Deterioration degree determination device for secondary battery

Abstract

The degradation degree determination device (1) includes a charge / discharge control unit (71), a battery characteristic acquisition unit (61), and a determination unit (63). The charge / discharge control unit (71) performs charge / discharge of the battery pack (2) while measuring the voltage of each of the multiple secondary batteries (21-26) to form a battery pack (2). The battery characteristic acquisition unit (61) acquires battery characteristics related to the progression of battery states across a predetermined voltage range for at least a portion of the multiple secondary batteries (21-26). Furthermore, the determination unit (63) determines the degradation degree of at least a portion of the multiple secondary batteries (21-26) based on the battery characteristics or battery characteristic-related values ​​calculated from the battery characteristics.

Description

[0001] Cross-reference of related applications

[0002] This application is based on Japanese Patent Application No. 2020-113172, 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] Conventionally, the degree of degradation of secondary batteries that deteriorate with use is diagnosed. For example, Patent Document 1 discloses a structure for diagnosing the degradation of a battery constituting an energy storage unit installed in a vehicle. In this structure, in the service mode for performing degradation diagnosis, the rechargeable capacity of the battery is determined by discharging the battery until the remaining capacity reaches zero and then charging the battery until it is fully charged, and the battery degradation diagnosis is performed.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2012-16163

[0008] When a battery is composed of multiple secondary cells, the degree of degradation of each secondary cell varies with use. Therefore, even if the degradation of some secondary cells in a battery exceeds a certain threshold, the overall degradation of the battery is still considered high, and it is deemed unusable. Thus, there are cases where only a portion of the secondary cells in a battery deemed unusable exceed the threshold, while the others have lower degradation levels. Therefore, to improve the reuse rate of secondary batteries, the highly degraded secondary cells are removed, and the lower-degraded secondary cells are reassembled into a battery pack for reuse as refurbished products. Therefore, by obtaining the degradation level of each secondary cell constituting the battery pack, the utilization rate of the secondary batteries can be improved.

[0009] In conventional methods, determining the individual degradation level of each of the multiple secondary batteries within a battery pack requires performing the assessment separately after each secondary battery has been removed from the battery pack. Therefore, to determine the degradation level of the multiple secondary batteries in a vehicle battery, the battery must first be removed from the vehicle, and then each secondary battery must be connected to the degradation assessment device and electrical load after removal. This makes the degradation assessment process complex and increases the operational burden. Summary of the Invention

[0010] The present invention provides a secondary battery degradation determination device that can reduce the load of the degradation determination operation of the secondary battery constituting a battery pack.

[0011] One aspect of the present invention relates to a device for determining the degradation degree of a secondary battery, comprising:

[0012] The charge-discharge control unit measures the voltage of each secondary battery while charging and discharging the battery pack in a state where multiple secondary batteries are connected to each other to form a battery pack.

[0013] A battery characteristic acquisition unit acquires battery characteristics related to the progression of battery states over a predetermined voltage range for at least a portion of the plurality of secondary batteries; and

[0014] The determination unit determines the degree of degradation of at least a portion of the plurality of secondary batteries based on the battery characteristics or battery characteristic-related values ​​calculated from the battery characteristics.

[0015] In the aforementioned secondary battery degradation determination device, charging and discharging are performed with multiple secondary batteries connected to each other to form a battery pack. Battery characteristics related to the progression of battery states across a predetermined voltage range are acquired for at least a portion of the secondary batteries. Then, the degradation degree of the at least a portion of the secondary batteries is determined based on these battery characteristics or battery characteristic-related values ​​calculated from them. Therefore, the degradation degree of the at least a portion of the secondary batteries can be determined without removing them from the battery pack. When determining the degradation degree, since the multiple secondary batteries forming the battery pack are already connected to each other, there is no need to remove the secondary batteries from the battery pack and wire each secondary battery to the degradation determination device. Therefore, the operability of determining the degradation degree of secondary batteries can be improved.

[0016] As described above, according to the above method, a secondary battery degradation determination device can be provided that improves operability when determining the degradation degree of secondary batteries constituting a battery pack.

[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 This is a conceptual diagram showing the structure of the battery pack in Implementation Method 1.

[0021] Figure 3 This is a conceptual diagram showing the usage state of the degradation determination device in Implementation 1.

[0022] Figure 4 This is a conceptual diagram illustrating the battery characteristics in Implementation Method 1.

[0023] Figure 5 This is another conceptual diagram illustrating the battery characteristics in Implementation 1.

[0024] Figure 6 This is a flowchart illustrating the method for determining the degree of degradation of the secondary battery in Implementation Method 1.

[0025] Figure 7 This is a flowchart illustrating the manufacturing method of the battery pack in Embodiment 1.

[0026] Figure 8 This is a conceptual diagram representing the battery characteristics in variation mode 1.

[0027] Figure 9 This is a conceptual diagram representing the battery characteristics in variant mode 2.

[0028] Figure 10 This is a conceptual diagram representing the battery characteristics in variation mode 3.

[0029] Figure 11 This is a conceptual diagram showing other usage states of the degradation determination device in Implementation 1.

[0030] Figure 12 This is a flowchart illustrating the method for determining the degree of degradation of the secondary battery in variation mode 4.

[0031] Figure 13 This is a conceptual diagram illustrating the battery characteristics in Implementation Method 2.

[0032] Figure 14 This is a conceptual diagram showing the structure of the degradation determination device in Implementation 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 conceptual diagram illustrating the battery characteristics in Implementation Method 4.

[0035] Figure 17 This is a conceptual diagram representing the structure of the degradation determination device in deformation mode 5.

[0036] Figure 18 This is a conceptual diagram showing the structure of the degradation determination device in Implementation 5.

[0037] Figure 19 This is a conceptual diagram illustrating the battery characteristics in Implementation Method 5.

[0038] Figure 20 This is a conceptual diagram representing the battery characteristics in variation mode 6.

[0039] Figure 21 This is a conceptual diagram representing the battery characteristics in variant 7.

[0040] Figure 22 This is a conceptual diagram representing the SOC-OCV curve of the secondary battery in Implementation Method 6.

[0041] Figure 23 This is a flowchart illustrating the method for determining the degree of degradation of the secondary battery in Implementation Method 6.

[0042] Figure 24 (a) is a conceptual diagram showing the discharge curve of the secondary battery in Implementation Method 6. Figure 24 (b) is a conceptual diagram representing the charging curve of the secondary battery in Implementation 6.

[0043] Figure 25 This is a flowchart illustrating the method for determining the degree of degradation of the secondary battery in Embodiment 7.

[0044] Figure 26 This is a conceptual diagram representing the SOC-OCV curve of the secondary battery in Implementation Method 8.

[0045] Figure 27 This is a flowchart illustrating the method for determining the degree of degradation of the secondary battery in Embodiment 9.

[0046] Figure 28 (a) is a conceptual diagram showing the discharge curve of the secondary battery in embodiment 9. Figure 28 (b) is a conceptual diagram representing another discharge curve of the secondary battery in embodiment 9.

[0047] Figure 29 This is a conceptual diagram representing an example of the presumed result in Implementation 10.

[0048] Figure 30 This is a conceptual diagram showing the structure of the degradation determination device in Implementation 11.

[0049] Figure 31 This is a flowchart illustrating the method for determining the degree of degradation of the secondary battery in Embodiment 11. Detailed Implementation

[0050] (Implementation Method 1)

[0051] use Figures 1 to 7 The implementation method of the above-mentioned secondary battery degradation determination device will be described.

[0052] The secondary battery degradation determination device 1 of this embodiment includes a charge / discharge control unit 71, a battery characteristic acquisition unit 61, and a determination unit 63.

[0053] The charge / discharge control unit 71 performs charge / discharge of the battery pack 2 while measuring the voltage of each of the secondary batteries 21 to 26, in a state where multiple secondary batteries 21 to 26 are connected to each other to form a battery pack 2.

[0054] The battery characteristic acquisition unit 61 acquires battery characteristics related to the progression of battery state across a predetermined voltage range for at least a portion of the plurality of secondary batteries 21 to 26.

[0055] Then, the determination unit 63 determines the degree of degradation of at least a portion of the secondary batteries 21 to 26 based on the battery characteristics or battery characteristic-related values ​​calculated from the battery characteristics.

[0056] The following is a detailed description of the secondary battery degradation determination device 1 of this embodiment.

