A performance evaluation method and system for lithium-ion battery negative electrode porous carbon material

Abstract

The present invention relates to the field of material science and technology, and specifically to a performance evaluation method and system for porous carbon materials for negative electrodes of lithium-ion batteries. By measuring physical performance indicators such as specific surface area, total pore volume, average pore size and graphitization degree of porous carbon materials, using electrochemical impedance spectroscopy to test electrochemical performance indicators such as ohmic resistance, charge transfer resistance, double layer capacitance and diffusion coefficient of porous carbon materials, constructing a two-dimensional matrix of physical performance and electrochemical performance to analyze the correlation, and drawing a radar chart of physicochemical performance to evaluate the comprehensive performance, a comprehensive, efficient and visual performance evaluation method is provided for the application of porous carbon materials in negative electrodes of lithium-ion batteries.

Description

Technical Field

[0001] The present invention relates to the field of material science and technology, and in particular to a performance evaluation method and system for a lithium ion battery negative electrode porous carbon material. Background Art

[0002] Lithium-ion batteries are widely used in portable electronic devices, electric vehicles, and energy storage systems. The negative electrode material is one of the key factors affecting the performance of lithium-ion batteries. Traditional graphite-based carbon materials have low specific capacity and can no longer meet the growing demand for energy storage. Porous carbon materials are ideal for lithium-ion battery negative electrode materials due to their high specific surface area, adjustable pore structure, and excellent conductivity.

[0003] However, the performance evaluation of porous carbon materials faces a series of challenges. First, the methods for characterizing the physical properties of porous carbon materials are relatively backward, making it difficult to accurately reflect the true structural characteristics of the materials. Second, the electrochemical performance evaluation methods of porous carbon materials in lithium-ion battery negative electrodes are not perfect, making it difficult to comprehensively examine the charge and discharge performance, rate performance, and cycle stability of the materials. Furthermore, the correlation mechanism between the physical properties and electrochemical properties of porous carbon materials is still unclear, and there is a lack of systematic structure-activity relationship research.

[0004] At present, the physical property characterization and electrochemical performance evaluation of porous carbon materials have problems such as complex sample preparation, long test cycle, poor result repeatability, lack of feedback on material structure information, and difficulty in establishing the correlation between performance and structure. The correlation analysis between the physicochemical properties and electrochemical properties of porous carbon materials mainly relies on experience summary and qualitative description, lacking quantitative mathematical models and visual analysis tools.

[0005] Therefore, it is necessary to develop a new method for evaluating the performance of porous carbon materials in order to achieve rapid and accurate characterization of the physical properties of the materials, comprehensively evaluate the electrochemical properties of the materials in the negative electrode of lithium-ion batteries, deeply understand the relationship between the structure and performance of the materials, and establish an intuitive and quantifiable comprehensive performance evaluation system.

[0006] In view of this, the present invention proposes a performance evaluation method and system for a lithium-ion battery negative electrode porous carbon material. Summary of the invention

[0007] To achieve the above object, the present invention provides a method for evaluating the performance of a porous carbon material for a negative electrode of a lithium ion battery. The specific technical scheme is as follows: obtaining a porous carbon material for a negative electrode of a lithium ion battery;

[0008] The physical properties of porous carbon materials are measured, including specific surface area, total pore volume, average pore size and degree of graphitization; the specific surface area of ​​porous carbon materials is measured based on nitrogen adsorption isotherms and BET theory; the total pore volume of porous carbon materials is measured based on the principle of capillary action; the average pore size of porous carbon materials is measured by improved dynamic fluid method; the degree of graphitization of porous carbon materials is measured based on Raman spectroscopy;

[0009] The electrochemical performance of the porous carbon material was tested. Electrochemical impedance spectroscopy (EIS) was used to test the electrochemical performance of the porous carbon material when it was used as the negative electrode of a lithium-ion battery. The ohmic resistance, charge transfer resistance, double-layer capacitance and diffusion coefficient of the porous carbon material were obtained through the electrochemical impedance spectroscopy (EIS) test.

[0010] Construct a two-dimensional matrix of physical properties and electrochemical properties of porous carbon materials, and calculate the correlation between physical performance indicators and electrochemical performance indicators using the Pearson correlation coefficient;

[0011] A radar chart of the physicochemical performance indicators of porous carbon materials is constructed to display the physical and electrochemical performance scores of the porous carbon materials, and the comprehensive performance of the porous carbon materials is evaluated based on the area of ​​the radar chart.

[0012] Preferably, the specific surface area of ​​the porous carbon material is measured using nitrogen adsorption isotherm and BET theory, taking the weight as The porous carbon material is subjected to a degassing treatment, and the porous carbon material is heated in a vacuum to remove pollutants and moisture adsorbed on the surface;

[0013] The porous carbon material is placed in a gas adsorption instrument, the relative pressure of nitrogen is increased, the nitrogen adsorption amount of the porous carbon material under different pressures is recorded, and the nitrogen adsorption isotherm is drawn according to the nitrogen adsorption amount;

[0014] The BET equation was used to fit the nitrogen adsorption isotherm. The BET equation is as follows:

[0015]

[0016] in, is the pressure of nitrogen; is the saturated vapor pressure of nitrogen; is the volume of nitrogen adsorbed under pressure; is the volume of gas required for adsorption by a single layer of porous carbon material; is the BET constant, which reflects the interaction between the adsorption layer and the adsorbed gas;

[0017] Perform linear regression on the linear part of the BET equation to determine Value and value;

[0018] according to Calculate the specific surface area of ​​porous carbon materials:

[0019]

[0020] in, is Avogadro's constant, is the effective cross-sectional area of ​​the nitrogen molecule; is the molar volume of nitrogen gas under standard conditions.

[0021] Preferably, based on the capillary action principle, the total pore volume of the porous carbon material is measured; a low viscosity liquid medium is selected, and the porous carbon material is immersed in a volume of in a liquid medium, after the porous carbon material is completely immersed in the liquid medium, ultrasonically oscillating the liquid medium, and stopping the ultrasonic oscillation when no bubbles are generated in the liquid medium;

[0022] Take out the porous carbon material after infiltration from the liquid medium and obtain the remaining liquid medium volume ; Calculate the total pore volume of porous carbon materials : ; is the total volume of the liquid medium; the total pore volume of the porous carbon material is measured multiple times and the average value is taken.

