CN118414552A - Electronic device and measuring method - Google Patents

Abstract

An electronic device according to one aspect of the present technology includes a voltage difference deriving unit, which derives a difference between a first voltage value and a second voltage value based on a voltage value obtained by voltage measurement, wherein the first voltage value is a voltage value before the current is changed in a step-like manner, and the second voltage value is a voltage value after the current is changed in a step-like manner. The voltage difference deriving unit derives at least two of the following three differences: a first difference between the first voltage value and a third voltage value, wherein the third voltage value is a voltage value after the component of the second voltage value is changed due to the body resistance of the battery; a second difference between the first voltage value and a fourth voltage value, wherein the fourth voltage value is a voltage value after the component of the second voltage value is changed due to the charge transfer resistance of the battery; and a third difference between the first voltage value and a fifth voltage value, wherein the fifth voltage value is a voltage value after the component of the second voltage value is changed due to the diffusion resistance of the battery.

Description

Electronic device and measuring method

Technical Field

The present technology relates to electronic equipment and measurement methods.

Background technique

In recent years, the use of secondary batteries has expanded to larger-scale equipment such as electric vehicles and energy storage systems. The larger the scale, the greater the damage in the event of a fire, so the importance of developing technologies to improve safety is increasing. In addition, it is important to properly understand the abnormal behavior and degradation of secondary batteries.

In Patent Document 1, the current is cut off during charging and discharging, and the presence or absence of degradation is detected based on the voltage change at this time. Here, in Patent Document 1, the presence or absence of degradation is detected by comparing the voltage change in the initial state with the voltage change during use, that is, by relative evaluation. Therefore, compared with the case of performing absolute evaluation, it is not necessary to perform a large number of experiments to define the evaluation criteria (such as threshold values) of degradation, and excellent operation is achieved.

Prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Publication No. 2016-176924

Summary of the invention

However, there is a problem that it is difficult to make a comprehensive determination of what kind of specific degradation has occurred in Patent Document 1. It is desirable to provide an electronic device and a measuring method that can make a comprehensive determination.

The electronic device involved in the first aspect of the present technology comprises a current supply unit, a voltage measuring unit and a voltage difference derivation unit. The current supply unit is capable of supplying a current that changes in a step-like manner to a battery. The voltage measuring unit measures the voltage of the battery. The voltage difference derivation unit is capable of deriving a difference between a first voltage value and a second voltage value based on a voltage value obtained by measurement by the voltage measuring unit, wherein the first voltage value is a voltage value before the current is changed in a step-like manner by the current supply unit, and the second voltage value is a voltage value after the current is changed in a step-like manner by the current supply unit. The voltage difference derivation unit is capable of deriving at least two of the following three differences,

a first difference between the first voltage value and a third voltage value, the third voltage value being a voltage value after a component change of the second voltage value caused by a body resistance of the battery;

a second difference between the first voltage value and a fourth voltage value, the fourth voltage value being a voltage value after a component change of the second voltage value caused by a charge transfer resistance of the battery; and

A third difference between the first voltage value and a fifth voltage value, the fifth voltage value being a voltage value after a component change of the second voltage value caused by a diffusion resistance of the battery.

The second aspect of the present technology involves the following three measurement methods.

(A) Supplying a step-by-step current to the battery

(B) Measure the battery voltage

(C) deriving a difference between a first voltage and a second voltage based on the voltage value obtained by the measurement, wherein the first voltage is a voltage value before the current flowing to the battery is changed in a step-like manner, and the second voltage is a voltage value after the current flowing to the battery is changed in a step-like manner in the current supply process.

When deriving differences, derive at least two of the following three differences,

a first difference between the first voltage value and a third voltage value, the third voltage value being a voltage value after a component change of the second voltage value caused by a body resistance of the battery;

a second difference between the first voltage value and a fourth voltage value, the fourth voltage value being a voltage value after a component change of the second voltage value caused by a charge transfer resistance of the battery; and

A third difference between the first voltage value and a fifth voltage value, the fifth voltage value being a voltage value after a component change of the second voltage value caused by a diffusion resistance of the battery.

