Battery soaking degree judgment method, judgment device, electronic device and storage medium

Abstract

The present invention discloses a method for judging the degree of battery infiltration, including: obtaining impedance spectrum data of a battery to be tested at multiple different times; establishing an equivalent circuit model based on the impedance spectrum data, wherein the equivalent circuit model includes a transmission line model; obtaining multiple equivalent capacitance values ​​corresponding to multiple different times in the transmission line model according to the equivalent circuit model; judging whether the similarity of the multiple equivalent capacitance values ​​is within the similarity requirement range, if so, the battery to be tested is completely infiltrated, if not, the battery is not completely infiltrated. By adopting the above technical scheme, the degree of battery infiltration can be accurately judged without destroying the battery structure, the changes in the internal state of the battery can be accurately analyzed, the accuracy of judging the degree of battery infiltration can be improved, the sensitivity of testing and judgment can be improved, the accuracy and reliability of judgment can be improved, the judgment cost can be reduced, the efficiency of production detection can be improved, and the real-time nature of judging the degree of infiltration can be improved. A battery infiltration degree judgment device, an electronic device and a storage medium are also disclosed.

Description

Technical Field

[0001] The present invention belongs to the field of batteries and relates to a method for determining the degree of battery infiltration, a device for determining the degree of battery infiltration, an electronic device and a computer-readable storage medium. Background Art

[0002] As the application demand for lithium-ion batteries in fields such as electric vehicles and renewable energy continues to grow, the performance requirements for batteries are also increasing. During the manufacturing process of batteries, the degree of electrolyte infiltration has an important impact on its performance, directly affecting the electrochemical reaction efficiency and overall life of the battery. Therefore, accurately judging the degree of battery infiltration has become a key step in the battery production process. At present, the detection technology of the degree of infiltration of lithium-ion batteries has made many advances, but there are still some challenges and limitations. Traditional battery disassembly technology can intuitively display the infiltration conditions inside the battery, but this destructive method is not suitable for real-time detection on the production line.

[0003] Existing technologies usually use methods such as acoustic wave detection, infrared imaging and magnetic resonance imaging to evaluate the degree of battery infiltration. However, these methods have some defects in sensitivity, quantitative analysis ability and equipment complexity.

[0004] Acoustic wave detection is a method to evaluate the wetting state through the propagation characteristics of sound waves in the battery. Acoustic wave detection can provide information on changes in the internal structure of the battery, but its sensitivity is relatively low and it is difficult to capture tiny changes in the electrochemical interface. In addition, the results of acoustic wave detection are easily interfered by external noise, affecting the accuracy of detection.

[0005] Infrared imaging technology (such as Fourier transform infrared spectroscopy) detects the infrared absorption characteristics of the internal materials of the battery to infer the infiltration of the electrolyte. Infrared imaging mainly focuses on molecular vibration and chemical bond information, and can detect the distribution of chemical components, but it is difficult to directly provide changes in electrochemical performance. In addition, infrared detection is limited in quantitative analysis capabilities and can usually only provide qualitative or semi-quantitative information.

[0006] Magnetic resonance imaging (such as nuclear magnetic resonance) is a method for detecting the internal structure of lithium-ion batteries, but it mainly focuses on molecular motion and chemical environment and cannot directly reflect electrochemical performance parameters. Magnetic resonance detection equipment is expensive, complicated to operate, and requires high sample preparation, which is not suitable for rapid detection in production environments.

[0007] The existing technology detects the degree of battery infiltration through methods such as acoustic wave detection, infrared imaging and magnetic resonance imaging. It is about how to accurately judge the degree of battery infiltration without destroying the battery structure, accurately analyze the changes in the internal state of the battery, improve the accuracy of judging the degree of battery infiltration, and improve the sensitivity of testing and judgment. However, the process of solving the problem of judging the degree of infiltration is cumbersome, and the problem of improving the accuracy of infiltration judgment has not been effectively solved. Summary of the invention

[0008] The purpose of the present invention is to solve the problem that the process of judging the degree of infiltration is complicated and to improve the accuracy of the infiltration judgment.

[0009] In a first aspect, the present invention provides a method for determining the degree of battery infiltration, comprising: obtaining impedance spectrum data of a battery to be tested at multiple different times; establishing an equivalent circuit model based on the impedance spectrum data, wherein the equivalent circuit model includes a transmission line model; obtaining multiple equivalent capacitance values ​​corresponding to multiple different times in the transmission line model according to the equivalent circuit model; determining whether the degree of similarity of the multiple equivalent capacitance values ​​is within a similarity requirement range, if so, the battery to be tested is completely infiltrated, and if not, the battery is incompletely infiltrated.

