Method for measuring impedance parameters, and apparatus for measuring impedance parameters

Abstract

An impedance parameter measurement method according to an embodiment of the present technology is a method for measuring an impedance parameter of an electrochemical device in which an electric circuit including a CPE serves as an equivalent circuit, and includes the following: (A) applying step-like current changes to the electrochemical device; (B) measuring the voltage of the electrochemical device at a plurality of different timings while the voltage of the electrochemical device is exhibiting a transient response to the application of current changes to the electrochemical device; and (C) deriving a p-constant for the CPE on the basis of the plurality of voltage values obtained from the measurement and deriving a T-constant for the CPE on the basis of the derived p-constant and the plurality of voltage values obtained from the measurement.

Description

[Technical Field]

[0001] This technology relates to an impedance parameter measurement method and an impedance parameter measurement apparatus. [Background technology]

[0002] In recent years, with the spread of electric and hybrid vehicles, and with the proliferation of power generation devices such as solar and wind power, which have unstable power generation sources and require power leveling, the demand for lithium-ion secondary batteries has been rapidly increasing.

[0003] In battery modules composed of numerous lithium-ion batteries, the inclusion of abnormal lithium-ion batteries can lead to reduced safety. One known degradation mode of lithium-ion batteries involves a significant change in the electrical double-layer capacity. By focusing on these differences in electrical double-layer capacity, it becomes possible to detect abnormal lithium-ion batteries that degrade using this mode.

[0004] The electric double-layer capacitance of a lithium-ion battery is sometimes described as an electrical circuit including a CPE (Constant Phase Element). A CPE is an element with two constants: a p-constant representing the element's characteristics and a T-constant representing its physical properties. Methods for solving these p-constants and T-constants in the time domain are disclosed, for example, in Patent Document 1 and Non-Patent Document 1. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2011-145944 [Non-patent literature]

[0006] [Non-Patent Document 1] Chun-Sing Cheng, Henry Shu-Hung Chung, Ricky Wing-Hong Lau, and Kelvin Yi-Wen Hong, "Time-Domain Modeling of Constant Phase Elements for Simulation of Lithium Battery Behavior," IEEE Transactions on Power Electronics 34(8), 2019, pp 7573-7587. [Overview of the Initiative]

[0007] However, both Patent Document 1 and Non-Patent Document 1 mentioned above had the problem of requiring a lot of computation time when calculating the time-domain behavior of an electrical circuit including a CPE. It is desirable to provide an impedance parameter measurement method and an impedance parameter measurement device that can measure the p constant and T constant while shortening the computation time.

[0008] The impedance parameter measurement method relating to the first aspect of this technology is a method for measuring the impedance parameters of an electrochemical device whose equivalent circuit is an electrical circuit including a CPE (Constant Phase Element), and includes the following three elements. (A) Applying a step-like current change to an electrochemical device (B) While the voltage of the electrochemical device is undergoing a transient response due to a change in current applied to the electrochemical device, the voltage of the electrochemical device is measured at multiple different timings. (C) Derive the p constant of the CPE based on multiple voltage values ​​obtained by measurement, and derive the T constant of the CPE based on the derived p constant and multiple voltage values ​​obtained by measurement.

[0009] The impedance parameter measuring device relating to the second aspect of this technology is a device capable of measuring the impedance parameters of an electrochemical device whose equivalent circuit is an electrical circuit including a CPE. This impedance parameter measuring device comprises a current source, a measurement circuit, and a signal processing unit. The current source is capable of applying a step-like current change to the electrochemical device. The measurement circuit is capable of measuring the voltage of the electrochemical device at multiple different timings while the voltage of the electrochemical device is in a transient response due to the current change applied to the electrochemical device. The signal processing unit is capable of deriving the p constant of the CPE based on the multiple voltage values ​​obtained by measurement, and also of deriving the T constant of the CPE based on the derived p constant and the multiple voltage values ​​obtained by measurement.

