vmax described above within the operating range in a short time. Therefore, in low-temperature environments, sufficient measurement data cannot be obtained to estimate the internal state of the secondary battery 5 with respect to its current and voltage, making evaluation and diagnosis of the secondary battery 5 difficult. Therefore, in one example of this embodiment, based on the results of diagnosis of the secondary battery 5 in the first period (autumn), it is predicted whether metallic lithium will precipitate on the negative electrode of the secondary battery 5 due to charging in the second period (winter). If it is predicted that metallic lithium will precipitate in the secondary battery 5 due to charging under charging conditions in winter, temperature control is performed in the second period, winter, after the end of charging of the secondary battery 5 to maintain the temperature of the secondary battery 5 within a predetermined temperature range.

[0052] If metallic lithium is deposited on the negative electrode of the secondary battery 5, an oxidation reaction of the deposited metallic lithium occurs when the temperature of the secondary battery 5 rises to a certain level, for example, to 25°C or higher. The oxidation reaction of the deposited metallic lithium generates heat in the secondary battery 5. Therefore, when metallic lithium is deposited on the negative electrode due to charging of the secondary battery 5, it is necessary to suppress the occurrence of an unintended oxidation reaction of metallic lithium, from the viewpoint of suppressing an excessive temperature rise of the secondary battery 5 due to heat generated by the oxidation reaction of metallic lithium. For example, it is necessary to suppress the occurrence of an unintended oxidation reaction of metallic lithium when the secondary battery 5 is not being charged or discharged, i.e., when the secondary battery 5 is not operating. Therefore, when metallic lithium is deposited on the negative electrode due to charging of the secondary battery 5, it is necessary to intentionally oxidize the deposited metallic lithium to prevent a battery temperature rise in the secondary battery 5 due to the lithium oxidation reaction. Furthermore, even when the deposited metallic lithium is intentionally oxidized, it is necessary to appropriately adjust the temperature of the secondary battery 5 to a state in which an excessive temperature rise of the secondary battery 5 due to heat generated by the oxidation reaction of metallic lithium is suppressed.

[0053] From the above perspective, in this embodiment, if it is predicted that metallic lithium will be deposited on the secondary battery 5 due to charging during the second period, temperature control is performed to maintain the temperature T of the secondary battery 5 within the above-mentioned predetermined temperature range after the end of charging of the secondary battery 5 during the second period. Therefore, even if metallic lithium is deposited on the secondary battery 5 due to charging, the deposited metallic lithium is intentionally oxidized by temperature control of the temperature T of the secondary battery 5 performed after the end of charging. Even if metallic lithium is deposited on the secondary battery 5, the deposited metallic lithium is intentionally oxidized by temperature control. Therefore, while the secondary battery 5 is not operating until the next operation (charge or discharge), all or most of the surface of the deposited metallic lithium is oxidized and protected. Therefore, unintended oxidation reactions of metallic lithium are effectively suppressed until the next operation of the secondary battery 5.

[0054] Furthermore, the predetermined temperature range in which the temperature T of the secondary battery 5 is maintained in the temperature control performed after the end of charging is set as follows. That is, the lower limit temperature Tlow of the predetermined temperature range is set based on whether or not the temperature is at a temperature at which an oxidation reaction occurs in metallic lithium deposited in the secondary battery 5. The lower limit temperature Tlow of the predetermined temperature range is a temperature equal to or higher than the lower limit of the temperature range at which an oxidation reaction occurs in metallic lithium, and the oxidation reaction of the deposited metallic lithium occurs at the lower limit temperature Tlow of the predetermined temperature range. On the other hand, the upper limit temperature Tup of the predetermined temperature range is set based on the influence of heat generated due to an oxidation reaction of metallic lithium deposited in the secondary battery 5 on the temperature T of the secondary battery 5. The upper limit temperature Tup of the predetermined temperature range is set to a temperature at which an excessive rise in the temperature of the secondary battery 5 due to heat generated due to an oxidation reaction can be suppressed by controlling the operation of the temperature regulator 7. In one example, the lower limit temperature Tlow is set to 25°C, and the upper limit temperature Tup is set to 40°C. The predetermined temperature range is a temperature range from 25°C to 40°C.