[0010] By adopting the above technical scheme, the degree of battery infiltration can be accurately judged without destroying the battery structure, the changes in the internal state of the battery can be accurately analyzed, the accuracy of judging the degree of battery infiltration can be improved, the sensitivity of testing and judgment can be improved, the cumbersome process of judging the degree of infiltration can be solved, and the accuracy of infiltration judgment can be improved.

[0011] According to another specific embodiment of the present invention, an equivalent circuit model is used to analyze impedance spectrum data, which includes: a contact impedance module, an ohmic internal resistance module, an interface impedance module and a transmission line model, wherein the contact impedance module, the ohmic resistance, the interface impedance module and the transmission line model are connected in series.

[0012] Among them, the contact impedance module represents the contact resistance and internal inductance between the test device and the battery to be tested, the ohmic internal resistance module represents the ohmic internal resistance of the battery to be tested, the interface impedance module represents the contact resistance and interface capacitance between the electrode plate and the electrolyte interface, and the transmission line model represents the charge transfer of the porous electrode inside the battery to be tested.

[0013] According to another specific embodiment of the present invention, the contact impedance module includes a first resistor and a first inductor, which are connected in parallel; the ohmic internal resistance module includes an ohmic resistor; and the interface impedance module includes a second resistor and a constant phase element, which are connected in parallel.

[0014] According to another specific embodiment of the present invention, the transmission line model is a transmission line model equivalent reference model.

[0015] According to another specific embodiment of the present invention, obtaining impedance spectrum data of the battery to be tested at multiple different times includes: inputting a disturbance current with a changing frequency, measuring the impedance spectrum of the battery to be tested at multiple different times, and obtaining impedance spectrum data at multiple different times; wherein, the frequency range of the disturbance current is 0.5-50000Hz, the current value of the disturbance current is 1200mA, and the time interval between different times is 630s-6300s.

[0016] According to another specific embodiment of the present invention, establishing an equivalent circuit model based on impedance spectrum data includes: establishing an equivalent circuit initial model, fitting the impedance spectrum data according to the equivalent circuit initial model to obtain a fitting result, updating the model parameters of the equivalent circuit initial model according to the equivalent circuit initial model and the fitting result, until the fitting result meets the preset fitting conditions, and determining the equivalent circuit initial model with the updated model parameters as the equivalent circuit model.

[0017] According to another specific embodiment of the present invention, the impedance spectrum data includes Nyquist data and / or Bode data.

[0018] In a second aspect, the present invention also provides a battery infiltration degree judgment device, including: a data acquisition module, used to obtain impedance spectrum data of a battery to be tested at multiple different times; a model establishment module, used to establish an equivalent circuit model based on the impedance spectrum data, the equivalent circuit model includes a transmission line model; an equivalent capacitance determination module, used to obtain multiple equivalent capacitance values ​​corresponding to multiple different times in the transmission line model according to the equivalent circuit model; an infiltration judgment module, used to judge whether the similarity of multiple equivalent capacitance values ​​is within the similarity requirement range, if so, the battery to be tested is completely infiltrated, if not, the battery is incompletely infiltrated.

[0019] By adopting the above technical scheme, the degree of battery infiltration can be accurately judged without destroying the battery structure, the changes in the internal state of the battery can be accurately analyzed, the accuracy of judging the degree of battery infiltration can be improved, the sensitivity of testing and judgment can be improved, the cumbersome process of judging the degree of infiltration can be solved, and the accuracy of infiltration judgment can be improved.

[0020] In a third aspect, an electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned method for determining the degree of battery infiltration when executing the computer program.

[0021] By adopting the above technical scheme, the degree of battery infiltration can be accurately judged without destroying the battery structure, the changes in the internal state of the battery can be accurately analyzed, the accuracy of judging the degree of battery infiltration can be improved, the sensitivity of testing and judgment can be improved, the cumbersome process of judging the degree of infiltration can be solved, and the accuracy of infiltration judgment can be improved.

[0022] In a fourth aspect, a computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the above-mentioned method for determining the degree of battery infiltration is implemented.

