Polarization impedance determination method and system and machine readable storage medium

Abstract

The embodiment of the invention provides a polarization impedance determination method and system and a machine readable storage medium, and belongs to the field of energy storage analysis. The determination method comprises the following steps: determining a relaxation time distribution function taking resistance-capacitance impedance and resistance-inductance impedance as variables according to an electrochemical alternating-current impedance spectrum of a target energy storage device under set excitation; further determining a fitting relaxation time distribution characteristic curve of the resistance and inductance impedance; and according to the number of peaks in the fitting relaxation time distribution characteristic curve and the area of a region below a peak curve corresponding to each peak, determining the impedance quantity of each polarization inductance impedance corresponding to each peak. According to the determination method, under the condition that equivalent circuit model pretreatment is not carried out on the energy storage device, polarization characteristic analysis can be carried out on the measured electrochemical alternating-current impedance spectrum, and the data processing workload can be effectively reduced. Meanwhile, the method for determining the polarization impedance can expand the application range of the electrochemical alternating-current impedance spectrum.

Description

Technical Field

[0001] The present invention relates to the field of energy storage analysis, and in particular to a method and system for determining polarization impedance and a machine-readable storage medium. Background Art

[0002] The depletion of fossil energy is considered one of the most pressing social problems to be solved in this century. The technology industry for renewable energy is flourishing all over the world. The progress of electrochemical energy storage technology, especially the huge performance improvement brought by the iteration of lithium-ion battery technology, has indirectly promoted the development of energy science. However, electrochemical energy storage devices, including lithium-ion batteries, often have various problems in actual working environments, such as the rapid shortening of cycle life in low temperature environments or the reduction of available capacity under high rate currents.

[0003] Electrochemical impedance spectroscopy is a widely used characterization method for analyzing the internal kinetic processes of electrochemical systems. However, due to its complex principles, many interference factors, and large amount of data processing, it often leads to erroneous characterization results. The core problem is that when analyzing electrochemical impedance spectroscopy, the system needs to be pre-processed to convert the equivalent circuit model. This pre-processing work requires relevant personnel to complete the construction of the equivalent circuit model based on experience summary, which is easily affected by subjective consciousness and outputs unreasonable models.

[0004] In addition, faced with complex high-order equivalent circuit models, the conventional Nyquist plot fitting curve cannot reflect the polarization behavior with smaller impedance, and it is difficult to quantify the extremely low impedance values ​​in the electrochemical AC impedance spectrum. Summary of the invention

[0005] The purpose of the embodiments of the present invention is to provide a method for determining polarization impedance, a determination system, and a machine-readable storage medium. By adopting the method for determining polarization impedance of the present invention, the polarization characteristics of the measured electrochemical AC impedance spectrum can be analyzed without pre-processing the energy storage device with an equivalent circuit model, which can effectively reduce the workload of data processing. At the same time, the method for determining polarization impedance of the present invention can also expand the application scope of electrochemical AC impedance spectroscopy.

[0006] In order to achieve the above-mentioned purpose, an embodiment of the present invention first provides a method for determining polarization impedance, the determination method comprising: determining a relaxation time distribution function with resistance-capacitance impedance and resistance-inductance impedance as variables according to an electrochemical alternating current impedance spectrum of a 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; determining a fitting relaxation time distribution characteristic curve of the resistance-inductance impedance according to the relaxation time distribution function; determining the number of polarization inductance impedances in the resistance-inductance impedance according to the number of peaks in the fitting relaxation time distribution characteristic curve of the resistance-inductance impedance; and determining the impedance amount of each polarization inductance impedance corresponding to each peak in the resistance-inductance impedance according to the number of polarization inductance impedances and the area below the peak curve corresponding to each peak in the fitting relaxation time distribution characteristic curve of the resistance-inductance impedance.

[0007] Optionally, the impedance amount of each polarized inductance impedance is determined by the following method: when the fitting relaxation time distribution characteristic curve of the resistance and inductance impedance includes one peak, the impedance amount of the polarized inductance impedance in the resistance and inductance impedance is determined as the integral value of the area below the fitting relaxation time distribution characteristic curve of the resistance and inductance impedance; or when the fitting relaxation time distribution characteristic curve of the resistance and inductance impedance includes multiple peaks, the fitting relaxation time distribution characteristic curve of the resistance and inductance impedance is decomposed into multiple peak curves corresponding to the multiple peaks, and the impedance amount of each polarized inductance impedance in the resistance and inductance impedance is determined as the integral value of the area below the corresponding peak curve.

