Deterioration degree determination device for secondary battery

Abstract

The degradation degree determination device (1) includes a battery information acquisition unit (61), a validity determination unit (62), a battery characteristic acquisition unit (63), and a degradation degree determination unit (65). The battery information acquisition unit (61) acquires battery information related to the secondary batteries (21-26). The validity determination unit (62) determines whether the degradation degree determination is valid for each secondary battery (21-26) based on the battery information acquired by the battery information acquisition unit (61) and a pre-prepared validity determination criteria. The battery characteristic acquisition unit (63) acquires battery characteristics related to the progression of battery state within a specified voltage range for the secondary batteries (21-26) that are determined by the validity determination unit (62) to be eligible for degradation degree determination. The degradation degree determination unit (65) determines the degradation degree of the secondary batteries (21-26) that are determined to be eligible for degradation degree determination based on the battery characteristics acquired by the battery characteristic acquisition unit (63) or battery characteristic related values ​​calculated based on the battery characteristics.

Description

[0001] Cross-reference of related applications

[0002] This application is based on Japanese Patent Application No. 2020-113170, filed on June 30, 2020, the contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to a device for determining the degree of degradation of a secondary battery. Background Technology

[0004] Previously, battery packs composed of multiple secondary battery modules were widely used. However, these secondary battery modules degrade with use, but the degree of degradation varies for each individual module. Therefore, even if the degradation of some secondary batteries within a battery pack exceeds a certain threshold, the entire battery pack becomes unusable. In such cases, the usual practice is to remove usable secondary batteries with lower degradation from the battery pack and reuse them. Patent Document 1 discloses a structure for detecting the degradation degree of secondary battery modules in a battery pack. Specifically, after discharging the battery pack's state of charge (SOC) to below the lower limit of its normal operating range, each secondary battery module is removed, and its remaining capacity is measured. Then, the capacity difference between the secondary battery modules is calculated and compared to a threshold. If the capacity difference is above a predetermined value, the remaining lifespan of the secondary battery module with the smaller capacity is considered to be below a predetermined value, and the degradation degree of each secondary battery module is determined accordingly.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Re-evaluation No. 2012 / 137456

[0008] In the structure disclosed in Patent Document 1, when the difference in degradation degree among the secondary battery modules included in the battery pack is small, it is not possible to derive the remaining life, i.e., the degradation degree, with high accuracy. For example, when the degradation degree of all the secondary battery modules included in the battery pack is high or low, it is difficult to generate a difference in degradation degree, so the detection accuracy of degradation degree is poor. On the other hand, in order to remove the secondary battery modules from the battery pack and determine the degradation degree of each of them with high accuracy, the structure can easily become complicated. Summary of the Invention

[0009] This invention provides a device for determining the degradation degree of a secondary battery with a simple structure and high precision.

[0010] One aspect of the present invention is a degradation degree determination device for a secondary battery, which is a degradation degree determination device for determining the degradation degree of a secondary battery, wherein it comprises:

[0011] A battery information acquisition unit acquires battery information related to the secondary battery.

[0012] The yes / no determination unit determines the degree of degradation of each secondary battery based on the battery information acquired by the battery information acquisition unit and a pre-prepared yes / no determination criterion.

[0013] A battery characteristic acquisition unit acquires battery characteristics related to the progression of battery state within a specified voltage range for a secondary battery that is determined by the applicability determination unit to be suitable for a degree of degradation; and

[0014] The degradation degree determination unit determines the degradation degree of the secondary battery that is determined to be capable of degradation degree determination based on the battery characteristics acquired by the battery characteristic acquisition unit or the battery characteristic related value calculated based on the battery characteristics.

[0015] In the aforementioned degradation degree determination apparatus, the degradation degree of the secondary battery is determined based on battery characteristics related to voltage shifts within a predetermined voltage range obtained from the secondary battery, or based on relevant values ​​of these battery characteristics. Therefore, degradation degree determination can be performed with a simple procedure. Furthermore, by setting a voltage range that shows a high correlation between the voltage shift of the secondary battery and the degradation degree, the degradation degree of the secondary battery can be determined with high accuracy, even before determining the degradation degree of the secondary battery. Then, after determining whether each secondary battery is suitable for degradation degree determination, the degradation degree of the secondary battery is determined for those batteries deemed suitable for degradation degree determination. Therefore, by determining the degradation degree of secondary batteries that sufficiently ensure determination accuracy, the overall determination accuracy can be improved.

[0016] As described above, according to one aspect of the present invention, a degradation degree determination device for a secondary battery can be provided, which can accurately determine the degree of degradation with a simple structure.

[0017] Furthermore, the symbols in parentheses within the scope of the claim indicate a correspondence with the specific units described in the embodiments described later, and are not intended to limit the technical scope of the present invention. Attached Figure Description

[0018] The above and other objects, features, and advantages of the present invention will become more apparent from the accompanying drawings and from the following detailed description. These drawings are as follows:

[0019] Figure 1 This is a conceptual diagram showing the structure of the degradation determination device in Implementation 1.

[0020] Figure 2 These are conceptual diagrams showing the structure of the battery pack in Embodiment 1 and a conceptual diagram of a vehicle equipped with the battery pack.

[0021] Figure 3 This is a conceptual diagram illustrating the battery characteristics in Implementation Method 1.

[0022] Figure 4 This is a conceptual diagram representing the validity determination criteria in Implementation 1.

[0023] Figure 5 This is a flowchart illustrating the method for determining the degree of degradation of the secondary battery in Implementation Method 1.

[0024] Figure 6 This is a flowchart illustrating the manufacturing method of the battery pack in Embodiment 1.

[0025] Figure 7 This is a conceptual diagram representing the battery characteristics in variation mode 1.

[0026] Figure 8 This is a conceptual diagram representing the battery characteristics in variant mode 2.

[0027] Figure 9 This is a conceptual diagram representing the battery characteristics in variation mode 3.

[0028] Figure 10 This is a conceptual diagram illustrating the battery characteristics in Implementation Method 4.

[0029] Figure 11 This is a conceptual diagram representing the battery characteristics in variation mode 5.

[0030] Figure 12 This is a flowchart illustrating the method for determining the degree of degradation of the secondary battery in Embodiment 2.

[0031] Figure 13 This is a flowchart illustrating the method for determining the degree of degradation of the secondary battery in deformation mode 6.

[0032] Figure 14 This is a flowchart illustrating the method for determining the degree of degradation of the secondary battery in Embodiment 3.

[0033] Figure 15 This is a conceptual diagram showing the structure of the degradation determination device in Implementation 4.

[0034] Figure 16 This is a flowchart illustrating the method for determining the degree of degradation of the secondary battery in Embodiment 4.

[0035] Figure 17 This is a conceptual diagram showing the structure of the degradation determination device in Implementation 5.

[0036] Figure 18 This is a conceptual diagram showing the structure of the degradation determination device in Implementation 6.

[0037] Figure 19 This is a conceptual diagram illustrating the battery characteristics in Implementation Method 6.

[0038] Figure 20 This is a conceptual diagram representing the structure of the degradation determination device in deformation mode 7.

[0039] Figure 21 This is a conceptual diagram showing the structure of the degradation determination device in Implementation 7.

[0040] Figure 22 This is a conceptual diagram illustrating the battery characteristics in Implementation Method 7.

[0041] Figure 23 This is a conceptual diagram representing the battery characteristics in variant 8.

[0042] Figure 24 This is a conceptual diagram illustrating the battery characteristics in Implementation Method 9.

[0043] Figure 25 This is a conceptual diagram representing the SOC-OCV curve of the secondary battery in Implementation Method 8.

[0044] Figure 26 This is a flowchart illustrating the method for determining the degree of degradation of the secondary battery in Embodiment 8.

[0045] Figure 27 (a) is a conceptual diagram showing the discharge curve of the secondary battery in embodiment 8. Figure 27 (b) is a conceptual diagram showing the charging curve of the secondary battery in embodiment 8.

[0046] Figure 28 This is a flowchart illustrating the method for determining the degree of degradation of the secondary battery in Embodiment 9.

[0047] Figure 29 This is a conceptual diagram representing the SOC-OCV curve of the secondary battery in Embodiment 10.

[0048] Figure 30 This is a flowchart illustrating the method for determining the degree of degradation of the secondary battery in Embodiment 11.

[0049] Figure 31 (a) is a conceptual diagram showing the discharge curve of the secondary battery in embodiment 11. Figure 31 (b) is a conceptual diagram representing another discharge curve of the secondary battery in embodiment 11.

[0050] Figure 32 This is a conceptual diagram representing an example of the presumed result in Implementation 12.

[0051] Figure 33 This is a conceptual diagram showing the structure of the degradation determination device in Implementation 13.

[0052] Figure 34 This is a flowchart illustrating the method for determining the degree of degradation of the secondary battery in Embodiment 13. Detailed Implementation

[0053] (Implementation Method 1)

[0054] use Figures 1 to 6 The implementation method of the above-mentioned secondary battery degradation determination device will be described.

[0055] like Figure 1 As shown, the degradation degree determination device 1 of this embodiment 1 determines the degradation degree of secondary batteries 21 to 26, and has a battery information acquisition unit 61, a pass / fail determination unit 62, a battery characteristic acquisition unit 63, and a degradation degree determination unit 65.

[0056] The battery information acquisition unit 61 acquires battery information about secondary batteries 21 to 26.

[0057] The approval determination unit 62 determines whether the degradation degree of each secondary battery 21 to 26 can be determined based on the battery information acquired by the battery information acquisition unit 61 and the pre-prepared approval determination criteria.

[0058] The battery characteristic acquisition unit 63 acquires battery characteristics related to the progression of battery state within a specified voltage range for secondary batteries 21 to 26 that are determined by the approval / disapproval unit 62 to be suitable for a degree of degradation assessment.

[0059] The degradation determination unit 65 determines the degradation degree of the secondary batteries 21 to 26 that are determined to be eligible for degradation determination based on the battery characteristics acquired by the battery characteristic acquisition unit 63 or based on the battery characteristic correlation value calculated based on the battery characteristics.

[0060] The following is a detailed description of the secondary battery degradation determination device 1 of Embodiment 1.

[0061] exist Figure 1 In the degradation degree determination device 1 shown, the type of secondary batteries 21 to 26 that are the objects of degradation degree determination is not limited, and known secondary batteries such as nickel-metal hydride batteries and lithium-ion secondary batteries can be used. The secondary battery may also have one or more individual cells. In this embodiment 1, as... Figure 2As shown in (a), secondary batteries 21 to 26 constitute secondary battery modules in battery pack 20 that can be individually installed and removed. While the number of secondary batteries in battery pack 20 is not particularly limited, in this embodiment 1, there are six, and secondary batteries 21 to 26 are connected in series. Alternatively, secondary batteries 21 to 26 may be connected in parallel. Furthermore, as... Figure 2 As shown in (b), the battery pack 20 is mounted as a battery in the vehicle 100.

[0062] like Figure 1 As shown, the degradation determination device 1 includes a detection unit 3, a storage unit 4, a storage unit 5, a calculation unit 6, a control unit 7, and an update unit 8.

[0063] The detection unit 3 includes a voltage detection unit 31 and a current detection unit 32. The voltage detection unit 31 is composed of a predetermined voltmeter and detects the voltage value of the secondary batteries 21 to 26. The current detection unit 32 is composed of a predetermined ammeter and detects the current value flowing through the secondary batteries 21 to 26. Furthermore, it is configured to obtain the open-circuit voltage of the secondary batteries 21 to 26 based on the voltage value detected by the voltage detection unit 31.

[0064] Figure 1 The storage unit 4 shown is composed of a rewritable non-volatile memory and includes a voltage value storage unit 41 and a current value storage unit 42. The voltage value storage unit 41 stores the voltage value detected by the voltage value detection unit 31, and the current value storage unit 42 stores the current value detected by the current value detection unit 32.

