Methods for determining polarization potential, methods and apparatus for measuring electrolyte ion transport number

Abstract

This application provides a method, apparatus, computer device, and storage medium for determining polarization potential. The method includes: acquiring current density change data obtained by performing constant potential polarization tests on a test battery pack at different polarization potentials; performing fitting processing on the current density change data to obtain fitting parameters corresponding to different polarization potentials; and determining the target polarization potential of the test battery pack based on the fitting parameters. This method can determine the optimal polarization potential of the test battery pack, supporting the acquisition of more accurate ion transport numbers. This application also provides a method, apparatus, computer device, and storage medium for testing electrolyte ion transport numbers. The method includes: acquiring forward polarization test data of the test battery pack; and determining the forward ion transport number of each test battery pack based on the forward polarization test data, wherein the forward polarization potential used in the forward polarization test is obtained by the polarization potential determination method. This method can obtain more accurate ion transport numbers.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method, apparatus, computer equipment, storage medium and computer program product for determining polarization potential, as well as a method, system, apparatus, computer equipment, storage medium and computer program product for testing electrolyte ion transport number. Background Technology

[0002] Ion transport number is a parameter used to evaluate ion migration ability. The electrolyte, as a crucial component of lithium-ion batteries, plays a role in ion transport between the positive and negative electrodes. For electrolytes, whether liquid or solid, transport number is a vital parameter for evaluating their ion transport capability. Testing the ion transport number of the electrolyte can predict battery performance. A higher ion transport coefficient is beneficial for reducing concentration polarization during charging and discharging, and is significant for improving the battery's power density and energy density.

[0003] In the field of electrolyte ion transport number testing, commonly used methods include constant potential polarization (also known as constant potential polarization). However, the method of testing ion transport number using constant potential polarization suffers from the problem of low accuracy in the test results.

[0004] Therefore, there is a need to provide a solution that can improve the accuracy of electrolyte ion transport number. Summary of the Invention

[0005] Therefore, it is necessary to provide a method, apparatus, computer equipment, storage medium, and computer program product for determining polarization potential that can improve the accuracy of electrolyte ion transport number, as well as a method, system, apparatus, computer equipment, storage medium, and computer program product for testing electrolyte ion transport number, in response to the above-mentioned technical problems.

[0006] Firstly, this application provides a method for determining polarization potential. The method includes:

[0007] Obtain current density variation data from constant potential polarization tests on the test battery pack with different polarization potentials;

[0008] The current density variation data is fitted to obtain the fitting parameters corresponding to different polarization potentials.

[0009] Based on the fitted parameters, the target polarization potential of the test battery pack is determined. The target polarization potential is used to maintain the test battery pack in a steady state under polarization.

[0010] In the technical solution of this application embodiment, the current density change data obtained by performing constant potential polarization tests on the test battery pack with different polarization potentials are fitted to obtain fitting parameters corresponding to different polarization potentials. Then, based on the fitting parameters, the target polarization potential that enables the test battery pack to maintain a steady state under polarization is determined. This process differs from the traditional method of using a universal fixed value for constant potential polarization testing. By fitting the current density change data corresponding to different polarization potentials, the target polarization potential that enables the test battery pack to maintain a steady state under polarization can be determined specifically. This allows for the targeted determination of the optimal polarization potential for the test battery pack and supports constant potential polarization testing using this target polarization potential, resulting in more accurate measured ion transference numbers.

[0011] In some embodiments, fitting the current density variation data to obtain fitting parameters includes:

[0012] Curve fitting was performed on the current density variation data to obtain the fitting parameters.

[0013] In the technical solution of this application embodiment, by performing curve fitting on the current density change data, the relationship between current density and time can be characterized simply and quickly, which facilitates the selection of target polarization potential.

[0014] In some embodiments, curve fitting is performed on the current density variation data to obtain fitting parameters, including:

[0015] Select target current density change data within a preset time range from the current density change data;

[0016] Linear regression fitting was performed on the target current density change data to obtain the linear regression fitting parameters.

[0017] In the technical solution of this application embodiment, by performing linear regression fitting on the current density change data within a preset time range, the linear regression fitting parameters can be obtained quickly and accurately.

[0018] In some embodiments, determining the target polarization potential of the test battery pack based on the fitted parameters includes:

[0019] The linear regression fitting parameters are compared with the preset linear coefficients;

[0020] Based on the comparison results and the preset polarization potential selection rules, the target polarization potential of the test battery pack is determined.

[0021] In the technical solution of this application embodiment, the target polarization potential of the test battery pack is determined by a preset linear coefficient and a preset polarization potential selection rule, which makes the determined target polarization potential more accurate and objective.

[0022] Secondly, this application also provides a method for testing the ion transport number of an electrolyte, the method comprising:

[0023] Obtain forward polarization test data for the test battery pack. The forward polarization test data includes test data obtained by performing electrochemical impedance spectroscopy and potentiostatic polarization tests on the test battery pack with forward polarization potential.

[0024] Based on the forward polarization test data, the forward ion migration number of each test battery pack was determined;

[0025] The positive polarization potential is obtained using the polarization potential determination method described in the above embodiments.

[0026] In the technical solution of this application embodiment, by fitting the current density change data corresponding to different polarization potentials, the positive polarization potential that enables the test battery pack to maintain a steady state under polarization is determined. Then, based on the test data obtained by performing electrochemical impedance spectroscopy and constant potential polarization tests on the test battery pack with the positive polarization potential, the positive ion migration number is determined, which can obtain a more accurate positive ion migration number.

[0027] In some embodiments, after determining the forward ion migration number of each test battery pack, the method further includes:

[0028] Obtain reverse polarization test data of the test battery pack. The reverse polarization test data includes test data obtained by performing reverse electrochemical impedance spectroscopy and reverse potentiostatic polarization tests on the test battery pack with reverse polarization potential.

[0029] Based on the reverse polarization test data, the reverse ion migration number of each test battery pack was determined;

[0030] The target ion migration number for each test battery pack is obtained based on the forward and reverse ion migration numbers.

[0031] The reverse polarization potential is obtained using the polarization potential determination method described in the above embodiments.

[0032] In the technical solution of this application embodiment, by performing reverse polarization testing on the test battery pack to determine the target ion migration number, the interface changes of the battery can be fully reflected, ensuring the consistency and accuracy of the test result data.

[0033] In some embodiments, the forward polarization test data includes forward voltage change data, first current change data, first electrochemical impedance spectroscopy data in the open circuit state, and second electrochemical impedance spectroscopy data in the polarized state.

[0034] Based on the forward polarization test data, the forward ion transference number of each test battery pack was determined to include:

[0035] The voltage in the forward voltage change data is corrected to obtain the forward polarization voltage;

[0036] Based on the forward polarization voltage, first current change data, first electrochemical impedance spectroscopy data, and second electrochemical impedance spectroscopy data, the forward ion migration number of each test battery pack was determined.

[0037] In the technical solution of this application embodiment, by correcting the polarization voltage, a more accurate and reasonable positive polarization voltage can be obtained, and further, the positive ion transference number measured based on the positive polarization voltage can be more accurate.

[0038] In some embodiments, the reverse polarization test data includes reverse voltage change data, second current change data, third electrochemical impedance spectroscopy data under polarized state and fourth electrochemical impedance spectroscopy data under open circuit state.

[0039] Based on the reverse polarization test data, the reverse ion transference number of each test battery pack was determined to include:

[0040] The voltage in the reverse voltage change data is corrected to obtain the reverse polarization voltage;

[0041] The reverse ion migration number of each test battery pack was determined based on the reverse polarization voltage, the second current change data, the third electrochemical impedance spectroscopy data, and the fourth electrochemical impedance spectroscopy data.

[0042] In the technical solution of this application embodiment, by correcting the polarization voltage, a more accurate and reasonable reverse polarization voltage can be obtained, and further, the reverse ion transference number measured based on the reverse polarization voltage can be more accurate.

[0043] In some embodiments, after obtaining the target ion mobility number for each test battery pack, the method further includes:

[0044] Obtain polarization verification data for the test battery pack, including data obtained from electrochemical impedance spectroscopy and potentiostatic polarization tests performed on the test battery pack using the reverse verification polarization potential.

[0045] Based on polarization verification data and reverse polarization test data, the ion migration number verification value for each test battery pack was determined;

[0046] By comparing the verified ion mobility number with the target ion mobility number, the target abnormal battery packs are selected based on the comparison results.

[0047] In the technical solution of this application embodiment, by performing verification tests on the test battery packs, it is possible to further verify whether there are any abnormalities in each test battery pack itself, whether there are any abnormalities in the test data and test result data, and to screen out abnormal battery packs so that testers can promptly investigate the abnormalities.

[0048] In some embodiments, the reverse polarization test data includes fourth electrochemical impedance spectroscopy data in the open-circuit state, and the polarization verification data includes reverse verification voltage change data, third current change data, and fifth electrochemical impedance spectroscopy data in the polarized state.

[0049] Based on polarization verification data and reverse polarization test data, the ion mobility number verification values ​​for each test battery pack were determined as follows:

[0050] The voltage in the reverse verification voltage change data is corrected to obtain the reverse verification polarization voltage;

[0051] Based on the reverse verification polarization voltage, the third current change data, the fourth electrochemical impedance spectroscopy data, and the fifth electrochemical impedance spectroscopy data, the verification value of the ion transport number for each test battery pack was determined.

