Secondary battery state determination device and secondary battery diagnostic method

Abstract

To provide a secondary battery state determination device capable of determining the internal state of a secondary battery from one measurement of the secondary battery.SOLUTION: A secondary battery state determination device comprises: a database in which relaxation spectra measured for a plurality of secondary batteries and active material names of positive and negative electrodes used in electrodes of the secondary batteries are recorded; a measurement unit which measures time-series data of a secondary battery to be diagnosed; a calculation unit which calculates a relaxation spectrum of the secondary battery to be diagnosed from the time-series data measured by the measurement unit; a comparison unit which acquires, from the database, the relaxation spectrum of the secondary battery matching the active material name used in the secondary battery to be diagnosed and compares the acquired relaxation spectrum with the relaxation spectrum calculated by the calculation unit; and a determination unit which determines, on the basis of a comparison result of the comparison unit, whether or not an abnormality has occurred in the secondary battery to be diagnosed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a configuration of a secondary battery state determination device and a secondary battery diagnosis method using the same, and particularly relates to a technique effective for evaluating the residual value of a secondary battery.

Background Art

[0002] Lithium-ion secondary batteries (hereinafter referred to as secondary batteries) are expected to be applied to various product groups from electric mobility applications such as electric vehicles to stationary power supplies, and are being used, and their demand is steadily expanding. Generally, it is known that the life of a secondary battery is closely related to its usage conditions, and if the secondary battery continues to be used under high-load conditions, the battery performance will rapidly deteriorate (hereinafter referred to as abnormal deterioration). Therefore, in order to stably use the secondary battery until the product life, it is important to appropriately determine the deterioration state of the secondary battery.

[0003] In recent years, attempts have also been made to reuse used batteries that have reached the end of their life in electric vehicles as stationary power supplies. From the viewpoints of product reliability and safety, a method for determining the deterioration state and the presence or absence of abnormal deterioration of used batteries at the time of reuse has been demanded.

[0004] Examples of battery abnormalities include current concentration and lithium precipitation. The former current concentration is deterioration that occurs when the secondary battery is used at a large current, and is a phenomenon in which a large current flows locally inside the battery, causing that part to rapidly deteriorate. The latter lithium precipitation is a deterioration phenomenon that occurs when the secondary battery is used at a low temperature and a high voltage, and is a phenomenon in which lithium ions precipitate on the negative electrode during the charge and discharge process, deteriorating the capacity and resistance of the secondary battery. Furthermore, it has also been reported that if the lithium precipitation phenomenon continues to progress, an internal short circuit of the secondary battery may eventually occur.

[0005] Therefore, in order to detect battery abnormalities inside the battery, studies have been conducted to analyze the state inside the battery. For example, in the summary of Patent Document 1, it is described that "an analysis device is provided with a battery state analysis unit that detects a change in the state of a battery component based on a change in the peak of the relaxation time in a predetermined frequency band."

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In order to implement the method of Patent Document 1, it is necessary to compare the peak change of the relaxation time in a predetermined frequency band before (when not deteriorated) and after (when deteriorated) the capacity and resistance of the secondary battery deteriorate. Therefore, in the method of Patent Document 1, at least two measurements are required, namely when not deteriorated and when deteriorated.

[0008] Generally, since measuring the battery state requires a certain measurement time and man-hours, it is preferable that the number of measurements is smaller. Also, in the method of Patent Document 1, measurement of the secondary battery at the non-deteriorated time is essential, so it cannot be applied to uses other than those that continue to be used from the non-deteriorated time to the deteriorated time. For example, in the case of a used battery, since the characteristics of the secondary battery when not deteriorated cannot be obtained even if the used battery is measured, the method of Patent Document 1 cannot be applied.

[0009] Therefore, an object of the present invention is to provide a state determination device for a secondary battery and a diagnosis method for a secondary battery that can determine the state inside the battery from a single measurement of the secondary battery.

Means for Solving the Problems

[0010] In order to solve the above problems, the present invention includes a relaxation spectrum measured for a plurality of secondary batteries, a database recording the names of the positive and negative electrode active materials used in the electrodes of those secondary batteries, a measurement unit that measures time-series data of a secondary battery to be diagnosed, a calculation unit that calculates the relaxation spectrum of the secondary battery to be diagnosed from the time-series data measured by the measurement unit, a comparison unit that acquires from the database the relaxation spectrum of a secondary battery that matches the name of the active material used in the secondary battery to be diagnosed and compares it with the relaxation spectrum calculated by the calculation unit, and a determination unit that determines whether an abnormality has occurred in the secondary battery to be diagnosed based on the comparison result in the comparison unit.

