Determination system and determination method

Abstract

To provide a determination system capable of properly determining control conditions under which battery abnormality can be suppressed.SOLUTION: A determination system 100 comprises: a calculation part 15 which calculates spectrum information representing a spectrum on a two-axis coordinate system having relaxation times on one axis and intensities on the other axis from respective time-series data including a DC current value and at least one value of a DC voltage value or the SOC of a secondary battery 210 during charging / discharging that is at least one of charging or discharging of the secondary battery; and a determination part 16 which determines control conditions for the secondary battery 210 using shape information related to the shape of the spectrum calculated by the calculation part 15.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a decision-making system and a decision-making method. [Background technology]

[0002] In recent years, efforts have been made to use secondary batteries such as lithium-ion batteries as onboard power sources for ships, aircraft, and vehicles (railroads, automobiles, etc.), as well as for storing electricity in smart houses and smart grids, in order to utilize energy more efficiently. However, the characteristics of secondary batteries can deteriorate rapidly if used improperly. For this reason, in order to continue using products equipped with secondary batteries for long periods of time, it is preferable to set the operating conditions (control conditions) of the secondary batteries appropriately. In the following, rapid deterioration of the characteristics of secondary batteries is referred to as "battery abnormality," and battery abnormality is to be distinguished from deterioration over time that accompanies normal use.

[0003] An example of a battery abnormality is the lithium precipitation phenomenon. This is a deterioration phenomenon that occurs when a secondary battery is continuously used under conditions such as low temperature and high current value. In the lithium precipitation phenomenon, metallic lithium is precipitated on the electrodes of the secondary battery, causing a decrease in the capacity of the secondary battery and an increase in resistance. Furthermore, if the lithium precipitation phenomenon continues to progress, it may eventually cause an internal short circuit in the secondary battery.

[0004] In order to suppress battery abnormalities, studies are being conducted on analyzing the internal state of a battery. For example, the abstract of Patent Document 1 states that "the analysis device is provided with a battery state analysis unit that detects changes in the state of components of a battery based on changes in the peak of relaxation time in a specified frequency band." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2017 / 179266 Summary of the Invention [Problem to be solved by the invention]

[0006] FIG. 17 is a schematic diagram for explaining the respective thresholds of temperature and current value at which a battery abnormality occurs. In order to reduce the frequency of replacement and repair of the secondary battery due to the battery abnormality, it is preferable to specify the conditions under which the battery abnormality occurs and to control the battery so as to avoid using the secondary battery under those conditions. For example, in order to suppress the occurrence of the lithium deposition phenomenon, it is sufficient to specify the respective thresholds of temperature and current value at which the lithium deposition phenomenon occurs in advance. Specifically, for example, in FIG. 17, a function f representing the thresholds is determined, for example, by an experiment, a simulation, or the like. Then, by avoiding use in the region S above the graph of the function f, the lithium deposition phenomenon can be suppressed. That is, it is preferable to control the temperature, current value, and the like of the secondary battery so as to avoid the region S.

[0007] There are two main methods known for identifying conditions under which abnormalities occur in secondary batteries. One method involves using a secondary battery continuously for a long period of time at a constant temperature and current value, causing it to deteriorate, and determining whether or not a battery abnormality occurs during that process. This method is called a cycle degradation test, and by conducting the cycle degradation test under multiple temperature and current value conditions, it is possible to identify conditions under which battery abnormalities occur. However, there is an issue that identifying conditions under which abnormalities occur using cycle degradation tests requires a test period of several months to several years, making it difficult to use this method to detect and address the risk of abnormalities occurring in secondary batteries at an early stage.

[0008] The other method is to measure the reaction current value (hereinafter referred to as the reaction mode) flowing through the secondary battery. If a secondary battery is used under conditions that cause battery abnormalities, the number of reaction modes measured during the charge and discharge process of the secondary battery changes. For example, in the case of lithium deposition reduction, in addition to the mode of lithium ion insertion reaction into the electrode (normal battery reaction), a reaction mode in which lithium ions are deposited on the electrode surface occurs inside the secondary battery. Therefore, the number of reaction modes increases compared to normal charge and discharge reactions. In other words, by focusing on the change in the number of reaction modes, it is possible to determine whether or not a battery abnormality will occur under the usage conditions of the secondary battery. Since the measurement of the number of reaction modes can be completed in a test of about several minutes, it has the advantage of being able to quickly determine the risk of abnormality occurrence compared to cycle deterioration tests.

[0009] As a technique for measuring the number of reaction modes, the AC impedance method described in paragraph 0064 of Patent Document 1 uses an AC current value. However, a high AC current cannot be applied to a secondary battery. On the other hand, battery abnormalities are prominent in secondary batteries, particularly when a large current is passed through them. Therefore, the AC impedance method using AC current cannot properly evaluate battery abnormalities in secondary batteries, and cannot properly determine control conditions capable of suppressing battery abnormalities.

[0010] The problem to be solved by the present disclosure is to provide a determination system and a determination method capable of appropriately determining control conditions capable of suppressing battery abnormalities. [Means for solving the problem]

[0011] The determination system of the present disclosure includes a calculation unit that calculates spectrum information representing a spectrum in a two-axis coordinate system with one axis representing relaxation time and the other axis representing intensity from each time series data including at least one of a DC current value and a DC voltage value or a SOC of the secondary battery during charging or discharging, which is at least one of charging and discharging of the secondary battery, and a determination unit that determines a control condition of the secondary battery using shape information regarding the shape of the spectrum calculated by the calculation unit. Other solutions will be described later in the description of the embodiment of the invention. Effect of the Invention

[0012] According to the present disclosure, it is possible to provide a determination system and a determination method capable of appropriately determining control conditions that can suppress battery abnormalities. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a block diagram illustrating a decision system of the present disclosure. [Diagram 2] 11 is a map showing calculation results of a relaxation spectrum for each temperature and each current value. [Diagram 3] 11 is a map showing calculation results of a relaxation spectrum for each temperature and each voltage value in another embodiment. [Figure 4] 11 is a map showing calculation results of a relaxation spectrum for each voltage value and each current value in another embodiment. [Diagram 5] FIG. 13 is a diagram illustrating an example of a relaxation spectrum. [Figure 6] FIG. 1 is a block diagram illustrating a decision system according to another embodiment. [Figure 7] FIG. 1 is a block diagram illustrating a decision system according to another embodiment. [Figure 8] FIG. 1 is a block diagram illustrating a decision system according to another embodiment. [Figure 9] FIG. 2 is a block diagram showing a hardware configuration of the determination system. [Figure 10] 1 is a flowchart illustrating a determination method of the present disclosure. [Figure 11] This is a map showing conditions for generating a battery abnormality determined from a relaxation spectrum, which was obtained by actually carrying out an evaluation test. [Figure 12] This map was obtained by actually conducting an evaluation test, and excludes the range in which battery abnormalities occur. [Figure 13] 1 is a photograph showing the electrode surface of a secondary battery used under Condition 1 (Example). [Figure 14] 1 is a photograph showing the electrode surface of a secondary battery used under Condition 2 (Comparative Example). [Figure 15]1 shows verification results showing the difference in battery capacity between a secondary battery used under condition 1 (Example) and a secondary battery used under condition 2 (Comparative Example). [Figure 16] 1 shows verification results showing the difference in internal resistance between a secondary battery used under condition 1 (Example) and a secondary battery used under condition 2 (Comparative Example). [Figure 17] 5A and 5B are schematic diagrams illustrating thresholds of temperature and current values ​​at which a battery abnormality occurs. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, a form for carrying out the present disclosure (referred to as an embodiment) will be described with reference to the drawings. In the following description of one embodiment, other embodiments applicable to the one embodiment will also be described as appropriate. The present disclosure is not limited to the following one embodiment, and different embodiments can be combined with each other or modified as desired without significantly impairing the effects of the present disclosure. In addition, the same symbols will be used for the same members, and duplicate descriptions will be omitted. Furthermore, the same names will be used for members having the same functions. The contents shown are merely schematic, and for the sake of illustration, changes may be made from the actual configuration within a range that does not significantly impair the effects of the present disclosure, and some members may be omitted or modified between drawings. In addition, the same embodiment does not necessarily need to have all the configurations.