[0052] In the technical solution of this application embodiment, by correcting the reverse verification polarization potential, a more accurate and true reverse verification polarization potential can be obtained, and based on the corrected reverse verification polarization potential, a more accurate ion transference number verification value can be obtained.

[0053] Thirdly, this application also provides an electrolyte ion transport number testing system. The system includes interconnected testing devices and testing control devices;

[0054] The test control device is used to perform ion mobility number testing of the test device using the electrolyte ion mobility number testing method described in the above embodiments, and to obtain the ion mobility number of the test device.

[0055] In some embodiments, the testing apparatus includes a button cell battery device.

[0056] In some embodiments, the coin cell device includes a separator and an insulating adhesive layer with through holes. The separator is embedded in the through holes. The difference between the inner diameter and the outer diameter of the insulating adhesive layer is a target value. The target value is used to make the detection area of ​​the coin cell device a separator without the insulating adhesive layer covering it.

[0057] In some embodiments, the test control device is further configured to perform electrochemical impedance spectroscopy testing on the test device at a test frequency not lower than the target cutoff frequency, the target cutoff frequency being used to maintain the steady state of the test device.

[0058] Fourthly, this application also provides a polarization potential determination device. The device includes:

[0059] The data acquisition module is used to acquire the current density change data obtained by constant potential polarization test of the test battery pack with different polarization potentials.

[0060] The data fitting module is used to fit the current density variation data to obtain the fitting parameters corresponding to different polarization potentials.

[0061] The target polarization potential determination module is used to determine the target polarization potential of the test battery pack based on the fitted parameters. The target polarization potential is used to maintain the steady state of the test battery pack.

[0062] Fifthly, this application also provides an electrolyte ion transport number testing device. The device includes:

[0063] The test data acquisition module is used to acquire the forward polarization test data of the test battery pack. The forward polarization test data includes test data obtained by performing electrochemical impedance spectroscopy and constant potential polarization tests on the test battery pack with forward polarization potential.

[0064] The forward ion migration number determination module is used to determine the forward ion migration number of each test battery pack based on the forward polarization test data.

[0065] The positive polarization potential is obtained using the polarization potential determination method described in the above embodiments.

[0066] Sixthly, this application also provides a computer device. The computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the steps in the above-described polarization potential determination method or the above-described electrolyte ion transport number testing method.

[0067] Seventhly, this application also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program thereon, which, when executed by a processor, implements the steps in the above-described polarization potential determination method or the above-described electrolyte ion transport number testing method.

[0068] Eighthly, this application also provides a computer program product. The computer program product includes a computer program that, when executed by a processor, implements the steps in the above-described polarization potential determination method or the above-described electrolyte ion transport number testing method.

[0069] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0070] Figure 1 This is a diagram illustrating the application environment of the polarization potential determination method or the electrolyte ion transport number testing method in some embodiments of this application;

[0071] Figure 2 This is a flowchart illustrating the polarization potential determination method in some embodiments of this application;

[0072] Figure 3 This is a flowchart illustrating the polarization potential determination method in some other embodiments of this application;

[0073] Figure 4 This is a detailed flowchart illustrating the polarization potential determination method in some embodiments of this application;

[0074] Figure 5 To obtain j~ in some embodiments of this application, the polarization potential at 10mV (millivolts) was fitted. Schematic diagram of the curve;

[0075] Figure 6 To obtain j~ in some embodiments of this application, the polarization potential at 15mV was fitted. Schematic diagram of the curve;

[0076] Figure 7 To obtain j~ in some embodiments of this application, the polarization potential of 20mV was fitted. Schematic diagram of the curve;

[0077] Figure 8 This is a flowchart illustrating the electrolyte ion transport number testing method in some embodiments of this application;

[0078] Figure 9 This is a flowchart illustrating the electrolyte ion transport number testing method in some other embodiments of this application;

[0079] Figure 10 This is a flowchart illustrating the electrolyte ion transport number testing method in some embodiments of this application;

[0080] Figure 11 This is a detailed flowchart illustrating the electrolyte ion transport number testing method in some embodiments of this application;

[0081] Figure 12 This is a schematic diagram of the electrolyte ion transport number testing system in some embodiments of this application;

[0082] Figure 13 This is a partial structural schematic diagram of the button battery device in some embodiments of this application;

[0083] Figure 14 This is a structural block diagram of the polarization potential determination device in some embodiments of this application;

[0084] Figure 15 This is a structural block diagram of the electrolyte ion transport number testing device in some embodiments of this application;

[0085] Figure 16 This is a structural block diagram of the electrolyte ion transport number testing device in some other embodiments of this application;

[0086] Figure 17 This is a diagram showing the internal structure of a computer device in some embodiments of this application. Detailed Implementation

[0087] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0088] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0089] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0090] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least some embodiments of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0091] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0092] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0093] Ion transport number is a parameter used to evaluate the ability of ions to migrate. The electrolyte, as a crucial component of a battery, plays a role in ion transport between the positive and negative electrodes. For electrolytes, whether liquid or solid, transport number is an important parameter for evaluating their ion transport capabilities.

[0094] Taking lithium-ion transference number as an example, it is usually defined as the proportion of the number of migrating ions to the total number of migrating ions in the electrolyte. The operation of a lithium-ion battery involves the insertion and extraction of lithium ions at the positive and negative electrodes. During the charging and discharging process of a lithium-ion battery, cations and anions migrate between the positive and negative electrodes, where Li... + Positively charged molecules will migrate towards the negative electrode under the influence of an electric field; Li in the electrolyte... + The migration coefficient is closely related to the insertion and extraction of lithium ions on both the positive and negative electrode sides. The performance of lithium-ion batteries can be predicted by testing the lithium-ion migration number in the electrolyte. A high migration coefficient is of great significance for improving the power density and energy density of lithium-ion batteries.

[0095] Currently, the method of testing ion transport numbers using the constant potential polarization method suffers from low accuracy. To ensure the steady state of the battery, the polarization potential used is often a fixed value commonly used in the industry, such as 10mV. However, a fixed polarization potential is not universally applicable. The most suitable polarization potential varies depending on the electrolyte's conductivity. For example, a polarization potential of 10mV is not suitable for electrolytes with high conductivity. The viscosity of high-conductivity electrolytes decreases, and convection and diffusion are enhanced, which is insufficient to maintain the battery's steady state at that polarization potential. Thus, the final measured electrolyte ion transport number will be inaccurate.

[0096] Taking lithium-ion transference number testing as an example, referring to the diffusion current formula for the limiting diffusion control of a planar electrode (lithium-ion deposited lithium sheet) when the product is insoluble, we have: According to Fick's second law Three boundary conditions can be set:

[0097] Condition 1: Initially, the liquid phase concentration is the initial concentration, i.e. , ;

[0098] Condition 2: At any given time, the concentration of the liquid phase sufficiently far from the solid-liquid boundary is the initial concentration, i.e. ;

[0099] Condition 3: When the limiting diffusion is controlled and the product is insoluble (graphite), the solid-liquid interface at any given time is the liquid concentration at the surface, i.e. .

[0100] Based on the above three boundary conditions, the concentration gradient under the limiting diffusion control can be calculated: Substituting this into the diffusion current formula, we get: .

[0101] In the formula, D is the diffusion coefficient (m² / s), and C is the volume concentration of the diffusing substance (component). denoted as , where is the distance from the solid-liquid boundary, and j is the current density.

[0102] As can be seen from the above, the current density has a functional relationship with time, i.e., j~ The relationship appears linear, but actual testing revealed that at a polarization potential of 10mV, the test results for the highly conductive electrolyte showed a different trend. The relationship is not linear, indicating that a polarization potential of 10 mV is not suitable for transport number testing of highly conductive electrolytes.

[0103] Based on the above findings, this application proposes a method for determining polarization potential, taking into account the linear relationship between current density and time. Specifically, it acquires current density variation data obtained by performing constant potential polarization tests on a test battery pack at different polarization potentials. Then, it performs fitting processing on the current density variation data to obtain fitting parameters corresponding to different polarization potentials. Finally, based on the fitting parameters, it determines the target polarization potential of the test battery pack, which is used to maintain the test battery pack in a steady state under polarization. This process differs from the traditional approach of using a universal fixed value for constant potential polarization testing. By fitting the current density variation data corresponding to different polarization potentials, it determines the target polarization potential that enables the test battery pack to maintain a steady state under polarization. This allows for the targeted determination of the optimal polarization potential for the test battery pack and supports constant potential polarization testing using this target polarization potential, resulting in more accurate measured ion transference numbers.

[0104] The polarization potential method provided in this application embodiment can be applied to, for example... Figure 1In the application environment shown, the test battery pack 102 is interconnected with the test control device 104. The test control device 104 acquires current density change data obtained by performing constant potential polarization tests on the test battery pack 102 with different polarization potentials. Then, it performs fitting processing on the current density change data to obtain fitting parameters corresponding to different polarization potentials. Based on the fitting parameters, it determines the target polarization potential of the test battery pack 102, which is used to maintain the test battery pack in a steady state under polarization. The test battery pack 102 includes multiple battery packs, and the batteries can be general-purpose batteries, such as lithium batteries. The current density change data can be obtained by the test control device 104 directly testing the test battery pack 102, or it can be obtained by testing the test battery pack 102 with other testing instruments, depending on the actual situation, and is not limited here. The test control device 104 is a device with data processing capabilities.