[0055] Because the lower limit temperature Tlow is set as described above, the temperature control described above is performed after the end of charging, so that the oxidation reaction of the deposited metallic lithium occurs appropriately, and the metallic lithium is appropriately oxidized. Furthermore, because the upper limit temperature Tup is set as described above, when the temperature control described above is performed after the end of charging, the amount of heat generated due to the oxidation reaction of metallic lithium does not become excessively large, and the amount of heat generated in the secondary battery 5 due to the oxidation reaction of metallic lithium is reduced. Therefore, when the temperature control is performed, an excessive temperature rise in the secondary battery 5 due to heat generated due to the oxidation reaction of metallic lithium is appropriately suppressed.

[0056] Furthermore, in this embodiment, when the secondary battery 5 is charged in an environment where the environmental temperature is low during the second period, the temperature control described above is performed on the temperature T of the secondary battery 5 after the end of charging. Therefore, the environmental temperature of the environment in which the secondary battery 5 is charged during the period (second period) in which the temperature control is performed is lower than the environmental temperature of the environment in which the secondary battery 5 is charged during the period (first period) in which the diagnosis of the secondary battery 5 was performed before the period in which the temperature control is performed. Furthermore, the environmental temperature of the environment in which the secondary battery 5 is charged during the period (second period) in which the temperature control is performed is low enough to prevent oxidation reaction of the metallic lithium deposited on the secondary battery 5. Therefore, the lower limit temperature Tlow of the predetermined temperature range in the temperature control is higher than the environmental temperature of the environment in which the secondary battery 5 is charged during the period (second period) in which the temperature control is performed.

[0057] In one example, when temperature control is performed in the second period, the control command generator 17 and the like set at least one of the aforementioned predetermined temperature range, which is a temperature range in which the temperature T of the secondary battery 5 is maintained in the temperature control, and the aforementioned predetermined duration, which is a duration for which temperature control is continued from the end of charging, based on the degree of deterioration of the negative electrode of the secondary battery 5 in the first period, etc. In this case, for example, the higher the degree of deterioration of the negative electrode of the secondary battery 5 in the first period, the lower the predetermined temperature range for maintaining the temperature of the secondary battery 5 is set. In other words, the higher the degree of deterioration of the negative electrode of the secondary battery 5 in the first period, the lower the lower limit temperature Tlow and the upper limit temperature Tup are set. Furthermore, the higher the degree of deterioration of the negative electrode of the secondary battery 5 in the first period, the longer the duration for which temperature control is performed from the end of charging in the second period is set.

[0058] As described above, in this embodiment, if it is determined based on the diagnosis result of the secondary battery 5 during the first period that temperature control should be performed during the second period, temperature control is performed to maintain the temperature T of the secondary battery 5 within a predetermined temperature range equal to or higher than the lower limit temperature Tlow and equal to or lower than the upper limit temperature Tup for a predetermined duration from the end of charging during the second period. Furthermore, if it is determined that temperature control should be performed during the second period, the control command generator 17 may transmit a control command to the battery controller 8 to control the temperature T of the secondary battery 5 even during charging of the secondary battery 5 during the second period. In this case, if it is determined that temperature control should be performed during the second period, the temperature T of the secondary battery 5 is maintained within a predetermined temperature range equal to or higher than the lower limit temperature Tlow and equal to or lower than the upper limit temperature Tup even during charging of the secondary battery 5 during the second period. Therefore, even during charging of the secondary battery 5 during the second period, the surface of the metallic lithium deposited on the secondary battery 5 is appropriately oxidized, and an excessive temperature rise of the secondary battery 5 due to heat generated by the oxidation reaction of the metallic lithium is appropriately suppressed.

