Electrochemical impedance spectroscopy measurement method, system, and electronic device

Abstract

The application provides a kind of electrochemical impedance spectroscopy measurement method, system and electronic equipment. By applying excitation current signal to the battery to be measured;Response voltage signal output by the battery to be measured in response to the excitation current signal is obtained, and the response voltage signal is sampled according to the preset sampling frequency to obtain the voltage sampling signal, and the excitation current signal is synchronously sampled according to the preset sampling frequency to obtain the current sampling signal. The voltage sampling signal and the current sampling signal are processed and converted from time domain to frequency domain to obtain the frequency domain voltage signal and the frequency domain current signal. The electrochemical impedance spectroscopy is obtained according to the frequency domain voltage signal and the frequency domain current signal. Since the frequency of the excitation current signal corresponds to the frequency of the impedance to be measured, the preset sampling frequency is an integer multiple of the frequency of the excitation current signal. Therefore, the data length of the voltage sampling signal and the current sampling signal is relatively short, which reduces the calculation amount of the electrochemical impedance spectroscopy. The storage capacity of the processing chip is saved, and the computing power performance is improved.

Description

Technical Field

[0001] This application relates to the field of battery management technology, and in particular to a method and system for measuring electrochemical impedance spectroscopy. Background Technology

[0002] Electrochemical impedance spectroscopy (EIS) is a core analytical technique for studying the frequency response characteristics of electrochemical systems. With the rapid development of new energy technologies, the industry's demand for characteristic analysis of batteries under dynamic operating conditions is increasing—EIS can describe the impedance characteristics of batteries over a wide frequency range, thus providing a direct reflection of the electrochemical processes within the battery. Therefore, its application in battery performance evaluation is becoming increasingly widespread.

[0003] In related technologies, EIS measurement schemes typically use square wave signals as the excitation source for the battery, acquiring the corresponding response signals. Thus, EIS can be obtained from the response signals and the square wave signals. However, these EIS measurement schemes suffer from the problem of large sample data volumes, significantly increasing the computational load. This poses stringent challenges to the storage capacity and computing power performance of the processing chip. Summary of the Invention

[0004] This application provides a method and system for measuring electrochemical impedance spectroscopy, which can reduce the amount of data sampling, save the storage capacity of the processing chip, save computing power, and make the computing performance controllable.

[0005] In a first aspect, this application provides a method for measuring electrochemical impedance spectroscopy, the method comprising:

[0006] Apply an excitation current signal to the battery under test;

[0007] The method involves acquiring the response voltage signal output by the battery under test in response to the excitation current signal, sampling the response voltage signal at a preset sampling frequency to obtain a voltage sampling signal, and synchronously sampling the excitation current signal at the preset sampling frequency to obtain a current sampling signal; wherein the frequency of the excitation current signal corresponds one-to-one with the frequency of the impedance to be measured in the electrochemical impedance spectrum of the battery under test, and the preset sampling frequency is an integer multiple of the frequency of the excitation current signal;

[0008] The voltage sampling signal and the current sampling signal are processed and converted from the time domain to the frequency domain to obtain the frequency domain voltage signal and the frequency domain current signal;

[0009] The electrochemical impedance spectrum is obtained based on the frequency domain voltage signal and the frequency domain current signal.

[0010] The electrochemical impedance spectroscopy (EIS) measurement method provided in the first aspect involves applying an excitation current signal to the battery under test (BUT) to obtain the response voltage signal output by the BUT in response to the excitation current signal. The response voltage signal is then sampled at a preset sampling frequency to obtain a voltage sampling signal, and the excitation current signal is simultaneously sampled at the same preset sampling frequency to obtain a current sampling signal. These voltage and current sampling signals are then processed and converted from the time domain to the frequency domain to obtain frequency-domain voltage and current signals. Furthermore, the EIS is obtained based on these frequency-domain voltage and current signals. Since the frequency of the excitation current signal corresponds one-to-one with the frequency of the impedance to be measured in the EIS, and the preset sampling frequency is an integer multiple of the frequency of the excitation current signal, the preset sampling frequency corresponds to the frequency of the impedance to be measured in the EIS. Therefore, the data lengths of both the voltage and current sampling signals are relatively short, significantly reducing the computational load of the EIS. This saves storage capacity and computing power in the processing chip, making the computing performance of the processing chip controllable.

[0011] In one possible design, when the frequency of the impedance under test is greater than or equal to a threshold frequency, the number of cycles of the excitation current signal is a second preset value, which is an integer greater than or equal to 5; when the frequency of the impedance under test is less than the threshold frequency, the number of cycles of the excitation current signal is one; wherein, the excitation current signal is a square wave current signal, and the duty cycle of the square wave current signal is 50%.

[0012] In one possible design, when the frequency of the impedance to be measured is greater than or equal to the threshold frequency, the preset sampling frequency is the first product result of the frequency of the excitation current signal multiplied by a first preset value; when the frequency of the impedance to be measured is less than the threshold frequency, the preset sampling frequency is the second product result, which is the product result of the first product result and a third preset value, where both the first preset value and the third preset value are integers greater than 1.

[0013] In one possible design, the time-domain to frequency-domain processing and conversion of the voltage and current sampling signals to obtain frequency-domain voltage and current signals includes:

[0014] Acquire an in-phase reference signal and a quadrature reference signal with the same frequency as the voltage sampling signal;

[0015] The frequency domain voltage signal is obtained based on the in-phase reference signal, the quadrature reference signal, and the voltage sampling signal;

[0016] The frequency domain current signal is obtained based on the in-phase reference signal, the quadrature reference signal, and the current sampling signal.

[0017] In one possible design, obtaining the frequency domain voltage signal based on the in-phase reference signal, the quadrature reference signal, and the voltage sampling signal includes:

[0018] Obtain the fundamental frequency voltage signal from the voltage sampling signal;

[0019] A first correlation parameter is obtained based on the in-phase reference signal and the fundamental frequency voltage signal, and a second correlation parameter is obtained based on the quadrature reference signal and the fundamental frequency voltage signal. The first correlation parameter is used to characterize the correlation between the in-phase reference signal and the fundamental frequency voltage signal, and the second correlation parameter is used to characterize the correlation between the quadrature reference signal and the fundamental frequency voltage signal.

[0020] The frequency domain voltage signal is obtained based on the first relevant parameter and the second relevant parameter.

[0021] In one possible design, the frequency domain voltage signal is obtained based on the first relevant parameter and the second relevant parameter, specifically according to the following formula:

[0022]

[0023]

[0024] in, A U5 The amplitude of the frequency domain voltage signal. R uyc1 For the first relevant parameter, R uys1 For the second relevant parameter, φ U4 The phase of the frequency domain voltage signal is denoted as .

[0025] In one possible design, obtaining the frequency domain current signal based on the in-phase reference signal, the quadrature reference signal, and the current sampling signal includes:

[0026] Obtain the fundamental frequency current signal from the current sampling signal;

[0027] A seventh correlation parameter is obtained based on the in-phase reference signal and the fundamental frequency current signal, and an eighth correlation parameter is obtained based on the quadrature reference signal and the fundamental frequency current signal. The seventh correlation parameter is used to characterize the correlation between the in-phase reference signal and the fundamental frequency current signal, and the eighth correlation parameter is used to characterize the correlation between the quadrature reference signal and the fundamental frequency current signal.

[0028] The frequency domain current signal is obtained based on the seventh and eighth related parameters.

[0029] In one possible design, the frequency domain current signal is obtained based on the seventh and eighth related parameters, specifically according to the following formula:

[0030]

[0031]

[0032] in, A I5 The amplitude of the frequency domain current signal is given. R iyc1 This is the seventh relevant parameter. R iys1 This is the eighth relevant parameter. φ I4 The phase of the frequency domain current signal is given.