According to the electronic device involved in the first aspect of the present technology and the measurement method involved in the second aspect of the present technology, the difference between the first voltage and the second voltage value is derived based on the voltage value obtained by voltage measurement, the first voltage value is the voltage value before the current flowing to the battery is changed in a step-like manner, and the second voltage value is the voltage value after the current flowing to the battery is changed in a step-like manner. When deriving the difference, at least two of the following three differences are derived, so that at least two circuit constants in the equivalent circuit of the battery can be derived using the derived at least two differences. As a result, the degradation mode of the battery can be judged in many aspects using the derived at least two circuit constants.

It should be noted that the effects of the present technology are not necessarily limited to the effects described here, and may be any effect in a series of effects related to the present technology described later.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a functional block example of an analysis device according to an embodiment of the present technique.

Fig. 2(A) is a diagram showing an example of a waveform of a current supplied to a battery, and Fig. 2(B) is a diagram showing an example of a waveform of a voltage of a battery.

FIG. 3 is a diagram showing an equivalent circuit of a secondary battery that is an analysis target of the analysis device of FIG. 1 .

FIG. 4 is a diagram showing an example of an analysis procedure in the analysis device of FIG. 1 .

FIG. 5 is a diagram showing an example of analysis results obtained by the analysis device of FIG. 1 .

FIG. 6 is a diagram showing an example of analysis results obtained by the analysis device of FIG. 1 .

FIG. 7 is a diagram showing an example of analysis results by the analysis device of FIG. 1 .

FIG. 8 is a diagram showing an example of analysis results obtained by the analysis device of FIG. 1 .

FIG. 9 is a diagram showing a modified example of the functional blocks of the analysis device according to one embodiment of the present technique.

FIG. 10 is a diagram showing a modified example of the functional blocks of the analysis device according to one embodiment of the present technique.

Detailed ways

Hereinafter, a mode for implementing the present technology will be described in detail with reference to the drawings.

＜1. Implementation Method＞

[structure]

The structure of an analysis device 10 involved in an embodiment of the present technology is described. The analysis device 10 is a device that analyzes the degradation state of a secondary battery. In this embodiment, the secondary battery that is the analysis object of the analysis device 10 is a battery pack 20. The battery pack 20 is, for example, a lithium-ion secondary battery. The battery pack 20 is composed of a plurality of single cells 21. Each single cell 21 can be a unit cell or a battery block in which a plurality of unit cells are connected. In each single cell 21, a plurality of secondary batteries can be connected in series or in parallel.

As shown in FIG. 1 , the analysis device 10 includes a current supply unit 11 , a voltage measurement unit 12 , a current measurement unit 13 , a voltage difference derivation unit 14 , a circuit constant calculation unit 15 , and a multivariate analysis unit 16 .

The current supply unit 11 is a device that discharges or charges the battery pack 20 provided in the analysis device 10. As charging, the current supply unit 11 can perform CCCV charging, for example. The current supply unit 11 changes the current supplied to the battery pack 20 in a stepwise manner, for example, during CCCV charging (current supply process S102 in FIG. 4 ). The current supply unit 11 has a charging circuit including, for example, a generator and a converter. The charging circuit controls the voltage for charging the battery pack 20.

The voltage measuring unit 12 has a measuring circuit for measuring the voltage of each single cell 21 included in the battery pack 20. It should be noted that, although FIG. 1 illustrates a structure in which wiring is connected to the positive and negative electrodes of each single cell 21 and the voltage of each single cell 21 is measured by measuring the voltage obtained through the wiring, the method for measuring the voltage of each single cell 21 is not limited to this method. The voltage measuring unit 12 outputs data (voltage value) on the voltage measured by the measuring circuit to the voltage difference derivation unit 14. The voltage measuring unit 12 measures the voltage of each single cell 21 during and after the charging or discharging of the battery pack 20 (the first voltage measuring step S101 and the second voltage measuring step S103 in FIG. 4).

The current measuring unit 13 has a measuring circuit for measuring the current of each single cell 21 included in the battery pack 20. It should be noted that, although FIG. 1 illustrates a structure in which wiring is connected to the positive and negative electrodes of the battery pack 20, and the current of each single cell 21 is measured by measuring the current obtained through the wiring, the method for measuring the current of each single cell 21 is not limited to this method. The current measuring unit 13 outputs data (current value) on the current measured by the measuring circuit to the voltage difference derivation unit 14. The current measuring unit 13 measures the current of each single cell 21 (i.e., the current of the battery pack 20) during and after the charging or discharging of the battery pack 20.