[0010] In the impedance parameter measurement method relating to the first aspect of this technology, and the impedance parameter measurement apparatus relating to the second aspect of this technology, a step-like current change is applied to an electrochemical device whose equivalent circuit is an electrical circuit including a CPE. While the voltage of the electrochemical device is undergoing a transient response, the voltage of the electrochemical device is measured at multiple different timings. Based on the multiple voltage values ​​obtained from the measurements, the p-constant of the CPE is derived, and based on the derived p-constant and the multiple voltage values ​​obtained from the measurements, the T-constant of the CPE is derived. This makes it possible to measure the p-constant and T-constant while reducing the calculation time.

[0011] Furthermore, the effects of this technology are not necessarily limited to those described herein, but may include any of the series of effects related to this technology described later. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 shows an example of an equivalent circuit of an electrochemical device. [Figure 2] Figure 2 shows an example of the voltage response equation for the equivalent circuit in Figure 1. [Figure 3]FIG. 3 is a diagram showing an example of the voltage response of an equivalent circuit derived from the voltage response equation of FIG. 2 in both linear scales. [Figure 4] FIG. 4 is a diagram showing an example of the voltage response of an equivalent circuit derived from the voltage response equation of FIG. 2 in both logarithmic scales. [Figure 5] FIG. 3 is a diagram showing an example of the voltage response of an equivalent circuit derived from the voltage response equation of FIG. 2 in both linear scales. [Figure 6] FIG. 4 is a diagram showing an example of the voltage response of an equivalent circuit derived from the voltage response equation of FIG. 2 in both logarithmic scales. [Figure 7] FIG. 7 is a diagram showing a schematic configuration example of a charge-discharge device according to a first embodiment of the present technology. [Figure 8] FIG. 8 is a diagram showing an example of the operation of the charge-discharge device of FIG. 7. [Figure 9] FIG. 9 is a diagram showing a schematic configuration example of an impedance parameter measurement system including a server device according to a second embodiment of the present technology. [Figure 10] FIG. 10 is a diagram showing an example in which the functions of the temporary storage unit, gradient calculation unit, and Z parameter calculation unit in FIGS. 7 and 9 are executed by a control unit. MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, embodiments for carrying out the present technology will be described in detail with reference to the drawings. The order of description is as follows. 1. Background 2. Measurement principle 3. First embodiment 4. Second embodiment 5. Modification example

[0014] <1. Background> In battery modules composed of numerous lithium-ion batteries, the inclusion of abnormal lithium-ion batteries can lead to reduced safety. One known degradation mode of lithium-ion batteries involves a significant change in the electrical double-layer capacity. By focusing on these differences in electrical double-layer capacity, it becomes possible to detect abnormal lithium-ion batteries that degrade using this mode.

[0015] The electric double-layer capacitance of a lithium-ion battery is sometimes described as an electrical circuit including a CPE (Constant Phase Element). A CPE is an element with two constants: a p constant representing the element's characteristics and a T constant representing its physical properties, and its impedance Z in the frequency domain. CPE It is described by the following formula, where j is the imaginary unit and ω is the angular frequency. Z CPE = 1 / {T × (jω)} p}

[0016] Measuring the p-constant and t-constant is useful for distinguishing between abnormal lithium-ion batteries that degrade in the above-mentioned degradation modes and normal lithium-ion batteries. Typically, the AC impedance method is used to measure the p-constant and t-constant. Measurement using the AC impedance method requires specialized equipment or circuits such as an FRA (Frequency Response Analyzer). Therefore, it has been difficult from a cost perspective to incorporate such specialized equipment or circuits into electronic devices equipped with battery modules or chargers for charging battery modules.

[0017] The following patent documents disclose methods for deriving time-domain solutions to electrical circuits including CPEs using non-integer order derivatives (fractional order derivatives), rather than integer order derivatives such as first or second order derivatives. Furthermore, the following non-patent documents disclose methods for deriving time-domain solutions to electrical circuits including CPEs using Laplace transforms.

[0018] • Patent document: JP 2011-145944 ·Non-patent literature: Chun-Sing Cheng, Henry Shu-Hung Chung, Ricky Wing-Hong Lau, and Kelvin Yi-Wen Hong, "Time-Domain Modeling of Constant Phase Elements for Simulation of Lithium Battery Behavior," IEEE Transactions on Power Electronics 34(8), 2019, pp 7573-7587.

