Battery diagnostic device and battery diagnostic method

Abstract

The purpose of the present invention is to provide technology that is capable of determining a state of a battery quickly and in detail. This battery diagnosis device determines whether or not a battery is in a first state, on the basis of a first difference of battery voltage within 4 msec from the time point of completion of charging or discharging of the battery, and determines whether or not the battery is in a second state, on the basis of a second difference of the battery voltage thereafter.

Description

[Technical Field]

[0001] The present invention relates to a technique for diagnosing the state of a battery. [Background technology]

[0002] Patent Document 1 describes a technology for determining the degradation state of a storage battery. The document aims to "accurately determine the degradation state." It describes a technology in which "the terminal voltage of a secondary battery measured at the end or stop of charging or at the end or stop of discharging is designated as a first voltage value, the terminal voltage of the secondary battery measured a predetermined time after the first voltage value is measured as a second voltage value, the difference between the first voltage value and the second voltage value is calculated as a change ΔV, and this change ΔV is compared with a predetermined reference change to determine the degradation state" (see Abstract). The document further describes that if the ohmic loss resistance R1 is greater than a reference battery resistance within 0.01 seconds after the end of charging or discharging, the battery is determined to be degraded (see Figures 9, 0058-0059, 0063, and 0070). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-054413 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the battery resistance R is calculated using the amount of voltage change after charging and discharging, and the battery resistance R is compared with a reference battery resistance value to determine whether the battery has deteriorated. Meanwhile, in actual storage battery evaluation sites, it is necessary to determine whether the battery should be replaced or continued use. Therefore, it is necessary to determine the state of the storage battery in detail. For example, it is possible to determine detailed states such as (a) a fault state, or (b) a state in which the SoH (State of Health) has rapidly decreased. While conventional technologies such as Patent Document 1 can determine whether a battery has deteriorated, it is difficult to determine the detailed state of the battery. Furthermore, there is a demand for rapid diagnosis of the battery state.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide a technique that can quickly and precisely determine the state of a battery. [Means for solving the problem]

[0006] The battery diagnostic device of the present invention determines whether the battery is in a first state based on a first difference in battery voltage within 4 msec from the end point of charging or discharging of the battery, and further determines whether the battery is in a second state based on a second difference in battery voltage thereafter. [Effects of the Invention]

[0007] The battery diagnostic device according to the present invention can quickly and precisely determine the state of a battery. Other objects, configurations, advantages, etc. of the present invention will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram of a battery diagnostic device 100 according to a first embodiment. [Figure 2] 10 is an example of a screen of UI130. [Figure 3] 10 is a flowchart showing a procedure for the calculation unit 120 to diagnose the battery 200. [Figure 4]FIG. 10 is a diagram showing the change over time in the current and voltage output by the battery 200 after discharge. [Figure 5] 10 is an example of the phase frequency characteristic obtained in S301. [Figure 6] The voltage change over time from the first measurement point is Fourier transformed to determine the amplitude frequency characteristics, and the Cole-Cole plot is created using the amplitude. [Figure 7] FIG. 10 is a diagram showing the change in battery voltage over time during a rest period after charging. [Figure 8] 10 is a flowchart illustrating a procedure for diagnosing a battery 200 by a battery diagnostic device 100 according to a second embodiment. [Figure 9] This indicates that in the frequency range below f3, the phase in the phase frequency characteristics varies significantly from the reference value. [Figure 10] 10 is a flowchart illustrating a procedure for diagnosing a battery 200 by a battery diagnostic device 100 according to a third embodiment. [Figure 11] Examples of combinations of positive and negative electrode materials are shown below. [Figure 12] Examples of temperature ranges are shown below. [Figure 13] This is an example of the amplitude frequency characteristics used in S702 and S704. [Figure 14] 10 is a flowchart illustrating a procedure for determining a temperature range in S705. [Figure 15] 1 shows another example of the configuration of the battery diagnostic device 100. DETAILED DESCRIPTION OF THE INVENTION

[0009] <First Embodiment> 1 is a block diagram of a battery diagnostic device 100 according to a first embodiment of the present invention. The battery diagnostic device 100 includes a detection unit 110, a calculation unit 120, and a UI (User Interface) 130. When diagnosing the battery 200, the battery diagnostic device 100 is connected to the battery 200 and can charge or discharge the battery 200 or instruct a charge / discharge device to start or stop charging / discharging. The battery 200 may be a storage battery module or pack composed of multiple batteries.

[0010] The detection unit 110 acquires the detected voltage value V, the detected current value I, and the time t output by the battery 200. The calculation unit 120 diagnoses the state of the battery 200 using the detected values ​​acquired by the detection unit 110. The diagnostic procedure will be described later. The UI 130 can input the battery type, which is information necessary for diagnosis, give instructions to start diagnosis, and output the diagnosis results.