[0023] Preferably, the average pore size of the porous carbon material is measured by an improved dynamic fluid method; the porous carbon material is dried to remove the liquid and gas inside, and the cross-sectional area of ​​the porous carbon material is measured and recorded. and length L;

[0024] The porous carbon material is completely immersed in the driving liquid in the container, and a liquid inlet and a liquid outlet are respectively arranged above and below the container, and a pressure sensor and a flow meter are arranged at the liquid inlet and the liquid outlet to measure the pressure difference and flow rate of the driving liquid;

[0025] Apply different pressures to the inlet and outlet of the container. The pressure difference between the inlet and outlet is ;Measure the flow rate of the driving liquid through the sample ; Change the pressure difference in sequence , and repeatedly measure and record the driving liquid flow rate through the sample under different pressure conditions ;

[0026] According to Darcy's law, the flow rate is established Pressure difference Relationship:

[0027]

[0028] in, is the permeability, To drive the liquid viscosity;

[0029] By the Kozeny-Carman equation, the permeability Equivalent pore size to porous carbon materials The following relationship exists:

[0030]

[0031] in, is the porosity, is the Kozeny constant, reflecting the shape and tortuosity of the pore;

[0032] Solving for the equivalent pore size of porous carbon materials :

[0033]

[0034] Equivalent aperture It is the average pore size of porous carbon materials.

[0035] Preferably, the graphitization degree of the porous carbon material is measured based on Raman spectroscopy technology, the surface of the porous carbon material is polished, a Raman spectrometer is used, and an appropriate laser wavelength is selected to scan the sample to collect Raman spectral data;

[0036] Analyze the characteristic peaks of the Raman spectrum, wherein the characteristic peaks of the Raman spectrum include a D peak and a G peak, and the integrated intensity ratio of the D peak and the G peak of the characteristic peak of the Raman spectrum is , is the integrated intensity of the D peak, is the integrated intensity of the G peak; a quantitative characterization model for the graphitization degree of porous carbon materials is established;

[0037] Considering the size of graphite crystallites in porous carbon materials The influence on Raman spectroscopy is introduced by the Tuinstra-Koenig formula:

[0038]

[0039] in, is a constant related to the laser wavelength. By fitting the Raman spectral data of a large number of samples with known graphitization degrees, Quantitative relationship with graphitization degree:

[0040]

[0041] Among them, a, b, and c are fitting parameters obtained through experiments on carbon materials;

[0042] The porous carbon material is tested by Raman spectroscopy to obtain the integrated intensity ratio R of the D peak and the G peak. The R value is substituted into the quantitative characterization model of graphitization degree to calculate the graphitization degree G of the porous carbon material.

[0043] Preferably, electrochemical impedance spectroscopy (EIS) is used to test the electrochemical performance of the porous carbon material when it is applied to the negative electrode of a lithium-ion battery; the porous carbon material to be tested is prepared into a battery electrode, and a three-electrode system is used, in which the porous carbon material is used as a working electrode, a lithium sheet is used as a counter electrode, and silver chloride is used as a reference electrode;

[0044] Connect the assembled battery to the electrochemical workstation, set the EIS parameters, set the frequency range, AC excitation intensity and test points;

[0045] When the battery is in a stable state, a sinusoidal AC excitation signal is applied to the battery, and the signal is scanned within the set frequency range to measure the corresponding signal of the battery. That is, the battery impedance at different frequencies is calculated based on the changes in the battery current and voltage.

[0046] At each frequency point, the corresponding electrical signal of the battery is automatically recorded by the electrochemical workstation, and the EIS spectrum of the battery is obtained after data acquisition;

[0047] Analyze the EIS spectrum and plot the collected data into an EIS spectrum, wherein the EIS spectrum includes a Nyquist diagram and a Bode diagram;

[0048] According to the characteristics of the EIS spectrum, an equivalent circuit model is set, wherein the equivalent circuit model includes a Randles circuit and a Voigt circuit; the EIS data is fitted using the software of the electrochemical workstation to obtain the parameter values ​​of each component in the equivalent circuit;

[0049] According to the parameter values ​​obtained by equivalent circuit fitting, the key performance indicators of the battery are calculated to obtain the electrochemical properties of the porous carbon material when applied to the negative electrode of the lithium-ion battery, which include ohmic resistance , Charge transfer resistance , double layer capacitor and diffusion coefficient .

[0050] Preferably, a two-dimensional matrix of physical properties and electrochemical properties of the porous carbon material is constructed, and the correlation between the physical performance index and the electrochemical performance index is calculated by a Pearson correlation coefficient matrix;

[0051] A porous carbon material was constructed based on its physical properties, such as specific surface area, total pore volume, average pore size and degree of graphitization, and electrochemical properties, such as ohmic resistance, charge transfer resistance, double layer capacitance and diffusion coefficient. The matrix M, where is the amount of porous carbon material;

[0052] Fill the physical and electrochemical performance indicators of the porous carbon material into the matrix M:

[0053]

[0054] The Pearson correlation coefficient was used to calculate the correlation between physical performance indicators and electrochemical performance indicators:

[0055]

[0056] in, and Respectively represent The first porous carbon material The physical performance index and Electrochemical performance indicators; and Respectively represent The physical performance index and The average value of the electrochemical performance indicators;

[0057] According to the correlation coefficient matrix , analyze the correlation between the physical performance indicators and electrochemical performance indicators of porous carbon materials:

[0058] when When The physical performance index and There is a strong correlation between the electrochemical performance indicators;

[0059] when When The physical performance index and There is a moderate correlation between the electrochemical performance indicators;

[0060] when When The physical performance index and There is a weak correlation between the electrochemical performance indicators.

[0061] Preferably, a radar chart of the physicochemical performance indicators of the porous carbon material is constructed to display the physical and electrochemical properties of the porous carbon material;

[0062] The specific surface area, total pore volume, average pore size and degree of graphitization in the physical properties of porous carbon materials, as well as the ohmic resistance, charge transfer resistance, double layer capacitance and diffusion coefficient in electrochemistry, are standardized to unify the data of various performance indicators of porous carbon materials into Within the range:

[0063]

[0064] in, The first Performance index value, is the original data, and are the minimum and maximum values ​​of the indicator respectively;

[0065] Draw a radar chart with each standardized performance indicator value as the radius. Each angle axis in the radar chart represents a performance indicator, and connect the points to form a closed polygon.

[0066] Calculate the area enclosed by the radar chart : ; As a quantitative evaluation index for the comprehensive performance of porous carbon materials.