The voltage difference deriving unit 14 derives, for each single cell 21, a difference between a voltage value Vo (first voltage value) before the current supply unit 11 changes the current in a step-like manner and a voltage value (second voltage value) after the current supply unit 11 changes the current in a step-like manner, based on the voltage value measured by the voltage measuring unit 12 (voltage difference deriving step S104 in FIG. 4 ). Specifically, the voltage difference deriving unit 14 derives at least two of the following three differences for each single cell 21, for example, as shown in FIG. 2 . The voltage difference deriving unit 14 derives, for example, (1) a difference Va and a difference Vc, (2) a difference Vb and a difference Vc, or (3) a difference Va, a difference Vb, and a difference Vc for each single cell 21.

The difference Va (first difference) between the voltage value Vo and the voltage value V1 (third voltage value) after the component change of the second voltage value caused by the body resistance of the battery 21 is obtained (Va=|Vo-V1|).

The difference Vb (second difference) (Vb=|Vo-V2|) between the voltage value Vo and the voltage value V2 (fourth voltage value) after the component change of the second voltage value caused by the charge transfer resistance of the single cell 21

The difference Vc (third difference) between the voltage value Vo and the voltage value V3 (fifth voltage value) after the component change of the second voltage value caused by the diffusion resistance of the single cell 21 (Vc=|Vo-V3|) is

The voltage difference deriving unit 14 derives the difference value Va from the voltage value in a period of 1 μs or more and less than 1 ms after the current supply unit 11 causes the current to change in a step-like manner as the voltage value V1. The voltage difference deriving unit 14 derives the difference value Vb from the voltage value in a period of 1 ms or more and less than 10 s after the current supply unit 11 causes the current to change in a step-like manner as the voltage value V2. The voltage difference deriving unit 14 derives the difference value Vc from the voltage value in a period of 10 s or more and less than 100,000 s after the current supply unit 11 causes the current to change in a step-like manner as the voltage value V2.

The circuit constant calculation unit 15 uses each voltage value and current value derived by the voltage difference derivation unit 14 during the charging or discharging process (before the current is changed in a step-like manner) and after the implementation (after the current is changed in a step-like manner) of each single cell 21, and calculates at least two circuit constants in the equivalent circuit of the single cell 21 for each single cell 21 (circuit constant calculation step S105 in Figure 4).

Fig. 3 shows an equivalent circuit of each cell 21. As shown in Fig. 3, each cell 21 is represented by an equivalent circuit consisting of a bulk resistance Rs having a time constant τa of 1 μs or more and less than 1 ms, a charge transfer resistance Rct having a time constant τb of 1 ms or more and less than 10 s, and a diffusion resistance Rd having a time constant τc of 10 s or more and less than 100,000 s.

The circuit constant calculation unit 15 calculates the bulk resistance Rs (impedance parameter) by dividing the difference Va by the current value Io during charging or discharging (before the current is changed in a step-like manner). The circuit constant calculation unit 15 calculates the sum of the bulk resistance Rs and the charge transfer resistance Rct (impedance parameter) by dividing the difference Vb by the current value Io. The circuit constant calculation unit 15 calculates the sum of the bulk resistance Rs, the charge transfer resistance Rct, and the diffusion resistance Rd (impedance parameter) by dividing the difference Vc by the current value Io.

Here, the bulk resistance Rs, the charge transfer resistance Rct, and the diffusion resistance Rd generally have the following relationship.

Rs＜Rct＜Rd

Therefore, the circuit constant (impedance parameter) calculated using the difference Vb mainly depends on the charge transfer resistance Rct. In addition, the circuit constant (impedance parameter) calculated using the difference Vc mainly depends on the diffusion resistance Rd. Therefore, the three circuit constants (impedance parameters) calculated by the circuit constant calculation unit 15 are not completely independent of each other, but can be said to be highly independent of each other. Therefore, based on the three circuit constants (impedance parameters) calculated by the circuit constant calculation unit 15, it can be determined whether the degradation of the single cell 21 is as expected or abnormal.

The multivariate analysis unit 16 derives the distribution information of at least two circuit constants (impedance parameters) in the plurality of cells 21, and uses the distribution information thus obtained to perform multivariate analysis (multivariate analysis step S106 in FIG. 4 ). As a method of multivariate analysis, the multivariate analysis unit 16 uses, for example, the Mahal-Taguchi method or the one-class support vector machine method. The multivariate analysis using the Mahal-Taguchi method is described in detail below. The multivariate analysis unit 16 derives the abnormality ai for each cell 21, for example, by performing the following multivariate analysis.