[0065] Figure 1 The storage unit 5 shown is composed of non-volatile memory and includes a correspondence storage unit 51 and a reference value storage unit 52. The correspondence storage unit 51 stores the correspondence between battery characteristics and total capacity. The form of this correspondence is not particularly limited and can be, for example, a calculation formula, a mapping, a graph, or a table. This correspondence can be generated using machine learning with a secondary battery for testing, based on measured values ​​obtained from accelerated degradation tests using a secondary battery for testing, or by logically deriving a calculation formula for the correspondence between battery characteristics and total capacity within a specified voltage range using a model of the secondary battery. Furthermore, the correspondence stored in the correspondence storage unit 51 is appropriately set according to the battery characteristics acquired by the battery characteristic acquisition unit 63, which will be described later.

[0066] The total capacity can be set as the capacity from a fully discharged state to a fully charged state during charging. Alternatively, the total capacity can also be set as the capacity from a fully charged state to a fully discharged state during discharging. Here, the term "fully discharged state" can refer to an effective fully discharged state defined by the system of the vehicle or similar device equipped with the secondary battery 2, or it can refer to a state that has reached the lower limit voltage set by the user using the degradation degree assessment device 1. Similarly, the term "fully charged state" can refer to an effective fully charged state defined by the system of the vehicle or similar device, or it can refer to a state that has reached the upper limit voltage set by the user.

[0067] In addition, Figure 1 The reference value storage unit 52 shown contains pre-stored approval reference values ​​for determining the degree of degradation used in the approval / disapproval unit 62 (described later) and degradation reference values ​​for determining the degree of degradation used in the degradation determination unit 65 (described later). These two reference values ​​are appropriately set according to the determination methods in the approval / disapproval unit 62 and the degradation determination unit 65, respectively. In this embodiment 1, multiple degradation reference values ​​are set in a manner that allows for the determination of degradation in five levels.

[0068] Figure 1 The control unit 7 shown includes a charge / discharge control unit 71. The charge / discharge control unit 71 controls the charging and discharging of the secondary battery 2. The charge / discharge control unit 71 is composed of a computing device capable of executing a predetermined program.

[0069] Figure 1 The arithmetic unit 6 shown is composed of a defined arithmetic device and includes a battery information acquisition unit 61, a feasibility determination unit 62, a battery characteristic acquisition unit 63, a capacity estimation unit 64 as an estimation unit, and a degradation degree determination unit 65. The battery information acquisition unit 61 acquires battery information as information related to the secondary batteries 21-26. This battery information may be historical information of the secondary batteries 21-26, or it may be used in place of this information, or it may be used simultaneously as the battery characteristics described later. In this embodiment 1, the battery information acquisition unit 61 uses the battery characteristics acquired by the battery characteristic acquisition unit 63 (described later) as battery information.

[0070] Figure 1The approval / disapproval determination unit 62, as shown, determines the approval / disapproval of the degradation degree determination for each secondary battery 21-26 based on the battery information acquired by the battery information acquisition unit 61 or the battery information related value calculated from the battery information and the approval / disapproval determination benchmark stored in the benchmark value storage unit 52. In this embodiment 1, the approval / disapproval determination unit 62 determines the approval / disapproval of the degradation degree determination for each secondary battery 21-26 based on the battery information related value calculated from the battery information acquired by the battery information acquisition unit 61 and the approval / disapproval determination benchmark. The secondary batteries that are determined not to be eligible for degradation degree determination are batteries outside the area of ​​training data used when defining the degradation degree determination benchmark in the degradation degree determination unit 65 described later, and are batteries in the unlearned area. Therefore, for these secondary batteries, there is a possibility that the determination accuracy cannot be sufficiently guaranteed in this degradation degree determination, and therefore the degradation degree determination described later is not performed. Thus, by determining the degradation degree of secondary batteries for which the determination accuracy can be sufficiently guaranteed, the overall determination accuracy can be improved. Furthermore, for secondary batteries whose degradation was not assessed in this degradation assessment, the total capacity is measured separately by the update unit 8 (described later), and this measurement can be used as training data to define the assessment criteria for subsequent degradation assessments. Therefore, since the assessment criteria can be updated based on the changes in the secondary battery over time, high assessment accuracy can be maintained.

[0071] The validity / disappearance determination criteria used in the validity / disappearance determination unit 62 can be generated by using machine learning of the secondary battery used for testing, based on experimentally measured values ​​obtained from accelerated degradation tests using the secondary battery used for testing, or by logically deriving the relational formula for the validity / disappearance determination criteria using a model of the secondary battery. Furthermore, the validity / disappearance determination criteria can be expressed as upper and lower limits, only the upper limit, only the lower limit, or a mapped form. For example, as... Figure 4 As shown, the correspondence between battery information A and battery information B obtained from the secondary battery used for measurement is used as training data. A specified range calculated through machine learning can be set as the criterion for acceptance or rejection. That is, the distance between data points in this training data can be set as the criterion for acceptance or rejection. This distance between data points can be defined based on Mahalanobis distance, Euclidean distance, Manhattan distance, Chebyshev distance, etc.

[0072] In this embodiment 1, the approval / disapproval determination unit 62 is configured to determine approval / disapproval based on Mahalanobis distance. This Mahalanobis distance is calculated by comparing a battery information correlation value with the aforementioned approval / disapproval determination criteria. The battery information correlation value is calculated from the battery information obtained by the battery information acquisition unit using a pre-set relational formula related to multiple battery information values. Furthermore, multiple approval / disapproval criteria can be set. That is, after determining the approval / disapproval of a first degree of degradation based on a first approval / disapproval determination criterion, a second degree of degradation determination can be performed on a secondary battery that is determined not to be eligible for the first degree of degradation based on a second approval / disapproval criterion.

[0073] The battery characteristic acquisition unit 63 acquires the battery characteristics of secondary batteries 21-26 within a predetermined voltage range. The battery characteristics of secondary batteries 21-26 can be, for example, defined as characteristics based on voltage and temperature changes of secondary battery 2 within a predetermined voltage range Vs. Furthermore, this voltage change can be calculated based on at least one of, for example, the range capacity of secondary batteries 21-26 within the predetermined voltage range, the ratio of voltage change of secondary batteries 21-26 within the predetermined voltage range to capacity change of secondary battery 2, and the ratio of voltage change of secondary batteries 21-26 within the predetermined voltage range to the elapsed time. The predetermined voltage range can be defined as a voltage range that expresses the relationship between the degradation degree and battery state changes of secondary batteries 21-26. Such a voltage range can be set based on the type and structure of secondary batteries 21-26, or derived using machine learning of secondary batteries. Additionally, the battery characteristic acquisition unit 63 can also acquire the absolute value of the acquired values ​​as battery characteristics. The specified voltage range Vs of the battery characteristics of the secondary batteries 21 to 26 can be set relative to each secondary battery 21 to 26, or can be appropriately changed.

[0074] In this embodiment 1, the discharge voltage characteristic is used as the battery characteristic. For example... Figure 3 As shown, the discharge voltage characteristics are calculated based on the voltage shift of the secondary battery 2 when it is discharged to the discharge target voltage VP. The discharge target voltage VP is not particularly limited and can be set to a voltage below the lower limit of the commonly used range Vn of the voltage value of the secondary battery 2.

[0075] The aforementioned voltage shift can be calculated based on at least one of, for example, the range capacity of the secondary battery 2 in a specified voltage range Vs, the ratio of the voltage change of the secondary battery 2 in the specified voltage range Vs to the capacity change of the secondary battery 2, and the ratio of the voltage change of the secondary battery 2 in the specified voltage range Vs to the elapsed time.

[0076] The specified voltage range Vs can be set as a voltage range that represents the relationship between the degradation degree of the secondary battery 2 and the progression of the battery state. Such a voltage range Vs can be set based on the type and structure of the secondary battery 2, or derived using machine learning of the secondary battery 2. For example, in this embodiment 1, as... Figure 3 As shown, the specified voltage range Vs is defined as the interval from voltage value V1 to V2. This voltage range Vs is the interval where the difference in discharge voltage characteristics becomes significant depending on the degree of degradation of the secondary battery 2.

[0077] Furthermore, in this embodiment 1, Figure 1 The capacity estimation unit 64 shown estimates the total capacity of the secondary battery 2 based on the battery characteristics acquired by the battery characteristic acquisition unit 63. The secondary battery 2 is determined by the applicability determination unit 62 to be suitable for degradation assessment. The total capacity estimation can utilize predictive models such as regression equations based on pre-acquired training data, for example, linear regression, LASSO regression, Ridge regression, decision trees, support vector regression, etc.

[0078] Figure 1 The degradation degree determination unit 65 shown determines the degradation degree of the secondary battery 2 based on battery characteristics or battery characteristic-related values. The battery characteristic-related values ​​are values ​​calculated based on battery characteristics; in this embodiment 1, the estimation result of the capacity estimation unit 64 is used as the battery characteristic-related value. Therefore, in this embodiment 1, the degradation degree determination unit 65 determines the degradation degree of the secondary battery 2 based on the estimation result of the capacity estimation unit 64. The determination method can be performed by comparing the estimation result of the capacity estimation unit 64 with the reference values ​​pre-stored in the reference value storage unit 52.

[0079] Figure 1 The update unit 8 shown is composed of a predetermined computing device and includes a reference value update unit 81. The reference value update unit 81 updates the approval / disapproval criteria and degradation degree criteria stored in the reference value storage unit 52. This update can be performed as follows: the charge / discharge control unit 71 charges and discharges a secondary battery that is determined by the approval / disapproval unit 62 to be unsuitable for degradation degree determination to obtain a measured value of the total capacity, and uses this measured value as additional training data to update the approval / disapproval criteria and degradation degree criteria stored in the reference value storage unit 52.

[0080] The following describes the method for determining the degree of degradation of the degradation degree determination device 1 based on Embodiment 1.

[0081] First of all, Figure 5 In step S1 shown, as a preparation process, from Figure 2(a) shows the used battery pack 20, from which secondary batteries 21 to 26 are removed in module form. Then, in step S2, the remaining capacity of each of the secondary batteries 21 to 26 is discharged by the charge / discharge control unit 71. Figure 3 As shown, the discharge continues until the open-circuit voltage reaches the preset discharge target voltage VP. In the case that the secondary batteries 21 to 26 are nickel-metal hydride batteries, there is a possibility that a memory effect may occur in the secondary batteries 21 to 26. However, the memory effect is also released simultaneously in the secondary batteries 21 to 26 as the discharge voltage reaches or approaches the discharge target voltage VP.

[0082] Then, as Figure 5 The discharge of the remaining capacity in step S2 shown is... Figure 5 In step S3 shown, the battery characteristics of each secondary battery 21 to 26 are acquired by the battery characteristic acquisition unit 63. In this embodiment 1, the above-mentioned discharge voltage characteristic is acquired as the battery characteristic. As described above, the discharge voltage characteristic is based on Figure 3 The voltage shifts within the specified voltage range Vs of each of the secondary batteries 21 to 26 shown.

[0083] In this embodiment 1, as Figure 3 As shown, the battery characteristic acquisition unit 63 acquires the voltage-time change of the first secondary battery 21 as a voltage shift. This voltage-time change represents the voltage change relative to the time from the start of discharge T0 to the end of discharge T0. P1 The relationship between the elapsed time and the given time. Then, calculate the differential value of the voltage VA within the specified voltage range Vs, i.e. Figure 3 The slope of the tangent line at voltage VA, indicated by symbol 21A in the voltage-time variation curve shown, is used as the differential value of the discharge voltage characteristic of the first secondary battery 21. Additionally, as... Figure 3 As shown, for the second secondary battery 22, the voltage-time change is also acquired as the voltage shift, and the differential value at voltage VA within the specified voltage range Vs (shown by symbol 22A) is calculated. This differential value is used as the discharge voltage characteristic of the second secondary battery 22. Similarly, for the third to sixth secondary batteries 23, the voltage-time change is also acquired as the voltage shift, and the differential value at voltage VA is calculated as their respective discharge voltage characteristics.