[0059] Fig. 3 is a flowchart showing an example of a diagnostic process and a determination process for a secondary battery, which are performed by a processing unit of a management device according to an embodiment. The process shown in Fig. 3 is performed periodically at a predetermined timing. However, if sufficient measurement data is not available to estimate the internal state of the secondary battery 5 with respect to the current and voltage, such as during a period when the environmental temperature in which the secondary battery 5 is used is low, the process shown in Fig. 3 is not performed. Furthermore, in this embodiment, the period during which the process of Fig. 3, including the diagnostic process for the secondary battery 5, is performed is defined as a first period.

[0060] When the process of FIG. 3 starts, the battery diagnostic unit 15 of the processing unit 11 estimates the real-time internal state of the secondary battery 5 as described above (S51). Then, the battery diagnostic unit 15 determines the real-time degree of deterioration of the negative electrode based on the result of the estimation of the internal state of the secondary battery 5 (S52). At this time, the battery diagnostic unit 15 may also determine the real-time degree of deterioration of the positive electrode based on the result of the estimation of the internal state. Then, the determination unit 16 of the processing unit 11 determines whether the real-time degree of deterioration of the negative electrode exceeds the first reference level described above (S53). If the negative electrode has deteriorated beyond the first reference level (S53-Yes), the determination unit 16 determines whether the real-time degree of deterioration of the negative electrode has exceeded the second reference level described above, which is higher than the first reference level (S54). If the negative electrode has deteriorated beyond the second reference level (S54-Yes), the control command generation unit 17 of the processing unit 11 etc. will at least one of forcibly stop the use of the secondary battery 5 and issue a warning that the use of the secondary battery 5 will be stopped (S55).

[0061] If the degree of deterioration of the negative electrode is equal to or lower than the second reference level in S54 (No in S53), the determination unit 16 acquires, as described above, the charging conditions for charging the secondary battery 5 to be performed during a second period that follows the first period during which the diagnosis is being performed (S56). Then, based on the charging conditions for charging the secondary battery 5 during the second period, the determination unit 16 predicts whether metallic lithium will precipitate on the negative electrode of the secondary battery 5 when charging under the acquired charging conditions during the second period (S57). If it is predicted that metallic lithium will precipitate during charging during the second period (Yes in S57), the determination unit 16 determines to perform temperature control to maintain the temperature T of the secondary battery 5 within the predetermined temperature range described above during the second period (S58). At this time, the processing unit 11, etc. may set at least one of a predetermined temperature range, which is a temperature range in which the temperature of the secondary battery 5 is maintained during temperature control, and a duration for which temperature control of the secondary battery 5 is continued from the end of charging, based on the judgment result regarding the degree of deterioration of the negative electrode during the first period, etc.

[0062] On the other hand, if it is predicted that metallic lithium will not be deposited in the secondary battery 5 due to charging or the like during the second period (S57-No), the determination unit 16 determines that temperature control of the temperature of the secondary battery 5 will not be performed during the second period (S59). Also, if the degree of deterioration of the negative electrode is equal to or lower than the first reference level in S53 (S53-No), the determination unit 16 determines that temperature control of the temperature of the secondary battery 5 will not be performed during the second period (S59).

[0063] Fig. 4 is a flowchart showing an example of processing related to temperature control of the temperature of the secondary battery, which is performed by the processing unit of the management device according to the embodiment. The processing shown in Fig. 4 is performed when it is determined in the processing of Fig. 3 that temperature control is to be performed to maintain the temperature T of the secondary battery 5 within a predetermined temperature range during the second period. Therefore, if it is determined in the processing of Fig. 3 that temperature control of the temperature of the secondary battery 5 is not to be performed during the second period, the processing of Fig. 4 is not performed. Furthermore, when temperature control is performed during the second period, the next charging of the secondary battery 5 is assumed to be started after a certain amount of time has elapsed since the end of the temperature control of the temperature T of the secondary battery 5.

