Methods for determining polarization impedance, the system for determining polarization impedance, and machine-readable storage media.

Abstract

This invention provides a method, system, and machine-readable storage medium for determining polarization impedance, belonging to the field of energy storage analysis. The method includes: determining a relaxation time distribution function with resistance-capacitance impedance and resistance-inductance impedance as variables based on the electrochemical AC impedance spectrum of the target energy storage device under a set excitation; further determining a fitted relaxation time distribution characteristic curve of the resistance-inductance impedance; and determining the impedance of each polarization inductance corresponding to each peak based on the number of peaks in the fitted relaxation time distribution characteristic curve and the area below the peak curve corresponding to each peak. This invention's method enables polarization characteristic analysis of the measured electrochemical AC impedance spectrum without preprocessing the energy storage device using an equivalent circuit model, effectively reducing data processing workload. Furthermore, this method expands the application scope of electrochemical AC impedance spectroscopy.

Description

Technical Field

[0001] This invention relates to the field of energy storage analysis, and more specifically to a method, system, and machine-readable storage medium for determining polarization impedance. Background Technology

[0002] The depletion of fossil fuels is considered one of the most pressing social problems facing humanity this century. The technology industry targeting renewable energy is flourishing globally, with advancements in electrochemical energy storage technology, particularly the significant performance improvements brought about by the iteration of lithium-ion battery technology, indirectly driving the development of energy science. However, electrochemical energy storage devices, including lithium-ion batteries, often encounter various problems in real-world operating environments, such as rapidly shortened cycle life at low temperatures or reduced usable capacity at high current rates.

[0003] Electrochemical impedance spectroscopy (EIS) is a widely used characterization technique for analyzing the internal kinetic processes of electrochemical systems. However, due to its complex principles, numerous interfering factors, and large data processing volume, it often leads to erroneous characterization results. The core issue lies in the preprocessing step of converting the system into an equivalent circuit model when interpreting EIS spectra. This preprocessing requires relevant personnel to construct the equivalent circuit model based on experience, which is easily influenced by subjective biases, resulting in an unreasonable model output.

[0004] Furthermore, when faced with complex high-order equivalent circuit models, conventional Nyquist plot fitting curves cannot reflect the polarization behavior with low impedance, making it difficult to quantify the extremely low impedance values ​​in electrochemical AC impedance spectra. Summary of the Invention

[0005] The purpose of this invention is to provide a method, system, and machine-readable storage medium for determining polarization impedance. By employing the method of this invention, polarization characteristic analysis can be performed on the measured electrochemical impedance spectroscopy without preprocessing the energy storage device using an equivalent circuit model, effectively reducing data processing workload. Furthermore, the method of this invention can expand the application scope of electrochemical impedance spectroscopy.

[0006] To achieve the above objectives, embodiments of the present invention first provide a method for determining polarization impedance. The method includes: determining a relaxation time distribution function with resistor-capacitor impedance and resistor-inductor impedance as variables based on the electrochemical AC impedance spectrum of the target energy storage device under a set excitation, wherein the resistor-capacitor impedance and the resistor-inductor impedance are related to the angular frequency of the set excitation; determining a fitted relaxation time distribution characteristic curve of the resistor-inductor impedance based on the relaxation time distribution function; determining the number of polarization inductor impedances in the resistor-inductor impedance based on the number of peaks in the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance; and determining the impedance of each polarization inductor impedance corresponding to each peak in the resistor-inductor impedance based on the number of polarization inductor impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance.

[0007] Optionally, the impedance of each polarized inductor impedance is determined by the following method: if the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance includes a single peak, the impedance of the polarized inductor impedance in the resistor-inductor impedance is determined as the integral value of the area below the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance; or if the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance includes multiple peaks, the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance is decomposed into multiple peak curves corresponding to the multiple peaks, and the impedance of each polarized inductor impedance in the resistor-inductor impedance is determined as the integral value of the area below the corresponding peak curve.

[0008] Optionally, the determining method further includes: determining the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance based on the relaxation time distribution function; determining the number of polarized capacitor impedances in the resistor-capacitor impedance based on the number of peaks in the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance; and determining the impedance of each polarized capacitor impedance corresponding to each peak in the resistor-capacitor impedance based on the number of polarized capacitor impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance.