[0033] In one possible design, obtaining the electrochemical impedance spectrum based on the frequency-domain voltage signal and the frequency-domain current signal includes:

[0034] Based on the frequency domain voltage signal and the frequency domain current signal, impedance data corresponding to the frequency of the impedance to be measured is obtained; wherein, the impedance data includes at least: impedance amplitude and impedance phase;

[0035] The electrochemical impedance spectrum is obtained based on the impedance data and the frequency of the impedance to be measured.

[0036] In one possible design, obtaining the impedance data corresponding to the frequency of the impedance to be measured based on the frequency-domain voltage signal and the frequency-domain current signal includes:

[0037] The ratio between the amplitude of the frequency domain voltage signal and the amplitude of the frequency domain current signal is determined as the impedance amplitude.

[0038] The difference between the phase of the frequency domain voltage signal and the phase of the frequency domain current signal is determined as the impedance phase.

[0039] In one possible design, the measurement method further includes:

[0040] Based on the impedance amplitude and the impedance phase, determine the real part and imaginary part of the impedance at the frequency of the impedance to be measured.

[0041] The accuracy of the impedance data is verified based on the real part of the impedance, the imaginary part of the impedance, the preset real part of the impedance, the preset imaginary part of the impedance, and the impedance amplitude.

[0042] Secondly, this application provides an electrochemical impedance spectroscopy measurement system, the measurement system comprising:

[0043] The excitation module is used to apply an excitation current signal to the battery under test.

[0044] The acquisition module is used to acquire the response voltage signal output by the battery under test in response to the excitation current signal, and to sample the response voltage signal at a preset sampling frequency to obtain a voltage sampling signal, and to synchronously sample the excitation current signal at the preset sampling frequency to obtain a current sampling signal; wherein, the frequency of the excitation current signal corresponds one-to-one with the frequency of the impedance to be measured in the electrochemical impedance spectrum of the battery under test, and the preset sampling frequency is an integer multiple of the frequency of the excitation current signal;

[0045] The conversion module is used to perform time-domain to frequency-domain processing and conversion on the voltage sampling signal and the current sampling signal to obtain a frequency-domain voltage signal and a frequency-domain current signal;

[0046] The processing module is used to obtain the electrochemical impedance spectrum based on the frequency domain voltage signal and the frequency domain current signal.

[0047] The beneficial effects of the measurement system provided in the second aspect and the various possible designs of the second aspect can be found in the first aspect and the various possible implementations of the first aspect, and will not be repeated here.

[0048] Thirdly, this application provides an electronic device. The electronic device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the steps of any of the methods described in the first aspect above.

[0049] Fourthly, this application provides a computer-readable storage medium storing a computer program, which is executed by a processor using the steps of any of the methods described in the first aspect.

[0050] Fifthly, this application provides a computer program product, comprising: a computer program stored in a computer-readable storage medium, at least one processor of an electronic device being able to read the computer program from the computer-readable storage medium, and the at least one processor executing the computer program to cause the electronic device to perform the steps of any of the methods in the first aspect above.

[0051] The above description is merely an overview of the technical solutions of the embodiments of this application. In order to better understand the technical means of the embodiments of this application and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of this application more obvious and understandable, specific implementation methods of this application are described below. Attached Figure Description

[0052] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a schematic diagram of the workflow of an electrochemical impedance spectroscopy measurement method in related technologies;

[0054] Figure 2 This is a schematic diagram of an electrochemical impedance spectroscopy technique.

[0055] Figure 3 A schematic flowchart illustrating an electrochemical impedance spectroscopy measurement method provided in this application embodiment;

[0056] Figure 4 A schematic diagram of the excitation current signal in an electrochemical impedance spectroscopy measurement method provided in this application embodiment. Figure 1 ;

[0057] Figure 5 A schematic diagram of the excitation current signal in an electrochemical impedance spectroscopy measurement method provided in this application embodiment. Figure 2 ;

[0058] Figure 6 A schematic diagram of the voltage sampling signal in an electrochemical impedance spectroscopy measurement method provided in this application embodiment;

[0059] Figure 7 A schematic flowchart of another electrochemical impedance spectroscopy measurement method provided in this application embodiment;

[0060] Figure 8 A schematic flowchart illustrating another electrochemical impedance spectroscopy measurement method provided in this application embodiment;

[0061] Figure 9 A schematic flowchart illustrating another electrochemical impedance spectroscopy measurement method provided in this application embodiment;

[0062] Figure 10 A schematic flowchart illustrating another electrochemical impedance spectroscopy measurement method provided in this application embodiment;

[0063] Figure 11 This is a schematic diagram of the structure of an electrochemical impedance spectroscopy measurement system provided in an embodiment of this application. Detailed Implementation

[0064] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c alone can mean: a alone, b alone, c alone, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0065] The terms “center,” “longitudinal,” “lateral,” “up,” “down,” “left,” “right,” “front,” and “rear,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0066] The terms "connected" and "connected" should be interpreted broadly. For example, in circuit structures, "connected" or "connected" can refer not only to physical connections but also to electrical or signal connections. This could be a direct connection (physical connection) or an indirect connection via at least one intermediate component, as long as the circuit is connected. It could also refer to the internal connection between two components. Similarly, a signal connection can refer to a connection via a circuit or a medium, such as radio waves. Those skilled in the art will understand the specific meaning of these terms in this application based on the specific circumstances.

[0067] First, the technical terms involved in the embodiments of this application will be explained.

[0068] Electrochemical impedance spectroscopy (EIS) is an electrochemical analysis technique based on the principle of linear small-signal perturbation. Its core is to apply a "sinusoidal AC small signal with a wide frequency range" to an electrochemical system (such as an electrode / electrolyte interface, battery, and sensor) and measure the "impedance response" of the system to signals of different frequencies. Then, the "impedance spectrum" is used to analyze the microscopic electrochemical information of the system, such as the interface structure, charge transfer process, and ion diffusion behavior. It is a core tool for studying the kinetics and interface properties of electrochemical systems and is widely used in fields such as batteries, corrosion, sensors, and electrocatalysis.

[0069] An electrochemical workstation, also known as an electrochemical integrated testing system, is a core instrument that integrates multiple electrochemical testing technologies and can precisely control and monitor electrochemical systems. Essentially, it achieves quantitative analysis and research of electrochemical processes by "precisely controlling electrode potential / current" and "acquiring response signals in real time," making it an indispensable "general-purpose testing platform" in both scientific research and industrial applications in the field of electrochemistry.

[0070] A square wave current signal is a periodic, non-sinusoidal pulse current signal. Its core characteristic is that the current amplitude jumps rapidly between two fixed values ​​and remains constant within each level interval. The overall waveform presents a periodic repetitive "rectangular (square)" shape and is widely used in fields such as electronic measurement, electrochemistry, power electronics, and communications.

[0071] The digital lock-in amplifier (LLP) algorithm is based on digital signal processing technology. Its core computational logic extracts weak target signals that are in phase and frequency with the reference signal from a background of strong noise. The core process involves three main steps: digital quadrature demodulation, digital filtering, and parameter calculation, to achieve high-precision measurement of the target signal's amplitude and phase. Essentially, it implements the hardware functions of traditional analog lock-in amplifiers, such as analog multipliers and RC low-pass filters, through software algorithms. This approach offers advantages such as high precision, strong anti-interference capabilities, and flexible parameter adjustment, making it widely applicable in weak signal detection scenarios such as spectral analysis, sensor detection, and quantum measurement.

[0072] SINK mode is typically a current-sinking mode. SINK mode is related to current direction; when a chip port is in SINK mode, the current flows from the external circuitry to the chip's interior. For example, in digital circuits, when the output is low, it draws current from the load; this current-drawing process is called SINK mode, and the current at this time is also known as current sinking.

[0073] The time domain is the core analytical dimension for describing the changes of signals or physical processes over time. It uses "time" as the horizontal axis and "signal amplitude (such as voltage, current, and sound intensity)" as the vertical axis, directly presenting "the specific value of a physical quantity at different times." Its essence is to record and analyze "the instantaneous changes and dynamic processes of signals over time."

