Electrolyte ion transport number testing methods, systems, apparatus and computer equipment

Abstract

This application relates to a method, system, apparatus, computer equipment, storage medium, and computer program product for testing the ion transport number of an electrolyte, as well as a coin cell battery device. The method includes: acquiring test data obtained by sequentially performing constant potential polarization testing and electrochemical impedance spectroscopy (EIS) testing on a test battery pack at a test voltage. The test data includes voltage and current change data under constant potential polarization, first EIS data under polarization, and second EIS data under open-circuit conditions for each test battery pack. Based on the voltage change data, current change data, first EIS data, and second EIS data, the ion transport number of each test battery pack is determined. This method can obtain a more accurate ion transport number.

Description

Technical Field

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

[0002] 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.

[0003] 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 performance of lithium-ion batteries can be predicted by testing the lithium-ion transference number of the electrolyte. A higher lithium-ion transference coefficient is beneficial for reducing concentration polarization during charging and discharging, and is of great significance for improving the power density and energy density of lithium-ion batteries.

[0004] Currently, commonly used methods for testing electrolyte ion transport numbers include the constant potential polarization method (also known as the constant potential polarization method). However, the constant potential polarization method for testing ion transport numbers suffers from a problem of inaccurate initial current, resulting in low accuracy of the measured ion transport numbers. Summary of the Invention

[0005] Based on this, it is necessary to provide a method, system, apparatus, computer equipment, computer-readable storage medium, and computer program product for testing the lithium-ion mobility number of an electrolyte, which can improve the accuracy of the ion mobility number, as well as a coin cell battery device, to address the above-mentioned technical problems.

[0006] Firstly, this application provides a method for testing the ion transport number of an electrolyte. The method includes:

[0007] The test data obtained by sequentially performing constant potential polarization test and electrochemical impedance spectroscopy test on the test battery pack with the test voltage includes voltage change data and current change data under constant potential polarization state, first electrochemical impedance spectroscopy data under polarization state and second electrochemical impedance spectroscopy data under open circuit state for each test battery pack.

[0008] Based on voltage change data, current change data, first electrochemical impedance spectroscopy data, and second electrochemical impedance spectroscopy data, the ion transport number of each test battery group was determined.

[0009] In the technical solution of this application embodiment, by first performing a constant potential polarization test on the test battery pack and then performing an electrochemical impedance spectroscopy test, the possibility of a large instantaneous current in the constant potential polarization test caused by performing an electrochemical impedance spectroscopy test first, which could lead to a deviation in the accuracy of the current test, can be reduced. This allows for the measurement of accurate current change data under conditions without other influencing factors. Furthermore, based on the accurate current change data, voltage change data, first electrochemical impedance spectroscopy data, and second electrochemical impedance spectroscopy data, a more accurate ion transference number can be obtained.

[0010] In some embodiments, before determining the ion transport number of each test battery pack based on voltage change data, current change data, first electrochemical impedance spectroscopy data, and second electrochemical impedance spectroscopy data, the method further includes:

[0011] The voltage in the voltage change data is corrected to obtain the target polarization voltage;

[0012] Based on voltage change data, current change data, first electrochemical impedance spectroscopy data, and second electrochemical impedance spectroscopy data, the ion transport numbers of each test battery group were determined as follows:

[0013] Based on the target polarization voltage and current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data, the ion migration number of each test battery pack was determined.

[0014] In the technical solution of this application embodiment, by correcting the voltage, a more realistic polarization voltage is obtained, and then the ion transference number is determined based on the more realistic polarization voltage, which makes the measured ion transference number more accurate.

[0015] In some embodiments, voltage change data includes open-circuit voltage;

[0016] The voltage in the voltage change data is corrected to obtain the target polarization voltage, including:

[0017] Determine the average voltage based on voltage change data;

[0018] The target polarization voltage is obtained based on the average voltage and the open-circuit voltage.

[0019] In the technical solution of this application embodiment, by first taking the average value of the voltage value, and then using the difference between the average voltage value and the open circuit voltage as the target polarization voltage, a more accurate and reasonable polarization voltage can be obtained, and further, the measured ion transference number can be made more accurate.