[0008] Optionally, the determination method also includes: determining a fitted relaxation time distribution characteristic curve of the resistance and capacitance impedance according to the relaxation time distribution function; determining the number of polarization capacitance impedances in the resistance and capacitance impedance according to the number of peaks in the fitted relaxation time distribution characteristic curve of the resistance and capacitance impedance; and determining the impedance amount of each polarization capacitance impedance corresponding to each peak in the resistance and capacitance impedance according to the number of polarization capacitance impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistance and capacitance impedance.

[0009] Optionally, the impedance amount of each polarized capacitor impedance is determined by the following method: when the fitting relaxation time distribution characteristic curve of the resistor and capacitor impedance includes one peak, the impedance amount of the polarized capacitor impedance in the resistor and capacitor impedance is determined as the integral value of the area below the fitting relaxation time distribution characteristic curve of the resistor and capacitor impedance; or when the fitting relaxation time distribution characteristic curve of the resistor and capacitor impedance includes multiple peaks, the fitting relaxation time distribution characteristic curve of the resistor and capacitor impedance is decomposed into multiple peak curves corresponding to the multiple peaks, and the impedance amount of each polarized capacitor impedance in the resistor and 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 as follows:

[0011]

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

[0013] Optionally, the method for obtaining the fitted relaxation time distribution characteristic curve of the resistance and inductance impedance includes: according to the relaxation time distribution function, obtaining the fitted relaxation time distribution characteristic curve of the resistance and inductance impedance by using a Gaussian distribution method and a Tikhonov regularization method.

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

[0015] On the other hand, an embodiment of the present invention further provides a system for determining polarization impedance, the determination system comprising: an objective function determination device, for determining a relaxation time distribution function with resistance-capacitance impedance and resistance-inductance impedance as variables according to an electrochemical AC impedance spectrum of a 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; a first characteristic curve determination device, for determining a fitted relaxation time distribution characteristic curve of the resistance-inductance impedance according to the relaxation time distribution function; a first number determination device, for determining the number of polarization inductance impedances in the resistance-inductance impedance according to the number of peaks in the fitted relaxation time distribution characteristic curve of the resistance-inductance impedance; and a first impedance quantity determination device, for determining the impedance quantity of each polarization inductance impedance corresponding to each peak in the resistance-inductance impedance according to the number of polarization inductance impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistance-inductance impedance.

[0016] Optionally, the determination system also includes: a second characteristic curve determination device, used to determine the fitted relaxation time distribution characteristic curve of the resistor and capacitor impedance according to the relaxation time distribution function; a second number determination device, used to determine the number of polarization capacitor impedances in the resistor and capacitor impedance according to the number of peaks in the fitted relaxation time distribution characteristic curve of the resistor and capacitor impedance; and a second impedance quantity determination device, used to determine the impedance quantity of each polarization capacitor impedance corresponding to each peak in the resistor and capacitor impedance according to 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 and capacitor impedance.

[0017] On the other hand, an embodiment of the present invention further provides a machine-readable storage medium, on which instructions are stored, and the instructions are used to enable a machine to execute any of the above-mentioned methods for determining polarization impedance.

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

[0019] (1) The present invention can analyze the polarization characteristics of the measured electrochemical AC impedance spectrum without pre-processing the energy storage device with an equivalent circuit model, and can obtain the characteristic parameters of each polarization peak inside the energy storage device through only one calculation, which can effectively reduce the workload of data processing. In addition, the present invention can identify polarization behavior by identifying the peaks in the characteristic curve, distinguish various polarization behaviors in complex electrochemical systems, and quantify extremely low impedance values ​​that are difficult to obtain in ordinary electrochemical AC impedance spectra. Even people who are not familiar with the Nyquist diagram can intuitively understand the polarization characteristics inside the system;

[0020] (2) The present invention innovatively incorporates inductance components into the relaxation time distribution function, and draws a relaxation time distribution function curve including resistance and inductance components and resistance and capacitance components. This can fully expand the relaxation time distribution analysis method to other energy storage device characterization and testing fields, making the application scope 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 subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0023] Figure 1 is a flow chart of a method for determining polarization impedance provided according to an embodiment of the present application;

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

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

[0026] Figure 4 is a schematic diagram of relaxation time distribution for resistor and inductor elements provided according to an embodiment of the present application;

[0027] Figure 5 is a schematic diagram of relaxation time distribution for resistor and capacitor elements provided according to an embodiment of the present application;