[0067] A performance evaluation system for a lithium-ion battery negative electrode porous carbon material, which is implemented based on the performance evaluation method for a lithium-ion battery negative electrode porous carbon material, comprises: a material acquisition module, a physical property measurement module, an electrochemical property measurement module, a correlation calculation module and a radar chart scoring module;

[0068] The material acquisition module is used to obtain the porous carbon material for the negative electrode of the lithium-ion battery;

[0069] The physical property measurement module is used to measure the physical properties of porous carbon materials, including specific surface area, total pore volume, average pore diameter and degree of graphitization; the specific surface area of ​​porous carbon materials is measured based on nitrogen adsorption isotherm and BET theory; the total pore volume of porous carbon materials is measured based on the principle of capillary action; the average pore diameter of porous carbon materials is measured by improved dynamic fluid method; and the degree of graphitization of porous carbon materials is measured based on Raman spectroscopy technology;

[0070] The electrochemical performance calculation module is used to test the electrochemical performance of the porous carbon material, and adopts electrochemical impedance spectroscopy (EIS) to test the electrochemical performance of the porous carbon material when it is applied to the negative electrode of a lithium-ion battery, and obtains the ohmic resistance, charge transfer resistance, double-layer capacitance and diffusion coefficient of the porous carbon material through the electrochemical impedance spectroscopy (EIS) test;

[0071] The correlation calculation module is used to construct a two-dimensional matrix of physical properties and electrochemical properties of porous carbon materials, and calculate the correlation between physical performance indicators and electrochemical performance indicators through the Pearson correlation coefficient;

[0072] The radar chart scoring module is used to construct a radar chart of the physicochemical performance indicators of the porous carbon material, display the physical and electrochemical performance scores of the porous carbon material, and evaluate the comprehensive performance of the porous carbon material according to the area of ​​the radar chart.

[0073] An electronic device comprises: a processor and a memory, wherein the memory stores a computer program that can be called by the processor; the processor executes the performance evaluation method of a lithium-ion battery negative electrode porous carbon material by calling the computer program stored in the memory.

[0074] A computer-readable storage medium includes: instructions stored therein, and when the instructions are run on a computer, the computer is enabled to execute the performance evaluation method of a porous carbon material for a negative electrode of a lithium-ion battery.

[0075] Beneficial effects of the present invention: The present invention adopts nitrogen adsorption isotherm and BET theory, which is easy to operate and has high measurement accuracy. Compared with the traditional single-point BET method, the multi-point BET method of the present invention can more accurately describe the adsorption characteristics of porous materials.

[0076] The present invention is based on the principle of capillary action. By measuring the volume of liquid medium absorbed by porous carbon materials, the total pore volume data can be obtained quickly and easily. By introducing ultrasonic oscillation, the liquid medium can be promoted to fully infiltrate the pores, thereby improving the accuracy of the measurement. Compared with the traditional gas adsorption method, the present invention is simpler to operate and has a shorter test cycle.

[0077] The improved dynamic fluid method of the present invention measures the seepage velocity of the driving liquid in the porous carbon material and combines it with the Kozeny-Carman equation to calculate the equivalent pore size of the material, that is, the average pore size. Compared with the traditional mercury injection method and gas adsorption method, the method of the present invention does not require the use of toxic substances, and the testing process is non-destructive.

[0078] The present invention is based on Raman spectroscopy technology. By analyzing the intensity ratio of the characteristic peaks (D peak and G peak) of porous carbon materials and considering the influence of graphite crystallite size, a quantitative characterization model of graphitization degree is established. Compared with the traditional XRD method and resistivity method, the Raman spectroscopy method of the present invention can provide richer structural information and is applicable to carbon materials of various morphologies.

[0079] The present invention adopts electrochemical impedance spectroscopy (EIS) testing to comprehensively evaluate the electrochemical properties of porous carbon materials in the negative electrode of lithium-ion batteries, obtain key parameters such as ohmic resistance, charge transfer resistance, double-layer capacitance and diffusion coefficient, and provide guidance for material performance optimization. The EIS test can provide kinetic information of the electrode process, and the test process is non-destructive, and in-situ characterization can be achieved.

[0080] The present invention constructs a two-dimensional matrix of physical properties and electrochemical properties of porous carbon materials, integrates multiple performance indicators of the material into the same mathematical model, and realizes a comprehensive evaluation of the performance. Through the Pearson correlation coefficient matrix, the correlation between the various performance indicators can be quantitatively analyzed to reveal the intrinsic connection between the material structure and performance.

[0081] The present invention constructs a radar chart of the physicochemical performance indicators of porous carbon materials, intuitively displays various performance indicators of the materials, and facilitates comparison of performance differences between different materials. Through area calculation, the comprehensive performance of porous carbon materials can be quantitatively evaluated, providing a criterion for material optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 A schematic diagram of a performance evaluation method for a lithium-ion battery negative electrode porous carbon material according to the present invention;

[0083] Figure 2 This is a schematic diagram of the structure of a performance evaluation system for a lithium-ion battery negative electrode porous carbon material according to the present invention;

[0084] Figure 3 is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention;

[0085] Figure 4 It is a schematic diagram of the structure of a computer-readable storage medium provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0086] In order to better understand the present invention, a more detailed description will be made of various aspects of the present invention with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0087] In the accompanying drawings, the size, dimensions and shapes of the elements have been slightly adjusted for ease of illustration. The accompanying drawings are for illustration only and are not strictly drawn to scale. As used herein, the terms "substantially", "approximately" and similar terms are used as terms of approximation, not as terms of degree, and are intended to illustrate the inherent deviations in measurements or calculations that will be recognized by those of ordinary skill in the art. In addition, in the present invention, the order in which the steps are described does not necessarily represent the order in which these processes occur in actual operation, unless otherwise specified or can be derived from the context.

[0088] It should also be understood that expressions such as "comprises", "including", "having", "includes" and / or "comprising" are open rather than closed expressions in this specification, which indicate the presence of the stated features, elements and / or components, but do not exclude the presence of one or more other features, elements, components and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features rather than just the individual elements in the list. In addition, when describing embodiments of the present invention, "may" is used to mean "one or more embodiments of the present invention". And, the term "exemplary" is intended to refer to an example or illustration.

[0089] Unless otherwise defined, all terms (including engineering terms and scientific and technological terms) used in this document have the same meaning as commonly understood by ordinary technicians in the field to which the present invention belongs. It should also be understood that unless otherwise clearly stated in the present invention, words defined in commonly used dictionaries should be interpreted as having the same meaning as their meaning in the context of the relevant technology, and should not be interpreted in an idealized or overly formal sense.

[0090] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0091] Example 1

[0092] Reference Figure 1 The first embodiment of the present invention provides a method for evaluating the performance of a porous carbon material for a negative electrode of a lithium-ion battery.

