Secondary battery diagnosis system and secondary battery diagnosis method

Abstract

A secondary battery diagnosis system according to an embodiment of the present technology selects, on the basis of normal OCV data pertaining to a first secondary battery in a normal state, specific OCV data with which the regular OCV data can be approximated from among a plurality of virtual OCV data obtained from a plurality of positive electrode OCP data and a plurality of negative electrode OCP data. The secondary battery diagnosis system furthermore estimates, on the basis of the positive electrode OCP data and the negative electrode OCP data from which the specific OCV data is obtained, a plurality of deterioration OCP data for when the first secondary battery deteriorates under various conditions, and determines, on the basis of the plurality of deterioration OCP data obtained through the estimation, an OCV measurement section for measuring the OCV of a second secondary battery.

Description

Secondary battery diagnostic system and secondary battery diagnostic method

[0001] The present technology relates to a secondary battery diagnostic system and a secondary battery diagnostic method.

[0002] As the use of lithium-ion secondary batteries expands, the depletion of natural resources such as lithium and cobalt, which are the raw materials for these batteries, is becoming a problem. One way to solve this problem is to repeatedly reuse lithium-ion secondary batteries until the end of their product life. For efficient secondary use, it is important to properly understand the deterioration state of secondary batteries at the end of their primary use and to carry out secondary use appropriate to that state.

[0003] Methods for diagnosing the deterioration state of a secondary battery are disclosed in, for example, Patent Documents 1 to 3.

[0004] JP 2023-077830 A JP 2023-030370 A Japanese Patent No. 6918433 A

[0005] However, when the active material used in a secondary battery is unknown in advance, it is necessary to measure the open circuit potential (OCP) of the positive and negative electrodes of the secondary battery. However, since OCP measurement requires a significant amount of time, performing OCP measurement each time a deterioration diagnosis is performed on an individual secondary battery impairs usability. Therefore, it is desirable to provide a secondary battery diagnostic system and a secondary battery diagnostic method that enable deterioration diagnosis of a secondary battery without impairing usability, even when the active material used in the secondary battery is unknown in advance.

[0006] A secondary battery diagnostic system according to a first aspect of the present technology includes a memory unit and a processing unit. The memory unit stores normal OCV data for an OCV (Open Circuit Voltage) of a first secondary battery in a normal state, multiple positive electrode OCP (Open Circuit Potential) data for different positive electrode materials, and multiple negative electrode OCP data for different negative electrode materials. The processing unit includes an analysis unit, an estimation unit, a determination unit, an acquisition unit, and a diagnosis unit. The analysis unit compares multiple virtual OCV data obtained by combining any positive electrode OCP data from the multiple positive electrode OCP data read from the memory unit with any negative electrode OCP data from the multiple negative electrode OCP data read from the memory unit, with the normal OCV data, and selects specific OCV data from the multiple virtual OCV data that can approximate the normal OCV data. The estimation unit estimates multiple pieces of degradation OCV data when the first secondary battery deteriorates under various conditions, based on the positive electrode OCP data and negative electrode OCP data from which the specific OCV data selected by the analysis unit can be obtained. The determination unit determines an OCV measurement interval for measuring the OCV of a second secondary battery of the same type as the first secondary battery, based on the multiple pieces of degradation OCV data obtained by the estimation unit. The acquisition unit charges the second secondary battery by intermittently charging the second secondary battery during the OCV measurement interval obtained by the determination unit and continuously charging it during intervals other than the OCV measurement interval, thereby acquiring diagnosed OCV data for the second secondary battery. The diagnosis unit is capable of diagnosing deterioration of the second secondary battery based on the diagnosed OCV data obtained by the acquisition unit.

[0007] A secondary battery diagnosis method according to a second aspect of the present technology includes the following five steps: (1) comparing a plurality of virtual OCV data obtained by combining any positive electrode open circuit potential (OCP) data among a plurality of positive electrode OCP data each having different positive electrode materials with any negative electrode OCP data among a plurality of negative electrode OCP data each having different negative electrode materials with normal OCV data for the OCV (Open Circuit Voltage) of a first secondary battery in a normal state, and selecting, from the plurality of virtual OCV data, specific OCV data that can approximate the normal OCV data; (2) estimating, based on the positive electrode OCP data and negative electrode OCP data from which the selected specific OCV data is obtained, a plurality of degraded OCV data when the first secondary battery is degraded under various conditions; and (3) determining, based on the plurality of degraded OCV data obtained by the estimation unit, an OCV measurement section for measuring the OCV of a second secondary battery of the same type as the first secondary battery. (4) Charging the second secondary battery by intermittently charging the second secondary battery during the OCV measurement period and continuously charging the second secondary battery during periods other than the OCV measurement period, and acquiring diagnosed OCV data for the second secondary battery. (5) Diagnosing the deterioration of the second secondary battery based on the diagnosed OCV data.

[0008] In a secondary battery diagnostic system according to a first aspect of the present technology and a secondary battery diagnostic method according to a second aspect of the present technology, specific OCV data capable of approximating the normal OCV data is selected from a plurality of virtual OCV data obtained from a plurality of positive electrode OCP data and a plurality of negative electrode OCP data based on normal OCV data of a first secondary battery in a normal state. As a result, even if the active materials of the positive and negative electrodes of the first secondary battery in a normal state are unknown, OCP data of the positive and negative electrodes of the first secondary battery in a normal state (positive electrode OCP data and negative electrode OCP data from which the specific OCV data is obtained) can be obtained. In addition, in the present technology, a plurality of degradation OCV data when the first secondary battery deteriorates under various conditions is estimated based on the positive electrode OCP data and negative electrode OCP data from which the specific OCV data is obtained, and an OCV measurement section for measuring the OCV of a second secondary battery of the same type as the first secondary battery is determined based on the plurality of degradation OCV data obtained by estimation. In this technology, the second secondary battery is charged intermittently only during the OCV measurement interval, and continuous charging is performed during intervals other than the OCV measurement interval, thereby charging the second secondary battery and obtaining diagnosed OCV data for the second secondary battery. This allows the second secondary battery to be obtained without constantly performing intermittent charging during charging, thereby obtaining diagnosed OCV data in a short period of time. As described above, this technology makes it possible to perform deterioration diagnosis of a secondary battery without compromising usability, even when the active material used in the secondary battery is unknown in advance.