[0064] 4 starts, the processing unit 11 etc. determines whether charging of the secondary battery 5 has started (S61). If charging has not started (S61-No), the processing returns to S61 and waits until charging starts. On the other hand, if charging has started (S61-Yes), the processing unit 11 etc. determines whether charging of the secondary battery 5 has finished (S63). If charging has not finished (S63-No), the processing returns to S63 and the processing from S63 onwards is carried out in order. Therefore, the processing waits until charging of the secondary battery 5 has finished.

[0065] Furthermore, even if charging of the secondary battery 5 has been completed (S63—Yes), the control command generation unit 17 and the like continue the temperature control to maintain the temperature T of the secondary battery 5 within the aforementioned predetermined temperature range by, for example, sending a control command to the battery control unit 8 (S64). Then, the processing unit 11 and the like determine whether a predetermined duration has elapsed since charging of the secondary battery 5 was completed (S65). If the predetermined duration has not elapsed (S65—No), the process returns to S64, and the processes from S64 onwards are sequentially performed. Therefore, the temperature control to maintain the temperature T of the secondary battery 5 within the predetermined temperature range continues. On the other hand, if the predetermined duration has elapsed (S65—Yes), the control command generation unit 17 and the like end the temperature control to maintain the temperature T of the secondary battery 5 within the predetermined temperature range (S66). After the process of S66 is performed, it is again determined in S61 whether charging of the secondary battery 5 has started.

[0066] FIG. 5 is a flowchart showing another example of the process related to temperature control of the temperature of the secondary battery, which is performed by the processing unit of the management device according to the embodiment, different from that shown in FIG. 4 . Like the process of FIG. 4 , the process shown in FIG. 5 is performed when it is determined in the process of FIG. 3 that temperature control for maintaining the temperature T of the secondary battery 5 within a predetermined temperature range is to be performed during the second period. Similarly to the process of FIG. 4 , the process of FIG. 5 also performs steps S61 and S63 to S66. However, in the example of FIG. 5 , if charging has started in S61 (Yes in S61), the control command generator 17 and the like perform temperature control for maintaining the temperature T of the secondary battery 5 within the predetermined temperature range, which is equal to or higher than the lower limit temperature Tlow and equal to or lower than the upper limit temperature Tup (S62). The process then proceeds to S63. If charging has not yet ended in S63 (No in S63), the process returns to S62, and the processes from S62 onward are sequentially performed. Therefore, the temperature control for maintaining the temperature T of the secondary battery 5 within the predetermined temperature range continues. In the example of FIG. 5, even while the secondary battery 5 is being charged, temperature control is performed to maintain the temperature T of the secondary battery 5 within the predetermined temperature range above the lower limit temperature Tlow and below the upper limit temperature Tup.

[0067] As described above, in this embodiment, whether or not metallic lithium will precipitate in the secondary battery 5 due to charging in the second period after the first period is predicted based on the diagnosis result for the secondary battery 5 in the first period and the charging conditions for charging the secondary battery 5 scheduled to be performed in the second period. Therefore, even if it is difficult to diagnose the secondary battery 5 in the second period, it is possible to predict in advance the state of the secondary battery 5 in the second period, including whether or not metallic lithium will precipitate in the secondary battery 5 due to charging, in the first period before the second period.

[0068] Furthermore, in this embodiment, if the secondary battery 5 is charged in the second period under charging conditions predicted to result in the deposition of metallic lithium in the secondary battery 5 based on the diagnosis results, etc., in the first period, temperature control is performed to maintain the temperature of the secondary battery 5 within the predetermined temperature range after the end of charging under those charging conditions. By performing temperature control in the second period, even if metallic lithium is deposited on the negative electrode during charging in the second period, the surface of the deposited metallic lithium is appropriately oxidized, as described above, effectively preventing unintended oxidation reactions of the metallic lithium. Furthermore, by performing temperature control, excessive temperature increases in the secondary battery 5 due to heat generation resulting from the oxidation reactions of the metallic lithium are appropriately prevented, as described above. Therefore, even during periods when it is difficult to diagnose the secondary battery 5, the secondary battery 5 is managed safely and appropriately based on the state of the secondary battery 5 predicted in advance.