[0011] Further, the present invention is a method for diagnosing a secondary battery, comprising: (a) a step of measuring time-series data of a secondary battery to be diagnosed; (b) a step of calculating the relaxation spectrum of the secondary battery to be diagnosed from the time-series data measured in step (a); (c) a step of acquiring from a database the relaxation spectrum of a secondary battery that matches the name of the active material used in the secondary battery to be diagnosed; (d) a step of comparing the relaxation spectrum acquired in step (c) with the relaxation spectrum calculated in step (b); and (e) a step of determining whether an abnormality has occurred in the secondary battery to be diagnosed based on the comparison result in step (d).

Effects of the Invention

[0012] According to the present invention, it is possible to realize a state determination device for a secondary battery and a method for diagnosing a secondary battery that can determine the state inside the battery from a single measurement of the secondary battery.

[0013] This enables an appropriate evaluation of the residual value of the secondary battery.

[0014] Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Figure 5

Figure 6A

Figure 6B

Figure 7

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same reference numerals are given to configurations having the same configuration or similar functions, and detailed descriptions of overlapping parts will be omitted.

[0017] Also, hereinafter, the spectrum in a two-axis coordinate system with one axis being the relaxation time and the other axis being the spectrum intensity will be referred to as the relaxation spectrum or the relaxation time distribution.

Examples

[0018] With reference to FIGS. 1 to 4 and FIG. 7, the state determination device for a secondary battery and the diagnostic method for a secondary battery according to Example 1 of the present invention will be described.

[0019] FIG. 1 is a block diagram showing a state determination device 100 for a secondary battery according to this embodiment. As shown in FIG. 1, the state determination device 100 for a secondary battery according to this embodiment uses measurement data for the battery system 200 or the secondary battery 210.

[0020] Here, the battery system 200 is a system composed of at least one or more secondary batteries 210 and its control device (not shown). Hereinafter, embodiments will be described with the case where the state determination device 100 is connected to the secondary battery 210 as an example. However, the method of the present invention is not limited to the following embodiments and can be arbitrarily modified within a range that does not significantly impair the effects of the present invention.

[0021] The state determination device 100 for a secondary battery mainly includes an input unit 10, a measurement unit 11, a calculation unit 12, a recording unit 13, a comparison unit 14, a determination unit 15, and an output unit 16. All of these may be integrally configured, or at least a part thereof may be separately configured.

[0022] The input unit 10 inputs the material names of the active materials used for the positive and negative electrodes of the secondary battery 210. The "active material" is one of the materials constituting the electrode of the secondary battery. The active material plays a role in advancing the charge and discharge reaction of the secondary battery by storing and releasing lithium ions during charge and discharge. Representative active materials include graphite, lithium manganate, Li(NiMnCo)O2, etc. As the input method to the input unit 10, there is no particular limitation as long as it is an input method capable of specifying the active material used in the secondary battery 210.

[0023] For example, the substance name, composition formula, etc. may be input, or an abbreviation generally used as a proper noun (for example, "NMC" in the case of Li(NiMnCo)O2) may be input, or a data series used in machine learning such as a descriptor may also be used.

[0024] The measurement unit 11 measures time-series data of each value including at least one of a DC current value and at least one of a DC voltage value or the SOC (State Of Charge) of the secondary battery 210 during charging or discharging of the secondary battery 210. That is, the time-series data includes time-series data of the DC current value and time-series data of at least one of the DC voltage value or the SOC of the secondary battery 210. The measurement is performed constantly or at a predetermined time interval (for example, every 1 minute, etc.) during use including during charging and discharging of the secondary battery 210, during standby without performing charging and discharging, etc.

[0025] Since there is a correlation between the DC voltage value and the SOC, hereinafter, as an example, the measurement unit 11 measures time-series data regarding the DC voltage value. However, the measurement unit 11 may measure time-series data of the SOC. Also, in this embodiment, the time-series data may further include time-series data of the temperature of the secondary battery 210.