[0009] Note that the effects of the present technology are not necessarily limited to the effects described here, but may be any of a series of effects related to the present technology described below.

[0010] FIG. 1 is a diagram illustrating a schematic configuration example of a secondary battery diagnostic system according to a first embodiment of the present technology. FIG. 2 is a diagram illustrating an example of a measured voltage waveform obtained in a normal OCV measurement mode. FIG. 3 is a diagram illustrating an example of a measured voltage waveform obtained in a diagnosed OCV measurement mode. FIG. 4 is a diagram illustrating an example of an OCV curve of a secondary battery in a normal state obtained by measurement, and example OCP curves of a positive electrode and a negative electrode read from the storage unit of FIG. 1. FIG. 5 is a diagram illustrating an example of a plurality of deteriorated OCV curves when a secondary battery deteriorates under various conditions. FIG. 6 is a diagram illustrating an example of a similarity table stored in the storage unit of FIG. 1. FIG. 7 is a diagram illustrating an example of a plurality of dQ / dV-V curves obtained from the plurality of deteriorated OCV curves of FIG. 5. FIG. 8 is a diagram illustrating an example of a deterioration diagnosis procedure in the charge / discharge device of FIG. 1. FIG. 9 is a diagram illustrating a schematic configuration example of a secondary battery diagnostic system according to a second embodiment of the present technology. FIG. 10 is a diagram illustrating a schematic configuration example of the server device of FIG. 9. FIG. 11 is a diagram illustrating a schematic configuration example of a secondary battery diagnostic system according to a third embodiment of the present technology. FIG. 12 is a diagram showing an example of a schematic configuration of the diagnostic device shown in FIG.

[0011] Hereinafter, embodiments of the present technology will be described in detail with reference to the drawings. The description will be made in the following order: 1. First embodiment: An example in which a charge / discharge device performs a deterioration diagnosis of a secondary battery (FIGS. 1 to 8). 2. Second embodiment: An example in which a server device on a network performs a deterioration diagnosis of a secondary battery (FIGS. 9 and 10). 3. Third embodiment: An example in which a diagnostic device provided between a charge / discharge device and a secondary battery performs a deterioration diagnosis of a secondary battery (FIGS. 11 and 12).

[0012] 1. First Embodiment [Configuration] A configuration of a secondary battery diagnostic system according to a first embodiment of the present technology will be described. Fig. 1 illustrates a schematic configuration example of a secondary battery diagnostic system according to the first embodiment of the present technology. The secondary battery diagnostic system according to the present embodiment includes, for example, as shown in Fig. 1, a secondary battery pack 100 and a charging / discharging device 200 capable of charging / discharging the secondary battery pack 100. The charging / discharging device 200 is a stand-alone device that does not have a function of communicating with an external device.

[0013] 1, the secondary battery pack 100 includes a secondary battery 110. The charging / discharging device 200 not only has a function of charging / discharging the secondary battery 110, but also has a function of diagnosing the deterioration of the secondary battery 110.

[0014] The secondary battery 110 is a lithium-ion secondary battery. The lithium-ion secondary battery included in the secondary battery 110 may be a unit cell, a battery block in which a plurality of unit cells are connected, or an assembled battery in which a battery block and accessories are integrally packed. In an assembled battery, a plurality of lithium-ion secondary batteries are connected in series. The assembled battery may also include a plurality of lithium-ion secondary batteries electrically connected in parallel.

[0015] Next, the configuration of the charging / discharging device 200 will be described.

[0016] The charging / discharging device 200 includes, for example, a charging / discharging circuit 210, a charging / discharging control circuit 220, an IV measurement circuit 230, a processing unit 240, a storage unit 250, and a display unit 260, as shown in FIG.

[0017] The charge / discharge circuit 210 has a charge circuit that charges the secondary battery 110 and a discharge circuit that discharges the secondary battery 110. The charge circuit includes, for example, a generator and a converter. The charge / discharge control circuit 220 is capable of controlling the current for charging the secondary battery 110 and controlling the current for discharging the secondary battery 110. The charge / discharge control circuit 220 is configured, for example, by an MPU (Micro-Processing Unit) that performs charge / discharge control, or a CPU (Central Processing Unit) into which a charge / discharge control program is loaded.

[0018] The charge / discharge control circuit 220 is capable of performing charge control in accordance with a charge mode control signal input from the processing unit 240. For example, when a signal indicating a "regular OCV (Open Circuit Voltage) measurement mode" is input as a charge mode control signal from the processing unit 240, the charge / discharge control circuit 220 is capable of controlling the charge / discharge circuit 210 to discharge the secondary battery 110 to a predetermined voltage (first voltage) and then intermittently charge the secondary battery 110 to a predetermined voltage (second voltage higher than the first voltage). For example, when a signal indicating a "diagnosed OCV measurement mode" is input as a charge mode from the processing unit 240, the charge / discharge control circuit 220 is capable of controlling the charge / discharge circuit 210 to discharge the secondary battery 110 to a predetermined voltage (first voltage) and then charge the secondary battery 110 to the predetermined voltage (second voltage higher than the first voltage). Here, in the diagnosed OCV measurement mode, the charge / discharge control circuit 220 is capable of controlling the charge / discharge circuit 210 to perform intermittent charging in the OCV measurement section from the first voltage to the second voltage, and to perform continuous charging in sections other than the OCV measurement section.