[0028] Figure 6 is a schematic diagram of a system for determining polarization impedance provided according to an embodiment of the present application;

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

[0030] Description of Reference Numerals

[0031] 200-Determination system of polarization impedance;

[0032] 210 - an objective function determining device, 220 - a first characteristic curve determining device, 230 - a first number determining device, 240 - a first impedance determining device, 250 - a second characteristic curve determining device, 260 - a second number determining device, 270 - a second impedance determining 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 DESCRIPTION

[0035] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0036] The present 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, determining a relaxation time distribution function with resistance-capacitance impedance and resistance-inductance impedance as variables according to the electrochemical AC impedance spectrum of the target energy storage device under the set excitation, wherein the resistance-capacitance impedance and the resistance-inductance impedance are related to the angular frequency of the set excitation.

[0038] In one embodiment, the target energy storage device may include: lithium ion battery, double layer capacitor or liquid flow battery, etc. Therefore, the method for determining polarization impedance of the present invention can be extended to fields other than lithium ion battery, such as double layer capacitor, liquid flow battery, etc.

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

[0040] Step S111, obtaining the electrochemical impedance spectrum of the target energy storage device under a set excitation.

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

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

[0043] Z(ω)=X(ω) / J(ω),

[0044] Z(ω)=Z'(ω)+jZ”(ω),

[0045] Wherein, J(ω) is the AC excitation selected in the electrochemical AC impedance spectroscopy test, X(ω) is the AC response selected in the electrochemical AC impedance spectroscopy test, ω is the angular frequency of the excitation selected in the electrochemical AC impedance spectroscopy test, Z(ω) is the AC impedance of the system to be tested, Z'(ω) is the real part of the electrochemical AC impedance of the system to be tested, Z”(ω) is the imaginary part of the electrochemical AC impedance of the system to be tested, and j is a complex unit.

[0046] Step S112, establishing a relaxation time distribution function of the electrochemical impedance spectroscopy.

[0047] Among them, the relaxation time distribution function established by the present invention takes resistance capacitance impedance and resistance inductance impedance as variables. That is to say, compared with the energy storage device mainly based on capacitance elements in the prior art, the present invention further adds inductance elements including inductance and resistance inductance elements. Among them, capacitance elements can be applied to the characterization of lithium electronic batteries, and the addition of inductance elements can be better applied to the field of electrochemical testing technology, thereby expanding the actual application range.

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

[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 relationship between other components and impedance is as follows:

[0052] For resistance, Z = R;

[0053] For inductance, Z = jωL;

[0054] For capacitance, Z = 1 / (jωC);

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

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

[0057] In one embodiment, in combination with the algebraic relationship between the above elements and the impedance, the established relaxation time distribution function can be expressed as follows:

[0058]

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

[0060] Among them, the physical meaning of the relaxation time distribution function is to characterize the internal dynamic process of the electrochemical system, which is equivalent to constructing Figure 3 The equivalent circuit model shown in FIG. However, compared with the traditional method of constructing an equivalent circuit model, the method of the present invention can reduce the workload of analyzing the spectrum of the electrochemical AC impedance spectrum, and can also respectively reflect the resistance effect, capacitance effect, inductance effect, resistance-capacitance effect and resistance-inductance effect, thereby expanding the actual application range. For example, it can be expanded to fields other than lithium-ion batteries, such as double-layer capacitors, liquid flow batteries, etc.

[0061] Step S120, determining a fitted relaxation time distribution characteristic curve of the resistance and inductance impedance according to the relaxation time distribution function.

[0062] In one embodiment, the inverse problem of the relaxation time distribution function can be solved by using the Gaussian distribution method and the Tychonov regularization method to obtain a fitted relaxation time distribution characteristic curve of the resistance and inductance 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 and capacitance circuit impedance of the system to be measured can be output respectively. RC,k (τ) and the resulting matrix h of the relaxation time distribution of the impedance of the resistor-inductor circuit RL,k (ω).

[0064] Specifically, log 10 τ k is the horizontal axis, h RC,k (ω k ) or h RL,k (τ k ) as the ordinate, and the corresponding fitting relaxation time distribution characteristic curves of resistance and capacitance impedance and resistance and inductance impedance are drawn respectively. The two characteristic curves obtained are as follows Figure 4 and Figure 5 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. RC,k and h RL,k Discretization, h RL,k For example:

[0070]

[0071] Among them, x m is the weight coefficient to be determined, φ m (lnτ) is a discrete primitive function.