[0011] 2 is an example of a screen of the UI 130. Through the UI 130, an operator can input instructions to the battery diagnostic device 100, check the diagnosis results by the battery diagnostic device 100 at the diagnosis site, and so on.

[0012] 3 is a flowchart showing the procedure by which the calculation unit 120 diagnoses the battery 200. The calculation unit 120 starts this flowchart at an appropriate timing, such as when an instruction is received from the UI 130, when the SoC (State Of Charge) of the battery 200 reaches a predetermined value, or at predetermined intervals. The calculation unit 120 determines the state of the battery 200 as Rank A, Rank B, or Rank C according to this flowchart. The definitions of these Ranks will be described later.

[0013] (Figure 3: Step S301) The calculation unit 120 performs a Fourier transform on the change in battery voltage after the battery current is cut off, based on the voltage V, current I, and time t, which are input values ​​from the detection unit 110. Furthermore, using the results, it calculates dV0 / dt0, dV1 / dt1, and dV2 / dt2, which will be described later.

[0014] (Figure 3: Step S302) If dV0 / dt0 (first time rate of change of the first difference) is higher than a predetermined reference value, calculation unit 120 determines that the state of battery 200 is Rank C (first state). If the state is not determined to be Rank C, the process proceeds to step S303.

[0015] (Figure 3: Step S303) The calculation unit 120 acquires multiple measurements of the voltage V and calculates dV2 / dt2 (the second time rate of change of the second difference) for each measurement. If either of the following conditions is met, the calculation unit 120 determines the battery state as Rank B (second state): (a) dV2 / dt2 varies by more than a reference value between multiple measurements, or (b) the voltage change per unit time measured after charging and after discharging is greater than the voltage change after discharging (in normal products, the voltage change after charging is smaller than the voltage change after discharging due to the effect of hysteresis). If the battery state is not determined to be Rank B, the calculation unit 120 determines the battery state as Rank A.

[0016] (Individual battery state definitions) Define RankA, RankB, and RankC as follows: Rank A: Normal usable condition Rank B: Deterioration is accelerating and a rapid drop in SoH is observed, or the state immediately before this Rank C: Abnormal voltage or resistance is present, making charging or discharging impossible, or the state immediately preceding this.

[0017] When measuring the resistance of a Rank C battery, it can be observed that the internal resistance, negative electrode resistance, positive electrode resistance, and diffusion resistance are all high. In some cases, a sudden increase in voltage is observed during steady state operation after current is interrupted. This is used in S302 to diagnose whether the battery is Rank C or not.

[0018] When measuring the resistance of a Rank B battery, the main findings are an increase in internal resistance, an increase in positive electrode resistance, and variations in the resistance across multiple measurements. The positive electrode resistance of a Rank B battery depends on the charge capacity, and variations in the positive electrode resistance become more pronounced when the charge capacity is low. This is used in S303 to determine whether the battery is Rank B.

[0019] It is recommended that batteries 200 determined to be Rank B or Rank C be replaced or reused after considering safety. The calculation unit 120 may output a message to that effect on the UI 130. These ranks can be caused by a variety of factors, including physical damage, foreign matter contamination, metallic Li deposition, and accumulation of by-products.

[0020] (Definition of battery group) Furthermore, the calculation unit 120 can statistically process the incidence of each rank and the measurement results of SoH for a plurality of batteries, thereby making it possible to evaluate the performance of a battery group and predict the incidence of each rank.

[0021] The relationship between the rank occurrence rate for the Rank C group and the Rank B group and the cumulative usage time of the battery can be described as statistical data. This data has, for example, a region where the occurrence rate decreases over time, a region where it remains constant regardless of time, and a region where it increases over time. By referencing this curve using the cumulative usage time of the battery, it is possible to determine the occurrence rate of each rank and whether it is possible to continue using the battery. Alternatively, by defining the relationship between the occurrence rate in each region and the cumulative usage time using a Weibull distribution or the like, it is possible to determine whether each battery group can be continued to be used and to predict the occurrence rate of each rank. For example, if the m value of the Weibull distribution is equal to or greater than a threshold, it can be determined that the battery is not suitable for continued use. The statistical data can be created in advance and stored in the battery diagnostic device 100.

[0022] When measuring the SoH of a battery group determined to be a Rank B group, it can be assumed that the relationship between the SoH and the number of batteries with that SoH in the same battery group under the same usage conditions follows a normal distribution. The quality of the battery group can be quantified from the standard deviation of this distribution and the SoH, making it possible to compare the reliability of different battery groups. For example, as the cumulative usage time increases, various individual batteries, such as those with advanced degradation and those with no advanced degradation, emerge, and the variance of the distribution increases. Conversely, the variance is small when the cumulative usage time is short. Therefore, the standard deviation can be used to quantify the quality of the battery group. Alternatively, a process capability index or a similar value can be used as a quality index for the battery group. Other appropriate statistical indices may also be used.