[0057] Figure 1 The degradation determination device 1 shown can determine the degradation degree of the secondary batteries 21 to 26 constituting the battery pack 2. Here, "secondary battery" refers to a rechargeable battery, including single cells or structures composed of multiple cells. "Battery pack" refers to a structure that forms a battery pack by electrically connecting multiple of the aforementioned secondary batteries. In this embodiment, the type of secondary batteries 21 to 26 is not limited; known secondary batteries such as nickel-metal hydride batteries and lithium-ion batteries can be used, and they can be single cells or multiple cells. In this embodiment, as... Figure 2 As shown in (a), secondary batteries 21 to 26 constitute a secondary battery module that can be individually installed and removed. The number of secondary batteries in the battery pack 2 is not particularly limited; in this embodiment 1, it is six. Furthermore, as... Figure 2 As shown in (b), the secondary batteries 21 to 26 are connected in series. Furthermore, the secondary batteries 21 to 26 constitute a module that can be installed and removed individually, and the modules can also be connected in parallel when the individual cells within the module are connected in parallel with each other.

[0058] 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, and a control unit 7.

[0059] 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 standard voltmeter, such as... Figure 2 As shown in (b), the voltage value of each secondary battery 21 to 26 in the battery pack 2 is detected. The current detection unit 32 is composed of a predetermined ammeter and is connected to the secondary batteries 21 to 26 to obtain 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.

[0060] 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.

[0061] 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 61, which will be described later.

[0062] The total capacity can be defined as the capacity from a fully discharged state to a fully charged state during charging. Alternatively, the total capacity can also be defined as the capacity from a fully charged state to a fully discharged state during discharging. Here, the term "fully discharged state" can refer to a valid fully discharged state defined by the system of the vehicle or similar device equipped with the battery pack 2, or it can refer to a state where the lower limit voltage set by the user using the degradation assessment device 1 has been reached. Similarly, the term "fully charged state" can refer to a valid fully charged state defined by the system of the vehicle or similar device, or it can refer to a state where the upper limit voltage set by the user has been reached.

[0063] In addition, Figure 1 The reference value storage unit 52 shown pre-stores reference values ​​for determining the degree of degradation used in the determination unit 63 described later. These reference values ​​are appropriately set according to the determination method in the determination unit 63. In this embodiment, multiple reference values ​​are set in a manner that allows the degree of degradation to be divided into five levels for determination.

[0064] 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 battery pack 2 by measuring the voltages of the secondary batteries 21 to 26 respectively via the voltage detection unit 31. Therefore, the secondary batteries 21 to 26 constituting the battery pack 2 are simultaneously charged and discharged while the battery pack 2 is in its current state. Thus, as... Figure 3 As shown, the degradation degree of each of the secondary batteries 21 to 26 can be determined while they are still mounted in the vehicle 100 without being removed from the battery pack 2. When determining the degradation degree while the batteries are still mounted in the vehicle 100, the charge / discharge control unit 71 can perform the following: Figure 3 As shown, the secondary batteries 21-26 are discharged via onboard electrical devices 101 such as air conditioning and headlights mounted on the vehicle 100, or forcibly charged via an external charging device 102 connected to the vehicle and based on engine regeneration. Alternatively, service personnel can drive the vehicle 100 brought to the service station, or the secondary batteries 21-26 can be charged and discharged using a chassis dynamometer provided at the service station. Furthermore, the charging and discharging of the battery pack 2 controlled by the charging and discharging control unit 71 includes any one of the following: charging only, discharging only, charging after discharging, and discharging after charging.

[0065] Furthermore, in this embodiment, the charge / discharge control unit 71 can discharge any one of the secondary batteries 21 to 26 constituting the battery pack 2 until a preset discharge target voltage VP is reached, or charge it until a preset charging target voltage is reached. In this embodiment, as... Figure 4 As shown, the charge / discharge control unit 71 continuously discharges the first secondary battery 21 until its voltage reaches the discharge target voltage VP. In this embodiment, the discharge target voltage VP is set outside the normal operating range Vn, and the charge / discharge control unit 71 is configured to allow the secondary batteries 21-26 to deviate from this normal operating range Vn during charge / discharge. Furthermore, the normal operating range refers to the voltage range that is permissible when the secondary batteries 21-26 are in use, and is appropriately preset according to the structure of the secondary batteries 21-26, the structure of the battery pack 2, etc.

[0066] Furthermore, when any one of the secondary batteries 21-26 initially exceeds the discharge target voltage and reaches the critical lower limit of use Vmin, any one of the other secondary batteries 21-26 continues to discharge until the discharge target voltage is reached. For example, as... Figure 5As shown, since the first secondary battery 21 initially exceeds the discharge target voltage VP and reaches the critical lower limit of use Vmin, any one of the other secondary batteries 22 to 26 continues to discharge until it reaches the discharge target voltage. Furthermore, the usable range refers to the voltage range preset in the secondary batteries 21 to 26 that will not cause over-discharge or over-charge. The critical lower limit of use Vmin represents the lower limit of the usable range preset in the secondary batteries 21 to 26.

[0067] Figure 1 The arithmetic unit 6 shown is composed of a defined arithmetic device, including a battery characteristic acquisition unit 61, a capacity estimation unit 62 as an estimation unit, and a determination unit 63. The battery characteristic acquisition unit 61 acquires the battery characteristics of secondary batteries 21-26. The battery characteristics of secondary batteries 21-26 can be, for example, the voltage shift and temperature shift characteristics of secondary batteries 21-26 within a defined voltage range Vs. Furthermore, the battery characteristic acquisition unit 61 can also acquire the absolute value of the acquired values ​​as the battery characteristic. The defined voltage range Vs for acquiring the battery characteristics of secondary batteries 21-26 can be set for each secondary battery 21-26, or can be appropriately changed.

[0068] The states of the secondary batteries 21-26 constituting battery pack 2 do not necessarily need to be equal, and the differences in battery states increase with the use of battery pack 2. Therefore, the voltage shift within the same voltage range also differs from each other depending on the degree of degradation. Furthermore, this battery shift can be calculated based on at least one of, for example, the range capacity of secondary batteries 21-26 within a specified voltage range, the ratio of the voltage change of secondary batteries 21-26 within a specified voltage range to the capacity change of secondary batteries 21-26, and the ratio of the voltage change of secondary batteries 21-26 within a specified voltage range to the elapsed time. The specified voltage range can be defined as a voltage range that represents the correlation between the degree of degradation of secondary batteries 21-26 and the shift in battery states. 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.

[0069] Furthermore, in this embodiment, as Figure 4As shown, among the multiple secondary batteries 21 to 26 constituting the battery pack 2, secondary batteries 21 to 23 are set to a first voltage range Vs1 from voltage V1a to voltage V1b, and secondary batteries 24 to 26 are set to a second voltage range Vs2 from voltage V2a to voltage V2b, which is different from the first voltage range. Furthermore, among the multiple secondary batteries 21 to 26 constituting the battery pack 2, the first secondary battery 21, the second secondary battery 22, and the third secondary battery 23 are set to a common voltage range Vs1, and the fourth secondary battery 24, the fifth secondary battery 25, and the sixth secondary battery 26 are set to a common voltage range Vs2.

[0070] In this embodiment, the discharge voltage characteristic is used as the battery characteristic. The discharge voltage characteristic is calculated based on the voltage shift during the discharge of battery pack 2. The voltage shift during the discharge of battery pack 2 is different for each secondary cell 21 to 26. In this embodiment, as... Figure 4 As shown, when comparing the first secondary battery 21 and the fourth secondary battery 24 among the secondary batteries 21-26, the voltage of the first secondary battery 21 is lower than that of the fourth secondary battery 24 at the start of discharge T0, and at the end of discharge Te, the voltage of the first secondary battery 21 decreases to a value close to the lower limit of use Vmin. On the other hand, the voltage of the fourth secondary battery 24 gradually decreases from the start of discharge T0 to the end of discharge Te, but it is higher than that of the first secondary battery 21 at any time point, and at the end of discharge Te, it also maintains a value that is sufficiently higher than the lower limit of use Vmin.

[0071] And, as Figure 4 As shown, the battery characteristic acquisition unit 61 calculates the first battery characteristic of the first secondary battery 21 within a first voltage range Vs1 from voltage V1a to voltage V1b. On the other hand, in the fourth secondary battery 24, since a portion of the voltage shift within the first voltage range Vs1 is not acquired, the battery characteristic within the first voltage range Vs1 cannot be acquired. Therefore, for the fourth secondary battery 24, the battery characteristic acquisition unit 61 selects a second voltage range Vs2 from voltage V2a to voltage V2b as the range within which voltage characteristics can be acquired from the voltage range acquired until the end of discharge Te, and calculates the second battery characteristic within this second voltage range Vs2.