[0019] However, both the above-mentioned patent documents and non-patent documents had the problem that calculating the time-domain behavior of electrical circuits including CPE required a lot of computation time. Focusing on this problem, the inventors of the present application propose below an impedance parameter measurement method and an impedance parameter measurement device that can measure the p constant and T constant while shortening the computation time.

[0020] <2. Measurement Principle> Figure 1 shows the equivalent circuit of an electrochemical device ED. As shown in Figure 1, the electrochemical device ED is represented by an equivalent circuit including a parallel circuit of a CPE and a resistor (R). The electrochemical device ED is, for example, a lithium-ion battery (secondary battery), a dye-sensitized solar cell (solar cell), or a fuel cell (electrochemical cell). A current source IS is connected to the electrochemical device ED, and the current I generated by the current source IS is supplied to the electrochemical device ED. If the electrochemical device ED is a lithium-ion battery (secondary battery), the current I generated by the current source IS is supplied to the electrochemical device ED when the electrochemical device ED is fully charged.

[0021] The current source IS is capable of applying a step-like current change to the electrochemical device ED. For example, the current source IS can apply a rising-wave current change to the electrochemical device ED as a step-like current change. For example, the current source IS can apply a falling-wave current change to the electrochemical device ED as a step-like current change.

[0022] When an electrochemical device ED is supplied with a step-like current change from a current source IS, a transient response occurs in the voltage of the electrochemical device ED. This transient response lasts for several tens of microseconds and then converges to a constant value. Suppose that the voltage of the electrochemical device ED is measured at multiple (at least two) different timings during the several tens of microseconds in which the voltage of the electrochemical device ED is in a transient response. If a log-log graph of time and voltage is plotted using these multiple voltage values, a linear graph with a slope α is obtained.

[0023] Here, the voltage across the CPE in an electrical circuit including a parallel circuit of the CPE and a resistor (R) can be expressed, for example, by the voltage response equation shown in Figure 2 (CSChenge et al., IEEE Trans. on Power Elec. 34(8), 2019, 7573-7587). The voltage ν of the CPE obtained by this equation is CPE Using time-voltage ν CPE When both linear graphs are plotted, a curve graph like the one shown in Figure 3 is obtained. Figure 3 shows examples of graphs when the p constant is fixed at 0.8 and the T constant is 0.1, 0.3, 0.5, 0.7, and 0.9. Furthermore, the voltage ν of the CPE obtained by the above equation is... CPE Using time-voltage ν CPE When a log-log graph of this is plotted, a curve like the one shown in Figure 4 is obtained. Figure 4 shows examples of graphs when the p constant is fixed at 0.8 and the T constant is 0.1, 0.3, 0.5, 0.7, and 0.9. In Figure 4, the voltage ν of the CPE is CPE In the period just before the graphs converge to a certain value, we can see that the slopes of each graph are roughly equal.

[0024] Also, using the voltage ν of the CPE obtained by the above formula, CPE when drawing the two linear graphs of time and voltage ν CPE a graph of a curve as shown in, for example, FIG. 5 is obtained. In FIG. 5, the T constant is fixed at 0.9Fs p-1 and graphs when the p constants are 0.5, 0.6, 0.7, 0.8, and 0.9 are illustrated. Further, using the voltage ν of the CPE obtained by the above formula, CPE when drawing the two logarithmic graphs of time and voltage ν CPE a graph of a curve as shown in, for example, FIG. 6 is obtained. In FIG. 6, the T constant is fixed at 0.9Fs p-1 and graphs when the p constants are 0.5, 0.6, 0.7, 0.8, and 0.9 are illustrated. In FIG. 6, it can be seen that the slopes of the respective graphs are different from each other in the period before the voltage ν of the CPE CPE converges to a constant value.

[0025] Note that the slope α obtained when a step-like current change is given to the electrochemical device ED is equal to the p constant when the resistance R connected in parallel is considered to be sufficiently large or when the time change of the voltage ν CPE is considered to be sufficiently small. This can be explained by the following formula.

[0026] According to the above non-patent literature, the voltage transient response of a circuit in which a CPE and an R belong to a parallel cell can be described by Equation (1). n is the number of steps, T is the step time, C is the T constant of the CPE, Φ is the p constant of the CPE, and i is the current.