[0074] The frequency domain describes the characteristics of a signal from the perspective of "frequency". It does not focus on the instantaneous changes of the signal over time, but rather on which "different frequency components" make up the signal, as well as the "intensity (amplitude)" and "phase" of each frequency component. Essentially, it decomposes the complex signal in the time domain into a superposition of simple sine waves.

[0075] Reference Figure 1 , Figure 1 This is a schematic diagram illustrating the workflow of an electrochemical impedance spectroscopy measurement method in related technologies. (Example:) Figure 1 As shown, the measurement method of electrochemical impedance spectroscopy usually involves applying a time-domain excitation current I(t) of a specific frequency to the battery and acquiring the time-domain response voltage V(t) corresponding to the time-domain excitation current I(t) to achieve the acquisition of the time-domain response voltage V(t).

[0076] Among them, the time-domain response voltage V(t) is the data source for measuring electrochemical impedance spectroscopy.

[0077] Since the electrochemical impedance spectroscopy is essentially the expression of the battery's internal resistance in the frequency domain, the time-domain excitation current I(t) and the time-domain response voltage V(t) are converted from the time domain to the frequency domain using a time-frequency conversion algorithm to obtain the frequency-domain excitation current I(f) and the frequency-domain response voltage U(f).

[0078] Thus, by determining the ratio of the frequency domain response voltage U(f) to the frequency domain excitation current I(f) as the impedance Z(f), the calculation results can be obtained, enabling the acquisition of... Figure 2 The electrochemical impedance spectroscopy shown is as follows: Figure 2 This is a schematic diagram of an electrochemical impedance spectroscopy technique.

[0079] The impedance Z(f) can be specifically expressed by formula (1):

[0080] Z(f)=U(f) / I(f)(1)

[0081] Where Z(f) is the impedance, U(f) is the frequency domain response voltage, and I(f) is the frequency domain excitation current.

[0082] Based on this, the electrochemical impedance spectroscopy was measured using an electrochemical workstation to obtain the test impedance. The impedance Z(f) was then compared with the test impedance to verify the calculation results. This allows for the determination of the accuracy of the calculation results and avoids the influence of factors such as signal sampling accuracy, excitation signal form, number of sampling points, and conversion algorithm on the calculation results.

[0083] One electrochemical impedance spectroscopy (EIS) measurement method in related technologies is primarily based on a dedicated chip. This chip can apply a complete sinusoidal AC excitation current to the battery via a charger, and calculate the EIS by analyzing this sinusoidal AC excitation current and the battery's response voltage. Such chips are specifically designed for automotive energy storage systems, belonging to the automotive chip field, and possess the ability to stably output sinusoidal AC excitation current. However, chips in the 3C consumer electronics field are limited by their processing power and hardware resources, making it difficult to generate a suitable sinusoidal AC excitation current. Therefore, the EIS measurement method based on this approach is difficult to effectively apply in the 3C field.

[0084] Therefore, in related technologies, electrochemical impedance spectroscopy (EIS) measurement schemes typically use square wave signals as the excitation source for the battery, acquiring the corresponding response signals. Thus, the EIS can be calculated from the response signals and the square wave signals. However, this EIS measurement scheme uses a fixed, high sampling frequency and a low-frequency square wave signal. Consequently, the EIS measurement scheme in related technologies suffers from a large amount of sampled data, significantly increasing the computational complexity. This poses a severe challenge to the storage capacity and computing power performance of the processing chip.

[0085] For example, the higher sampling frequency is 10 kHz and the lower frequency is 0.1 Hz. The higher sampling frequency depends on the high-frequency cutoff end of the electrochemical impedance spectroscopy, and the lower frequency depends on the low-frequency cutoff end of the electrochemical impedance spectroscopy.

[0086] To address the aforementioned problems, this application provides a method, system, and electronic device for measuring electrochemical impedance spectroscopy.

[0087] Reference Figure 3 , Figure 3 A schematic flowchart of an electrochemical impedance spectroscopy measurement method provided in this application embodiment is shown below. Figure 3 As shown, the method may include:

[0088] S101. Apply an excitation current signal to the battery under test.

[0089] S102. Obtain the response voltage signal output by the battery under test in response to the excitation current signal, and sample the response voltage signal according to the preset sampling frequency to obtain the voltage sampling signal, and synchronously sample the excitation current signal according to the preset sampling frequency to obtain the current sampling signal.

[0090] The frequency of the excitation current signal corresponds one-to-one with the frequency Fre of the impedance to be measured in the electrochemical impedance spectroscopy, and the preset sampling frequency... fs It is an integer multiple of the frequency of the excitation current signal.

[0091] The frequency Fre of the impedance to be measured is, for example, 1024Hz, 512Hz, 256Hz, ..., 0.25Hz, 0.125Hz. Correspondingly, the frequency of the excitation current signal is, for example, 1024Hz, 512Hz, 256Hz, ..., 0.25Hz, 0.125Hz. In other words, the period of the excitation current signal is, for example, 1 / 1024s, 1 / 512s, 1 / 256s, ..., 1 / 0.25s, 1 / 0.125s.

[0092] Electrochemical impedance spectroscopy typically consists of the impedance to be measured at multiple frequencies Fre. This means that the frequency of the excitation current signal differs for the impedance to be measured at different Fre frequencies. When the Fre frequency for the impedance to be measured is 0.25 Hz, the frequency of the excitation current signal is also 0.25 Hz. When the Fre frequency for the impedance to be measured is 1024 Hz, the frequency of the excitation current signal is also 1024 Hz.

[0093] For ease of explanation, the frequency Fre of the impedance to be measured in this embodiment is only 0.25Hz. Other Fre frequencies, such as 1024Hz, 512Hz, 256Hz, ..., 0.125Hz, are similar to 0.25Hz and will not be described in detail here.

[0094] S103. Perform time-domain to frequency-domain processing and conversion on the voltage sampling signal and the current sampling signal to obtain the frequency-domain voltage signal and the frequency-domain current signal.

[0095] The current sampling signal is obtained by synchronously sampling the excitation current signal according to a preset sampling frequency. In other words, the voltage sampling signal corresponds to the current sampling signal.

[0096] In this process, the quadrature digital lock-in amplifier algorithm is typically used to process and convert the voltage sampling signal and the current sampling signal from the time domain to the frequency domain.

[0097] S104. Based on the frequency domain voltage signal and frequency domain current signal, the electrochemical impedance spectrum is obtained.

[0098] Since the frequency of the excitation current signal corresponds one-to-one with the frequency Fre of the impedance to be measured in the electrochemical impedance spectroscopy, the preset sampling frequency... fs The first product of the frequency of the excitation current signal and a first preset value is used to set the preset sampling frequency. fs The frequency Fre corresponds to the impedance to be measured in the electrochemical impedance spectroscopy. Therefore, the data lengths of both the voltage and current sampling signals are relatively short, significantly reducing the computational load of electrochemical impedance spectroscopy. This saves storage capacity and computing power in the processing chip, making its computing performance controllable.

[0099] For example, the processing chip is usually a 3C chip. A 3C chip is a type of integrated circuit chip specifically designed for 3C products (i.e., computers, communication devices, and consumer electronics). The core function of a 3C chip is to realize the core functions of 3C products, such as computing, storage, signal processing, and communication connectivity; it is the "core brain" and "hardware foundation" for the normal operation of 3C products.

[0100] The electrochemical impedance spectroscopy (EIS) measurement method provided in this application involves applying an excitation current signal to the battery under test (BUT) to obtain the response voltage signal output by the BUT in response to the excitation current signal. The response voltage signal is then sampled according to a preset sampling frequency to obtain a voltage sampling signal. Simultaneously, the excitation current signal is sampled at the same preset sampling frequency to obtain a current sampling signal. These voltage and current sampling signals are then processed and converted from the time domain to the frequency domain to obtain frequency-domain voltage and current signals. Furthermore, the EIS is obtained based on these frequency-domain voltage and current signals. Since the frequency of the excitation current signal corresponds one-to-one with the frequency of the impedance to be measured in the EIS, and the preset sampling frequency is an integer multiple of the frequency of the excitation current signal, the preset sampling frequency corresponds to the frequency of the impedance to be measured in the EIS. Therefore, the data lengths of both the voltage and current sampling signals are relatively short, significantly reducing the computational load of the EIS. This saves storage capacity and computing power in the processing chip, making the computing performance of the processing chip controllable.