[0093] S1: Measure the physical properties of porous carbon materials, including specific surface area, total pore volume, average pore size and degree of graphitization; measure the specific surface area of ​​porous carbon materials based on nitrogen adsorption isotherm and BET theory; measure the total pore volume of porous carbon materials based on the principle of capillary action; measure the average pore size of porous carbon materials using the improved dynamic fluid method; and measure the degree of graphitization of porous carbon materials based on Raman spectroscopy.

[0094] S101: Use nitrogen adsorption isotherms and BET theory to measure the specific surface area of ​​porous carbon materials, obtain porous carbon materials, degas the porous carbon materials, and remove pollutants and moisture adsorbed on the surface of the porous carbon materials by vacuum heating.

[0095] The porous carbon material is placed in a gas adsorption instrument. In a liquid nitrogen low-temperature environment, the relative pressure of nitrogen is increased. The nitrogen adsorption amount of the porous carbon material under different pressures is recorded. Based on the nitrogen adsorption amount, a nitrogen adsorption isotherm is drawn.

[0096] The BET equation was used to fit the nitrogen adsorption isotherm. The BET equation is as follows:

[0097]

[0098] in, is the pressure of nitrogen; is the saturated vapor pressure of nitrogen; is the volume of nitrogen adsorbed under pressure; is the volume of gas required for adsorption by a single layer of porous carbon material; is the BET constant, which reflects the interaction between the adsorption layer and the adsorbed gas.

[0099] Perform linear regression on the linear part of the BET equation to determine Value and value;

[0100] according to Calculate the specific surface area of ​​porous carbon materials:

[0101]

[0102] in, is Avogadro's constant, is the effective cross-sectional area of ​​the nitrogen molecule; is the molar volume of nitrogen gas under standard conditions.

[0103] The present invention adopts nitrogen adsorption isotherm and BET theory, which is easy to operate and has high measurement accuracy, and can obtain specific surface area data of porous carbon materials. Superior to the traditional single-point BET method, the multi-point BET method of the present invention can more accurately describe the adsorption characteristics of porous materials.

[0104] S102: Based on the principle of capillary action, measure the total pore volume of porous carbon materials; select a low-viscosity liquid medium and immerse the porous carbon material in a volume of In a liquid medium, after the porous carbon material is completely immersed in the liquid medium, the liquid medium is ultrasonically oscillated, and the ultrasonic oscillation is stopped when no bubbles are generated in the liquid medium; the ultrasonic oscillation can ensure that the pores of the sample to be tested are fully infiltrated with the liquid medium.

[0105] Based on the principle of capillary action, the liquid medium is sucked into the pores of the porous carbon material, and the porous carbon material is taken out from the liquid medium to obtain the remaining liquid medium volume. ; Calculate the total pore volume of porous carbon materials : ; is the total volume of the liquid medium; the total pore volume of the porous carbon material is measured multiple times and the average value is taken.

[0106] Based on the principle of capillary action, the total pore volume data can be obtained quickly and easily by measuring the volume of liquid medium absorbed by porous carbon materials. The introduction of ultrasonic oscillation can promote the liquid medium to fully infiltrate the pores and improve the accuracy of the measurement. Compared with the traditional gas adsorption method, the method of the present invention is simpler to operate and has a shorter test cycle.

[0107] S103: Improve the dynamic fluid method to measure the average pore size of porous carbon materials; dry the porous carbon materials, remove the liquid and gas inside, measure and record the cross-sectional area of ​​the porous carbon materials and length L.

[0108] The porous carbon material is completely immersed in the driving liquid in the container, and a liquid inlet and a liquid outlet are respectively arranged above and below the container. Pressure sensors and flow meters are arranged at the liquid inlet and the liquid outlet to measure the pressure difference and flow rate of the driving liquid; water is used as the driving liquid.

[0109] Apply different pressures to the inlet and outlet of the container. The pressure difference between the inlet and outlet is ; Ensure the driving liquid flows through the pores of the porous carbon material by setting up a pressure difference; measure the flow rate of the driving liquid through the sample ; Change the pressure difference in sequence , and repeatedly measure and record the driving liquid flow rate through the sample under different pressure conditions .

[0110] According to Darcy's law, the flow rate is established Pressure difference Relationship:

[0111]

[0112] in, is the permeability, To drive the liquid viscosity;

[0113] By the Kozeny-Carman equation, the permeability Equivalent pore size to porous carbon materials The following relationship exists:

[0114]

[0115] in, is the porosity, is the Kozeny constant, reflecting the shape and tortuosity of the pore;

[0116] Solving for the equivalent pore size of porous carbon materials :

[0117]

[0118] Equivalent aperture It is the average pore size of the porous carbon material.

[0119] The improved dynamic fluid method of the present invention measures the seepage velocity of the driving liquid in the porous carbon material and combines it with the Kozeny-Carman equation to calculate the equivalent pore size of the material, that is, the average pore size. The present invention fully considers the influence of the shape and tortuosity of the pores on the seepage, and the measurement results are more reliable. Compared with the traditional mercury injection method and gas adsorption method, the method of the present invention does not require the use of toxic substances, and the testing process is non-destructive.

[0120] S104: Measure the graphitization degree of porous carbon materials based on Raman spectroscopy technology, polish the surface of the porous carbon materials to ensure that the surface of the porous carbon materials is smooth and uniform; use a Raman spectrometer to quickly scan the sample, select an appropriate laser wavelength (such as 532nm or 785nm), and collect Raman spectral data.

[0121] The characteristic peaks of the Raman spectrum include D peak and G peak, and the D peak is about 1350 cm -1 , the G peak is about 1580cm -1 , the integrated intensity ratio of the characteristic peaks of the Raman spectrum, D peak and G peak , is the integrated intensity of the D peak, is the integrated intensity of the G peak; a quantitative characterization model for the degree of graphitization of porous carbon materials is established.

[0122] Considering the size of graphite crystallites in porous carbon materials The influence on Raman spectroscopy is introduced by the Tuinstra-Koenig formula:

[0123]

[0124] in, is a constant related to the laser wavelength. By fitting the Raman spectral data of a large number of samples with known graphitization degrees, Quantitative relationship with graphitization degree:

[0125]

[0126] Among them, a, b, and c are fitting parameters obtained through experiments on carbon materials.

[0127] The porous carbon material is tested by Raman spectroscopy to obtain the integrated intensity ratio R of the D peak and the G peak. The R value is substituted into the quantitative characterization model of graphitization degree to calculate the graphitization degree G of the porous carbon material.

