Electrode slurry evaluation method and system based on DRT analysis, and memory

Abstract

The invention relates to the technical field of electrode slurry production, in particular to an electrode slurry evaluation method and system based on DRT analysis and a storage.The method comprises the steps that alternating current impedance testing is conducted on slurry to be tested to obtain electrochemical impedance data; performing time relaxation treatment on the electrochemical impedance data to obtain a DRT map; extracting target impedance data according to the DRT atlas and the fractional order model of the to-be-detected slurry; the target impedance data is the conductive path impedance of the adhesive in the to-be-detected slurry. Aiming at the problem that the conductivity of each component of the slurry is difficult to effectively measure in the prior art, a DRT analysis method is introduced in the analysis process of the slurry, alternating current impedance test data of the slurry is analyzed, so that the resistance and capacitance distribution conditions of the slurry under different frequencies are obtained, finally key features are extracted from an identification result, and the accuracy of the identification result is improved. The method is suitable for screening of an electrode slurry formula in the battery preparation process and determination of a process scheme in the process preparation process.

Description

Technical Field

[0001] The present invention relates to the technical field of electrode slurry production, and in particular to an electrode slurry evaluation method, system and memory based on DRT analysis. Background Art

[0002] Positive electrode slurry is a raw material widely used in battery production, primarily composed of active materials, conductive agents, binders, and solvents. Taking the positive electrode portion of a lithium-ion battery as an example, the positive electrode is typically formed by coating the current collector with the positive electrode slurry and then baking it to form a complete electrode structure. Therefore, the various performance indicators of the electrode slurry directly affect the performance of the battery cell and the resulting assembled battery. Taking this into account, the conductive properties of the slurry are often pre-measured during the slurry composition design process.

[0003] For example, Chinese patent CN202411210348.3 discloses a conductive slurry resistivity test device, including a constant current source, a blower, and a test box arranged under the blower. A sample table is placed in the center of the bottom surface of the test box, a sample slot is provided on the upper surface of the sample table, a scraper is placed on the sample table, and a four-probe test pen is connected to the top of the test box. The conductive slurry is placed in the sample slot, and then the blower is turned on to dry the conductive slurry. After drying the conductive slurry, the blower is turned off, and then the dried conductive slurry is scraped flat with a scraper. The four-probe test pen is placed in the center of the sample slot to test the data. This method is carried out by dispersing and evenly drying the conductive slurry and then scraping it flat. The four-probe test pen is used to test the value, and the resistivity of the conductive slurry is calculated based on the measured value. The thickness of the coating of the slurry is determined when the conductive slurry testing device is applied to the scraping film, and the test influencing factors are reduced. The four-probe test pen tests and compares four sets of data to make the data more stable.

[0004] For example, Chinese patent CN202111619882.6 discloses a method for testing the conductivity of lithium-ion battery conductive paste, including the following steps: S1, preparing calcium carbonate, PVDF, and conductive paste with a solvent in a ratio of 94-96:3-5:1 to form a mixed slurry; S2, evenly coating the evenly mixed mixed slurry on a PET film; S3, drying the PET film coated with the mixed slurry, slicing it and testing the resistivity; it solves the problems of large resistivity measurement fluctuations, low resistivity value accuracy and high cost in the prior art.

[0005] However, during the actual implementation process, the inventors found that in this type of technical solution, the slurry after coating is usually tested, and there is a lack of testing process for the slurry itself. This makes it difficult to effectively evaluate the actual conductive performance of each component in the slurry during the actual testing process. Summary of the Invention

[0006] In view of the above problems existing in the prior art, a method for evaluating electrode slurry based on DRT (Distribution of Relaxation Times) analysis is provided.

[0007] In another aspect, a memory for implementing the electrode slurry evaluation method is also provided;

[0008] On the other hand, an evaluation system for implementing the electrode slurry evaluation method is also provided.

[0009] The specific technical solutions are as follows:

[0010] A method for evaluating electrode slurry based on DRT analysis, comprising:

[0011] Step S1: performing an AC impedance test on the slurry to be tested to obtain electrochemical impedance data;

[0012] Step S2: performing time relaxation processing on the electrochemical impedance spectroscopy data to obtain a DRT spectrum;

[0013] Step S3: extracting target impedance data according to the DRT spectrum and the fractional order model of the slurry to be tested;

[0014] The target impedance data is the impedance of the conductive path of the binder in the slurry to be tested;

[0015] The target impedance data is used to determine the conductive properties of the slurry to be tested.