[0023] Fig. 4 is a diagram showing the change over time in the current and voltage output by battery 200 after discharge. Calculation unit 120 performs a Fourier transform on the amount of voltage change over time from the first measurement point after current interruption to determine the phase frequency characteristic and amplitude frequency characteristic. Calculation unit 120 can identify t1, t2, and t3 in Figs. 4 and 5 using the phase frequency characteristic thus determined (Fig. 5).

[0024] t1 is the start point for measuring dV1 / dt1. t2 is the end point for measuring dV2 / dt2. t0 is the start time of the quiet period (however, depending on the sampling frequency, it may not be possible to obtain the value exactly at the start time of the quiet period, so for example, the sampling point immediately afterwards may be used). dV0 / dt0 can be measured starting from t0 and ending before t1. The end time of dV1 / dt1 is between t1 and t2. The start time of dV2 / dt2 may be the same as the end time of dV1 / dt1, or it may be later. t3 will be described later. The time regions from dt0 to dt2 may partially overlap, or there may be intervals between the regions.

[0025] Figure 5 shows an example of the phase frequency characteristics found in S301. In Figure 5, the frequency ranges from f1 to f2 are where the influence of the negative electrode reaction is prominent, from f2 to f3 are where the influence of the positive electrode reaction is prominent, and below f3 are where the influence of the diffusion reaction is prominent.

[0026] For example, t1 can be determined from the time when the amount of phase change approaches 0 on the high frequency side in the phase-frequency characteristics of Fig. 5. More simply, t1 can be determined as the first inflection point (the inflection point that first appears in a rest period) when the time axis is displayed logarithmically in the relationship between the amount of voltage change and time shown in Fig. 4. The range from f1 to f2 is the interval corresponding to the time constant of the negative electrode of the equivalent circuit of battery 200 (the interval including both sides of the reciprocal of the time constant).

[0027] For example, t2 can be determined from the value corresponding to the time constant of the positive electrode of the equivalent circuit of battery 200 in the phase-frequency characteristics of Fig. 5. More simply, the second inflection point (the second inflection point that appears in the rest period) when the time axis is displayed logarithmically in the relationship between the voltage change amount and time shown in Fig. 4 can be determined as t2. In other words, dt2 falls within the section defined by the two inflection points on the logarithmic time axis.

[0028] For example, t3 can be found from the frequency at which the amount of change in phase with respect to frequency approaches 0 on the low frequency side in the phase frequency characteristics of FIG.

[0029] (Calculation procedure for dV0 / dt0, dV1 / dt1, dV2 / dt2) dV0 / dt0 is the voltage change per unit time from the first measurement point (t0) after current interruption until dt0 has elapsed in FIG. 4 . In this method, the measurement start time (t1) of dV1 / dt1 is often set around 4 msec after current interruption, so the time length of dt0 is set to 4 msec or less. However, because the influence of voltage abnormalities and resistance abnormalities is particularly noticeable within 2 msec, and the sampling period in this method must be ½ or less of the 4 msec measurement start time (t1) of dV1 / dt1, dt0 is preferably set to 2 msec or less. The inventors have found that the dV0 / dt0 calculated as described above is highly correlated with the occurrence of abnormal voltage or resistance in the storage battery. This finding is utilized in the determination of step S302.

[0030] FIG. 6 shows a Cole-Cole plot created using the amplitude of the amplitude-frequency characteristics obtained by Fourier transforming the voltage change over time from the first measurement point. dV1 / dt1 corresponds to the voltage change per unit time in range (1) in FIG. 6. This range is where the influence of internal resistance is most pronounced. dV1 / dt1 is calculated as the voltage change per unit time when dt1 is set to within 4 msec from t1, for example. Note that range (1) should be set to an appropriate interval taking into account the measurement sampling period and resolution. The inventors have found that dV1 / dt1 calculated as described above has a high correlation with the internal resistance of the storage battery. This fact is utilized to perform the determination in step S705, described below.

[0031] dV2 / dt2 is calculated as the voltage change per unit time in a range from t2 to t1. Specifically, this corresponds to the voltage change per unit time in range (2) in FIG. 6. This range is where the influence of the negative electrode is most pronounced. dt2 can be appropriately set within the range from t1 to t2 depending on the type of battery, device, application, measurement accuracy, etc. The inventors have found that dV2 / dt2 calculated as described above is highly correlated with the deterioration state of the negative electrode of the storage battery. In this embodiment 1, this fact is utilized to perform the determination in step S303.

[0032] Cole-Cole plots cannot be obtained for all frequencies, and some parts may be missing, as shown by the dotted lines in Figure 6. If it is necessary to use the dotted lines, you can use any interpolation calculation to fill in the values.