[0128] Based on Raman spectroscopy, by analyzing the intensity ratio of the characteristic peaks (D peak and G peak) of porous carbon materials and considering the influence of graphite crystallite size, a quantitative characterization model of graphitization degree is established. The method provided by the present invention is simple to operate, has low sample preparation requirements, fast test speed, and non-contact measurement avoids damage to the sample. Compared with the traditional XRD method and resistivity method, the Raman spectroscopy of the present invention can provide richer structural information and is applicable to carbon materials of various morphologies.

[0129] The above are some innovative and improved measurement methods for the four key physical and chemical performance indicators of porous carbon materials. These methods simplify the test process, reduce equipment requirements, and improve test efficiency, while taking into account the accuracy and reliability of the test results. In practical applications, these methods can be flexibly selected and optimized according to specific needs and conditions, in order to obtain faster, more economical, and more environmentally friendly means of characterizing the physical and chemical properties of materials, providing strong support for the development and evaluation of porous carbon materials.

[0130] S2: Conduct electrochemical performance tests on porous carbon materials. Use electrochemical impedance spectroscopy (EIS) to test the electrochemical performance of porous carbon materials when used in negative electrodes of lithium-ion batteries. The electrochemical properties of the porous carbon materials, such as ohmic resistance, charge transfer resistance, double-layer capacitance and diffusion coefficient, are obtained through electrochemical impedance spectroscopy (EIS).

[0131] Electrochemical impedance spectroscopy (EIS) was used to test the electrochemical performance of porous carbon materials when used in the negative electrode of lithium-ion batteries. The porous carbon material to be tested was prepared into a battery electrode, and a three-electrode system was used, with the porous carbon material as the working electrode, the lithium sheet as the counter electrode, and silver chloride as the reference electrode.

[0132] Connect the assembled battery to the electrochemical workstation, set the EIS parameters, set the frequency range, AC excitation intensity and number of test points.

[0133] Before conducting the EIS test, the battery is first subjected to a stability test to ensure that the battery is in a stable state, using constant current charge and discharge or constant potential polarization until the battery open circuit voltage or current reaches stability.

[0134] In a stable state, a sinusoidal AC excitation signal is applied to the battery, scanned within the set frequency range, and the corresponding signal of the battery is measured. That is, the battery impedance at different frequencies is calculated based on the changes in battery current and voltage.

[0135] At each frequency point, the corresponding electrical signal of the battery is automatically recorded by the electrochemical workstation, and the real part is calculated. and the imaginary part ; After data collection is completed, the EIS spectrum of the battery is obtained.

[0136] The EIS spectrum is analyzed, and the collected data is plotted into an EIS spectrum, wherein the EIS spectrum includes a Nyquist diagram and a Bode diagram.

[0137] According to the characteristics of the EIS spectrum, an equivalent circuit model is set, and the equivalent circuit model includes a Randles circuit and a Voigt circuit; the EIS data is fitted using the software of the electrochemical workstation to obtain the parameter values ​​of each component in the equivalent circuit.

[0138] According to the parameter values ​​obtained by equivalent circuit fitting, the key performance indicators of the battery are calculated to obtain the electrochemical properties of the porous carbon material when applied to the negative electrode of the lithium-ion battery, which include ohmic resistance , Charge transfer resistance , double layer capacitor and diffusion coefficient .

[0139] According to the parameter values ​​obtained by equivalent circuit fitting, the key performance indicators of the battery, ohmic resistance, are calculated. , Charge transfer resistance , double layer capacitor and diffusion coefficient .

[0140] The impedance calculation formula is:

[0141]

[0142] in, is the complex impedance, is the real part, is the imaginary part, is an imaginary unit, is the angular frequency.

[0143] The impedance formula of the Randles equivalent circuit is:

[0144]

[0145] Solving for the Charge Transfer Resistance The calculation formula is:

[0146]

[0147] in, is the ohmic resistance, is the charge transfer resistance, is the double layer capacitance, is the Warburg impedance.

[0148] The calculation formula of Warburg impedance is:

[0149]

[0150] in, is the Warburg coefficient, which is related to the diffusion coefficient D. The calculation formula is:

[0151]

[0152] Where R is the gas constant, T is the absolute temperature, n is the number of reaction electrons, and F is the Faraday constant. is the electrode area; c is the electrolyte concentration.

[0153] The calculation formula of the diffusion coefficient D is:

[0154]

[0155] The diffusion coefficient D can be calculated from the slope or intercept of the Warburg impedance.

[0156] S3: Construct a two-dimensional matrix of the physical properties and electrochemical properties of porous carbon materials, and calculate the correlation between the physical performance indicators and the electrochemical performance indicators through the Pearson correlation coefficient matrix.

[0157] A porous carbon material was constructed based on its physical properties, such as specific surface area, total pore volume, average pore size and degree of graphitization, and electrochemical properties, such as ohmic resistance, charge transfer resistance, double layer capacitance and diffusion coefficient. The matrix M, where is the number of porous carbon materials, and 8 is the total number of physical performance indicators and electrochemical performance indicators.

[0158] Fill the physical and electrochemical performance indicators of the porous carbon material into the matrix M:

[0159]

[0160] The Pearson correlation coefficient was used to calculate the correlation between physical performance indicators and electrochemical performance indicators:

[0161]

[0162] in, and Respectively represent The first porous carbon material The physical performance index and Electrochemical performance indicators; and Respectively represent The physical performance index and The average value of the electrochemical performance indicators.

[0163] According to the correlation coefficient matrix , analyze the correlation between the physical performance indicators and electrochemical performance indicators of porous carbon materials:

[0164] when When The physical performance index and There is a strong correlation between the electrochemical performance indicators;

[0165] when When The physical performance index and There is a moderate correlation between the electrochemical performance indicators;

[0166] when When The physical performance index and There is a weak correlation between the electrochemical performance indicators.

[0167] By constructing a two-dimensional matrix of physical properties and electrochemical properties of porous carbon materials, multiple performance indicators of the material are integrated into the same mathematical model, achieving a comprehensive evaluation of the performance. The Pearson correlation coefficient matrix can then be used to quantitatively analyze the correlation between the various performance indicators and reveal the intrinsic connection between the material structure and performance. The method of the present invention can comprehensively examine the comprehensive performance of the material and provide a more scientific basis for material design and screening.

[0168] S4: Construct a radar chart of the physicochemical performance indicators of porous carbon materials to display the physical and electrochemical properties of porous carbon materials.

[0169] The specific surface area, total pore volume, average pore size and degree of graphitization in the physical properties of porous carbon materials, as well as the ohmic resistance, charge transfer resistance, double layer capacitance and diffusion coefficient in electrochemistry, are standardized to unify the data of various performance indicators of porous carbon materials into Within the range:

[0170]

[0171] in, The first Performance index value, is the original data, and are the minimum and maximum values ​​of the indicator respectively;

[0172] Draw a radar chart with each standardized performance indicator value as the radius. Each angle axis in the radar chart represents a performance indicator, and connect the points to form a closed polygon.