(Adjustment of the lithium-ion battery as a sample)

15 commercially available lithium-ion batteries US18650FTC1 (rated capacity 1.05Ah) whose main positive electrode active material is lithium iron phosphate (LiFePO4, LFP) and whose main negative electrode active material is graphite were prepared. These are all products of the same manufacturing batch. For 12 of them, constant current discharge was first performed at a current value equivalent to 0.2 hour rate (the rated capacity is 1.05Ah, the current value It at 1 hour rate is 1.05A, so the current value I at 0.2 hour rate is 0.2I=210mA) until the voltage is lower than 2.0V, and then CCCV charging (a two-step charging with a set current value of 1.05A (=1It) and a set voltage of 3.6V) was quickly performed, and the charging was stopped 2.5h after the start of charging. The 12 lithium-ion batteries were placed in a thermostatic chamber set at 12 different temperatures, 35° C., 40° C., ..., and 90° C., respectively, while being kept in a fully charged state, and stored for 25 days to deteriorate.

(Calculation of circuit constants)

For the 15 prepared lithium-ion batteries, the voltage difference was measured three or less times for each of the three lithium-ion batteries that had not undergone the above-mentioned degradation process, and the voltage difference was measured only once or less for each of the 12 lithium-ion batteries that had undergone the above-mentioned degradation process.

The sample was placed in a constant temperature bath at 23°C, and CCCV charging was performed with a set current of 1.05A (=1It) and a set voltage of 3.6V. The CCCV charging was stopped at the time point when the current value in the constant voltage charging was lower than 105mA (=0.1It). That is, the current value Io just before the current was cut off was 105mA. The voltage just before the current was cut off was measured and taken as Vo. In addition, the voltages 0.6ms, 60ms, and 1h after the cut-off were measured and taken as V1, V2, and V3, respectively. In addition, (V1-Vo)/Io obtained by dividing the first voltage difference by the current value is set to Rs, (V2-Vo)/Io-Rs obtained by dividing the second voltage difference by the current value and then subtracting Rs is set to Rct, and (V3-Vo)/Io obtained by dividing the third voltage difference by the current value is set to Rdc. It should be noted that Rdc is the sum of the body resistance Rs, the charge transfer resistance Rct, and the diffusion resistance Rd.

(Multivariate analysis)

As shown in the following formula (1), nine sets of data (each including three circuit constants (impedance parameters)) obtained by performing three AC impedance measurements on three lithium-ion batteries that have not undergone the above-mentioned degradation process are defined as nine vectors xi (i is an integer from 1 to 9).

[Mathematical formula 1]

Next, the vector μ and the variance-covariance matrix Σ of the average values of the nine sets of data of each circuit constant are calculated by equation (2) and equation (3), respectively.

[Mathematical formula 2]

[Mathematical formula 3]

Next, as shown in formula (4), 12 sets of data (each of which includes three circuit constants (impedance parameters)) obtained from 12 lithium-ion batteries that have undergone the above-mentioned degradation process are defined as 12 additional vectors xi (i is an integer from 10 to 21). Then, for all 21 vectors, the abnormality ai is calculated according to formula (5).

[Formula 4]

[Mathematical formula 5]

For comparison, the abnormality degree was calculated without using multiple variables but only using one circuit constant (Figures 5 to 7). In addition, for all results, the threshold for determining abnormality was calculated based on the 95% and 99% quantiles in the F distribution table.

In addition, FIG8 shows the results of the abnormality calculated using three circuit constants (impedance parameters). In all the figures, "A" to "I" on the horizontal axis are data obtained from batteries that have not undergone the above-mentioned degradation process, which corresponds to i=1, 2..., 9 in formula (5). In addition, "J" to "U" on the horizontal axis are data obtained from batteries that have undergone the above-mentioned degradation process, which correspond to i=10, 11,..., 21 in formula (5), respectively. Since "A" to "I" have not undergone the above-mentioned degradation process, they are regarded as data obtained from qualified batteries (normal batteries) in subsequent investigations. On the other hand, "J" to "U" are data obtained from batteries stored at storage temperatures of 35°C, 40°C,..., 90°C, respectively. The closer to Z, the greater the degree of degradation, and they are all regarded as data obtained from unqualified batteries.