[0101] Based on the description of the above embodiments, the specific implementation method of the preset sampling frequency in S102 will be described in detail.

[0102] When the frequency Fre of the impedance under test is greater than or equal to the threshold frequency, the preset sampling frequency is the first product of the frequency of the excitation current signal and a first preset value N. In other words, when the frequency Fre of the impedance under test is relatively large, the preset sampling frequency is the preset sampling frequency with the smallest corresponding frequency value. When the frequency Fre of the impedance under test is less than the threshold frequency, the preset sampling frequency is the second product, which is the product of the first product and a third preset value m. In other words, when the frequency Fre of the impedance under test is relatively small, the preset sampling frequency is the preset sampling frequency with the largest corresponding frequency value.

[0103] For example, both the first preset value N and the third preset value m are integers greater than 1. Optionally, the first preset value N is an even integer greater than or equal to 16. For ease of explanation, the embodiments of this application will use a first preset value N of 16 as an example for detailed description.

[0104] Typically, when the frequency Fre of the impedance under test is high, the response voltage signal corresponding to the excitation current signal for q cycles is sampled using the preset sampling frequency with the lowest frequency value. Conversely, when the frequency Fre of the impedance under test is low, the response voltage signal corresponding to the excitation current signal for one cycle is sampled using the preset sampling frequency with the highest frequency value. This process ensures the accuracy of the voltage sampling signal acquisition time and guarantees sufficient voltage sampling signal acquisition. Consequently, the signal-to-noise ratio is maintained during the calculation of the electrochemical impedance spectroscopy.

[0105] In some examples, when the frequency Fre of the impedance under test is greater than or equal to the threshold frequency, the number of cycles of the excitation current signal is a second preset value q. When the frequency Fre of the impedance under test is less than the threshold frequency, the number of cycles of the excitation current signal is one.

[0106] The excitation current signal is a square wave current signal with a duty cycle of 50%. The second preset value q is an integer greater than or equal to 5.

[0107] The amplitude of the square wave current signal is typically set to 5-10% of the battery capacity. For example, the amplitude of the square wave current signal is 200mA. Another example is 50mA.

[0108] The threshold frequency is, for example, 1 Hz. For ease of explanation, the embodiments in this application are all described using a threshold frequency of 1 Hz as an example.

[0109] Specifically, when the frequency Fre of the impedance under test is greater than or equal to 1 Hz, the number of cycles of the excitation current signal is a second preset value q. That is, when the frequency Fre of the impedance under test is relatively high, an excitation current signal with the second preset value q cycles will be generated, such as... Figure 4 As shown, Figure 4 A schematic diagram of the excitation current signal in an electrochemical impedance spectroscopy measurement method provided in this application embodiment. Figure 1 The second preset value q is, for example, 5.

[0110] Specifically, when the frequency Fre of the impedance under test is less than 1 Hz, the excitation current signal has one cycle. That is, when the frequency Fre of the impedance under test is relatively low, a one-cycle excitation current signal will be generated, such as... Figure 5 As shown, Figure 5 A schematic diagram of the excitation current signal in an electrochemical impedance spectroscopy measurement method provided in this application embodiment. Figure 2 .

[0111] Among them, such as Figure 4 and Figure 5As shown, the voltage sampling signal consists of the initial voltage value V0 and the voltage value V. i The difference between them is ΔV. Where V0 is the voltage value at the last moment before the excitation current signal is applied, and V... i This represents the voltage value corresponding to the application of the excitation current signal.

[0112] in, Figure 4 and Figure 5 In this context, A represents the amplitude of the excitation current signal.

[0113] In cases where the frequency Fre of the impedance under test is low, the heat generated by the processing chip accumulates continuously with the application time of the excitation current signal as it generates multiple cycles. Therefore, in this embodiment, when the frequency Fre of the impedance under test is low, only one cycle of the excitation current signal is generated, which avoids the risk of overheating of the processing chip. Furthermore, it reduces the power consumption of the processing chip.

[0114] In the case where the frequency Fre of the impedance to be measured is large, the period of the excitation current signal is short. Therefore, in this embodiment of the application, when the frequency Fre of the impedance to be measured is large, the processing chip will not have the risk of overheating while generating the excitation current signal for the second preset value q cycles.

[0115] The processing chip is, for example, an analog front-end chip. Using the SINK mode of the analog front-end chip, if the frequency Fre of the impedance under test is low, the analog front-end chip will generate a one-cycle excitation current signal. If the frequency Fre of the impedance under test is high, the analog front-end chip will generate a second preset value of q cycles of excitation current signal.

[0116] Specifically, for the response voltage signal corresponding to the excitation current signal of a single cycle, the acquisition time of the first voltage sample signal in the voltage sampling signal is typically... The acquisition time corresponding to the last voltage sample signal in the voltage sampling signal is This avoids the voltage sampling signal acquisition time coinciding with the abrupt change in the excitation current signal.

[0117] Where N is the first preset value, and T is the period of the excitation current signal.

[0118] Reference Figure 6 , Figure 6 This is a schematic diagram of the voltage sampling signal structure in an electrochemical impedance spectroscopy measurement method provided in an embodiment of this application. Figure 6As shown, when the first preset value N is 16, the abrupt change time of the excitation current signal is T / 2, and the acquisition time corresponding to the first voltage sampling signal in the voltage sampling signal is T / 32. The acquisition times corresponding to the two voltage sampling signals closest to the abrupt change time in the voltage sampling signal are 15T / 32 and 17T / 32, respectively. The acquisition time corresponding to the last voltage sampling signal in the voltage sampling signal is 31T / 32.

[0119] Among them, such as Figure 6 As shown, the amplitude of the excitation current signal is usually preset. Therefore, even for different frequencies Fre of the impedance under test, the amplitude of the excitation current signal is [A, A, A, ..., A, 0, 0, ..., 0, 0]. Among them, for a single cycle of the excitation current signal, the amplitude of the first N / 2 excitation current signals is A, and the amplitude of the last N / 2 excitation current signals is 0.

[0120] in, Figure 6 In this context, 'a' represents the excitation current signal and 'b' represents the response voltage signal.

[0121] Based on the description of the above embodiments, the specific implementation method of performing time-domain to frequency-domain processing and conversion on the voltage sampling signal and the current sampling signal in S103 to obtain frequency-domain voltage signal and frequency-domain current signal will be described in detail.

[0122] Obtain in-phase and quadrature reference signals with the same frequency as the voltage sampling signal. Based on the in-phase and quadrature reference signals and the voltage sampling signal, obtain the frequency-domain voltage signal. Based on the in-phase and quadrature reference signals and the current sampling signal, obtain the frequency-domain current signal.

[0123] Since the excitation current signal is a square wave current signal, the excitation current signal (i.e., the square wave current signal) can be specifically represented by formula (2):

[0124] (2)

[0125] in, x(t) It is a square wave current signal. A The amplitude of the square wave current signal is denoted as . T The period of the square wave current signal.

[0126] Formula (2) is transformed using Fourier series. Thus, the square wave current signal can also be specifically represented by formula (3):

[0127] (3)

[0128] in, i(t) It is a square wave current signal. AThe amplitude of the square wave current signal is denoted as . φ I The phase of the square wave current signal. f 0 represents the frequency of the square wave current signal. n =1, 3, 5....

[0129] Among them, it can be found through formula (3) that the square wave current signal is composed of a DC current signal. A / 2 Fundamental frequency current signal sin2πf 0 t It is formed by the superposition of odd-order harmonics, and the harmonic amplitude gradually decreases as the harmonic order increases.