[0084] Furthermore, in this embodiment 1, the voltage-time change is obtained as a voltage shift, and the differential value at voltage VA within a predetermined voltage range Vs is used as the discharge voltage characteristic. However, it is also possible to instead calculate the ratio of the voltage change between two points in the voltage-time change derived as a voltage shift, that is, the slope of the straight line through those two points in the voltage-time change curve, and use this ratio as the discharge voltage characteristic. For example, as Figure 3 Two points in the voltage-time variation of the first and second batteries 21 shown can be represented by the start time T of the voltage interval Vs. A1 and end time T A2 These two points can also be applied to other secondary batteries 22-26.

[0085] Then, as Figure 5 As shown in step S4, the battery information acquisition unit 61 acquires the battery characteristics acquired by the battery characteristic acquisition unit 63 as battery information. Subsequently, in step S5, the feasibility determination unit 62 determines whether the degradation degree determination is valid. Specifically, the feasibility determination unit 62 determines whether the distance between the feasibility determination benchmark stored in the benchmark value storage unit 52 and the battery information related value calculated from the acquired battery information is within a specified range, that is, whether the battery information related value is within a specified range. Figure 4 The determination of whether or not the degradation degree can be determined based on the benchmark shown is valid.

[0086] If the acquired battery information is not within the acceptable / unacceptable criteria, the acceptable / unacceptable determination unit 62 determines that the degradation degree cannot be determined, and proceeds to... Figure 5 The step S5 shown is incorrect. Then, in step S6, for the secondary batteries 21 to 26 whose degree of degradation cannot be determined, the degree of degradation is not determined, and the process proceeds to step S9, which will be described later.

[0087] On the other hand, Figure 5 In step S5, if the acquired battery information falls within the acceptable / unacceptable criteria, the acceptable / unacceptable determination unit 62 determines that a degradation degree determination can be performed, and proceeds to step S5. Then, in step S7, the capacity estimation unit 64 estimates the full charge capacity or full discharge capacity of the secondary batteries 21 to 26 based on the battery characteristics acquired by the battery characteristic acquisition unit 63. In this embodiment 1, the capacity estimation unit 64 estimates the total capacity of the secondary batteries 21 to 26 based on the correspondence between the discharge voltage characteristics and the total capacity stored in the correspondence storage unit 51, which is based on the prediction model.

[0088] Then, in Figure 5In step S8, the degradation degree determination unit 65 determines the degradation degree of secondary batteries 21-26 based on the total capacity estimated by the capacity estimation unit 64. Then, the process proceeds to step S9, ending the degradation degree determination. Next, step A is entered, and in step S10, the update unit 8 determines whether there are any secondary batteries that were determined by the approval / disapproval unit 62 in step S5 to be unsuitable for degradation degree determination. If no secondary batteries are determined to be unsuitable for degradation degree determination, the process proceeds to step S10 (No), ending the control flow. Conversely, if a secondary battery is determined to be unsuitable for degradation degree determination in step S5, the process proceeds to step S10 (Yes).

[0089] Then, in Figure 5 In step S11, for secondary batteries whose degradation level is not determined, the charge / discharge control unit 71 performs charge / discharge and measures the total capacity. Then, in step S12, the reference value update unit 81 uses this measured value as additional training data to update the validity / disability determination reference and degradation level determination reference stored in the reference value storage unit 52. These two reference values ​​are used for the next degradation level determination.

[0090] Next, the method of manufacturing refurbished products by reassembling secondary batteries 2, which constitute modules taken from used battery packs 20, into battery packs 20 will be described below.

[0091] First of all, Figure 6 In step S13, multiple secondary batteries 2 are prepared to be removed from the battery pack 20. Then, in step S14, the battery characteristics of each secondary battery 2 are acquired. This acquisition of battery characteristics is the same as that in the degradation degree determination device 1 of this embodiment 1. Then, in step S15, the secondary batteries 2 are graded based on these battery characteristics or based on battery characteristic-related values ​​calculated from these battery characteristics. In this embodiment 1, the total capacity of the secondary batteries 2 is estimated based on these battery characteristic-related values, and the secondary batteries 2 are graded based on whether the absolute value of the degradation degree of the secondary batteries 2 calculated from the total capacity is within a specified range. Furthermore, in this embodiment 1, the absolute value of the degradation degree is divided into a specified range of five levels, sequentially designated as level A, level B, level C, level D, and level E, starting from the level with the smallest absolute value of degradation degree. In addition, the grading criteria can be appropriately set.

[0092] Next, in Figure 6In step S16, secondary batteries 21 to 26 are selected based on their grade. In this embodiment 1, they are differentiated according to each grade. As a result, the secondary batteries 2 included in the same grade have the same degree of deterioration. Then, in step S17, secondary batteries 2 of the same grade are combined to assemble a battery pack 20 to produce a refurbished product. As a result, the absolute value of the degree of deterioration of the secondary batteries 2 included in the refurbished product's battery pack 20 is the same, and the difference in degree of deterioration can be below a predetermined reference value. Furthermore, the reference value for the difference in degree of deterioration can be appropriately set according to the grading reference. In addition, although the battery pack 20 is made using secondary batteries 2 of the same grade in this embodiment 1, it is not limited to this. The battery pack 20 can also be made within a predetermined range of grades. For example, the battery pack 20 can also be made using secondary batteries 2 included in grades A and B. Furthermore, secondary batteries 2 of grade E, which are classified as the lowest grade, can also be considered unusable and discarded or disassembled for component recycling.

[0093] Subsequently, in this embodiment 1, in Figure 6 In step S18, as shown, the battery pack 20 is recharged. As a result, the secondary batteries 21-26 are ready to be used as battery pack 20.

[0094] Next, the effects of the degradation degree determination device 1 in this embodiment 1 will be described in detail.

[0095] In the degradation degree determination apparatus 1 of this embodiment 1, the degradation degree of the secondary battery is determined based on battery characteristics related to voltage shift within a predetermined voltage range obtained from the secondary battery 2, or based on battery characteristic correlation values. Therefore, degradation degree determination can be performed in a simple process. Moreover, by setting a voltage range in which the voltage shift of the secondary battery 2 shows a high correlation with degradation degree, the degradation degree of the secondary battery 2 can be determined with high accuracy, as the voltage range used to obtain the battery characteristics of the secondary battery 2. Then, before determining the degradation degree of the secondary battery 2, after determining whether degradation degree determination can be performed for each secondary battery 2, the degradation degree determination is performed for the secondary batteries 2 that are determined to be eligible for degradation degree determination. Therefore, by determining the degradation degree of secondary batteries 2 that can sufficiently ensure determination accuracy, the overall determination accuracy can be improved.

[0096] Furthermore, in this embodiment 1, the approval / disapproval determination unit 62 makes the approval / disapproval determination based on the comparison result between the battery information correlation value and the approval / disapproval determination criterion. The battery information correlation value is calculated from the battery information obtained by the battery information acquisition unit 61 using a pre-set relational formula related to multiple battery information values. Therefore, by appropriately adjusting the relational formula, the accuracy of the determination can be improved.

[0097] Furthermore, according to the degradation degree determination device 1 of this embodiment 1, a battery pack 20 can be provided that includes multiple secondary batteries 2 with a usage history, and the battery characteristics of the secondary batteries 2 related to the shift of battery state within a predetermined voltage range Vs, or the battery characteristic correlation value calculated based on the battery characteristics, are within a predetermined range. In such a refurbished battery pack, a battery pack 20 with small differences in battery characteristics can be provided. Moreover, by setting the voltage range Vs for obtaining the battery characteristics of the secondary batteries 2 to a voltage range where the voltage shift of the secondary batteries 2 shows a high correlation with the degradation degree, the difference in degradation degree of the secondary batteries 2 included in the battery pack 20 is reduced, thereby achieving a longer lifespan and improved quality of the battery pack 20.

[0098] Furthermore, although in this embodiment 1, the capacity estimation unit 64 estimates the total capacity of the secondary batteries 21-26 based on the battery characteristics acquired by the battery characteristic acquisition unit 63, and the degradation degree determination unit 65 determines the degradation degree of the secondary batteries 21-26 based on the estimation result, it is also possible that, instead of estimating the total capacity, the degradation degree determination unit 65 determines the degradation degree of the secondary batteries 21-26 based on the battery characteristics acquired by the battery characteristic acquisition unit 63. Alternatively, the battery characteristic acquisition unit 63 may acquire the absolute value of the acquired value as the battery characteristic, and the degradation degree determination unit 65 may determine the degradation degree based on this absolute value. Alternatively, the degradation degree determination unit 65 may determine the degradation degree of the secondary batteries 21-26 based on the difference in battery characteristics acquired by the battery characteristic acquisition unit 63.

[0099] Furthermore, although in this embodiment 1, the secondary batteries 21 to 26 are classified and assembled into battery pack 20 in such a way that the degree of degradation of the secondary batteries 21 to 26 is within a specified range, the secondary batteries 21 to 26 may also be classified and assembled into battery pack 20 in such a way that the degree of degradation of the secondary batteries 21 to 26 is within a specified range and the difference between the degree of degradation is within a specified range.

[0100] Furthermore, in this embodiment 1, the battery characteristics are set as discharge voltage characteristics based on the voltage shift within a predetermined voltage range Vs1 and Vs2 of the secondary batteries 21 to 26. When the secondary batteries 21 to 26 are nickel-metal hydride batteries, during the reuse of used secondary batteries 21 to 26, they are sometimes discharged for purposes such as eliminating the memory effect. However, by obtaining the aforementioned discharge voltage characteristics during this discharge, the work process for reusing the secondary batteries 21 to 26 can be simplified.

[0101] Furthermore, in this embodiment 1, the discharge voltage characteristics are calculated based on the voltage shift during the discharge of the secondary battery 2. However, alternatively, or in addition to this, the discharge voltage characteristics can be calculated based on the voltage shift during voltage relaxation when the battery returns to the open-circuit voltage after being discharged to the discharge target voltage VP and stopping the discharge. For example, as... Figure 7 As shown in variant 1, in the first secondary battery 21, the discharge time T can be stopped based on the discharge target voltage VP. P1 The differential value at the specified voltage VA (represented by symbol 21A) is calculated from the voltage shift within the specified voltage range Vs during subsequent voltage relaxation as the discharge voltage characteristic. Similarly, in the second secondary battery 22, the discharge voltage characteristic can be calculated based on the time T after the discharge has stopped. P2 The differential value at the specified voltage VA (represented by symbol 22A) is calculated from the voltage shift within the specified voltage range Vs during subsequent voltage relaxation as the discharge voltage characteristic. Similarly, for other secondary batteries 23-26 (not shown), the discharge voltage characteristics based on the voltage shift within the specified voltage range Vs during voltage relaxation can also be obtained. In this case, the same effect as in Embodiment 1 is achieved.

[0102] Furthermore, in this embodiment 1, a capacity estimation unit 64 is provided. This capacity estimation unit 64 uses the battery characteristics acquired by the battery characteristic acquisition unit 63 to estimate the total capacity of the secondary battery as a battery characteristic related value. The degradation degree determination unit 65 determines the degradation degree of the secondary batteries 21 to 26 based on the estimation result of the capacity estimation unit 64. As a result, the degradation degree of the secondary batteries 21 to 26 can be detected with high precision.

[0103] In this embodiment 1, as a voltage shift, the proportion of the voltage change of the secondary battery 2 within a specified voltage range Vs relative to the elapsed time, i.e., the differential value of the voltage-time change, is calculated, and this differential value is used as the discharge voltage characteristic. Therefore, the degree of degradation of the secondary battery 2 can be determined with high accuracy and ease.

[0104] Furthermore, the battery characteristic acquisition unit 63 can also calculate the voltage change of the secondary battery 2 relative to the elapsed time within a specified voltage range Vs as the voltage shift, or simultaneously, such as... Figure 8 As shown in Modification 2, the capacity change of each secondary battery 21-26 within the specified voltage range Vs is calculated as the range capacity Qp, and this range capacity Qp is used as the discharge voltage characteristic. The range capacity Qp can be calculated based on the current value flowing through the secondary batteries 21-26 within the voltage range Vs and the time the current flows, detected by the current value detection unit 32. In this case, the degree of degradation of the secondary battery 2 can also be determined with high accuracy and ease based on this discharge voltage characteristic.