[0105] In some embodiments, such as Figure 2 As shown, a method for determining polarization potential is provided, which can be applied to... Figure 1 The following steps are used as an example of the test control device 104:

[0106] Step S202: Obtain the current density change data obtained by performing constant potential polarization test on the test battery pack with different polarization potentials.

[0107] Polarization potential refers to the potential (i.e., voltage) used when performing constant potential polarization tests on the test battery pack. Current density variation data refers to the change in current density over time, including the current density at different time points. In this embodiment, the current density is the ratio of the actual measured current value to the electrode area, i.e. The unit is Where j is the current density, I is the current value, and S is the electrode area. The test battery pack can consist of multiple batteries, and can also be a symmetrical battery system. The symmetrical battery system in the test battery pack can be a general-purpose battery, such as a reusable battery, or a disposable battery, such as a button cell.

[0108] In practice, the test procedure for the test control device to perform constant potential polarization testing (hereinafter referred to as CA testing) on ​​the battery pack under test with different polarization potentials can be as follows:

[0109] ① Let it stand for 10 seconds;

[0110] ②CA test: Test parameters include: polarization potential 5 mV vs. Eoc, test duration 10 minutes. The polarization time can be modified from 5 to 20 minutes. The initial value of the polarization potential can be 5 to 10 mV or other values.

[0111] ③ Let it stand for 20 minutes. The standing time can vary from 10 to 30 minutes, as long as the test battery pack can return to a steady state.

[0112] ④CA test: The test parameters include polarization potential 7 mV vs. Eoc, and the test duration is 10 minutes. The gradient of the polarization potential can be varied, and the gradient can be 1 mV, 2 mV or up to 5 mV. In this embodiment, 2 mV is selected. The smaller the gradient, the more accurate the final result.

[0113] Repeat steps ③ and ④, increasing the polarization potential according to the gradient until the polarization potential reaches the upper limit of the polarization potential, such as 20mV. In other embodiments, the final upper limit of the polarization potential can also be a value between 20 and 30mV or other values.

[0114] The current density data obtained during constant potential polarization testing of the test battery pack with different polarization potentials are collected, thus obtaining the current density change data corresponding to different polarization potentials.

[0115] Step S204: Fit the current density change data to obtain the fitting parameters corresponding to different polarization potentials.

[0116] After obtaining the above current density variation data, the current density variation data under different polarization potentials can be arranged according to the horizontal axis. The vertical axis represents the current density. This method involves fitting the current density variation data to observe whether the current density is a function of time. Specifically, curve fitting or polynomial fitting can be performed on the current density variation data to obtain fitting parameters corresponding to different polarization potentials.

[0117] Step S206: Determine the target polarization potential of the test battery pack based on the fitting parameters. The target polarization potential is used to maintain the test battery pack in a steady state under polarization.

[0118] The target polarization potential refers to the optimal polarization potential that enables the test battery pack to maintain a steady state in the polarized state. From another perspective, the target polarization potential can be regarded as the polarization potential that best matches the current density with the decay law of diffusion current.

[0119] Following the above embodiments, after obtaining the fitting parameters, the fitting parameters can be compared with preset fitting coefficients to determine whether the battery maintains a steady state under each polarization potential, and whether the change in current density follows the diffusion current decay law. In this way, the target polarization potential that best matches the current density with the diffusion current decay law can be determined.

[0120] In the technical solution of this application embodiment, the current density change data obtained by performing constant potential polarization tests on the test battery pack with different polarization potentials are fitted to obtain fitting parameters corresponding to different polarization potentials. Then, based on the fitting parameters, the target polarization potential that enables the test battery pack to maintain a steady state under polarization is determined. This process differs from the traditional method of using a universal fixed value for constant potential polarization testing. By fitting the current density change data corresponding to different polarization potentials, the target polarization potential that enables the test battery pack to maintain a steady state under polarization can be determined specifically. This allows for the targeted determination of the optimal polarization potential for the test battery pack and supports constant potential polarization testing using this target polarization potential, resulting in more accurate measured ion transference numbers.

[0121] like Figure 3 As shown, in some embodiments, step S204 includes: step S224, performing curve fitting processing on the current density change data to obtain fitting parameters.

[0122] In practical applications, multiple tests have shown that the current density should have a functional relationship with time, i.e., j~ Since the relationship is functional, in this embodiment, curve fitting can be performed on the current density change data to characterize the functional relationship between current density and time, such as j~ The curve is derived from the corresponding fitting parameters.

[0123] In the technical solution of this application embodiment, by performing curve fitting on the current density change data, the relationship between current density and time can be characterized simply and quickly, which facilitates the selection of target polarization potential.

[0124] like Figure 4 As shown, in some embodiments, step S224 includes: step S244, selecting target current density change data within a preset time range from the current density change data, performing linear regression fitting on the target current density change data, and obtaining linear regression fitting parameters.

[0125] Linear regression fitting, often simply called linear fitting, is a type of curve fitting. The parameters for linear regression fitting include the slope. The correlation coefficient between the value and the fit Value. In practical applications, preliminary experimental test data shows that abnormal changes in current density usually occur in... The range is 0 to 1, that is, within When the value is between 0 and 1, the current density does not conform to the diffusion current decay law. Therefore, in this embodiment, the horizontal axis can be selected. For the current density variation data ranging from 0 to 1, the least squares method is used to perform linear fitting on the current density variation data to obtain the slope of the fitting formula. The correlation coefficient between the value and the fit Value. It is understood that in other embodiments, current density variation data within other ranges can be selected, and other linear fitting algorithms such as gradient descent can be used to fit the current density variation data.

[0126] In the technical solution of this application embodiment, by performing linear regression fitting on the current density change data within a preset time range, the linear regression fitting parameters can be obtained quickly and accurately.

[0127] like Figure 3 As shown, in some embodiments, step S206 includes: step S226, comparing the linear regression fitting parameters with preset linear coefficients, and determining the target polarization potential of the test battery pack based on the comparison results and preset polarization potential selection rules.

[0128] In this embodiment, the linear coefficient is . The closer the linear coefficient is to 1, the stronger the linear relationship, and the closer the polarization potential is to the optimal polarization potential. However, since the fitted linear coefficients are not integers of 1 in most cases, in this embodiment, the preset linear coefficients are... It can be 0.85. The preset polarization potential selection rules can include: (1) j~ The curve is There should be no abnormal inflection point, and the relationship should conform to linearity; (2) j~ The curve is When the current approaches zero, no abnormal rebound occurs.

[0129] In practice, the linear regression fitting parameters corresponding to each polarization potential obtained by fitting can be used. Compared with the preset linear coefficients, if the linear regression fitting parameters... When j~ is reached, it is determined that j~ is the polarization potential under that polarization potential. If a linear relationship is found, this can be used as the polarization potential for ion transport number testing. Then, the polarization potential corresponding to the linear regression fitting parameter closest to 1 is selected. Simultaneously, considering the polarization potential selection rules, if the fitted j~ The curve is No abnormal inflection point appeared at that time, and in If no abnormal current rebound occurs when the current approaches 0, the polarization potential corresponding to the linear regression fitting parameter closest to 1 is determined as the target polarization potential.

[0130] In the technical solution of this application embodiment, the target polarization potential of the test battery pack is determined by a preset linear coefficient and a preset polarization potential selection rule, which makes the determined target polarization potential more accurate and objective.

[0131] To provide a clearer explanation of the polarization potential determination method provided in the embodiments of this application, the following description is in conjunction with the accompanying drawings. Figure 4 The following specific embodiments will be described:

[0132] Step S202: Obtain the current density change data obtained by performing constant potential polarization test on the test battery pack with different polarization potentials.

[0133] In this embodiment, test data can be obtained by performing constant polarization tests on a test battery pack containing a highly conductive electrolyte at polarization potentials of 10mV, 15mV, and 20mV.

[0134] Step S244: Select target current density change data within a preset time range from the current density change data, perform linear regression fitting on the target current density change data, and obtain the linear regression fitting parameters.

[0135] Then, the current density variation data under different polarization potentials were arranged according to the x-axis. The vertical axis represents the current density. Process it in this way, selecting the x-axis. For the target current density variation data ranging from 0 to 1, the least squares method is used to perform linear fitting on the target current density variation data to obtain the slope of the fitting formula. The correlation coefficient between the value and the fit Values. Specifically, the j~ values ​​corresponding to the fitted polarization potentials of 10mV, 15mV, and 20mV. The curves are respectively as follows Figure 5 , Figure 6 and Figure 7 As shown.

[0136] Step S226: Compare the linear regression fitting parameters with the preset linear coefficients, and determine the target polarization potential of the test battery pack based on the comparison results and the preset polarization potential selection rules.