[0072] The battery characteristic acquisition unit 61 acquires battery characteristics for other secondary batteries 22 and 23 based on the voltage shift in the first voltage range Vs1, just like the first secondary battery 21. For other secondary batteries 25 and 26, it acquires battery characteristics based on the voltage shift in the second voltage range Vs2, just like the fourth secondary battery 24.

[0073] Furthermore, in this embodiment 1, Figure 1 The capacity estimation unit 62 shown estimates the total capacity of the secondary batteries 21 to 26 based on the battery characteristics acquired by the battery characteristic acquisition unit 61. The total capacity can be estimated using prediction models such as regression equations, for example, linear regression, LASSO regression, Ridge regression, decision trees, support vector regression, etc.

[0074] Figure 1 The determination unit 63 shown determines the degree of degradation of secondary batteries 21-26 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 total capacity of secondary batteries 21-26 by the capacity estimation unit 62 is used as the battery characteristic-related value. Therefore, in this embodiment 1, the determination unit 63 determines the degree of degradation of secondary batteries 21-26 based on the estimation result of the capacity estimation unit 62. The determination method can be performed by comparing the estimation result of the capacity estimation unit 62 with the reference values ​​pre-stored in the reference value storage unit 52.

[0075] In addition, such as Figure 5 As with the first secondary battery 21 in the modified form 1 shown, if the voltage is lower than the critical lower limit Vmin from the start of discharge T0 to the end of discharge Te, the first secondary battery 21 cannot be reused. Therefore, the battery characteristics are not obtained and the degree of degradation is not determined. Instead, the individual parts can be recycled by disassembly or the like.

[0076] Furthermore, in the degradation degree determination device 1, for example, Figure 3 As shown, the detection unit 3 and the storage unit 4 can be composed of equipment or devices pre-installed in the vehicle equipped with the battery pack 2, and the storage unit 5, the computing unit 6 and the control unit 7 can be composed of scanning tools 110 provided by service stations that perform inspections and repairs on the vehicle 100.

[0077] The following describes the method for determining the degree of degradation of the degradation degree determination device 1 based on this embodiment.

[0078] First, in this embodiment, in Figure 6 In step S1 shown, as a preparation process, the vehicle equipped with the battery pack 2 is brought to the service station and the vehicle is connected to the scanning tool 110 that constitutes the deterioration determination device 1, which consists of the storage unit 5, the calculation unit 6, and the control unit 7.

[0079] Next, in Figure 6 In step S2, at least one of the secondary batteries 21-26 is discharged until the open-circuit voltage reaches the target discharge voltage VP. This discharges the remaining capacity of each secondary battery 21-26. In this embodiment, as... Figure 4As shown, the first secondary battery 21 continues to discharge until the discharge target voltage is reached. Moreover, in this embodiment, since the secondary batteries 21 to 26 are nickel-metal hydride batteries, there is a possibility of memory effect in these secondary batteries 21 to 26. However, the memory effect is also released simultaneously in the secondary batteries 21 to 26 as they discharge to the discharge target voltage VP or close to the discharge target voltage VP.

[0080] As the remaining capacity is discharged in step S2, in Figure 6 In step S3 shown, the battery characteristics of each secondary battery 21 to 26 are acquired by the battery characteristic acquisition unit 61. In this embodiment, the above-mentioned discharge voltage characteristic is acquired as the battery characteristic.

[0081] In this embodiment, such as Figure 4 As shown, the battery characteristic acquisition unit 61 acquires voltage-time changes as voltage shifts for the secondary batteries 21 to 26. These voltage-time changes represent the relationship between the voltage changes acquired over time from the start of discharge (T0) to the end of discharge (Te). Then, for secondary batteries 21 to 23 of the battery pack 2 that can acquire voltage shifts over the entire first voltage range (Vs1), the battery characteristic acquisition unit 61 acquires discharge voltage characteristics based on the voltage shifts within this first voltage range. On the other hand, for secondary batteries 21 to 26 for which voltage shifts cannot be acquired over the entire first voltage range (Vs1), the battery characteristic acquisition unit 61 acquires discharge voltage characteristics based on the voltage shifts within a second voltage range (Vs2) that is included in the range where voltage shifts can be acquired.

[0082] Furthermore, for secondary batteries 21 to 23, the differential values ​​at specified voltages within the first voltage range Vs1 are calculated respectively. Figure 4 The slope of the tangent line at a specified voltage within the first voltage interval Vs1 in the voltage-time variation curve shown is used as the differential value of the discharge voltage characteristics of secondary batteries 21-23 respectively. Additionally, as... Figure 4 As shown, for secondary batteries 24 to 26, the differential values ​​at specified voltages within the second voltage range Vs2 are calculated respectively. Figure 4 The slope of the tangent at a specified voltage within the second voltage interval Vs2 in the voltage-time variation curve shown is used as the differential value of the discharge voltage characteristics of secondary batteries 24 to 26.

[0083] Furthermore, in this embodiment, the voltage-time change is obtained as a voltage shift, and the differential value at a specified voltage within a specified voltage range Vs1, Vs2 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, i.e., 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 4 The two points in the voltage-time variation of the secondary batteries 21-23 shown can be the start and end times of the voltage interval Vs1, and the two points in the voltage-time variation of the secondary battery modules 24-26 can be the start and end times of the voltage interval Vs2.

[0084] In this embodiment, the voltage-time change is obtained as the voltage shift as the discharge voltage characteristic, and the differential value at a specified voltage within a specified voltage range Vs is used. However, the voltage-capacity change can be obtained instead as the voltage shift, which represents the relationship between the voltage change and the capacity from the capacity Q0 at the start of discharge to the capacity QP1 at the end of discharge. Furthermore, the differential value at a specified voltage within the voltage ranges Vs1 and Vs2, i.e., the slope of the tangent line at a specified voltage in the voltage-capacity change curve, can be calculated, and this differential value can be used as the discharge voltage characteristic of each of the secondary batteries 21 to 26.

[0085] Next, in Figure 6 In step S4, the capacity estimation unit 62 estimates the total capacity, i.e., 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 61. In this embodiment, the capacity estimation unit 62 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, and according to the discharge voltage characteristics, which are battery characteristics acquired by the battery characteristic acquisition unit 61.

[0086] Then, in Figure 6 In step S5 shown, the degree of degradation of the secondary batteries 21 to 26 is determined by the determination unit 63 based on the total capacity estimated by the capacity estimation unit 62.

[0087] In the battery pack 2 installed in the vehicle, based on the individually determined degree of degradation, the secondary batteries 21 to 26 can be appropriately reassembled or replaced to create a refurbished battery pack. In this embodiment, the refurbished product is manufactured as follows.

[0088] First of all, Figure 7In step S10, the secondary batteries are graded according to the degradation degree obtained as described above. In this embodiment, the absolute value of the degradation degree is divided into a predetermined 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. Thus, secondary batteries within the same level have the same degree of degradation. Furthermore, the grading criteria can be appropriately set.

[0089] Then, in Figure 7 In step S11, secondary batteries are removed from the battery pack and sorted according to each grade. Secondary batteries sorted in the same way are also collected from other battery packs. In step S12, secondary batteries are assembled in a desired combination of grades to create a refurbished battery pack. The combination of secondary battery grades can be appropriately set. For example, by assembling battery pack 2 with secondary batteries of the same grade, the difference in deterioration among the secondary batteries in battery pack 2 can be below a predetermined benchmark value. It is not limited to this; battery pack 2 can also be made within a predetermined range of grades, for example, battery packs can be made using secondary batteries of grades A and B. Furthermore, secondary batteries classified as grade E, the lowest grade, can be considered unusable and discarded or disassembled for component recycling. Subsequently, in this embodiment, in... Figure 7 In step S13, the battery pack is recharged. Thus, the secondary battery is ready to be used as a battery pack.

[0090] Next, the effects of the degradation degree determination device 1 in this embodiment will be described in detail.

[0091] In this degradation degree determination device 1, multiple secondary batteries 21-26 are connected to each other to form a battery pack 2. The device performs charging and discharging, and acquires battery characteristics related to the progression of battery states across a predetermined voltage range Vs1, Vs2 for at least a portion of the secondary batteries 21-26. Then, the degradation degree of the at least a portion of the secondary batteries 21-26 is determined based on these battery characteristics or battery characteristic-related values ​​calculated from them. When determining the degradation degree, since the multiple secondary batteries 21-26 forming the battery pack 2 are already connected to each other, there is no need to perform the operation of wiring these secondary batteries 21-26 to the degradation degree determination device in order to remove them from the battery pack 2 and charge / discharge them individually. Therefore, the operational load for determining the degradation degree of the secondary batteries 21-26 can be reduced.