[0023] By adopting the above technical scheme, the degree of battery infiltration can be accurately judged without destroying the battery structure, the changes in the internal state of the battery can be accurately analyzed, the accuracy of judging the degree of battery infiltration can be improved, the sensitivity of testing and judgment can be improved, the cumbersome process of judging the degree of infiltration can be solved, and the accuracy of infiltration judgment can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The flow chart of the method for determining the battery soaking degree in the embodiment of the present invention is shown as follows: Figure 1 ;

[0025] Figure 2 The flow chart of the method for determining the battery soaking degree in the embodiment of the present invention is shown as follows: Figure 2 ;

[0026] Figure 3 The flow chart of the method for determining the battery soaking degree in the embodiment of the present invention is shown as follows: Figure 3 ;

[0027] Figure 4 A schematic diagram showing the structure of a battery soaking degree judgment device according to an embodiment of the present invention Figure 1 ;

[0028] Figure 5 A schematic diagram showing the structure of a battery soaking degree judgment device according to an embodiment of the present invention Figure 2 ;

[0029] Figure 6 A schematic diagram showing the structure of a battery soaking degree judgment device according to an embodiment of the present invention Figure 3 ;

[0030] Figure 7 A schematic diagram showing the structure of an electronic device in an embodiment of the present invention is shown;

[0031] Figure 8 A schematic diagram of the circuit structure of an equivalent circuit model in an embodiment of the present invention is shown;

[0032] Fig. 9 A schematic diagram of the circuit structure of a transmission line model in an embodiment of the present invention is shown;

[0033] Fig.10 An impedance spectrum data diagram according to an embodiment of the present invention is shown;

[0034] Fig.11 A data diagram of equivalent capacitance values ​​in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0035] The following specific embodiments illustrate the implementation of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this implementation. On the contrary, the purpose of introducing the invention in conjunction with the implementation is to cover other options or modifications that may extend based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will include many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0036] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0038] Electrochemical Impedance Spectroscopy (EIS) is a technique used to study and analyze electrochemical systems. EIS applies a small-amplitude sinusoidal AC voltage or current to the electrochemical system and measures the resulting AC current or voltage response. Since the applied signal amplitude is very small and does not cause steady-state changes in the system, it can be assumed that the system is in a steady state at all frequencies. Tests are performed at different frequencies and the impedance of the system is recorded. Impedance is a complex impedance, including real resistance and imaginary reactance. By changing the frequency of the perturbation current, a spectrum of the impedance of the battery to be tested as it changes with frequency can be obtained, which is the electrochemical impedance spectrum.

[0039] First, refer to Figure 1 The present invention provides a method for determining the degree of battery infiltration, comprising:

[0040] S01: Obtain impedance spectrum data of the battery to be tested at multiple different times.

[0041] Acquiring impedance spectrum data of the battery to be tested at multiple different times includes: measuring the impedance spectrum of the battery to be tested at multiple different times to obtain impedance spectrum data at multiple different times.

[0042] S02: Establish an equivalent circuit model based on the impedance spectrum data, and the equivalent circuit model includes a transmission line model.

[0043] The equivalent circuit model is a circuit model used to simulate the impedance behavior of the electrochemical system. According to the actual impedance behavior of the electrochemical system, the complex electrochemical process is decomposed into a combination of basic elements in the circuit. Each circuit element represents a specific electrochemical process in the system. For example, the resistor represents the electrolyte resistance, charge transfer resistance, etc. The capacitor represents the double layer capacitance, electrode capacitance, etc. The inductor represents the inductive effect in the circuit, such as electromagnetic induction. The constant phase element (CPE) is used to simulate the deviation of the capacitance behavior in the actual system. The specific equivalent circuit model will be explained in detail later. The transmission line model (TLM) is an electrochemical model used to describe the charge or material transfer process in complex media (such as porous materials). The transmission line model represents the charge transfer of the porous electrode inside the battery to be tested. The transmission line model can simulate the behavior of the electrolyte transport and diffusion in the pores of the electrode material.

[0044] S03: Obtaining a plurality of equivalent capacitance values ​​corresponding to a plurality of different moments in the transmission line model according to the equivalent circuit model.

[0045] like Fig. 9 As shown, Fig. 9 The figure is a schematic diagram of a transmission line model circuit structure in an embodiment of the present invention, corresponding to three constant phase elements. Each moment corresponds to an equivalent capacitance value in a transmission line model, and the equivalent capacitance value refers to the total equivalent capacitance value of the circuit structure diagram.