According to Figures 5 and 6, no clear difference in abnormality was found between the batteries "A" to "I" considered as qualified products and the batteries "J" to "U" considered as defective products. In other words, it was determined that only using Rs or Rct cannot determine whether a qualified product is a defective product.

According to FIG. 7 , there is a tendency that the abnormality of defective products is high between the batteries "A" to "I" which are considered as qualified products and the batteries "J" to "U" which are considered as defective products. However, relatively high abnormality is detected in "C" and "F" which are considered as qualified products. That is, when only Rdc is used to judge whether a qualified product is defective, the judgment accuracy is insufficient.

According to Fig. 8, there is a clear tendency that the abnormality of defective products is high between the batteries "A" to "I" which are considered as good products and the batteries "J" to "S" which are considered as defective products. That is, it is judged that good judgment can be made by using three circuit constants (impedance parameters).

As described above, the multivariate analysis unit 16 includes at least two circuit constants (impedance parameters) related to the physical phenomenon that causes the transient response as at least two circuit constants (impedance parameters) in the plurality of cells 21 selected in the multivariate analysis. As such circuit constants, the above three circuit constants (impedance parameters) meet the conditions.

[Effect]

Next, the effects of the analysis device 10 will be described.

In recent years, the use of secondary batteries has expanded to larger-scale equipment such as electric vehicles and energy storage systems. The larger the scale, the greater the damage in the event of a fire, so the importance of developing technologies to improve safety is increasing. In addition, it is important to properly understand the abnormal behavior and degradation of secondary batteries during use.

In Patent Document 1, the current is cut off during charging and discharging, and the presence or absence of degradation is detected based on the voltage change at this time. Here, in Patent Document 1, the presence or absence of degradation is detected by comparing the voltage change in the initial state with the voltage change during use, that is, by relative evaluation. Therefore, compared with the case of performing absolute evaluation, it is not necessary to perform a large number of experiments to define the evaluation criteria (such as threshold values) of degradation, and excellent operation is achieved.

On the other hand, in the present embodiment, the difference between the voltage value Vo (first voltage value) before the current flowing to the cell 21 is changed stepwise and the voltage value (second voltage value) after the current flowing to the cell 21 is changed stepwise is derived based on the voltage value measured by the voltage measuring unit 12, and when deriving the difference, at least two of the three differences Va, Vb, and Vc are derived. Thus, using the derived at least two differences, at least two circuit constants (impedance parameters) in the equivalent circuit of the cell 21 can be derived. As a result, using the derived at least two circuit constants (impedance parameters), the degradation mode of the cell 21 can be judged in many aspects.

It should be noted that, in the present embodiment, the multivariate analysis unit 16 may also perform multivariate analysis using the distribution information stored in the storage unit 17, for example, as shown in FIG. 9, instead of the distribution information of at least two circuit constants (impedance parameters) in the plurality of single cells 21. The distribution information stored in the storage unit 17 is the distribution information of at least two circuit constants (impedance parameters) in the plurality of normal cells. The storage unit 17 is, for example, composed of a nonvolatile memory, such as an EEPROM (Electrically Erasable Programmable Read-Only Memory), a flash memory, a resistance variable memory, and the like.

At this time, as two or more circuit constants (impedance parameters) of the plurality of normal batteries selected in the multivariate analysis, for example, at least two of the three circuit constants (impedance parameters) described above meet the condition. As at least two circuit constants (impedance parameters) of the plurality of single batteries 21 selected in the multivariate analysis, for example, (1) Rs and Rd, (2) Rct and Rd, or (3) Rs, Rct, and Rd meet the condition.

It should be noted that, in the present embodiment, the secondary battery that is the object of analysis of the analysis device 10 may be, for example, a single cell 30 as shown in FIG. 10. In this case, the single cell 30 may be a unit cell or a battery block to which a plurality of unit cells are connected. In the single cell 30, a plurality of secondary batteries may be connected in series or in parallel. In addition, at this time, the multivariate analysis unit 16 may, for example, as shown in FIG. 10, replace the distribution information of at least two circuit constants (impedance parameters) in the plurality of single cells 21 with the distribution information stored in the storage unit 17 for multivariate analysis. The distribution information stored in the storage unit 17 is the distribution information of at least two circuit constants (impedance parameters) in the plurality of normal batteries.

The effects described in this specification are merely examples, and therefore the effects of the present technology are not limited to the effects described in this specification. Therefore, other effects can also be obtained with respect to the present technology.