[0130] Based on the above description, let's assume that the fundamental frequency current signal in the excitation current signal can be specifically represented by formula (4):

[0131] (4)

[0132] in, I The fundamental frequency current signal in the excitation current signal. A I1 The amplitude of the fundamental frequency current signal (i.e. A I1 (The ratio of the amplitude of twice the square wave current signal to π). φ I1 The phase of the fundamental frequency current signal. f 01 The frequency of the fundamental frequency current signal is denoted as .

[0133] Among them, the phase of the base frequency current signal is equal to the phase of the square wave current signal, and the frequency of the base frequency current signal is equal to the frequency of the square wave current signal.

[0134] Correspondingly, the fundamental frequency voltage signal of the response voltage signal can be specifically represented by formula (5):

[0135] (5)

[0136] in, U The fundamental frequency voltage signal in response to the voltage signal, A U1 The amplitude of the fundamental frequency voltage signal in response to the voltage signal. φ U1 The phase of the fundamental frequency voltage signal in response to the voltage signal, f 02 The frequency of the fundamental voltage signal in response to the voltage signal.

[0137] Since the excitation current signal corresponds to the response voltage signal, the frequency of the response voltage signal is equal to the frequency of the fundamental frequency current signal.

[0138] Since the response voltage signal is sampled according to a preset sampling frequency, a voltage sampling signal is obtained. That is, the voltage sampling signal is obtained by discretizing the response voltage signal. Therefore, the fundamental frequency voltage signal in the voltage sampling signal can be specifically represented by formula (6):

[0139] (6)

[0140] in, u(k) This refers to the fundamental frequency voltage signal in the voltage sampling signal. A U2 This represents the amplitude of the fundamental frequency voltage signal in the voltage sampling signal. φ U2 This represents the phase of the fundamental frequency voltage signal in the voltage sampling signal. k =0, 1, 2..., M1-1, N M1 is the first preset value, and M1 is the data length of the voltage sampling signal.

[0141] Since the voltage sampling signal is obtained based on the response voltage signal, the amplitude of the fundamental frequency voltage signal in the voltage sampling signal is equal to the amplitude of the fundamental frequency voltage signal in the response voltage signal. The phase of the fundamental frequency voltage signal in the voltage sampling signal is also equal to the phase of the fundamental frequency voltage signal in the response voltage signal.

[0142] The preset sampling frequency can be specifically expressed by formula (7):

[0143] f s = N * f 0 (7)

[0144] in, f s To preset the sampling frequency, f 0 represents the frequency of the excitation current signal. N This is the first preset value.

[0145] Correspondingly, the fundamental frequency current signal in the current sampling signal can be specifically represented by formula (8):

[0146] (8)

[0147] in, i(k) This refers to the fundamental frequency current signal in the current sampling signal. A I2 The amplitude of the fundamental frequency current signal in the current sampling signal. φ I2 This represents the phase of the fundamental frequency current signal in the current sampling signal. k=0, 1, 2..., M2-1, N M1 is the first preset value, and M2 is the data length of the current sampling signal.

[0148] Since the current sampling signal is obtained by sampling the excitation current signal, the amplitude of the fundamental frequency current signal in the current sampling signal is equal to the amplitude of the fundamental frequency current signal in the excitation current signal. The phase of the fundamental frequency current signal in the current sampling signal is also equal to the phase of the fundamental frequency current signal in the excitation current signal.

[0149] Based on the description of the above embodiments, and in conjunction with Figure 7 The specific implementation method of obtaining the frequency domain voltage signal based on the in-phase reference signal, the quadrature reference signal and the voltage sampling signal is described in detail.

[0150] Reference Figure 7 , Figure 7 This is a schematic flowchart illustrating another electrochemical impedance spectroscopy measurement method provided in an embodiment of this application. Figure 7 As shown, the electrochemical impedance spectroscopy measurement method of this application may include the following steps:

[0151] S201. Obtain the fundamental frequency voltage signal from the voltage sampling signal.

[0152] S202. Based on the in-phase reference signal and the fundamental frequency voltage signal, obtain the first correlation parameter, and based on the quadrature reference signal and the fundamental frequency voltage signal, obtain the second correlation parameter.

[0153] The first correlation parameter characterizes the correlation between the in-phase reference signal and the fundamental frequency voltage signal. The second correlation parameter characterizes the correlation between the quadrature reference signal and the fundamental frequency voltage signal.

[0154] The first relevant parameter can be specifically represented by formula (9):

[0155] (9)

[0156] in, M1 The data length of the voltage sampling signal. R uyc1 As the first relevant parameter, This refers to the fundamental frequency voltage signal in the voltage sampling signal. For in-phase reference signal, k =0, 1, 2..., M1-1, A U2 This represents the amplitude of the fundamental frequency voltage signal in the voltage sampling signal. φ U2 This represents the phase of the fundamental frequency voltage signal in the voltage sampling signal. N This is the first preset value.

[0157] The second relevant parameter can be specifically represented by formula (10):

[0158] (10)

[0159] in, M1 The data length of the voltage sampling signal. R uys1 The second relevant parameter, The fundamental frequency voltage signal in the voltage sampling signal. For orthogonal reference signals, k =0, 1, 2..., M1-1, A U2 This represents the amplitude of the fundamental frequency voltage signal in the voltage sampling signal. φ U2 This represents the phase of the fundamental frequency voltage signal in the voltage sampling signal. N This is the first preset value.

[0160] Similarly, the harmonic voltage signals in the voltage sampling signal are obtained. Furthermore, based on the in-phase reference signal and the harmonic voltage signals, the third correlation parameter is obtained, and based on the quadrature reference signal and the harmonic voltage signals, the fourth correlation parameter is obtained.

[0161] The third correlation parameter characterizes the correlation between the in-phase reference signal and the harmonic voltage signal. The fourth correlation parameter characterizes the correlation between the quadrature reference signal and the harmonic voltage signal. Both the third and fourth correlation parameters are zero.

[0162] The third relevant parameter can be specifically represented by formula (11):

[0163] (11)

[0164] Among them, based on the orthogonality of trigonometric functions, since the trigonometric functions in formula (11) and trigonometric functions The different frequencies cause the integral result of their multiplication to be 0 (i.e., the third correlation parameter is 0).

[0165] in, M1 The data length of the voltage sampling signal. R uyc2 As the third relevant parameter, This refers to the harmonic voltage signal in the voltage sampling signal. For in-phase reference signal, k =0, 1, 2..., M1-1, n =3, 5, 7......., AU3 / n The amplitude of the harmonic voltage signal in the voltage sampling signal. φ U3 The phase of the harmonic voltage signal in the voltage sampling signal. N This is the first preset value.

[0166] The fourth relevant parameter can be specifically represented by formula (12):

[0167] (12)

[0168] Among them, based on the orthogonality of trigonometric functions, since the trigonometric functions in formula (12) and trigonometric functions The different frequencies cause the integral result of their multiplication to be 0 (i.e., the fourth correlation parameter is 0).

[0169] in, M1 The data length of the voltage sampling signal. R uys2 This is the fourth relevant parameter. This refers to the harmonic voltage signal in the voltage sampling signal. For orthogonal reference signals, k =0, 1, 2..., M1-1, n =3, 5, 7......., A U3 / n The amplitude of the harmonic voltage signal in the voltage sampling signal. φ U3 The phase of the harmonic voltage signal in the voltage sampling signal. N This is the first preset value.

[0170] Similarly, the DC voltage signal in the voltage sampling signal is obtained. Furthermore, based on the in-phase reference signal and the DC voltage signal, the fifth correlation parameter is obtained, and based on the quadrature reference signal and the DC voltage signal, the sixth correlation parameter is obtained.

[0171] The fifth correlation parameter characterizes the correlation between the in-phase reference signal and the DC voltage signal. The sixth correlation parameter characterizes the correlation between the quadrature reference signal and the DC voltage signal. Both the fifth and sixth correlation parameters are zero.