[0019] The charge / discharge circuit 210 is capable of applying an intermittent current (multiple constant current pulses) to the secondary battery 110 to intermittently charge the secondary battery 110. The width of the constant current pulse in the intermittent current is, for example, 30 seconds, depending on data regarding the current pulse width included in the charge mode control signal. The period of the constant current pulse in the intermittent current is, for example, 1 minute, depending on data regarding the constant current pulse period included in the charge mode control signal. The charge / discharge circuit 210 is capable of setting the OCV measurement period based on, for example, intermittent period data 256 included in the charge mode control signal.

[0020] 2 shows an example of an intermittent charge waveform obtained by measuring the voltage of the secondary battery 110 with the IV measurement circuit 230 when an intermittent current is applied to the secondary battery 110 from the charge / discharge circuit 210 in the "normal OCV measurement mode." In the intermittent charge waveform shown in Fig. 2, when a constant current pulse is applied to the secondary battery 110, the measured voltage rises in response, and when the application of the constant current pulse to the secondary battery 110 is stopped, the measured voltage decreases in response, the rate of decrease in the measured voltage gradually slows down, and the measured voltage becomes a constant value.

[0021] 3 shows an example of a charging waveform obtained by measuring the voltage of the secondary battery 110 with the IV measurement circuit 230 when, in the "diagnosed OCV measurement mode," an intermittent current is applied from the charge / discharge circuit 210 to the secondary battery 110 during the OCV measurement interval and a continuous current is applied during intervals other than the OCV measurement interval (continuous charging interval). In the charging waveform shown in FIG. 3 , when a constant current is applied to the secondary battery 110 during intervals other than the OCV measurement interval, the measured voltage rises in response. Furthermore, in the charging waveform shown in FIG. 3 , when a constant current pulse is applied to the secondary battery 110 during the OCV measurement interval, the measured voltage rises in response. When the application of the constant current pulse to the secondary battery 110 is stopped, the measured voltage decreases in response. The rate of decrease in the measured voltage gradually slows down, and the measured voltage becomes a constant value.

[0022] 3, times ta to tb, tc to td, and te to tf correspond to the OCV measurement intervals, and the remaining intervals correspond to the continuous charging intervals. The time required to charge from the first voltage to the second voltage in the "diagnosed OCV measurement mode" (charging time Tb) is shorter than the time required to charge from the first voltage to the second voltage in the "regular OCV measurement mode" (charging time Ta). This is because the total period during which the application of constant current pulses is stopped is shorter in the "diagnosed OCV measurement mode" than in the "regular OCV measurement mode."

[0023] The IV measurement circuit 230 includes a measurement circuit that measures the current flowing through the secondary battery 110 and the voltage across the terminals of the secondary battery 110. Hereinafter, the current flowing through the secondary battery 110 will be referred to as the current of the secondary battery 110. Furthermore, the voltage across the terminals of the secondary battery 110 will be referred to as the voltage of the secondary battery 110. The IV measurement circuit 230 is capable of measuring the current and voltage of the secondary battery 110 while the secondary battery 110 is being discharged (while the secondary battery 110 is being discharged to a first voltage) and while the secondary battery 110 is being charged (while the secondary battery 110 is being charged from the first voltage to a second voltage). The IV measurement circuit 230 is capable of outputting the current value and the voltage value obtained by measurement in the measurement circuit to the processing unit 240.

[0024] The processing unit 240 is configured by, for example, at least one CPU or a circuit including at least one semiconductor integrated circuit. As shown in FIG. 1 , the processing unit 240 includes, for example, a charge mode setting unit 241, an OCV acquisition unit 242, an OCP (Open Circuit Potential) analysis unit 243, a deteriorated OCV estimation unit 244, an intermittent interval determination unit 245, and a deterioration diagnosis unit 246.

[0025] The storage unit 250 is configured, for example, with a nonvolatile memory such as a flash memory. The storage unit 250 stores, for example, a positive electrode OCP-DB 251 and a negative electrode OCP-DB 252. The positive electrode OCP-DB 251 includes multiple pieces of positive electrode OCP data for different positive electrode materials. The negative electrode OCP-DB 252 includes multiple pieces of negative electrode OCP data for different negative electrode materials. The storage unit 250 stores data obtained by processing in the processing unit 240 (for example, normal OCV data 253, a similarity table 254, virtual OCV data 255, intermittent interval data 256, deteriorated OCV data 257, measured OCV data 258, and deterioration diagnosis data 259). The intermittent interval data 256 includes, for example, data regarding the OCV measurement interval described below.

[0026] The charge mode setting unit 241 is capable of outputting a signal indicating the "regular OCV measurement mode" or the "diagnosed OCV measurement mode" as a charge mode control signal to the charge / discharge control circuit 220. The charge mode setting unit 241 is capable of outputting, for example, a flag indicating the "regular OCV measurement mode" and data regarding the current pulse width and the current pulse period as a charge mode control signal to the charge / discharge control circuit 220. The charge mode setting unit 241 is capable of outputting, for example, a flag indicating the "diagnosed OCV measurement mode", data regarding the current pulse width and the current pulse period, and intermittent section data 256 read out from the storage unit 250 as a charge mode control signal to the charge / discharge control circuit 220.