[0009] Optionally, the impedance of each polarized capacitor impedance is determined by the following method: if the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance includes a single peak, the impedance of the polarized capacitor impedance in the resistor-capacitor impedance is determined as the integral value of the area below the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance; or if the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance includes multiple peaks, the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance is decomposed into multiple peak curves corresponding to the multiple peaks, and the impedance of each polarized capacitor impedance in the resistor-capacitor impedance is determined as the integral value of the area below the corresponding peak curve.

[0010] Optionally, the relaxation time distribution function is expressed by the following equation:

[0011]

[0012] Among them, h RC,k h is the characteristic value of the relaxation time distribution of the impedance of the Nth resistor-capacitor circuit. RL,k Let τ be the characteristic value of the relaxation time distribution of the impedance of the Nth resistor-inductor circuit. k For the Nth relaxation time, R Ω Let ω be the lumped resistance of the target energy storage device, C be the lumped capacitance of the target energy storage device, L be the lumped inductance of the target energy storage device, ω be the set excitation angular frequency, and j be a complex unit.

[0013] Optionally, the method for obtaining the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance includes: obtaining the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance using the Gaussian distribution method and the Tikhonov regularization method based on the relaxation time distribution function.

[0014] Optionally, the target energy storage device includes: a lithium-ion battery, an electric double-layer capacitor, or a flow battery.

[0015] On the other hand, embodiments of the present invention also provide a system for determining polarization impedance. The system includes: a target function determination device, used to determine a relaxation time distribution function with resistor-capacitor impedance and resistor-inductor impedance as variables based on the electrochemical AC impedance spectrum of a target energy storage device under a set excitation, wherein the resistor-capacitor impedance and the resistor-inductor impedance are related to the angular frequency of the set excitation; a first characteristic curve determination device, used to determine a fitted relaxation time distribution characteristic curve of the resistor-inductor impedance based on the relaxation time distribution function; a first number determination device, used to determine the number of polarization inductor impedances in the resistor-inductor impedance based on the number of peaks in the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance; and a first impedance determination device, used to determine the impedance of each polarization inductor impedance corresponding to each peak in the resistor-inductor impedance based on the number of polarization inductor impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance.

[0016] Optionally, the determining system further includes: a second characteristic curve determining device, used to determine the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance based on the relaxation time distribution function; a second number determining device, used to determine the number of polarized capacitor impedances in the resistor-capacitor impedance based on the number of peaks in the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance; and a second impedance determining device, used to determine the impedance of each polarized capacitor impedance corresponding to each peak in the resistor-capacitor impedance based on the number of polarized capacitor impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance.

[0017] On the other hand, embodiments of the present invention also provide a machine-readable storage medium storing instructions for causing a machine to perform the polarization impedance determination method described in any of the preceding claims.

[0018] Compared with the prior art, the present invention has the following advantages through the above technical solution:

[0019] (1) This invention can perform polarization characteristic analysis on the measured electrochemical impedance spectroscopy without preprocessing the equivalent circuit model of the energy storage device. The characteristic parameters of each polarization peak inside the energy storage device can be obtained in a single calculation, which can effectively reduce the workload of data processing. Furthermore, this invention identifies polarization behavior by recognizing peaks in the characteristic curve, which can distinguish various polarization behaviors in complex electrochemical systems and quantify extremely low impedance values ​​that are difficult to obtain in ordinary electrochemical impedance spectroscopy. Even those who are not familiar with Nyquist plots can intuitively understand the polarization characteristics inside the system.

[0020] (2) This invention innovatively incorporates inductive components into the relaxation time distribution function, and plots relaxation time distribution function curves including resistive and inductive components and resistive and capacitive components. This can fully extend the relaxation time distribution analysis method to other energy storage device characterization and testing fields, making the application range of electrochemical AC impedance spectroscopy wider.

[0021] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0023] Figure 1 This is a schematic flowchart of a method for determining polarization impedance according to an embodiment of this application;

[0024] Figure 2 This is a schematic diagram of the electrochemical AC impedance spectrum of a target energy storage device according to an embodiment of this application;

[0025] Figure 3 This is a schematic diagram of the equivalent circuit model of the target energy storage device according to an embodiment of this application;

[0026] Figure 4 This is a schematic diagram of the relaxation time distribution for resistive and inductive elements according to an embodiment of this application;

[0027] Figure 5 This is a schematic diagram of the relaxation time distribution for a resistive and capacitive element according to an embodiment of this application;

[0028] Figure 6 This is a schematic diagram of a polarization impedance determination system according to an embodiment of this application;

[0029] Figure 7 This is a schematic diagram of the internal structure of a computer device according to an embodiment of this application.