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

[0073]

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

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

[0076]

[0077] Among them, Z exp (ω a ) corresponds to the test data of the impedance spectrum, Z model (x,ω a ) corresponds to the simulation data of the impedance spectrum, and x is the P-dimensional weight vector, that is, x = [x 1 ,x 2 ,..,x p ].

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

[0079]

[0080]

[0081]

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

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

[0084] Step S130, determining the number of polarization inductance impedances in the resistance and inductance impedance according to the number of peaks in the fitted relaxation time distribution characteristic curve of the resistance and inductance impedance.

[0085] In one embodiment, reference may be made to Figure 4 , shows the fitting relaxation time distribution characteristic curve of the resistance and inductance impedance. It can be seen that there is only one peak in the characteristic curve, so the number of polarization inductance impedance in the resistance and inductance impedance is 1.

[0086] Step S140, determining the impedance of each polarized inductor impedance corresponding to each peak in the resistance and inductance impedance according to 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 resistance and inductance 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 caused by specific inductor polarization behaviors can be calculated. Because the conventional Nyquist plot fitting curve cannot reflect the polarization behavior with smaller impedance when the technicians in this field are faced with complex high-order equivalent circuit models. Therefore, by using the impedance determination method provided by the present invention, the technicians in this field can accurately and quickly complete the analysis of the electrochemical AC impedance spectrum.

[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, and the impedance value of the impedance curve of each polarized inductance impedance corresponding to each peak is the area integral of the peak curve and the X-axis. Therefore, the impedance value of a specific RC model or RL model can be obtained according to the peak area integral of different peaks in the characteristic curve.

[0089] In one embodiment, step S140 may include step S141 or S142, which is used to determine the impedance value of each polarized inductor impedance according to different situations.

[0090] Step S141, when the fitted relaxation time distribution characteristic curve of the resistance and inductance impedance includes a peak, the impedance amount of the polarization inductance impedance in the resistance and inductance impedance is determined as the integral value of the area below the fitted relaxation time distribution characteristic curve of the resistance and inductance impedance.

[0091] Step S142, when the fitting relaxation time distribution characteristic curve of the resistance and inductance impedance includes multiple peaks, decompose the fitting relaxation time distribution characteristic curve of the resistance and inductance impedance into multiple peak curves corresponding to the multiple peaks, and determine the impedance amount of each polarization inductance impedance in the resistance and inductance impedance as the integral value of the area below the corresponding peak curve.

[0092] In one embodiment, reference may be made to Figure 4 .because Figure 4 There is only one peak in the figure, so the impedance of the polarization inductance impedance in the resistance and inductance impedance in this embodiment is the integral value of the area of ​​the entire lower region of the characteristic curve in the figure.

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

[0094] (1) The present invention can analyze the polarization characteristics of the measured electrochemical AC impedance spectrum without pre-processing the energy storage device with an equivalent circuit model, and can obtain the characteristic parameters of each polarization peak inside the energy storage device through only one calculation, which can effectively reduce the workload of data processing. In addition, the present invention can identify polarization behavior by identifying the peaks in the characteristic curve, distinguish various polarization behaviors in complex electrochemical systems, and quantify extremely low impedance values ​​that are difficult to obtain in ordinary electrochemical AC impedance spectra. Even people who are not familiar with the Nyquist diagram can intuitively understand the polarization characteristics inside the system;

[0095] (2) The present invention innovatively incorporates inductance components into the relaxation time distribution function, and draws a relaxation time distribution function curve including resistance and inductance components and resistance and capacitance components. This can fully expand the relaxation time distribution analysis method to other energy storage device characterization and testing fields, making the application scope of electrochemical AC impedance spectroscopy wider.

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

[0097] Step S150, determining a fitted relaxation time distribution characteristic curve of the resistance and capacitance impedance according to the relaxation time distribution function.

[0098] In one embodiment, the relaxation time distribution function can be solved by the Gaussian distribution method and the Tikhonov regularization method to obtain the fitting relaxation time distribution characteristic curve of the resistance and capacitance impedance. The specific calculation process can refer to the calculation of the fitting relaxation time distribution characteristic curve of the resistance and capacitance impedance in step S120, which will not be repeated here.

[0099] Step S160, determining the number of polarized capacitance impedances in the resistance and capacitance impedances according to the number of peaks in the fitted relaxation time distribution characteristic curve of the resistance and capacitance impedances.