[0172] The fifth relevant parameter can be specifically represented by formula (13):

[0173] (13)

[0174] in, R uyc3 The fifth relevant parameter,A U4 / 2 This refers to the DC voltage signal in the voltage sampling signal. For in-phase reference signal, k =0, 1, 2..., M1-1, N This is the first preset value.

[0175] The sixth relevant parameter can be specifically represented by formula (14):

[0176] (14)

[0177] in, R uys3 The sixth relevant parameter, A U4 / 2 This refers to the DC voltage signal in the voltage sampling signal. For orthogonal reference signals, k =0, 1, 2..., M1-1, N This is the first preset value.

[0178] S203. Based on the first correlation parameter and the second correlation parameter, the frequency domain voltage signal is obtained.

[0179] Since the third, fourth, fifth, and sixth correlation parameters are all zero, the frequency domain voltage signal is simply the result of correlation operations between the fundamental frequency voltage signal of the response voltage signal and the in-phase reference signal and the quadrature reference signal, respectively. In other words, the frequency domain voltage signal is obtained by using the quadrature digital lock-in amplifier algorithm to perform a time-domain to frequency-domain transformation on the fundamental frequency voltage signal of the response voltage signal.

[0180] The amplitude of the frequency domain voltage signal can be calculated using formula (15) for the first and second correlation parameters.

[0181] (15)

[0182] in, A U5 The amplitude of the frequency domain voltage signal. R uyc1 As the first relevant parameter, R uys1 This is the second relevant parameter. The amplitude of the frequency domain voltage signal is equal to the amplitude of the fundamental frequency voltage signal in the voltage sampling signal.

[0183] Specifically, the phase of the frequency domain voltage signal can be calculated using formula (16) based on the first and second correlation parameters:

[0184] (16)

[0185] in, φ U4 The phase of the frequency domain voltage signal. R uyc1 As the first relevant parameter, R uys1 This is the second relevant parameter. The phase of the frequency domain voltage signal is equal to the phase of the fundamental frequency voltage signal in the voltage sampling signal.

[0186] Based on the description of the above embodiments, and in conjunction with Figure 8 The specific implementation method of obtaining the frequency domain current signal based on the in-phase reference signal, the quadrature reference signal and the current sampling signal is described in detail.

[0187] Reference Figure 8 , Figure 8 This is a schematic flowchart illustrating another electrochemical impedance spectroscopy measurement method provided in this application embodiment. Figure 8 As shown, the electrochemical impedance spectroscopy measurement method of this application may include the following steps:

[0188] S301. Obtain the fundamental frequency current signal from the current sampling signal.

[0189] S302. Based on the in-phase reference signal and the fundamental frequency current signal, the seventh correlation parameter is obtained, and based on the quadrature reference signal and the fundamental frequency current signal, the eighth correlation parameter is obtained.

[0190] The seventh correlation parameter is used to characterize the correlation between the in-phase reference signal and the fundamental frequency current signal, while the eighth correlation parameter is used to characterize the correlation between the quadrature reference signal and the fundamental frequency current signal.

[0191] The seventh relevant parameter can be specifically represented by formula (17):

[0192] (17)

[0193] in, M2 The data length of the current sampling signal. R iyc1 This is the seventh relevant parameter. This refers to the fundamental frequency current signal in the current sampling signal. For in-phase reference signal, k =0, 1, 2..., M2-1, A I2 The amplitude of the fundamental frequency current signal in the current sampling signal. φ I2 This represents the phase of the fundamental frequency current signal in the current sampling signal. N This is the first preset value.

[0194] The eighth relevant parameter can be specifically represented by formula (18):

[0195] (18)

[0196] in, M2 The data length of the current sampling signal. R iys1 This is the eighth relevant parameter. This refers to the fundamental frequency current signal in the current sampling signal. For orthogonal reference signals, k =0, 1, 2..., M2-1, A I2 The amplitude of the fundamental frequency current signal in the current sampling signal. φ I2 This represents the phase of the fundamental frequency current signal in the current sampling signal. N This is the first preset value.

[0197] Similarly, the harmonic current signal in the current sampling signal is obtained. Furthermore, the ninth correlation parameter is obtained based on the in-phase reference signal and the harmonic current signal, and the tenth correlation parameter is obtained based on the quadrature reference signal and the harmonic current signal.

[0198] The ninth correlation parameter characterizes the correlation between the in-phase reference signal and the harmonic current signal. The tenth correlation parameter characterizes the correlation between the quadrature reference signal and the harmonic current signal. Both the ninth and tenth correlation parameters are zero.

[0199] The ninth relevant parameter can be specifically represented by formula (19):

[0200] (19)

[0201] Among them, based on the orthogonality of trigonometric functions, since the trigonometric functions in formula (19) and trigonometric functions The frequencies are different, so the integral result of their multiplication is 0 (i.e., the ninth related parameter is 0).

[0202] in, M2 The data length of the current sampling signal. R iyc2 This is the ninth relevant parameter. This refers to the harmonic current signal in the current sampling signal. For in-phase reference signal, k =0, 1, 2..., M2-1, n =3, 5, 7......., AI3 / n The amplitude of the harmonic current signal in the current sampling signal. φ I3 This represents the phase of the harmonic current signal in the current sampling signal. N This is the first preset value.

[0203] The tenth relevant parameter can be specifically represented by formula (20):

[0204] (20)

[0205] Among them, based on the orthogonality of trigonometric functions, since the trigonometric functions in formula (20) and trigonometric functions The frequencies are different, so the integral result of their multiplication is 0 (i.e., the tenth related parameter is 0).

[0206] in, M2 The data length of the current sampling signal. R uys2 The tenth relevant parameter, This refers to the harmonic current signal in the current sampling signal. For orthogonal reference signals, k =0, 1, 2..., M2-1, A I3 / n The amplitude of the harmonic current signal in the current sampling signal. φ I3 This represents the phase of the harmonic current signal in the current sampling signal. N This is the first preset value.

[0207] Similarly, the DC current signal in the current sampling signal is obtained. Furthermore, based on the in-phase reference signal and the DC current signal, the eleventh correlation parameter is obtained, and based on the quadrature reference signal and the DC current signal, the twelfth correlation parameter is obtained.

[0208] The eleventh correlation parameter characterizes the correlation between the in-phase reference signal and the DC current signal. The twelfth correlation parameter characterizes the correlation between the quadrature reference signal and the DC current signal. Both the eleventh and twelfth correlation parameters are zero.

[0209] The eleventh relevant parameter can be specifically represented by formula (21):

[0210] (twenty one)

[0211] in, R iyc3 For the eleventh relevant parameter, AI4 / 2 This refers to the DC current signal in the current sampling signal. For in-phase reference signal, k =0, 1, 2..., M2-1, N This is the first preset value.

[0212] The twelfth relevant parameter can be specifically represented by formula (22):

[0213] (twenty two)

[0214] in, R iys3 This is the twelfth relevant parameter. A I4 / 2 This refers to the DC current signal in the current sampling signal. For orthogonal reference signals, k =0, 1, 2..., M2-1, N This is the first preset value.

[0215] S303. Based on the seventh and eighth related parameters, the frequency domain current signal is obtained.

[0216] Since the ninth, tenth, eleventh, and twelfth correlation parameters are all zero, the frequency-domain current signal is simply the result of correlation operations between the fundamental frequency current signal of the square wave current signal and the in-phase reference signal and the quadrature reference signal, respectively. In other words, the frequency-domain current signal is obtained by performing a time-domain to frequency-domain transformation on the fundamental frequency current signal of the square wave current signal using the quadrature digital lock-in amplifier algorithm.

[0217] The amplitude of the frequency domain current signal can be calculated using formula (23) for the seventh and eighth related parameters:

[0218] (twenty three)

[0219] in, A I5 The amplitude of the frequency domain current signal. R iyc1 This is the seventh relevant parameter. R iys1 This is the eighth relevant parameter. The amplitude of the frequency domain current signal is equal to the amplitude of the fundamental frequency current signal in the current sampling signal.