[0030] Explanation of reference numerals in the attached figures

[0031] Determining the 200-polarization impedance system;

[0032] 210 - Objective function determination device, 220 - First characteristic curve determination device, 230 - First number determination device, 240 - First impedance determination device, 250 - Second characteristic curve determination device, 260 - Second number determination device, 270 - Second impedance determination device.

[0033] A01 - Processor, A02 - Network interface, A03 - Internal memory, A04 - Display screen, A05 - Input device, A06 - Non-volatile storage medium;

[0034] B01 - Operating System, B02 - Computer Program. Detailed Implementation

[0035] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0036] This application first provides a method S100 for determining polarization impedance, such as... Figure 1 As shown, the determination method S100 may include steps S110-S140.

[0037] Step S110: Based on the electrochemical AC impedance spectrum of the target energy storage device under a set excitation, determine the relaxation time distribution function with resistance-capacitance impedance and resistance-inductance impedance as variables, wherein the resistance-capacitance impedance and resistance-inductance impedance are related to the angular frequency of the set excitation.

[0038] In one embodiment, the target energy storage device may include devices such as lithium-ion batteries, electric double-layer capacitors, or flow batteries. Therefore, the polarization impedance determination method of the present invention can be extended to fields other than lithium-ion batteries, such as electric double-layer capacitors and flow batteries.

[0039] In one embodiment, step S110 may include steps S111-S112.

[0040] Step S111: Obtain the electrochemical AC impedance spectrum of the target energy storage device under a set excitation.

[0041] In one embodiment, the electrochemical impedance spectroscopy (EIS) in step S111 can be obtained experimentally. Specifically, it is necessary to control the experimental conditions (temperature T and battery state of charge (SOC)) to measure the EIS of the system under test (i.e., the target energy storage device mentioned above, such as a lithium-ion battery). The measurement results are as follows: Figure 2 As shown. Then, data including frequency, real part of impedance, and imaginary part of impedance can be obtained from the electrochemical impedance spectroscopy. Specifically, when testing the electrochemical impedance spectroscopy of the system under test, a voltage or current of a specific frequency can be selected as the excitation source for the system.

[0042] In one embodiment, a system of equations including the real part Z' and the imaginary part Z” of the impedance can be obtained according to the following formula:

[0043] Z(ω)=X(ω) / J(ω),

[0044] Z(ω)=Z'(ω)+jZ””ω,

[0045] Where J(ω) is the AC excitation selected in the electrochemical impedance spectroscopy (EIS) test, X(ω) is the AC response selected in the EIS test, ω is the angular frequency of the excitation selected in the EIS test, Z(ω) is the AC impedance of the system under test, Z'(ω) is the real part of the electrochemical AC impedance of the system under test, Z'(ω) is the imaginary part of the electrochemical AC impedance of the system under test, and j is the complex unit.

[0046] Step S112: Establish the relaxation time distribution function of the electrochemical impedance spectroscopy.

[0047] In this invention, the relaxation time distribution function uses the resistance-capacitance and resistance-inductance impedances as variables. That is, compared to existing energy storage devices that primarily use capacitors, this invention adds inductive components, including both inductors and resistive-inductor elements. While capacitors can be used for characterizing lithium-ion batteries, the addition of inductive components enhances their application in electrochemical testing technologies, thereby expanding their practical application scope.

[0048] In one embodiment of step S111, the algebraic relationship between frequency and impedance has been given as follows:

[0049] Z(ω)=Z'(ω)+jZ””ω,

[0050] Where Z'(ω) is the real part of the impedance, Z'(ω) is the imaginary part of the impedance, and j is the complex unit.

[0051] In addition, the algebraic relationships between other components and impedance are as follows:

[0052] For resistance, Z = R;

[0053] For an inductor, Z = jωL;

[0054] For capacitors, Z = 1 / (jωC);

[0055] For a resistor and capacitor connected in parallel, Z = R / (1 + jωτ) RC );

[0056] For a resistor and inductor in parallel, Z = Rjωτ RL / (1+jωτ RL ).