[0020] In some embodiments, the current change data includes initial current and steady-state current;

[0021] Based on the target polarization voltage and current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data, the ion transport numbers of each test battery group were determined as follows:

[0022] The first and second electrochemical impedance spectroscopy data are fitted to obtain the first and second interface impedances.

[0023] The ion transport number of each test battery pack is determined based on the target polarization voltage, initial current, steady-state current, first interface impedance, and second interface impedance.

[0024] In the technical solution of this application embodiment, the voltage is corrected to obtain the true polarization voltage during the calculation of ion mobility number, and the influence of interface impedance on the test process is taken into account. Therefore, the ion mobility number determined subsequently is more accurate.

[0025] In some embodiments, the current change data includes initial current and steady-state current;

[0026] Based on the target polarization voltage and current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data, the ion transport numbers of each test battery group were determined as follows:

[0027] The first electrochemical impedance spectroscopy data is fitted to obtain the first interface impedance and the first ohmic impedance, and the second electrochemical impedance spectroscopy data is fitted to obtain the second interface impedance and the second ohmic impedance.

[0028] The ion transport number of each test battery pack is determined based on the target polarization voltage, initial current, steady-state current, first interface impedance, first ohmic impedance, second interface impedance, and second ohmic impedance.

[0029] In the technical solution of this application embodiment, unlike the solution that only considers electrolyte impedance and interface impedance, the influence of ohmic impedance on the test process is also considered when calculating ion transport number, thus further improving the accuracy of ion transport number.

[0030] In some embodiments, the current change data includes initial current and steady-state current;

[0031] Based on the target polarization voltage and current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data, the ion transport numbers of each test battery group were determined as follows:

[0032] The first electrochemical impedance spectroscopy data is fitted to obtain the first interface impedance and the first ohmic impedance, and the second electrochemical impedance spectroscopy data is fitted to obtain the second interface impedance and the second ohmic impedance.

[0033] The first ohmic impedance and the second ohmic impedance are corrected according to the preset correction coefficient to obtain the first target ohmic impedance and the second target ohmic impedance.

[0034] The ion transference number of each test battery pack is determined based on the target polarization voltage, initial current, steady-state current, first interface impedance, first target ohmic impedance, second interface impedance, and second target ohmic impedance.

[0035] In the technical solution of this application embodiment, unlike the traditional approach of treating the electrolyte impedance as ohmic impedance and ignoring the impedance occupied by the membrane, the influence of the membrane impedance is taken into account in the actual test process, and the ohmic impedance is corrected by a correction factor to obtain a more accurate ion transference number.

[0036] In some embodiments, current change data includes initial current;

[0037] After determining the ion transport numbers of each test battery pack based on the target polarization voltage and current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data, the method further includes:

[0038] The second electrochemical impedance spectroscopy data were fitted to obtain the second ohmic impedance, SEI (Solid Electrolyte Interphase) impedance, and charge transfer impedance.

[0039] The voltage difference is obtained based on the target polarization voltage, the second ohmic impedance, the SEI impedance, the charge transfer impedance, and the initial current.

[0040] The voltage difference is compared with a preset voltage difference threshold to filter out abnormal battery packs. Abnormal battery packs are those with a voltage difference less than the preset voltage difference threshold.

[0041] Test data and ion migration counts of abnormal battery packs were removed.

[0042] In the technical solution of this application embodiment, abnormal battery packs are screened out by voltage difference, and the test data and ion migration number of abnormal battery packs are further eliminated, which can make the test data and test results more realistic.

[0043] In some embodiments, after removing test data and ion migration numbers from abnormal battery packs, the method further includes:

[0044] The verification data were obtained by performing constant potential polarization test and electrochemical impedance spectroscopy test on the test battery pack in sequence with the verification voltage. The verification data included voltage change verification data and current change verification data under constant potential polarization state of each test battery pack, as well as third electrochemical impedance spectroscopy data under polarization state.

[0045] The voltage in the voltage change verification data is corrected to obtain the target polarization voltage verification value;

[0046] Based on the polarization verification voltage and current change verification data, the third electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data, the ion transport number verification value of each test battery pack was determined.