[0220] The phase of the frequency domain current signal can be calculated using formula (24) for the seventh and eighth related parameters:

[0221] (twenty four)

[0222] in, φ I4 The phase of the frequency domain current signal. R iyc1 This is the seventh relevant parameter. R iys1 This is the eighth relevant parameter. The phase of the frequency domain current signal is equal to the phase of the fundamental frequency current signal in the current sampling signal.

[0223] Based on the description of the above embodiments, and in conjunction with Figure 9 The specific implementation method of obtaining the electrochemical impedance spectrum based on the frequency domain voltage signal and the frequency domain current signal in S104 is described in detail.

[0224] Reference Figure 9 , Figure 9 This is a schematic flowchart illustrating another electrochemical impedance spectroscopy measurement method provided in this application embodiment. Figure 9 As shown, the electrochemical impedance spectroscopy measurement method of this application may include the following steps:

[0225] S401. Obtain the impedance data corresponding to the frequency of the impedance to be measured based on the frequency domain voltage signal and the frequency domain current signal.

[0226] The impedance data may include at least the impedance magnitude and the impedance phase.

[0227] The real part of the impedance and the imaginary part of the impedance can be determined based on the impedance magnitude and impedance phase.

[0228] In some examples, the ratio between the amplitude of the frequency-domain voltage signal and the amplitude of the frequency-domain current signal is determined as the impedance amplitude. The difference between the phase of the frequency-domain voltage signal and the phase of the frequency-domain current signal is determined as the impedance phase.

[0229] The impedance magnitude can be specifically expressed by formula (25):

[0230] (25)

[0231] Where Z is the impedance magnitude. A U5 The amplitude of the frequency domain voltage signal. A I5 This represents the amplitude of the frequency domain current signal.

[0232] The impedance phase can be specifically represented by formula (26):

[0233] (26)

[0234] in, φZ For impedance phase, φ U4 The phase of the frequency domain voltage signal. φ I4 The phase of the frequency domain current signal.

[0235] The real part of the impedance can be calculated using formula (27):

[0236] (27)

[0237] Where Z' is the real part of the impedance, and |Z| is the impedance magnitude. φ Z This is the impedance phase.

[0238] The imaginary part of the impedance can be calculated using formula (28):

[0239] Z''=|Z|sin φ Z (28)

[0240] Where Z'' is the imaginary part of the impedance, and |Z| is the impedance magnitude. φ Z This is the impedance phase.

[0241] This involves storing impedance data and the frequency of the corresponding impedance to be measured. The stored content may include: the frequency, impedance amplitude, impedance phase, real part, and imaginary part of the impedance to be measured corresponding to the impedance data.

[0242] The impedance data can be stored according to Table 1.

[0243] Table 1: Impedance Data Storage Table

[0244]

[0245] Where Fre is the frequency of the impedance to be measured corresponding to the impedance data, and |Z| is the impedance amplitude. φ Z Z' is the impedance phase, Z' is the real part of the impedance, and Z'' is the imaginary part of the impedance.

[0246] S402. Based on the impedance data and the frequency of the impedance to be measured, the electrochemical impedance spectrum is obtained.

[0247] The frequency of the impedance to be measured corresponds one-to-one with the impedance data.

[0248] Reference Figure 10 , Figure 10This is a schematic flowchart illustrating another electrochemical impedance spectroscopy (EIS) measurement method provided in this application embodiment. Based on the above embodiment, after step S104, the EIS measurement method may further include the following steps:

[0249] S105. Based on the impedance amplitude and impedance phase, determine the real part and imaginary part of the impedance corresponding to the frequency of the impedance to be measured.

[0250] S106. Verify the accuracy of the impedance data based on the real part of the impedance, the imaginary part of the impedance, the preset real part of the impedance, the preset imaginary part of the impedance, and the impedance amplitude.

[0251] The real and imaginary parts of the preset impedance were obtained by measurement using an electrochemical workstation.

[0252] The accuracy of the impedance data can be calculated using the following formula (29):

[0253] (29)

[0254] in, FitFun For the accuracy of impedance data, D The number of frequencies of the impedance to be measured in the electrochemical impedance spectroscopy. Z me (i)' For the first i The real part of the preset impedance corresponding to the frequency of the impedance to be measured. Z me (i)'' For the first i The imaginary part of the preset impedance corresponding to the frequency of the impedance to be measured. Z i ' Let be the real part of the impedance corresponding to the frequency of the i-th impedance to be measured. Z i '' For the first i The imaginary part of the impedance corresponding to the frequency of the impedance to be measured. |Zme(i)| For the first i The preset impedance amplitude corresponding to the frequency of the impedance to be measured.

[0255] Compared to the verification schemes for impedance data accuracy in related technologies, the embodiments of this application introduce a preset impedance amplitude into the verification of impedance data, making the verification of impedance data accuracy more reasonable.

[0256] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0257] The embodiments of this application can divide the electrochemical impedance spectroscopy measurement system into functional modules according to the above method examples. For example, each function can be divided into its own functional module, or two or more functions can be integrated into one processing unit. The integrated unit can be implemented in hardware or as a software functional module.

[0258] The module division in this embodiment is illustrative and represents only one logical functional division. In actual implementation, there may be other division methods.

[0259] Reference Figure 11 , Figure 11 A schematic diagram of an electrochemical impedance spectroscopy measurement system provided in an embodiment of this application. The measurement system 800 may include:

[0260] The excitation module 801 is used to apply an excitation current signal to the battery under test.

[0261] The excitation module 801 is, for example, a load. That is, the excitation current signal can be applied to the battery under test through the load.

[0262] The acquisition module 802 is used to acquire the response voltage signal output by the battery under test in response to the excitation current signal, and to sample the response voltage signal at a preset sampling frequency to obtain a voltage sampling signal, and to synchronously sample the excitation current signal at a preset sampling frequency to obtain a current sampling signal.

[0263] The frequency of the excitation current signal corresponds one-to-one with the frequency of the impedance to be measured in the electrochemical impedance spectrum, and the preset sampling frequency is an integer multiple of the frequency of the excitation current signal.

[0264] The acquisition module 802 can be implemented in hardware or as a software functional module; this application embodiment does not specifically limit its implementation. When the acquisition module 802 is implemented in hardware, it can be an analog-to-digital converter (ADC).

[0265] The conversion module 803 is used to process and convert the voltage sampling signal and the current sampling signal from the time domain to the frequency domain to obtain the frequency domain voltage signal and the frequency domain current signal.

[0266] The current sampling signal is obtained by synchronously sampling the excitation current signal according to a preset sampling frequency.

[0267] The conversion module 803 can be implemented in hardware or as a software functional module, and this application embodiment does not specifically limit it in this way.

[0268] The processing module 804 is used to obtain the electrochemical impedance spectrum based on the frequency domain voltage signal and the frequency domain current signal.

[0269] The computing module 804 can be implemented in hardware or as a software functional module, and this application embodiment does not specifically limit it in this way.

[0270] The electrochemical impedance spectroscopy (EIS) measurement system described above obtains the response voltage signal of the battery under test (BUT) in response to the excitation current signal by applying an excitation current signal. The response voltage signal is sampled at a preset sampling frequency to obtain a voltage sampling signal, and the excitation current signal is simultaneously sampled at the same preset sampling frequency to obtain a current sampling signal. These voltage and current sampling signals are then converted from the time domain to the frequency domain to obtain frequency-domain voltage and current signals. Finally, the EIS is obtained based on these frequency-domain voltage and current signals. Since the frequency of the excitation current signal corresponds one-to-one with the frequency of the impedance to be measured in the EIS, and the preset sampling frequency is an integer multiple of the excitation current signal frequency, the preset sampling frequency corresponds to the frequency of the impedance to be measured in the EIS. Therefore, the data lengths of both the voltage and current sampling signals are relatively short, significantly reducing the computational load of the EIS. This saves storage capacity and computing power in the processing chip, making the processing chip's computing performance controllable.