[0026] The measurement unit 11 extracts time-series data at a period (timing) capable of calculating a relaxation spectrum from the aggregate of the measured time-series data (so-called "raw data"). The relaxation spectrum is a continuous function of the relaxation time and is a relaxation spectrum (relaxation time distribution) in a two-axis coordinate system with one axis (for example, the horizontal axis) being the relaxation time and the other axis (for example, the vertical axis) being the spectrum intensity. For calculating the relaxation spectrum, it is preferable to use, for example, each time-series data in at least any one of the periods during constant voltage charging, after charging, or after discharging. After charging, it may be after constant voltage charging or after constant current charging. After discharging, it may be after constant voltage discharging or after constant current discharging.

[0027] When extracting time-series data during constant-voltage charging, the measurement unit 11 extracts the time-series data of the voltage value, current value, and temperature of the secondary battery 210 from the time t1 when the constant-voltage charging starts to the time t2 when the constant-voltage charging ends. "Constant-voltage charging" is a charging method in which the secondary battery 210 is charged while being held at a constant voltage value. Further, the measurement unit 11 also extracts the voltage value of the secondary battery 210 before (preferably immediately before) the start of charging. There is no limitation on the time from time t1 to time t2, but preferably it is 1 minute or more and 120 minutes or less, more preferably 10 minutes or more and 60 minutes or less.

[0028] When extracting time-series data after charging (after the end of charging) or after discharging (after the end of discharging), the measurement unit 11 extracts the time-series data of the voltage value, current value, and temperature of the secondary battery 210 from the end time t3 of charging or discharging to a predetermined time t4. Further, the measurement unit 11 also acquires the current value immediately before the end of charging or discharging of the secondary battery 210. There is no limitation on the time from time t3 to time t4, but preferably it is 1 minute or more and 120 minutes or less, more preferably 10 minutes or more and 60 minutes or less.

[0029] The calculation unit 12 calculates a relaxation spectrum from the time-series data in at least any one of the periods during constant-voltage charging, after charging, or after discharging. By using these time-series data, the relaxation spectrum can be calculated. The specific calculation method is as follows, but the calculation method is not limited to the following examples.

[0030] <Calculation Method 1: When calculating the relaxation spectrum from the measurement data during constant-voltage charging> In this case, the relaxation spectrum ρ(τ) can be calculated from Equation (1) using the measurement data.

[0031] ρ(τ)=L -1 (I(t) / ΔV)···Equation (1) ρ(τ) represents the relaxation spectrum, ΔV represents the difference between the battery voltage value before the start of charging (preferably immediately before) and the voltage value during constant-voltage charging, and I(t) represents the time-series data of the current value during constant-voltage charging. Also, the symbol L -1 represents the inverse Laplace transform of I(t) / ΔV.

[0032] <Calculation method 2: When calculating the relaxation spectrum from the measurement data after charging or after discharging> In this case, the relaxation spectrum ρ(τ) can be calculated from Equation (2) using the measurement data.

[0033] ρ(τ)=L -1 (V(t) / I0) ··· Equation (2) ρ(τ) represents the relaxation spectrum, I0 represents the current value immediately before the end of charging or immediately before the end of discharging, and V(t) represents the time-series data of the voltage value after charging or after discharging. Also, the symbol L -1 ( represents the inverse Laplace transform of V(t) / I0.

[0034] In the recording unit 13, the relaxation spectrum measured for the secondary battery 210 in which no battery abnormality has occurred and the name of the active material used in the secondary battery 210 are recorded in association with each other. Note that the secondary battery 210 for recording data in the recording unit 13 may be a secondary battery different from the secondary battery 210 included in the battery system 200.

[0035] Here, "battery abnormality" indicates a degradation event such as current concentration or lithium precipitation. Also, "a secondary battery in which no battery abnormality has occurred" indicates, for example, a secondary battery in a state (non-degraded state) where battery performance such as the capacity and resistance of the secondary battery is equal to or better than the performance values specified in the product specification. Further, "recorded in association with each other" means that the relaxation spectrum of the secondary battery 210 recorded in the recording unit 13 can be acquired based on the name of the active material used in the secondary battery 210.