[0015] FIG. 1 is a block diagram showing a determination system 100 of the present disclosure. Hereinafter, the determination system 100 and the secondary battery 210 are collectively referred to as a battery system 300. Thus, the battery system 300 includes the determination system 100 and the secondary battery 210. The determination system 100 determines control conditions (charge / discharge conditions) of the secondary battery 210 that suppress the occurrence of a battery abnormality in the secondary battery 210. As described above, the battery abnormality is an abnormality that is different from deterioration over time that accompanies normal use, and is, for example, a lithium deposition phenomenon on the electrode surface, but is not limited thereto.

[0016] A power consumption device 400, such as a motor or an inverter, and a power source 500 are connected to the secondary battery 210. The power source 500 charges the secondary battery 210. The power consumption device 400 is driven by power generated by discharging the secondary battery 210. Therefore, at least one of the charging and discharging (preferably both, hereinafter collectively referred to as charging and discharging) is performed in accordance with the control conditions determined by the determination system 100.

[0017] The control conditions of the secondary battery 210 include, for example, at least one of a DC current value during charging / discharging, a DC voltage value during charging / discharging, or the temperature of the secondary battery 210. Hereinafter, unless otherwise specified, the DC current value, the DC voltage value, and the temperature of the secondary battery will be simply referred to as a current value, a voltage value, and a temperature, etc., as appropriate. The secondary battery 210 is, for example, a lithium ion secondary battery, but may be, for example, another type of secondary battery, such as a lead storage battery or a nickel cadmium battery.

[0018] The determination system 100 includes a measurement unit 11, a recording unit 12, an assignment unit 13, a classification unit 14, a calculation unit 15, a determination unit 16, and a control unit 17. These may all be configured integrally, or at least some of them may be configured separately. When these are all configured integrally, the determination system 100 can be called a determination device. On the other hand, when at least some of them are configured separately, for example, the part may be stored in a server (not shown) installed in a remote location, for example, via a network.

[0019] The measurement unit 11 measures time series data of each value including a DC current value and at least one of a DC voltage value and the SOC of the secondary battery 210 during charging or discharging, which is at least one of charging and discharging of the secondary battery 210. That is, the time series data includes time series data of a DC current value and j-series data of at least one of a DC voltage value and the SOC of the secondary battery 210. The measurement is performed constantly or at a predetermined time interval (for example, every minute) during use, including during charging or discharging of the secondary battery 210 and during standby when charging or discharging is not performed. Since there is a correlation between the DC voltage value and the SOC, in the following, as an example, the measurement unit 11 measures time series data related to the DC voltage value. However, the measurement unit 11 may measure time series data of the SOC. In addition, in the example of the present disclosure, the time series data further includes time series data of the temperature of the secondary battery 210.

[0020] The measuring unit 11 extracts time series data from a collection of measured time series data (so-called "raw data") in a period (timing) during which a relaxation spectrum can be calculated. The relaxation spectrum is a continuous function of relaxation time, and is a spectrum (charge / discharge spectrum) in a two-axis coordinate system with one axis (e.g., horizontal axis) representing relaxation time and the other axis (e.g., vertical axis) representing intensity (spectral intensity). For example, it is preferable to extract each time series data in at least one of the periods during constant voltage charging, after charging, or after discharging. After charging may be after constant voltage charging or after constant current charging. After discharging may be after constant voltage discharging or after constant current discharging. It is also preferable that there are a plurality of time series data extracted from different periods.

[0021] When extracting time series data during constant voltage charging, the measurement unit 11 extracts time series data on the voltage value, current value, and temperature of the secondary battery 210 from time t1 when constant voltage charging starts to time t2 when constant voltage charging ends. "Constant voltage charging" is a charging method in which the secondary battery 210 is charged while being maintained at a constant voltage value. Furthermore, the measurement unit 11 also extracts the voltage value before (preferably immediately before) the start of charging the secondary battery 210. There is no limit to the time from time t1 to time t2, but it is preferably 1 minute or more and 30 minutes or less, and more preferably 10 minutes or more and 20 minutes or less.

[0022] When extracting time series data after charging (after charging is completed) or after discharging (after discharging is completed), the measurement unit 11 extracts time series data of the voltage value, current value, and temperature of the secondary battery 210 from the charging or discharging end time t3 to a predetermined time t4. Furthermore, the measurement unit 11 also obtains the current value immediately before the charging or discharging of the secondary battery 210 is completed. There is no limit to the time from time t3 to time t4, but it is preferably 1 minute or more and 30 minutes or less, and more preferably 10 minutes or more and 20 minutes or less.

[0023] There is no limitation on the method by which the measurement unit 11 acquires the measurement data (data including the above-mentioned time-series data, the voltage value before the start of charging, the current value immediately before charging / discharging, etc.) from the secondary battery 210. For example, the measurement unit 11 can measure data (e.g., measurement data) related to the secondary battery 210 at a location different from the location where the secondary battery 210 is installed. This allows, for example, when the secondary battery 210 is installed in a vehicle, ship, aircraft, etc., the measurement data, for example, of the secondary battery 210 to be centrally managed by, for example, a server (not shown) located at a remote location. This can improve convenience.

[0024] Specifically, for example, the measurement unit 11 may acquire the measurement data from the secondary battery 210 via a communication circuit such as an electric circuit or a wired LAN, may acquire the measurement data from the secondary battery 210 placed in a remote location via a network such as a wireless LAN, or may acquire the measurement data by a combination of these methods. In addition, in the process in which the measurement unit 11 acquires the measurement data from the secondary battery 210, the measurement unit 11 may acquire the measurement data via some other device. For example, the measurement unit 11 may acquire the measurement data from the secondary battery 210 via an external device (not shown) such as a charging / discharging device. In addition, the measurement unit 11 may store the measurement data acquired from the secondary battery 210 on a server (not shown), and the measurement unit 11 may acquire the measurement data.