[0016] On the other hand, the step S1 includes:

[0017] Step S11: setting the sampling frequency range and sampling number for the slurry to be tested;

[0018] Step S12: connecting the slurry to be tested to an excitation device and a sampling device respectively;

[0019] Step S13: applying a constant voltage AC signal to the slurry to be tested by using the excitation device, and collecting an impedance response signal of the slurry to be tested by using the sampling device;

[0020] Step S14: drawing an impedance Nyquist plot according to the impedance response signal as the electrochemical impedance data;

[0021] In the impedance Nyquist diagram, the real part of the impedance response signal is the horizontal axis, and the negative imaginary part is the vertical axis.

[0022] On the other hand, the step S2 includes:

[0023] Step S21: constructing an impedance relaxation distribution function according to the electrochemical impedance data;

[0024] Step S22: extracting a relaxation distribution interval of the impedance relaxation distribution function according to a preset frequency range;

[0025] Step S23: drawing the DRT spectrum according to the relaxation distribution interval.

[0026] On the other hand, in step S21, the relaxation distribution function includes:

[0027]

[0028] Where Z(ω) is the total impedance, G(τ) is the relaxation distribution function, f is the frequency, i is the imaginary unit, ω is the angular frequency, and τ is the relaxation time.

[0029] On the other hand, step S3 includes:

[0030] Step S31: extracting multiple characteristic peaks from the DRT spectrum;

[0031] Step S32: mapping the characteristic peaks to multiple impedance parts in the fractional-order model respectively;

[0032] Step S33: selecting the characteristic peak corresponding to the impedance of the conductive path of the adhesive, and calculating the peak area to obtain the target impedance data.

[0033] On the other hand, in step S3, the target impedance data calculation process includes:

[0034]

[0035] Where Z DRT is the target impedance data, τ is the relaxation time constant, G(τ) is the relaxation distribution function, f is the frequency, R ∞ is the ohmic impedance of the slurry to be tested.

[0036] On the other hand, before executing step S1, the method further includes:

[0037] Step S01: preparing multiple groups of slurries to be tested using different recipes;

[0038] After executing step S3, the method further includes:

[0039] Step S4: comparing the slurry to be tested according to the target impedance data to determine a target formulation.

[0040] On the other hand, the DRT map includes the contact main material RC circuit, the adhesive conductive path RC circuit, the conductive agent RC circuit and the Warburg impedance.

[0041] A memory includes computer instructions, and when a computer device executes the computer instructions, the above-mentioned electrode slurry evaluation method is performed.

[0042] An evaluation system for implementing the above-mentioned electrode slurry evaluation method;

[0043] The evaluation system comprises:

[0044] A measuring module, wherein the measuring module performs an AC impedance test on the slurry to be tested to obtain electrochemical impedance data;

[0045] A spectrum generation module, the spectrum generation module is connected to the measurement module;

[0046] The spectrum generating module performs time relaxation processing on the electrochemical impedance spectroscopy data to obtain a DRT spectrum;

[0047] An impedance data generating module, the impedance data generating module being connected to the graph generating module;

[0048] The impedance data generation module extracts target impedance data according to the DRT spectrum and the fractional order model of the slurry to be tested;

[0049] The target impedance data is the impedance of the conductive path of the binder in the slurry to be tested;

[0050] The target impedance data is used to determine the conductive properties of the slurry to be tested.

[0051] The above technical solution has the following advantages or beneficial effects:

[0052] In response to the problem that the evaluation methods in the existing technology are difficult to effectively measure the conductivity of each component of the slurry itself, this solution introduces the DRT analysis method in the slurry analysis process. The AC impedance test data of the slurry is analyzed by the DRT analysis method to obtain the resistance and capacitance distribution of the slurry at different frequencies. Finally, the key features are extracted from the identification results to realize the process of model-free slurry conductivity diagnosis. It is suitable for the screening of electrode slurry formulas in the battery preparation process and the determination of process plans in the process preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The embodiments of the present invention will be described more fully with reference to the accompanying drawings, which are provided for illustration and description only and are not intended to limit the scope of the present invention.