[0069] Furthermore, in one example of the above-described embodiment, when the temperature control is performed on the temperature of the secondary battery 5 during the second period, the predetermined temperature range for maintaining the temperature of the secondary battery 5 during the temperature control is set lower as the degree of deterioration of the negative electrode during the first period increases. Here, the higher the degree of deterioration of the negative electrode of the secondary battery 5, the greater the impact on the temperature of the secondary battery 5 of heat generated by the oxidation reaction of the deposited metallic lithium. Therefore, by performing temperature control to maintain the temperature within a lower temperature range for secondary batteries with a higher degree of deterioration of the negative electrode, excessive temperature increases in the secondary battery 5 due to heat generated by the oxidation reaction of metallic lithium can be more effectively suppressed during the temperature control of the secondary battery 5.

[0070] Furthermore, in one example of the above-described embodiment, when the temperature control of the secondary battery 5 is performed during the second period, the duration of the temperature control from the end of charging is set longer as the degree of deterioration of the negative electrode during the first period increases. Here, in the temperature control of the secondary battery 5, as described above, the secondary battery 5 with a higher degree of deterioration of the negative electrode may be maintained in a lower temperature range, in order to prevent excessive temperature rise of the secondary battery 5. In this case, even if the temperature of the secondary battery 5 is maintained in a low temperature range during the temperature control, the longer the duration of the temperature control, the more appropriately the deposited metallic lithium is oxidized, and all or most of the surface of the deposited metallic lithium is oxidized by the temperature control. This more effectively prevents unintended oxidation reactions of metallic lithium from occurring until the next operation of the secondary battery 5.

[0071] In the above-described embodiments, a period when the environmental temperature of the environment in which the secondary battery 5 is used is low, such as in winter, has been cited as an example of a period during which evaluation and diagnosis of the secondary battery 5 are difficult. However, this is not limited to this. For example, if a charger normally used breaks down, the secondary battery 5 may be charged using a charger that charges at a high charge rate instead. Even when the secondary battery 5 is charged at a high charge rate, the voltage of the secondary battery 5 reaches the upper limit voltage Vmax of the operating range in a short period of time. Therefore, even during periods when the secondary battery 5 is charged at a high charge rate, sufficient measurement data cannot be obtained to estimate the internal state of the secondary battery 5 with respect to the current and voltage, making evaluation and diagnosis of the secondary battery 5 difficult.

[0072] In this case, as in the above-described embodiment, the state of the secondary battery 5, including whether metallic lithium will precipitate on the negative electrode due to charging, is predicted in advance during a first period prior to the second period, during which it is difficult to diagnose the secondary battery 5. If it is predicted that metallic lithium will precipitate on the negative electrode due to charging during the second period based on the results of the diagnosis of the secondary battery 5 performed during the first period, the temperature control described above is performed after the end of charging during the second period, maintaining the temperature of the secondary battery 5 within a predetermined temperature range. Therefore, as in the above-described embodiment, the secondary battery 5 is managed safely and appropriately based on the state of the secondary battery 5 predicted in advance, even during a period during which it is difficult to diagnose the secondary battery 5.

[0073] In at least one of the above-described embodiments or examples, when the secondary battery is charged under charging conditions predicted to cause metallic lithium to precipitate in the secondary battery based on the diagnosis results of the first period during a second period after the first period in which the secondary battery is diagnosed, temperature control of the secondary battery is performed. In the temperature control of the secondary battery, the temperature of the secondary battery after the end of charging under the above-described charging conditions during the second period is maintained within a predetermined temperature range equal to or higher than a lower limit temperature and equal to or lower than an upper limit temperature. This makes it possible to provide a secondary battery management method, management device, management system, and management program, as well as a battery-equipped device, that safely and appropriately manage the secondary battery based on a previously predicted state of the secondary battery during a period in which it is difficult to diagnose the secondary battery.