[0105] Alternatively, the full range T0 to T1 during discharge of each of the secondary batteries 21 to 26 can also be calculated. P1 T0~T P2 capacity Figure 8 The total charge / discharge capacity Qt is shown, and the capacity ratio, which is the ratio of the interval capacity Qp to the total charge / discharge capacity Qt, is calculated and used as the discharge voltage characteristic. Alternatively, instead of the total charge / discharge capacity Qt, a specific interval capacity Qt', which includes the capacity of a specific voltage range used to calculate battery characteristics, can be calculated, and the capacity ratio, which is the ratio of the interval capacity Qp to the specific interval capacity Qt', can be calculated and used as the discharge voltage characteristic. In this case, the degree of degradation of the secondary battery 2 can be determined with high accuracy and ease based on this discharge voltage characteristic.

[0106] Furthermore, in this embodiment 1, the voltage-time change is obtained as the voltage shift as the discharge voltage characteristic, and the differential value at voltage VA within a predetermined voltage range Vs is used. However, it is also possible to use alternatives such as... Figure 9 As shown in variant 3, the voltage-capacity change is obtained as a voltage shift, which represents the voltage change relative to the capacity Q0 at the start of discharge and the capacity Q at the end of discharge. P1 The relationship between the capacity and the voltage can be determined. Furthermore, the differential value at voltage VA within the specified voltage range Vs, i.e., the slope of the tangent line at voltage VA in the voltage-capacity change curve, can be calculated, and this differential value can be used as the discharge voltage characteristic of the first secondary battery 21. In this case, it achieves the same effect as in Embodiment 1.

[0107] Furthermore, in this embodiment 1, the battery characteristics are calculated and obtained in the battery characteristic acquisition unit 63 provided in the degradation degree determination device 1. However, instead, the degradation degree determination device 1 may have an external input unit, and the battery characteristics may be calculated using an externally provided computing device, and then the battery characteristics may be input to the battery characteristic acquisition unit 63 via the external input unit, thereby obtaining the battery characteristics.

[0108] Furthermore, in Implementation 1, the discharge voltage characteristic was used as a battery characteristic, but in Figure 10 In the variation 4 shown, the battery characteristics may also include charging voltage characteristics based on the voltage shift when the secondary batteries 21-26 are charged to a predetermined charging target voltage VQ. The charging target voltage VQ is not particularly limited, but in this embodiment 1, it is set to a value larger than the lower limit of the normally used range Vn and smaller than the upper limit. Other structural elements are the same as in embodiment 1.

[0109] In this variation 4, the calculation of the voltage shift during charging can be performed in the same way as the calculation of the voltage shift in the discharge voltage characteristics in Embodiment 1 and each variation, and the calculated result is used as the charging voltage characteristic. That is, as... Figure 10 As shown, the voltage-time change is obtained as a voltage shift, which represents the voltage change relative to the point where the discharge ends (T). P1 T P2 From the start of charging to the end of charging (T) Q1 T Q2 The relationship between the elapsed time and the given time. Then, calculate the differential value of the voltage VB within the specified voltage range VsB, i.e. Figure 10 The slope of the tangent line at voltage VB, indicated by symbol 21B in the voltage-time variation curve, is used as the differential value of the charging voltage characteristic of the first secondary battery 21. Additionally, as shown... Figure 10 As shown, for the second secondary battery 22, the voltage-time change is also acquired as a voltage shift, and the differential value at voltage VB within the specified voltage range Vs (shown by symbol 22B) is calculated. This differential value is used as the discharge voltage characteristic of the second secondary battery 22. Similarly, for the third to sixth secondary batteries 23 to 26, the voltage-time change is also acquired as a voltage shift, and the differential value at voltage VB is calculated as their respective charging voltage characteristics. Furthermore, the specified voltage range VsB is set as the range from voltage value V3 to V4, which is the range where the difference in charging voltage characteristics becomes significant depending on the degree of degradation of the secondary battery 2.

[0110] Furthermore, the charging voltage characteristic can also be set as the ratio of the voltage change between the start times TB11 and TB21 and the end times TB12 and TB22 of the specified voltage range VsB, similar to the case of calculating the discharge voltage characteristic in Embodiment 1 above, or as the range capacity Qp in the voltage range VsB, or by calculating the entire range T during charging. P1 ~T Q1 T P2 ~T Q2 The capacity, i.e. the total charge-discharge capacity QT when charged to the target charging voltage VQ, is set as the ratio of the interval capacity Qp to the total charge-discharge capacity QT.

[0111] Furthermore, in this modified embodiment 4, the battery characteristic acquisition unit 63 acquires both the discharge voltage characteristic and the charging voltage characteristic, and the capacity estimation unit 64 estimates the total capacity of the secondary battery 2 based on these characteristics. Therefore, the degree of degradation of the secondary battery 2 can be determined with even higher accuracy.

[0112] Furthermore, when manufacturing a refurbished battery pack 20 using the degradation degree determination device 1 of this modified method 4, since each secondary battery 2 is charged before assembling the battery pack 20, it is not necessary to... Figure 6 The battery pack 20 is recharged in step S18.

[0113] In addition, in this modified embodiment 4, the battery characteristic acquisition unit 63 acquires the charging voltage characteristic after acquiring the discharge voltage characteristic by charging after discharging the secondary battery 2. However, it is not limited to this. It is also possible to acquire the discharge voltage characteristic after acquiring the charging voltage characteristic by discharging the secondary battery 2 after charging.

[0114] Furthermore, in this modified embodiment 4, the battery characteristic acquisition unit 63 acquires both the discharge voltage characteristic and the charging voltage characteristic, but it is also possible to acquire only the charging voltage characteristic instead. In this case, the judgment accuracy may deteriorate compared to acquiring both the discharge voltage characteristic and the charging voltage characteristic. On the other hand, when the secondary batteries 21 to 26 are nickel-metal hydride batteries, a memory effect may occur. When only the discharge voltage characteristic is acquired, the discharge voltage characteristic may deviate due to the voltage shift caused by the memory effect, thus inhibiting the improvement of judgment accuracy. However, when only the charging voltage characteristic acquired after the remaining capacity has been discharged is acquired, the charging voltage characteristic is the characteristic after the memory effect has been eliminated, so the influence of the memory effect is less, and therefore, an improvement in judgment accuracy can be expected.

[0115] Furthermore, the charging voltage characteristic in this variation 4 can also be calculated, similarly to the discharging voltage characteristic in embodiment 1, based on the voltage shift during voltage relaxation when charging returns to the open-circuit voltage after charging has stopped at a predetermined target charging voltage VQ. For example, it could also be as follows: Figure 11 As shown in variant 5, in the first and secondary batteries 21, based on the charging stop time T Q1 The voltage shift within the specified voltage range VsB during subsequent voltage relaxation is used to calculate the differential value at the specified voltage VB (shown by symbol 21B) as the charging voltage characteristic. Similarly, in the second secondary battery 22, the charging stop time T can also be used as the basis for the characteristic. Q2 The voltage shift within the specified voltage range VsB during subsequent voltage relaxation is used to calculate the differential value at the specified voltage VB (represented by symbol 22B) as the charging voltage characteristic. In this case, it also achieves the same effect as in Embodiment 1.

[0116] As described above, a secondary battery degradation determination device 1 can be provided that improves operability when determining the degradation degree of secondary batteries 21 to 26 constituting the battery pack 20.

[0117] Furthermore, in this modified embodiment 4, the degradation degree of the secondary battery 2 can be determined by the degradation degree determination unit 65 based on the battery characteristics acquired by the battery characteristic acquisition unit 63 without presuming the total capacity, similar to the modified embodiment 1. Alternatively, the battery characteristic acquisition unit 63 can acquire the absolute value of the acquired value as the battery characteristic, and the degradation degree determination unit 65 can determine the degradation degree based on this absolute value. Alternatively, the degradation degree determination unit 65 can also determine the degradation degree of the secondary battery 2 based on the difference between the battery characteristics acquired by the battery characteristic acquisition unit 63. Furthermore, the secondary batteries 2 can be classified and assembled into battery pack 20 in such a way that the degradation degree of the secondary battery 2 and the difference between the degradation degrees are within a predetermined range.

[0118] (Implementation Method 2)

[0119] In the degradation determination device 1 of Embodiment 1 described above, the battery information acquisition unit 61 acquires the battery characteristics of the secondary battery 2 acquired by the battery characteristic acquisition unit 63 as battery information. However, in Embodiment 2, the historical information of the secondary battery 2 is acquired as battery information. The historical information of the secondary batteries 21 to 26 can be set as the maximum, minimum, average, or cumulative value of the charging capacity, discharging capacity, battery temperature, state of charge (SOC), number of equalization cycles, outside air temperature, usage period of the device equipped with the secondary battery, temperature, etc., within a specified period. This specified period can be any period up to the present or the entire period up to the present. Other structures are the same as in Embodiment 1, and the same symbols as in Embodiment 1 are used, and their descriptions are omitted.

[0120] Furthermore, in the degradation determination process of this embodiment 2, such as Figure 12 As shown, firstly, step S1 is performed in the same manner as in Embodiment 1. Then, step S40 is entered, where the battery information acquisition unit 61 attempts to acquire battery information for the secondary batteries 21-26. In this Embodiment 2, the battery information acquisition unit 61 attempts, for example, to acquire historical charging information of each of the secondary batteries 21-26 as battery information A, and attempts to acquire historical temperature information of each of the secondary batteries 21-26 as battery information B. Furthermore, the types of historical information attempted to be acquired are not limited to these.

[0121] Next, in Figure 12 In step S41, it is determined whether battery information A and B can be acquired by the battery information acquisition unit 61. If battery information A and B cannot be acquired in step S41, the process proceeds to step S41 (no), and in step S42, the process ends without determining the degree of degradation of the secondary battery as a measurement failure.

[0122] On the other hand, Figure 12If battery information is obtained in step S41, the process proceeds to step S41. Furthermore, in step S5, the feasibility of the degradation determination is determined by the feasibility determination unit 62, similar to the case in Embodiment 1. For secondary batteries 21-26 whose obtained battery information is not within the feasibility determination criteria, it is determined that degradation determination cannot be performed, and steps S6 and S9 are performed similarly to the case in Embodiment 1, proceeding to... Figure 5 Mark A, proceed to steps S10 to S12 and end the process.

[0123] On the other hand, Figure 12 In step S5, for secondary batteries 21-26 whose acquired battery information falls within the acceptable determination criteria, the acceptable determination unit 62 determines that a degradation degree determination can be performed, and proceeds to step S5. Then, in step S20, for the secondary batteries 21-26 that are determined to be eligible for degradation degree determination, and... Figure 5 In the same manner, step S5 of Embodiment 1 is performed to discharge the remaining capacity. Furthermore, in the case that the secondary batteries 21-26 are nickel-metal hydride batteries, the memory effect is also simultaneously eliminated.

[0124] Subsequently, in step S21, for the secondary battery that is determined to be capable of undergoing a degradation assessment, and... Figure 5 In step S3 of Embodiment 1, the discharge voltage characteristic is obtained as a battery characteristic. Then, steps S7 to S12 are performed in the same manner as in Embodiment 1, and the process ends.

[0125] In this embodiment 2, the battery information acquisition unit 61 acquires historical information of the secondary batteries 21-26 as battery information. Therefore, since the determination of the degree of degradation is based on the historical information of the secondary batteries 21-26, the accuracy of the determination can be improved.

[0126] In the degradation degree determination device 1 of Embodiment 1 described above, the battery information acquisition unit 61 acquires the battery characteristics of the secondary battery 2 acquired by the battery characteristic acquisition unit 63 as battery information. In the degradation degree determination device 1 of Embodiment 2, the battery information acquisition unit 61 acquires the historical information of the secondary battery 2 as battery information. Instead, in the degradation degree determination device 1 of Modification 6, the configuration is to acquire both the battery characteristics acquired by the battery characteristic acquisition unit 63 and the historical information of the secondary battery 2 as battery information. Other structures are the same as in Embodiments 1 and 2, and the same symbols are used as in Embodiments 1 and 2, and their descriptions are omitted.