[0092] Furthermore, in this embodiment, the plurality of secondary batteries 21-26 constituting the battery pack 2 includes secondary batteries whose predetermined voltage range for obtaining battery characteristics is set to be different from that of other secondary batteries among the plurality of secondary batteries 21-26. That is, a portion of the plurality of secondary batteries 21-26 are set to a first voltage range Vs1 as the predetermined voltage range, and the other portion are set to a second voltage range Vs2 as the predetermined voltage range. Therefore, since the voltage shift in the first voltage range Vs1 of secondary batteries 24-26 cannot be fully obtained, if the battery shift in the second voltage range Vs2, which is different from the first voltage range Vs1, can be obtained, the degree of degradation can be determined based on the voltage shift. Therefore, it is easy to determine the degree of degradation of each secondary battery 21-26 without removing the secondary batteries 21-26 from the battery pack.

[0093] Furthermore, in this embodiment, the plurality of secondary batteries 21 to 26 constituting the battery pack 2 include secondary batteries with mutually common voltage ranges Vs1 and Vs2 as predetermined voltage ranges for obtaining battery characteristics. That is, among the plurality of secondary batteries 21 to 26, secondary batteries 21 to 23 are set with a first voltage range Vs1 as the common voltage range, and secondary batteries 24 to 26 are set with a second voltage range Vs2 as the common voltage range. As a result, voltage range management becomes easier, and the burden of calculating battery characteristics can be reduced.

[0094] Furthermore, in this embodiment, the charge / discharge control unit 71 is configured to allow the voltage of the secondary batteries 21-26 to deviate from a preset normal operating range when charging and discharging the battery pack 2. Therefore, since a wider voltage range for obtaining battery characteristics can be ensured, the accuracy of degradation determination can be improved.

[0095] Furthermore, in this embodiment, the charge / discharge control unit 71 is configured to allow the voltage of the secondary batteries 21-26 to deviate from a predetermined usable range when charging and discharging the battery pack 2. Therefore, if the secondary batteries 21-26 constituting the battery pack 2 include a secondary battery whose degradation has progressed more significantly than the others, during charging and discharging in the state of the battery pack 2, during the charging and discharging period within the usable range of the deteriorating secondary battery, there may be cases where the voltage shift of the entire predetermined voltage range cannot be fully obtained in the other secondary batteries. Therefore, by allowing a portion of the secondary batteries to deviate from their usable range, the voltage shift of the entire predetermined voltage range can be obtained in the other secondary batteries, improving the accuracy of determining the degradation degree of the other secondary batteries. In addition, since secondary batteries that are charged and discharged outside their usable range cannot be used as secondary batteries, they can be disassembled and their components recycled.

[0096] Furthermore, in this embodiment, the battery pack 2 is for use in a vehicle, and the charge / discharge control unit 71 is configured to perform charge / discharge while the battery pack 2 is mounted in the vehicle. Therefore, when determining the degree of degradation of the secondary batteries 21-26, since it is not necessary to remove the battery pack 2 from the vehicle, operability is improved.

[0097] Alternatively, instead of charging and discharging the battery pack 2 while it is mounted in the vehicle, the battery pack 2 can be removed from the vehicle, and the charging and discharging can be performed by the charging and discharging control unit 71 while maintaining the state of the battery pack 2. In this case, since the battery pack 2 can be wired to the degradation degree determination device 1, the wiring operation time can be reduced compared to the case where the secondary batteries 21 to 26 are removed from the battery pack 2 and wired to the degradation degree determination device 1 separately, thereby improving operability.

[0098] Furthermore, in this embodiment, the charge / discharge control unit 71 is configured to charge and discharge the secondary battery via a device mounted on the vehicle. Therefore, since there is no need to prepare separate charging and discharging devices for the secondary batteries 21-26, the structure of the degradation determination device 1 can be simplified and manufacturing costs reduced.

[0099] Furthermore, although in this embodiment, the capacity estimation unit 62 estimates the total capacity of the secondary batteries 21-26 based on the battery characteristics acquired by the battery characteristic acquisition unit 61, and the determination unit 63 determines the degree of degradation of the secondary batteries 21-26 based on the estimation result, it is also possible to omit the capacity estimation unit 62 from estimating the total capacity, and instead, the determination unit 63 determines the degree of degradation of the secondary batteries 21-26 based on the battery characteristics acquired by the battery characteristic acquisition unit 61. Alternatively, the battery characteristic acquisition unit 61 may acquire the absolute value of the acquired value as the battery characteristic, and the determination unit 63 may determine the degree of degradation based on this absolute value. Alternatively, the determination unit 63 may determine the degree of degradation of the secondary batteries 21-26 based on the difference in battery characteristics acquired by the battery characteristic acquisition unit 61.

[0100] Furthermore, although in this embodiment, the secondary batteries 21 to 26 are classified and assembled into battery pack 2 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 2 in such a way that the difference in the degree of degradation of the secondary batteries 21 to 26 is within a specified range.

[0101] Furthermore, in this embodiment, 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.

[0102] Furthermore, in this embodiment, the discharge voltage characteristics are calculated based on the voltage shift during the discharge of secondary batteries 21-26. However, alternatively, or in addition to this, the discharge voltage characteristics can be calculated based on the voltage shift during voltage relaxation when the voltage of secondary batteries 21-26 returns to the open-circuit voltage after discharge. Figure 8 In the shown variation 1, secondary batteries 21 to 26 each experience voltage relaxation after the end of discharge, Te. Furthermore, in the first secondary battery 21, the differential value of the voltage range Vs1, which includes the voltage range that generates the voltage relaxation, can be calculated based on the voltage shift within that first voltage range to obtain the discharge voltage characteristics, similar to the case in Embodiment 1. Similarly, in the second and third secondary batteries 22 and 23, the discharge voltage characteristics can be obtained based on the voltage shift within the second voltage range Vs2; in the fourth secondary battery 24, the discharge voltage characteristics can be obtained based on the voltage shift within the third voltage range Vs3; and in the fifth and sixth secondary batteries 25 and 26, the discharge voltage characteristics can be obtained based on the voltage shift within the fourth voltage range Vs4. In this case, the same effects as in this embodiment are achieved.

[0103] Furthermore, according to the degradation degree determination device 1 of this embodiment, a battery pack can be provided that includes multiple secondary batteries with a usage history, uses the discharge voltage characteristics of the multiple secondary batteries to estimate the total capacity, and determines the difference in degradation degree of each battery based on the total capacity, which is within a specified range. 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.

[0104] Furthermore, the battery characteristic acquisition unit 61 can also calculate the ratio of the voltage change of the secondary batteries 21 to 26 to the elapsed time within a specified voltage range Vs as the voltage shift, or simultaneously calculate the capacity change of each secondary battery 21 to 26 within the specified voltage range as the range capacity Qp, and use this range capacity Qp as the discharge voltage characteristic. For example, in Figure 4In the embodiment shown, the capacity Qp of secondary batteries 21-23 can be calculated based on the current value flowing through secondary batteries 21-23 in the voltage range Vs1 and the time the current flows, detected by the current value detection unit 32. Similarly, the capacity Qp of secondary batteries 24-26 can be calculated based on the current value flowing through secondary batteries 24-26 in the voltage range Vs1 and the time the current flows, detected by the current value detection unit 32. Furthermore, the respective capacity Qp can be calculated as follows: Figure 9 As shown in the diagram. In this case, the degree of degradation of the secondary batteries 21 to 26 can also be determined with high accuracy and ease based on the capacity Qp of this range, which is a characteristic of the discharge voltage.

[0105] In addition, such as Figure 4 As shown, it can also be calculated. Figure 9 The total charge / discharge capacity Qt shown is the capacity of each of the secondary batteries 21 to 26 during the entire discharge range T0 to Te. A 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. A capacity ratio, which is the ratio of the interval capacity Qp to the specific interval capacity Qt', is then calculated and used as the discharge voltage characteristic. In this case, the degree of degradation of the secondary batteries 21 to 26 can be determined with high accuracy and ease based on this discharge voltage characteristic.

[0106] Alternatively, as a voltage shift, the ratio of the voltage change to the capacity change of the secondary batteries 21-26 within the specified voltage ranges Vs1 and Vs2 can be calculated; that is, the differential value of the voltage within the voltage ranges Vs1 and Vs2 during the voltage-capacity change. This differential value can then be used as the discharge voltage characteristic. In this case, the same effect as in this embodiment is achieved.