[0033] Fig. 7 is a diagram showing the change over time of the battery voltage during the rest period after charging. dV0 / dt0, dV1 / dt1, and dV2 / dt2 can also be obtained from the change over time of the current and voltage output by the battery 200 after charging, in the same manner as described with reference to Figs. 4 to 6. This also applies to the following embodiments.

[0034] <First embodiment: Summary> The battery diagnostic device 100 according to the first embodiment uses dV0 / dt0 during a rest period after charging or discharging to determine whether the battery 200 is Rank C, and uses dV2 / dt2 to determine whether the battery is Rank B. These diagnoses can be performed within, for example, several tens of milliseconds from the start of the rest period. Therefore, the detailed state of the battery 200 can be diagnosed quickly.

[0035] In conventional technology, the SoH may be determined from the internal resistance of a battery, for example. However, in recent years, storage batteries with low internal resistance have become mainstream, making it difficult to determine the degradation state or detailed SoH state based solely on the difference in internal resistance. The diagnostic procedure in this embodiment is useful in that it can diagnose the detailed state even for storage batteries with an internal resistance of 1 mΩ or less.

[0036] <Embodiment 2> 8 is a flowchart illustrating the procedure for diagnosing a battery 200 by a battery diagnostic device 100 according to the second embodiment of the present invention. In the second embodiment, if the battery is not determined to be Rank B in S303, S601 is further performed. The other configurations are the same as those of the first embodiment.

[0037] (Figure 8: Step S601) Using the phase-frequency characteristics of the voltage change amount calculated in step S301, calculation unit 120 determines whether dendrites have occurred in the electrodes of battery 200. For example, if the phase in the phase-frequency characteristics is decreased by a threshold or more from the reference value in the frequency range of f3 or less in Figure 5, it is determined that dendrites have occurred. If these conditions are not met, it is determined as Rank A.

[0038] (Figure 8: Step S601: Supplement) The inventors have found that the phase in the frequency range below f3 is affected by the reaction of the diffusion resistor in the battery 200 and serves as an indicator of dendrite formation. This step utilizes this fact to determine the presence or absence of dendrites. Since batteries with dendrites are at risk of fire due to short circuits, etc., continued use is determined based on safety considerations. For example, the calculation unit 120 may determine the risk of dendrites based on the degree to which the phase has decreased from a reference value and display this information on the UI 130.

[0039] Figure 9 shows a state in which the phase in the phase-frequency characteristics varies significantly from the reference value in the frequency range below f3. If the phase falls below the reference value (solid line) by more than a threshold, as shown by the dotted line in Figure 9, it can be determined that dendrites have occurred. The reference value indicated by the solid line can be obtained, for example, by measuring a normal battery in advance.

[0040] <Third Embodiment> In a third embodiment of the present invention, a temperature band is determined for a battery 200 that was not determined as Rank C or Rank B in the first embodiment. The temperature band is defined as the temperature environment that was most dominant in the deterioration of the battery 200, such as the temperature band that was the longest in the past usage environment of the battery 200, or the temperature band that accelerated the deterioration of the storage battery even for a moment.

[0041] 10 is a flowchart illustrating the procedure for diagnosing a battery 200 by a battery diagnostic device 100 according to a third embodiment of the present invention. In the third embodiment, if the battery is not determined to be Rank B in S303, steps S701 to S705 are further performed. S601 may or may not be performed. The other configurations are the same as those of the first and second embodiments.

[0042] (Figure 10: Step S701) The calculation unit 120 classifies the battery 200 according to the positive electrode material and negative electrode material of the battery 200. An example of classification will be described later. Here, it is assumed that the battery 200 is classified into one of types 1 to 4.

[0043] (Figure 10: Steps S702 to S705) The calculation unit 120 performs a temperature band determination corresponding to the classification result of S701. For type 1, S702 is performed, for type 2, S703 is performed, for type 3, S704 is performed, and for type 4, S705 is performed. Different temperature band determination processes may be performed for each type of battery 200, or the same determination process may be performed for any type. Details of each step will be described later.

[0044] Figure 11 shows examples of combinations of positive and negative electrode materials. For example, the following combinations are possible: Battery type 1: positive electrode material A (lithium manganese oxide) and negative electrode material E (graphite); Battery type 2: positive electrode material B (lithium-nickel-manganese-cobalt oxide) and negative electrode material E; Battery type 3: positive electrode material C (lithium iron phosphate) and negative electrode material E; Battery type 4: positive electrode material D (lithium manganese oxide) and negative electrode material F (lithium titanate). Batteries other than these four types can also be classified based on the combination of various electrode materials.