[0127] Then, in the process of determining the degree of degradation in deformation mode 6, such as Figure 13As shown, firstly, steps S1, S40, and S41 are performed in the same manner as in Embodiment 2. If battery information cannot be obtained in step S41, the process proceeds to step S41 (No) in the same manner as in Embodiment 2, and in step S42, the process ends without determining the degree of degradation of the secondary battery 2 as a measurement failure.

[0128] On the other hand, Figure 13 In step S41, if battery information is obtained, similarly to the case in Embodiment 2, in step S20, the remaining capacity of the secondary battery for which battery information has been obtained is discharged, and if the secondary battery is a nickel-metal hydride battery, the memory effect is also released simultaneously. Then, in step S21, battery characteristics are obtained similarly to the case in Embodiment 2, and the process proceeds to step S50.

[0129] exist Figure 13 In step S50, the approval / disapproval determination unit 62 determines whether the degree of degradation can be determined based on the battery characteristics and historical information of the secondary batteries 21-26 (which serve as battery information) and the approval / disapproval criteria. For secondary batteries 21-26 whose acquired battery information does not fall within the approval / disapproval criteria, it is determined that the degree of degradation cannot be determined, and steps S6 and S9 are performed in the same manner as in Embodiment 1, proceeding to the next step. Figure 5 If the symbol A is found, proceed to steps S10 to S12 and end the process. On the other hand, for secondary batteries 21 to 26 that are determined to be capable of degradation assessment, proceed to steps S7 to S9 in the same manner as in Embodiment 1 and proceed to... Figure 5 Mark A, proceed to steps S10 to S12 and end the process.

[0130] According to this variation 6, as described above, since the battery information used for determining the feasibility of degradation includes both the battery characteristics and historical information of the secondary batteries 21-26, it is possible to further determine the feasibility of degradation with higher accuracy. Furthermore, this variation 6 also achieves the same effect as in embodiments 1 and 2.

[0131] (Implementation Method 3)

[0132] The degradation degree determination device 1 of this embodiment 3 has a similar function to... Figure 12 The structure is the same as in Embodiment 2. Furthermore, in this Embodiment 3, the reference value storage unit 52 stores a first disapproval reference D1 and a second disapproval reference D2. In this Embodiment 3, the first disapproval reference D1 stores a Mahalanobis distance D1 as the data distance D1, and the second disapproval reference D2 stores a Mahalanobis distance as the data distance; the relationship between the two is D1 < D2.

[0133] Furthermore, in this embodiment 3, a first correspondence and a second correspondence are stored in the correspondence storage unit 51. The first correspondence is applicable to determining the degree of degradation of a secondary battery that is determined by the first affirmative / negative determination criterion D1 to be capable of undergoing a degree of degradation determination. The second correspondence is applicable to determining the degree of degradation of a secondary battery that is determined by the second affirmative / negative determination criterion D2 to be capable of undergoing a degree of degradation determination. This correspondence can be created in the same manner as in embodiment 2.

[0134] Next, the following uses Figure 14 The flowchart of the degradation degree determination method of the degradation degree determination device 1 in this embodiment 3 will be described. Furthermore, in this embodiment 3, for... Figure 12 The same symbols are used for the structures in the illustrated embodiment 2, and their descriptions are omitted.

[0135] In the process of this embodiment 3, instead of Figure 12 The case of Implementation Method 2 shown is as follows: Figure 14 As shown, for the secondary batteries 21-26 that have obtained battery information in step S41, step S41 is entered, and in step S51, the possibility determination unit 62 determines whether the degradation degree of the secondary battery that has obtained battery information is possible based on the first possibility determination criterion D1. Then, in step S51, for the secondary batteries that are determined to be capable of degradation degree determination, step S51 is entered, and steps S22 and S23 are the same as steps S20 and S21 in the case of embodiment 2.

[0136] Subsequently, Figure 14 In step S71, the capacity estimation unit 64 estimates the total capacity of the secondary batteries 21-26 that were determined to be capable of degradation in step S51, based on the first correspondence between battery characteristics and total capacity stored in the prediction model in the correspondence storage unit 51, from the battery characteristic acquisition unit 63. This capacity is either the full charge capacity or the full discharge capacity. Then, similarly to the case in Embodiment 2, the degradation degree is determined in step S8, and step S9 is performed to proceed to the next step. Figure 5 Mark A, proceed to steps S10 to S12 and end the process.

[0137] On the other hand, Figure 14In step S51, for the secondary batteries 21-26 that cannot be determined for degree of degradation based on the first affirmative / negative determination criterion D1, the process proceeds to step S51 (NO). Then, in step S52, for the secondary batteries 21-26 that were determined in step S51 to be unable to be determined for degree of degradation, the affirmative / negative determination unit 62 determines whether a degree of degradation determination can be performed based on the second affirmative / negative determination criterion D2. Then, in step S52, if it is determined that a degree of degradation determination can be performed, the process proceeds to step S52, performing the same steps S24 and S25 as in steps S20 and S21 of Embodiment 2.

[0138] Subsequently, Figure 14 In step S72, the capacity estimation unit 64 estimates the total capacity of the secondary batteries 21-26 that were determined to be capable of degradation determination in step S52, based on the second correspondence between battery characteristics and total capacity stored in the prediction model in the correspondence storage unit 51, from the battery characteristic acquisition unit 63. This capacity is either the full charge capacity or the full discharge capacity. Then, similarly to Embodiment 2, the degradation degree is determined in step S8, and the process proceeds to step S9 to end the degradation degree determination. On the other hand, for secondary batteries 21-26 that were determined not to be capable of degradation determination in step S52, the process proceeds to step S52 (no), and similarly to Embodiment 1, proceeds to steps S6 and S9 to end the degradation degree determination. After step S9, the process proceeds to... Figure 5 Mark A, proceed to steps S10 to S12 and end the process.

[0139] In the degradation degree determination device 1 of this embodiment 3, as multiple affirmative / negative determination criteria, there are a first affirmative / negative determination criterion D1 and a second affirmative / negative determination criterion. As multiple correspondences, there are a first correspondence and a second correspondence applicable to secondary batteries that are determined to be capable of degradation degree determination based on their respective affirmative / negative determination criteria. Therefore, the consistency between the criteria for determining the affirmative / negative degree of degradation and the criteria for determining the degree of degradation is improved, enabling further high-precision determination of the degree of degradation. Furthermore, in this embodiment, the same effect as in the case of embodiment 1 is achieved.

[0140] (Implementation Method 4)

[0141] In the degradation degree determination device of embodiment 4, such as Figure 15As shown, the arithmetic unit 6 also includes a vehicle information acquisition unit 66. Vehicle information can include, for example, the vehicle model of the vehicle 100, the model of the battery pack, the secondary battery module, the position of the module in the battery pack, the manufacturing year of the vehicle 100, the usage period, the mileage, and the sales location of the vehicle 100. Furthermore, the reference value storage unit 52 stores vehicle information references as criteria for determining the feasibility of vehicle information used to determine the degree of degradation. In this embodiment 4, multiple specific vehicle models are stored as vehicle information. Additionally, the correspondence storage unit 51 stores correspondence relationships corresponding to each specific vehicle model. Other structures are similar to... Figure 1 The same symbols are used for Embodiment 1 shown and Embodiment 2 (not shown), and their descriptions are omitted.

[0142] Next, the flow of the degradation degree determination method of the degradation degree determination device 1 in Embodiment 4 will be described below. In Embodiment 4, the degradation degree determination method of the device 1 in Embodiment 4 is described below. Figure 12 The same symbols are used for the equivalent structures shown in Embodiment 2, and their descriptions are omitted. In the flow of this Embodiment 4, instead of... Figure 12 Step S40 of Embodiment 2 shown is as follows: Figure 16 As shown, after step S1, step S43 is performed, where the vehicle information acquisition unit 66 acquires vehicle information of the vehicle 100 equipped with the battery pack 20. Although the vehicle information is not limited to this, in this embodiment 4, the vehicle model of the vehicle 100 is acquired.

[0143] Subsequently, Figure 16 In step S44, the yes / no determination unit 62 determines whether the vehicle information acquired by the vehicle information acquisition unit 66 meets the vehicle information benchmark. In this embodiment 4, it is determined whether the vehicle model acquired by the vehicle information acquisition unit 66 meets the specific vehicle model stored in the benchmark value storage unit 52. In step S44, if it is determined that the vehicle model does not meet the specific vehicle model, the process proceeds to step S44 (no), and similarly to the case in embodiment 2, the process ends without determining the degree of degradation in step S42.

[0144] On the other hand, Figure 16In step S44, if it is determined that the acquired vehicle information meets the vehicle information benchmark, step S44 is entered. Then, steps S40-S42, S5-S6, and S20-S21 are performed in the same manner as in Embodiment 2. After step S21, for the secondary battery that is determined to be capable of degradation degree determination, in step S73, the capacity estimation unit 64 estimates the total capacity based on the vehicle information. That is, in the capacity estimation unit 64, the estimation formula used for estimating the total capacity is changed according to the vehicle information. Then, in step S8, the degradation degree determination unit 65 determines the degradation degree of secondary batteries 21-26 based on the estimated total capacity result. After step S8 and after step S6, step S9 is entered in the same manner as in Embodiment 2, and the degradation degree determination ends. Then, proceed to Figure 5 Mark A, proceed to steps S10 to S12 and end the process.

[0145] According to the degradation degree determination device 1 of this embodiment 4, the capacity estimation unit 64 can further improve the estimation accuracy by using an estimation formula that estimates the total capacity corresponding to the vehicle model as vehicle information to determine the degradation degree based on the vehicle model. In addition, the degradation degree determination device 1 of this embodiment 4 can also achieve the same effect as that of this embodiment 1.

[0146] (Implementation Method 5)

[0147] In the degradation degree determination device 1 of this embodiment 5, except for Figure 1 In addition to the structure of Embodiment 1 shown, such as Figure 17 As shown, the arithmetic unit 6 includes an impedance characteristic acquisition unit 67. The impedance characteristic acquisition unit 67 has a structure for performing complex impedance measurement, configured to measure the impedance of secondary batteries 21-26. Other structures are the same as in Embodiment 1; structures identical to those in Embodiment 1 are labeled with the same symbols and their descriptions are omitted.

[0148] In this fifth embodiment, the battery characteristic acquisition unit 63 acquires characteristics in the same manner as in the first embodiment. Figure 3 The discharge voltage characteristics within the specified voltage range Vs are shown. Furthermore, the impedance characteristic acquisition unit 67... Figure 3 The discharge ends at T P1 T P2 Perform complex impedance measurement to obtain the impedance at a specified frequency, and calculate the values ​​of the real axis and the imaginary axis on the complex plane.

[0149] Here, the impedance characteristic can be expressed using the real and imaginary axis values ​​of the impedance at a specified frequency f1, and the absolute value calculated from the real and imaginary axis values. Additionally, the deflection angle can be calculated using the real and imaginary axis values ​​at the specified frequency f1. Furthermore, the difference between the real axis values ​​and the imaginary axis values ​​at specified frequencies f1 and f2, the difference between the absolute values ​​calculated from the difference between the real and imaginary axis values, and the deflection angle can also be expressed.

[0150] Furthermore, the correspondence between impedance characteristics and total capacity is pre-stored in the correspondence storage unit 51. This correspondence can be generated by using machine learning of the secondary battery 2 for testing, or based on measured values ​​obtained from accelerated degradation tests using the secondary battery for testing, or by logically deriving a calculation formula for the correspondence between impedance characteristics and total capacity at a specified voltage using a model of the secondary battery.