[0057] In one embodiment, based on the algebraic relationship between the aforementioned components and impedance, the established relaxation time distribution function can be expressed by the following formula:

[0058]

[0059] Among them, h RC,k h is the characteristic value of the relaxation time distribution of the impedance of the Nth resistor-capacitor circuit. RL,k Let τ be the characteristic value of the relaxation time distribution of the impedance of the Nth resistor-inductor circuit. k For the Nth relaxation time, R Ω Let ω be the lumped resistance of the target energy storage device, C be the lumped capacitance of the target energy storage device, L be the lumped inductance of the target energy storage device, ω be the set excitation angular frequency, and j be a complex unit.

[0060] The physical meaning of the relaxation time distribution function is to characterize the internal dynamics of the electrochemical system, which is equivalent to constructing a system such as... Figure 3 The equivalent circuit model is shown. However, compared to the traditional method of constructing an equivalent circuit model, the method of this invention can reduce the workload of spectral analysis of electrochemical AC impedance spectroscopy, while also being able to separately demonstrate the resistance effect, capacitance effect, inductance effect, resistance-capacitance effect, and resistance-inductance effect, thereby expanding the scope of practical applications. For example, it can be extended to fields beyond lithium-ion batteries, such as double-layer capacitors and flow batteries.

[0061] Step S120: Determine the fitting relaxation time distribution characteristic curve of the resistor and inductor impedance based on the relaxation time distribution function.

[0062] In one embodiment, the relaxation time distribution function can be solved by using the Gaussian distribution method and the Tikhonov regularization method to obtain the fitted relaxation time distribution characteristic curve of the resistor and inductor impedance.

[0063] That is, based on the relaxation time distribution function established in one embodiment of step S112, the result matrix h of the relaxation time distribution of the resistance-capacitance circuit impedance of the system under test can be output respectively. RC,k The resulting matrix h is the relaxation time distribution of (τ) and the impedance of the resistive and inductive circuits. RL,k (ω).

[0064] Specifically, it can be expressed in log 10 τ k h is the x-axis. RC,k (ω k ) or h RL,k (τ k Using the ordinate as the vertical axis, plot the corresponding fitted relaxation time distribution characteristic curves for the resistor-capacitor impedance and the resistor-inductor impedance, respectively. The two characteristic curves obtained are shown below. Figure 4 and Figure 5 As shown.

[0065] The specific calculation process is as follows:

[0066] For hRC,k and h RL,k ,have:

[0067]

[0068]

[0069] Among them, for h RC,k and h RL,k The calculation of h is an inverse problem, so we can first calculate h. RC,k and h RL,k Discretization, with h RL,k For example:

[0070]

[0071] Where, x m Let φ be the weighting coefficient to be determined. m (lnτ) is a discrete basic function.

[0072] Therefore, Z(ω) can be transformed into the following functional form:

[0073]

[0074] Among them, e z (ω) represents the discretization error.

[0075] And variable x m It can be estimated by minimizing the following objective function S(x):

[0076]

[0077] Among them, Z exp (ω a This corresponds to the impedance spectrum test data, Z. model (x,ω a This corresponds to the simulated impedance spectrum data, where x is a P-dimensional weight vector, i.e., x = [x1, x2, ..., x]. p ].

[0078] Alternatively, the above formula can be written as:

[0079]

[0080]

[0081]

[0082] Where P(x) is the penalty term, the optimal solution x can be obtained when the contour line of the objective function intersects the penalty term function for the first time, and then h can be obtained. RC,k (τ k ) and hRL,k (τ k ).

[0083] Then, based on the number, position, and area of ​​peaks in their characteristic curves, different RC models and RL models, as well as other model parameters, can be distinguished.

[0084] Step S130: Determine the number of polarized inductances in the resistance and inductance impedance based on the number of peaks in the characteristic curve of the fitted relaxation time distribution of the resistance and inductance impedance.

[0085] In one embodiment, reference can be made to Figure 4 The figure shows the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance. It can be seen that there is only one peak in this characteristic curve. Therefore, the number of polarized inductance in the resistor-inductor impedance is 1.

[0086] Step S140: Based on the number of polarized inductor impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance, determine the impedance of each polarized inductor impedance corresponding to each peak in the resistor-inductor impedance.

[0087] In this step, different inductor polarization behaviors can be identified by the number of peaks, peak positions, and peak areas, and the impedance resulting from a specific inductor polarization behavior can be calculated. Since conventional Nyquist plot fitting curves cannot accurately represent polarization behaviors with lower impedance when dealing with complex high-order equivalent circuit models, the impedance determination method provided by this invention allows those skilled in the art to accurately and quickly analyze electrochemical AC impedance spectra.