[0027] In the "normal OCV measurement mode," the OCV acquisition unit 242 is capable of acquiring normal OCV data 253 (see FIG. 4 ) about the OCV of the secondary battery 110 (first secondary battery) in a normal state based on the voltage value measured by the IV measurement circuit 230. Hereinafter, the secondary battery 110 in a normal state will be referred to as the secondary battery 110a. The "normal state" refers to a state in which the deterioration state of the electrodes, etc. of the secondary battery 110 is within the expected design value range (i.e., a normal state). In the "diagnosed OCV measurement mode," the OCV acquisition unit 242 is capable of acquiring data about the OCV of a secondary battery 110 (second secondary battery) of the same type as the secondary battery 110a (measured OCV data 258) based on the voltage value measured by the IV measurement circuit 230. The term "same type" refers to a secondary battery formed with the same structure and materials as the secondary battery 100a. Hereinafter, the secondary battery 110 of the same type as the secondary battery 110a will be referred to as secondary battery 110b.

[0028] Among the plurality of positive electrode OCP data included in the positive electrode OCP-DB 251 of the storage unit 250, any one of the positive electrode OCP data is designated as positive electrode OCP data 251-i (see FIG. 4). Furthermore, among the plurality of negative electrode OCP data included in the negative electrode OCP-DB 252 of the storage unit 250, any one of the negative electrode OCP data is designated as negative electrode OCP data 252-j (see FIG. 4). At this time, the OCP analysis unit 243 is capable of generating a plurality of virtual OCV data 255 (see FIG. 5) from a combination of any one of the positive electrode OCP data 251-i and any one of the negative electrode OCP data 252-j. The OCP analysis unit 243 is capable of storing the generated plurality of virtual OCV data 255 in the storage unit 250. The "virtual OCV data 255" indicates that it is not obtained by measuring an actual secondary battery, but is OCV data of a virtual secondary battery composed of a positive electrode having the characteristics described by the positive electrode OCP data 251-i and a negative electrode having the characteristics described by the negative electrode OCP data 252-j.

[0029] The OCP analysis unit 243 is capable of comparing the generated plurality of virtual OCV data 255 with the normal OCV data 253, and selecting, from the plurality of virtual OCV data 255, specific OCV data that can approximate the normal OCV data 253. For example, the OCP analysis unit 243 is capable of selecting, from the positive electrode OCP-DB 251 and the negative electrode OCP-DB 252, a combination of positive electrode OCP data 251-i and negative electrode OCP data 252-j that can approximate the normal OCV data 253.

[0030] The OCP analysis unit 243 may be capable of searching for a combination of positive electrode OCP data 251-i and negative electrode OCP data 252-j that can best reproduce the normal OCV data 253, for example, by using the following formula (1). In formula (1), i is the serial number of the plurality of positive electrode OCP data included in the positive electrode OCP-DB 251, and j is the serial number of the plurality of negative electrode OCP data included in the negative electrode OCP-DB 252. α is set so that Residual in formula (1) is minimized. ｐ , β ｐ , α ｎ , βｎ is optimized. For example, when the residual calculated for certain i and j is smaller than the minimum value of the residuals calculated in the past, the OCP analysis unit 243 may be able to set the residual calculated for certain i and j as the minimum value of the residual. For example, the OCP analysis unit 243 may be able to store the residuals obtained for each combination of i and j as similarities, associate them with each combination of i and j, and store them in the storage unit 250 as a similarity table 254 (see FIG. 6 ).

[0031]

[0032] The OCP analysis unit 243 may be capable of searching for a combination of positive electrode OCP data groups and negative electrode OCP data groups that can best reproduce the normal OCV data 253, for example, using the following formula (2). In formula (2), one group (positive electrode OCP data group) is made up of multiple positive electrode OCP data, and one group (negative electrode OCP data group) is made up of multiple negative electrode OCP data. i is the serial number of the multiple positive electrode OCP data groups included in the positive electrode OCP-DB 251, and j is the serial number of the multiple negative electrode OCP data groups included in the negative electrode OCP-DB 252. α is calculated so that Residual in formula (2) is minimized. ｐ , β ｐ , α ｎ , β ｎ The OCP analysis unit 243 may be configured to set the residual calculated at certain times i and j as the minimum residual value when the residual calculated at certain times i and j is smaller than the minimum residual value calculated in the past, for example.

[0033]

[0034] The OCP analysis unit 243 may be capable of weighting average the plurality of positive electrode OCP data in each positive electrode OCP data group, and weighting average the plurality of negative electrode OCP data in each negative electrode OCP data group, for example, using the following formula (3): In formula (3), w is a weighting coefficient, and k is a serial number of the plurality of OCP data in the group. The OCP analysis unit 243 may be capable of weighting average the plurality of positive electrode OCP data in each negative electrode OCP data group, for example, using the following formula (3): ｐ , β ｐ , α ｎ , β ｎ It may be possible to use the above formula as it is, and when the Residual calculated at a certain time i, j is smaller than the minimum value of the Residual calculated in the past, set the Residual calculated at a certain time i, j as the minimum value of the Residual.

[0035]

[0036] The degradation OCV estimation unit 244 is capable of estimating multiple degradation OCV data 257 when the secondary battery 110a in a normal state degrades under various conditions, based on the positive electrode OCP data 251-i and the negative electrode OCP data 251-j that can best reproduce the normal OCV data 253.

[0037] The intermittent interval determination unit 245 is capable of determining an OCV measurement interval for measuring the OCV of the secondary battery 110b based on the plurality of pieces of deteriorated OCV data 257 obtained by the deteriorated OCV estimation unit 244. The intermittent interval determination unit 245 is capable of deriving, for example, from each piece of deteriorated OCV data 257, a dQ / dV-V data group (see FIG. 7 ) that indicates the relationship between the terminal voltage of the secondary battery 110b and the value obtained by dividing the charge capacity of the secondary battery 110b by the terminal voltage of the secondary battery 110b.