[0074] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. The following are additional notes. [1] A method for managing a secondary battery, a temperature control method for maintaining the temperature of the secondary battery within a predetermined temperature range of not less than a lower limit temperature and not more than an upper limit temperature after the end of charging under charging conditions predicted to cause metallic lithium to precipitate in the secondary battery based on the diagnosis results of the first period, when the secondary battery is charged under charging conditions predicted to cause metallic lithium to precipitate in the secondary battery based on the diagnosis results of the first period, during a second period after the first period in which the secondary battery is diagnosed. [2] The lower limit temperature of the predetermined temperature range is set based on whether or not the lower limit temperature is a temperature at which an oxidation reaction occurs in the metallic lithium deposited in the secondary battery, the upper limit temperature of the predetermined temperature range is set based on the influence of heat generated by the oxidation reaction of the metallic lithium deposited in the secondary battery on the temperature of the secondary battery. [1] The management method described above. [3] The management method according to [1] or [2], wherein the environmental temperature at which the secondary battery is charged during the second period is lower than the environmental temperature at which the secondary battery is charged during the first period. [4] The management method according to [3], wherein the lower limit temperature of the predetermined temperature range is higher than the environmental temperature at which the secondary battery is charged during the second period. [5] The management method described in any one of [1] to [4], further comprising determining whether or not to perform temperature control of the temperature of the secondary battery after the end of charging under the charging conditions during the second period, based on the estimated result of the internal state of the secondary battery in the diagnosis during the first period and the charging conditions for the secondary battery scheduled to be performed during the second period. [6] The management method described in [5], wherein the temperature control of the temperature of the secondary battery is performed after the end of the charging under the charging conditions during the second period based at least on the fact that the degree of deterioration of the negative electrode of the secondary battery based on the internal state of the secondary battery during the first period has exceeded a first reference level. [7] The management method described in [6], wherein when the temperature control is performed on the temperature of the secondary battery after the end of the charging under the charging conditions in the second period, the higher the degree of deterioration of the negative electrode of the secondary battery in the first period, the lower the specified temperature range for maintaining the temperature of the secondary battery is set, and / or the higher the degree of deterioration of the negative electrode of the secondary battery in the first period, the longer the duration of the temperature control from the end of the charging. [8] The management method described in [6] or [7], further comprising at least one of forcibly stopping use of the secondary battery and issuing a warning to stop use of the secondary battery, based on the fact that the degree of deterioration of the negative electrode of the secondary battery during the first period exceeds a second reference level that is higher than the first reference level. [9] A management device for a secondary battery, A management device comprising a processor that performs temperature control to maintain the temperature of the secondary battery within a predetermined temperature range above a lower limit temperature and below an upper limit temperature after the end of charging under charging conditions that are predicted to cause metallic lithium to precipitate in the secondary battery based on the diagnosis results of the first period during a second period after the first period in which the secondary battery is diagnosed.

[10] [9] management device; the secondary battery, the temperature of which is controlled by the processor of the management device; A management system for the secondary battery, comprising:

[11] [9] management device; the secondary battery, the temperature of which is controlled by the processor of the management device; A battery-powered device equipped with the above.

[12] A secondary battery management program, comprising: When the secondary battery is charged under charging conditions that are predicted to cause metallic lithium to precipitate in the secondary battery based on the diagnosis results of the first period during a second period after the first period during which the secondary battery is diagnosed, temperature control is performed to maintain the temperature of the secondary battery within a predetermined temperature range that is equal to or higher than a lower limit temperature and equal to or lower than an upper limit temperature after the end of charging under the charging conditions. Management program. [Explanation of symbols]

[0075] 1...management system, 2...battery-equipped device, 3...management device, 5...secondary battery, 6...measuring circuit, 7...temperature regulator, 8...battery control unit, 11...processing unit, 12...data storage unit, 13...transmitting / receiving unit, 15...battery diagnosis unit, 16...determination unit, 17...control command generation unit.