[0025] The recording unit 12 stores the measurement data of the secondary battery 210 extracted by the measuring unit 11 (data including the above-mentioned time series data, the voltage value before the start of charging, the current value immediately before charging and discharging, etc.). It is preferable that these measurement data are classified and stored according to the timing at which the corresponding data was extracted. For example, measurement data D extracted between time tA and time tB is AB and measurement data D extracted between time tC and time tD. CD If there exists measurement data D AB ,D CD are preferably not lumped together, but are linked to the period during which they were acquired (for example, from time tA to time tB, from time tC to time tD, etc.) and stored individually in the recording unit 12.

[0026] The assigning unit 13 assigns a heading to each spectrum calculated from the time series data acquired between different times according to a predetermined rule using at least two of a direct current value, a direct current voltage value, and a temperature. By providing the assigning unit 13, a map (described later) including a plurality of relaxation spectra can be created from the time series data acquired based on various times and types (current value, voltage value, or temperature).

[0027] In the example of the present disclosure, the assigning unit 13 refers to the measurement data stored in the recording unit 12 and calculates representative values ​​(examples of headings) of the current value, the voltage value, and the temperature. The calculated representative values ​​are assigned to the calculated relaxation spectrum and the measurement data used to calculate the relaxation spectrum. As will be described in detail later, the relaxation spectrum is calculated based on time-series data measured in different periods. Then, the calculated relaxation spectrum and the representative values ​​are associated with each other.

[0028] When a plurality of measurement data extracted at different time timings are stored in the recording unit 12, the assigning unit 13 calculates a representative value for each measurement data. AB and measurement data D extracted between time tC and time tD. CD If there is, the attachment unit 13 adds the measurement data D AB,D CD A representative value is calculated for each period.

[0029] There are no particular limitations on the method of calculating the representative value (method of determining the heading) as long as the calculation can be performed according to the same predetermined rules regardless of the type and period of time-series data. Two examples of the method of calculating the representative value are shown below.

[0030] <Method 1 of calculating representative values: Calculating representative values ​​from measurement data during constant voltage charging> For example, the representative current value may be the current value immediately after the start of constant-voltage charging, the representative voltage value may be the average voltage value during constant-voltage charging, and the representative temperature value may be the average value of the time-series data of the measured temperature.

[0031] <Method 2 of calculating representative values: Calculating representative values ​​from measurement data after charging or discharging> For example, the representative current value may be the current value immediately before the end of charging or immediately before the end of discharging, the representative voltage value may be the voltage value immediately before the end of charging or immediately after the end of discharging, and the representative temperature value may be the average value of the recorded time series data of temperature.

[0032] The classification unit 14 classifies the relaxation spectrum with the given heading so that the relaxation spectrum is associated with at least two conditions of a current value (DC current value), a voltage value (DC voltage value), or a temperature according to the given heading. By providing the classification unit 14, a map (described later) including a plurality of relaxation spectra can be created from time series data acquired based on various times and types. The specific contents of the map will be described later with reference to, for example, FIG. 2.

[0033] Each of the conditions here includes a numerical range, and therefore the relaxation spectrum is associated with any of a plurality of numerical ranges constituting each of at least two of the conditions, for example, a current range, a voltage range, or a temperature range.

[0034] In the example of the present disclosure, the classification unit 14 classifies each measurement data accumulated in the recording unit 12 using the control conditions (usage conditions) assumed when using the secondary battery 210 and the representative value assigned by the assignment unit 13. The control conditions include the respective usage ranges of the current value, voltage value, and temperature assumed when, for example, charging and discharging the secondary battery 210. The control conditions can be determined in advance based on, for example, the intended use of the secondary battery 210.

[0035] As a specific classification method, for example, the classification unit 14 divides the control conditions of the secondary battery 210 into a finite number of sections. min ~T max If it is expected to be used in min <T max ), the classification unit 14 is min ~T1, T1~T2, T2~T3,...,T N-1 ~T max The classification unit 14 divides the expected range of use of the secondary battery 210 into N intervals such that N is an integer equal to or greater than 1. Similarly, for the current and voltage values ​​of the secondary battery 210, the classification unit 14 divides the expected range of use into a finite number of sections in a similar manner. The use conditions of the secondary battery 210 may be registered in advance in the calculation unit 15 (described later), or may be determined based on measurement data of the secondary battery 210 acquired by the measurement unit 11. When the determination is based on measurement data, for example, the minimum value of a collection of measured time-series data (raw data), for example, for temperature, may be set to T min , the maximum value is T max can be set to.

[0036] Next, the classification unit 14 selects which of the above-mentioned categories corresponds to the representative value assigned to the time series data by the assignment unit 13. In this way, the time series data stored in the recording unit 12 is classified into each category. If the recording unit 12 stores a plurality of time series data extracted at different times as described above, classification is performed for each of the time series data.

[0037] If multiple data measured at different time timings are assigned to the same section as a result of classification, the classification unit 14 processes the time series data so that the number of time series data for each of the current value, voltage value, and temperature is determined to be one. In this way, one numerical range is associated with one relaxation spectrum. The numerical range here is a numerical range included in at least two conditions of the current value, voltage value, and temperature, as described above. For example, in the case of temperature, the temperature range is T min ~T1, T1~T2, T2~T3,...,T N-1 ~T max Either:

[0038] As a processing method, for example, only the most recently acquired data can be used. Also, the result of taking the average of all data assigned to the same division can be used. Specifically, for example, when there are multiple pieces of time series data of current values, the time series data of the average current value can be created by taking the average of all the time series data of current values.

[0039] The calculation unit 15 calculates spectral information representing the relaxation spectrum (an example of a spectrum). The spectral information may be a graph representing the relaxation spectrum, a function representing the relaxation spectrum, or the shape of the relaxation spectrum. The shape may include at least one of the number of peaks included in the relaxation spectrum, the position of the peak, the area of ​​the peak, the half-width of the peak, or the skewness of the peak, for example. The spectral information may be character information (e.g., numerical values) or information other than character information (e.g., shape).

[0040] The calculation unit 15 calculates the relaxation spectrum from each time series data in at least one of the periods during constant voltage charging, after charging, and after discharging. The relaxation spectrum can be calculated by using these time series data. A specific calculation method is as follows, but the calculation method is not limited to the following example.

[0041] <Calculation method 1: Calculating the relaxation spectrum from measurement data during constant voltage charging> In this case, the relaxation spectrum ρ(τ) can be calculated from the measurement data using equation (1).

[0042]

number

[0043] ρ(τ) indicates the relaxation spectrum, ΔV indicates the difference between the battery voltage value before (preferably immediately before) the start of charging and the voltage value during constant voltage charging, and I(t) indicates the time series data of the current value during constant voltage charging. -1 (the reciprocal of a capital L in cursive) denotes the inverse Laplace transform of I(t) / ΔV.

[0044] <Calculation method 2: Calculating the relaxation spectrum from measurement data after charging or discharging> In this case, the relaxation spectrum ρ(τ) can be calculated from the following equation (2) using the measurement data.

number

[0045] ρ(τ) indicates the relaxation spectrum, I0 indicates the current value immediately before the end of charging or discharging, and V(t) indicates the time series data of the voltage value after charging or discharging. -1 (the inverse of the capital letter L in cursive) denotes the inverse Laplace transform of V(t) / I0.