[0137] In practice, the linear regression fitting parameters corresponding to each polarization potential will be used. Compared with the preset linear coefficients, if the linear regression fitting parameters... When j~ is reached, it is determined that j~ is the polarization potential under that polarization potential. If a linear relationship is found, this can be used as the polarization potential for ion transport number testing. Then, the polarization potential corresponding to the linear regression fitting parameter closest to 1 is selected. Simultaneously, considering the polarization potential selection rules, if the fitted j~ The curve is No abnormal inflection point appeared at that time, and in If no abnormal current rebound occurs when the current approaches 0, the polarization potential corresponding to the linear regression fitting parameter closest to 1 is determined as the target polarization potential.

[0138] In this embodiment, j~ corresponds to polarization potentials of 10mV, 15mV, and 20mV. The curve, and the final determined linear regression fitting parameters. The values ​​are shown in Table 1:

[0139] Table 1. Linear regression fitting parameters for the three polarization potentials value

[0140] 10mV 15mV 20mV Parallel Sample 1 0.546 0.442 1.066 Parallel Sample 2 0.198 0.406 0.385 Parallel Sample 3 0.083 0.449 0.483 Parallel Sample 4 0.102 0.447 0.433

[0141] As can be seen from the table above, the target polarization potential of the test battery pack containing highly conductive electrolyte should be 20mV.

[0142] Based on the same inventive concept, this application also provides a method for testing the ion transport number of an electrolyte. This method for testing the ion transport number of an electrolyte can also be applied to, for example... Figure 1 In the application environment shown, the test battery pack 102 is interconnected with the test control device 104. The test control device 104 acquires the forward polarization test data of the test battery pack 102. The forward polarization test data includes test data obtained by performing electrochemical impedance spectroscopy and potentiostatic polarization tests on the test battery pack 102 with a forward polarization potential. Based on the forward polarization test data, the forward ion migration number of each test battery pack is determined. The forward polarization potential is obtained using the polarization potential determination method described in the above embodiment. The test battery pack 102 includes multiple battery packs, and the batteries can be general-purpose batteries, such as lithium batteries. The current density change data can be obtained by the test control device 104 directly testing the test battery pack 102, or it can be obtained by testing the test battery pack 102 with other testing instruments, depending on the actual situation, and is not limited here. The test control device 104 is a device with data processing capabilities.

[0143] In some embodiments, such as Figure 8 As shown, a method for determining polarization potential is provided, which can be applied to... Figure 1 The following steps are used as an example of the test control device 104:

[0144] Step S402: Obtain the forward polarization test data of the test battery pack. The forward polarization test data includes test data obtained by performing electrochemical impedance spectroscopy and constant potential polarization tests on the test battery pack with the forward polarization potential. The forward polarization potential is obtained by the polarization potential determination method described in the above embodiment.

[0145] Forward polarization potential refers to forward voltage, such as mV. In this embodiment, the number of test battery packs can be multiple, and they can also be symmetrical battery systems. The symmetrical battery system in the test battery pack can be a general-purpose battery, such as a reusable battery, or a disposable battery, such as a coin cell. In this embodiment, taking the lithium-ion transference number test as an example, the test battery pack can be a lithium battery pack. Forward polarization test data refers to the test data obtained by performing electrochemical impedance spectroscopy and potentiostatic polarization tests on the test battery pack with a forward voltage. The test data includes voltage-time data, current-time data, and electrochemical impedance spectroscopy data before and after polarization, etc.

[0146] It is understood that, in this embodiment, before acquiring the forward polarization test data, the test control device further includes determining the forward polarization potential for electrochemical impedance spectroscopy and constant potential polarization testing using the polarization potential determination method described in the above embodiment. After determining the forward polarization potential, the test battery pack is subjected to electrochemical impedance spectroscopy and constant potential polarization testing according to the corresponding forward polarization potential to obtain forward polarization test data. Alternatively, a test command carrying the forward polarization potential is sent to an external test instrument connected to the test battery pack, so that the test instrument performs electrochemical impedance spectroscopy and constant potential polarization testing on the test battery pack with the forward polarization potential, and receives the forward polarization test data sent by the external test instrument.

[0147] Step S404: Determine the forward ion migration number of each test battery pack based on the forward polarization test data.

[0148] In this embodiment, after obtaining the aforementioned forward polarization test data, the forward ion migration value of each test battery pack can be determined based on the ion mobility number test principle, according to voltage data, current data, and electrochemical impedance spectroscopy data. .

[0149] Taking the testing of lithium-ion transference number as an example, the lithium-ion transference number can be determined in the following way:

[0150] Extracting the initial current from the current data With steady-state current If the effect of interface impedance on the testing process is not considered, then the lithium-ion mobility number... for:

[0151] (1)

[0152] If we consider the influence of interface impedance on the testing process, then we have:

[0153] (2)

[0154] (3)

[0155] In the formula, The first interface impedance before polarization. The second interface impedance after polarization. Polarization voltage, This is the electrolytic cell constant (length / surface area). The conductivity of the electrolyte.

[0156] In this embodiment, taking the influence of interface impedance on the testing process as an example, by combining formulas (1), (2), and (3), the formula for calculating the lithium-ion transference number can be obtained as follows:

[0157] (4)

[0158] In specific implementation, the electrochemical impedance spectroscopy data before and after polarization can be subjected to impedance fitting to obtain the corresponding battery impedance data, including the interfacial impedance, ohmic impedance and charge transfer impedance before and after polarization. Then, the polarization voltage in the voltage change data and the initial current and steady-state current in the current change data are extracted. Taking the test battery pack as a unit, for each test battery pack, its corresponding polarization voltage, initial current, steady-state current, interfacial impedance before polarization and interfacial impedance after polarization are substituted into formula (4) to obtain the lithium-ion transference number of each test battery pack.

[0159] In some other embodiments, if the influence of interface impedance and ohmic impedance on the test process is considered simultaneously, then the above formulas (2) and (3) need to be adjusted. The adjusted formulas are as follows:

[0160] (5)

[0161] (6)

[0162] In the formula, The first ohmic impedance measured in the EIS test before polarization. This is the second ohmic impedance measured in the EIS test after polarization.

[0163] Combining formulas (1), (5), and (6), we have:

[0164] (7)

[0165] In specific implementation, the electrochemical impedance spectra before and after polarization can be subjected to impedance fitting processing to extract the first interface impedance and the first ohmic impedance before polarization, as well as the second interface impedance and the second ohmic impedance after polarization. The corresponding polarization voltage, initial current, steady-state current, first interface impedance, first ohmic impedance, second interface impedance and second ohmic impedance are substituted into formula (7) to obtain the ion migration number of each test battery pack.

[0166] In some embodiments, in addition to considering the influence of interface impedance and ohmic impedance on the test process, the influence of diaphragm impedance on the test process is also considered. That is, the above formula (7) needs to be adjusted. The adjusted formula is as follows:

[0167] (8)

[0168] In the formula, z is a correction coefficient used to correct for ohmic impedance. In this embodiment, .

[0169] In practice, each battery pack being tested can be used as an example unit. The first ohmic impedance and the second ohmic impedance can be corrected according to a preset correction factor to obtain the first target ohmic impedance. Second target ohmic impedance Then, the target polarization voltage, initial current, steady-state current, first interface impedance, first target ohmic impedance, second interface impedance and second target ohmic impedance are substituted into formula (8) to obtain the forward ion migration number of each test battery pack.

[0170] In the technical solution of this application embodiment, by fitting the current density change data corresponding to different polarization potentials, the positive polarization potential that enables the test battery pack to maintain a steady state under polarization is determined. Then, based on the test data obtained by performing electrochemical impedance spectroscopy and constant potential polarization tests on the test battery pack with the positive polarization potential, the positive ion migration number is determined, which can obtain a more accurate positive ion migration number.

[0171] like Figure 9 As shown, in some embodiments, after step S404, the method further includes:

[0172] Step S406: Obtain reverse polarization test data of the test battery pack. The reverse polarization test data includes test data obtained by performing reverse electrochemical impedance spectroscopy and reverse potentiostatic polarization tests on the test battery pack with reverse polarization potential. The reverse polarization potential is obtained by the polarization potential determination method described in the above embodiments.

[0173] Step S408: Determine the reverse ion migration number of each test battery pack based on the reverse polarization test data.

[0174] Step S410: Based on the forward ion migration number and the reverse ion migration number, the target ion migration number of each test battery pack is obtained.

[0175] In practical applications, the test process only applies a unidirectional polarization potential (the electrode in the direction of lithium ion migration when a positive polarization potential is applied is defined as the working electrode, and the other electrode is defined as the counter electrode). During the unidirectional polarization test, lithium deposition occurs at the solid-liquid interface of the working electrode, which changes the interface state to some extent, while this process does not occur at the solid-liquid interface of the counter electrode. The interface impedance measured at this time cannot fully reflect the interface changes of the symmetrical battery. Therefore, in this embodiment, a reverse polarization test is added to improve the process.

[0176] In this embodiment, the reverse polarization potential refers to the reverse voltage, such as... In this embodiment, similarly, the reverse polarization potential is obtained by the test control device according to the polarization potential determination method described in the above embodiment. The reverse polarization test data includes test data obtained by performing reverse electrochemical impedance spectroscopy and reverse potentiostatic polarization tests on the test battery pack at a reverse polarization potential of -20mV. The test data includes voltage-time data, current-time data, and electrochemical impedance spectroscopy data under various conditions.