[0046] S04: Determine whether the similarity of multiple equivalent capacitance values ​​is within the similarity requirement range. If so, execute S05-1: The battery to be tested is fully soaked. If not, execute S05-2: The battery is not fully soaked. The similarity requirement range refers to the range in which multiple equivalent capacitance values ​​tend to be consistent. When the similarity of multiple equivalent capacitance values ​​is within the similarity requirement range, it is considered that multiple equivalent capacitance values ​​tend to be consistent. For example, the similarity requirement range is that the similarity of multiple equivalent capacitance values ​​is 95%-105% of the average value of multiple equivalent capacitance values. That is, the equivalent capacitance values ​​at multiple different times are all within the range of 95%-105% of the average value of multiple equivalent capacitance values. When the similarity of multiple equivalent capacitance values ​​is within this similarity requirement range, it is considered that the equivalent capacitance value is stable and the battery is fully soaked. Preferably, the similarity requirement range is that the similarity of multiple equivalent capacitance values ​​is 98%-102% of the average value of multiple equivalent capacitance values. That is, the equivalent capacitance values ​​at multiple different times are all within the range of 98%-102% of the average value of multiple equivalent capacitance values. Within this range, it is considered that the equivalent capacitance value is constant, the battery is fully infiltrated, and the judgment error is reduced. The infiltration process of the battery refers to the gradual penetration of the electrolyte into the internal structure of the battery, especially into the pores and interfaces of the electrode material. When the electrolyte completely infiltrates the electrode surface and the microporous structure, the contact between the electrode and the electrolyte interface will be more sufficient, so that the capacitance characteristics of the interface tend to be stable. In the electrochemical impedance spectroscopy test, the equivalent capacitance value is mainly determined by the contact state between the electrolyte and the electrode interface. When the electrolyte infiltration is incomplete, the equivalent capacitance value at different times will fluctuate due to the uneven interface contact. The transmission line model is used to simulate electrode materials with porous structures, and the transmission line model is used to simulate the transmission process of the electrolyte in the internal structure of the electrode. The degree of similarity of the equivalent capacitance values ​​measured at different times can reflect the penetration state of the electrolyte in the electrode pores. When the electrolyte completely infiltrates the pores and surface of the electrode, the charge distribution on the interface will tend to be stable, and the changes in the interface resistance and capacitance will become very small. When the electrolyte is evenly distributed in the electrode structure, the equivalent capacitance values ​​in the transmission line model tend to be consistent, indicating that the interface and pores of the battery have been fully filled with the electrolyte.

[0047] By adopting the above technical solution, the battery infiltration degree can be accurately judged without destroying the battery structure, the changes in the internal state of the battery can be accurately analyzed, the accuracy of the judgment of the battery infiltration degree can be improved, the sensitivity of testing and judgment can be improved, the complicated process of judging the infiltration degree can be solved, and the accuracy of infiltration judgment can be improved. The above technical solution can accurately analyze the internal state of the battery according to the impedance spectrum data of the electrochemical impedance spectrum, and can accurately identify the changes in the equivalent capacitance value at different times according to the infiltration judgment result obtained by the equivalent circuit model. When the similarity of the equivalent capacitance values ​​at multiple different times is within the similar requirement range, it can be accurately and sensitively identified, with high reliability. Compared with testing methods such as magnetic resonance, the judgment cost is low, the operation is simple, the detection is convenient, the production efficiency is improved, and it can be detected in real time when the infiltration is completed.

[0048] According to another specific embodiment of the present invention, Figure 8 As shown, Figure 8 The schematic diagram of the circuit structure of the equivalent circuit model in the embodiment of the present invention is used to analyze the impedance spectrum data, which includes: a contact impedance module, an ohmic internal resistance module, an interface impedance module and a transmission line model. The contact impedance module, the ohmic resistance, the interface impedance module and the transmission line model are connected in series, wherein the contact impedance module represents the contact resistance and internal inductance between the test device and the battery to be tested, the ohmic internal resistance module represents the ohmic internal resistance of the battery to be tested, the interface impedance module represents the contact resistance and interface capacitance of the electrode plate and the electrolyte interface, and the transmission line model represents the charge transfer of the porous electrode inside the battery to be tested. The equivalent circuit model can accurately decompose the overall impedance of the battery into the impedance of each independent electrochemical process. By adopting the above technical solution, an equivalent circuit model can be established, and it can accurately determine whether the battery has reached a fully infiltrated state, intuitively understand the impedance characteristics of each part of the battery, and facilitate the analysis of the key factors affecting the battery performance.