[0045] FIG. 12 shows examples of temperature bands. The temperature bands have different definitions depending on the battery type. For types 1 and 2, the temperature bands and C-rates have the relationship shown in the upper part of FIG. 12. For type 3, the temperature bands and C-rates have the relationship shown in the middle part of FIG. 12. For type 4, the temperature bands, internal resistance, and dV1 / dt1 have the relationship shown in the lower part of FIG. 12. In steps S702 to S705, the temperature band is determined according to these relationships.

[0046] In S702, if the amplitude on the low frequency side in the amplitude frequency characteristics calculated in S301 has increased relative to the reference value, the temperature band of battery 200 is determined to be temperature band B. If there is no increase in amplitude, the temperature band is determined to be temperature band A. Examples of the amplitude frequency characteristics in this step will be described later.

[0047] In S703, the temperature range is not distinguished for Type 2 batteries. This is because Type 2 batteries tend to deteriorate with the same activation energy regardless of whether they are in temperature range A or B, so there is no need to distinguish between temperature ranges when applying the acceleration factor described below. Furthermore, the relationship between dV2 / dt2 and SoH can be found regardless of the temperature range, so this can be used to estimate the SoH, as described below. In this respect, there is also no need to distinguish between temperature ranges for Type 2 batteries.

[0048] In S704, if the amplitude on the low frequency side of the amplitude frequency characteristic calculated in S301 has increased relative to the reference value, the temperature band of battery 200 is determined to be temperature band E. If there is no increase in amplitude, the temperature band is determined to be temperature band D. An example of the amplitude frequency characteristic in this step is the same as the example in S702.

[0049] FIG. 13 shows an example of the amplitude-frequency characteristics used in S702 and S704. If battery 200 deteriorates primarily due to its use in temperature range B or E, the effects will be apparent in the reactions of the positive electrode and the diffusion resistance. Therefore, if the amplitude on the low frequency side below f2 increases by more than a threshold value relative to the reference value, as shown by the dotted line in FIG. 13, it can be determined that battery 200 has been used in temperature range B or E. The reference value (solid line) may be obtained in advance, for example, by actual measurement.

[0050] 14 is a flowchart illustrating the procedure for determining the temperature band in S705. The calculation unit 120 acquires in advance first data describing the relationship between dV0 / dt0 and the internal resistance, and second data describing the relationship between dV1 / dt1 (the third time rate of change of the third difference) and the internal resistance in each temperature band (F to H in the example of FIG. 12). For example, the data may be stored in advance in a storage device provided in the battery diagnostic device 100.

[0051] The calculation unit 120 estimates the internal resistance of the battery 200 by referring to the first data using dV0 / dt0. Furthermore, the calculation unit 120 estimates the temperature band of the battery 200 by referring to the second data using dV1 / dt1 and the estimated internal resistance. Missing portions of the second data may be interpolated. For example, if dV1 / dt1 and the internal resistance corresponding to the region between temperature bands G and H are obtained, the temperature band between temperature bands G and H may be calculated appropriately by interpolation.

[0052] In addition to the above, the calculation unit 120 may estimate the C rate previously used in the battery 200 according to the relationship in Figure 12. Specifically, by using the temperature band estimated by the above procedure and referring to data describing the relationship in Figure 12 (temperature band data), the C rate previously used for the battery can be estimated. For example, if it is estimated that the temperature band of a Type 3 battery is D, it can be estimated that the C rate previously used for the battery was roughly constant. If it is estimated that it is temperature band C or E, it can at least be estimated that the C rate may not have been constant.

[0053] In addition to the above, the calculation unit 120 may acquire data describing the correlation between dV2 / dt2 and SoH in each temperature range, and estimate the SoH for batteries classified into each temperature range by referring to this data using dV2 / dt2. Furthermore, by applying an acceleration factor corresponding to each temperature range, it is possible to predict the remaining life of the battery 200. The acceleration factor is set using a previously created Eyring plot, etc.

[0054] <Fourth Embodiment> 15 shows another example of the configuration of the battery diagnostic device 100. The detection unit 110 may communicate with the calculation unit 120 via a network via the communication unit 140. The calculation unit 120 may also learn the measurement results of multiple batteries and update each of the determination criteria. The other configurations are the same as those of the first to third embodiments.

[0055] <Modifications of the present invention> The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0056] In the above embodiments, the detection unit 110 and the calculation unit 120 can be configured by hardware such as a circuit device that implements their functions, or by a calculation device such as a CPU (Central Processing Unit) that executes software that implements their functions.