[0038] In FIG. 7 , La, Lb, and Lc are line segments connecting the minimum value points of the curved valley regions in the plurality of degraded OCV data 257. FIG. 7 illustrates three voltage sections (Va-Vb, Vc-Vd, and Ve-Vf) as voltage sections including the curved valley regions. The term "curved" refers to the fact that the line segments La, Lb, and Lc are curved rather than linear. In the above-described three voltage sections (Va-Vb, Vc-Vd, and Ve-Vf), the sensitivity to voltage varies more widely than in other voltage sections in the plurality of degraded OCV data 257. In other words, the above-described three voltage sections (Va-Vb, Vc-Vd, and Ve-Vf) are voltage sections in which the OCV shape changes sharply depending on the degraded state of the battery.

[0039] For example, the intermittent interval determination unit 245 can determine, as the OCV measurement interval, a voltage interval corresponding to a curved valley region included in the derived dQ / dV-V data group. For example, the intermittent interval determination unit 245 can store the OCV measurement interval derived in this manner in intermittent interval data 256 in the storage unit 250. For example, the intermittent interval data 256 stores data on three voltage intervals (Va to Vb, Vc to Vd, and Ve to Vf) as data on the OCV measurement interval.

[0040] The degradation diagnosis unit 246 is capable of diagnosing degradation of the secondary battery 110b based on diagnosed OCV data 258 of the secondary battery 110b acquired by the OCV acquisition unit 242. The display unit 260 is capable of displaying the results of the degradation diagnosis by the degradation diagnosis unit 246.

[0041] Next, a description will be given of the deterioration diagnosis of the secondary battery 110 in the secondary battery diagnostic system according to this embodiment.

[0042] FIG. 8 shows an example of a procedure for diagnosing deterioration of the secondary battery 110 in the charging / discharging device 200. First, a user connects the secondary battery pack 100 including the secondary battery 110a in a normal state to the charging / discharging device 200. Next, the user instructs the charging / discharging device 200 to perform a normal OCV measurement. The processing unit 240 then outputs a signal indicating the normal OCV measurement mode to the charging / discharging control circuit 220 as a charge mode control signal. The charging / discharging control circuit 220 controls the charging / discharging circuit 210 in accordance with the signal indicating the normal OCV measurement mode input from the processing unit 240. As a result, the charging / discharging circuit 210 first discharges the secondary battery 110a in a normal state to a predetermined voltage (first voltage) (step S101). Next, the charging / discharging circuit 210 intermittently charges the secondary battery 110a from the predetermined voltage (first voltage) to a predetermined voltage (second voltage) (step S102).

[0043] In step S102, the IV measurement circuit 230 measures the current and voltage of the secondary battery 110a and outputs the measurement values ​​(current value and voltage value) obtained thereby to the processing unit 240. The processing unit 240 generates normal OCV data 253 based on the measurement values ​​obtained from the IV measurement circuit 230 and stores the data in the storage unit 250 (step S102).

[0044] Next, the processing unit 240 reproduces the normal OCV data 253 using the positive electrode OCP-DB 251 and the negative electrode OCP-DB 252 (step S103). The processing unit 240 generates a plurality of virtual OCV data 255, for example, from a combination of any positive electrode OCP data 251-i read from the positive electrode OCP-DB 251 and any negative electrode OCP data 252-j read from the negative electrode OCP-DB 252. The processing unit 240 compares the generated plurality of virtual OCV data 255 with the normal OCV data 253, for example, and selects specific OCV data from the plurality of virtual OCV data 255 that can approximate the normal OCV data 253. For example, the processing unit 240 selects, from among the plurality of virtual OCV data 255, the virtual OCV data 255 that can approximate the normal OCV data 253 as the specific OCV data.

[0045] Next, the processing unit 240 estimates a plurality of pieces of degraded OCV data 257 obtained when the secondary battery 110a in a normal state is degraded under various conditions, based on the positive electrode OCP data 251-i and the negative electrode OCP data 251-j that can best reproduce the normal OCV data 253 (step S104). Subsequently, the processing unit 240 determines an OCV measurement section for measuring the OCV of the secondary battery 110b, based on the plurality of pieces of degraded OCV data 257 obtained by the degraded OCV estimation unit 244 (step S105). For example, the processing unit 240 derives a group of dQ / dV-V data from each piece of degraded OCV data 257, which indicates the relationship between the terminal voltage of the secondary battery 110b and the value obtained by dividing the charge capacity of the secondary battery 110b by the terminal voltage of the secondary battery 110b. The processing unit 240 determines, for example, a voltage section corresponding to a curved valley region included in the derived dQ / dV-V data group as the OCV measurement section.

[0046] Next, the user connects the secondary battery pack 100 including the secondary battery 110a to the charge / discharge device 200. Subsequently, the user instructs the charge / discharge device 200 to perform a diagnosed OCV measurement. The processing unit 240 then outputs a signal indicating a diagnosed OCV measurement mode to the charge / discharge control circuit 220 as a charge mode control signal. The charge / discharge control circuit 220 controls the charge / discharge circuit 210 in accordance with the signal indicating the diagnosed OCV measurement mode input from the processing unit 240. As a result, the charge / discharge circuit 210 first discharges the secondary battery 110b to a predetermined voltage (first voltage) (step S106). Subsequently, the charge / discharge circuit 210 intermittently charges the secondary battery 110b from the predetermined voltage (first voltage) to a predetermined voltage (second voltage) (step S107).