[0036] It is preferable that the recording unit 13 records the relaxation spectrum measured for a plurality of secondary batteries 210 and the active material names. In the plurality of secondary batteries 210, it is preferable that at least one of the active materials used for the positive electrode and the negative electrode is different. For example, it is preferable that the relaxation spectra of secondary batteries using graphite and lithium manganate for the negative electrode and the positive electrode, respectively, or secondary batteries using graphite and Li(NiMnCo)O2 (hereinafter referred to as "NMC") for the negative electrode and the positive electrode, respectively, are recorded. Further, it is particularly preferable that the recording unit 13 records the relaxation spectrum of a secondary battery (half cell) using lithium metal for either the positive electrode or the negative electrode.

[0037] In the comparison unit 14, the shape information of the relaxation spectra of the calculation unit 12 and the recording unit 13 is compared to determine the presence or absence of battery abnormalities. The following shows the comparison procedure of the relaxation spectra of the calculation unit 12 and the recording unit 13.

[0038] In the comparison unit 14, based on the active material name of the secondary battery 210 acquired from the input unit 10, secondary battery data using the same active material is searched from the recording unit 13, and the relaxation spectrum measured for the secondary battery is acquired. Here, when data that completely matches the active material name of the secondary battery 210 does not exist on the recording unit 13, the following processing is performed.

[0039] (1) When data that matches the combination of the positive electrode and the negative electrode of the secondary battery 210 does not exist In this case, the relaxation spectra of the half cell that matches the active material name of the positive electrode of the secondary battery 210 and the half cell that matches the active material name of the negative electrode are acquired from the recording unit 13. For example, when the secondary battery 210 is composed of graphite and lithium manganate, the relaxation spectra of the half cells for graphite and lithium manganate, respectively, are acquired from the recording unit 13.

[0040] (2) When the positive electrode, the negative electrode, or both of the secondary battery 210 are composed of a plurality of active materials and data corresponding to the combination does not exist In this case, the recording unit 13 acquires the relaxation spectra of the half-cells corresponding to each active material. For example, when the negative electrode of the secondary battery 210 is graphite and the positive electrode is composed of lithium manganate and NMC, the recording unit 13 acquires the relaxation spectra of the half-cells for graphite, lithium manganate, and NMC.

[0041] (3) When the element mixing ratios of the active materials used in the secondary battery 210 are different In this case, the recording unit 13 acquires the relaxation spectra of the secondary batteries with different element mixing ratios. For example, when the active material of the positive electrode of the secondary battery 210 is NMC and the element mixing ratio of N (nickel), M (manganese), and C (cobalt) is 8:1:1, the recording unit 13 may acquire the relaxation spectrum with an element mixing ratio of 1:1:1 and substitute it for the relaxation spectrum with an element mixing ratio of 8:1:1.

[0042] Subsequently, the comparison unit 14 compares the shape information of the relaxation spectrum A acquired from the recording unit 13 with the relaxation spectrum B of the secondary battery 210 obtained by the calculation unit 12. As the shape information, for example, it is preferable to compare the number of peaks in the relaxation spectrum, the intensity of each peak, the position of each peak, the area of each peak, the full width at half maximum of each peak, the skewness of each peak, and further the intensity ratio and area ratio of these. As a specific example, it is effective to normalize the relaxation spectra A and B and the relaxation time using the following formula (3) and compare the difference in the shapes of the two on the graph.

[0043] J(τ*) = ρ(τ*) / ∫dτ*ρ(τ*) ··· Formula (3) However, τ* = τ / τ_peak.

[0044] Here, ∫dτ* represents the integral with respect to the relaxation time τ*, and τ* means that the relaxation time τ is normalized by the position τ_peak of the peak having the maximum area in the relaxation spectrum.

[0045] Fig. 2 schematically shows an example of the peak position (τ_peak) of the relaxation spectrum. Figs. 3A and 3B show the application and comparison of the above formula (3) to the relaxation spectra A and B. Fig. 3A shows the state before the application of formula (3), and Fig. 3B shows the state after the application of formula (3).

[0046] When a plurality of relaxation spectra of half-cells are obtained from the recording unit 13, these plurality of relaxation spectra are summed up to obtain a relaxation spectrum A. As a method for summing up the relaxation spectra of each half-cell, for example, a method of multiplying the relaxation spectrum and the relaxation time by a constant multiple and then summing them up using the following formula (4) is effective. As an example, an example of the summing method when the relaxation spectra for the half-cells of the positive electrode and the negative electrode are obtained from the recording unit 13 is shown.