[0177] The reverse ion migration number of each test battery pack can be determined by referring to the method for determining the forward ion migration number, such as formulas (4), (7), or (8). .

[0178] The reverse polarization test is to ensure that the working electrode and the counter electrode of the test battery pack are in the same state. Therefore, the reverse ion transference number is calculated by the reverse test. It should be related to the positive ion transference number The differences are not significant, but they are not entirely the same. Therefore, in this embodiment, after obtaining the reverse ion transference number... It can be made ,like (This value is an empirical value and can be taken between 0.05 and 0.2 depending on the situation.) If this value is found to be abnormal, the reverse ion migration value of the test battery pack is considered to be abnormal. It should be related to the positive ion migration value Data from these parallel samples lack accuracy and should be discarded. Then determine the reverse ion mobility number of the test battery pack. It should be related to the positive ion transference number Normally, ultimately, the target ion migration value t for the test battery pack was determined to be the reverse ion migration value. It should be related to the positive ion migration value The average value, i.e. In other embodiments, the target ion mobility number t can also be used, or other methods can be employed, such as using the reverse ion mobility number. It should be related to the positive ion transference number The value is obtained by adding or subtracting the preset error value from the average value. The specific value can be determined according to the actual situation and is not limited here.

[0179] In the technical solution of this application embodiment, by performing reverse polarization testing on the test battery pack to determine the target ion migration number, the interface changes of the battery can be fully reflected, ensuring the consistency and accuracy of the test result data.

[0180] like Figure 10 As shown, in some embodiments, the forward polarization test data includes forward voltage change data, first current change data, first electrochemical impedance spectroscopy data in the open-circuit state, and second electrochemical impedance spectroscopy data in the polarized state.

[0181] Step S404 includes: Step S424, correcting the voltage in the forward voltage change data to obtain the forward polarization voltage, and determining the forward ion migration number of each test battery pack based on the forward polarization voltage, the first current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data.

[0182] In this embodiment, the forward polarization test data includes forward voltage change data, first current change data, first electrochemical impedance spectroscopy data under open-circuit conditions, and second electrochemical impedance spectroscopy data under polarized conditions. In practical applications, the forward voltage change data includes the open-circuit voltage, which can be positive or negative. The forward polarization voltage refers to the true polarization voltage of each test battery pack during the corrected test process. Currently, in ion mobility number testing, a polarization voltage of 10 mV is generally selected to keep the test battery in a steady state as much as possible during the test. In the subsequent ion mobility number calculation, the 10 mV voltage value is generally directly substituted into the corresponding calculation formula to obtain the ion mobility number. However, in actual testing, due to the influence of the electrochemical workstation channel or the assembled battery system, the open-circuit voltage of the test battery is often not 0 mV, and the applied true voltage is often not equal to 10 mV. Moreover, the true voltage value is closely related to the test battery. If the ion mobility number is directly calculated from the applied polarization voltage, it will lead to a deviation between the final measured ion mobility number and the true value. Therefore, in this embodiment, the polarization voltage of each group of test batteries can be individually corrected to obtain the true target polarization voltage.

[0183] In actual testing, the open-circuit voltage of the test battery pack may be negative. Therefore, in this embodiment, the polarization voltage is corrected based on the voltage change data to obtain the target polarization voltage. This can be done by calculating the average voltage value based on each voltage value in the voltage change data, and then obtaining the target polarization voltage based on the average voltage value and the open-circuit voltage value.

[0184] Specifically, record the open-circuit voltage value of the test battery pack under open-circuit conditions. The average value of the voltage recorded during the test is recorded as . The actual forward polarization voltage is :

[0185] (9)

[0186] After obtaining the positive polarization voltage, impedance fitting can be performed on the first and second electrochemical impedance spectroscopy (EIS) data using a fitting tool to obtain the first and second cell impedance data. These data can be represented as first and second EIS curves. The first EIS curve includes data such as the second interface impedance after polarization, the first ohmic impedance, and the charge transfer impedance. The second EIS data includes data such as the first interface impedance, the second ohmic impedance, and the charge transfer impedance before polarization.

[0187] In practice, this can be done on a per-test-battery-pack basis, extracting the initial current from the first current change data for each test-battery-pack. and steady-state current The true forward polarization voltage can be obtained using formula (9). Then, the first electrochemical impedance spectroscopy data is fitted to obtain the first interfacial impedance before polarization. The second interfacial impedance after polarization was obtained by fitting the second electrochemical impedance spectroscopy data. Substituting the above parameters into formulas (4), (7), or (8), the ion migration values ​​for the forward polarization test of each test battery pack can be obtained. .

[0188] In the technical solution of this application embodiment, by correcting the polarization voltage, a more accurate and reasonable positive polarization voltage can be obtained, and further, the positive ion transference number measured based on the positive polarization voltage can be more accurate.

[0189] In some embodiments, such as Figure 10 As shown, step S408 includes:

[0190] Step S428: Correct the voltage in the reverse voltage change data to obtain the reverse polarization voltage. Based on the reverse polarization voltage, the second current change data, the third electrochemical impedance spectroscopy data, and the fourth electrochemical impedance spectroscopy data, determine the reverse ion migration number of each test battery pack.

[0191] The reverse polarization test data includes reverse voltage change data, second current change data, third electrochemical impedance spectroscopy data under polarization state, and fourth electrochemical impedance spectroscopy data under open circuit state. In this embodiment, the open circuit voltage value of the test battery pack under open circuit state is recorded during the reverse test. The average value of the voltage recorded during the test is recorded as . The actual reverse polarization voltage is :

[0192] (10)

[0193] After obtaining the reverse polarization voltage, impedance fitting can be performed on the third electrochemical impedance spectroscopy data using a fitting tool to obtain the third cell impedance data, which can be represented as a third electrochemical impedance spectroscopy curve. This curve includes data such as the third interface impedance before polarization, the third ohmic impedance, and the charge transfer impedance.

[0194] In practice, this can be done on a per-test-battery-pack basis, extracting the initial current from the second current change data for each test-battery-pack. and steady-state current The true reverse polarization voltage can be obtained using formula (10). Then, the third electrochemical impedance spectroscopy data is fitted to obtain the third interfacial impedance before polarization. The fourth interfacial impedance after polarization was obtained by fitting the fourth electrochemical impedance spectroscopy data. Substituting the above parameters into formulas (4), (7), or (8), the reverse ion migration values ​​for the reverse polarization test of each test battery pack can be obtained. .

[0195] In the technical solution of this application embodiment, by correcting the polarization voltage, a more accurate and reasonable reverse polarization voltage can be obtained, and further, the reverse ion transference number measured based on the reverse polarization voltage can be more accurate.

[0196] like Figure 10 As shown, in some embodiments, after step S410, the method further includes:

[0197] Step S412: Obtain polarization verification data of the test battery packs. Based on the polarization verification data and reverse polarization test data, determine the ion migration number verification value of each test battery pack. Compare the ion migration number verification value with the target ion migration number. Based on the comparison results, select the target abnormal battery packs.

[0198] Polarization verification data includes reverse verification of polarization potential (e.g., - The test data obtained from electrochemical impedance spectroscopy and potentiostatic polarization tests on the test battery packs are as follows: similarly, polarization verification data may include current change data, voltage change data, and electrochemical impedance spectroscopy data under polarization states. In this embodiment, after obtaining the polarization verification data, each test battery pack can be used as a unit. Based on the polarization verification data and reverse polarization test data, combined with the ion mobility number test principle, the corresponding data can be substituted into formulas (4), (7), or (8) to obtain the ion mobility number verification value of each test battery pack. Then, compare the ion mobility number verification values. and target ion mobility number verification value ,make ,like If the battery assembly and test data and results for that group are deemed normal, then it is determined that there are no abnormalities. If any abnormality is found in the battery assembly, test data, and test results of that test group, the battery group is marked as an abnormal battery group. Following this method, each battery group under test is compared to select the correct test battery group. Furthermore, an anomaly handling message can be sent so that testers can promptly identify and correct the problem. It is understood that the error threshold of 0.05 is an empirical value. In other embodiments, the error threshold can also be a value between 0.02 and 0.1, or other values, depending on the actual situation, and is not limited here.

[0199] In the technical solution of this application embodiment, by performing verification tests on the test battery packs, it is possible to further verify whether there are any abnormalities in each test battery pack itself, whether there are any abnormalities in the test data and test result data, and to screen out abnormal battery packs so that testers can promptly investigate the abnormalities.

[0200] In some embodiments, determining the ion mobility number verification value of each test battery pack based on polarization verification data and reverse polarization test data includes: correcting the voltage in the reverse verification voltage change data to obtain the reverse verification polarization voltage, and determining the ion mobility number verification value of each test battery pack based on the reverse verification polarization voltage, the third current change data, the fourth electrochemical impedance spectroscopy data, and the fifth electrochemical impedance spectroscopy data.