It should be noted that the present technology can also adopt the following structures.

＜1＞

An electronic device comprising:

A current supply unit capable of supplying a step-wise changing current to the battery;

a voltage measuring unit capable of measuring the voltage of the battery; and

a voltage difference deriving unit capable of deriving a difference between a first voltage value and a second voltage value based on a voltage value measured by the voltage measuring unit, wherein the first voltage value is the voltage value before the current is changed stepwise by the current supply unit, and the second voltage value is the voltage value after the current is changed stepwise by the current supply unit.

The voltage difference deriving unit is capable of deriving at least two of the following three difference values:

a first difference between the first voltage value and a third voltage value, the third voltage value being a voltage value after a component change of the second voltage value caused by a body resistance of the battery;

a second difference between the first voltage value and a fourth voltage value, the fourth voltage value being a voltage value after a component change of the second voltage value caused by a charge transfer resistance of the battery; and

A third difference between the first voltage value and a fifth voltage value, the fifth voltage value being a voltage value after a component change of the second voltage value caused by a diffusion resistance of the battery.

＜2＞

The electronic device according to <1>,

The voltage difference deriving unit can derive the first difference value by using a voltage value in a period of 1 μs or more and less than 1 ms after the current supplier changes the current in a step-like manner as the third voltage value.

＜3＞

The electronic device according to <1>,

The voltage difference deriving unit can derive the second difference value by using, as the fourth voltage value, a voltage value within a period of 1 ms or longer and less than 10 s after the current supplier changes the current in a step-like manner.

＜4＞

The electronic device according to <1>,

The voltage difference deriving unit can derive the third difference value by using, as the fifth voltage value, a voltage value within a period of 10 seconds or more and less than 10000 seconds after the current supplier changes the current in a step-like manner.

＜5＞

The electronic device according to <1>,

The battery is a single battery, and the electronic device comprises:

a current measuring unit capable of measuring the current of the battery;

a calculation unit capable of calculating at least two circuit constants in an equivalent circuit of the battery using a current value obtained by the current measurement unit before the current is step-changed by the current supply unit, and at least two of the first difference, the second difference, and the third difference; and

The analyzing unit can perform multivariate analysis using distribution information of the at least two circuit constants in the plurality of normal batteries.

＜6＞

The electronic device according to <1>,

The battery is a battery pack composed of a plurality of single cells.

The voltage measuring unit is capable of measuring the voltages of the plurality of cells included in the battery pack.

The voltage difference deriving unit may derive the difference value for each of the single cells.

＜7＞

The electronic device according to <6>, comprising:

a current measuring unit capable of measuring currents of the plurality of battery cells;

a calculation unit capable of calculating at least two circuit constants in an equivalent circuit of the single cell for each of the single cells using a current value obtained by the current measurement unit before the current is step-changed by the current supply unit and at least two of the first difference, the second difference, and the third difference; and

The analysis unit can perform multivariate analysis using distribution information of the at least two circuit constants in the plurality of cells or distribution information of the at least two circuit constants in the plurality of normal cells.

＜8＞

The electronic device according to any one of <1> to <7>,

The multivariate analysis method is the Markov-Taguchi method.

＜9＞

The electronic device according to any one of <1> to <7>,

The multivariate analysis method is a single-class support vector machine method.

＜10＞

A determination method comprising:

Supplying a step-changing current to the battery;

measuring the voltage of the battery;

deriving a difference between a first voltage and a second voltage based on the voltage value obtained by the measurement, the first voltage being the voltage value before the current flowing to the battery is changed in a step-like manner, and the second voltage being the voltage value after the current flowing to the battery is changed in a step-like manner; and

When deriving the difference, at least two of the following three differences are derived:

a first difference between the first voltage value and a third voltage value, the third voltage value being a voltage value after a component change of the second voltage value caused by a body resistance of the battery;

a second difference between the first voltage value and a fourth voltage value, the fourth voltage value being a voltage value after a component change of the second voltage value caused by a charge transfer resistance of the battery; and

A third difference between the first voltage value and a fifth voltage value, the fifth voltage value being a voltage value after a component change of the second voltage value caused by a diffusion resistance of the battery.

＜11＞

According to the determination method described in <10>,

The first difference value is derived from a voltage value in a period of 1 μs or more and less than 1 ms after the current is changed stepwise as the third voltage value.