Equation

[0027] Here, in the case of a step response, the current i is a constant, and assuming that the voltage ν CPE inside the sigma symbol is a constant voltage ν CONST or assuming that R is sufficiently large and ν CPE / R is considered to be zero. In this case, i and νCONST Terms containing can be taken outside the sigma symbol. In this case, equation (1) can be transformed into equation (2).

number

[0028] Here, using the relation in equation (3), equation (2) can be transformed into equation (4).

number

number

[0029] Here, if we change the symbols from nT to t (elapsed time), C to T, and Φ to p, equation (4) becomes equation (5). Furthermore, taking the logarithm of both sides of equation (5), we get equation (6). Equation (6) is the equation of a straight line. p is the slope of the log-log plot, and the second term on the right side is the intercept.

[0030]

number

number

[0031] From the above, it can be seen that the p constant can be determined from the magnitude of the slope α obtained when a step-like current change is applied to the electrochemical device ED. Below, we will describe an apparatus that can derive the p constant using the slope α obtained when a step-like current change is applied to the electrochemical device ED, and then derive the T constant using the derived p constant. In the following, we will use a lithium-ion battery as an example of the electrochemical device ED, but the electrochemical device ED is not limited to a lithium-ion battery and may be other devices.

[0032] <3. First Embodiment> [composition] The configuration of the charge / discharge device 200 according to the first embodiment of this technology will now be described. Figure 7 shows a schematic example of the configuration of the charge / discharge device 200. The charge / discharge device 200 is a device for charging and discharging the secondary battery 100. The charge / discharge device 200 corresponds to a specific example of the "impedance parameter measuring device" according to one embodiment of this technology.

[0033] The charge / discharge device 200 not only has the function of charging and discharging the secondary battery 100, but also has the function of measuring the impedance parameters of the secondary battery 100. The "impedance parameters of the secondary battery 100" refer to the p constant and T constant of the equivalent circuit when the equivalent circuit of the secondary battery 100 can be represented by an electrical circuit that includes a parallel circuit of CPE and a resistor (R).

[0034] The secondary battery 100 is a lithium-ion secondary battery. The lithium-ion secondary batteries contained in the secondary battery 100 may be individual cells, battery blocks in which multiple unit cells are connected, or battery packs in which battery blocks and accessories are packaged together. In a battery pack, multiple lithium-ion secondary batteries are connected in series. Within a battery pack, multiple lithium-ion secondary batteries connected in parallel may be included.

[0035] The charge / discharge device 200 includes, for example, a charge / discharge circuit 210, a charge / discharge control unit 220, an IV measurement circuit 230, a temporary storage unit 240, a gradient calculation unit 250, a storage unit 260, a Z parameter calculation unit 270, and an output unit 280, as shown in Figure 7.

[0036] The charge / discharge circuit 210 includes a charging circuit for charging the secondary battery 100 and a discharge circuit for discharging the secondary battery 100. The charging circuit includes, for example, a generator and a converter. The charge / discharge control unit 220 is capable of controlling the current for charging the secondary battery 100 and controlling the current for discharging the secondary battery 100. The charge / discharge control unit 220 is composed of, for example, an MPU (Micro-Processing Unit) that performs charge / discharge control, or a CPU (Central Processing Unit) on which a charge / discharge control program is loaded. The charge / discharge control unit 220 is capable of controlling the charge / discharge circuit 210 to provide a step-like current change to the secondary battery 100. For example, the charge / discharge control unit 220 is capable of controlling the charge / discharge circuit 210 to provide a rising-wave current change to the secondary battery 100 as a step-like current change. For example, the charge / discharge control unit 220 is capable of controlling the charge / discharge circuit 210 to provide a falling-wave current change to the secondary battery 100 as a step-like current change.

[0037] The charge / discharge circuit 210 can provide a step-like current change to the secondary battery 100 through control by the charge / discharge control unit 220. For example, the charge / discharge circuit 210 can provide a rising-wave current change to the secondary battery 100 as a step-like current change through control by the charge / discharge control unit 220. For example, the charge / discharge circuit 210 can provide a falling-wave current change to the secondary battery 100 as a step-like current change through control by the charge / discharge control unit 220.