[0047] ρ(τ)=a1×ρ_positive(a2×τ)+b1×ρ_negative(b2×τ) ··· Formula (4) Here, a1, a2, b1, and b2 are constants, and ρ_positive(τ) and ρ_negative(τ) represent the relaxation spectra for the half-cells of the positive electrode and the negative electrode, respectively.

[0048] The ρ(τ) in the above formula (4) is compared with the relaxation spectrum B obtained by the calculation unit 12 as the relaxation spectrum A. At this time, for various constants in formula (4), they are determined so that X defined by the following formula (5) becomes the minimum.

[0049] X = ∫dτ|ρ(τ)-ρ’(τ)| ··· Formula (5) Here, ρ’ represents the relaxation spectrum B, and the symbol |A| means taking the absolute value of A. In the comparison unit 14, after determining each constant in the relaxation spectrum A by the above procedure, the shape information of the relaxation spectra A and B is compared.

[0050] Based on the comparison result of the relaxation spectra in the comparison unit 14, the determination unit 15 determines whether a battery abnormality has occurred in the secondary battery 210. The following shows the method for determining a battery abnormality.

[0051] Since the number of peaks in the relaxation spectrum corresponds to the number of reaction processes inside the battery, an increase in the number of peaks suggests that unsteady reactions are occurring inside the battery. Therefore, if the number of peaks in relaxation spectrum B is greater than that in relaxation spectrum A, it is determined that a battery abnormality has occurred.

[0052] Even if the number of peaks in the relaxation spectrum increases, if the peak positions are close to each other, it becomes difficult to accurately determine the number of peaks. However, since changes appear in the peak intensity, area, full width at half maximum, etc., when the difference in the peak intensity, area, full width at half maximum between relaxation spectra A and B exceeds a predetermined threshold value, it can be determined that a battery abnormality has occurred.

[0053] Through the above procedure, the state determination device 100 can determine the presence or absence of a battery abnormality from a single measurement of the secondary battery 210. Therefore, it is not necessary to measure the secondary battery when it is not deteriorated as in Patent Document 1, and the state can be determined even for a battery whose battery characteristics have already deteriorated, such as a used battery.

[0054] Fig. 7 shows a typical diagnostic method for a secondary battery using the state determination device 100 of this embodiment.

[0055] When the state determination device 100 starts processing, first, in step S1, the measurement unit 11 measures the time-series data of the secondary battery to be diagnosed.

[0056] Next, in step S2, the calculation unit 12 calculates the relaxation spectrum of the secondary battery to be diagnosed from the time-series data measured in step S1.

[0057] Next, in step S3, the comparison unit 14 acquires from the recording unit 13 (database) the relaxation spectrum of a secondary battery that matches the name of the active material used in the secondary battery to be diagnosed.

[0058] Subsequently, in step S4, the comparison unit 14 compares the relaxation spectrum acquired from the recording unit 13 (database) with the relaxation spectrum calculated in step S2.

[0059] Next, in step S5, the determination unit 15 determines whether or not an abnormality has occurred in the secondary battery to be diagnosed based on the comparison result in step S4.

[0060] Finally, in step S6, the determination result in step S5 is output to the output unit 16 (display unit), notified to the user, and the process ends.

[0061] The secondary battery 210 to which the present invention is applicable includes any form such as, for example, a secondary battery cell, a secondary battery module, a secondary battery pack, and a secondary battery system. Further, the secondary battery 210 may be mounted on, for example, electric mobility such as a ship, an aircraft, a vehicle (a battery electric train, an electric vehicle), may be mounted on a stationary battery system, or the use may be changed during use. For example, the present invention can also be applied when the secondary battery 210 used in electric mobility is reused as a stationary battery system.

[0062] A deteriorated secondary battery 210 was prepared, and it was verified whether the presence or absence of a battery abnormality could be determined from one measurement by the state determination device 100. At the time of verification, the relaxation spectra of secondary batteries using graphite for the negative electrode and lithium manganate for the positive electrode, and the relaxation spectra of secondary batteries using graphite for the negative electrode and NMC for the positive electrode were recorded in the recording unit 13, respectively. Since the capacities of these secondary batteries were 50 Ah and 7 Ah, respectively, and were also about the same as the rated capacity described in the product specification, the relaxation spectra recorded in the recording unit 13 correspond to the relaxation spectra when not deteriorated.