[0201] Following the above embodiments, the reverse polarization test data includes fourth electrochemical impedance spectroscopy data in the open-circuit state, and the polarization verification data includes reverse verification voltage change data, third current change data, and fifth electrochemical impedance spectroscopy data in the polarization state. In specific implementation, for each test battery pack, the initial current can be extracted from the third current change data. and steady-state current The true reverse polarization voltage can be obtained using formula (10). The fourth interfacial impedance before polarization was obtained by fitting the fourth electrochemical impedance spectroscopy data. The interfacial impedance before polarization in this calculation Establish relationships: The fifth electrochemical impedance spectroscopy data were fitted to obtain the polarized fifth interfacial resistance. Substituting the above parameters into formulas (4), (7), or (8), the ion mobility number verification value for each test battery pack can be obtained. .

[0202] In the technical solution of this application embodiment, by correcting the reverse verification polarization potential, a more accurate and true reverse verification polarization potential can be obtained, and based on the corrected reverse verification polarization potential, a more accurate ion transference number verification value can be obtained.

[0203] To provide a clearer explanation of the ion mobility number testing method provided in this application, the following is in conjunction with the appendix. Figure 11 and one A specific embodiment will be described below:

[0204] Specifically, the ion mobility number test procedure can be as follows:

[0205] Part 1: Forward polarization test, obtaining forward polarization test data.

[0206] Let it stand for 10 seconds (the standing time can be changed and is not fixed);

[0207] EIS test: polarization potential 0mV vs. Eoc, test frequency 300MHz~1Hz; (interface impedance test before polarization).

[0208] Let stand for 30 minutes;

[0209] CA Test: Polarization Potential mV vs. Eoc, test duration 10 minutes; (mV is the determined optimal target polarization potential)

[0210] EIS test: Polarization potential mV vs. Eoc, test frequency 300MHz~1Hz; (interface impedance test after polarization) (To determine the optimal target polarization potential)

[0211] Part Two: Reverse Polarization Test, Obtaining Reverse Polarization Test Data

[0212] Let stand for 30 minutes (the standing time can be changed to restore steady state; 10 to 60 minutes is acceptable).

[0213] EIS test: polarization potential 0mV vs. Eoc, test frequency 300MHz~1Hz (interface impedance test before polarization).

[0214] Let stand for 30 minutes;

[0215] CA Test: Polarization Potential mV vs. Eoc, test duration 10 minutes ( mV is the determined optimal target polarization potential).

[0216] EIS test: Polarization potential mV vs. Eoc, test frequency 300MHz~1Hz (reverse polarization test, interface impedance test after polarization) (to determine the optimal target polarization potential).

[0217] Part 3: Cross-repeatability validation test, obtaining inverse polarization validation data.

[0218] Let it stand for 30 minutes (10-60 minutes is acceptable).

[0219] CA Test: vs. Eoc, test duration 10min (x ranges from -3 to 3mV and ≠ 0).

[0220] EIS test: vs. Eoc, test frequency 300MHz~1Hz.

[0221] Through the above testing process, forward polarization test data, reverse polarization test data, and reverse polarization verification data can be obtained respectively. This specific embodiment includes the following steps:

[0222] Step S422: Obtain forward polarization test data of the test battery pack. The forward polarization test data includes forward voltage change data, first current change data, first electrochemical impedance spectroscopy data under open circuit state, and second electrochemical impedance spectroscopy data under polarization state.

[0223] Step S424: Correct the voltage in the forward voltage change data to obtain the forward polarization voltage. Based on the forward polarization voltage, the first current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data, determine the forward ion migration number of each test battery pack.

[0224] In practice, this can be done on a per-test-battery-pack basis, extracting the initial current from the first current change data for each test-battery-pack. and steady-state current The true forward polarization voltage can be obtained using formula (9). Then, the first electrochemical impedance spectroscopy data is fitted to obtain the first interfacial impedance before polarization. The second interfacial impedance after polarization was obtained by fitting the second electrochemical impedance spectroscopy data. Substituting the above parameters into formulas (4), (7), or (8), the ion migration values ​​for the forward polarization test of each test battery pack can be obtained. .

[0225] Step S426: Obtain reverse polarization test data of the test battery pack. The reverse polarization test data includes reverse polarization voltage, second current change data, third electrochemical impedance spectroscopy data in the open circuit state, and fourth electrochemical impedance spectroscopy data in the polarized state.

[0226] The reverse polarization test data includes test data obtained by performing reverse electrochemical impedance spectroscopy and reverse potentiostatic polarization tests on the test battery pack with reverse polarization potential.

[0227] The reverse polarization potential is obtained using the polarization potential determination method described in the above embodiments.

[0228] Step S428: Correct the voltage in the reverse voltage change data to obtain the reverse polarization voltage. Based on the reverse polarization voltage, the second current change data, the third electrochemical impedance spectroscopy data, and the fourth electrochemical impedance spectroscopy data, determine the reverse ion migration number of each test battery pack.

[0229] In practice, this can be done on a per-test-battery-pack basis, extracting the initial current from the second current change data for each test-battery-pack. and steady-state current The true reverse polarization voltage can be obtained using formula (10). Then, the third electrochemical impedance spectroscopy data is fitted to obtain the third interfacial impedance before polarization. The fourth interfacial impedance after polarization was obtained by fitting the fourth electrochemical impedance spectroscopy data. Substituting the above parameters into formulas (4), (7), or (8), the ion migration values ​​for the reverse polarization test of each test battery pack can be obtained. .

[0230] Step S410: Based on the forward ion migration number and the reverse ion migration number, the target ion migration number of each test battery pack is obtained.

[0231] In this embodiment, it can be made ,like (This value is an empirical value and can be taken between 0.05 and 0.2 depending on the situation.) If this value is found to be abnormal, the reverse ion migration value of the test battery pack is considered to be abnormal. It should be related to the positive ion migration value Data from these parallel samples lack accuracy and should be discarded. Then determine the reverse ion mobility number of the test battery pack. It should be related to the positive ion transference number Normally, ultimately, the target ion migration value t for the test battery pack was determined to be the reverse ion migration value. It should be related to the positive ion migration value The average value, i.e. .

[0232] Step S432: Obtain polarization verification data of the test battery pack. The polarization verification data includes reverse verification polarization voltage, third current change data, and fifth electrochemical impedance spectroscopy data under polarization state. Correct the voltage in the reverse verification voltage change data to obtain the reverse verification polarization voltage. Based on the reverse verification polarization voltage, third current change data, fourth electrochemical impedance spectroscopy data, and fifth electrochemical impedance spectroscopy data, determine the ion mobility number verification value of each test battery pack. Compare the ion mobility number verification value with the target ion mobility number. Based on the comparison results, screen out the target abnormal battery pack.

[0233] In practice, for each test battery pack, the initial current can be extracted from the third current change data. and steady-state current The true reverse polarization voltage can be obtained using formula (10). The fourth interfacial impedance before polarization was obtained by fitting the fourth electrochemical impedance spectroscopy data. The interfacial impedance before polarization in this calculation Establish relationships: The fifth electrochemical impedance spectroscopy data were fitted to obtain the polarized fifth interfacial resistance. Substituting the above parameters into formulas (4), (7), or (8), the ion mobility number verification value for each test battery pack can be obtained. .

[0234] Then, compare the ion mobility number verification values. and target ion mobility number verification value ,make ,like If the battery assembly and test data and results for that group are deemed normal, then it is determined that there are no abnormalities. If any abnormality is found in the battery assembly, test data, and test results of that test battery group, it will be determined that the test battery group is abnormal. Following this method, each battery group under test will be compared to select the appropriate test battery group. Furthermore, an anomaly handling message can be sent so that testers can promptly identify and correct the problem.

[0235] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0236] To address the issue of inaccurate electrolyte ion transport number test results, this application also provides a coin cell device for performing electrolyte ion transport number tests.

[0237] like Figure 12 As shown, based on the same inventive concept, this application embodiment also provides an electrolyte ion transport number testing system, the system including a testing device 202 and a testing control device 204 connected to each other;

[0238] The test control device 204 is used to implement the electrolyte ion mobility number test method described in any of the above embodiments to test the ion mobility number of the test device 202 and obtain the ion mobility number of the test device 202.

[0239] In this embodiment, the testing device 202 can be a reusable battery device or a disposable battery device; any device commonly used for testing ion mobility numbers can be used as the testing device. The testing control device 204 can be a device with both data processing and testing capabilities, capable of performing constant potential polarization testing and EIS testing on the testing device 202, and also measuring the ion mobility number based on the test data. Alternatively, it can be a device with only data processing capabilities, receiving test data and verification data transmitted from an external detection device to perform the ion mobility number test. Specifically, the ion mobility number test can be performed using the electrolyte ion mobility number testing method described in any of the above embodiments to obtain the ion mobility number of the testing device 202.

[0240] In the technical solution of this application embodiment, by providing the above-mentioned electrolyte ion mobility number testing system, the electrolyte ion mobility number of the testing device can be measured quickly and accurately.

[0241] In some embodiments, the test apparatus 202 includes a button battery device 100.

[0242] like Figure 13 As shown, the button cell device 100 includes a separator 102 and an insulating adhesive layer 104 with through holes. The insulating adhesive layer 104 is provided with through holes, and the separator 102 is embedded in the through holes. The difference between the inner diameter and the outer diameter of the insulating adhesive layer 104 is a target value. The target value is used to make the detection area of ​​the button cell device 100 the separator 102 without the insulating adhesive layer 104.