＜12＞

According to the determination method described in <10>,

The method includes deriving the second difference value from a voltage value within a period of 1 ms or more and less than 10 s after the current is changed in a step-like manner as the fourth voltage value.

＜13＞

According to the determination method described in <10>,

The third difference value is derived by using a voltage value in a period of 10 seconds or more and less than 10000 seconds after the current is changed in a step-like manner as the fifth voltage value.

＜14＞

The measuring method according to any one of <10> to <13>,

The battery is a single cell,

The assay method includes:

measuring the current of the battery;

calculating at least two circuit constants in an equivalent circuit of the battery using a current value before the current is step-changed among the current values obtained by measurement and at least two of the first difference, the second difference, and the third difference; and

Multivariate analysis is performed using distribution information of the at least two circuit constants in a plurality of normal batteries.

＜15＞

The measuring method according to any one of <10> to <13>,

The battery is a battery pack composed of a plurality of single cells.

The determination method comprises:

measuring voltages of the plurality of cells included in the battery pack; and

The difference is derived for each of the single cells.

＜16＞

The determination method according to <15>, comprising:

measuring the current of the plurality of cells;

calculating at least two circuit constants in an equivalent circuit of the cell for each of the cells using a current value obtained by measurement before the current is changed in a stepwise manner and at least two of the first difference, the second difference, and the third difference; and

Multivariate analysis is performed using distribution information of the at least two circuit constants in the plurality of single cells or distribution information of the at least two circuit constants in the plurality of normal cells.

＜17＞

The measuring method according to any one of <10> to <16>,

The multivariate analysis method is the Markov-Taguchi method.

＜18＞

The measuring method according to any one of <10> to <16>,

The multivariate analysis method is a single-class support vector machine method.

The voltage difference derivation unit 14, the circuit constant calculation unit 15, and the multivariable analysis unit 16 can be implemented by at least one processor (e.g., a central processing unit (CPU)), at least one application-specific integrated circuit (ASIC), and/or at least one field programmable gate array (FPGA) and other circuits including at least one semiconductor integrated circuit. At least one processor can be configured to execute all or part of the various functions in the voltage difference derivation unit 14, the circuit constant calculation unit 15, and the multivariable analysis unit 16 by reading instructions from at least one non-temporary and tangible computer-readable medium. Such a medium can take various forms including various magnetic media such as hard disks, various optical media such as CDs or DVDs, and various semiconductor memories (i.e., semiconductor circuits) such as volatile memories or non-volatile memories, but is not limited thereto. Volatile memories may include DRAM and SRAM. Non-volatile memories may include ROM and NVRAM. ASIC is an integrated circuit (IC) specifically used to execute all or part of the various functions in the voltage difference derivation unit 14, the circuit constant calculation unit 15, and the multivariable analysis unit 16. The FPGA is an integrated circuit designed to be configurable after manufacture in order to execute all or part of the various functions in the voltage difference derivation unit 14 , the circuit constant calculation unit 15 , and the multivariate analysis unit 16 .

Claims (18)