[0088] Specifically, for each peak in the characteristic curve caused by a specific polarization behavior, the X-axis coordinate of the highest point of the peak curve can be taken according to the peak position of each peak. Then, the impedance value of the impedance curve corresponding to each polarization inductor impedance of each peak is the area integral of that peak curve with the X-axis. Therefore, the impedance of a specific RC model or RL model can be obtained by the peak area integral of different peaks in the characteristic curve.

[0089] In one embodiment, step S140 may include step S141 or S142, for determining the impedance of each polarized inductor impedance according to different situations.

[0090] Step S141: If the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance includes a peak, the impedance of the polarized inductor impedance in the resistor-inductor impedance is determined as the integral value of the area below the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance.

[0091] Step S142: When the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance includes multiple peaks, the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance is decomposed into multiple peak curves corresponding to the multiple peaks, and the impedance of each polarized inductor impedance in the resistor-inductor impedance is determined as the integral value of the area below the corresponding peak curve.

[0092] In one embodiment, reference can be made to Figure 4 .because Figure 4 Since there is only one peak, the impedance of the polarized inductance in the resistor-inductor impedance in this embodiment is the integral value of the area of ​​the entire area below the characteristic curve in the figure.

[0093] Compared with the prior art, the present invention has the following advantages:

[0094] (1) This invention can perform polarization characteristic analysis on the measured electrochemical impedance spectroscopy without preprocessing the equivalent circuit model of the energy storage device. The characteristic parameters of each polarization peak inside the energy storage device can be obtained in a single calculation, which can effectively reduce the workload of data processing. Furthermore, this invention identifies polarization behavior by recognizing peaks in the characteristic curve, which can distinguish various polarization behaviors in complex electrochemical systems and quantify extremely low impedance values ​​that are difficult to obtain in ordinary electrochemical impedance spectroscopy. Even those who are not familiar with Nyquist plots can intuitively understand the polarization characteristics inside the system.

[0095] (2) This invention innovatively incorporates inductive components into the relaxation time distribution function, and plots relaxation time distribution function curves including resistive and inductive components and resistive and capacitive components. This can fully extend the relaxation time distribution analysis method to other energy storage device characterization and testing fields, making the application range of electrochemical AC impedance spectroscopy wider.

[0096] In one embodiment, the determination method S100 may further include steps S150-S170.

[0097] Step S150: Determine the fitting relaxation time distribution characteristic curve of the resistor-capacitor impedance based on the relaxation time distribution function.

[0098] In one embodiment, the relaxation time distribution function can be solved by using the Gaussian distribution method and the Tikhonov regularization method to obtain the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance. The specific calculation process can be referred to in step S120 for calculating the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance, and will not be repeated here.

[0099] Step S160: Determine the number of polarized capacitor impedances in the resistor-capacitor impedance based on the number of peaks in the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance.

[0100] In one embodiment, reference can be made to Figure 5 The figure shows the fitted relaxation time distribution characteristic curve of the resistance-capacitance impedance. It can be seen that there are 7 peaks in this characteristic curve; therefore, the number of polarization capacitance impedances in the resistance-capacitance impedance is 7. From left to right, they are: 1 - double-layer capacitance effect peak; 2 - peak caused by ion migration through the negative electrode SEI film; 3 - charge transfer reaction peak occurring at the negative electrode; 4 - charge transfer reaction peak occurring at the positive electrode; 5-7 are all constant-phase diffusion peaks.

[0101] Step S170: Based on the number of polarization capacitor impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance, determine the impedance of each polarization capacitor impedance corresponding to each peak in the resistor-capacitor impedance.

[0102] In this step, different capacitive polarization behaviors can be identified by the number of peaks, peak positions, and peak areas, and the impedance resulting from a specific capacitive polarization behavior can be calculated.

[0103] In one embodiment, step S170 may include step S171 or S172, for determining the impedance of each polarization capacitor according to different situations.

[0104] Step S171: If the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance includes a peak, the impedance of the polarized capacitor impedance in the resistor-capacitor impedance is determined as the integral value of the area below the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance.

[0105] Step S172: When the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance may include multiple peaks, the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance is decomposed into multiple peak curves corresponding to multiple peaks, and the impedance of each polarized capacitor impedance in the resistor-capacitor impedance is determined as the integral value of the area below the corresponding peak curve.