[0063] As Example 1, an 18650-type secondary battery (battery capacity 2 Ah) using graphite and NMC for the negative electrode and the positive electrode, respectively, was prepared. This secondary battery is different from the two secondary batteries recorded in the recording unit 13. Specifically, the external shapes of the secondary batteries recorded in the recording unit 13 are all rectangular, whereas the secondary battery used in Example 1 is cylindrical. Also, the battery capacity of the former is 7 Ah to 50 Ah, whereas the latter is about 2 Ah.

[0064] The above-described 18650-type secondary battery 210 was left standing in an environment of 0°C, and the full charge and full discharge were repeated 100 times at a current value of 2 A, thereby deteriorating the secondary battery capacity by about 20%. The deteriorated secondary battery 210 was connected to the state determination device 100, and the material information of the positive electrode and the negative electrode was input to the input unit 10, respectively. Further, the secondary battery 210 was subjected to constant current charging from 3.8 V to 3.9 V at a current value of 4 A, and when the voltage reached 3.9 V, the charging was switched to constant voltage charging. Thereafter, the constant voltage charging was continued for about 1 hour, and the time-series data of the voltage value and the current value during charging were acquired by the measurement unit 11.

[0065] In the comparison unit 14, the comparison result between the relaxation spectrum B of the secondary battery 210 obtained by the calculation unit 12 and the relaxation spectrum A acquired from the recording unit 13 is shown in FIG. 4. In the comparison, the peak intensity and the relaxation time of the relaxation spectra A and B were normalized using Equation (3). From FIG. 4, it can be confirmed that the number of peaks of the relaxation spectrum B is larger than that of the relaxation spectrum A.

[0066] Based on the above results, the determination unit 15 determined that a battery abnormality had occurred in the secondary battery 210, and output the determination result to the output unit 16.

[0067] For verification of the above determination result, the secondary battery 210 was disassembled and analyzed to investigate the presence or absence of a battery abnormality. As a result, the occurrence of lithium precipitation was confirmed at the negative electrode of the secondary battery 210, and it was confirmed that the determination result was correct.

Example

[0068] With reference to FIG. 5, a state determination device for a secondary battery and a diagnostic method for a secondary battery according to Example 2 of the present invention will be described.

[0069] As Example 2, the secondary battery 210 of Example 1 was left standing in a 25°C environment and charged and discharged 1000 times repeatedly. Other test conditions and measurement conditions were the same as those in Example 1.

[0070] The comparison results of the relaxation spectra A and B in the comparison unit 14 in Example 2 are shown in FIG. 5. From FIG. 5, the relaxation spectra A and B are in good agreement, and the determination unit 15 determines that no battery abnormality has occurred and outputs the determination result to the output unit 16.

[0071] For verification of the above determination result, the secondary battery 210 was disassembled and analyzed to investigate the presence or absence of battery abnormalities. As a result, no traces such as lithium precipitation or current concentration were confirmed in the secondary battery 210, and it was confirmed that the determination result was correct.

Example

[0072] With reference to FIGS. 6A and 6B, a secondary battery state determination device and a secondary battery diagnosis method according to Example 3 of the present invention will be described.

[0073] As Example 3, the relaxation spectrum recorded in the recording unit 13 was changed to data measured with another secondary battery. As another secondary battery, a pouch-type secondary battery with a battery capacity of 34 mAh was prepared. Also, the positive and negative electrode materials were lithium manganate and graphite, and NMC and graphite, respectively. Using the data of this recording unit 13, the presence or absence of battery abnormalities was determined under the same conditions as in Example 1 and Example 2.

[0074] The comparison results of the relaxation spectra A and B in the comparison unit 14 in Example 3 are shown in FIGS. 6A and 6B. In this example, both the case of having a battery abnormality and the case of having no battery abnormality were confirmed.

[0075] In the case of having a battery abnormality, as shown in FIG. 6A, it can be confirmed that the number of peaks of the relaxation spectrum B is larger than that of the relaxation spectrum A. Based on this result, the determination unit 15 determines that a battery abnormality has occurred in the secondary battery 210 and outputs the determination result to the output unit 16.