[0107] Furthermore, it could also be like this: Figure 10 As shown in Modification 3, the ratio of voltage change to capacity change of secondary batteries 21-26 within a specified voltage range is calculated as a voltage shift; that is, the differential value at the voltage within the voltage range during the voltage-capacity change. This differential value is then used as the discharge voltage characteristic. In Modification 3, a first voltage range Vs1 is defined for secondary batteries 21-23, and a second voltage range Vs2 is defined for secondary batteries 24-26. In this case, the same effect as in the present embodiment is achieved.

[0108] Furthermore, according to the degradation degree determination device 1 of this embodiment, a battery pack can be provided that includes multiple secondary batteries with a usage history. The total capacity of the multiple secondary batteries is estimated using battery characteristics based on voltage shift, and the difference in degradation degree of each battery determined based on this total capacity is within a specified range. The voltage shift is calculated based on at least one of the following: the amount of capacity change of the secondary batteries in a specified voltage range Vs1, Vs2; the ratio of the voltage change of the secondary batteries in voltage range Vs1, Vs2 to the capacity change of the secondary batteries; and the ratio of the voltage change of secondary batteries 21 to 26 in voltage range Vs1, Vs2 to the elapsed time. 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 refurbished battery pack can be improved.

[0109] Furthermore, in this embodiment, the battery characteristics are calculated and obtained in the battery characteristic acquisition unit 61 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 61 via the external input unit, thereby obtaining the battery characteristics.

[0110] Furthermore, although the storage unit 5, the calculation unit 6, and the control unit 7 of the degradation degree determination device 1 in this embodiment are provided in the scanning tool 110 provided at a service station for vehicles, they can also be replaced by other components, such as... Figure 11 As shown, at least one of the storage unit 5, the arithmetic unit 6, and the control unit 7 in the degradation degree determination device 1 is installed on an external server 120 or the like, and it is configured by connecting the scanning tool 110 to the external server via a network, or by utilizing a cloud service 130 via the Internet. The scanning tool 110 acts as a client installed at a service station or the like and has communication capabilities. Alternatively, the storage unit 5, the arithmetic unit 6, and the control unit 7 of the degradation degree determination device 1 may be installed on an external server, and the degradation degree determination device 1 may be configured by providing communication capabilities to the vehicle and enabling communication with the external server via the cloud service 130. Furthermore, when degradation degree determination is performed using the cloud service 130, display units 111 and 103 are provided on the scanning tool 110 and the vehicle 100, and the diagnostic results and the actions to be taken based on the diagnostic results can be displayed on the display units.

[0111] Furthermore, in the degradation degree determination performed by the degradation degree determination device 1 based on this embodiment, such as Figure 12As shown in variant 4, after the preparation step S1, in step S20, temperature adjustment can be performed to control the temperature of the secondary batteries 21-26 to a predetermined temperature. This temperature adjustment can control the temperature of the room where the vehicle containing the battery pack 2 is stored, or it can use the vehicle's cabin air conditioner to control the temperature of the vehicle containing the battery pack 2. By adjusting the temperature and stopping the secondary batteries 21-26, the temperature of the secondary batteries 21-26 can be set to a preset temperature. Furthermore, multiple temperatures can be set as preset temperatures.

[0112] In this variation 4, the temperature of the battery pack 2 can be detected by a temperature sensor (not shown) installed on the battery pack 2. Furthermore, if a temperature sensor is installed for each of the secondary batteries 21-26, the temperature detected by each temperature sensor is taken as the temperature of the secondary battery 21-26. However, even without a temperature sensor for each of the secondary batteries 21-26, the temperature of each secondary battery 21-26 can be estimated based on the temperature detected by the temperature sensor, taking into account the structure of the battery pack 2, the configuration of the secondary batteries 21-26, etc. This temperature estimation can be performed using logically derived formulas for estimating the secondary battery temperature, mapping the detected temperature to the secondary battery temperature based on a model of the battery pack, etc. Figure 12 After step S20 as shown, the same procedure is performed. Figure 6 S2 to S5. According to this determination method, since the temperature of the secondary battery 21 to 26 can be set to a preset temperature for the determination of the degree of degradation, the determination accuracy can be improved.

[0113] In this embodiment, such as Figure 4 As shown, the initial voltage of secondary batteries 21-26, which is the voltage at the start of discharge T0, deviates. However, when secondary batteries 21-26 are lithium-ion batteries, equalization can be performed to make the initial voltages of secondary batteries 21-26 equal before determining the degree of degradation. This equalization can be performed by charging and discharging through the state of any of the secondary batteries 21-26 in the battery pack 2. By performing this equalization, the voltage shift of secondary batteries 21-26 can be easily detected within a common voltage range, thus improving the accuracy of the determination.

[0114] As described above, according to this method, 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 2.

[0115] (Implementation Method 2)

[0116] In Embodiment 1 described above, discharge voltage characteristics were used as battery characteristics; however, in Embodiment 2, in... Figure 13 After the discharge is completed, charging is performed from the start of charging (T1) to the end of charging (Te). Furthermore, as battery characteristics, the discharge voltage characteristics of Embodiment 1 and the charging voltage characteristics based on the voltage shift of one of the secondary batteries 21 to 26 until it is charged to a predetermined charging target voltage (VQ) are obtained. The charging target voltage (VQ) is not particularly limited, but in this embodiment, it is set to a value within the commonly used range (Vn).

[0117] Then, as Figure 13 As shown, for secondary batteries 21-23 among the multiple secondary batteries 21-26, a first voltage range Vs1 is set as a predetermined voltage range for obtaining voltage shifts, and the battery characteristic acquisition unit 61 acquires a first charging voltage characteristic as a battery characteristic based on this. On the other hand, for the other secondary batteries 24-26, since a portion of the voltage shift of the first voltage range Vs1 is not acquired, a second voltage range Vs2 is selected instead as the range from the start of charging T1 to the end of charging Te to acquire battery characteristics, and the battery characteristic acquisition unit 61 acquires a second charging voltage characteristic as a battery characteristic based on this. Furthermore, the charging voltage characteristic as a battery characteristic in this embodiment can be calculated in the same way as the discharge voltage characteristic in Embodiment 1 and its various modifications. Other constituent elements are the same as in Embodiment 1, and the same reference numerals as in Embodiment 1 are used in this embodiment, and their descriptions are omitted.

[0118] Furthermore, the charging voltage characteristic can also be calculated similarly to the discharge voltage characteristic in Embodiment 1 described above, as the ratio of the voltage change between the start and end times of a specified voltage range Vs1 and Vs2, or the range capacity within voltage range Vs1 and Vs2, or the ratio of the range capacity to the total charge / discharge capacity, which is the capacity of the entire range during charging. Alternatively, instead of the total charge / discharge capacity, a specific range capacity can be calculated as the capacity of a specific voltage range that includes the voltage range used to calculate the battery characteristics, and the ratio of the range capacity to that specific range capacity can be calculated, and this ratio can be used as the charging voltage characteristic.

[0119] Furthermore, in this embodiment 2, the battery characteristic acquisition unit 61 acquires both the discharge voltage characteristic and the charging voltage characteristic, and the capacity estimation unit 62 estimates the total capacity of the secondary batteries 21 to 26 based on this. Therefore, the degree of degradation of the secondary batteries 21 to 26 can be determined with even higher accuracy.

[0120] Furthermore, when using the degradation degree determination device 1 of this embodiment 2 to manufacture refurbished battery packs, since each secondary battery 2 is charged before being assembled into battery pack 2, it is not necessary to... Figure 7 The battery pack is recharged in step S13.

[0121] In addition, in this embodiment 2, the battery characteristic acquisition unit 61 acquires the discharge voltage characteristic and then the charging voltage characteristic after the secondary batteries 21 to 26 are discharged and then charged. However, it is not limited to this. It is also possible to acquire the discharge voltage characteristic after the secondary batteries 21 to 26 are charged and then discharged.

[0122] Furthermore, in this embodiment 2, the battery characteristic acquisition unit 61 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 determination 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 determination accuracy. However, when the charging voltage characteristic is acquired only after the remaining capacity has been discharged, in the secondary batteries 21 to 26 that have been discharged to a voltage close to the discharge target voltage VP, the charging voltage characteristic is acquired after the memory effect has been eliminated. Therefore, the influence of the memory effect is less, and the determination accuracy can be expected to be improved.