[0271] For example, an embodiment of this application provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the above-described method for measuring electrochemical impedance spectroscopy.

[0272] For example, this application provides a computer-readable storage medium storing a computer program, which is executed by a processor to measure the electrochemical impedance spectroscopy method of the embodiment.

[0273] For example, this application provides a computer program product, including: a computer program stored in a computer-readable storage medium, at least one processor of an electronic device can read the computer program from the computer-readable storage medium, and the at least one processor executes the computer program to enable the electronic device to implement the electrochemical impedance spectroscopy measurement method in the foregoing embodiments.

[0274] In this application, the electronic device, computer-readable storage medium, and computer program product provided in the embodiments are all used to execute the corresponding methods provided above. Therefore, the beneficial effects they can achieve can be referred to the beneficial effects in the corresponding methods provided above, and will not be repeated here.

[0275] Finally, it should be noted that the above embodiments are merely specific implementations of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for measuring electrochemical impedance spectroscopy, characterized in that, The measurement method includes: An excitation current signal is applied to the battery under test; wherein the excitation current signal is a square wave current signal, the duty cycle of the square wave current signal is 50%, and the amplitude of the excitation current signal is 5-10% of the capacity of the battery under test; The method involves acquiring the response voltage signal output by the battery under test in response to the excitation current signal, sampling the response voltage signal at a preset sampling frequency to obtain a voltage sampling signal, and synchronously sampling the excitation current signal at the same preset sampling frequency to obtain a current sampling signal. The frequency of the excitation current signal corresponds one-to-one with the frequency of the impedance to be measured in the electrochemical impedance spectrum of the battery under test, and the preset sampling frequency is an integer multiple of the frequency of the excitation current signal. The acquisition time of the voltage sampling signal avoids abrupt changes in the excitation current signal, and the first acquisition time of the voltage sampling signal is... The last acquisition time of the voltage sampling signal is Where N is a first preset value, and T is the period of the excitation current signal; The voltage sampling signal and the current sampling signal are processed and converted from the time domain to the frequency domain to obtain the frequency domain voltage signal and the frequency domain current signal; The electrochemical impedance spectrum is obtained based on the frequency domain voltage signal and the frequency domain current signal.

2. The measurement method according to claim 1, characterized in that, When the frequency of the impedance to be measured is greater than or equal to the threshold frequency, the number of cycles of the excitation current signal is a second preset value, which is an integer greater than or equal to 5; when the frequency of the impedance to be measured is less than the threshold frequency, the number of cycles of the excitation current signal is one.

3. The measurement method according to claim 2, characterized in that, When the frequency of the impedance to be measured is greater than or equal to the threshold frequency, the preset sampling frequency is the first product result of the frequency of the excitation current signal multiplied by the first preset value; when the frequency of the impedance to be measured is less than the threshold frequency, the preset sampling frequency is the second product result, which is the product result of the first product result and the third preset value, where the first preset value and the third preset value are both integers greater than 1.

4. The measurement method according to claim 2, characterized in that, The voltage and current sampling signals are processed and converted from the time domain to the frequency domain to obtain frequency domain voltage and frequency domain current signals, including: Acquire an in-phase reference signal and a quadrature reference signal with the same frequency as the voltage sampling signal; The frequency domain voltage signal is obtained based on the in-phase reference signal, the quadrature reference signal, and the voltage sampling signal; The frequency domain current signal is obtained based on the in-phase reference signal, the quadrature reference signal, and the current sampling signal.

5. The measurement method according to claim 4, characterized in that, The step of obtaining the frequency domain voltage signal based on the in-phase reference signal, the quadrature reference signal, and the voltage sampling signal includes: Obtain the fundamental frequency voltage signal from the voltage sampling signal; A first correlation parameter is obtained based on the in-phase reference signal and the fundamental frequency voltage signal, and a second correlation parameter is obtained based on the quadrature reference signal and the fundamental frequency voltage signal. The first correlation parameter is used to characterize the correlation between the in-phase reference signal and the fundamental frequency voltage signal, and the second correlation parameter is used to characterize the correlation between the quadrature reference signal and the fundamental frequency voltage signal. The frequency domain voltage signal is obtained based on the first relevant parameter and the second relevant parameter.

6. The measurement method according to claim 5, characterized in that, The frequency domain voltage signal is obtained based on the first correlation parameter and the second correlation parameter, specifically according to the following formula: in, A U5 The amplitude of the frequency domain voltage signal. R uyc1 For the first relevant parameter, R uys1 For the second relevant parameter, The phase of the frequency domain voltage signal is denoted as .

7. The measurement method according to claim 4, characterized in that, The step of obtaining the frequency domain current signal based on the in-phase reference signal, the quadrature reference signal, and the current sampling signal includes: Obtain the fundamental frequency current signal from the current sampling signal; A seventh correlation parameter is obtained based on the in-phase reference signal and the fundamental frequency current signal, and an eighth correlation parameter is obtained based on the quadrature reference signal and the fundamental frequency current signal. The seventh correlation parameter is used to characterize the correlation between the in-phase reference signal and the fundamental frequency current signal, and the eighth correlation parameter is used to characterize the correlation between the quadrature reference signal and the fundamental frequency current signal. The frequency domain current signal is obtained based on the seventh and eighth related parameters.

8. The measurement method according to claim 7, characterized in that, The frequency domain current signal is obtained based on the seventh and eighth related parameters, specifically according to the following formula: in, A I5 The amplitude of the frequency domain current signal is given. R iyc1 For the seventh relevant parameter, R iys1 For the eighth relevant parameter, φ I4 The phase of the frequency domain current signal is given.

9. The measurement method according to any one of claims 1-8, characterized in that, The step of obtaining the electrochemical impedance spectrum based on the frequency domain voltage signal and the frequency domain current signal includes: Based on the frequency domain voltage signal and the frequency domain current signal, impedance data corresponding to the frequency of the impedance to be measured is obtained; wherein, the impedance data includes at least the impedance amplitude and the impedance phase; The electrochemical impedance spectrum is obtained based on the impedance data and the frequency of the impedance to be measured.

10. The measurement method according to claim 9, characterized in that, The step of obtaining the impedance data corresponding to the frequency of the impedance to be measured based on the frequency domain voltage signal and the frequency domain current signal includes: The ratio between the amplitude of the frequency domain voltage signal and the amplitude of the frequency domain current signal is determined as the impedance amplitude. The difference between the phase of the frequency domain voltage signal and the phase of the frequency domain current signal is determined as the impedance phase.

11. The measurement method according to claim 9, characterized in that, The measurement method further includes: Based on the impedance amplitude and the impedance phase, determine the real part and imaginary part of the impedance corresponding to the frequency of the impedance to be measured, respectively; The accuracy of the impedance data is verified based on the real part of the impedance, the imaginary part of the impedance, the preset real part of the impedance, the preset imaginary part of the impedance, and the preset impedance amplitude.

12. A measurement system for electrochemical impedance spectroscopy, characterized in that, The measurement system used in the electrochemical impedance spectroscopy measurement method according to any one of claims 1-11 comprises: The excitation module is used to apply an excitation current signal to the battery under test. The acquisition module is used to acquire the response voltage signal output by the battery under test in response to the excitation current signal, and to sample the response voltage signal at a preset sampling frequency to obtain a voltage sampling signal, and to synchronously sample the excitation current signal at the preset sampling frequency to obtain a current sampling signal; wherein, the frequency of the excitation current signal corresponds one-to-one with the frequency of the impedance to be measured in the electrochemical impedance spectrum of the battery under test, and the preset sampling frequency is an integer multiple of the frequency of the excitation current signal; The conversion module is used to perform time-domain to frequency-domain processing and conversion on the voltage sampling signal and the current sampling signal to obtain a frequency-domain voltage signal and a frequency-domain current signal; The processing module is used to obtain the electrochemical impedance spectrum based on the frequency domain voltage signal and the frequency domain current signal.

13. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 11.

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