[0049] According to another specific embodiment of the present invention, Figure 8, the contact impedance module includes a first resistor R1 and a first inductor L1, and the first resistor R1 and the first inductor L1 are connected in parallel. The first resistor R1 represents the contact resistance between the test device and the battery to be tested, which is caused by the incomplete contact between the test device (for example, the probe) and the battery surface or the impedance between the materials. The first inductor L1 represents the inductive characteristics between the test device and the battery due to the connecting wire and the internal structure, that is, the impedance caused by the magnetic field generated by the current flow. The ohmic internal resistance module includes an ohmic resistor R2, which is used to simulate the resistance characteristics of the internal materials of the battery, that is, the direct resistance between the positive electrode, negative electrode, electrolyte and other materials of the battery. The ohmic resistance represents the material resistance of the battery itself and is not affected by the frequency. The ohmic internal resistance module is mainly used to represent the resistance of the solid conductive material (such as the current collector and electrode material) inside the battery. The interface impedance module includes a second resistor R3 and a constant phase element CPE1, and the second resistor R3 and the constant phase element CPE1 are connected in parallel. The contact impedance module can effectively simulate the composite impedance characteristics caused by poor contact and structural inductance during the actual test process, which helps to accurately analyze the connection effect between the battery and the external device. The second resistor R3 represents the contact resistance of the electrode plate and the electrolyte interface, that is, the impedance caused by the ion transmission barrier between the electrode material and the electrolyte. The constant phase element CPE1 is used to represent non-ideal capacitance behavior, especially the deviation from the ideal capacitance characteristics caused by the interface roughness or porous structure at the electrode and electrolyte interface. The existence of the constant phase element CPE1 enables the module to more realistically reflect the frequency dependence and nonlinear impedance characteristics of the electrode and electrolyte interface in actual work, which is conducive to accurately analyzing the interface performance and interface contact quality. By adopting the above technical solution, an equivalent circuit model can be established based on the impedance spectrum data to more accurately analyze the electrochemical characteristics inside the battery.

[0050] According to another specific embodiment of the present invention, the transmission line model is a transmission line model equivalent benchmark model. The Transmission Line Model Equivalent Base (Tlmeb) is a benchmark model defined in the transmission line model, which is used to simplify and standardize the model and is used to simulate the diffusion behavior in the distributed impedance system. It is particularly suitable for the diffusion impedance in batteries and electrochemical systems, and represents the Brownian diffusion effect under the transmission line model. In electrochemistry, the transmission line model usually represents the mass transfer impedance at the interface between the electrode and the electrolyte, such as the ion diffusion inside the electrode or the adsorption phenomenon on the electrode surface. The Tlmeb model can capture the impedance changes of the diffusion process at different frequencies, and is suitable for describing the complex diffusion and charge transfer processes in battery materials. The equivalent capacitance value of the transmission line model no longer changes significantly, that is, whether the similarity of multiple equivalent capacitance values ​​is within the similarity requirement range, indicating that the diffusion impedance of the battery to be tested no longer changes significantly, and the battery to be tested is fully infiltrated. Fig. 9As shown, the Tlmeb model includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a second constant phase element CPE2, a third constant phase element CPE3, and a fourth constant phase element CPE4, and the connection relationship is as shown in FIG. Fig. 9 shown.

[0051] According to another specific embodiment of the present invention, Figure 2 As shown, S01: obtaining impedance spectrum data of the battery under test at multiple different times includes: S011: inputting a disturbance current with a changing frequency. S012: measuring the impedance spectrum of the battery under test at multiple different times. S013: obtaining impedance spectrum data at multiple different times.

[0052] Among them, the frequency range of the perturbation current is 0.5-50000Hz, the current value of the perturbation current is 1200mA, and the time interval at different times is 630s-6300s. By setting the frequency range of the perturbation current to 0.5-50000Hz, the response frequency bands of different electrochemical processes inside the battery can be fully covered. The low frequency band can reflect the charge transfer and diffusion characteristics of the battery, while the high frequency band can reveal the contact resistance and the intrinsic characteristics of the electrode material. This comprehensive frequency coverage enables the impedance spectrum data to more accurately reflect the overall electrochemical state of the battery. The perturbation current of 1200mA can provide sufficient signal strength to improve the measurement accuracy while maintaining non-destructive testing. This makes the acquisition of impedance spectrum data more stable and reliable, thereby improving the accuracy and resolution of the measurement results.

[0053] The adoption of the above technical solution can more accurately reflect the overall electrochemical state of the battery and improve the accuracy of infiltration judgment.

[0054] In some embodiments, the equivalent circuit model is fitted to the impedance spectrum data using RelaxIS 3 software.