[0123] Furthermore, the charging voltage characteristics in Embodiment 2 can also be calculated based on the voltage shift during voltage relaxation when the voltage returns to the open-circuit voltage after charging stops, similar to the discharging voltage characteristics in Embodiment 1. In this case, it also achieves the same effect as in this embodiment.

[0124] Furthermore, in this embodiment 2, similarly to the variation in embodiment 1, the capacity estimation unit 62 may not estimate the total capacity, and the determination unit 63 may determine the degree of degradation of the secondary batteries 21-26 based on the battery characteristics acquired by the battery characteristic acquisition unit 61. Alternatively, the battery characteristic acquisition unit 61 may acquire the absolute value of the acquired value as the battery characteristic, and the determination unit 63 may determine the degree of degradation based on this absolute value. Alternatively, the determination unit 63 may determine the degree of degradation of the secondary batteries 21-26 based on the difference in battery characteristics acquired by the battery characteristic acquisition unit 61. Alternatively, the secondary batteries 21-26 may be classified and assembled into battery pack 2 in such a way that the difference in the degree of degradation of the secondary batteries 21-26 is within a specified range.

[0125] (Implementation Method 3)

[0126] In the degradation degree determination device 1 of this embodiment 3, in addition to the structure of embodiment 1, such as Figure 14 As shown, the calculation unit 6 includes an impedance characteristic correlation value acquisition unit 64. The impedance characteristic correlation value acquisition unit 64 acquires the impedance characteristic correlation values ​​of the secondary batteries 21-26 based on the detection values ​​of the voltage detection unit 31 and the current detection unit 32, through DC-IR measurement and low-frequency AC-IR measurement. 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.

[0127] In this third embodiment, the battery characteristic acquisition unit 61 acquires characteristics in the same manner as in the first embodiment. Figure 4 The discharge voltage characteristics are shown within the specified voltage ranges Vs1 and Vs2. Furthermore, the impedance characteristic correlation value acquisition unit 64 acquires the impedance characteristic correlation values ​​of the secondary batteries 21 to 26 at the point Te at the end of discharge.

[0128] Furthermore, the correspondence storage unit 51 pre-stores the correspondence between impedance characteristic values ​​and total capacity. This correspondence can be generated by using machine learning of the secondary battery used for testing, or based on measured values ​​obtained from accelerated degradation tests using the secondary battery used for testing, or by logically deriving a calculation formula for the correspondence between impedance characteristic values ​​and total capacity at a specified voltage using a model of the secondary battery.

[0129] In this embodiment 3, Figure 14 The capacity estimation unit 62 shown estimates the total capacity of secondary batteries 21-26 based on the discharge voltage characteristic obtained by the battery characteristic acquisition unit 61 and the impedance characteristic correlation value obtained by the impedance characteristic correlation value acquisition unit 64. The determination unit 63, similar to that in Embodiment 1, determines the degree of degradation of secondary batteries 21-26 based on the estimation result of the capacity estimation unit 62. According to this Embodiment 3, since the total capacity is estimated based on the discharge voltage characteristic and impedance characteristic correlation value, the determination accuracy can be further improved.

[0130] Furthermore, in this embodiment, the timing at which the impedance characteristic correlation value acquisition unit 64 acquires the impedance characteristic correlation value is not particularly limited. For example, in Embodiment 2, when the battery characteristic acquisition unit 61 acquires the charging voltage characteristic, the timing is when the charging ends.

[0131] Furthermore, according to the degradation degree determination device 1 of this embodiment 3, a battery pack 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 characteristic correlation values ​​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.

[0132] (Implementation Method 4)

[0133] In this embodiment 4, apart from the structure of embodiment 1, such as Figure 15 As shown, it also includes an initial voltage acquisition unit 65. (As shown...) Figure 16 As shown, the initial voltage acquisition unit 65 acquires the initial voltages VI1 to VI6 of the secondary batteries 21 to 26 at the start of discharge T0, respectively. Furthermore, the correspondence storage unit 51 stores in advance the correspondence between the initial voltage values, battery characteristics, and total capacity. 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.

[0134] According to the degradation degree determination device 1 of this embodiment 4, the degradation degree of secondary batteries 21 to 26 is determined by considering the initial voltage in addition to battery characteristics, thus further improving the determination accuracy 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 65.

[0135] Furthermore, according to the degradation degree determination device 1 of this embodiment 4, a battery pack 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. This total capacity is estimated using an initial voltage and battery characteristics, where the initial voltage is the open-circuit voltage of the secondary battery at the time the battery characteristics are first acquired. 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.

[0136] Furthermore, in this embodiment 4, similar to the variation of embodiment 1, the estimation of the total capacity based on the capacity estimation unit 62 is not performed, and the determination unit 63 determines the degree of degradation of the secondary batteries 21 to 26 based on the battery characteristics and initial voltage obtained by the battery characteristic acquisition unit 61. Alternatively, the determination unit 63 determines the degree of degradation of the secondary batteries 21 to 26 based on the battery characteristics and initial voltage obtained by the battery characteristic acquisition unit 61. Alternatively, the absolute value of the values ​​obtained by the battery characteristic acquisition unit 61 can be used as the battery characteristic, and the determination unit 63 can determine the degree of degradation based on this absolute value. Alternatively, the determination unit 63 can determine the degree of degradation of the secondary batteries 21 to 26 based on the difference between the battery characteristics obtained by the battery characteristic acquisition unit 61. Alternatively, the secondary batteries can be classified and assembled into battery packs in a manner where the degree of degradation of the secondary batteries is within a specified range as the difference between the degree of degradation and the degree of degradation.

[0137] Alternatively, as another variation 5, it could also be, for example... Figure 17 As shown, the arithmetic unit 6 includes an internal resistance acquisition unit 66 for acquiring the internal resistance of the secondary battery 21, 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 66, the internal resistance can be calculated based on the measured voltage (which is the voltage value detected by the voltage value detection unit 31), the open-circuit voltage of the secondary batteries 21-26, and the current flowing through the secondary batteries 21-26. Furthermore, the open-circuit voltage of the secondary batteries 21-26 can be estimated at each time interval using a mapping representing the correspondence between the remaining discharge capacity and the initial voltage of the secondary batteries 21-26. Additionally, the internal resistance can also be obtained using a logically derived formula for estimating the internal resistance of the secondary battery. According to the degradation degree determination device 1 of this modified embodiment 5, the degradation degree of the 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.

[0138] In addition to battery characteristics, this modified method 5 also obtains internal resistance to determine the degree of degradation. However, instead, the change in internal resistance based on voltage shift within a specified voltage range can also be obtained as a battery characteristic.

[0139] (Implementation Method 5)

[0140] like Figure 18 As shown, the degradation degree determination device 1 of this embodiment 5, in addition to Figure 1 In addition to the structure shown in Embodiment 1, the battery pack 2 includes a temperature detection unit 33 and secondary batteries 21 and 22. Figure 19 of (a), Figure 19As shown in (b), the temperature detection unit 33 acquires the temperature of the secondary batteries 21 and 22 during charging and discharging. Furthermore, in the above-described embodiment 1, the battery characteristic acquisition unit 61 is configured to acquire the discharge voltage characteristics of the secondary batteries 21 and 22 based on the voltage shift within a predetermined voltage range Vs as battery characteristics. However, in this embodiment 5, instead, as shown in (b), the temperature detection unit 33 acquires the temperature of the secondary batteries 21 and 22 during charging and discharging. Figure 19 As shown in (a), the battery characteristic acquisition unit 61 acquires the temperature characteristics of the secondary batteries 21 and 22 based on the temperature shift within predetermined voltage ranges VsA and VsB as battery characteristics. In this embodiment 5, voltage range VsA represents the voltage range from voltage V1 to voltage V2, and voltage range VsB represents the voltage range from voltage V3 to voltage V4.

[0141] Furthermore, in this embodiment, as Figure 19 of (a), Figure 19 As shown in (b), the first secondary battery 21 has a first discharge temperature characteristic TA1 corresponding to the voltage range VsA and a first charging temperature characteristic TB1 corresponding to the voltage range VsB. Similarly, the second secondary battery 22 has a second discharge temperature characteristic TA2 corresponding to the voltage range VsA and a second charging temperature characteristic TB2 corresponding to the voltage range VsB. Other structures are the same as in Embodiment 1; the same symbols are used for structures identical to those in Embodiment 1, and their descriptions are omitted. Furthermore, the voltage range VsA is the range where the difference in discharge voltage characteristics becomes significant depending on the degree of degradation of the secondary batteries 21 and 22, and the voltage range VsB is the range where the difference in charging voltage characteristics becomes significant depending on the degree of degradation of the secondary batteries 21 and 22.