[0151] In this fifth embodiment, similar to the first embodiment, after the approval / disapproval determination unit 62 determines whether the degradation degree determination is acceptable, Figure 17 The capacity estimation unit 64 shown estimates the total capacity of the secondary battery 2 based on the discharge voltage characteristics obtained by the battery characteristic acquisition unit 63 and the impedance characteristics obtained by the impedance characteristic acquisition unit 67. The degradation degree determination unit 65, similar to that in Embodiment 1, determines the degradation degree of the secondary battery 2 based on the estimation result of the capacity estimation unit 64. According to this Embodiment 5, since the total capacity is estimated based on the discharge voltage characteristics and impedance characteristics, the determination accuracy can be further improved.

[0152] Furthermore, in this embodiment 5, the time when the impedance characteristic acquisition unit 67 performs complex impedance measurement is set to the end of discharge T. P1 T P2 However, it is not limited to this and can be performed at other times. For example, if the battery characteristic acquisition unit 63 acquires the charging voltage characteristics as in Embodiment 3, it can also be performed at... Figure 12 The charging end T shown Q1 T Q2 Complex impedance is measured by the impedance characteristic acquisition unit 67. Alternatively, the capacitance estimation unit 64 can use a correlation value calculated based on the impedance characteristic instead of the impedance characteristic itself. For example, the difference in impedance characteristics acquired by the impedance characteristic acquisition unit 67 can be used as the correlation value.

[0153] Furthermore, according to the degradation degree determination device 1 of this embodiment 5, a battery pack 20 can be provided that includes multiple secondary batteries with a usage history, wherein the difference in degradation degree of each of the multiple secondary batteries, determined based on their total capacity, is within a specified range, and the total capacity is estimated using battery characteristics and impedance characteristics related to the impedance of the secondary batteries during discharge or charging. In this battery pack, since the difference in degradation degree of the secondary batteries included in the battery pack becomes smaller, it is possible to achieve a longer lifespan and improved quality for the refurbished battery pack.

[0154] Furthermore, in this embodiment 5, the degradation degree of secondary batteries 21-26 can be determined by the degradation degree determination unit 65 based on the battery characteristics and impedance characteristics acquired by the battery characteristic acquisition unit 63 without presuming the total capacity. Alternatively, the battery characteristic acquisition unit 63 can acquire the absolute value of the acquired values ​​as the battery characteristic, and the degradation degree determination unit 65 can determine the degradation degree based on this absolute value. Alternatively, the degradation degree determination unit 65 can determine the degradation degree of secondary batteries 21-26 based on the difference between the battery characteristics acquired by the battery characteristic acquisition unit 63. Alternatively, the secondary batteries 21-26 can be classified and assembled into battery pack 20 in such a way that the degradation degree of secondary batteries 21-26 and the difference between their degradation degrees are within a predetermined range.

[0155] (Implementation Method 6)

[0156] In this embodiment 6, except Figure 1 In addition to the structure of Embodiment 1 shown, such as Figure 18 As shown, it also includes an initial voltage acquisition unit 68. (As shown...) Figure 19 As shown, the initial voltage acquisition unit 68 acquires the initial voltages VI1 and VI2, which are the open-circuit voltages of the secondary battery 2 at the start of discharge T0. Furthermore, the correspondence between the initial voltage values, battery characteristics, and total capacity is pre-stored in the correspondence storage unit 51. This correspondence can be created in the same way as in Embodiment 1. Other structures are the same as in Embodiment 1; structures identical to those in Embodiment 1 are labeled with the same symbols, and their descriptions are omitted.

[0157] According to the degradation degree determination device 1 of this embodiment 6, since the degradation degree of the secondary battery 2 is determined by considering the initial voltage in addition to battery characteristics, the determination accuracy can be further improved with a simple structure. Furthermore, an initial voltage correlation value calculated based on the initial voltage can be used instead of the initial voltage. For example, the initial voltage correlation value can be set as the absolute value of the initial voltage, or as the difference between the initial voltages acquired by the initial voltage acquisition unit 68.

[0158] Furthermore, according to the degradation degree determination device 1 of this embodiment 6, a battery pack 20 can be provided that includes a plurality of secondary batteries 21 to 26, of which there are reusable components. The difference in degradation degree between the plurality of secondary batteries 21 to 26, determined based on their total capacity, is within a specified range. This total capacity is estimated using an initial voltage and battery characteristics, where the initial voltage is the open-circuit voltage of the secondary batteries 21 to 26 at the time the battery characteristics are first acquired. In this battery pack 20, since the difference in degradation degree between the secondary batteries 21 to 26 included in the battery pack 20 becomes smaller, it is possible to achieve a longer lifespan and improved quality for the refurbished battery pack 20.

[0159] Furthermore, in this embodiment 6, the degradation degree of the secondary batteries 21-26 can be determined by the degradation degree determination unit 65 based on the battery characteristics and initial voltage acquired by the battery characteristic acquisition unit 63, similar to a variation of embodiment 1. Alternatively, the battery characteristic acquisition unit 63 can acquire the absolute value of the acquired value as the battery characteristic, and the degradation degree determination unit 65 can determine the degradation degree based on this absolute value. Alternatively, the degradation degree determination unit 65 can determine the degradation degree of the secondary batteries 21-26 based on the difference between the battery characteristics acquired by the battery characteristic acquisition unit 63. Furthermore, the secondary batteries 21-26 can be classified and assembled into battery pack 20 in such a way that the degradation degree of the secondary batteries 21-26 and the difference between their degradation degrees are within a predetermined range.

[0160] Alternatively, as another variation 7, it could also be, for example... Figure 20 As shown, the arithmetic unit 6 includes an internal resistance acquisition unit 69 for acquiring the internal resistance of secondary batteries 21-26, and a correspondence between internal resistance, battery characteristics, and total capacity is pre-stored in the correspondence storage unit 51. In the internal resistance acquisition unit 69, the internal resistance can be acquired by calculating based on the measured voltage (which is the voltage value detected by the voltage value detection unit 31), the open-circuit voltage of secondary batteries 21-26, and the current flowing through secondary batteries 21-26. Furthermore, the open-circuit voltage of secondary battery 2 can be estimated at each time interval using a mapping representing the correspondence between the remaining discharge capacity and the initial voltage of secondary batteries 21-26. According to the degradation degree determination device 1 of this modified embodiment 7, the degradation degree of secondary batteries 21-26 is determined by considering internal resistance in addition to battery characteristics, thus further improving the determination accuracy with a simplified structure.

[0161] (Implementation Method 7)

[0162] like Figure 21 As shown, the degradation degree determination device 1 of this embodiment 7, in addition to Figure 1In addition to the structure shown in Embodiment 1, a temperature detection unit 33 is also included. Furthermore, in Embodiment 1, the battery characteristic acquisition unit 63 is configured to acquire the discharge voltage characteristic of the secondary battery 2 based on the voltage shift within a predetermined voltage range Vs as the battery characteristic. However, in this Embodiment 7, instead, the battery characteristic acquisition unit 63 acquires the temperature characteristic of the secondary battery 2 based on the temperature shift within predetermined voltage ranges VsA and VsB as the battery characteristic. Other structures are the same as in Embodiment 1; the same reference numerals are used for structures identical to those in Embodiment 1, and their descriptions are omitted. Furthermore, voltage range VsA is the range where the difference in discharge voltage characteristics becomes significant depending on the degree of degradation of the secondary battery 2, and voltage range VsB is the range where the difference in charging voltage characteristics becomes significant depending on the degree of degradation of the secondary battery 2.

[0163] In this embodiment 7, as Figure 22 of (a), Figure 22 As shown in (b), the temperature of the secondary battery 2 during charging and discharging is obtained by the temperature detection unit 33. In this embodiment 7, the secondary battery 2 that is the object of the degradation determination is a first secondary battery 21 taken from the battery pack 20 and a seventh secondary battery 27 taken from another battery pack.

[0164] Depending on the assembled battery pack, the temperature shift of the secondary battery 2 during charging and discharging can exhibit different behaviors due to the measurement environment and insulation conditions of the secondary battery 2. In this embodiment 7, as... Figure 22 As shown in (b), the temperature shifts in the first secondary battery 21 and the seventh secondary battery 27 converge within the measured room temperature set range Tn, but exhibit slightly different behaviors. Furthermore, in this embodiment 7, the battery characteristic acquisition unit 63 acquires the temperature characteristics during discharge and charging based on the battery temperatures detected by the temperature detection unit 33 within both a predetermined voltage range sA during discharge and a predetermined voltage range VsB during charging after discharge. Then, the capacity estimation unit 64 estimates the total capacity of each secondary battery 21, 27 based on the two temperature characteristics, and the degradation determination unit 65 determines the degree of degradation.

[0165] The temperature characteristics acquired by the battery characteristic acquisition unit 63 can be set to the differential value of the temperature change at specified voltages VA and VB in the specified voltage ranges VsA and VsB, or to the ratio of the temperature change between two points in the specified voltage ranges VsA and VsB, or to the ratio of the temperature change of the secondary battery 2 to the capacity change of the secondary battery 2 in the voltage ranges VsA and VsB.

[0166] In this embodiment 7, the same effect as in embodiment 1 can be achieved. Furthermore, in this embodiment 7, the temperature characteristic is obtained from both discharging and charging, but it is not limited to this; it may be set to only one of discharging and charging.

[0167] Furthermore, according to the degradation degree determination device 1 of this embodiment 7, a battery pack can be provided that includes secondary batteries with a usage history, wherein the difference in degradation degree of each of the multiple secondary batteries, determined based on the total capacity estimated from the battery usage characteristics, is within a specified range, and the battery characteristics include temperature characteristics based on the temperature shift of the secondary batteries within a specified voltage range VsA, VsB. In this battery pack, since the difference in degradation degree of the secondary batteries included in the battery pack becomes smaller, the quality of the battery pack as a refurbished product can be improved.

[0168] Furthermore, in this embodiment 7, the degradation degree of secondary batteries 21-26 can be determined by the degradation degree determination unit 65 based on the temperature characteristics acquired by the battery characteristic acquisition unit 63 without presuming the total capacity. Alternatively, the absolute value of the acquired value can be used as the temperature characteristic, and the degradation degree determination unit 65 can determine the degradation degree based on this absolute value. Alternatively, the degradation degree determination unit 65 can determine the degradation degree of secondary batteries 21-26 based on the difference between the temperature characteristics acquired by the battery characteristic acquisition unit 63. Alternatively, the secondary batteries 21-26 can be classified and assembled into battery pack 20 in such a way that the degradation degree of secondary batteries 21-26 and the difference between their degradation degrees are within a specified range.

[0169] In this embodiment 7, as Figure 22 As shown in (a), the temperature characteristics during charging are obtained when the target charging voltage VQ is within the normal operating range Vn and has a specified voltage range VsA within the normal operating range Vn. However, this can be replaced by, as shown in... Figure 23 As shown in variation 8 of (a), the temperature characteristics during charging are obtained when the target charging voltage VQ exceeds the normal operating range Vn and a specified voltage range VsB exists in the region exceeding the normal operating range Vn. In this case, as... Figure 23 As shown in (b), the temperature of secondary batteries 21 and 27 tends to rise, and therefore the degree of degradation is easily reflected in the temperature change. As a result, the accuracy of the determination can be improved. Furthermore, in this modified embodiment 8, the voltages of secondary batteries 21 and 27 are returned to the normal operating range Vn after being charged to the target charging voltage VQ.

[0170] In addition, in variant 8, after the secondary battery 2 is discharged, it is charged and then discharged again. However, this can be replaced by other methods, such as... Figure 24 of (a), Figure 24 As shown in variation 9 (b), charging is performed before discharging, without first discharging. In this case, the battery characteristic acquisition unit 63 can acquire the temperature characteristics during charging and then acquire the temperature characteristics during discharging. In this case, it also achieves the same effect as in embodiment 1.