[0076] On the other hand, in the case of having no battery abnormality, as shown in FIG. 6B, the relaxation spectra A and B are in good agreement, and the determination unit 15 determines that no battery abnormality has occurred and outputs the determination result to the output unit 16.

[0077] The comparison results of FIGS. 6A and 6B are in good agreement with the comparison results of Example 1 (FIG. 4) and Example 2 (FIG. 5), and it was confirmed that the presence or absence of battery abnormalities can be correctly determined even in the case of Example 3.

[0078] Note that the present invention is not limited to the above-described embodiments, and various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, or replace other configurations for a part of the configuration of each embodiment.

Explanation of Reference Numerals

[0079] 10... Input unit 11... Measurement unit 12... Calculation unit 13... Recording unit 14... Comparison unit 15... Determination unit 16... Output unit 100... State determination device (for secondary battery) 200... Battery system 210... Secondary battery.

Claims

1. A database that records relaxation spectra measured for a plurality of secondary batteries and the active material names of the positive and negative electrodes used in the electrodes of those secondary batteries, A measurement unit that measures time-series data of a secondary battery to be diagnosed, A calculation unit that calculates a relaxation spectrum of the secondary battery to be diagnosed from the time-series data measured by the measurement unit, A comparison unit that acquires from the database a relaxation spectrum of a secondary battery that matches the active material name used in the secondary battery to be diagnosed and compares it with the relaxation spectrum calculated by the calculation unit, A determination unit that determines whether or not an abnormality has occurred in the secondary battery to be diagnosed based on the comparison result in the comparison unit, A state determination device for a secondary battery, characterized by comprising:

2. The state determination device for a secondary battery according to Claim 1, wherein the relaxation spectrum is a relaxation time distribution in a two-axis coordinate system with one axis being the relaxation time and the other axis being the spectrum intensity. A state determination device for a secondary battery.

3. The state determination device for a secondary battery according to Claim 1, wherein the comparison unit compares the shape information of the relaxation spectrum, and the shape information includes at least one of the number of peaks, the intensity of the peaks, the position of the peaks, the area of the peaks, the full width at half maximum of the peaks, and the skewness of the peaks in the relaxation spectrum. A state determination device for a secondary battery.

4. The state determination device for a secondary battery according to Claim 3, wherein the comparison unit normalizes and compares the area and relaxation time of the relaxation spectrum when comparing the shape information. A state determination device for a secondary battery.

5. The state determination device for a secondary battery according to Claim 1, wherein the secondary battery to be diagnosed is a secondary battery that has deteriorated due to being used in an electric mobility application including an electric vehicle and a battery electric vehicle. A state determination device for a secondary battery.

6. The state determination device for a secondary battery according to Claim 1, wherein the secondary battery to be diagnosed is a secondary battery that has deteriorated due to being used as a stationary power source. A state determination device for a secondary battery.

7. The state determination device for a secondary battery according to Claim 1, wherein the database records a relaxation spectrum of a secondary battery in which lithium metal is used in at least one of the positive and negative electrodes. A state determination device for a secondary battery.

8. A state determination device for a secondary battery according to claim 1, wherein the measurement unit measures time-series data of each value including at least one of a DC current value during charge and discharge of the secondary battery to be diagnosed, a DC voltage value, or an SOC (state of charge). A state determination device for a secondary battery is characterized by this.

9. A state determination device for a secondary battery according to claim 1, wherein the calculation unit calculates a relaxation spectrum of the secondary battery to be diagnosed from time-series data in at least one of the periods during constant voltage charging, after charging, and after discharging of the secondary battery to be diagnosed. A state determination device for a secondary battery is characterized by this.

10. A method for diagnosing a secondary battery, comprising: (a) measuring time-series data of the secondary battery to be diagnosed; (b) calculating a relaxation spectrum of the secondary battery to be diagnosed from the time-series data measured in step (a); (c) obtaining from a database a relaxation spectrum of a secondary battery that matches the name of the active material used in the secondary battery to be diagnosed; (d) comparing the relaxation spectrum obtained in step (c) with the relaxation spectrum calculated in step (b); (e) determining whether an abnormality has occurred in the secondary battery to be diagnosed based on the comparison result in step (d). A method for diagnosing a secondary battery is characterized by having these steps.

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