[0046] Fig. 2 is a map showing the calculation results of the relaxation spectrum for each temperature and each current value. Fig. 2 shows, as an example, an example in which the temperature is divided into T1-T2, T2-T3, and T3-T4 (each of which is a numerical range), and the current value is divided into I1-I2, I2-I3, and I3-I4 (each of which is a numerical range). In addition, in the nine relaxation spectra shown in Fig. 2, the horizontal axis represents the relaxation time, and the vertical axis represents the intensity of the spectrum, although this is omitted for the sake of simplicity. The same applies to Figs. 3, 4, 11, and 12 described below.

[0047] As described above, the calculation unit 15 (FIG. 1) calculates a relaxation spectrum for each section using the time series data, etc., classified by the classification unit 14 (FIG. 1) into each section of temperature and current value. Therefore, for example, as a result of classification, a relaxation spectrum calculated using the time series data, etc., classified into temperatures T1-T2 and current values ​​I1-I2 is classified (stored) into the items of temperatures T1-T2 and current values ​​I1-I2. Then, by classifying each relaxation spectrum into each item using each time series data, etc., a map (relaxation spectrum map) such as that shown in FIG. 2 can be obtained.

[0048] The mitigation spectrum is associated with the temperature of the secondary battery 210, for example, as shown in FIG. 2. The current value and voltage value capable of suppressing the occurrence of a battery abnormality may differ depending on the temperature of the secondary battery 210. That is, even if the current value and voltage value are the same, the likelihood of a battery abnormality occurring may differ if the temperature of the secondary battery 210 differs. Thus, by determining the control conditions taking into consideration the temperature of the secondary battery 210, the battery abnormality of the secondary battery 210 can be suppressed more effectively. Note that, for example, depending on the installation environment of the secondary battery 210, the temperature of the secondary battery 210 may be predictable to some extent. In addition, the secondary battery 210 may be used at a temperature or for an application where a battery abnormality is unlikely to occur in the first place. Therefore, in these cases, the temperature may not be taken into consideration.

[0049] Moreover, the relaxed spectrum classified into each category is preferably based on time series data measured in different periods. The period referred to here is a period whose starting point is reset every time the secondary battery 210 is replaced, repaired, or the like. In Fig. 2, the relaxed spectrum 200 preferably includes, for example, a first relaxed spectrum 221 calculated from time series data from a first time to a second time, and a second relaxed spectrum 222 calculated from time series data from a third time to a fourth time. By including a plurality of relaxed spectra 200, it is possible to determine a control condition under which a battery abnormality occurs based on a change in the shape of the relaxed spectrum, as will be described in detail later.

[0050] Fig. 3 is a map showing calculation results of relaxation spectra for each temperature and each voltage value in another embodiment. Fig. 3 shows an example in which temperatures are divided into T1-T2, T2-T3, and T3-T4 (each of which is a numerical range), and voltage values ​​are divided into V1-V2, V2-V3, and V3-V4 (each of which is a numerical range).

[0051] 3, the first range R1 is the temperature range of T1 to T4 and the voltage range of V1 to V3. Meanwhile, the second range R2 is the temperature range of T1 to T4 and the voltage range of V3 to V4. The half width of the peak of the second relaxation spectrum 222 included in the second range R2 is larger than the half width of the peak of the first relaxation spectrum 221 included in the first range R1.

[0052] As described above, the time series data of the present disclosure relates to current values ​​(FIG. 2), voltage values, and temperature. Therefore, while FIG. 2 shows a map relating to two of these, current values ​​and temperature, the map is not limited to current values ​​and temperatures, and may be a map relating to voltage values ​​and temperatures shown in FIG. 3. The map of FIG. 3 can be created in the same manner as the embodiment of FIG. 2, except that time series data relating to voltage values ​​is used instead of current values.

[0053] Fig. 4 is a map showing calculation results of relaxation spectra for each voltage value and each current value in another embodiment. Fig. 4 shows, as an example, an example in which the voltage values ​​are divided into V1 to V2, V2 to V3, and V3 to V4 (each of which is a numerical range), and the temperatures are divided into T1 to T2, T2 to T3, and T3 to T4 (each of which is a numerical range).

[0054] 4, the first range R1 includes voltage values ​​V1 to T3 and current values ​​I1 to I3. Meanwhile, the second range R2 includes voltage values ​​V3 to V4 and current values ​​I1 to I4, and voltage values ​​V1 to V4 and current values ​​I3 to I4. The half-width of the peak of the second relaxation spectrum 222 included in the voltage values ​​V3 to V4 and current values ​​I1 to I4 (second range R2) is larger than the half-width of the peak of the first relaxation spectrum 221 included in the first range R1. In addition, the number of peaks of the second relaxation spectrum 222 included in the voltage values ​​V1 to V4 and current values ​​I3 to I4 (second range R2) is larger than the number of peaks of the first relaxation spectrum 221 included in the first range R1.

[0055] As described above, the time series data of the present disclosure relates to current values, voltage values, and temperature (FIG. 2). Therefore, the map is not limited to the examples of FIG. 2 and FIG. 3, and may be a map relating to voltage values ​​and current values ​​shown in FIG. 4. The map of FIG. 4 can be created in the same manner as the embodiment of FIG. 2, except that time series data relating to voltage values ​​is used instead of temperature.

[0056] In the example of the present disclosure, for example, three maps shown in Figs. 2 to 4 can be constructed based on time-series data of current values, voltage values, and temperature. By using the three maps, more accurate control conditions can be determined. In particular, different control conditions may be determined between the maps due to the influence of measurement errors and the like. In this case, for example, the condition that places the smallest load on the secondary battery 210 (for example, the lowest current value and voltage value in the case of current values ​​and voltage values) or a control condition that is common between the maps may be adopted as the control condition.

[0057] 1, the determination unit 16 determines the control conditions of the secondary battery 210 by using the shape information on the shape of the relaxed spectrum calculated by the calculation unit 15. The determined control conditions are, as described above, control conditions for the secondary battery 210 that can suppress the occurrence of a battery abnormality in the secondary battery 210, such as a current value, a voltage value, and a temperature during charging and discharging.

[0058] Fig. 5 is a diagram showing an example of a relaxation spectrum 200. The relaxation spectrum 200 shown in Fig. 5 has two peaks 201 and 202. The positions of the peaks 201 and 202 are relaxation times τ1 and τ2. The areas of the peaks 201 and 202 are S1 and S2. The half-widths of the peaks 201 and 202 are W1 and W2. The skewnesses of the peaks 201 and 202 are K1 and K2.

[0059] The shape information used by the determination unit 16 preferably includes a quantifiable index. Specifically, for example, the shape information preferably includes at least one of the number of peaks 201, 202 in the relaxation spectrum 200, the positions of the peaks 201, 202, the areas of the peaks 201, 202, the half-widths of the peaks 201, 202, or the skewness of the peaks 201, 202. Since these are all quantifiable indexes, the possibility of abnormal deterioration occurring can be determined with an objective index when determining a battery abnormality, as described in detail later.