1. An electronic device comprising: A current supply unit capable of supplying a step-wise changing current to the battery; a voltage measuring unit capable of measuring the voltage of the battery; and a voltage difference deriving unit capable of deriving a difference between a first voltage value and a second voltage value based on a voltage value measured by the voltage measuring unit, wherein the first voltage value is the voltage value before the current is changed stepwise by the current supply unit, and the second voltage value is the voltage value after the current is changed stepwise by the current supply unit. The voltage difference deriving unit is capable of deriving at least two of the following three difference values: a first difference between the first voltage value and a third voltage value, the third voltage value being a voltage value after a component change of the second voltage value caused by a body resistance of the battery; a second difference between the first voltage value and a fourth voltage value, the fourth voltage value being a voltage value after a component change of the second voltage value caused by a charge transfer resistance of the battery; and A third difference between the first voltage value and a fifth voltage value, the fifth voltage value being a voltage value after a component change of the second voltage value caused by a diffusion resistance of the battery. 2. The electronic device according to claim 1, The voltage difference deriving unit can derive the first difference value by using a voltage value in a period of 1 μs or more and less than 1 ms after the current supplier changes the current in a step-like manner as the third voltage value. 3. The electronic device according to claim 1, The voltage difference deriving unit can derive the second difference value by using, as the fourth voltage value, a voltage value within a period of 1 ms or longer and less than 10 s after the current supplier changes the current in a step-like manner. 4. The electronic device according to claim 1, The voltage difference deriving unit can derive the third difference value by using, as the fifth voltage value, a voltage value within a period of 10 seconds or more and less than 10000 seconds after the current supplier changes the current in a step-like manner. 5. The electronic device according to claim 1, The battery is a single cell, The electronic device comprises: a current measuring unit capable of measuring the current of the battery; a calculation unit capable of calculating at least two circuit constants in an equivalent circuit of the battery using a current value obtained by the current measurement unit before the current is step-changed by the current supply unit, and at least two of the first difference, the second difference, and the third difference; and The analyzing unit can perform multivariate analysis using distribution information of the at least two circuit constants in the plurality of normal batteries. 6. The electronic device according to claim 1, The battery is a battery pack composed of a plurality of single cells. The voltage measuring unit is capable of measuring the voltages of the plurality of cells included in the battery pack. The voltage difference deriving unit may derive the difference value for each of the single cells. 7. The electronic device according to claim 6, comprising: a current measuring unit capable of measuring currents of the plurality of battery cells; a calculation unit capable of calculating at least two circuit constants in an equivalent circuit of the single cell for each of the single cells using a current value obtained by the current measurement unit before the current is step-changed by the current supply unit and at least two of the first difference, the second difference, and the third difference; and The analyzing unit can perform multivariate analysis using distribution information of the at least two circuit constants in the plurality of cells or distribution information of the at least two circuit constants in the plurality of normal cells. 8. The electronic device according to any one of claims 1 to 7, The multivariate analysis method is the Markov-Taguchi method. 9. The electronic device according to any one of claims 1 to 7, The multivariate analysis method is a single-class support vector machine method. 10. A determination method, comprising: Supplying a step-changing current to the battery; measuring the voltage of the battery; deriving a difference between a first voltage and a second voltage based on the voltage value obtained by the measurement, the first voltage being the voltage value before the current flowing to the battery is changed in a step-like manner, and the second voltage being the voltage value after the current flowing to the battery is changed in a step-like manner; and When deriving the difference, at least two of the following three differences are derived: a first difference between the first voltage value and a third voltage value, the third voltage value being a voltage value after a component change of the second voltage value caused by a body resistance of the battery; a second difference between the first voltage value and a fourth voltage value, the fourth voltage value being a voltage value after a component change of the second voltage value caused by a charge transfer resistance of the battery; and A third difference between the first voltage value and a fifth voltage value, the fifth voltage value being a voltage value after a component change of the second voltage value caused by a diffusion resistance of the battery. 11. The measuring method according to claim 10, The first difference value is derived from a voltage value in a period of 1 μs or more and less than 1 ms after the current is changed stepwise as the third voltage value. 12. The assay method according to claim 10, The method includes deriving the second difference value from a voltage value within a period of 1 ms or more and less than 10 s after the current is changed in a step-like manner as the fourth voltage value. 13. The measuring method according to claim 10, The third difference value is derived by using a voltage value in a period of 10 seconds or more and less than 10000 seconds after the current is changed in a step-like manner as the fifth voltage value. 14. The assay method according to any one of claims 10 to 13, The battery is a single cell, The assay method includes: measuring the current of the battery; calculating at least two circuit constants in an equivalent circuit of the battery using a current value before the current is step-changed among the current values obtained by measurement and at least two of the first difference, the second difference, and the third difference; and Multivariate analysis is performed using distribution information of the at least two circuit constants in a plurality of normal batteries. 15. The assay method according to any one of claims 10 to 13, The battery is a battery pack composed of a plurality of single cells. The determination method comprises: measuring voltages of the plurality of cells included in the battery pack; and The difference is derived for each of the single cells. 16. The assay method according to claim 15, comprising: measuring the current of the plurality of cells; calculating at least two circuit constants in an equivalent circuit of the cell for each of the cells using a current value obtained by measurement before the current is changed in a stepwise manner and at least two of the first difference, the second difference, and the third difference; and Multivariate analysis is performed using distribution information of the at least two circuit constants in the plurality of single cells or distribution information of the at least two circuit constants in the plurality of normal cells. 17. The assay method according to any one of claims 10 to 16, The multivariate analysis method is the Markov-Taguchi method. 18 . The measuring method according to claim 10 , wherein the multivariate analysis method is a one-class support vector machine method.