[0038] The IV measurement circuit 230 includes a measurement circuit capable of measuring the current and voltage of the secondary battery 100. The IV measurement circuit 230 can measure the current and voltage while a transient response occurs in the voltage of the secondary battery 100, for example, when a step-like current change is applied to the secondary battery 100. Here, this transient response continues for about several tens of microseconds and then converges to a constant value. The IV measurement circuit 230 can measure the voltage of the secondary battery 100 at multiple (at least two) different timings during the several tens of microseconds during which the voltage of the secondary battery 100 is in a transient response. In other words, the period during which the voltage of the secondary battery 100 is measured at multiple (at least two) different timings in the IV measurement circuit 230 is a period of several tens of microseconds or less after a step-like current change is applied to the secondary battery 100.

[0039] The gradient calculation unit 250 is capable of deriving the slope α on a time-voltage log-log graph based on multiple voltage values ​​obtained by measurements performed by the IV measurement circuit 230. The gradient calculation unit 250 is composed of, for example, a CPU on which a program for deriving the slope α is loaded.

[0040] The memory unit 260 is composed of, for example, volatile memory such as DRAM (Dynamic Random Access Memory), or non-volatile memory such as EEPROM (Electrically Erasable Programmable Read-Only Memory) or flash memory. The memory unit 260 stores, for example, gradient reference values ​​261. The gradient reference values ​​261 include a table in which slopes and p-constants are linked to each other. This table includes multiple slopes of different magnitudes and multiple p-constants, one for each slope.

[0041] The Z-parameter calculation unit 270 is capable of deriving the p-constant of the CPE of the equivalent circuit of the secondary battery 100 based on the slope α obtained by the slope calculation unit 250. The Z-parameter calculation unit 270 can read the p-constant corresponding to the slope α obtained by the slope calculation unit 250 from the slope reference value 261 of the storage unit 260, and use the read-out p-constant as the p-constant of the CPE of the equivalent circuit of the secondary battery 100.

[0042] The Z-parameter calculation unit 270 is capable of deriving the T-constant of the CPE of the equivalent circuit of the secondary battery 100 based on the derived p-constant and multiple voltage values ​​obtained by measurement at the IV measurement circuit 230. The Z-parameter calculation unit 270 can derive the T-constant, for example, using the following equation (see the above non-patent document). Here, ΔI is the change in current before and after the current step, ΔV is the change in voltage after the current step, Δt is the elapsed time after the current step, and Γ is the Γ function. T = (ΔI / ΔV) × {Δt} p / Γ(p+1)}

[0043] The output unit 280 is an output interface that outputs the impedance parameters (p constant, T constant) obtained by the Z parameter calculation unit 270 to the outside.

[0044] Next, we will explain how to measure the impedance parameters of the secondary battery 100 in the charge / discharge device 200.

[0045] Figure 8 shows an example of the procedure for measuring the impedance parameters of the secondary battery 100 in the charge / discharge device 200. First, the charge / discharge circuit 210 applies a step-like current change to the secondary battery 100 (step S101). Next, the IV measurement circuit 230 applies a step-like current change to the secondary battery 100 and measures the voltage at multiple different timings while the voltage of the secondary battery 100 is in a transient response (step S102).

[0046] Next, the gradient calculation unit 250 derives the slope α on a time-voltage log-log graph based on multiple voltage values ​​obtained by the IV measurement circuit 230. Subsequently, the Z parameter calculation unit 270 derives the p constant of the CPE of the equivalent circuit of the secondary battery 100 based on the slope α obtained by the gradient calculation unit 250 (step S103). The Z parameter calculation unit 270 further derives the T constant of the CPE of the equivalent circuit of the secondary battery 100 based on the derived p constant and multiple voltage values ​​obtained by the IV measurement circuit 230 (step S104). The output unit 280 outputs the impedance parameters (p constant, T constant) obtained by the Z parameter calculation unit 270 to the outside (step S105). In this way, the impedance parameters of the secondary battery 100 in the charge / discharge device 200 are measured.

[0047] [effect] Next, we will explain the effects of the charge / discharge device 200.