[0060] The determination unit 16 (FIG. 1) will be further described with reference to FIG. 2. Focusing on the number of peaks of the nine relaxation spectra shown in FIG. 2, in the second range R2 satisfying the temperatures T1 to T3 and the current values ​​I3 to I4, the number of peaks is three, unlike the number of peaks (two) in the first range R1, which is the other range. That is, when viewed from the first range R1 other than the second range R2 satisfying the temperatures T1 to T3 and the current values ​​I3 to I4, the number of peaks increases from the first range R1 to the second range R2. The first range is the range of temperatures T1 to T4 and current values ​​I1 to I3, and the range of temperatures T3 to T4 and current values ​​I3 to I4.

[0061] As described above, the shape information of the relaxed spectrum corresponds to the occurrence of a reaction mode inside the secondary battery 210. Therefore, a change in the shape of the relaxed spectrum (e.g., an increase in the number of peaks, etc.) suggests the occurrence of a mobile reaction mode. Therefore, the determination unit 16 determines the control conditions based on a change in the shape from the first relaxed spectrum 221 classified into the first range R1 to the second relaxed spectrum 222. This makes it possible to determine the control conditions under which a battery abnormality occurs, and therefore to determine the control conditions capable of suppressing the occurrence of a battery abnormality.

[0062] As described above, the number of peaks 201 and 202 in the relaxation spectrum 200, the positions of the peaks 201 and 202, the areas of the peaks 201 and 202, the full width at half maximum of the peaks 201 and 202, and the skewness of the peaks 201 and 202 are all quantifiable indices. Therefore, if the shape of the relaxation spectrum changes, the changes in these indices can be expressed as a numerical "change amount".

[0063] Then, when the shape of the relaxation spectrum changes such that an index such as the number of peaks changes in the positive direction, for example, the determination unit 16 determines that a battery abnormality has occurred in the secondary battery 210. For example, when the index is the number of peaks, as described above, the number of peaks changes from 2 (first range R1) to 3 (second range R2) in the positive direction (+1). Therefore, the determination unit 16 determines that a battery abnormality has occurred at the temperature and current value in the second range R. Also, in the case of the position of the peak, although not shown in the figure, in the relaxation spectra of the first range R1 and the second range R2, if the relaxation time indicating the position of the corresponding peak changes from, for example, τ1 to τ2 (τ1 < τ2), it can be said that the relaxation time has changed in the positive direction.

[0064] In the case where the index is the area of the peak, although not shown in the figure, in the relaxation spectra of the first range R1 and the second range R2, if the area of the corresponding peak changes from, for example, S1 to S2 (S1 < S2), it can be said that the area has changed in the positive direction. The area of the peak can be calculated according to any method. In the case where the index is the full width at half maximum of the peak, although not shown in the figure, in the relaxation spectra of the first range R1 and the second range R2, if the full width at half maximum of the corresponding peak changes from, for example, W1 to W2 (W1 < W2), it can be said that the full width at half maximum has changed in the positive direction. The full width at half maximum of the peak can be calculated according to any method. In the case where the index is the skewness of the peak, although not shown in the figure, in the relaxation spectra of the first range R1 and the second range R2, if the skewness of the corresponding peak changes from, for example, K1 to K2 (K1 < K2), it can be said that the skewness has changed in the positive direction. The skewness of the peak can be calculated according to any method.

[0065] As shown in FIG. 12 described later, for example, even if the area, half-width, skewness, etc. change in a positive direction (i.e., increase), it may be determined that no potential abnormality occurs. Therefore, a threshold value for the amount of change may be determined in advance for each quantifiable index, and it may be determined that a battery abnormality occurs when an amount of change exceeds the threshold value. Such a threshold value may be determined, for example, by experiments, simulations, trial runs, etc. Also, in order to improve the accuracy of the determination, a plurality of indexes may be used for the determination.

[0066] Then, the determination unit 16 determines the control conditions so as to exclude the changes that are determined to cause a battery abnormality in the secondary battery 210. To explain this in detail with reference to Fig. 2, the determination unit 16 determines that a battery abnormality will occur in, for example, a second range R2 in the map shown in Fig. 2 where the number of peaks, etc., is greater than in the first range R1, i.e., where the number of peaks changes in the performance direction. As a result, the determination unit 16 determines that the conditions for causing a battery abnormality in the secondary battery 210 are the temperature and current values ​​corresponding to the second range R2. In this way, the secondary battery 210 can be controlled while avoiding the occurrence of a battery abnormality.

[0067] Furthermore, the determination unit 16 determines, as the control conditions, a current value less than the abnormal current value, a voltage value less than the abnormal voltage value, and a temperature less than the abnormal temperature, which correspond to the mitigation spectrum for which it is determined that a battery abnormality will occur in the secondary battery 210. This makes it possible to suppress the occurrence of a battery abnormality.

[0068] The control unit 17 controls the charging and discharging of the secondary battery 210 in accordance with the determined control conditions for the secondary battery 210. This makes it possible to effectively suppress battery abnormalities in the secondary battery 210. In the example of the present disclosure, the control unit 17 controls the charging and discharging of the secondary battery 210 so as to suppress the frequency of use of the secondary battery 210 within the conditions for occurrence of battery abnormalities (second range R2 (FIG. 2)) set by the determination unit 16. The charging and discharging control is performed by controlling the current value, voltage value, and temperature. Note that the control unit 17 does not completely reject use in the second range R2 as long as the use in the second range R2 can be suppressed more than when the determination system 100 of the present disclosure is not used. Note that the temperature control of the secondary battery 210 can use a cooling mechanism such as an air-cooling device such as a fan or a liquid-cooling device.

[0069] The secondary battery 210 to which the present disclosure is applicable includes any form such as a secondary battery cell, a secondary battery module, a secondary battery pack, a secondary battery system, etc. The secondary battery 210 may be mounted on electric mobility such as a ship, an airplane, or a vehicle (a battery train, an electric vehicle, etc.), may be mounted on a stationary storage battery system, or may be changed in use. For example, the present disclosure may be applicable to a case where a secondary battery 210 used in an electric mobility is reused as a stationary storage battery system.

[0070] Furthermore, the present disclosure can be applied regardless of the deterioration state of the secondary battery 210. For example, the secondary battery 210 may be a new battery (undegraded), or a battery that has been used for some purpose and is in a deteriorated state (e.g., used, second-hand). Also, the secondary battery 210 may be a secondary battery that has deteriorated over time as a result of not being used for a long period of time.

[0071] Furthermore, in addition to the use of suppressing the occurrence of battery abnormalities in the secondary battery 210, the present disclosure can also be applied to control for extending the life of the secondary battery 210 during use, suppressing deterioration, and the like.

[0072] The present disclosure can also be used to determine what applications a new secondary battery 210 and a used secondary battery 210 are suitable for. The method of determination is described below.

[0073] First, the secondary battery 210 is connected to a charge / discharge device (not shown), and the secondary battery 210 is charged / discharged under preset control conditions of current value, voltage value, and temperature. Using the time-series data at this time, the relaxation spectrum is calculated by the above-mentioned method. Then, using the calculated relaxation spectrum, control conditions including at least two of the current value, voltage value, and temperature that do not cause a battery abnormality are determined.