Claims

1. A method for managing a secondary battery, comprising: performing temperature control to maintain the temperature of the secondary battery within a predetermined temperature range not less than a lower limit temperature and not more than an upper limit temperature after the end of charging under charging conditions predicted to cause metallic lithium to precipitate in the secondary battery based on the diagnosis results for the first period, during a second period after the first period in which the secondary battery is diagnosed; the lower limit temperature of the predetermined temperature range is set based on whether or not the lower limit temperature is a temperature at which an oxidation reaction occurs in the metallic lithium deposited in the secondary battery; the upper limit temperature of the predetermined temperature range is set based on the influence of heat generated by the oxidation reaction of the metallic lithium deposited in the secondary battery on the temperature of the secondary battery. Management method.

2. 2. The management method according to claim 1, wherein an environmental temperature at which the secondary battery is charged during the second period is lower than an environmental temperature at which the secondary battery is charged during the first period.

3. 3. The management method according to claim 2, wherein the lower limit temperature of the predetermined temperature range is higher than the environmental temperature at which the secondary battery is charged during the second period.

4. 4. The management method according to claim 1, further comprising determining whether to perform temperature control of the temperature of the secondary battery after the end of charging under the charging conditions during the second period, based on the estimated result of the internal state of the secondary battery in the diagnosis during the first period and the charging conditions for charging the secondary battery scheduled to be performed during the second period.

5. 5. The management method according to claim 4, wherein the temperature control of the temperature of the secondary battery is performed after the end of the charging under the charging conditions during the second period based at least on the fact that the degree of deterioration of the negative electrode of the secondary battery based on the internal state of the secondary battery during the first period has exceeded a first reference level.

6. 6. The management method according to claim 5, wherein, when the temperature control is performed on the temperature of the secondary battery after the end of charging under the charging conditions during the second period, at least one of setting the predetermined temperature range for maintaining the temperature of the secondary battery lower as the degree of deterioration of the negative electrode of the secondary battery during the first period increases, and / or lengthening the duration of the temperature control from the end of charging as the degree of deterioration of the negative electrode of the secondary battery during the first period increases.

7. 7. The management method according to claim 5, further comprising at least one of forcibly stopping use of the secondary battery and issuing a warning to stop use of the secondary battery, based on the fact that the degree of deterioration of the negative electrode of the secondary battery during the first period exceeds a second reference level that is higher in degree of deterioration than the first reference level.

8. A management device for a secondary battery, a processor that performs temperature control to maintain the temperature of the secondary battery within a predetermined temperature range that is equal to or higher than a lower limit temperature and equal to or lower than an upper limit temperature after the end of charging under charging conditions that are predicted to cause metallic lithium to precipitate in the secondary battery based on the diagnosis results for a second period after a first period in which the secondary battery is diagnosed, the lower limit temperature of the predetermined temperature range is set based on whether or not the lower limit temperature is a temperature at which an oxidation reaction occurs in the metallic lithium deposited in the secondary battery; the upper limit temperature of the predetermined temperature range is set based on the influence of heat generated by the oxidation reaction of the metallic lithium deposited in the secondary battery on the temperature of the secondary battery. Management device.

9. a management device according to claim 8; the secondary battery, the temperature of which is controlled by the processor of the management device; A management system for the secondary battery, comprising:

10. a management device according to claim 8; the secondary battery, the temperature of which is controlled by the processor of the management device; A battery-powered device equipped with the above.

11. A secondary battery management program, comprising: when the secondary battery is charged under charging conditions that are predicted to cause metallic lithium to precipitate in the secondary battery based on the diagnosis results for the first period during a second period after the first period in which the secondary battery is diagnosed, temperature control is performed to maintain the temperature of the secondary battery within a predetermined temperature range that is equal to or higher than a lower limit temperature and equal to or lower than an upper limit temperature after the end of charging under the charging conditions; the lower limit temperature of the predetermined temperature range is set based on whether or not the lower limit temperature is a temperature at which an oxidation reaction occurs in the metallic lithium deposited in the secondary battery; the upper limit temperature of the predetermined temperature range is set based on the influence of heat generated by the oxidation reaction of the metallic lithium deposited in the secondary battery on the temperature of the secondary battery. Management program.

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