[0057] In the above embodiment, it is desirable that t2 be set within a few seconds from the start time of the rest period at the latest. The specific value of t2 varies depending on the individual battery and battery type, so it may be set appropriately depending on these. [Explanation of symbols]

[0058] 100: Battery diagnostic device 110: Detection unit 120: Arithmetic section 130:UI 200:Battery

Claims

1. A battery diagnostic device for diagnosing the state of a battery, a detection unit that acquires a detected value of the voltage output by the battery; a calculation unit that estimates the state of the battery using the difference that represents the change in the voltage over time; Equipped with the calculation unit determines whether the battery is in a first state based on a first difference between the voltage at a first calculation point after an end point at which charging or discharging of the battery is completed and the voltage at a first point when a first period of time within 4 msec has elapsed from the end point, the calculation unit determines whether the battery is in a second state by using, as the difference, a second difference between the voltage at a second time point after the first time point and the voltage at a second time point when a second period has elapsed since the second time point; The second period is a section between a frequency of an inflection point where a phase gradient changes from negative to positive in a phase-frequency characteristic obtained by Fourier transforming the change over time of the voltage after the end point, and a frequency corresponding to a time constant of a negative electrode of the battery. or the second period is within a range of an interval delimited by an inflection point when the change in the voltage over time after the end point is represented on a logarithmic time axis; A battery diagnostic device characterized by:

2. A battery diagnostic device for diagnosing the state of a battery, a detection unit that acquires a detected value of the voltage output by the battery; a calculation unit that estimates the state of the battery using the difference that represents the change in the voltage over time; Equipped with the calculation unit determines whether the battery is in a first state based on a first difference between the voltage at a first calculation point after an end point at which charging or discharging of the battery is completed and the voltage at a first point when a first period of time within 4 msec has elapsed from the end point, the calculation unit determines whether the battery is in a second state by using, as the difference, a second difference between the voltage at a second time point after the first time point and the voltage at a second time point when a second period has elapsed since the second time point; When the calculation unit determines that the battery is in the first state, it outputs a determination result that the battery is in a state where it is unable to be charged or discharged due to an abnormal voltage or resistance, or in a state immediately before that state; When the calculation unit determines that the battery is in the second state, it outputs a determination result indicating that the battery is in a state where deterioration of the battery is accelerating and a rapid decrease in SoH is observed, or a state immediately before that. A battery diagnostic device characterized by:

3. A battery diagnostic device for diagnosing the state of a battery, a detection unit that acquires a detected value of the voltage output by the battery; a calculation unit that estimates the state of the battery using the difference that represents the change in the voltage over time; Equipped with the calculation unit determines whether the battery is in a first state based on a first difference between the voltage at a first calculation point after an end point at which charging or discharging of the battery is completed and the voltage at a first point when a first period of time within 4 msec has elapsed from the end point, the calculation unit determines whether the battery is in a second state by using, as the difference, a second difference between the voltage at a second time point after the first time point and the voltage at a second time point when a second period has elapsed since the second time point; The calculation unit calculates a relationship between the occurrence rate of each of the first state and the second state and the cumulative usage time of the battery, a region where the incidence rate decreases with the cumulative usage time; a region in which the incidence rate is constant regardless of the cumulative usage time; a region where the incidence rate increases with the cumulative usage time; is defined by The calculation unit determines, according to the definition, at least one of whether the battery can be continued to be used or the occurrence rates of the first state and the second state. A battery diagnostic device characterized by:

4. A battery diagnostic device for diagnosing the state of a battery, a detection unit that acquires a detected value of the voltage output by the battery; a calculation unit that estimates the state of the battery using the difference that represents the change in the voltage over time; Equipped with the calculation unit determines whether the battery is in a first state based on a first difference between the voltage at a first calculation point after an end point at which charging or discharging of the battery is completed and the voltage at a first point when a first period of time within 4 msec has elapsed from the end point, the calculation unit determines whether the battery is in a second state by using, as the difference, a second difference between the voltage at a second time point after the first time point and the voltage at a second time point when a second period has elapsed since the second time point; the calculation unit acquires a phase frequency characteristic obtained by Fourier transforming a measurement result of the change over time of the voltage after the end time point; The calculation unit determines that dendrites are occurring inside the battery when the phase of a region corresponding to a diffused resistor included in the battery in the phase-frequency characteristics is decreased by a threshold value or more with respect to a reference value. A battery diagnostic device characterized by:

5. A battery diagnostic device for diagnosing the state of a battery, a detection unit that acquires a detected value of the voltage output by the battery; a calculation unit that estimates the state of the battery using the difference that represents the change in the voltage over time; Equipped with the calculation unit determines whether the battery is in a first state based on a first difference between the voltage at a first calculation point after an end point at which charging or discharging of the battery is completed and the voltage at a first point when a first period of time within 4 msec has elapsed from the end point, the calculation unit determines whether the battery is in a second state by using, as the difference, a second difference between the voltage at a second time point after the first time point and the voltage at a second time point when a second period has elapsed since the second time point; the calculation unit determines whether the type of the battery is a first type, a second type, a third type, or a fourth type based on the material of the electrodes of the battery; the calculation unit estimates, for each type of battery, a temperature range that is most dominant in battery deterioration; When the battery is the first type, the calculation unit estimates that the temperature band is a first temperature band if, in an amplitude-frequency characteristic obtained by Fourier transforming the change over time of the voltage after the end time point, the amplitude of a region corresponding to a positive electrode of the battery increases by a threshold value or more with respect to a reference value, and estimates that the temperature band is less than the first temperature band if the amplitude does not increase; the calculation unit does not estimate the temperature band when the battery is of the second type, When the battery is the third type, the calculation unit estimates that the temperature band is the second temperature band if, in an amplitude-frequency characteristic obtained by Fourier transforming the change in the voltage over time after the end point, the amplitude of a region corresponding to a positive electrode of the battery increases by a threshold value or more with respect to a reference value, and estimates that the temperature band is less than the second temperature band if the amplitude does not increase; When the battery is the fourth type, the calculation unit estimates an internal resistance of the battery according to the first difference, and estimates the temperature band using the estimated internal resistance. A battery diagnostic device characterized by:

6. the calculation unit determines that the battery is in the first state when a first time rate of change of the first difference is equal to or greater than a first threshold; the calculation unit measures the second time rate of change of the second difference a plurality of times; The calculation unit determines that the battery is in the second state when the variation between the second time rates of change is equal to or greater than a second threshold value, or when the charging voltage of the battery exceeds the discharging voltage.

6. The battery diagnostic device according to claim 1, wherein the battery diagnostic device is a battery diagnostic device.

7. When the calculation unit determines that the battery is not in the first state or the second state, it outputs a determination result that the battery is in a state where it can be used normally; When the calculation unit determines that the battery is in the first state or the second state, it outputs a notification recommending that the battery be replaced even if the accumulated usage time of the battery has not reached a predetermined usable time.

6. The battery diagnostic device according to claim 1, wherein the battery diagnostic device is a battery diagnostic device.

8. the calculation unit estimates a relationship between an SoH value and the number of the batteries having the SoH value for the plurality of batteries determined to be in the second state according to a normal distribution; The calculation unit quantifies the quality of the battery using the standard deviation of the normal distribution.

6. The battery diagnostic device according to claim 1, wherein the battery diagnostic device is a battery diagnostic device.

9. the calculation unit obtains a third time rate of change of the third difference of the voltage during a period between the first difference and the second difference; the calculation unit obtains a correspondence relationship between the internal resistance of the battery, the third time rate of change, and the temperature range; The calculation unit estimates the temperature range by referring to the correspondence relationship using the estimated internal resistance and the third time rate of change.

6. The battery diagnostic device according to claim 5.

10. the first type of battery is composed of a first cathode material and a first anode material; the second type of battery is composed of a second cathode material and the first anode material, the third type of battery is composed of a third cathode material and the first anode material, The fourth type of battery is composed of a fourth cathode material and a second anode material.

6. The battery diagnostic device according to claim 5.

11. the calculation unit acquires temperature band data describing a relationship between the temperature band and a C rate to be used in each of the first, second, and third types; the temperature range data describes that the C rate during charging and discharging is constant for the first type and the second type of the batteries regardless of the temperature range; the temperature band data describes that, for the third type of battery, in the second temperature band, the C rate during charge and discharge decreases with increasing temperature, in a third temperature band lower than the second temperature band, the C rate during charge and discharge is constant, and in a fourth temperature band lower than the third temperature band, the C rate during charge and discharge decreases with decreasing temperature; The calculation unit estimates a C-rate previously used for the battery by referring to the temperature band data using the estimated temperature band.

6. The battery diagnostic device according to claim 5.

12. The calculation unit estimates the remaining life of the battery by applying an acceleration constant corresponding to the estimated temperature range.

6. The battery diagnostic device according to claim 5.

13. A battery diagnostic method for diagnosing a battery state, comprising: obtaining a detected value of the voltage output from the battery; estimating the state of the battery using the difference representing the change in voltage over time; and In the estimating step, whether or not the battery is in a first state is determined based on a first difference between the voltage at a first starting point after an end point at which charging or discharging of the battery is completed and the voltage at a first point when a first period of time within 4 msec has elapsed from the end point, in the estimating step, a second difference between the voltage at a second time point after the first time point and the voltage at a second time point when a second period has elapsed since the second time point is used as the difference to determine whether the battery is in a second state; The second period is a section between a frequency of an inflection point where a phase gradient changes from negative to positive in a phase-frequency characteristic obtained by Fourier transforming the change over time of the voltage after the end point, and a frequency corresponding to a time constant of a negative electrode of the battery. or the second period is within a range of an interval delimited by an inflection point when the change in the voltage over time after the end point is represented on a logarithmic time axis; A battery diagnostic method comprising:

14. A battery diagnostic method for diagnosing a battery state, comprising: obtaining a detected value of the voltage output from the battery; estimating the state of the battery using the difference representing the change in voltage over time; and In the estimating step, whether or not the battery is in a first state is determined based on a first difference between the voltage at a first starting point after an end point at which charging or discharging of the battery is completed and the voltage at a first point when a first period of time within 4 msec has elapsed from the end point, in the estimating step, a second difference between the voltage at a second time point after the first time point and the voltage at a second time point when a second period has elapsed since the second time point is used as the difference to determine whether the battery is in a second state; In the step of estimating, when it is determined that the battery is in the first state, a determination result is output indicating that the battery is in a state where it is unable to be charged or discharged due to an abnormal voltage or an abnormal resistance, or in a state immediately before such a state; In the step of estimating, when it is determined that the battery is in the second state, a determination result is output to the effect that the battery is in a state where deterioration of the battery is accelerating and a rapid decrease in SoH is observed, or a state immediately before that. A battery diagnostic method comprising:

15. A battery diagnostic method for diagnosing a battery state, comprising: obtaining a detected value of the voltage output from the battery; estimating the state of the battery using the difference representing the change in voltage over time; and In the estimating step, whether or not the battery is in a first state is determined based on a first difference between the voltage at a first starting point after an end point at which charging or discharging of the battery is completed and the voltage at a first point when a first period of time within 4 msec has elapsed from the end point, in the estimating step, a second difference between the voltage at a second time point after the first time point and the voltage at a second time point when a second period has elapsed since the second time point is used as the difference to determine whether the battery is in a second state; In the step of estimating, a relationship between the occurrence rate of each of the first state and the second state and the cumulative usage time of the battery is calculated by: a region where the incidence rate decreases with the cumulative usage time; a region in which the incidence rate is constant regardless of the cumulative usage time; a region where the incidence rate increases with the cumulative usage time; is defined by In the step of estimating, at least one of whether the battery can be continued to be used or the occurrence rate of each of the first state and the second state is determined according to the definition. A battery diagnostic method comprising:

16. A battery diagnostic method for diagnosing a battery state, comprising: obtaining a detected value of the voltage output from the battery; estimating the state of the battery using the difference representing the change in voltage over time; and In the estimating step, whether or not the battery is in a first state is determined based on a first difference between the voltage at a first starting point after an end point at which charging or discharging of the battery is completed and the voltage at a first point when a first period of time within 4 msec has elapsed from the end point, in the estimating step, a second difference between the voltage at a second time point after the first time point and the voltage at a second time point when a second period has elapsed since the second time point is used as the difference to determine whether the battery is in a second state; In the estimating step, a phase frequency characteristic is obtained by Fourier transforming a measurement result of the change in the voltage over time after the end time point; In the estimating step, if the phase of a region corresponding to a diffused resistor included in the battery in the phase-frequency characteristics is decreased by a threshold value or more with respect to a reference value, it is determined that dendrites are occurring inside the battery. A battery diagnostic method comprising:

17. A battery diagnostic method for diagnosing a battery state, comprising: obtaining a detected value of the voltage output from the battery; estimating the state of the battery using the difference representing the change in voltage over time; and In the estimating step, whether or not the battery is in a first state is determined based on a first difference between the voltage at a first starting point after an end point at which charging or discharging of the battery is completed and the voltage at a first point when a first period of time within 4 msec has elapsed from the end point, in the estimating step, a second difference between the voltage at a second time point after the first time point and the voltage at a second time point when a second period has elapsed since the second time point is used as the difference to determine whether the battery is in a second state; In the step of estimating, a type of the battery is determined to be one of a first type, a second type, a third type, and a fourth type based on a material of an electrode included in the battery; In the step of estimating, a temperature range that is most dominant in deterioration of the battery is estimated for each type of the battery; In the estimating step, if the battery is of the first type, when the amplitude of a region corresponding to a positive electrode of the battery increases by a threshold or more with respect to a reference value in an amplitude-frequency characteristic obtained by Fourier transforming the change in the voltage over time after the end time point, the temperature band is estimated to be a first temperature band, and when the amplitude does not increase, the temperature band is estimated to be less than the first temperature band; In the estimating step, if the battery is the second type, the temperature band is not estimated, In the estimating step, if the battery is of the third type, when the amplitude of a region corresponding to a positive electrode of the battery increases by a threshold or more with respect to a reference value in an amplitude-frequency characteristic obtained by Fourier transforming the change in the voltage over time after the end time point, the temperature band is estimated to be a second temperature band, and when the amplitude does not increase, the temperature band is estimated to be less than the second temperature band; In the estimating step, if the battery is of the fourth type, an internal resistance of the battery is estimated according to the first difference, and the temperature band is estimated using the estimated internal resistance. A battery diagnostic method comprising:

18. The diagnosis is performed on the battery whose internal resistance is 1 mΩ or less.

18. The battery diagnostic method according to claim 13, wherein:

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