[0047] In step S107, the IV measurement circuit 230 measures the current and voltage of the secondary battery 110b and outputs the obtained measurement values ​​(current value and voltage value) to the processing unit 240. The processing unit 240 generates OCV data (diagnosed OCV data 258) of the secondary battery 110b based on the measurement values ​​obtained from the IV measurement circuit 230 and stores the data in the storage unit 250 (step S107). Thereafter, the processing unit 240 performs a deterioration diagnosis of the secondary battery 110b based on the diagnosed OCV data 258 and causes the display unit 260 to display the result (deterioration diagnosis data 259). In this manner, a deterioration diagnosis of the secondary battery 110 in the charging / discharging device 200 is performed.

[0048] [Effects] Next, the effects of the secondary battery diagnostic system according to this embodiment will be described.

[0049] In the present embodiment, based on normal OCV data 253 of secondary battery 110a in a normal state, specific OCV data that can approximate normal OCV data 253 is selected from a plurality of virtual OCV data 255 obtained from a plurality of positive electrode OCP data and a plurality of negative electrode OCP data stored in memory unit 250. In this way, even if the active materials of the positive and negative electrodes of secondary battery 110a in a normal state are unknown, OCP data of the positive and negative electrodes of secondary battery 110a in a normal state (positive electrode OCP data and negative electrode OCP data from which the specific OCV data can be obtained) can be obtained.

[0050] Furthermore, in this embodiment, multiple pieces of degradation OCV data 257 are estimated based on the positive electrode OCP data and negative electrode OCP data from which specific OCV data is obtained when secondary battery 110a in a normal state deteriorates under various conditions, and an OCV measurement period for measuring the OCV of secondary battery 110b is determined based on the multiple pieces of degradation OCV data 257 obtained by estimation. In this embodiment, intermittent charging is further performed only during the OCV measurement period, and diagnosed OCV data 258 for secondary battery 110b is obtained based on the intermittent charging voltage between the terminals of secondary battery 110b obtained during the OCV measurement period. This allows the diagnosed OCV data 258 for secondary battery 110b to be obtained without constantly performing intermittent charging during charging, thereby enabling the diagnosed OCV data 258 to be obtained in a short time. As described above, in this embodiment, degradation diagnosis of a secondary battery can be performed without impairing usability, even when the active material used in the secondary battery is not known in advance.

[0051] In this embodiment, the virtual OCV data 255 that can approximate the normal OCV data 253 is selected as the specific OCV data from among the plurality of virtual OCV data 255. As a result, even if the active materials of the positive and negative electrodes of the secondary battery 110a in the normal state are unknown, the OCP data of the positive and negative electrodes of the secondary battery 110a in the normal state (positive electrode OCP data and negative electrode OCP data from which the specific OCV data can be obtained) can be obtained.

[0052] In this embodiment, a set of dQ / dV-V data is derived from each piece of deteriorated OCV data 257, indicating the relationship between the terminal voltage of the secondary battery 110b and the value obtained by dividing the charge capacity of the secondary battery 110b by the terminal voltage of the secondary battery 110b. Furthermore, a voltage section corresponding to a curved valley region included in the derived dQ / dV-V data set is the OCV measurement section. This allows intermittent charging to be performed only during the OCV measurement section, and diagnostic OCV data 258 for the secondary battery 110b can be obtained based on the terminal voltage of the secondary battery 110b obtained during the OCV measurement section. As a result, the diagnostic OCV data 258 for the secondary battery 110b can be obtained without constantly performing intermittent charging during charging, thereby enabling the diagnostic OCV data 258 to be obtained in a short time.

[0053] In this embodiment, the charge / discharge circuit 210 and the charge / discharge control circuit 220 are provided in the charge / discharge device 200. This allows the charge / discharge device 200 alone to obtain the diagnosed OCV data 258.

[0054] 2. Second Embodiment Next, a configuration of a secondary battery diagnostic system according to a second embodiment of the present technology will be described. Fig. 9 illustrates a schematic configuration example of a secondary battery diagnostic system according to the second embodiment of the present technology. The secondary battery diagnostic system according to the present embodiment includes, for example, a secondary battery pack 100, a charging / discharging device 300 capable of charging / discharging the secondary battery pack 100, and a server device 400, as shown in Fig. 9 . The charging / discharging device 300 and the server device 400 are capable of communicating with each other via a network 500. The network 500 is configured to include, for example, the Internet, a cloud network, or a network specific to a business operator.

[0055] 9 , the charging / discharging device 300 includes a charging / discharging circuit 210, a charging / discharging control circuit 220, an IV measurement circuit 230, a processing unit 310, a communication unit 320, and a display unit 260. The processing unit 310 is configured, for example, by at least one CPU or a circuit including at least one semiconductor integrated circuit. The processing unit 310 is capable of transmitting time-series data of measurement values ​​obtained from the IV measurement circuit 230 to the server device 400 via the communication unit 320. The communication unit 320 is a communication interface capable of communicating with the server device 400 via the network 500.

[0056] 10 shows an example of a schematic configuration of server device 400. For example, as shown in FIG. 10 , server device 400 includes processing unit 240, storage unit 250, and communication unit 410. Communication unit 410 is a communication interface capable of communicating with charging / discharging device 300 via network 500. Processing unit 240 is capable of diagnosing deterioration of secondary battery 110b based on time-series data of measurement values ​​acquired via communication unit 410 and positive electrode OCP-DB 251 and negative electrode OCP-DB 252 in storage unit 250.

[0057] In this embodiment, the deterioration diagnosis of secondary battery 110b is performed by server device 400. This makes it possible to keep the calculation processing capacity of charging / discharging device 300 low, and to use a general-purpose device as charging / discharging device 300. As a result, the cost of charging / discharging device 300 can be kept low.