[0054] Figure 1 is an overall schematic diagram of an embodiment of the present invention;

[0055] Figure 2 This is a schematic diagram of step S1 of an embodiment of the present invention;

[0056] Figure 3 This is a schematic diagram of step S2 of an embodiment of the present invention;

[0057] Figure 4 This is a schematic diagram of step S3 of an embodiment of the present invention;

[0058] Figure 5 This is a schematic diagram of step S01 in an embodiment of the present invention;

[0059] Figure 6 A schematic diagram of a system according to an embodiment of the present invention;

[0060] Figure 7 Schematic diagram of a measurement module according to an embodiment of the present invention;

[0061] Figure 8 This is a schematic diagram of a graph generation module according to an embodiment of the present invention;

[0062] Figure 9 Schematic diagram of an impedance data generation module according to an embodiment of the present invention. DETAILED DESCRIPTION

[0063] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0064] Some of the blocks shown in the accompanying drawings are functional entities that do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0065] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0066] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0067] The present invention comprises:

[0068] A method for evaluating electrode slurry based on DRT analysis, such as Figure 1 Shown, including:

[0069] Step S1: performing an AC impedance test on the slurry to be tested to obtain electrochemical impedance data;

[0070] Step S2: performing time relaxation processing on the electrochemical impedance spectroscopy data to obtain a DRT spectrum;

[0071] Step S3: extracting target impedance data according to the DRT spectrum and the fractional order model of the slurry to be tested;

[0072] The target impedance data is the impedance of the conductive path of the binder in the slurry to be tested;

[0073] The target impedance data is used to determine the conductive properties of the slurry to be tested.

[0074] Specifically, in response to the problem that the evaluation methods in the existing technology are difficult to effectively measure the conductivity of each component of the slurry itself, in this embodiment, the DRT analysis method is introduced in the analysis process of the slurry. The AC impedance test data of the slurry is analyzed by the DRT analysis method to obtain the resistance and capacitance distribution of the battery at different frequencies. Finally, the key features are extracted from the identification results to realize the process of model-free slurry conductivity diagnosis, which is suitable for the screening of electrode slurry formulas in the battery preparation process and the determination of process plans in the process preparation process.

[0075] Specifically, the slurry to be tested mainly refers to the related materials used to prepare battery electrodes, which are usually composed of active materials, conductive agents, binders and solvents, and are in a fluid or semi-fluid state. It can be placed in a specific container and connected to the corresponding electrodes and probes for AC impedance testing, including applying AC excitation signals and collecting impedance response signals.

[0076] Some existing technologies directly use this method to measure the impedance of the slurry, but it cannot actually determine the dispersion of the various components in the slurry, the conductivity of the slurry, or the stability of the slurry. To address this issue, this example first introduces AC impedance testing to collect electrochemical impedance data of the slurry.

[0077] Subsequently, the electrochemical impedance spectroscopy data was subjected to time relaxation processing to obtain a DRT spectrum, thereby measuring the resistance and capacitance distribution of each component in the electrode slurry at different frequencies.

[0078] Specifically, the measurement process of electrochemical impedance data is carried out when the electrochemical cell is in an open circuit state or under certain DC polarization conditions. By applying a small-amplitude sinusoidal AC excitation signal, the AC impedance of the electrochemical system is analyzed as the frequency changes. This method is called frequency-domain impedance analysis.

[0079] On this basis, by fitting and separating typical time constants, known as relaxation times, it is possible to simulate the time required for electrochemical system variables to transition from a transient state to a near-steady state under external perturbations. During relaxation time analysis, each characteristic peak of fluctuation corresponds to a kinetic process in the electrochemical system, and the time constant corresponding to that peak represents the response time of that kinetic process in the electrochemical system.

[0080] When the above analysis process is applied to the electrochemical impedance spectroscopy data analysis of the slurry, each reaction kinetic process corresponds to the impedance characteristics of each component in the slurry. Taking the fractional-order model of electrode slurry as an example, analysis based on this model can determine that there are four main reaction kinetic processes in the chemical system corresponding to this model. Arranged from short to long in terms of the response time of each process, they are the contact main material RC circuit in the slurry, the binder conductive path RC circuit, the conductive agent RC circuit, and the Warburg impedance. These four processes will appear as four characteristic peaks in the spectrum obtained by DRT analysis.