[0171] (Implementation Method 8)

[0172] In Embodiment 1 described above, the capacity estimation unit 64, acting as the estimation unit, estimates the total capacity of the secondary battery 2 based on the battery characteristics acquired by the battery characteristic acquisition unit 63. However, it is not limited to this; the capacity estimation unit 64 can also estimate the positive electrode capacity, negative electrode capacity, the offset of the relative relationship between the negative electrode SOC and the positive electrode SOC, the total capacity difference among the multiple cells constituting the secondary batteries 21 to 26, and at least one of the battery resistance, positive electrode resistance, and negative electrode resistance of the secondary batteries 21 to 26. Furthermore, in Embodiment 8, the capacity estimation unit 64 estimates the positive electrode capacity Qc of each of the secondary batteries 21 to 26. Moreover, the correspondence between battery characteristics and positive electrode capacity Qc is stored in the correspondence storage unit 51. The form and method of creating this correspondence are not particularly limited, and can be in the same form as in Embodiment 1, such as a calculation formula, mapping, chart, table, etc. This correspondence can be created by using machine learning with the secondary battery 2 for measurement, or by using measured values ​​obtained from accelerated degradation tests with the secondary battery 2 for measurement, or by logically deriving a calculation formula for the correspondence between battery characteristics and total capacity within a specified voltage range using a model of the secondary battery 2. In this embodiment, the correspondence storage unit 51, for example, is based on... Figure 25 The prediction models shown in (a) to (c) store the correspondence between battery characteristics and positive electrode capacity Qc. Other structures are the same as in Embodiment 1, and the same symbols are used as in Embodiment 1, with their descriptions omitted.

[0173] Next, the method for determining the degree of degradation of the degradation degree determination device 1 in Embodiment 8 will be described below. Furthermore, regarding... Figure 5 The steps in the illustrated embodiment 1 are the same, with the same symbols used and their descriptions omitted.

[0174] First, in this embodiment 8, with Figure 5 Similarly, in the case of Implementation Method 1 shown, the following is performed: Figure 26 Steps S1 to S5 are shown. Therefore, as... Figure 27As shown in (a), the battery characteristic acquisition unit 63 acquires discharge curves within a predetermined voltage range Vs as the battery characteristics of each secondary battery 21 to 26. Furthermore, the predetermined voltage range can be set to a range corresponding to a specific SOC range.

[0175] Next, in Figure 26 In step S74 shown, the capacity estimation unit 64 estimates the positive electrode capacity Qc of the secondary batteries 21-26 based on the prediction model stored in the correspondence storage unit 51 and the correspondence between battery characteristics and positive electrode capacity Qc, according to the discharge curves acquired by the battery characteristic acquisition unit 63. Subsequently, Figure 26 In step S8 shown, the degradation degree determination unit 65 determines the degradation degree of secondary batteries 21-26 based on the positive electrode capacity Qc estimated by the capacity estimation unit 64. Additionally, with... Figure 5 The situation is similar in Implementation Method 1 shown, after... Figure 26 After steps S9 and S10, in step S110, the charge / discharge control unit 71 charges and discharges the secondary battery (without determining its degradation level) to measure the actual value of the positive electrode capacity. Then, similarly to the case of Embodiment 1, in step S12, the acquisition criteria and degradation level determination criteria are updated.

[0176] In this embodiment 8, it also achieves the same effect as in embodiment 1. Furthermore, in this embodiment 8, the battery characteristic acquisition unit 63 acquires... Figure 27 The discharge curve shown in (a) can be obtained by alternative methods. Figure 27 The charging curve shown in (b) is as follows. In this case, it also has the same effect as in embodiment 1.

[0177] (Implementation Method 9)

[0178] In Embodiment 8 described above, the capacity estimation unit 64 estimates the positive electrode capacity Qc. However, in Embodiment 9, the capacity estimation unit 64 estimates the negative electrode capacity QA. That is, in Embodiment 9, as... Figure 28 As shown, in steps S75 and S111, based on Figure 25 The prediction models shown in (a) to (c) estimate the negative electrode capacity QA of secondary batteries 21 to 26 based on the correspondence between battery characteristics and negative electrode capacity QA. In this embodiment 9, it achieves the same effect as in embodiment 1.

[0179] (Implementation Method 10)

[0180] In this embodiment 10, the capacity estimation unit 64 estimates the offset of the relative relationship between the negative electrode SOC and the positive electrode SOC of each of the secondary batteries 21 to 26. Furthermore, the correspondence storage unit 51 stores the correspondence between battery characteristics and the offset of the relative relationship between the negative electrode SOC and the positive electrode SOC. The form and method of creating this correspondence are not particularly limited and can be set to be the same as in embodiment 1.

[0181] For example, in the case where secondary batteries 21-26 are composed of nickel-metal hydride batteries, such as Figure 29 As shown, when hydrogen is removed from the battery cell container from the reaction system, the relative relationship between the negative electrode SOC and the positive electrode SOC shifts, thus the OCV curve of the negative electrode shifts to the right of the graph. For example, in the case where secondary batteries 21-26 are composed of lithium-ion batteries, such as Figure 29 As shown, lithium in the electrolyte is consumed during the formation of the SEI (Solid Electrolyte Interface) coating, which shifts the relative relationship between the negative electrode SOC and the positive electrode SOC. Therefore, the OCV curve of the negative electrode shifts to the right side of the graph.

[0182] In this embodiment 10, based on Figure 29 The prediction model shown stores the offset Qx of the relative relationship between the negative electrode SOC and the positive electrode SOC and the correspondence between the battery characteristics in the correspondence storage unit 51. Other structures are the same as in Embodiment 1, and the same symbols are used as in Embodiment 1, and their descriptions are omitted.

[0183] The degradation degree determination method of the degradation degree determination device 1 in this embodiment 10 is performed in the same way as in the case of embodiment 8 described above, however, as Figure 30 As shown, in step S3, the battery characteristic acquisition unit 63 acquires the discharge curve of a predetermined voltage range Vs corresponding to the low SOC range of the battery as the battery characteristic. Subsequently, with... Figure 5 The same applies to the case of Embodiment 1 shown. Figure 30 Steps S4 to S5 are shown. Then, proceed to step S76, where the offset Qx of secondary batteries 21 to 26 is estimated based on the battery characteristics calculated from the discharge curve and the correspondence between the offset Qx of the relative relationship between the negative electrode SOC and the positive electrode SOC stored in the correspondence storage unit 51 and the battery characteristics. Subsequently, Figure 30In step S5 shown, the degradation degree of secondary batteries 21 to 26 is determined by the degradation degree determination unit 65 based on the offset Qx estimated by the capacity estimation unit 64. In this embodiment 10, it achieves the same effect as in embodiment 1. Furthermore, in this embodiment 10, battery characteristics are obtained from the low SOC range, but battery characteristics could also be obtained from the high SOC range instead. Additionally, in this embodiment 10, the discharge curve is obtained as the battery characteristic, but the charging curve could also be obtained as the battery characteristic.

[0184] (Implementation Method 11)

[0185] In this embodiment 11, the correspondence storage unit 51 stores the correspondence between battery characteristics and the change in discharge capacity in the charge-discharge curve for each secondary battery 21 to 26. The capacity estimation unit 64 estimates the change in discharge capacity in the charge-discharge curve within a specified voltage range Vs. The degradation degree determination unit 65 detects whether the self-discharge amount of a single cell has increased based on the estimation result as the degree of degradation. In this embodiment 11, other structures are the same as in embodiment 1, and the same symbols are used as in embodiment 1, and their descriptions are omitted.

[0186] In this embodiment 11, the secondary batteries 21 to 26 each have six cells. Furthermore, for example, Figure 31 The discharge curve shown in (a) is stored in the correspondence storage unit 51 as a discharge curve representing the initial state. Figure 31 The discharge curve shown in (b) is stored in the corresponding relationship storage unit 51 as a discharge curve representing the case where the self-discharge of one of the cells increases. The capacity estimation unit 64 estimates the battery characteristics based on the specified voltage range Vs. Figure 31 In the case of the discharge curve shown in (a), the cell that does not show an increase in self-discharge is determined in the degradation determination unit 65. On the other hand, the capacity estimation unit 64 estimates the battery characteristics based on the specified voltage range Vs. Figure 31 In the case of the discharge curve shown in (b), the degradation determination unit 65 determines that there is a single cell with an increased self-discharge. Furthermore, in the case of what is presumed to be... Figure 31 In the case of the discharge curve shown in (b), a second lower limit of use Vmin2 can be set in the secondary battery. This second lower limit of use Vmin2 is a higher value than the first lower limit of use Vmin1 when there is no cell with an increased discharge capacity. As a result, it is possible to prevent the cells from over-discharging.

[0187] (Implementation Method 12)

[0188] In this embodiment 12, each of the secondary batteries 21 to 26 comprises six cells. Furthermore, the correspondence storage unit 51 stores a correspondence between the total capacity difference among the cells within the secondary batteries 21 to 26 and the battery characteristics. The total capacity difference among cells refers to the degree of difference in the total capacity of each cell within the plurality of cells included in a secondary battery 21 to 26. In this embodiment 12, as... Figure 32 As shown, the difference in total capacity between individual units is represented by the difference Qmax-min, obtained by subtracting the minimum Qmin from the maximum Qmax among the total capacities of multiple units. Other structures are the same as in Embodiment 1, and the same symbols are used as in Embodiment 1, with their descriptions omitted.

[0189] In this embodiment 12, the capacity estimation unit 64 estimates the difference Qmax-min based on the battery characteristics acquired by the battery characteristic acquisition unit 63 and according to the correspondence stored in the correspondence storage unit 51. Then, the degradation determination unit 65 detects the presence or absence of specific capacity degradation in a single cell based on the estimated difference Qmax-min. For example, if it is determined that the estimated difference Qmax-min is above a predetermined value, it is determined that one of the cells of the secondary batteries 21 to 26 has experienced specific capacity degradation.

[0190] (Implementation Method 13)

[0191] like Figure 33 As shown, in embodiment 13, a resistance estimation unit 641 is included as the estimation unit. The resistance estimation unit 641 estimates the internal resistance of the secondary batteries 21-26 based on their battery characteristics. A correspondence between the internal resistance of the secondary batteries 21-26 and their battery characteristics is stored in the correspondence storage unit 51. The battery characteristic acquisition unit 63 can acquire battery characteristics by performing pulse charge and discharge in a battery stack in which the secondary batteries 21-26 are connected to each other. The voltage range for acquiring battery characteristics can be set to a predetermined voltage range corresponding to a specific SOC range.

[0192] Furthermore, when the temperature and SOC of the secondary batteries 21-26 differ, the battery characteristics can be obtained by acquiring the voltage changes during charging and discharging, or the voltage changes during voltage relaxation after charging and discharging, to estimate the resistance value under the same temperature and SOC conditions. In this case, a correspondence between the internal resistance, temperature, and battery characteristics of the secondary batteries 21-26 is stored in the correspondence storage unit 51. Alternatively, the battery characteristics can be obtained by charging and discharging the secondary batteries 21-26 separately. In this case, it is not necessary to adjust the temperature and SOC to the same conditions, thus shortening the determination time.

[0193] Next, the degradation degree determination method of the degradation degree determination device 1 in this embodiment 13 will be described below. First, in this embodiment 13, with Figure 5 The same applies to the case of Embodiment 1 shown. Figure 34 Steps S1 to S5 are shown. Next, in... Figure 34 In step S77 shown, the internal resistance of the secondary batteries 21-26 is obtained by the resistance estimation unit 641 based on the battery characteristics obtained by the battery characteristic acquisition unit 63 and the correspondence between the internal resistance of the secondary batteries 21-26 and the battery characteristics stored in the correspondence storage unit 51. Subsequently, Figure 34 In step S8 shown, the degradation degree of the secondary batteries 21-26 is determined by the degradation degree determination unit 65 based on the internal resistance estimated by the resistance estimation unit 641. Additionally, with... Figure 5 Similarly, in the case of Embodiment 1 shown, after performing... Figure 34 After steps S9 and S10, in step S113, the charge / discharge control unit 71 charges and discharges the secondary battery whose degradation degree is not determined, and measures the measured value of the internal resistance. Then, similarly to the case of Embodiment 1, in step S12, the acquisition criteria and degradation degree determination criteria are updated. In this Embodiment 13, the same effect as in Embodiment 1 is achieved.