[0142] Although secondary batteries 21 and 22 are assembled in the same battery pack 2, their temperature changes during charging and discharging can exhibit different behaviors due to factors such as the configuration of the secondary batteries 21 and 22 and the temperature environment. In this embodiment 5, as... Figure 19 As shown in (b), the temperature shifts in the first secondary battery module 21 and the second secondary battery module 22 converge within the measured room temperature setting range Tn, but exhibit slightly different behaviors. Furthermore, in this embodiment 5, the battery characteristic acquisition unit 61 acquires discharge temperature characteristics TA1 and TA2 (discharge temperature characteristics) and charging temperature characteristics TB1 and TB2 (charging temperature characteristics) based on the battery temperatures detected by the temperature detection unit 33 in both a predetermined voltage range VsA during discharge and a predetermined voltage range VsB during charging after discharge. Then, the capacity estimation unit 62 estimates the total capacity of each secondary battery 21 and 22 based on the two temperature characteristics, and the determination unit 63 determines the degree of degradation.

[0143] The temperature characteristics acquired by the battery characteristic acquisition unit 61 can be set to the differential value of the temperature change at a specified voltage in the specified voltage range VsA, VsB, or the ratio of the temperature change between two points in the specified voltage range VsA, VsB, or the ratio of the temperature change of the secondary batteries 21, 22 in the voltage range VsA, VsB to the capacity change of the secondary batteries 21, 22.

[0144] In this fifth embodiment, the same effect as in the first embodiment can be achieved. Furthermore, in this fifth embodiment, 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.

[0145] Furthermore, according to the degradation degree determination device 1 of this embodiment 5, a battery pack 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 the total capacity estimated from the battery characteristics used, 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 2 becomes smaller, the quality of the battery pack as a refurbished product can be improved.

[0146] Furthermore, in this embodiment 5, similarly to a variation of embodiment 1, the estimation of the total capacity based on the capacity estimation unit 62 is not performed, and the determination unit 63 determines the degree of degradation of the secondary batteries 21 and 22 based on the temperature characteristics acquired by the battery characteristic acquisition unit 61. Alternatively, the absolute value of the acquired value obtained by the battery characteristic acquisition unit 61 can be used as the temperature characteristic, and the determination unit 63 can determine the degree of degradation based on this absolute value. Alternatively, the determination unit 63 can determine the degree of degradation of the secondary batteries based on the difference in temperature characteristics acquired by the battery characteristic acquisition unit 61. Alternatively, the secondary batteries can be classified and assembled into battery packs in a manner where the difference in the degree of degradation of the secondary batteries is within a specified range.

[0147] In this embodiment 5, as Figure 19 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 VsB within the normal operating range Vn. However, this can be replaced by, as shown in... Figure 20 As shown in variation 6 of (a), the temperature characteristics during charging are obtained when the target charging voltage VQ exceeds the normal operating range Vn and has a specified voltage range VsB in the region exceeding the normal operating range Vn. In this case, as... Figure 20 As shown in (b), the temperature of secondary batteries 21 and 22 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 6, the voltage of secondary batteries 21 and 22 is returned to the normal operating range Vn after being charged to the target charging voltage VQ.

[0148] In addition, in variant 6, 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 21 As shown in variant 7, charging is performed before discharging, without first discharging. In this case, the battery characteristic acquisition unit 61 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.

[0149] (Implementation Method 6)

[0150] In Embodiment 1 described above, the capacity estimation unit 62, 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 61. However, it is not limited to this; the capacity estimation unit 62 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 6, the capacity estimation unit 62 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 22 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.

[0151] Next, the method for determining the degree of degradation of the degradation degree determination device 1 in Embodiment 6 will be described below. Furthermore, regarding... Figure 6The steps in the illustrated embodiment 1 are the same, with the same symbols used and their descriptions omitted.

[0152] First, in this implementation method 6, with Figure 6 Similarly, in the case of Implementation Method 1 shown, the following is performed: Figure 23 The steps S1 to S3 are shown. Therefore, as... Figure 24 As shown in (a), the battery characteristic acquisition unit 61 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.

[0153] Next, in Figure 23 In step S40 shown, the capacity estimation unit 62 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 61. Subsequently, Figure 23 In step S5 shown, the degree of degradation of the secondary batteries 21 to 26 is determined by the determination unit 63 based on the positive electrode capacity Qc estimated by the capacity estimation unit 62.

[0154] In this embodiment 6, it also achieves the same effect as in embodiment 1. Furthermore, in this embodiment 6, the battery characteristic acquisition unit 61 acquires... Figure 24 The discharge curve shown in (a) can be obtained by alternative methods. Figure 24 The charging curve shown in (b) is as follows. In this case, it also has the same effect as in embodiment 1.

[0155] (Implementation Method 7)

[0156] In Embodiment 6 described above, the capacity estimation unit 62 estimates the positive electrode capacity Qc. However, in Embodiment 7, instead, the capacity estimation unit 62 estimates the negative electrode capacity QA. That is, in Embodiment 7, as... Figure 25 As shown, in step S41, based on Figure 22 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 7, it achieves the same effect as in embodiment 1.

[0157] (Implementation Method 8)

[0158] In this embodiment 8, the capacity estimation unit 62 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.

[0159] For example, in the case where secondary batteries 21-26 are composed of nickel-metal hydride batteries, such as Figure 26 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 26 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.

[0160] In this embodiment 8, based on Figure 26 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.

[0161] The degradation degree determination method of the degradation degree determination device 1 in this embodiment 8 is performed in the same way as in embodiment 6 described above, however, as Figure 27 As shown, in step S3, the battery characteristic acquisition unit 61 acquires the discharge curve of a predetermined voltage range Vs corresponding to the low SOC range of the battery as the battery characteristic. Then, in step S42, based on the correspondence between the battery characteristics calculated from the discharge curve and the offset Qx, the offset Qx of the secondary batteries 21 to 26 is estimated. This offset Qx is the offset of the relative relationship between the negative electrode SOC and the positive electrode SOC stored in the correspondence storage unit 51. Subsequently, in... Figure 27 In step S5, the degradation degree of secondary batteries 21-26 is determined by the determination unit 63 based on the offset Qx estimated by the capacity estimation unit 62. In this embodiment, it achieves the same effect as in embodiment 1. Furthermore, in this embodiment 8, battery characteristics are obtained from the low SOC range, but they could also be obtained from the high SOC range. Additionally, in this embodiment 8, the discharge curve is obtained as the battery characteristic, but the charging curve could also be obtained as the battery characteristic.

[0162] (Implementation Method 9)

[0163] In this embodiment 9, 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 62 estimates the change in discharge capacity in the charge-discharge curve within a specified voltage range Vs. The determination unit 63 detects whether the self-discharge of a single cell has increased based on the estimation result as the degree of degradation. In this embodiment 9, the other structures are the same as in embodiment 1, and the same symbols as in embodiment 1 are used, and their descriptions are omitted.

[0164] In this embodiment 9, the secondary batteries 21 to 26 each have six cells. Furthermore, for example, Figure 28 The discharge curve shown in (a) is stored in the correspondence storage unit 51 as a discharge curve representing the initial state. Figure 28 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 62 estimates the battery characteristics based on the specified voltage range Vs. Figure 28 In the case of the discharge curve shown in (a), the determination unit 63 determines that there is no cell with an increased self-discharge. On the other hand, the capacity estimation unit 62 estimates the battery characteristics based on the specified voltage range Vs. Figure 28 In the case of the discharge curve shown in (b), the determination unit 63 determines that there is a single cell with an increased self-discharge. Furthermore, in the case of presumed... Figure 28 In the case of the discharge curve shown in (b), a second lower limit of use, Vmin2, can be set in the secondary battery module. This second lower limit of use, Vmin2, is a higher value than the first lower limit of use, Vmin1, in the case where there is no cell with an increased discharge capacity. As a result, it is possible to prevent the cells from over-discharging.

[0165] (Implementation Method 10)

[0166] In this embodiment 10, 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 in 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 10, as... Figure 29 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.

[0167] In this embodiment 10, the capacity estimation unit 62 estimates the difference Qmax-min based on the battery characteristics acquired by the battery characteristic acquisition unit 61 and the correspondence stored in the correspondence storage unit 51. Then, the determination unit 63 detects whether there is 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 a specific capacity degradation has occurred in one of the cells of the secondary battery module.