[0074] Next, it is evaluated what current value, voltage value, and temperature the secondary battery 210 will be used at in the intended use of the secondary battery 210. For example, in the case of an electric vehicle, the current value and voltage value of the secondary battery 210 used for running the vehicle are obtained based on the motor and inverter performance, and the temperature of the secondary battery 210 is predicted from the Joule heat generated at that time. In this way, it is evaluated whether or not the current value, voltage value, and temperature obtained from the expected use of the secondary battery 210 fall within the current value, voltage value, and conditions obtained from the relaxation spectrum. This makes it possible to determine whether or not the secondary battery 210 is suitable for the expected use.

[0075] Furthermore, the determination system 100 may determine the control conditions at any time. For example, the control conditions can be determined when a product equipped with the secondary battery 210 is shipped from a factory, when the product is maintained, etc. Then, subsequent control can be performed according to the determined control conditions.

[0076] Also, for example, when the determination system 100 and the secondary battery 210 are constantly connected via a network, the determination system 100 disposed in a remote location may constantly monitor the state of the secondary battery 210 and determine the control conditions, for example, at predetermined intervals. Then, each time the control conditions are determined, the next and subsequent control operations can be performed under the determined control conditions.

[0077] Fig. 6 is a block diagram showing a determination system 100 according to another embodiment. A secondary battery 210 to be controlled by the determination system 100 shown in Fig. 6 includes a plurality of unit secondary batteries 211 connected to each other. The unit secondary battery 211 is, for example, a battery cell, a battery module, a battery pack, a battery system, etc., and is a battery module in the illustrated example. Note that, in the example of Fig. 6, a plurality of unit secondary batteries 211 are connected to one determination system 100, but one determination system 100 may be connected to each unit secondary battery 211.

[0078] 6, the control unit 17 (FIG. 1) performs different control for each unit secondary battery 211. Therefore, the secondary batteries 210 may all be unit secondary batteries 211 (e.g., new batteries) having roughly the same characteristics, but it is preferable that at least some of them include deteriorated unit secondary batteries 211 (an example of a secondary battery, e.g., a used secondary battery). Depending on the operation of the battery system 300, new unit secondary batteries 211 and deteriorated unit secondary batteries 211 may be used together. Even in such a case, by performing different control for each unit secondary battery 211, battery abnormalities in each unit secondary battery 211 can be suppressed.

[0079] First, by the method described above with reference to Figures 1 to 5, control conditions for suppressing the occurrence of battery abnormalities are determined for each unit secondary battery 211. That is, in the determination system 100 shown in Figure 6, the calculation unit 15 calculates spectrum information for each unit secondary battery 211. The determination unit 16 determines the control conditions for each unit secondary battery 211. The determined control conditions are recorded in the recording unit 12 for each unit secondary battery 211.

[0080] When multiple unit secondary batteries 211 are connected to each other, the degree of deterioration of each unit secondary battery 211 may vary due to charging and discharging of the entire secondary battery 210. For this reason, the current value, voltage value, and temperature that do not cause a battery abnormality may differ for each unit secondary battery 211. Therefore, the determination unit 16 determines control conditions that suppress the occurrence of battery abnormality for each unit secondary battery 211, and determines control conditions that do not cause battery abnormality in all unit secondary batteries 211. This makes it possible to suppress the occurrence of battery abnormality in each unit secondary battery 211.

[0081] As described above, the secondary battery 210 is connected to the power consuming device 400 (FIG. 1), such as a motor or an inverter. The current value, voltage value, and temperature used by the power consuming device 400 are expected to some extent depending on the application of the power consuming device 400. Therefore, the determination unit 16 determines for each unit secondary battery 211 whether the current value, voltage value, and temperature planned to be used by the power consuming device 400 are within the range of the control condition determined for each unit secondary battery 211. If the determination result shows that at least one of the current value, voltage value, and temperature planned to be used (planned to be supplied) deviates from the determined control condition, the determination unit 16 restricts the deviating current value, voltage value, and temperature to fall within the range of the determined control condition. The restriction can be performed, for example, so that the current value, voltage value, and temperature planned to be supplied for each unit secondary battery 211 become the upper limit value of each range of the determined control condition. In addition, the restriction may be performed so that the control conditions of all the unit secondary batteries 211 become a common control condition. After the above-mentioned determination and appropriate restriction are performed for each of the unit secondary batteries 211, power is supplied from the secondary battery 210 to the power consuming device 400.

[0082] Although discharging to the power consuming device 400 has been described here, charging from the power source 500 may also be judged and appropriately restricted in a similar manner.

[0083] Fig. 7 is a block diagram showing a determination system 100 according to another embodiment. A secondary battery 210 to be controlled by the determination system 100 shown in Fig. 7 includes a plurality of unit secondary batteries 211 connected to each other, similar to Fig. 6 above.

[0084] 1, the determination system 100 shown in Fig. 7 further includes an update unit 18. The update unit 18 determines the control conditions again for each unit secondary battery 211 by the determination unit 16 when at least one of the current value, the current value, or the temperature changes during charge / discharge control of the secondary battery 210 by the control unit 17, and updates the determined control conditions as the control conditions by the control unit 17. By including the update unit 18, it is possible to suppress battery abnormalities in the unit secondary battery 211 even when the state of the unit secondary battery 211 changes during actual operation.

[0085] The update unit 18 may, for example, constantly monitor at least one of the current value, the current value, and the temperature, or may monitor at a predetermined time (for example, every minute).

[0086] FIG. 8 is a block diagram showing a determination system 100 according to another embodiment. The determination system 100 shown in FIG. 8 further includes an output unit 19 in the determination system 100 shown in FIG. 1. The output unit 19 outputs a determination result by the determination system 100 to an external device 600. The output determination result may be, for example, the determined control condition, or may be, for example, the map described with reference to FIG. 2, or may be at least a part of the relaxation spectrum of a plurality of relaxation spectra included in the map. The output determination result may also be information such as a graph obtained by converting the determination result by the determination system 100 (for example, the determined control condition) into the form of a graph described with reference to FIG. 17, or a function.

[0087] The external device 600 may be, for example, a display device (display, monitor, etc.), an external storage device such as a HDD, or an external linked device that is provided independently of the determination system 100 and operates in cooperation with the determination system 100.

[0088] 9 is a block diagram showing a hardware configuration of the determination system 100. The determination system 100 is configured to include, for example, a CPU (Central Processing Unit) 1001, a RAM (Random Access Memory) 1002, a ROM (Read Only Memory) 1003, an I / F (Interface) 1004, a bus 1005, and the like. The CPU 1001, the RAM 1002, the ROM 1003, and the I / F 1004 are connected via, for example, the bus 1005. The determination system 100 is realized by a predetermined control program (for example, the determination method of the present disclosure) stored in the ROM 1003 being expanded in the RAM 1002 and executed by the CPU 1001. Signals and information are exchanged between the determination system 100 and various devices (such as servers), an external network, and the like, in terms of hardware, through the I / F 1004.