[0106] In one embodiment, reference can be made to Figure 5 .because Figure 5 There are 7 peaks. Therefore, in this embodiment, the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance is decomposed into 7 peak curves corresponding to these 7 peaks. The impedance of each polarized capacitor impedance in the resistor-capacitor impedance is determined as the integral value of the area of ​​the region below the corresponding peak curve, thereby obtaining the impedance of each polarized capacitor impedance in the 7 polarized capacitor impedances.

[0107] On the other hand, the present invention also provides a polarization impedance determination system 200, such as... Figure 6 As shown, determining system 200 may include:

[0108] The objective function determination device 210 is used to determine the relaxation time distribution function with resistance-capacitance impedance and resistance-inductance impedance as variables based on the electrochemical AC impedance spectrum of the target energy storage device under a set excitation, wherein the resistance-capacitance impedance and resistance-inductance impedance are related to the angular frequency of the set excitation.

[0109] The first characteristic curve determining device 220 is used to determine the fitting relaxation time distribution characteristic curve of the resistance and inductance impedance based on the relaxation time distribution function.

[0110] The first number determination device 230 is used to determine the number of polarized inductance impedances in the resistance-inductance impedance based on the number of peaks in the fitted relaxation time distribution characteristic curve of the resistance-inductance impedance; and

[0111] The first impedance determination device 240 is used to determine the impedance of each polarized inductor impedance corresponding to each peak in the resistive inductor impedance based on the number of polarized inductor impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistive inductor impedance.

[0112] In one embodiment, the determination system 200 of this application may further include:

[0113] The second characteristic curve determining device 250 is used to determine the fitting relaxation time distribution characteristic curve of the resistor-capacitor impedance based on the relaxation time distribution function.

[0114] The second number determination device 260 is used to determine the number of polarized capacitor impedances in the resistor-capacitor impedance based on the number of peaks in the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance; and

[0115] The second impedance determination device 270 is used to determine the impedance of each polarized capacitor impedance corresponding to each peak in the resistor-capacitor impedance based on the number of polarized capacitor impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance.

[0116] The beneficial effects of the polarization impedance determination system of the present invention can be referred to the above description of the polarization impedance determination method, and will not be repeated here.

[0117] This invention also provides a machine-readable storage medium storing instructions for causing a machine to execute: the polarization impedance determination method as described above.

[0118] This invention provides a processor for running a program, wherein the program is executed to perform: a method for determining polarization impedance as described above.

[0119] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 7 As shown. The computer device includes a processor A01, a network interface A02, a display screen A04, an input device A05, and a memory (not shown) connected via a system bus. The processor A01 provides computing and control capabilities. The memory includes internal memory A03 and a non-volatile storage medium A06. The non-volatile storage medium A06 stores an operating system B01 and a computer program B02. The internal memory A03 provides an environment for the operation of the operating system B01 and the computer program B02 stored in the non-volatile storage medium A06. The network interface A02 is used for communication with external terminals via a network connection. When the computer program is executed by the processor A01, it implements a method for determining polarization impedance. The display screen A04 can be a liquid crystal display (LCD) or an e-ink display. The input device A05 can be a touch layer covering the display screen, buttons, a trackball, or a touchpad mounted on the computer device casing, or an external keyboard, touchpad, or mouse.

[0120] Those skilled in the art will understand that Figure 7 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0121] In one embodiment, the polarization impedance determination system 200 provided in this application can be implemented as a computer program, which can be configured as follows: Figure 7 The computer device shown is running on this system. The computer device's memory can store the various program modules that make up the system 200 for determining the polarization impedance, for example, Figure 6 The illustrated device includes an objective function determination device 210, a first characteristic curve determination device 220, a first number determination device 230, and a first impedance determination device 240. The computer program, comprised of these various program modules, causes the processor to execute the steps in the polarization impedance determination methods of the various embodiments of this application described in this specification.

[0122] Figure 7 The computer device shown can be used as follows Figure 6The objective function determination device 210 in the polarization impedance determination system 200 shown executes step S110, the first characteristic curve determination device 220 executes step S120, the first number determination device 230 executes step S130, and the first impedance determination device 240 executes step S140.