[0194] (Implementation Method 14)

[0195] In the degradation degree determination device 1 of embodiment 14, the negative electrode resistance of the secondary batteries 21 to 26 is estimated by the resistance estimation unit 641, and the degradation degree of the secondary batteries 21 to 26 is determined by the degradation degree determination unit 65.

[0196] Based on the frequency characteristics in the voltage curves of secondary batteries 21-26, the resistance values ​​of the positive electrode, negative electrode, and other battery components in secondary batteries 21-26 can be calculated. Furthermore, in nickel-metal hydride batteries and lithium-ion batteries, the negative electrode resistance is significantly reflected in the high-frequency region of the voltage curve, while the positive electrode resistance is significantly reflected in the low-frequency region. In this embodiment 14, nickel-metal hydride batteries are used as secondary batteries 21-26, and the battery characteristic acquisition unit 63 acquires the voltage curves of a predetermined voltage range in the high-frequency region as battery characteristics. The correspondence storage unit 51 stores in advance the correspondence between the voltage curves in the high-frequency region and the negative electrode resistance as battery characteristics. Other constituent elements are the same as in embodiment 13, and the same symbols are used, with their descriptions omitted.

[0197] Furthermore, among the internal resistances related to the degradation degree of secondary batteries 21-26, the dominant resistance elements differ depending on the degradation mode. First, the internal resistance of the secondary battery module is determined by the relationship between three resistance components: electronic resistance, reactive resistance, and internal mass transfer resistance. The secondary battery module can be considered as a series equivalent circuit of these three resistance components. Typically, electronic resistance is the resistance component that mainly occurs in the time region immediately after a constant current is applied to the battery. Reactive resistance is the resistance component that mainly occurs in the time region after the time region where electronic resistance is generated. Internal mass transfer resistance is the resistance component that occurs in the time region after the time region where a constant current is applied for a long time, mainly occurring after the time region where reactive resistance is generated. Furthermore, the negative electrode reactive resistance-dominated region refers to the time region during discharge where the proportion of negative electrode reactive resistance is the largest among the three resistance components. In this negative electrode reactive resistance-dominated region, the negative electrode reactive resistance dominantly determines the internal resistance of the secondary battery 2. In this embodiment 14, the degradation degree determination unit 65 determines the degradation degree of the secondary batteries 21 to 26 in the negative electrode reaction resistance dominated region based on the negative electrode resistance estimated by the resistance estimation unit 641.

[0198] In the degradation degree determination method of the degradation degree determination device 1 based on this embodiment 14, the same procedure is followed as in embodiment 13. Figure 34 The steps S1 to S5 are shown. Then, in step S77, the negative electrode resistance of the secondary batteries 21 to 26 is estimated by the resistance estimation unit 641 based on the voltage curve obtained by the battery characteristic acquisition unit 63 and the correspondence stored in the correspondence storage unit 51. Then, the degradation degree determination unit 65 determines the degradation degree of the secondary batteries 21 to 26 based on the estimated negative electrode resistance. In addition, with Figure 5 The situation is similar in Implementation Method 1 shown, after... Figure 34 After steps S9 and S10, in step S113, the charge / discharge control unit 71 charges and discharges the secondary battery (whose degradation level is not determined) to measure the actual value of the negative electrode resistance. Then, similarly to Embodiment 1, in step S12, the eligibility determination criteria and degradation level determination criteria are updated. In this Embodiment 14, the same effects as in Embodiment 1 are achieved.

[0199] (Implementation Method 15)

[0200] In the degradation degree determination device 1 of Embodiment 15, the positive electrode resistance of the secondary batteries 21-26 is estimated by the resistance estimation unit 641, and the degradation degree of the secondary batteries 21-26 is determined by the degradation degree determination unit 65. In this Embodiment 15, nickel-metal hydride batteries are used as secondary batteries 21-26, and the battery characteristic acquisition unit 63 acquires voltage curves of a predetermined voltage range in the low-frequency region as battery characteristics. The correspondence between the voltage curves as battery characteristics and the positive electrode resistance is pre-stored in the correspondence storage unit 51. Then, the degradation degree determination unit 65 determines the degradation degree of the secondary batteries 21-26 based on the positive electrode resistance estimated by the resistance estimation unit 641 in the positive electrode reaction resistance dominated region. Other components are the same as in Embodiment 14, and the same symbols are used and their descriptions are omitted.

[0201] In the degradation degree determination method of the degradation degree determination device 1 in this embodiment 15, the same procedure as in embodiment 14 is followed. Figure 34 The steps S1 to S5 are shown. Then, in step S77, the positive electrode resistance of the secondary batteries 21 to 26 is estimated by the resistance estimation unit 641 based on the voltage curve obtained by the battery characteristic acquisition unit 63 and the correspondence stored in the correspondence storage unit 51. Then, the degradation degree determination unit 65 determines the degradation degree of the secondary batteries 21 to 26 based on the estimated positive electrode resistance. In addition, with Figure 5 The situation is similar in Implementation Method 1 shown, after... Figure 34 After steps S9 and S10, in step S113, the charge / discharge control unit 71 charges and discharges the secondary battery (whose degradation level is not determined) to measure the actual value of the positive electrode resistance. Then, similarly to Embodiment 1, in step S12, the eligibility determination criteria and degradation level determination criteria are updated. This Embodiment 15 also achieves the same effect as Embodiment 1.

[0202] This invention is not limited to the above-described embodiments, and can be applied to various embodiments without departing from its spirit.

[0203] While this invention has been described based on embodiments, it should be understood that the invention is not limited to those embodiments or constructions. The invention also includes various modifications and variations within the same scope. Furthermore, various combinations and methods, as well as other combinations and methods that include only one element, more than one element, or less than one element, are also included within the scope and spirit of this invention.

Claims

1. A device for determining the degree of degradation of a secondary battery, the device determining the degree of degradation of the secondary battery, characterized in that, have: A battery information acquisition unit acquires battery information related to the secondary battery. The yes / no determination unit determines the degree of degradation of each secondary battery based on the battery information acquired by the battery information acquisition unit and a pre-prepared yes / no determination criterion. The battery characteristic acquisition unit acquires battery characteristics related to the progression of battery state within a specified voltage range for the secondary battery that is determined by the availability determination unit to be capable of being assessed for degradation. as well as The degradation degree determination unit determines the degradation degree of the secondary battery that is deemed suitable for degradation degree determination based on the battery characteristics acquired by the battery characteristic acquisition unit or battery characteristic-related values ​​calculated based on the battery characteristics. The battery characteristics include at least one of the voltage shift when the secondary battery is discharged to a specified discharge target voltage and the voltage shift after the secondary battery has been discharged to the discharge target voltage and then stopped discharging. The voltage shift is calculated based on at least one of the following: the range capacity of the secondary battery within the voltage range, the ratio of the voltage change of the secondary battery within the voltage range to the capacity change of the secondary battery, the ratio of the voltage change of the secondary battery within the voltage range to the elapsed time, and the ratio of the range capacity of the voltage range to the total discharge capacity when discharged to the target discharge voltage. The yes / no determination unit uses the distance between data calculated based on two or more pre-acquired battery information as the yes / no determination criterion, and makes a yes / no determination based on the comparison result of the battery information correlation value and the yes / no determination criterion. The battery information correlation value is calculated from the battery information obtained by the battery information acquisition unit using a relational formula related to a plurality of pre-set battery information.

2. The degradation determination device for secondary batteries according to claim 1, characterized in that, The voltage shift is calculated based on at least two of the following: the range capacity of the secondary battery in the voltage range, the ratio of the voltage change of the secondary battery in the voltage range to the capacity change of the secondary battery, the ratio of the voltage change of the secondary battery in the voltage range to the elapsed time, and the ratio of the range capacity of the voltage range to the total discharge capacity when discharged to the discharge target voltage.

3. The degradation degree determination device for a secondary battery according to claim 1 or 2, characterized in that, The battery information includes at least one of the battery characteristics and the historical information of the secondary battery.

4. The degradation determination device for a secondary battery according to claim 1 or 2, characterized in that, The battery information includes both the battery characteristics and the historical information of the secondary battery.

5. The degradation determination device for a secondary battery according to claim 1 or 2, characterized in that, The degradation determination unit does not perform degradation determination on secondary batteries that are determined by the permissibility determination unit to be unsuitable for degradation determination.

6. The degradation degree determination device for a secondary battery according to claim 1 or 2, characterized in that, The relational formula related to the pre-set multiple battery information is a relational formula logically derived from the model of the secondary battery to determine the validity criterion.

7. The degradation determination device for a secondary battery according to claim 1 or 2, characterized in that, The voltage range is the range in which the difference in discharge voltage characteristics becomes significant depending on the degree of degradation of the secondary battery.

8. The device for determining the degree of degradation of a secondary battery according to claim 1 or 2, characterized in that, The distance between data points used as the criterion for determining whether a decision is possible includes Mahalanobis distance.

9. A device for determining the degree of degradation of a secondary battery, the device determining the degree of degradation of the secondary battery, characterized in that, have: A battery information acquisition unit acquires battery information related to the secondary battery. The yes / no determination unit determines the degree of degradation of each secondary battery based on the battery information acquired by the battery information acquisition unit and a pre-prepared yes / no determination criterion. The battery characteristic acquisition unit acquires battery characteristics related to the progression of battery state within a specified voltage range for the secondary battery that is determined by the availability determination unit to be capable of being assessed for degradation. as well as The degradation degree determination unit determines the degradation degree of the secondary battery that is deemed suitable for degradation degree determination based on the battery characteristics acquired by the battery characteristic acquisition unit or battery characteristic-related values ​​calculated based on the battery characteristics. The battery characteristics include at least one of the voltage shift when the secondary battery is charged to a specified target charging voltage and the voltage shift after the secondary battery is charged to the target charging voltage and charging is stopped. The voltage shift is calculated based on at least one of the following: the range capacity of the secondary battery within the voltage range, the ratio of the voltage change of the secondary battery within the voltage range to the capacity change of the secondary battery, the ratio of the voltage change of the secondary battery within the voltage range to the elapsed time, and the ratio of the range capacity of the voltage range to the total charging capacity when charged to the target charging voltage. The yes / no determination unit uses the distance between data calculated based on two or more pre-acquired battery information as the yes / no determination criterion, and makes a yes / no determination based on the comparison result of the battery information correlation value and the yes / no determination criterion. The battery information correlation value is calculated from the battery information obtained by the battery information acquisition unit using a relational formula related to a plurality of pre-set battery information.

10. The degradation determination device for a secondary battery according to claim 9, characterized in that, The voltage shift is calculated based on at least two of the following: the range capacity of the secondary battery in the voltage range, the ratio of the voltage change of the secondary battery in the voltage range to the capacity change of the secondary battery, the ratio of the voltage change of the secondary battery in the voltage range to the elapsed time, and the ratio of the range capacity of the voltage range to the total charging capacity when charged to the target charging voltage.

11. The degradation determination device for a secondary battery according to claim 9 or 10, characterized in that, The battery information includes at least one of the battery characteristics and the historical information of the secondary battery.

12. The degradation determination device for a secondary battery according to claim 9 or 10, characterized in that, The battery information includes both the battery characteristics and the historical information of the secondary battery.

13. The degradation determination device for a secondary battery according to claim 9 or 10, characterized in that, The degradation determination unit does not perform degradation determination on secondary batteries that are determined by the permissibility determination unit to be unsuitable for degradation determination.

14. The degradation determination device for a secondary battery according to claim 9 or 10, characterized in that, The relational formula related to the pre-set multiple battery information is a relational formula logically derived from the model of the secondary battery to determine the validity criterion.

15. The degradation determination device for a secondary battery according to claim 9 or 10, characterized in that, The voltage range is the range in which the difference in the charging voltage characteristics becomes significant depending on the degree of degradation of the secondary battery.

16. The degradation degree determination device for a secondary battery according to claim 9 or 10, characterized in that, The distance between data points used as the criterion for determining whether a decision is possible includes Mahalanobis distance.

Images