[0089] Fig. 10 is a flowchart showing the determination method of the present disclosure. The determination method of the present disclosure can be executed, for example, by the determination system 100 shown in Fig. 1. Therefore, the matters described for the determination system 100 can be similarly applied to the determination method of the present disclosure.

[0090] The determination method of the present disclosure includes a measuring step S11, a recording step S12, an assigning step S13, a classifying step S14, a calculating step S15, a determining step S16, and a controlling step S17.

[0091] The measuring unit 11 measures time series data of each value including a DC current value and at least one of a DC voltage value and the SOC of the secondary battery 210 during charging or discharging, which is at least one of charging and discharging of the secondary battery 210. The measuring step S11 can be executed by, for example, the measuring unit 11 (FIG. 1). The recording step S12 is a step of saving the measurement data of the secondary battery 210 extracted in the measuring step S11 (data including the above-mentioned time series data, the voltage value before the start of charging, the current value immediately before charging or discharging, etc.). The recording step S12 can be executed by, for example, the recording unit 12 (FIG. 1).

[0092] The assigning step S13 is a step of assigning a heading to each spectrum calculated from time series data acquired between different times according to a predetermined rule using at least two of a DC current value, a DC voltage value, or a temperature. The assigning step S13 can be executed by, for example, the assigning unit 13 (FIG. 1). The classification step S14 is a step of classifying the relaxed spectrum to which the heading has been assigned so that the spectrum is associated with at least two conditions of a current value (DC current value), a voltage value (DC voltage value), or a temperature according to the assigned heading. The classification step S14 can be executed by, for example, the classification unit 14 (FIG. 1).

[0093] The calculation step S15 is a step of calculating spectrum information representing the relaxation spectrum (an example of a spectrum). The calculation step S15 can be executed by, for example, the calculation unit 15 (FIG. 1). The determination step S16 is a step of determining a control condition for the secondary battery 210 using shape information on the shape of the relaxation spectrum calculated in the calculation step S15. The determination step S16 can be executed by, for example, the determination unit 16 (FIG. 1).

[0094] The control step S17 is a step of controlling the charging and discharging of the secondary battery 210 in accordance with the control conditions of the secondary battery 210 determined in the determination step S16. The control step S17 can be executed by, for example, the control unit 17 (FIG. 1). EXAMPLES

[0095] The present disclosure will now be described more specifically with reference to examples.

[0096] An evaluation test was actually performed on the identification of the conditions under which a battery abnormality occurs using the determination system 100 and the control of the secondary battery 210 using the determination system 100.

[0097] For verification, a cylindrical lithium-ion secondary battery (an example of the secondary battery 210) with a battery capacity of 5 Ah was used. The positive electrode (electrode 50 described later) was formed by applying LiNiMnCoO2 as a positive electrode active material to a metal current collector, and the negative electrode was made of carbon. For the measurement data for calculating the relaxation spectrum, time-series data of each value of the current value, voltage value, and temperature during the use of the secondary battery 210 were used. Furthermore, a plurality of time-series data during constant voltage charging were extracted, and from the extracted time-series data, representative values of the current value and temperature and the relaxation spectrum were calculated.

[0098] The representative values of the current value were divided into sections of 0 A to 25 A, 25 to 50 A, 50 to 75 A, 75 A to 100 A, and 100 A to 125 A. The representative values of the temperature were divided into sections of 0 to 10 °C, 10 °C to 25 °C, 25 °C to 35 °C, and 35 °C to 45 °C. Then, the representative values were classified along these sections.

[0099] Subsequently, using the time-series data classified into each section, the relaxation spectrum was calculated for each. At this time, when a plurality of time-series data acquired at different time timings were included in each section, the relaxation spectrum was calculated using the time-series data acquired at the latest time timing. For example, when two types of time-series data acquired at time tA to time tB and time tC to time tD were included in the section specified by a current value of 0 A to 25 A and a temperature of 0 °C to 10 °C (where tB < tC), the relaxation spectrum was calculated using the time-series data acquired at time tC to time tD.

[0100] FIG. 11 is a map obtained by actually conducting an evaluation test to determine the occurrence conditions of battery abnormalities from the relaxation spectrum. In the map shown in FIG. 11, paying attention to the shape information of the obtained relaxation spectrum, the occurrence conditions of battery abnormalities were specified. Here, the number of peaks was used as the shape information of the relaxation spectrum. The reason for this is that, as described above, the shape information of the relaxation spectrum corresponds to the reaction mode inside the battery, and in particular, an increase in the number of peaks on the relaxation spectrum indicates the occurrence of an abnormal reaction mode inside the battery.

[0101] FIG. 12 is a map obtained by actually carrying out an evaluation test, excluding the range where a battery abnormality occurs. The shaded range is the second range R2, and the non-shaded range is the first range R1. The relaxation spectrum in the second range R2 is present in the following sections: temperature 0°C to 10°C and current value 50A to 125A, temperature 10°C to 25°C and current value 75A to 125A, and temperature 25°C to 35°C and current value 100A to 125A. The relaxation spectrum in the first range R1 is present in the following sections: temperature 0°C to 10°C and current value 0A to 50A, temperature 10°C to 25°C and current value 0A to 75A, temperature 25°C to 35°C and current value 0A to 100A, and temperature 35°C to 45°C and current value 0A to 125A.

[0102] Comparing the relaxation spectrum in the shaded second range R2 with the relaxation spectrum in the unshaded first range R1, the shaded relaxation spectrum has two peaks, whereas the unshaded relaxation spectrum has one peak. Therefore, the shaded second range R2 of the relaxation spectrum suggests the occurrence of an abnormal reaction mode inside the battery. For this reason, it is considered that the occurrence of battery abnormalities can be suppressed by controlling the current value and temperature of the secondary battery 210 so as to avoid using the secondary battery 210 as much as possible under the temperature and current value conditions corresponding to the shaded first range R1.

[0103] Furthermore, in order to verify the effects of the present disclosure, it was verified whether or not a battery abnormality occurs in a case where control is performed to avoid use under the temperature and current value conditions corresponding to the shaded relaxation spectrum in Fig. 9 (Condition 1, Example) and a case where control is performed to continue using the secondary battery mainly under the temperature and current value conditions (Condition 2, Comparative Example). In the verification, the secondary battery 210 that had been used continuously for about four months under Conditions 1 and 2 was disassembled, and it was investigated whether or not an abnormality occurred on the electrodes of the secondary battery 210.

[0104] Fig. 13 is a photograph of the surface of electrode 50 of secondary battery 210 (Fig. 1) used under condition 1 (example). As shown in Fig. 13, the surface of electrode 50 had a uniform appearance, and no abnormalities were found on the surface of electrode 50.

[0105] Fig. 14 is a photograph of the surface of the electrode 50 of the secondary battery 210 (Fig. 1) used under condition 2 (comparative example). As shown in Fig. 14, a band-like deposition region 51 where lithium deposition abnormality occurred was confirmed on the surface of the electrode 50. Therefore, it was confirmed that the determination system 100 of the present disclosure can suppress the occurrence of battery abnormalities.