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

[0101] Step S170, determining the impedance value of each polarized capacitance impedance corresponding to each peak in the resistance and capacitance impedance according to the number of polarized capacitance impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistance and capacitance impedance.

[0102] In this step, different capacitor polarization behaviors can be identified by the number of peaks, peak positions, and peak areas, and the impedance caused by specific capacitor polarization behaviors can be calculated.

[0103] In one embodiment, step S170 may include step S171 or S172, which is used to determine the impedance value of each polarized capacitor impedance according to different situations.

[0104] Step S171, when the fitted relaxation time distribution characteristic curve of the resistance and capacitance impedance includes a peak, the impedance amount of the polarization capacitance impedance in the resistance and capacitance impedance is determined as the integral value of the area below the fitted relaxation time distribution characteristic curve of the resistance and capacitance impedance.

[0105] Step S172, when the fitting relaxation time distribution characteristic curve of the resistance and capacitance impedance may include multiple peaks, decompose the fitting relaxation time distribution characteristic curve of the resistance and capacitance impedance into multiple peak curves corresponding to the multiple peaks, and determine the impedance amount of each polarization capacitance impedance in the resistance and capacitance impedance as the integral value of the area below the corresponding peak curve.

[0106] In one embodiment, reference may be made to Figure 5 .because Figure 5 There are 7 peaks in it, therefore, in this embodiment, the fitting relaxation time distribution characteristic curve of the resistance and capacitance impedance is decomposed into 7 peak curves corresponding to the 7 peaks, and the impedance amount of each polarization capacitance impedance in the resistance and capacitance impedance is determined as the integral value of the area below each corresponding peak curve, thereby obtaining the impedance amount of each polarization capacitance impedance in the 7 polarization capacitance impedances.

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

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

[0109] The first characteristic curve determining means 220 is used to determine the fitted relaxation time distribution characteristic curve of the resistance and inductance impedance according to the relaxation time distribution function;

[0110] A first number determining means 230, for determining the number of polarization inductance impedances in the resistance and inductance impedance according to the number of peaks in the fitted relaxation time distribution characteristic curve of the resistance and inductance impedance; and

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

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

[0113] The second characteristic curve determining device 250 is used to determine the fitted relaxation time distribution characteristic curve of the resistance and capacitance impedance according to the relaxation time distribution function;

[0114] A second number determining means 260, for determining the number of polarized capacitance impedances in the resistance and capacitance impedances according to the number of peaks in the fitted relaxation time distribution characteristic curve of the resistance and capacitance impedances; and

[0115] The second impedance determination device 270 is used to determine the impedance amount of each polarized capacitor impedance corresponding to each peak in the resistor and capacitor impedance according to 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 and capacitor impedance.

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

[0117] An embodiment of the present invention further provides a machine-readable storage medium, on which instructions are stored, and the instructions are used to enable a machine to execute: according to the method for determining polarization impedance as described above.

[0118] An embodiment of the present invention provides a processor, which is used to run a program, wherein the program, when being run, is used to execute: the method for determining polarization impedance as described above.

[0119] In one embodiment, a computer device is provided. The computer device 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 in the figure) connected through a system bus. Among them, the processor A01 of the computer device is used to provide computing and control capabilities. The memory of the computer device includes an 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 in the non-volatile storage medium A06. The network interface A02 of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor A01, a method for determining polarization impedance is implemented. The display screen A04 of the computer device can be a liquid crystal display or an electronic ink display, and the input device A05 of the computer device can be a touch layer covered on the display screen, or a button, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

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

[0121] In one embodiment, the polarization impedance determination system 200 provided in the present application can be implemented in the form of a computer program. The computer program can be used in Figure 7 The computer device shown in the figure is run on the computer device. The memory of the computer device can store various program modules constituting the polarization impedance determination system 200, for example, Figure 6 The objective function determining device 210, the first characteristic curve determining device 220, the first number determining device 230, and the first impedance determining device 240 are shown. The computer program composed of various program modules enables the processor to execute the steps of the method for determining the polarization impedance of each embodiment of the present application described in this specification.