[0058] 3. Third Embodiment Next, a configuration of a secondary battery diagnostic system according to a third embodiment of the present technology will be described. Fig. 11 illustrates a schematic configuration example of a secondary battery diagnostic system according to the third embodiment of the present technology. The secondary battery diagnostic system according to the present embodiment includes, for example, a secondary battery pack 100, a charge / discharge device 600 capable of charging / discharging the secondary battery pack 100, and a diagnostic device 700, as shown in Fig. 11 .

[0059] 11 , the charging / discharging device 600 includes a charging / discharging circuit 210 and a charging / discharging control circuit 220. The charging / discharging circuit 210 is capable of applying a continuous current to the secondary battery 110. The charging / discharging control circuit 220 is capable of controlling charging of the charging / discharging circuit 210 so that a continuous current is output from the charging / discharging circuit 210.

[0060] 12 , the diagnostic device 700 includes a switching circuit 710, an IV measurement circuit 230, a processing unit 240, a storage unit 250, and a display unit 260. The switching circuit 710 is a circuit that can switch the electrical connection between the charge / discharge circuit 210 and the secondary battery 110 on and off.

[0061] The processing unit 240 includes, for example, a connection / disconnection control unit 247, a charging mode setting unit 241, an OCV acquisition unit 242, an OCP analysis unit 243, a deteriorated OCV estimation unit 244, an intermittent interval determination unit 245, and a deterioration diagnosis unit 246, as shown in FIG. 12 .

[0062] The charge mode setting unit 241 is capable of outputting a signal indicating the "regular OCV measurement mode" or the "diagnosed OCV measurement mode" as a charge mode control signal to the on-off control unit 247. The charge mode setting unit 241 is capable of outputting, for example, a flag indicating the "regular OCV measurement mode" and data regarding the current pulse width and the current pulse period as a charge mode control signal to the on-off control unit 247. The charge mode setting unit 241 is capable of outputting, for example, a flag indicating the "diagnosed OCV measurement mode", data regarding the current pulse width and the current pulse period, and intermittent section data 256 read out from the storage unit 250 as a charge mode control signal to the on-off control unit 247.

[0063] The on / off control unit 247 outputs a control signal to the on / off circuit 710 when the charge / discharge circuit 210 is continuously charging the secondary battery 110, and can cause the on / off circuit 710 to make and break the electrical connection between the charge / discharge circuit 210 and the secondary battery 110. This enables the charge / discharge circuit 210 to intermittently charge the secondary battery 110 by the on / off circuit 710 making and breaking the electrical connection between the charge / discharge circuit 210 and the secondary battery 110.

[0064] The on-off control unit 247 is capable of performing on-off control in accordance with a charge mode control signal input from the charge mode setting unit 241. For example, when a signal indicating a "regular OCV measurement mode" is input as a charge mode control signal from the charge mode setting unit 241, the on-off control unit 247 is capable of controlling the on-off circuit 710 so that the secondary battery 110 is discharged to a predetermined voltage (first voltage) and then intermittently charged to a predetermined voltage (second voltage higher than the first voltage). For example, when a signal indicating a "diagnosed OCV measurement mode" is input as a charge mode from the charge mode setting unit 241, the on-off control unit 247 is capable of controlling the on-off circuit 710 so that the secondary battery 110 is discharged to the predetermined voltage (first voltage) and then intermittently charged to the predetermined voltage (second voltage higher than the first voltage) in the OCV measurement section and continuously charged in sections other than the OCV measurement section.

[0065] In this embodiment, a switching circuit 710 is provided between the charge / discharge circuit 210 and the secondary battery 110, and further, a switching control unit 247 is provided to control the switching of the switching circuit 710. This allows the use of an inexpensive device that can only output continuous current as the charge / discharge device 600.