[0106] As another comparative example, a method using the AC impedance method described in Patent Document 1 was also performed. However, it was impossible to measure the time series data of the current value and voltage value of the secondary battery 210. The reason for this is that in order to obtain the results shown in Figures 11 and 12, a large current of up to about 100 A is applied to the secondary battery 210, but the voltage value reaches an overvoltage value when the AC current value is applied, and therefore cannot be measured. In this way, the results shown in Figures 11 and 12 can only be obtained by using DC current values ​​and DC voltage values, and it can be seen that the present disclosure is more significant than the invention described in Patent Document 1.

[0107] Next, as another evaluation, the effectiveness of the present disclosure as a control method for suppressing deterioration of the secondary battery 210 and enabling the secondary battery 210 to be used for a long life was verified. In the verification, the secondary battery 210 was used according to the conditions 1 and 2 determined in Fig. 11 and Fig. 12 above, and the deterioration state after use was compared. Specifically, after about four months of use, the extent to which the battery capacity and internal resistance of each secondary battery 210 had deteriorated from when it was new was measured.

[0108] Fig. 15 is a verification result showing the difference in battery capacity between the secondary battery 210 used under condition 1 (Example) and the secondary battery 210 used under condition 2 (Comparative Example). Fig. 15 and Fig. 16 described later show relative values ​​when the battery capacity and internal resistance of a new (undegraded) secondary battery 210 are set at 100%. In Fig. 15 and Fig. 16 described later, the numerical values ​​written above the bar graphs are the numerical values ​​used as the basis for creating the bar graphs written below the numerical values. In Fig. 15, the vertical axis shows the capacity maintenance rate (%).

[0109] 15, under condition 1 (Example), the battery capacity only decreased slightly (95.6%) even after about four months of use. On the other hand, under condition 2 (Comparative Example), the battery capacity decreased significantly after about four months of use, and the battery capacity decreased to about 75% (75.1%) of the battery capacity of a new secondary battery 210. Thus, it was found that the decrease in battery capacity due to deterioration of the secondary battery 210 can be suppressed by controlling under condition 1.

[0110] Fig. 16 shows the results of verification showing the difference in internal resistance between the secondary battery 210 used under condition 1 (example) and the secondary battery 210 used under condition 2 (comparative example). In Fig. 16, the vertical axis represents the resistance maintenance rate (%).

[0111] 16, under condition 1 (Example), the internal resistance only increased slightly (107.4%) even after about four months of use. On the other hand, under condition 2 (Comparative Example), the internal resistance increased significantly after about four months of use, and the internal resistance increased to about 1.9 times (187.1%) that of a brand new secondary battery 210. Thus, it was found that the increase in internal resistance due to deterioration of the secondary battery 210 can be suppressed by controlling under condition 1.

[0112] 15 and 16, by using the determination system 100, it is possible to perform charging and discharging in such a way as to avoid a significant decrease in battery capacity and a significant increase in internal resistance. As a result, the present disclosure is effective in suppressing deterioration of the secondary battery 210, and the life of the secondary battery 210 can be extended. [Explanation of symbols]

[0113] 100 Decision System 11 Measurement section 12 Recording section 13 Granting Department 14 Classification section 15 Calculation section 16 Decision Section 17 Control Unit 18 Update section 200 Relaxation Spectrum 201 Peak 202 Peak 210 Secondary battery 211 Unit secondary battery 300 Battery System S11 Measurement step S12 Recording Step S13 Granting step S14 Classification step S15 Calculation step S16 Decision Step S17 Control step

Claims

1. a calculation unit that calculates spectral information representing a spectrum in a two-axis coordinate system, one axis representing relaxation time and the other axis representing intensity, from time series data of each value including at least one of a DC current value and a DC voltage value or an SOC of the secondary battery during charging or discharging, which is at least one of charging and discharging of the secondary battery; a determination unit that determines a control condition for the secondary battery using shape information regarding the shape of the spectrum calculated by the calculation unit. A decision system comprising:

2. The shape information includes at least one of the number of peaks in the spectrum, the positions of the peaks, the areas of the peaks, the half-widths of the peaks, or the skewness of the peaks. The determination system of claim 1 .

3. The calculation unit calculates the spectrum from the time series data in at least one of a period during constant voltage charging, a period after charging, and a period after discharging. The determination system of claim 1 .

4. the time-series data includes time-series data of the temperature of the secondary battery, The spectrum is correlated with the temperature of the secondary battery. The determination system of claim 1 .

5. an assigning unit that assigns a label to each spectrum calculated from time-series data acquired between different times in accordance with a predetermined rule using at least two of a DC current value, a DC voltage value, and a temperature; a classification unit that classifies the spectra with the given headings so that the spectra are associated with at least two conditions of a DC current value, a DC voltage value, or a temperature, according to the given headings. The determination system of claim 1 .

6. Each of the conditions includes a plurality of numerical ranges, One of the numerical ranges is associated with one of the spectra. The determination system of claim 5 .

7. the spectrum includes a first relaxation spectrum calculated from time series data from a first time to a second time, and a second relaxation spectrum calculated from time series data from a third time to a fourth time, The determination unit determines the control condition based on a change in shape from the first relaxation spectrum to the second relaxation spectrum. The determination system of claim 5 .

8. The shape information regarding the shape includes a quantifiable index, The determination unit determining that a battery abnormality has occurred in the secondary battery when the shape changes so that the indicator changes in a positive direction; The control conditions are determined so as to exclude any change determined to cause a battery abnormality in the secondary battery. The determination system of claim 7 .

9. The determination unit determines, as the control condition, a DC current value less than an abnormal DC current value, a DC voltage value less than an abnormal DC voltage value, or a temperature value less than an abnormal temperature, which corresponds to a spectrum that is determined to cause a battery abnormality in the secondary battery. The determination system of claim 7 .

10. The secondary battery includes a deteriorated secondary battery. The determination system of claim 1 .

11. The secondary battery includes a plurality of unit secondary batteries connected to each other. The determination system of claim 1 .

12. the calculation unit calculates the spectral information for each of the unit secondary batteries; The determination unit determines the control condition for each of the unit secondary batteries. The decision system of claim 11 .

13. a control unit that controls charging and discharging of the secondary battery in accordance with the determined control conditions for the secondary battery; an updating unit that, when at least one of a DC current value, a DC voltage value, and a temperature changes during charge / discharge control of the secondary battery by the control unit, determines the control condition again for each unit secondary battery by the determination unit, and updates the determined control condition as the control condition by the control unit. The decision system of claim 11 .

14. a measuring unit that measures data related to the secondary battery at a location different from the location where the secondary battery is installed; The determination system of claim 1 .

15. a calculation step of calculating spectral information representing a spectrum in a two-axis coordinate system, one axis representing relaxation time and the other axis representing intensity, from time series data of each value including at least one of a DC current value and a DC voltage value or an SOC of the secondary battery during charging or discharging, which is at least one of charging and discharging of the secondary battery; a determining step of determining a control condition for the secondary battery using shape information regarding the shape of the spectrum calculated in the calculating step. A method for determining whether a

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