[0243] In this embodiment, the button cell battery device 100 is a non-removable battery assembled using the button cell technology. The separator 102 is a limiting separator, that is, a limiting separator is used to limit the passage. The insulating adhesive layer 104 102 is provided with through holes. In this embodiment, the insulating adhesive layer 104 can be an annular structure with an outer diameter of 18 mm and an inner diameter of 12 mm, attached to both sides of the separator 102 to ensure that the effective detection area of ​​the electrode sheet is the separator 102 without the insulating adhesive layer 104, so as to achieve a perfect symmetry between the positive and negative electrode sheets. The insulating adhesive layer 104 is usually green insulating adhesive. It is understood that in other embodiments, the outer diameter and inner diameter of the insulating adhesive layer 104 are not limited to the above example. In other embodiments, they can also be other sizes, as long as they can satisfy the requirement that the effective detection area of ​​the button cell battery device is the separator 102 without the insulating adhesive layer 104, achieving a perfect symmetry between the positive and negative electrode sheets.

[0244] Specifically, in addition to the insulating adhesive layer 104 and the separator 102, the button cell device also includes a positive electrode casing, a negative electrode casing, a positive electrode sheet, a negative electrode sheet, and catalytic materials, etc. Figure 14(Not provided). Taking a coin cell lithium battery as an example, the specific assembly process is as follows: place the negative electrode shell, add the filler, compact the filler, add lithium foil, inject 80 μL of electrolyte, add the positioning separator, inject 80 μL of electrolyte, add another lithium foil, attach the positive electrode shell, and finally seal the coin cell. In practice, to ensure that the separator and lithium foil surfaces are fully wetted, after assembly, the battery can be left to stand at room temperature for a period of time, such as 12 hours, before starting the ion migration number test. In this embodiment, to ensure test consistency, the sealing press is uniformly used with a pressure of 500 mPa for sealing the coin cells.

[0245] In the technical solution of this application embodiment, by providing a coin cell device in which the separator is embedded in the through hole of the insulating adhesive layer and the difference between the inner diameter and the outer diameter of the insulating adhesive layer is a specific target value, the effective detection area of ​​the coin cell device is the separator without the insulating adhesive layer, achieving the effect of perfect symmetry of the positive and negative electrode plates, thereby improving the accuracy and consistency of the ion mobility number test results.

[0246] In addition, button cell battery devices can also be made into non-removable disposable battery devices, which can effectively solve the aforementioned contradiction between sealing and disassembly.

[0247] In other embodiments, the filler of the button cell device 100 includes nickel foam.

[0248] In this embodiment, the filler for the button cell device is selected as nickel foam, which has good permeability and filtration properties. Specifically, the diameter of the nickel foam can also be 18 mm. It is understood that in other embodiments, the filler can also be other types of catalytic materials, and the diameter can also be other values, as long as the outer diameter of the insulating adhesive layer is equal.

[0249] In the technical solution of this application embodiment, by selecting nickel foam as the filler for the button cell device, the effect of full contact between the separator and the positive and negative electrode sheets can be achieved.

[0250] In the technical solution of this application embodiment, by using a coin cell device as a testing device, the accuracy and consistency of ion mobility number test results can be further improved.

[0251] In some embodiments, the test control device 204 is further configured to perform electrochemical impedance spectroscopy on the test device 202 at a test frequency not lower than the target cutoff frequency, the target cutoff frequency being used to maintain the steady state of the test device.

[0252] Currently, the commonly used EIS test frequency is 300MHz~100mHz. However, research has found that when the EIS test frequency is less than 1Hz, a large Faraday current exists during the test, which significantly affects the solid-liquid interface impedance. Therefore, the cutoff frequency of the EIS test can be adjusted. In this embodiment, the target cutoff frequency can be 1Hz. In actual ion mobility number testing experiments, the EIS test frequency used can be 300MHz~1Hz. It is understood that in other embodiments, the target cutoff frequency can also be other values ​​such as 1.1Hz, 1.01Hz, etc., depending on the actual situation, as long as the steady state of the test device can be maintained. In specific implementation, the test control device 204 can directly perform EIS testing on the test device 202 according to the preset EIS test frequency, or the test control device 204 can send a test signal carrying the EIS test frequency to an external detection device, so that the external detection device can perform EIS testing on the test device 202 according to the corresponding EIS test frequency.

[0253] Based on the same inventive concept, this application also provides a polarization battery determination apparatus for implementing the polarization battery determination method described above, and an electrolyte ion mobility number testing apparatus for implementing the electrolyte ion mobility number testing method described above. The solution provided by this apparatus is similar to the solution described in the above method; therefore, the specific limitations in one or more embodiments of the polarization battery determination apparatus and electrolyte ion mobility number testing apparatus provided below can be found in the limitations of the polarization battery determination method and ion mobility number testing described above, and will not be repeated here.

[0254] In some embodiments, such as Figure 14 As shown, a polarization potential determination device is provided, comprising: a data acquisition module 710, a data fitting module 720, and a target polarization potential determination module 730, wherein:

[0255] The data acquisition module 710 is used to acquire the current density change data obtained by constant potential polarization test of the test battery pack with different polarization potentials.

[0256] The data fitting module 720 is used to fit the current density change data to obtain the fitting parameters corresponding to different polarization potentials.

[0257] The target polarization potential determination module 730 is used to determine the target polarization potential of the test battery pack based on the fitted parameters. The target polarization potential is used to maintain the steady state of the test battery pack.

[0258] In the technical solution of this application embodiment, the current density change data obtained by performing constant potential polarization tests on the test battery pack with different polarization potentials are fitted to obtain fitting parameters corresponding to different polarization potentials. Then, based on the fitting parameters, the target polarization potential that enables the test battery pack to maintain a steady state under polarization is determined. This process differs from the traditional method of using a universal fixed value for constant potential polarization testing. By fitting the current density change data corresponding to different polarization potentials, the target polarization potential that enables the test battery pack to maintain a steady state under polarization can be determined specifically. This allows for the targeted determination of the optimal polarization potential for the test battery pack and supports constant potential polarization testing using this target polarization potential, resulting in more accurate measured ion transference numbers.

[0259] In some embodiments, the data fitting module 720 is further configured to perform curve fitting processing on the current density change data to obtain fitting parameters.

[0260] In some embodiments, the data fitting module 720 is further configured to select target current density change data within a preset time range from the current density change data, perform linear regression fitting on the target current density change data, and obtain linear regression fitting parameters.

[0261] In some embodiments, the target polarization potential determination module 730 is further configured to compare the linear regression fitting parameters with preset linear coefficients, and determine the target polarization potential of the test battery pack based on the comparison results and preset polarization potential selection rules.

[0262] In some embodiments, such as Figure 15 As shown, an electrolyte ion transport number testing device is provided. The device includes:

[0263] The test data acquisition module 810 is used to acquire the forward polarization test data of the test battery pack. The forward polarization test data includes test data obtained by performing electrochemical impedance spectroscopy and constant potential polarization tests on the test battery pack with forward polarization potential.

[0264] The forward ion migration number determination module 820 is used to determine the forward ion migration number of each test battery pack based on the forward polarization test data.

[0265] The positive polarization potential is obtained using the polarization potential determination method described in the above embodiments.

[0266] In the technical solution of this application embodiment, by fitting the current density change data corresponding to different polarization potentials, the positive polarization potential that enables the test battery pack to maintain a steady state under polarization is determined. Then, based on the test data obtained by performing electrochemical impedance spectroscopy and constant potential polarization tests on the test battery pack with the positive polarization potential, the positive ion migration number is determined, which can obtain a more accurate positive ion migration number.

[0267] like Figure 16 As shown, in some embodiments, the electrolyte ion mobility number testing device further includes a target ion mobility number determination module 830, used to acquire reverse polarization test data of the test battery pack. The reverse polarization test data includes test data obtained by performing reverse electrochemical impedance spectroscopy and reverse potentiostatic polarization tests on the test battery pack with reverse polarization potential. Based on the reverse polarization test data, the reverse ion mobility number of each test battery pack is determined, and the target ion mobility number of each test battery pack is obtained based on the forward ion mobility number and the reverse ion mobility number. The reverse polarization potential is obtained using the polarization potential determination method described in the above embodiments.

[0268] In some embodiments, the forward polarization test data includes forward voltage change data, first current change data, first electrochemical impedance spectroscopy data in the open circuit state, and second electrochemical impedance spectroscopy data in the polarized state.

[0269] The forward ion migration number determination module 820 is also used to correct the voltage in the forward voltage change data to obtain the forward polarization voltage, and to determine the forward ion migration number of each test battery pack based on the forward polarization voltage, the first current change data, the first electrochemical impedance spectroscopy data and the second electrochemical impedance spectroscopy data.

[0270] In some embodiments, the reverse polarization test data includes reverse voltage change data, second current change data, third electrochemical impedance spectroscopy data under polarized state and fourth electrochemical impedance spectroscopy data under open circuit state.

[0271] The target forward ion migration number determination module 830 is also used to correct the voltage in the reverse voltage change data to obtain the reverse polarization voltage, and determine the reverse ion migration number of each test battery pack based on the reverse polarization voltage, the second current change data, the third electrochemical impedance spectroscopy data, and the fourth electrochemical impedance spectroscopy data.