[0081] In order to achieve better screening of slurry conductivity, the binder conductive path impedance was selected as the main evaluation criterion in this embodiment, thereby achieving effective evaluation of the conductive performance in the slurry state.

[0082] In one embodiment, Figure 2 As shown, step S1 includes:

[0083] Step S11: setting the sampling frequency range and sampling number for the slurry to be tested;

[0084] Step S12: Connect the slurry to be tested to the excitation device and the sampling device respectively;

[0085] Step S13: applying a constant voltage AC signal to the slurry to be tested using an excitation device, and collecting an impedance response signal of the slurry to be tested using a sampling device;

[0086] Step S14: drawing an impedance Nyquist plot as electrochemical impedance data according to the impedance response signal;

[0087] In the impedance Nyquist plot, the real part of the impedance response signal is on the horizontal axis, and the negative imaginary part is on the vertical axis.

[0088] Specifically, in order to achieve the plus sign collection effect of electrochemical impedance data, in this embodiment, the sampling frequency range and sampling number of the sampling device are first set respectively, and then the slurry to be tested is connected to the excitation device and the sampling device respectively.

[0089] A typical test system is given here, which includes an insulated water tank for containing electrode slurry, an excitation device, such as a constant voltage AC power supply, and a sampling device, such as an impedance analyzer, an electrochemical workstation or other equivalent equipment.

[0090] The excitation device is used to generate a corresponding excitation signal according to the set parameters, and directly contact the electrode slurry in the water tank through the electrode to form a loop, thereby inputting a constant voltage AC signal into the slurry. At the same time, the sampling device connects the slurry through the probe to obtain the impedance response signal.

[0091] In one embodiment, the amplitude of the constant voltage AC signal is 40 mV, and the frequency is adjusted sequentially according to the set parameter range.

[0092] When the slurry receives the excitation signal, the sampling device performs bandpass processing on the impedance response signal according to the preset sampling frequency range, and then samples it according to the set sampling number to form an impedance response signal. Subsequently, the impedance Nyquist plot is drawn with the real part of the impedance as the horizontal axis and the negative imaginary part as the vertical axis as the electrochemical impedance data output.

[0093] In one embodiment, Figure 3 As shown, step S2 includes:

[0094] Step S21: constructing an impedance relaxation distribution function according to the electrochemical impedance data;

[0095] Step S22: extracting a relaxation distribution interval from the impedance relaxation distribution function according to a preset frequency range;

[0096] Step S23: Draw a DRT spectrum according to the relaxation distribution interval.

[0097] Specifically, in order to realize the construction of the DRT spectrum, in this embodiment, the electrochemical impedance data is first analyzed on the time scale, and the impedance relaxation distribution function corresponding to the electrochemical impedance data is constructed in combination with the relaxation distribution function. Subsequently, the impedance relaxation distribution function is extracted according to the frequency range to be analyzed subsequently, and the relaxation distribution range in the frequency range to be analyzed is obtained. Finally, the DRT spectrum is drawn according to the relaxation distribution range, thereby realizing effective characterization of the resistance and capacitance distribution of each component in the electrode slurry at different frequencies.

[0098] The frequency range is the frequency range of the response signal corresponding to the small-amplitude sinusoidal AC signal selected during the electrochemical impedance test in the electrochemical system. By intercepting this frequency range, other irrelevant signals in the overall test process, such as noise signals, can be eliminated.

[0099] In one embodiment, in step S21, the impedance relaxation distribution function includes:

[0100]

[0101] Where Z(ω) is the total impedance, G(τ) is the relaxation distribution function, f is the frequency, i is the imaginary unit, ω is the angular frequency, and τ is the relaxation time.