[0055] According to another specific embodiment of the present invention, Figure 3 As shown, S02: establishing an equivalent circuit model based on impedance spectrum data includes: S021: establishing an equivalent circuit initial model. S022: fitting the impedance spectrum data according to the equivalent circuit initial model to obtain a fitting result. S023: updating the model parameters of the equivalent circuit initial model according to the equivalent circuit initial model and the fitting result, until the fitting result meets the preset fitting condition, and determining the equivalent circuit initial model with the updated model parameters as the equivalent circuit model. The model parameters specifically include the values ​​of the inductance, resistance, capacitance and constant phase elements in the equivalent circuit initial model, as well as the circuit structure or connection relationship of the inductance, resistance, capacitance and constant phase elements.

[0056] In some embodiments, the impedance spectrum data is fitted according to the initial model of the equivalent circuit to obtain a fitting result using a nonlinear least squares method.

[0057] Specifically, an equivalent circuit initial model is established according to the electrochemical reaction inside the battery, and the equivalent circuit initial model and the impedance spectrum data are substituted into the RelaxIS3 software to obtain a fitting result. The fitting result is a specific numerical value, representing the matching degree of the equivalent circuit initial model to the impedance spectrum data. In some embodiments, the fitting result is, for example, 0.985. It is determined whether the fitting result meets the preset fitting condition, and the preset fitting condition is, for example, that the fitting result is greater than 0.95. If the fitting result meets the preset fitting condition, the equivalent circuit initial model is determined as the equivalent circuit model. If the fitting result does not meet the preset fitting condition, the model parameters of the equivalent circuit initial model are updated, for example, the circuit structure, connection relationship or value of the inductance, resistance, capacitance and constant phase element of the equivalent circuit initial model are updated, and the equivalent circuit initial model and the impedance spectrum data after the updated model parameters are substituted into the RelaxIS3 software to obtain a fitting result, and it is repeated to determine whether the fitting result meets the preset fitting condition, update the model parameters of the equivalent circuit initial model, and substitute the equivalent circuit initial model and the impedance spectrum data after the updated model parameters into the RelaxIS3 software to obtain a fitting result, until the fitting result meets the preset fitting condition.

[0058] By adopting the above technical solution, an equivalent circuit model that conforms to the actual electrochemical reaction situation can be obtained, and the equivalent circuit model can simulate the actual situation of the impedance spectrum data.

[0059] In some embodiments, verifying whether the equivalent circuit model is valid can also be performed using RelaxIS 3 software. The steps include: selecting impedance spectrum data and importing it into Relax-IS3 software. Clicking Kramers-Kronig test to obtain a KK transformation spectrum. Verifying the difference between the KK transformation spectrum and the original spectrum. By comparing the difference between the KK transformation spectrum and the original spectrum, determine whether the equivalent circuit model is valid.

[0060] In some embodiments, it also includes judging whether the equivalent circuit model has practical significance. For example, judging whether the physical meaning of the fitting parameters meets the experimental conditions. For another example, judging whether the equivalent model can accurately describe the characteristics in the impedance spectrum. Further electrochemical interpretation or optimization of the fitting results, such as adding or deleting elements to improve the fitting accuracy.

[0061] According to another specific embodiment of the present invention, the impedance spectrum data includes Nyquist data and / or Bode data. Fig.10 As shown, Fig.10 : is an impedance spectrum data diagram in an embodiment of the present invention, and the impedance spectrum data diagram is a Nyquist data diagram. Fig.10In the figure, the ordinate is the imaginary part of the impedance spectrum data, the abscissa is the real part of the impedance spectrum data, and the projection of the peak on the abscissa represents the size of the ohmic internal resistance. In the figure, 1, 101, 201, 301, 401, and 501 represent the number of tests, which are the 1st, 101st, 201st, 301st, 401st, and 501st tests, respectively. As can be seen from the figure, from 1 to 501 tests, as the tests continue, the ohmic internal resistance of the battery continues to decrease. As the degree of infiltration continues to increase, the electrolyte infiltration continues to be complete, and the ohmic internal resistance shows a continuous decrease, which is consistent with the principle of battery infiltration.

[0062] In some embodiments, the method further includes: analyzing characteristic regions and shapes of the impedance spectrum data, such as the behavior of high frequency, medium frequency and low frequency regions, to identify the contribution of various processes. For example, the semicircle in the Nyquist plot usually represents the charge transfer resistance and the double layer capacitance, while the straight line portion may be associated with the Warburg impedance, reflecting the diffusion process.