[0048] In this embodiment, a step-like current change is applied to a secondary battery 100 whose equivalent circuit includes an electrical circuit containing a CPE. While the voltage of the secondary battery 100 is undergoing a transient response, the voltage of the secondary battery 100 is measured at multiple different timings. Based on the multiple voltage values ​​obtained from the measurements, the p-constant of the CPE is derived, and based on the derived p-constant and the multiple voltage values ​​obtained from the measurements, the T-constant of the CPE is derived. This allows for the measurement of the p-constant and T-constant while reducing calculation time.

[0049] In this embodiment, the p-constant of CPE is derived based on the slope α of a time-voltage log-log graph obtained from multiple voltage values ​​obtained through measurement. This allows for the measurement of the p-constant and T-constant in a short time while reducing calculation time.

[0050] In this embodiment, the period for measuring multiple voltage values ​​is less than tens of microseconds after a current change is applied to the secondary battery 100. Thus, in this embodiment, the p constant and T constant are derived based on the transient response over a very short period. Therefore, the p constant and T constant can be measured in a short time while reducing the calculation time.

[0051] In this embodiment, a rising-wave current change is applied to the secondary battery 100 as a step-like current change. This allows the p-constant and T-constant to be measured in a short time while reducing the calculation time.

[0052] In this embodiment, a falling-wavelength current change is applied to the secondary battery 100 as a step-like current change. This allows the p-constant and T-constant to be measured in a short time while reducing the calculation time.

[0053] <4. Second Embodiment> Next, an impedance parameter measurement system equipped with a server device 400 as an impedance parameter measurement device according to a second embodiment of this technology will be described. Figure 9 shows a schematic example of the impedance parameter measurement system according to this embodiment.

[0054] The impedance parameter measurement system comprises a secondary battery 100, a charge / discharge device 300, and a server device 400. The charge / discharge device 300 and the server device 400 are connected via a communication network 500. The charge / discharge device 300 and the server device 400 are able to communicate with each other via the communication network 500. The communication network 500 includes, for example, the internet, a cloud network, or a carrier-specific network.

[0055] The charge / discharge device 300 is a device for charging and discharging the secondary battery 100 and is a network communication type device that has the function of communicating with an external device. The charge / discharge device 300 includes, for example, a charge / discharge circuit 210, a charge / discharge control unit 220, an IV measurement circuit 230, a communication unit 310, and an output unit 280, as shown in Figure 9. The charge / discharge circuit 210 corresponds to the charge / discharge circuit 210 according to the above embodiment. The charge / discharge control unit 220 corresponds to the charge / discharge control unit 220 according to the above embodiment. The IV measurement circuit 230 corresponds to the IV measurement circuit 230 according to the above embodiment. The communication unit 310 is a communication interface that can communicate with the server device 400 via the communication network 500. The communication unit 310 is capable of outputting impedance parameters transmitted from the server device 400 to the output unit 280.

[0056] The server device 400 includes, for example, a temporary storage unit 240, a gradient calculation unit 250, a storage unit 260, a Z-parameter calculation unit 270, and a communication unit 410, as shown in Figure 9. The temporary storage unit 240 corresponds to the temporary storage unit 240 according to the above embodiment. The gradient calculation unit 250 corresponds to the gradient calculation unit 250 according to the above embodiment. The Z-parameter calculation unit 270 corresponds to the Z-parameter calculation unit 270 according to the above embodiment. The communication unit 410 is a communication interface capable of communicating with the charge / discharge device 300 via the communication network 500. The communication unit 410 is capable of transmitting impedance parameters obtained by the Z-parameter calculation unit 270 to the charge / discharge device 300.

[0057] In this embodiment, the functions of the temporary storage unit 240, the gradient calculation unit 250, the storage unit 260, and the Z-parameter calculation unit 270 are provided in the server device 400. Even in this case, the p-constant and T-constant can be measured while shortening the calculation time, similar to the above embodiment.

[0058] <5. Variation> In each of the above embodiments, for example, as shown in Figure 10, the functions of the temporary storage unit 240, the gradient calculation unit 250, and the Z-parameter calculation unit 270 may be implemented by the control unit 320. In this case, the control unit 320 is composed of, for example, an MPU capable of executing the functions of the temporary storage unit 240, the gradient calculation unit 250, and the Z-parameter calculation unit 270, or a CPU into which a program 262 describing a series of operations of the temporary storage unit 240, the gradient calculation unit 250, and the Z-parameter calculation unit 270 is loaded. The program 262 is stored, for example, in the storage unit 260.