[0102] Specifically, G(τ) is the relaxation distribution function, τ is the relaxation time, which describes the time scale for a dynamic process in the system (such as ion diffusion and charge transfer) to recover from a non-equilibrium state to an equilibrium state. The frequency domain and time domain are connected by associating τ = 1 / (2πf) with the frequency f, so it corresponds to the time of the dynamic process. γ(τ) is used to reflect the contribution of the polarization process corresponding to different relaxation times in the electrochemical system. Because the frequency in the electrochemical impedance is counted by 10 times, G(τ) = τG(τ), τ and γ(τ) correspond to the horizontal and vertical axes of the DRT spectrum, respectively. f is the frequency of the response signal. iωτ is used in the impedance formula to describe the phase relationship under the AC signal, reflecting the dynamic response characteristics of the system, and involves complex number operations to process the frequency characteristics of the impedance. The combination of the above formulas can achieve effective characterization of electrochemical impedance data on a time scale.

[0103] In one embodiment, Figure 4 As shown, step S3 includes:

[0104] Step S31: extracting multiple characteristic peaks from the DRT spectrum;

[0105] Step S32: mapping the characteristic peaks to multiple impedance parts in the fractional-order model respectively;

[0106] Step S33: Select a characteristic peak corresponding to the impedance of the conductive path of the adhesive, and calculate the peak area to obtain target impedance data.

[0107] Specifically, after constructing the DRT spectrum, in order to effectively extract the target impedance data, multiple characteristic peaks are first extracted from the DRT spectrum.

[0108] Specifically, according to the fractional-order model of electrode slurry, the electrode slurry can be equivalent to the ohmic internal resistance, the parallel link of resistor-constant phase element, and the Warburg impedance;

[0109] Among them, the parallel circuit composed of the resistor-constant phase element is composed of the contact main material RC circuit, the adhesive conductive path RC circuit and the conductive agent RC circuit. According to the above analysis process, it can be seen that when a sinusoidal AC signal is applied to the electrode slurry, the above parallel circuit will first produce a response signal from the contact main material RC circuit, then the adhesive conductive path RC circuit, then the conductive agent RC circuit, and finally the Warburg impedance diffusion process, depending on the length of the response time.

[0110] In the DRT spectrum, multiple characteristic peaks can be extracted according to the amplitude change. This step can be performed by amplitude or derivative. Subsequently, the characteristic peak corresponding to the impedance of the adhesive conductive path is selected according to the response time.

[0111] The selection process can be to read the peak values ​​on the DRT spectrum in sequence according to the arrangement order determined above, and map them with the various parts of the aforementioned impedance model in the order of selection to establish a corresponding relationship. Among them, when the second characteristic peak is read, the corresponding characteristic peak is the characteristic peak corresponding to the impedance of the conductive path of the adhesive, and the target impedance data can be obtained by calculating the peak area.

[0112] In other embodiments, the DRT spectrum may be read out according to the pre-measured adhesive conductive path impedance, which usually has a corresponding relaxation time distribution, so as to extract the corresponding characteristic peak and establish a corresponding relationship between the characteristic peak and the adhesive conductive path impedance.

[0113] In one embodiment, in step S3, the target impedance data calculation process includes:

[0114]

[0115] Where Z DRT is the target impedance data, τ is the relaxation time constant, G(τ) is the relaxation distribution function, f is the frequency, R ∞ is the ohmic impedance of the slurry to be tested.

[0116] In one embodiment, Figure 5 As shown, before executing step S1, the method further includes:

[0117] Step S01: preparing multiple groups of slurries to be tested using different recipes;

[0118] After executing step S3, the method further includes:

[0119] Step S4: comparing the slurry to be tested according to the target impedance data to determine the target formulation.

[0120] Specifically, the above-mentioned evaluation method can be used in the screening process of electrode slurries. In the electrode slurry formula, the main material, binder, conductive agent, dispersant, and functional additive are mixed with a solvent in a ratio of 50-100%, 0-20%, 0-20%, 0-10%, and 0-10%, respectively, but not limited to this ratio range, to form a mixed slurry, and the total ratio is 100.

[0121] After designing the corresponding formula according to the assumed requirements, the above-mentioned evaluation method is used to obtain multiple sets of target impedance data. Then, the slurries to be tested are compared according to the target impedance data to determine the slurry to be tested with the best conductive performance, and its formula is output as the target formula.