[0173] Calculate the area enclosed by the radar chart : ; As a quantitative evaluation index for the comprehensive performance of porous carbon materials.

[0174] By constructing a radar chart of the physical and chemical performance indicators of porous carbon materials, the various performance indicators of the materials can be intuitively displayed, making it easier to compare the performance differences between different materials. Based on the calculation of the radar chart area, the comprehensive performance of porous carbon materials can be quantitatively evaluated, providing a criterion for material optimization.

[0175] Example 2

[0176] Reference Figure 2 The second embodiment of the present invention provides a performance evaluation system for a lithium-ion battery negative electrode porous carbon material.

[0177] The system includes: a material acquisition module, a physical property calculation module, an electrochemical property calculation module, a correlation calculation module and a radar chart scoring module.

[0178] The material acquisition module is used to obtain the porous carbon material for the negative electrode of the lithium-ion battery.

[0179] The physical property measurement module is used to measure the physical properties of porous carbon materials, including specific surface area, total pore volume, average pore diameter and degree of graphitization; the specific surface area of ​​porous carbon materials is measured based on nitrogen adsorption isotherms and BET theory; the total pore volume of porous carbon materials is measured based on the principle of capillary action; the average pore diameter of porous carbon materials is measured by improved dynamic fluid method; and the degree of graphitization of porous carbon materials is measured based on Raman spectroscopy technology.

[0180] The electrochemical performance calculation module is used to test the electrochemical performance of the porous carbon material. The electrochemical impedance spectroscopy (EIS) is used to test the electrochemical performance of the porous carbon material when it is applied to the negative electrode of a lithium-ion battery. The electrochemical performance of the porous carbon material, including its ohmic resistance, charge transfer resistance, double-layer capacitance and diffusion coefficient, is obtained through the electrochemical impedance spectroscopy (EIS) test.

[0181] The correlation calculation module is used to construct a two-dimensional matrix of physical properties and electrochemical properties of porous carbon materials, and calculate the correlation between physical performance indicators and electrochemical performance indicators through the Pearson correlation coefficient.

[0182] The radar chart scoring module is used to construct a radar chart of the physicochemical performance indicators of the porous carbon material, display the physical and electrochemical performance scores of the porous carbon material, and evaluate the comprehensive performance of the porous carbon material according to the area of ​​the radar chart.

[0183] Example 3

[0184] Figure 3FIG. 1 is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. Figure 3 As shown, according to another aspect of the present invention, an electronic device 500 is also provided. The electronic device 500 may include one or more processors and one or more memories. The memories store computer readable codes, and when the computer readable codes are run by one or more processors, the performance evaluation method of the porous carbon material for the negative electrode of a lithium ion battery as described above can be executed.

[0185] The method or system according to the embodiment of the present invention can also be used by Figure 3 The architecture of the electronic device shown is implemented.

[0186] like Figure 3 As shown, the electronic device 500 may include a bus 501, one or more CPUs 502, a read-only memory (ROM) 503, a random access memory (RAM) 504, a communication port 505 connected to a network, an input / output component 506, a hard disk 507, and the like.

[0187] The storage device in the electronic device 500, such as the ROM 503 or the hard disk 507, can store the performance evaluation method of the porous carbon material for the negative electrode of a lithium ion battery provided by the present invention.

[0188] A performance evaluation method for a lithium-ion battery negative electrode porous carbon material comprises: obtaining a lithium-ion battery negative electrode porous carbon material; measuring physical properties of the porous carbon material, including specific surface area, total pore volume, average pore size and degree of graphitization; measuring the specific surface area of ​​the porous carbon material based on nitrogen adsorption isotherm and BET theory; measuring the total pore volume of the porous carbon material based on the capillary action principle; measuring the average pore size of the porous carbon material by an improved dynamic fluid method; measuring the degree of graphitization of the porous carbon material based on Raman spectroscopy; and testing the electrochemical performance of the porous carbon material by using an electrochemical resistor. The electrochemical properties of porous carbon materials when used in the negative electrode of lithium-ion batteries are tested by anti-EIS. The electrochemical properties of the porous carbon materials, such as ohmic resistance, charge transfer resistance, double-layer capacitance and diffusion coefficient, are obtained through electrochemical impedance spectroscopy (EIS) testing. A two-dimensional matrix of the physical properties and electrochemical properties of porous carbon materials is constructed, and the correlation between the physical performance indicators and the electrochemical performance indicators is calculated through the Pearson correlation coefficient. A radar chart of the physicochemical performance indicators of porous carbon materials is constructed to display the physical and electrochemical performance scores of the porous carbon materials, and the comprehensive performance of the porous carbon materials is evaluated based on the area of ​​the radar chart.

[0189] Furthermore, the electronic device 500 may also include a user interface 508. Figure 3 The architecture shown is only exemplary and can be omitted according to actual needs when implementing different devices. Figure 3 One or more components of an electronic device are shown.

[0190] Example 4

[0191] Figure 4 It is a schematic diagram of the structure of a computer-readable storage medium provided by an embodiment of the present invention.

[0192] like Figure 4 As shown, a computer readable storage medium 600 according to one embodiment of the present invention.

[0193] Computer readable storage medium 600 has computer readable instructions stored thereon.

[0194] When the computer-readable instructions are executed by a processor, the performance evaluation method of a negative-electrode porous carbon material for a lithium-ion battery according to an embodiment of the present invention described with reference to the above drawings can be executed.

[0195] The storage medium 600 includes, but is not limited to, for example, volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and cache memory (cache), etc. Non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. In addition, according to an embodiment of the present invention, the process described above with reference to the flowchart may be implemented as a computer software program.

[0196] For example, the present invention provides a non-temporary machine-readable storage medium, which stores machine-readable instructions, and the machine-readable instructions can be run by a processor to execute instructions corresponding to the method steps provided by the present invention, such as: obtaining a porous carbon material for a negative electrode of a lithium-ion battery; measuring the physical properties of the porous carbon material, including specific surface area, total pore volume, average pore size and degree of graphitization; measuring the specific surface area of ​​the porous carbon material based on nitrogen adsorption isotherms and BET theory; measuring the total pore volume of the porous carbon material based on the principle of capillary action; measuring the average pore size of the porous carbon material using an improved dynamic fluid method; measuring the porous carbon material based on Raman spectroscopy. The graphitization degree of carbon materials; the electrochemical performance test of porous carbon materials, the electrochemical impedance spectroscopy (EIS) test of the electrochemical performance of porous carbon materials when used in the negative electrode of lithium-ion batteries, the electrochemical properties of the porous carbon materials such as ohmic resistance, charge transfer resistance, double layer capacitance and diffusion coefficient are obtained through the electrochemical impedance spectroscopy (EIS) test; a two-dimensional matrix of the physical properties and electrochemical properties of porous carbon materials is constructed, and the correlation between the physical performance indicators and the electrochemical performance indicators is calculated through the Pearson correlation coefficient; a radar chart of the physicochemical performance indicators of porous carbon materials is constructed to display the physical properties and electrochemical performance scores of porous carbon materials, and the comprehensive performance of porous carbon materials is evaluated according to the area of ​​the radar chart.