[0063] Next, a more specific embodiment of a method for judging the degree of battery infiltration is introduced. S01: Obtain impedance spectrum data of the battery to be tested at multiple different times. S011: Input a disturbance current with varying frequency. S012: Measure the impedance spectrum of the battery to be tested at multiple different times. S013: Obtain impedance spectrum data at multiple different times:. Among them, the frequency range of the disturbance current is 0.5-50000Hz, the current value of the disturbance current is 1200mA, and the time interval at different times is 630s. Specifically, it takes 30s to collect impedance spectrum data, wait for 600s, and test the open circuit voltage of the battery to be tested during the 600s waiting process. The time interval at different times is 630s, which can prevent the test device from overloading due to continuous operation, and can also prevent the amount of data from being too large and reduce the amount of data.

[0064] S02: Establishing an equivalent circuit model based on impedance spectrum data includes: S021: Establishing an initial model of an equivalent circuit. S022: Obtaining a preset model result. S023: Fitting the impedance spectrum data according to the initial model of the equivalent circuit to obtain a fitting result. S024: Obtaining a similarity result between the fitting result and the preset model result. S025: According to the initial model of the equivalent circuit, the fitting result and the similarity result, updating the model parameters of the initial model of the equivalent circuit until the similarity meets the preset similarity condition, and determining the initial model of the equivalent circuit with the updated model parameters as the equivalent circuit model.

[0065] S03: Obtaining a plurality of equivalent capacitance values ​​corresponding to a plurality of different moments in the transmission line model according to the equivalent circuit model.

[0066] S04: Determine whether the similarity of the multiple equivalent capacitance values ​​is within the similarity requirement range, if so, execute S05-1: the battery to be tested is fully soaked. If not, execute S05-2: the battery is not fully soaked.

[0067] Fig.11 It is the equivalent capacitance value data graph in the embodiment of the present invention. It can be seen that the equivalent capacitance values ​​corresponding to different times 1-269 times are constantly increasing. The equivalent capacitance value increases significantly within 0-6 hours. The equivalent capacitance value obtained after 270 times (corresponding to 40 hours) does not change much and tends to be consistent. The similarity of multiple equivalent capacitance values ​​is within the similar requirement range, indicating that the double-layer capacitance generated by the positive and negative electrode materials of the battery is stable, the equivalent capacitance value temperature of the transmission line model, and the battery is completely wetted.

[0068] Second, reference Figure 4 The present invention also provides a battery infiltration degree judgment device 100, including: a data acquisition module 101, used to obtain impedance spectrum data of a battery to be tested at multiple different times; a model establishment module 102, used to establish an equivalent circuit model based on the impedance spectrum data, the equivalent circuit model includes a transmission line model; an equivalent capacitance determination module 103, used to obtain multiple equivalent capacitance values ​​corresponding to multiple different times in the transmission line model according to the equivalent circuit model; an infiltration judgment module 104, used to judge whether the similarity of multiple equivalent capacitance values ​​is within the similarity requirement range, if so, the battery to be tested is completely infiltrated, if not, the battery is not completely infiltrated.

[0069] By adopting the above technical scheme, the degree of battery infiltration can be accurately judged without destroying the battery structure, the changes in the internal state of the battery can be accurately analyzed, the accuracy of judging the degree of battery infiltration can be improved, the sensitivity of testing and judgment can be improved, the cumbersome process of judging the degree of infiltration can be solved, and the accuracy of infiltration judgment can be improved.

[0070] like Figure 5 As shown, the present invention also provides a battery infiltration degree judgment device 100, including: a disturbance current input module 105, used to input a disturbance current with a frequency change; an impedance spectrum test module 106, used to measure the impedance spectrum of the battery to be tested at multiple different times; and a data final acquisition module 107, used to obtain impedance spectrum data at multiple different times.

[0071] like Figure 6As shown, the present invention also provides a battery infiltration degree judgment device 100, including: an initial model establishment module 108, used to establish an equivalent circuit initial model. A preset model acquisition module 109, used to obtain a preset model result. A fitting module 110, used to fit the impedance spectrum data according to the equivalent circuit initial model to obtain a fitting result. A similarity acquisition module 111, used to obtain a similarity result between the fitting result and the preset model result. A model update module 112, used to update the model parameters of the equivalent circuit initial model according to the equivalent circuit initial model, the fitting result and the similarity result, until the similarity meets the preset similarity condition, and the equivalent circuit initial model with the model parameter updated is determined as the equivalent circuit model.

[0072] Thirdly, Figure 7 As shown, an electronic device 200 includes a memory 201, a processor 202, and a computer program stored in the memory 201 and executable on the processor 202. When the processor 202 executes the computer program, the above-mentioned battery infiltration degree judgment method is implemented.

[0073] By adopting the above technical scheme, the degree of battery infiltration can be accurately judged without destroying the battery structure, the changes in the internal state of the battery can be accurately analyzed, the accuracy of judging the degree of battery infiltration can be improved, the sensitivity of testing and judgment can be improved, the cumbersome process of judging the degree of infiltration can be solved, and the accuracy of infiltration judgment can be improved.