[0272] like Figure 16As shown, in some embodiments, the electrolyte ion mobility number testing device further includes an ion mobility number verification value determination module 840, which is used to acquire polarization verification data of the test battery pack. The polarization verification data includes data obtained by performing electrochemical impedance spectroscopy and constant potential polarization tests on the test battery pack with a reverse verification polarization potential. Based on the polarization verification data and the reverse polarization test data, the ion mobility number verification value of each test battery pack is determined. The ion mobility number verification value is compared with the target ion mobility number. Based on the comparison results, the target abnormal battery pack is screened out.

[0273] In some embodiments, the reverse polarization test data includes fourth electrochemical impedance spectroscopy data in the open-circuit state, and the polarization verification data includes reverse verification voltage change data, third current change data, and fifth electrochemical impedance spectroscopy data in the polarized state.

[0274] The ion mobility number verification value determination module 840 is also used to correct the voltage in the reverse verification voltage change data to obtain the reverse verification polarization voltage. Based on the reverse verification polarization voltage, the third current change data, the fourth electrochemical impedance spectroscopy data, and the fifth electrochemical impedance spectroscopy data, the ion mobility number verification value of each test battery pack is determined.

[0275] Each module in the aforementioned polarization cell determination device and electrolyte ion transport number testing device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device in hardware form, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0276] In some embodiments, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 17As shown, the computer device includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When executed by the processor, the computer program implements a polarization cell determination method or an ion mobility number test method. The display unit is used to form a visually visible image and can be a display screen, a projection device, or a virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the computer device, or external keyboards, touchpads, or mice, etc.

[0277] Those skilled in the art will understand that Figure 17 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0278] In some embodiments, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described polarized cell determination method or electrolyte ion transport number test method.

[0279] In some embodiments, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above-described polarized cell determination method or electrolyte ion transport number test method.

[0280] In some embodiments, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above-described polarized cell determination method or electrolyte ion transport number test method.

[0281] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant countries and regions.

[0282] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0283] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for determining polarization potential, characterized in that, The method includes: Obtain current density variation data from constant potential polarization tests on the test battery pack with different polarization potentials; The current density variation data is fitted to obtain fitting parameters corresponding to different polarization potentials; the fitting process includes: arranging the current density variation data under different polarization potentials according to the horizontal axis... The ordinate is fitted using current density to obtain j~ under different polarization potentials. Curve, where j is the current density, For time; Based on the fitting parameters, the target polarization potential of the test battery pack is determined, and the target polarization potential is used to maintain the steady state of the test battery pack. The fitting parameters include linear coefficients. Determining the target polarization potential of the test battery pack based on these fitting parameters includes: setting the linear coefficients to be greater than a preset linear coefficient, j~ The curve is There are no abnormal inflection points, the relationship is linear, and j~ The curve is When the current does not rise abnormally when it approaches 0, the corresponding polarization potential is taken as the target polarization potential.

2. The method for determining polarization potential according to claim 1, characterized in that, The method further includes: Select target current density change data within a preset time range from the current density change data; Linear regression fitting is performed on the target current density change data to obtain the linear regression fitting parameters.

3. The method for determining polarization potential according to claim 2, characterized in that, Determining the target polarization potential of the test battery pack based on the fitted parameters includes: The linear regression fitting parameters are compared with preset linear coefficients; Based on the comparison results and the preset polarization potential selection rules, the target polarization potential of the test battery pack is determined.

4. A method for testing the ion transport number of an electrolyte, characterized in that, The method includes: Obtain forward polarization test data of the test battery pack, including test data obtained by performing electrochemical impedance spectroscopy and constant potential polarization tests on the test battery pack with forward polarization potential. Based on the positive polarization test data, the number of positive ion migrations for each test battery pack is determined; The positive polarization potential is obtained using the polarization potential determination method as described in any one of claims 1 to 3.

5. The method for testing the electrolyte ion transport number according to claim 4, characterized in that, After determining the forward ion migration number of each test battery pack, the method further includes: Obtain the reverse polarization test data of the test battery pack, which includes test data obtained by performing reverse electrochemical impedance spectroscopy and reverse potentiostatic polarization tests on the test battery pack with reverse polarization potential. Based on the reverse polarization test data, the reverse ion migration number of each test battery pack is determined; The target ion migration number for each test battery pack is obtained based on the forward ion migration number and the reverse ion migration number. The reverse polarization potential is obtained using the polarization potential determination method as described in any one of claims 1 to 3.

6. The method for testing the ion transport number of an electrolyte according to claim 4, characterized in that, The forward polarization test data includes forward voltage change data, first current change data, first electrochemical impedance spectroscopy data under open circuit state, and second electrochemical impedance spectroscopy data under polarization state. The determination of the forward ion migration number for each test battery pack based on the forward polarization test data includes: The voltage in the positive voltage change data is corrected to obtain the positive polarization voltage; The forward ion migration number of each test battery pack is determined based on the forward polarization voltage, the first current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data.

7. The method for testing the ion transport number of an electrolyte according to claim 5, characterized in that, The reverse polarization test data includes reverse voltage change data, second current change data, third electrochemical impedance spectroscopy data under polarization state, and fourth electrochemical impedance spectroscopy data under open circuit state. The determination of the reverse ion transport number for each test battery pack based on the reverse polarization test data includes: The voltage in the reverse voltage change data is corrected to obtain the reverse polarization voltage; The reverse ion migration number of each test battery pack is determined based on the reverse polarization voltage, the second current change data, the third electrochemical impedance spectroscopy data, and the fourth electrochemical impedance spectroscopy data.

8. The method for testing the ion transport number of an electrolyte according to claim 5, characterized in that, After obtaining the target ion mobility numbers for each test battery pack, the method further includes: Obtain polarization verification data of the test battery pack, the polarization verification data including data obtained by performing electrochemical impedance spectroscopy and potentiostatic polarization tests on the test battery pack with reverse verification polarization potential; Based on the polarization verification data and the reverse polarization test data, determine the ion migration number verification value for each test battery pack; By comparing the verified ion mobility number with the target ion mobility number, the target abnormal battery packs are selected based on the comparison results.

9. The method for testing the ion transport number of an electrolyte according to claim 8, characterized in that, The reverse polarization test data includes the fourth electrochemical impedance spectroscopy data under the open circuit state, and the polarization verification data includes the reverse verification voltage change data, the third current change data, and the fifth electrochemical impedance spectroscopy data under the polarization state. The determination of the ion mobility number verification value for each test battery pack based on the polarization verification data and the reverse polarization test data includes: The voltage in the reverse verification voltage change data is corrected to obtain the reverse verification polarization voltage; Based on the reverse verification polarization voltage, the third current change data, the fourth electrochemical impedance spectroscopy data, and the fifth electrochemical impedance spectroscopy data, the ion mobility number verification value for each test battery pack is determined.

10. An electrolyte ion transport number testing system, the system comprising a testing device and a testing control device interconnected with each other; The test control device is used to perform ion mobility number testing of the test device using the electrolyte ion mobility number testing method as described in any one of claims 4-9, and to obtain the ion mobility number of the test device.

11. The system according to claim 10, characterized in that, The testing device includes a button battery device.

12. The system according to claim 11, characterized in that, The button cell device includes a separator and an insulating adhesive layer with through holes. The separator is embedded in the through holes. The difference between the inner diameter and the outer diameter of the insulating adhesive layer is a target value. The target value is used to make the detection area of ​​the button cell device a separator without the insulating adhesive layer covering it.

13. The system according to any one of claims 10 to 12, characterized in that, The test control device is also used to perform electrochemical impedance spectroscopy tests on the test device at a test frequency not lower than the target cutoff frequency, wherein the target cutoff frequency is used to maintain the steady state of the test device.

14. A polarization potential determination device, characterized in that, The device includes: The data acquisition module is used to acquire current density change data obtained by constant potential polarization test of the test battery pack with different polarization potentials; The data fitting module is used to perform fitting processing on the current density variation data to obtain fitting parameters corresponding to different polarization potentials; the fitting processing includes: dividing the current density variation data under different polarization potentials according to the horizontal axis. The ordinate is fitted using current density to obtain j~ under different polarization potentials. Curve, where j is the current density, For time; The target polarization potential determination module is used to determine the target polarization potential of the test battery pack based on the fitting parameters, and the target polarization potential is used to maintain the steady state of the test battery pack. The fitting parameters include linear coefficients, and the target polarization potential determination module is further configured to: set the linear coefficients to be greater than a preset linear coefficient, j~ The curve is There are no abnormal inflection points, the relationship is linear, and j~ The curve is When the current does not rise abnormally when it approaches 0, the corresponding polarization potential is taken as the target polarization potential.

15. An electrolyte ion transport number testing device, characterized in that, The device includes: The test data acquisition module is used to acquire the forward polarization test data of the test battery pack. The forward polarization test data includes test data obtained by performing electrochemical impedance spectroscopy and constant potential polarization tests on the test battery pack with forward polarization potential. The forward ion migration number determination module is used to determine the forward ion migration number of each test battery pack based on the forward polarization test data. The positive polarization potential is obtained using the polarization potential determination method as described in any one of claims 1 to 3.

16. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1-3 or 4-9.

17. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1-3 or 4-9.

18. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the method according to any one of claims 1-3 or 4-9.

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