[0168] (Implementation Method 11)

[0169] like Figure 30 As shown, in Embodiment 11, a resistance estimation unit 621 is included as the estimation unit. The resistance estimation unit 621 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 61 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.

[0170] 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.

[0171] Next, the degradation degree determination method of the degradation degree determination device 1 in this embodiment 11 will be described below. First, in this embodiment 11, with Figure 6 The same applies to the case of Embodiment 1 shown. Figure 31 Steps S1 to S3 are shown. Next, in... Figure 31 In step S43 shown, the internal resistance of the secondary batteries 21-26 is obtained by the resistance estimation unit 621 based on the battery characteristics obtained by the battery characteristic acquisition unit 61 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 31In step S5 shown, the degree of degradation of the secondary batteries 21 to 26 is determined by the determination unit 63 based on the internal resistance estimated by the resistance estimation unit 621. In this embodiment 11, it also has the same effect as in embodiment 1.

[0172] (Implementation Method 12)

[0173] In the degradation degree determination device 1 of embodiment 12, the negative electrode resistance of the secondary batteries 21 to 26 is estimated by the resistance estimation unit 621, and the degradation degree of the secondary batteries 21 to 26 is determined by the determination unit 63.

[0174] 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 12, nickel-metal hydride batteries are used as secondary batteries 21-26, and the battery characteristic acquisition unit 61 acquires the voltage curves of a predetermined voltage range in the high-frequency region as battery characteristics. The correspondence storage unit 51 pre-stores 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 11, and the same symbols are used, with their descriptions omitted.

[0175] 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 a secondary battery is determined by the relationship between three resistance components: electronic resistance, reactive resistance, and internal mass transfer resistance. A secondary battery 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 occurs. Internal mass transfer resistance is the resistance component that occurs in the time region after the time region where reactive resistance occurs when a constant current is applied for a long time. Furthermore, the region dominated by negative electrode reactive resistance 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 region dominated by negative electrode reactive resistance, the negative electrode reactive resistance dominantly determines the internal resistance of secondary battery 2. In this embodiment 12, the determination unit 63 determines the degree of degradation 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 621.

[0176] In the degradation degree determination method of the degradation degree determination device 1 based on this embodiment 12, the same procedure is followed as in embodiment 11. Figure 31The steps S1 to S3 are shown. Then, in step S43, the negative electrode resistance of the secondary batteries 21 to 26 is estimated by the resistance estimation unit 621 based on the voltage curve obtained by the battery characteristic acquisition unit 61 and the correspondence stored in the correspondence storage unit 51. Then, the determination unit 63 determines the degree of degradation of the secondary batteries 21 to 26 based on the estimated negative electrode resistance. In this embodiment 12, the same effect as in embodiment 1 is achieved.

[0177] (Implementation Method 13)

[0178] In the degradation degree determination device 1 of Embodiment 13, the positive electrode resistance of the secondary batteries 21-26 is estimated by the resistance estimation unit 621, and the degradation degree of the secondary batteries 21-26 is determined by the determination unit 63. In this Embodiment 13, nickel-metal hydride batteries are used as secondary batteries 21-26, and the battery characteristic acquisition unit 61 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 stored in advance in the correspondence storage unit 51. Then, the determination unit 63 determines the degradation degree of the secondary batteries 21-26 based on the positive electrode resistance estimated by the resistance estimation unit 621 in the positive electrode reaction resistance dominated region. Other components are the same as in Embodiment 12, and the same symbols are used and their descriptions are omitted.

[0179] In the degradation degree determination method of the degradation degree determination device 1 in this embodiment 13, the same procedure as in embodiment 12 is followed. Figure 31 The steps S1 to S3 are shown. Then, in step S43, the positive electrode resistance of the secondary batteries 21 to 26 is estimated by the resistance estimation unit 621 based on the voltage curve obtained by the battery characteristic acquisition unit 61 and the correspondence stored in the correspondence storage unit 51. Then, the determination unit 63 determines the degree of degradation of the secondary batteries 21 to 26 based on the estimated positive electrode resistance. In this embodiment 13, the same effect as in embodiment 1 is achieved.

[0180] This invention is not limited to the above-described embodiments, and can be applied to various embodiments without departing from its spirit.

[0181] 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 degradation degree of a secondary battery, characterized in that, have: The charge-discharge control unit measures the voltage of each secondary battery while charging and discharging the battery pack in a state where multiple secondary batteries are connected to each other to form a battery pack. A battery characteristic acquisition unit acquires battery characteristics related to the progression of battery states over a specified voltage range for at least a portion of the plurality of secondary batteries. as well as The determination unit determines the degree of degradation of at least a portion of the plurality of secondary batteries based on the battery characteristics or battery characteristic-related values ​​calculated from the battery characteristics. The charge / discharge control unit is configured to allow, during the charging and discharging of the battery pack, to either discharge such that the voltage of at least one of the secondary batteries reaches a predetermined discharge target voltage outside the predetermined normal operating range, thus moving it out of the normal operating range, or charge such that the voltage of at least one of the secondary batteries reaches a predetermined charging target voltage outside the normal operating range, thus moving it out of the normal operating range.

2. The degradation determination device for secondary batteries according to claim 1, characterized in that, The plurality of secondary batteries constituting the battery pack include secondary batteries whose voltage range for obtaining the battery characteristics is set to be different from that of other secondary batteries in the plurality of secondary batteries.

3. The degradation determination device for secondary batteries according to claim 2, characterized in that, The plurality of secondary cells constituting the battery pack include secondary cells that have been configured with a common voltage range as a predetermined voltage range for obtaining the characteristics of the battery.

4. The degradation determination device for secondary batteries according to claim 1, characterized in that, The charge / discharge control unit is configured to allow the voltage of the secondary battery to deviate from a preset usable range when the battery pack is being charged or discharged.

5. The degradation determination device for a secondary battery according to claim 1, characterized in that, The battery characteristic acquisition unit, the determination unit, and the charge / discharge control unit are located in the cloud. The battery pack is configured to connect to the cloud via a scanning tool with communication capabilities.

6. The device for determining the degree of degradation of a secondary battery according to any one of claims 1 to 5, characterized in that, The battery pack is for use in a vehicle, and the charge / discharge control unit is configured to perform the charge / discharge while the battery pack is mounted in the vehicle.

7. The degradation determination device for a secondary battery according to claim 6, characterized in that, The charge / discharge control unit is configured to charge and discharge the secondary battery via a device mounted on the vehicle.

8. A device for determining the degradation degree of a secondary battery, characterized in that, have: The charge-discharge control unit measures the voltage of each secondary battery while charging and discharging the battery pack in a state where multiple secondary batteries are connected to each other to form a battery pack. A battery characteristic acquisition unit acquires battery characteristics related to the progression of battery states over a specified voltage range for at least a portion of the plurality of secondary batteries. as well as The determination unit determines the degree of degradation of at least a portion of the plurality of secondary batteries based on the battery characteristics or battery characteristic-related values ​​calculated from the battery characteristics. The specified voltage range is defined as a first voltage range and a second voltage range that is different from the first voltage range. The plurality of secondary batteries constituting the battery pack include a secondary battery for obtaining the battery characteristics with a predetermined voltage range set to a first voltage range and a secondary battery with the predetermined voltage range set to a second voltage range.

9. The degradation determination device for a secondary battery according to claim 8, characterized in that, The plurality of secondary cells constituting the battery pack include secondary cells that have been configured with a common voltage range as a predetermined voltage range for obtaining the characteristics of the battery.

10. The degradation determination device for a secondary battery according to claim 8, characterized in that, The charge / discharge control unit is configured to allow the voltage of the secondary battery to deviate from a preset normal operating range when the battery pack is being charged or discharged.

11. The degradation determination device for a secondary battery according to claim 8, characterized in that, The charge / discharge control unit is configured to allow the voltage of the secondary battery to deviate from a preset usable range when the battery pack is being charged or discharged.

12. The degradation determination device for a secondary battery according to claim 8, characterized in that, The battery characteristic acquisition unit, the determination unit, and the charge / discharge control unit are located in the cloud. The battery pack is configured to connect to the cloud via a scanning tool with communication capabilities.

13. The degradation determination device for a secondary battery according to any one of claims 8 to 12, characterized in that, The battery pack is for use in a vehicle, and the charge / discharge control unit is configured to perform the charge / discharge while the battery pack is mounted in the vehicle.

14. The degradation determination device for a secondary battery according to claim 13, characterized in that, The charge / discharge control unit is configured to charge and discharge the secondary battery via a device mounted on the vehicle.

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