[0122] An evaluation system for implementing the above-mentioned electrode slurry evaluation method;

[0123] like Figure 6 As shown, the evaluation system includes:

[0124] Measuring module 1, measuring module 1 performs AC impedance test on the slurry to be tested to obtain electrochemical impedance data;

[0125] A spectrum generating module 2, the spectrum generating module 2 is connected to the measuring module 1;

[0126] The spectrum generating module 2 performs time relaxation processing on the electrochemical impedance spectroscopy data to obtain a DRT spectrum;

[0127] Impedance data generating module 3, impedance data generating module 3 is connected to the spectrum generating module 2;

[0128] The impedance data generation module 3 extracts the target impedance data according to the DRT spectrum and the fractional order model of the slurry to be tested;

[0129] The target impedance data is the impedance of the conductive path of the binder in the slurry to be tested;

[0130] The target impedance data is used to determine the conductive properties of the slurry to be tested.

[0131] Specifically, in response to the problem that the evaluation methods in the existing technology are difficult to effectively measure the conductivity of each component of the slurry itself, in this embodiment, the DRT analysis method is introduced in the analysis process of the slurry. First, the electrochemical impedance data of the slurry is obtained by the measurement module 1, and then the spectrum generation module 2 analyzes the electrochemical impedance data of the slurry through the DRT analysis method to obtain the resistance and capacitance distribution of the battery at different frequencies. Finally, the impedance data generation module 3 extracts key features from the identification results to realize the process of model-free slurry conductivity diagnosis, which is suitable for the screening of electrode slurry formulas in the battery preparation process and the determination of process plans in the process preparation process.

[0132] In one embodiment, Figure 7 As shown, the measurement module 1 includes:

[0133] Setting module 11, setting module 11 sets the sampling frequency range and sampling number for the slurry to be tested;

[0134] Access module 12, access module 12 is connected to setting module 11;

[0135] The access module 12 connects the slurry to be tested to the excitation device and the sampling device respectively;

[0136] Test module 13, test module 13 is connected to access module 12

[0137] The test module 13 uses an excitation device to apply a constant voltage AC signal to the slurry to be tested, and uses a sampling device to collect the impedance response signal of the slurry to be tested;

[0138] A Nyquist diagram generating module 14 , wherein the Nyquist diagram generating module 14 is connected to the testing module 13 ;

[0139] The Nyquist plot generating module 14 draws an impedance Nyquist plot as electrochemical impedance data according to the impedance response signal;

[0140] In the impedance Nyquist plot, the real part of the impedance response signal is on the horizontal axis, and the negative imaginary part is on the vertical axis.

[0141] Specifically, to achieve the plus sign collection effect of electrochemical impedance data, in this embodiment, the setting module 11 first sets the sampling frequency range and sampling number of the sampling device respectively, and then the connecting module 12 connects the slurry to be tested to the excitation device and the sampling device respectively.

[0142] A typical test system is given here, which includes an insulated water tank for containing electrode slurry, an excitation device, such as a constant voltage AC power supply, and a sampling device, such as an impedance analyzer, an electrochemical workstation or other equivalent equipment.

[0143] The test module 13 controls the excitation device to generate a corresponding excitation signal according to the set parameters, and directly contacts the electrode slurry in the water tank to form a loop, thereby inputting a constant voltage AC signal into the slurry, and at the same time controls the sampling device to obtain an impedance response signal by connecting the probe to the slurry.

[0144] After the slurry obtains the excitation signal, the Nyquist diagram generation module 14 controls the sampling device to perform bandpass processing on the impedance response signal according to the preset sampling frequency range, and then performs sampling according to the set sampling number to form an impedance response signal. Subsequently, the impedance Nyquist diagram is drawn with the real part of the impedance as the horizontal axis and the negative imaginary part as the vertical axis as the electrochemical impedance data output.

[0145] In one embodiment, Figure 8 As shown, the atlas generation module 2 includes:

[0146] Function construction module 21, function construction module 21 constructs impedance relaxation distribution function according to electrochemical impedance data;

[0147] An interval interception module 22, the interval interception module 22 is connected to the function construction module 21;

[0148] The interval interception module 22 intercepts the relaxation distribution interval of the impedance relaxation distribution function according to a preset frequency range;

[0149] A graph construction module 23, the graph construction module 23 is connected to the interval interception module 22;

[0150] The spectrum construction module 23 draws a DRT spectrum according to the relaxation distribution interval.