[0066] The present technology may also be configured as follows: <1> A storage unit that stores normal OCV data regarding the OCV (Open Circuit Voltage) of a first secondary battery in a normal state, a plurality of positive electrode OCP (Open Circuit Potential) data each having different positive electrode materials, and a plurality of negative electrode OCP data each having different negative electrode materials, and a processing unit that performs processing based on the normal OCV data, the plurality of positive electrode OCP data, and the plurality of negative electrode OCP data read from the storage unit, wherein the processing unit is an analysis unit that compares the normal OCV data with a plurality of virtual OCV data obtained by combining any one of the positive electrode OCP data among the plurality of positive electrode OCP data read from the storage unit and any one of the negative electrode OCP data among the plurality of negative electrode OCP data read from the storage unit, and selects, from the plurality of virtual OCV data, specific OCV data that can approximate the normal OCV data; a determination unit that determines an OCV measurement interval for measuring the OCV of a second secondary battery of the same type as the first secondary battery, based on the plurality of degradation OCV data obtained by the estimation unit; an acquisition unit that charges the second secondary battery by intermittently charging the second secondary battery during the OCV measurement interval obtained by the determination unit and continuously charging the second secondary battery during intervals other than the OCV measurement interval, thereby acquiring diagnosed OCV data for the second secondary battery; and a diagnosis unit that performs a degradation diagnosis of the second secondary battery based on the diagnosed OCV data obtained by the acquisition unit. <2> The secondary battery diagnostic system according to <1>, wherein the determination unit derives a dQ / dV-V data group from each of the degradation OCV data, and determines a voltage section corresponding to a curved valley region included in the derived dQ / dV-V data group as the OCV measurement section.<3> The secondary battery diagnostic system according to <1> or <2>, further comprising: a charging circuit that charges the second secondary battery by performing the intermittent charging and the continuous charging in a section other than the OCV measurement section, and a measurement circuit that measures the inter-terminal voltage of the second secondary battery in the OCV measurement section. <4> The secondary battery diagnostic system according to <1> or <2>, further comprising: a communication unit capable of communicating with a charging device that includes: a charging circuit that charges the second secondary battery by performing the intermittent charging and the continuous charging in a section other than the OCV measurement section, and a measurement circuit that measures the inter-terminal voltage of the second secondary battery in the OCV measurement section, <5> The secondary battery diagnostic system according to <1> or <2>, further comprising: a measurement circuit that measures a terminal voltage of the second secondary battery in the OCV measurement section; a charging circuit that charges the second secondary battery by performing the intermittent charging on the second secondary battery and performing the continuous charging in sections other than the OCV measurement section; and a switching circuit that switches on and off an electrical connection with the second secondary battery.<6> Comparing a plurality of virtual OCV data obtained by combining any one of a plurality of positive electrode OCP (Open Circuit Potential) data for different positive electrode materials with any one of a plurality of negative electrode OCP data for different negative electrode materials, with normal OCV data for the OCV (Open Circuit Voltage) of a first secondary battery in a normal state, and selecting specific OCV data that can approximate the normal OCV data from the plurality of virtual OCV data; estimating a plurality of degradation OCV data when the first secondary battery is degraded under various conditions based on the positive electrode OCP data and the negative electrode OCP data from which the selected specific OCV data is obtained; and determining an OCV measurement interval for measuring the OCV of a second secondary battery of the same type as the first secondary battery, based on the plurality of degradation OCV data obtained by the estimation unit; a secondary battery diagnosis method comprising: charging the second secondary battery by intermittently charging the second secondary battery during the OCV measurement period and continuously charging the second secondary battery during a period other than the OCV measurement period, and acquiring diagnosed OCV data for the second secondary battery; and diagnosing deterioration of the second secondary battery based on the diagnosed OCV data.

Claims

1. A storage unit that stores normal OCV data for an OCV (Open Circuit Voltage) of a first secondary battery in a normal state, a plurality of positive electrode OCP (Open Circuit Potential) data for different positive electrode materials, and a plurality of negative electrode OCP data for different negative electrode materials; and a processing unit that performs processing based on the normal OCV data, the plurality of positive electrode OCP data, and the plurality of negative electrode OCP data read from the storage unit, wherein the processing unit comprises: an analysis unit that compares the normal OCV data with a plurality of virtual OCV data obtained by combining any one of the plurality of positive electrode OCP data read from the storage unit with any one of the plurality of negative electrode OCP data read from the storage unit, and selects, from the plurality of virtual OCV data, specific OCV data that can approximate the normal OCV data; a determination unit that determines an OCV measurement section for measuring an OCV of a second secondary battery of the same type as the first secondary battery, based on the plurality of deteriorated OCV data obtained by the estimation unit; an acquisition unit that acquires diagnosed OCV data for the second secondary battery by intermittently charging the second secondary battery in the OCV measurement section obtained by the determination unit and continuously charging the second secondary battery in a section other than the OCV measurement section, thereby charging the second secondary battery; and a diagnosis unit that performs a deterioration diagnosis of the second secondary battery, based on the diagnosed OCV data obtained by the acquisition unit.

2. The secondary battery diagnostic system according to claim 1, wherein the determination unit derives a dQ / dV-V data group from each of the deteriorated OCV data, and determines a voltage section corresponding to a curved valley region included in the derived dQ / dV-V data group as the OCV measurement section.

3. A secondary battery diagnostic system as described in claim 1 or claim 2, further comprising: a charging circuit that charges the second secondary battery by performing the intermittent charging and the continuous charging in a section other than the OCV measurement section; and a measurement circuit that measures the terminal voltage of the second secondary battery in the OCV measurement section.

4. A secondary battery diagnostic system as described in claim 1 or claim 2, further comprising a communication unit capable of communicating with a charging device including a charging circuit that charges the second secondary battery by performing the intermittent charging and the continuous charging in a section other than the OCV measurement section, and a measurement circuit that measures the terminal voltage of the second secondary battery in the OCV measurement section, wherein the acquisition unit acquires the diagnosed OCV data based on the terminal voltage of the second secondary battery obtained via the communication unit.

5. A secondary battery diagnostic system as described in claim 1 or claim 2, further comprising: a measurement circuit that measures the terminal voltage of the second secondary battery in the OCV measurement section; a charging circuit that charges the second secondary battery by performing the intermittent charging on the second secondary battery and performing the continuous charging in a section other than the OCV measurement section; and a switching circuit that switches on and off the electrical connection with the second secondary battery.

6. comparing a plurality of virtual OCV data obtained by combining any one of a plurality of positive electrode OCP (Open Circuit Potential) data for different positive electrode materials with any one of a plurality of negative electrode OCP data for different negative electrode materials with normal OCV data for the OCV (Open Circuit Voltage) of a first secondary battery in a normal state, and selecting specific OCV data that can approximate the normal OCV data from the plurality of virtual OCV data; estimating a plurality of degradation OCV data when the first secondary battery is degraded under various conditions based on the positive electrode OCP data and the negative electrode OCP data from which the selected specific OCV data is obtained; and determining an OCV measurement section for measuring the OCV of a second secondary battery of the same type as the first secondary battery based on the plurality of degradation OCV data obtained by the estimation unit; a second secondary battery diagnosis method comprising: charging the second secondary battery by intermittently charging the second secondary battery during the OCV measurement section and continuously charging the second secondary battery during a section other than the OCV measurement section, and acquiring diagnosed OCV data for the second secondary battery; and diagnosing deterioration of the second secondary battery based on the diagnosed OCV data.

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