[0123] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0124] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0125] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0126] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0127] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0128] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, like read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0129] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0130] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0131] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for determining polarization impedance, characterized in that, The determination method includes: Based on the electrochemical AC impedance spectrum of the target energy storage device under a set excitation, the relaxation time distribution function with resistance-capacitance impedance and resistance-inductance impedance as variables is determined, wherein the resistance-capacitance impedance and the resistance-inductance impedance are related to the angular frequency of the set excitation. Based on the relaxation time distribution function, determine the fitted relaxation time distribution characteristic curve of the resistor and inductor impedance; Based on the number of peaks in the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance, determine the number of polarized inductance impedances in the resistor-inductor impedance; and The impedance of each polarized inductor impedance corresponding to each peak is determined based on the number of polarized inductor impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance.

2. The determination method according to claim 1, characterized in that, The impedance of each polarized inductor is determined by the following method: If the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance includes a peak, the impedance of the polarized inductor impedance in the resistor-inductor impedance is determined as the integral value of the area below the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance; or When the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance includes multiple peaks, the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance is decomposed into multiple peak curves corresponding to the multiple peaks, and the impedance of each polarized inductor impedance in the resistor-inductor impedance is determined as the integral value of the area of ​​the region below the corresponding peak curve.

3. The determination method according to claim 1, characterized in that, The determination method further includes: Based on the relaxation time distribution function, determine the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance; Based on the number of peaks in the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance, determine the number of polarization capacitor impedances in the resistor-capacitor impedance; and The impedance of each polarized capacitor impedance corresponding to each peak is determined based on the number of polarized capacitor impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance.

4. The determination method according to claim 3, characterized in that, The impedance of each polarized capacitor is determined by the following method: If the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance includes a peak, the impedance of the polarized capacitor impedance in the resistor-capacitor impedance is determined as the integral value of the area below the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance. or When the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance includes multiple peaks, the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance is decomposed into multiple peak curves corresponding to the multiple peaks, and the impedance of each polarized capacitor impedance in the resistor-capacitor impedance is determined as the integral value of the area of ​​the region below the corresponding peak curve.

5. The determination method according to claim 1, characterized in that, The relaxation time distribution function is expressed by the following equation: Among them, h RC,k h is the characteristic value of the relaxation time distribution of the impedance of the Nth resistor-capacitor circuit. RL,k Let τ be the characteristic value of the relaxation time distribution of the impedance of the Nth resistor-inductor circuit. k For the Nth relaxation time, R Ω Let ω be the lumped resistance of the target energy storage device, C be the lumped capacitance of the target energy storage device, L be the lumped inductance of the target energy storage device, ω be the angular frequency of the set excitation, and j be a complex unit.

6. The determination method according to claim 1, characterized in that, The method for obtaining the fitting relaxation time distribution characteristic curve of the resistor-inductor impedance includes: Based on the relaxation time distribution function, the fitted relaxation time distribution characteristic curve of the resistor and inductor impedance is obtained by using the Gaussian distribution method and the Tikhonov regularization method.

7. The determination method according to claim 1, characterized in that, The target energy storage device includes: lithium-ion battery, double-layer capacitor or flow battery.

8. A system for determining polarization impedance, characterized in that, The determining system includes: The objective function determination device is used to determine the relaxation time distribution function with resistance-capacitance impedance and resistance-inductance impedance as variables based on the electrochemical AC impedance spectrum of the target energy storage device under a set excitation, wherein the resistance-capacitance impedance and the resistance-inductance impedance are related to the angular frequency of the set excitation. The first characteristic curve determining device is used to determine the fitted relaxation time distribution characteristic curve of the resistor-inductor impedance based on the relaxation time distribution function. A first number determination device is used to determine the number of polarized inductance impedances in the resistor-inductance impedance based on the number of peaks in the fitted relaxation time distribution characteristic curve of the resistor-inductance impedance; and The first impedance determination device is used to determine the impedance of each polarized inductor impedance corresponding to each peak in the resistive inductor impedance based on the number of polarized inductor impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistive inductor impedance.

9. The determining system according to claim 8, characterized in that, The determining system further includes: The second characteristic curve determining device is used to determine the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance based on the relaxation time distribution function. The second number determination device is used to determine the number of polarized capacitor impedances in the resistor-capacitor impedance based on the number of peaks in the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance; and The second impedance determination device is used to determine the impedance of each polarized capacitor impedance corresponding to each peak in the resistor-capacitor impedance based on the number of polarized capacitor impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistor-capacitor impedance.

10. A machine-readable storage medium, characterized in that, The machine-readable storage medium stores instructions for causing the machine to perform: the method for determining polarization impedance according to any one of claims 1-7.

Images