[0151] Specifically, in order to realize the construction of the DRT spectrum, in this embodiment, the electrochemical impedance data is first analyzed on the time scale, and the function construction module 21 combines the relaxation distribution function to construct an impedance relaxation distribution function corresponding to the electrochemical impedance data. Subsequently, the interval interception module 22 extracts the impedance relaxation distribution function according to the frequency interval range to be analyzed subsequently, and obtains the relaxation distribution interval in the frequency range to be analyzed. Finally, the spectrum construction module 23 draws the DRT spectrum according to the relaxation distribution interval, thereby realizing effective characterization of the resistance and capacitance distribution of each component in the electrode slurry at different frequencies.

[0152] In one embodiment, Figure 9 As shown, the impedance data generating module 3 includes:

[0153] A characteristic peak extraction module 31 extracts a plurality of characteristic peaks from the DRT spectrum;

[0154] A characteristic peak identification module 32, the characteristic peak identification module 32 is connected to the characteristic peak extraction module 31;

[0155] The characteristic peak identification module 32 maps the characteristic peaks to multiple impedance parts in the fractional order model respectively;

[0156] Impedance calculation module 33, impedance calculation module 33 is connected to characteristic peak identification module 32;

[0157] The impedance calculation module 33 selects a characteristic peak corresponding to the impedance of the conductive path of the adhesive and calculates the peak area to obtain target impedance data.

[0158] Specifically, after the DRT spectrum is constructed, in order to effectively extract the target impedance data, the characteristic peak extraction module 31 first extracts a plurality of characteristic peaks from the DRT spectrum.

[0159] Specifically, according to the fractional-order model of electrode slurry, the electrode slurry can be equivalent to the ohmic internal resistance, the parallel link of resistor-constant phase element, and the Warburg impedance;

[0160] Among them, the parallel link of the resistor-constant phase element consists of the contact main material RC circuit, the adhesive conductive path RC circuit and the conductive agent RC circuit. These three RC circuits appear as peaks in three different stages on the DRT spectrum; the Warburg impedance represents the diffusion process and appears as a fourth peak on the DRT spectrum.

[0161] In the DRT spectrum, multiple characteristic peaks can be extracted based on amplitude variations. This can be done using amplitude or derivatives. Subsequently, the characteristic peak corresponding to the adhesive conductive path impedance is selected. Specifically, the characteristic peak identification module 32 reads the peaks sequentially according to the order on the DRT spectrum. When Peak 2 is read, the corresponding characteristic peak is the characteristic peak corresponding to the adhesive conductive path impedance. The impedance calculation module 33 calculates the peak area to obtain the target impedance data.

[0162] A memory includes computer instructions. When a computer device executes the computer instructions, the above-mentioned electrode slurry evaluation method is performed.

[0163] Those skilled in the art will appreciate that various aspects of the present invention, or possible implementations of various aspects, may be embodied as systems, methods, or computer program products. Thus, various aspects of the present invention, or possible implementations of various aspects, may take the form of complete hardware embodiments, complete software embodiments (including firmware, resident software, etc.), or embodiments combining software and hardware aspects, all collectively referred to herein as "circuits," "modules," or "systems." Furthermore, various aspects of the present invention, or possible implementations of various aspects, may take the form of computer program products, which refer to computer instructions stored in a memory.

[0164] The memory may be a computer-readable signal medium or a computer-readable storage medium. Computer-readable storage media include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or apparatuses, or any suitable combination thereof, such as random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, and portable read-only memory (CD-ROM).

[0165] The processor in the computer reads the computer instructions stored in the memory, so that the processor can perform the functional actions specified in each step or the combination of steps in the flowchart; and generate a device that implements the functional actions specified in each block or the combination of blocks in the block diagram.

[0166] It should be understood that the processor in the computer can be understood as one or more application-specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field programmable gate arrays (FPGAs), general-purpose processors, controllers, microcontrollers (MCUs), microprocessors, or other electronic components implemented to execute the aforementioned computer instructions.

[0167] Computer instructions can be executed entirely on the user's local computer, partially on the user's local computer, as a separate software package, partially on the user's local computer and partially on a remote computer, or entirely on a remote computer or server. It should also be noted that in certain alternative embodiments, the functions noted in each step of the flow chart or each block in the block diagram may not occur in the order noted in the figure. For example, depending on the functions involved, two steps or two blocks shown in succession may actually be executed approximately simultaneously, or the blocks may sometimes be executed in reverse order.