[0197] When the computer program is executed by the central processing unit (CPU), the above functions defined in the method of the present invention are performed. The method, apparatus, and device of the present invention may be implemented in many ways. For example, the method, apparatus, and device of the present invention may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware.

[0198] The above sequence for the steps of the method is for illustration only, and the steps of the method of the present invention are not limited to the sequence specifically described above unless otherwise specifically stated.

[0199] In addition, in some embodiments, the present invention can also be implemented as a program recorded in a recording medium, which includes machine-readable instructions for implementing the method according to the present invention. Therefore, the present invention also covers a recording medium storing a program for executing the method according to the present invention.

[0200] In addition, the parts of the above technical solutions provided in the embodiments of the present invention that are consistent with the implementation principles of the corresponding technical solutions in the prior art are not described in detail to avoid excessive redundancy.

[0201] The specific implementation modes as described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation mode of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for evaluating the performance of a lithium-ion battery negative electrode porous carbon material, characterized in that: include: Obtaining porous carbon materials for negative electrodes of lithium-ion batteries; Physical properties of porous carbon materials were measured, including specific surface area, total pore volume, average pore diameter and degree of graphitization; The specific surface area of ​​porous carbon materials was measured based on nitrogen adsorption isotherms and BET theory; Based on the principle of capillary action, the total pore volume of porous carbon materials is measured; Improved dynamic fluid method to measure the average pore size of porous carbon materials; Measuring the graphitization degree of porous carbon materials based on Raman spectroscopy; The electrochemical performance of the porous carbon material was tested. Electrochemical impedance spectroscopy (EIS) was used to test the electrochemical performance of the porous carbon material when it was used as the negative electrode of a lithium-ion battery. The ohmic resistance, charge transfer resistance, double-layer capacitance and diffusion coefficient of the porous carbon material were obtained through the electrochemical impedance spectroscopy (EIS) test. Construct a two-dimensional matrix of physical properties and electrochemical properties of porous carbon materials, and calculate the correlation between physical performance indicators and electrochemical performance indicators using the Pearson correlation coefficient; A porous carbon material was constructed based on its physical properties, such as specific surface area, total pore volume, average pore size and degree of graphitization, and electrochemical properties, such as ohmic resistance, charge transfer resistance, double layer capacitance and diffusion coefficient. The matrix M, where is the amount of porous carbon material; Fill the physical and electrochemical performance indicators of the porous carbon material into the matrix M: ； The Pearson correlation coefficient was used to calculate the correlation between physical performance indicators and electrochemical performance indicators: ； in, and Respectively represent The first porous carbon material The physical performance index and Electrochemical performance indicators; and Respectively represent The physical performance index and The average value of the electrochemical performance indicators; Construct a radar chart of the physicochemical performance indicators of porous carbon materials to display the physical and electrochemical performance scores of porous carbon materials, and evaluate the comprehensive performance of porous carbon materials based on the area of ​​the radar chart; The specific surface area, total pore volume, average pore size and degree of graphitization in the physical properties of porous carbon materials, as well as the ohmic resistance, charge transfer resistance, double layer capacitance and diffusion coefficient in electrochemistry, are standardized to unify the data of various performance indicators of porous carbon materials into Within the range: ； in, The first Performance index value, is the original data, and are the minimum and maximum values ​​of the indicator respectively; Draw a radar chart with each standardized performance indicator value as the radius. Each angle axis in the radar chart represents a performance indicator, and connect the points to form a closed polygon. Calculate the area enclosed by the radar chart : ; As a quantitative evaluation index for the comprehensive performance of porous carbon materials.

2. The method for evaluating the performance of a lithium-ion battery negative electrode porous carbon material according to claim 1, characterized in that: The specific surface area of ​​porous carbon materials was measured using nitrogen adsorption isotherms and BET theory. The porous carbon material is subjected to a degassing treatment, and the porous carbon material is heated in a vacuum to remove pollutants and moisture adsorbed on the surface; The porous carbon material is placed in a gas adsorption instrument, the relative pressure of nitrogen is increased, the nitrogen adsorption amount of the porous carbon material under different pressures is recorded, and the nitrogen adsorption isotherm is drawn according to the nitrogen adsorption amount; The BET equation was used to fit the nitrogen adsorption isotherm. The BET equation is as follows: ； in, is the pressure of nitrogen; is the saturated vapor pressure of nitrogen; is the volume of nitrogen adsorbed under pressure; is the volume of gas required for adsorption by a single layer of porous carbon material; is the BET constant, which reflects the interaction between the adsorption layer and the adsorbed gas; Perform linear regression on the linear part of the BET equation to determine Value and value; according to Calculate the specific surface area of ​​porous carbon materials: ； in, is Avogadro's constant, is the effective cross-sectional area of ​​the nitrogen molecule; is the molar volume of nitrogen gas under standard conditions.

3. The method for evaluating the performance of a lithium-ion battery negative electrode porous carbon material according to claim 2, characterized in that: Based on the principle of capillary action, the total pore volume of the porous carbon material is measured; a low-viscosity liquid medium is selected and the porous carbon material is immersed in a liquid medium with a volume of in a liquid medium, after the porous carbon material is completely immersed in the liquid medium, ultrasonically oscillating the liquid medium, and stopping the ultrasonic oscillation when no bubbles are generated in the liquid medium; Take out the porous carbon material after infiltration from the liquid medium and obtain the remaining liquid medium volume ; Calculate the total pore volume of porous carbon materials : ; is the total volume of the liquid medium, and the total pore volume of the porous carbon material is measured multiple times and the average value is taken.