[0074] In a fourth aspect, a computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the above-mentioned method for determining the degree of battery infiltration is implemented.

[0075] By adopting the above technical scheme, the degree of battery infiltration can be accurately judged without destroying the battery structure, the changes in the internal state of the battery can be accurately analyzed, the accuracy of judging the degree of battery infiltration can be improved, the sensitivity of testing and judgment can be improved, the cumbersome process of judging the degree of infiltration can be solved, and the accuracy of infiltration judgment can be improved.

[0076] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable non-transient storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0077] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0078] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0079] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0080] Although the present invention has been illustrated and described with reference to certain preferred embodiments of the present invention, it should be understood by those skilled in the art that the above is a further detailed description of the present invention in conjunction with specific embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. Those skilled in the art may make various changes in form and details, including making several simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A method for determining the degree of battery infiltration, characterized in that: include: Obtain impedance spectrum data of the battery to be tested at multiple different times; Establishing an equivalent circuit model based on the impedance spectrum data, wherein the equivalent circuit model includes a transmission line model; Obtaining a plurality of equivalent capacitance values ​​corresponding to a plurality of different moments in the transmission line model according to the equivalent circuit model; It is determined whether the similarity of the multiple equivalent capacitance values ​​is within a similarity requirement range. If so, the battery to be tested is fully soaked; otherwise, the battery is not fully soaked.

2. The method for determining the battery soaking degree according to claim 1, characterized in that: The equivalent circuit model is used to analyze the impedance spectrum data, and includes: a contact impedance module, an ohmic internal resistance module, an interface impedance module and the transmission line model, wherein the contact impedance module, the ohmic resistance, the interface impedance module and the transmission line model are connected in series. Among them, the contact impedance module represents the contact resistance and internal inductance between the test device and the battery to be tested, the ohmic internal resistance module represents the ohmic internal resistance of the battery to be tested, the interface impedance module represents the contact resistance and interface capacitance between the electrode plate and the electrolyte interface, and the transmission line model represents the charge transfer of the porous electrode inside the battery to be tested.

3. The method for determining the battery soaking degree according to claim 2, characterized in that: The contact impedance module includes a first resistor and a first inductor, and the first resistor and the first inductor are connected in parallel; The ohmic internal resistance module includes an ohmic resistor; The interface impedance module includes a second resistor and a constant phase element, and the second resistor and the constant phase element are connected in parallel.

4. The method for determining the battery soaking degree according to claim 2, characterized in that: The transmission line model is a transmission line model equivalent benchmark model.

5. The method for determining the battery soaking degree according to claim 1, characterized in that: The obtaining of impedance spectrum data of the battery to be tested at multiple different times includes: Inputting a disturbance current with a changing frequency, measuring the impedance spectrum of the battery to be tested at multiple different times, and obtaining the impedance spectrum data at multiple different times; The frequency range of the disturbance current is 0.5-50000 Hz, the current value of the disturbance current is 1200 mA, and the time interval between the different moments is 630s-6300s.

6. The method for determining the battery soaking degree according to claim 1, characterized in that: The establishing of the equivalent circuit model based on the impedance spectrum data comprises: establishing an initial equivalent circuit model, fitting the impedance spectrum data according to the initial equivalent circuit model to obtain a fitting result, According to the equivalent circuit initial model and the fitting result, the model parameters of the equivalent circuit initial model are updated until the fitting result meets the preset fitting condition, and the equivalent circuit initial model with the model parameters updated is determined as the equivalent circuit model.

7. The method for determining the battery soaking degree according to claim 1, characterized in that: The impedance spectrum data includes Nyquist data and / or Bode data.

8. A battery soaking degree determination device, characterized in that: include: A data acquisition module is used to obtain impedance spectrum data of the battery to be tested at multiple different times; A model building module, used to build an equivalent circuit model based on the impedance spectrum data, wherein the equivalent circuit model includes a transmission line model; An equivalent capacitance determination module, used to obtain a plurality of equivalent capacitance values ​​corresponding to a plurality of different moments in the transmission line model according to the equivalent circuit model; The soaking judgment module is used to judge whether the similarity of the multiple equivalent capacitance values ​​is within the similarity requirement range. If so, the battery to be tested is fully soaked; if not, the battery is not fully soaked.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method for determining the battery wetness level according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for determining the battery wetness level according to any one of claims 1 to 7 is implemented.

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