[0122] Figure 7 The computer device shown can be Figure 6In the polarization impedance determination system 200 shown, the objective function determination device 210 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 appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0124] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0125] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0126] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function 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] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0129] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules 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 technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0130] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0131] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for determining polarization impedance, characterized in that: The determination method comprises: Determine a relaxation time distribution function with resistance-capacitance impedance and resistance-inductance impedance as variables according to an electrochemical alternating current impedance spectrum of a target energy storage device under a set excitation, wherein the resistance-capacitance impedance and the resistance-inductance impedance are related to an angular frequency of the set excitation; Determining a fitting relaxation time distribution characteristic curve of the resistance and inductance impedance according to the relaxation time distribution function; Determining the number of polarization inductance impedances in the resistance and inductance impedance according to the number of peaks in the fitted relaxation time distribution characteristic curve of the resistance and inductance impedance; and According to the number of the polarized inductance impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistance and inductance impedance, the impedance amount of each polarized inductance impedance corresponding to each peak in the resistance and inductance impedance is determined.

2. The determination method according to claim 1, characterized in that: The impedance of each polarization inductance impedance is determined by the following method: When the fitting relaxation time distribution characteristic curve of the resistance and inductance impedance includes a peak, the impedance value of the polarization inductance impedance in the resistance and inductance impedance is determined as the integral value of the area below the fitting relaxation time distribution characteristic curve of the resistance and inductance impedance; or In the case where the fitting relaxation time distribution characteristic curve of the resistance and inductance impedance includes multiple peaks, the fitting relaxation time distribution characteristic curve of the resistance and inductance impedance is decomposed into multiple peak curves corresponding to the multiple peaks, and the impedance amount of each polarization inductance impedance in the resistance and inductance impedance is determined as the integral value of the area below the corresponding peak curve.

3. The determination method according to claim 1, characterized in that: The determination method further comprises: Determining a fitting relaxation time distribution characteristic curve of the resistance and capacitance impedance according to the relaxation time distribution function; Determining the number of polarization capacitance impedances in the resistance and capacitance impedances according to the number of peaks in the fitted relaxation time distribution characteristic curve of the resistance and capacitance impedances; and According to the number of the polarized capacitance impedances and the area below the peak curve corresponding to each peak in the fitted relaxation time distribution characteristic curve of the resistance and capacitance impedance, the impedance amount of each polarized capacitance impedance corresponding to each peak in the resistance and capacitance impedance is determined.

4. The determination method according to claim 3, characterized in that: The impedance of each polarized capacitance impedance is determined by the following method: When the fitting relaxation time distribution characteristic curve of the resistance and capacitance impedance includes a peak, the impedance amount of the polarization capacitance impedance in the resistance and capacitance impedance is determined as the integral value of the area below the fitting relaxation time distribution characteristic curve of the resistance and capacitance impedance; or In the case where the fitting relaxation time distribution characteristic curve of the resistance and capacitance impedance includes multiple peaks, the fitting relaxation time distribution characteristic curve of the resistance and capacitance impedance is decomposed into multiple peak curves corresponding to the multiple peaks, and the impedance amount of each polarization capacitance impedance in the resistance and capacitance impedance is determined as the integral value of the area below the corresponding peak curve.

5. The determination method according to claim 1, characterized in that: The relaxation time distribution function is expressed as follows: Among them, h RC,k is the relaxation time distribution characteristic value of the impedance of the Nth resistor-capacitor circuit, h RL,k is the relaxation time distribution characteristic value of the impedance of the Nth resistor-inductor circuit, τ k is the Nth relaxation time, R Ω is the lumped resistance of the target energy storage device, C is the lumped capacitance of the target energy storage device, L is the lumped inductance of the target energy storage device, ω is the angular frequency of the set excitation, and j is 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 resistance and inductance impedance includes: According to the relaxation time distribution function, a fitting relaxation time distribution characteristic curve of the resistance and inductance impedance is obtained by using a Gaussian distribution method and a Tikhonov regularization method.

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

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

9. The determination system according to claim 8, characterized in that: The determination system further comprises: A second characteristic curve determining device, used to determine a fitting relaxation time distribution characteristic curve of the resistance and capacitance impedance according to the relaxation time distribution function; A second number determining device, for determining the number of polarization capacitance impedances in the resistance and capacitance impedances according to the number of peaks in the fitted relaxation time distribution characteristic curve of the resistance and capacitance impedances; and The second impedance determination device is used to determine the impedance amount of each polarization capacitance impedance corresponding to each peak in the resistance and capacitance impedance according to the number of the polarization capacitance impedances and the area below the peak curve corresponding to each peak in the fitting relaxation time distribution characteristic curve of the resistance and capacitance impedance.

10. A machine-readable storage medium, characterized in that: The machine-readable storage medium stores instructions, which are used to enable the machine to execute: a method for determining polarization impedance according to any one of claims 1-7.

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