4. The method for evaluating the performance of a lithium-ion battery negative electrode porous carbon material according to claim 3, characterized in that: Improve the dynamic fluid method to measure the average pore size of porous carbon materials; dry the porous carbon materials, remove the liquid and gas inside, measure and record the cross-sectional area of ​​the porous carbon materials and length L; The porous carbon material is completely immersed in the driving liquid in the container, and a liquid inlet and a liquid outlet are respectively arranged above and below the container, and a pressure sensor and a flow meter are arranged at the liquid inlet and the liquid outlet to measure the pressure difference and flow rate of the driving liquid; Apply different pressures to the inlet and outlet of the container. The pressure difference between the inlet and outlet is ;Measure the flow rate of the driving liquid through the sample ; Change the pressure difference in sequence , and repeatedly measure and record the driving liquid flow rate through the sample under different pressure conditions ; According to Darcy's law, the flow rate is established Pressure difference Relationship: ； in, is the permeability, To drive the liquid viscosity; By the Kozeny-Carman equation, the permeability Equivalent pore size to porous carbon materials The following relationship exists: ； in, is the porosity, is the Kozeny constant, reflecting the shape and tortuosity of the pore; Solving for the equivalent pore size of porous carbon materials : ； Equivalent aperture It is the average pore size of the porous carbon material.

5. The method for evaluating the performance of a lithium-ion battery negative electrode porous carbon material according to claim 4, characterized in that: The graphitization degree of porous carbon materials is measured based on Raman spectroscopy technology. The surface of the porous carbon materials is polished, and a Raman spectrometer is used to scan the sample and select an appropriate laser wavelength to collect Raman spectral data. Analyze the characteristic peaks of the Raman spectrum, wherein the characteristic peaks of the Raman spectrum include a D peak and a G peak, and the integrated intensity ratio of the D peak and the G peak of the characteristic peak of the Raman spectrum is , is the integrated intensity of the D peak, is the integrated intensity of the G peak; a quantitative characterization model for the graphitization degree of porous carbon materials is established; Considering the size of graphite crystallites in porous carbon materials The influence on Raman spectroscopy is introduced by the Tuinstra-Koenig formula: ； in, is a constant related to the laser wavelength. By fitting the Raman spectral data of a large number of samples with known graphitization degrees, Quantitative relationship with graphitization degree: ； Among them, a, b, and c are fitting parameters obtained through experiments on carbon materials; The porous carbon material is tested by Raman spectroscopy to obtain the integrated intensity ratio R of the D peak and the G peak. The R value is substituted into the quantitative characterization model of graphitization degree to calculate the graphitization degree G of the porous carbon material.

6. The method for evaluating the performance of a lithium-ion battery negative electrode porous carbon material according to claim 5, characterized in that: Electrochemical impedance spectroscopy (EIS) was used to test the electrochemical performance of porous carbon materials when applied to negative electrodes of lithium-ion batteries. The porous carbon materials to be tested were prepared into battery electrodes using a three-electrode system, with the porous carbon materials as working electrodes, lithium sheets as counter electrodes, and silver chloride as reference electrodes. Connect the assembled battery to the electrochemical workstation, set the EIS parameters, set the frequency range, AC excitation intensity and test points; When the battery is in a stable state, a sinusoidal AC excitation signal is applied to the battery, and the signal is scanned within the set frequency range to measure the corresponding signal of the battery. That is, the battery impedance at different frequencies is calculated based on the changes in the battery current and voltage. At each frequency point, the corresponding electrical signal of the battery is automatically recorded by the electrochemical workstation, and the EIS spectrum of the battery is obtained after data acquisition; Analyze the EIS spectrum and plot the collected data into an EIS spectrum, wherein the EIS spectrum includes a Nyquist diagram and a Bode diagram; According to the characteristics of the EIS spectrum, an equivalent circuit model is set, wherein the equivalent circuit model includes a Randles circuit and a Voigt circuit; the EIS data is fitted using the software of the electrochemical workstation to obtain the parameter values ​​of each component in the equivalent circuit; According to the parameter values ​​obtained by equivalent circuit fitting, the key performance indicators of the battery are calculated to obtain the electrochemical properties of the porous carbon material when applied to the negative electrode of the lithium-ion battery, which include ohmic resistance , Charge transfer resistance , double layer capacitor and diffusion coefficient .

7. The method for evaluating the performance of a lithium-ion battery negative electrode porous carbon material according to claim 6, characterized in that: Construct a two-dimensional matrix of physical properties and electrochemical properties of porous carbon materials, and calculate the correlation between physical performance indicators and electrochemical performance indicators through the Pearson correlation coefficient matrix; According to the correlation coefficient matrix , analyze the correlation between the physical performance indicators and electrochemical performance indicators of porous carbon materials: when When The physical performance index and There is a strong correlation between the electrochemical performance indicators; when When The physical performance index and There is a moderate correlation between the electrochemical performance indicators; when When The physical performance index and There is a weak correlation between the electrochemical performance indicators.

8. A performance evaluation system for a lithium-ion battery negative electrode porous carbon material, which is implemented based on a performance evaluation method for a lithium-ion battery negative electrode porous carbon material according to any one of claims 1 to 7, characterized in that: include: Material acquisition module, physical property calculation module, electrochemical property calculation module, correlation calculation module and radar chart scoring module; The material acquisition module is used to obtain the porous carbon material for the negative electrode of the lithium-ion battery; The physical property measurement module is used to measure the physical properties of the porous carbon material, including specific surface area, total pore volume, average pore diameter and degree of graphitization; The specific surface area of ​​porous carbon materials was measured based on nitrogen adsorption isotherms and BET theory; Based on the principle of capillary action, the total pore volume of porous carbon materials is measured; Improved dynamic fluid method to measure the average pore size of porous carbon materials; Measuring the graphitization degree of porous carbon materials based on Raman spectroscopy; The electrochemical performance calculation module is used to test the electrochemical performance of the porous carbon material, and adopts electrochemical impedance spectroscopy (EIS) to test the electrochemical performance of the porous carbon material when it is applied to the negative electrode of a lithium-ion battery, and obtains the ohmic resistance, charge transfer resistance, double-layer capacitance and diffusion coefficient of the porous carbon material through the electrochemical impedance spectroscopy (EIS) test; The correlation calculation module is used to construct a two-dimensional matrix of physical properties and electrochemical properties of porous carbon materials, and calculate the correlation between physical performance indicators and electrochemical performance indicators through the Pearson correlation coefficient; The radar chart scoring module is used to construct a radar chart of the physicochemical performance indicators of the porous carbon material, display the physical and electrochemical performance scores of the porous carbon material, and evaluate the comprehensive performance of the porous carbon material according to the area of ​​the radar chart.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method for evaluating the performance of a porous carbon material for a negative electrode of a lithium ion battery according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for evaluating the performance of a porous carbon material for a negative electrode of a lithium ion battery according to any one of claims 1 to 7 are implemented.

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