[0059] In the above embodiments and their variations, the object for which impedance parameters are to be determined was the secondary battery 100. However, in the above embodiments and their variations, the object for which impedance parameters are to be determined is not limited to the secondary battery 100, but may be other electrochemical devices.

[0060] Furthermore, this technology can also be configured as follows: <1> A method for measuring the impedance parameters of an electrochemical device whose equivalent circuit is an electrical circuit including a CPE (Constant Phase Element), Applying a step-like current change to the electrochemical device, By applying the current change to the electrochemical device, the voltage of the electrochemical device is measured at multiple different timings while the voltage of the electrochemical device is undergoing a transient response. The p-constant of the CPE is derived based on the multiple voltage values ​​obtained by the measurement, and the T-constant of the CPE is derived based on the derived p-constant and the multiple voltage values ​​obtained by the measurement. including Method for measuring impedance parameters. <2> The p-constant of CPE is derived based on the slope of the time-voltage log-log graph obtained from the multiple voltage values ​​obtained by the above measurement. including <1> The impedance parameter measurement method described above. <3> The measurement period is less than tens of microseconds after the current change is applied to the electrochemical device. <1> or <2> The impedance parameter measurement method described above. <4> To the electrochemical device, a rising-wave current change is applied as the step-shaped current change. including <1> or <3> An impedance parameter measurement method described in any one of the following. <5> To the electrochemical device, a current change with a falling-edge waveform is applied as the step-shaped current change. including <1> or <3> An impedance parameter measurement method described in any one of the following. <6> An impedance parameter measuring device for an electrochemical device whose equivalent circuit is an electrical circuit including a CPE (Constant Phase Element), A current source capable of applying a step-like current change to the electrochemical device, A measurement circuit capable of measuring the voltage of the electrochemical device at multiple different timings while the voltage of the electrochemical device is undergoing a transient response by applying the current change to the electrochemical device, A signal processing unit capable of deriving the p constant of the CPE based on a plurality of voltage values ​​obtained by the measurement, and deriving the T constant of the CPE based on the derived p constant and the plurality of voltage values ​​obtained by the measurement. Equipped with Impedance parameter measuring device.

[0061] The effects described herein are illustrative only, and therefore the effects of this technology are not limited to those described herein. Accordingly, other effects may be obtained with respect to this technology.

Claims

1. A method for measuring the impedance parameters of an electrochemical device whose equivalent circuit is an electrical circuit including a CPE (Constant Phase Element), Applying a step-like current change to the electrochemical device, By applying the current change to the electrochemical device, the voltage of the electrochemical device is measured at multiple different timings while the voltage of the electrochemical device is undergoing a transient response. The p-constant of the CPE is derived based on the multiple voltage values ​​obtained by the measurement, and the T-constant of the CPE is derived based on the derived p-constant and the multiple voltage values ​​obtained by the measurement. including Method for measuring impedance parameters.

2. The p-constant of the CPE is derived based on the slope of the time-voltage log-log graph obtained from the multiple voltage values ​​obtained by the above measurement. including The impedance parameter measurement method according to claim 1.

3. The measurement period is less than tens of microseconds after the current change is applied to the electrochemical device. The impedance parameter measurement method according to claim 1 or claim 2.

4. To the electrochemical device, a rising-wave current change is applied as the step-shaped current change. including The impedance parameter measurement method according to claim 1 or claim 2.

5. To the electrochemical device, a current change with a falling-edge waveform is applied as the step-shaped current change. including The impedance parameter measurement method according to claim 1 or claim 2.

6. An impedance parameter measuring device for an electrochemical device whose equivalent circuit is an electrical circuit including a CPE (Constant Phase Element), A current source capable of applying a step-like current change to the electrochemical device, A measurement circuit capable of measuring the voltage of the electrochemical device at multiple different timings while the voltage of the electrochemical device is undergoing a transient response by applying the current change to the electrochemical device, A signal processing unit capable of deriving the p constant of the CPE based on a plurality of voltage values ​​obtained by the measurement, and deriving the T constant of the CPE based on the derived p constant and the plurality of voltage values ​​obtained by the measurement. Equipped with Impedance parameter measuring device.

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