[0168] In practice, the various components of a computer system are coupled together via a bus system. It is understood that the bus system is used to enable communication between these components. In addition to the data bus, the bus system also includes a power bus, a control bus, and a status signal bus.

[0169] The above are only preferred embodiments of the present invention and do not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for evaluating electrode slurry based on DRT analysis, characterized in that: include: Step S1: performing an AC impedance test on the slurry to be tested to obtain electrochemical impedance data; Step S2: performing time relaxation processing on the electrochemical impedance spectroscopy data to obtain a DRT spectrum; Step S3: extracting target impedance data according to the DRT spectrum and the fractional order model of the slurry to be tested; The target impedance data is the impedance of the conductive path of the binder in the slurry to be tested; The target impedance data is used to determine the conductive properties of the slurry to be tested.

2. The electrode slurry evaluation method according to claim 1, characterized in that: The step S1 comprises: Step S11: setting the sampling frequency range and sampling number for the slurry to be tested; Step S12: connecting the slurry to be tested to an excitation device and a sampling device respectively; Step S13: applying a constant voltage AC signal to the slurry to be tested by using the excitation device, and collecting an impedance response signal of the slurry to be tested by using the sampling device; Step S14: drawing an impedance Nyquist plot according to the impedance response signal as the electrochemical impedance data; In the impedance Nyquist diagram, the real part of the impedance response signal is the horizontal axis, and the negative imaginary part is the vertical axis.

3. The electrode slurry evaluation method according to claim 1, characterized in that: The step S2 comprises: Step S21: constructing an impedance relaxation distribution function according to the electrochemical impedance data; Step S22: extracting a relaxation distribution interval of the impedance relaxation distribution function according to a preset frequency range; Step S23: drawing the DRT spectrum according to the relaxation distribution interval.

4. The electrode slurry evaluation method according to claim 3, characterized in that: In step S21, the impedance relaxation distribution function includes: Where Z(ω) is the total impedance, G(τ) is the relaxation distribution function, f is the frequency, i is the imaginary unit, ω is the angular frequency, and τ is the relaxation time.

5. The electrode slurry evaluation method according to claim 1, wherein: The step S3 comprises: Step S31: extracting multiple characteristic peaks from the DRT spectrum; Step S32: mapping the characteristic peaks to multiple impedance parts in the fractional-order model respectively; Step S33: selecting the characteristic peak corresponding to the impedance of the conductive path of the adhesive, and calculating the peak area to obtain the target impedance data.

6. The electrode slurry evaluation method according to claim 3, characterized in that: In step S3, the target impedance data calculation process includes: Where Z DRT is the target impedance data, τ is the relaxation time constant, G(τ) is the relaxation distribution function, f is the frequency, R ∞ is the ohmic impedance of the slurry to be tested.

7. The electrode slurry evaluation method according to claim 1, characterized in that: Before executing step S1, the method further includes: Step S01: preparing multiple groups of slurries to be tested using different recipes; After executing step S3, the method further includes: Step S4: comparing the slurry to be tested according to the target impedance data to determine a target formulation.

8. The electrode slurry evaluation method according to claim 1, wherein: The DRT diagram includes the contact main material RC circuit, the adhesive conductive path RC circuit, the conductive agent RC circuit and the Warburg impedance.

9. A memory comprising computer instructions, characterized in that When a computer device executes the computer instructions, the electrode slurry evaluation method according to any one of claims 1 to 8 is performed.

10. An evaluation system, characterized in that: Used to implement the electrode slurry evaluation method according to any one of claims 1 to 8; The evaluation system comprises: A measuring module, wherein the measuring module performs an AC impedance test on the slurry to be tested to obtain electrochemical impedance data; A spectrum generation module, the spectrum generation module is connected to the measurement module; The spectrum generating module performs time relaxation processing on the electrochemical impedance spectroscopy data to obtain a DRT spectrum; An impedance data generating module, the impedance data generating module being connected to the graph generating module; The impedance data generation module extracts target impedance data according to the DRT spectrum and the fractional order model of the slurry to be tested; The target impedance data is the impedance of the conductive path of the binder in the slurry to be tested; The target impedance data is used to determine the conductive properties of the slurry to be tested.

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