[0047] By comparing the ion migration number and ion migration number verification value of each test battery pack, the target abnormal battery pack is selected based on the comparison results.

[0048] In the technical solution of this application embodiment, the verification data obtained by testing the test battery pack with the verification voltage is used to achieve cross-testing and verification of the test data and ion mobility number of the test battery pack, which ensures the consistency and repeatability of the test data and test results, and is more realistic and accurate.

[0049] Secondly, this application also provides a button cell device, which includes a separator and an insulating adhesive layer with through holes. The separator is embedded in the through holes, and 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.

[0050] 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.

[0051] In some embodiments, the filler of the button cell device includes nickel foam.

[0052] 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.

[0053] Thirdly, this application also provides an electrolyte ion transport number testing system, the system including a testing device and a testing control device connected to each other;

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

[0055] 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.

[0056] In some embodiments, the testing apparatus includes a non-removable battery device.

[0057] In the technical solution of this application embodiment, by designing the test device as a non-removable battery device, that is, without disassembling the battery, the adverse effects of disassembly on subsequent test results are reduced, and more accurate test results are obtained.

[0058] In some embodiments, the battery device includes a button battery device as described in the above embodiments.

[0059] 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.

[0060] 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.

[0061] In the technical solution of this application embodiment, by setting the target cutoff frequency, both the phase ohmic impedance and interface impedance can be completely tested, and the influence of Faraday current on the test results can be effectively reduced.

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

[0063] The data acquisition module is used to acquire test data obtained by sequentially performing constant potential polarization test and electrochemical impedance spectroscopy test on the test battery pack at the test voltage. The test data includes voltage change data and current change data of each test battery pack under constant potential polarization state, first electrochemical impedance spectroscopy data under polarization state and second electrochemical impedance spectroscopy data under open circuit state.

[0064] The ion mobility number determination module is used to determine the ion mobility number of each test battery pack based on the voltage change data, the current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data.

[0065] Fifthly, 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 electrolyte ion transport number testing method.

[0066] Sixthly, 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 electrolyte ion transport number testing method.

[0067] Seventhly, 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 electrolyte ion transport number testing method.

[0068] 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

[0069] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

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

[0071] Figure 2 This is a flowchart illustrating the electrolyte ion transport number testing method in some embodiments of this application;

[0072] Figure 3 This is a flowchart illustrating the electrolyte ion transport number testing method in other embodiments of this application;

[0073] Figure 4 This is a flowchart illustrating the steps for determining the ion transference number of each test battery pack in some embodiments of this application;

[0074] Figure 5 This is a flowchart illustrating the steps for determining the ion transference number of each test battery pack in other embodiments of this application;

[0075] Figure 6 This is a flowchart illustrating the steps for determining the ion transference number of each test battery pack in some embodiments of this application;

[0076] Figure 7 This is a flowchart illustrating the electrolyte ion transport number testing method in some embodiments of this application;

[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 detailed flowchart illustrating the electrolyte ion transport number testing method in some embodiments of this application;

[0079] Figure 10 This is a partial structural schematic diagram of the button battery device in some embodiments of this application;

[0080] Figure 11 This is a schematic diagram of the electrolyte ion transport number testing system in some embodiments of this application;

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

[0082] Figure 13 This is a structural block diagram of the electrolyte ion transport number testing device in some other embodiments of this application;

[0083] Figure 14 This is a diagram showing the internal structure of a computer device in some embodiments of this application. Detailed Implementation

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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 of the 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.

[0088] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0089] 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).

[0090] 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.

[0091] 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.

[0092] The traditional potentiostatic polarization method for ion transference number testing typically involves first performing EIS (Electrochemical Impedance Spectroscopy) on the test battery pack, followed by potentiostatic polarization testing, and finally, EIS testing under polarized conditions. However, this process introduces a significant instantaneous current, leading to inaccuracies in the measured initial current. Furthermore, to maintain a steady state during testing, a polarization voltage of 10 mV is generally used, and this voltage value is directly substituted into the transference number calculation formula. However, in actual testing, due to the influence of the electrochemical workstation channels or the battery assembly system, the open-circuit voltage of the test battery is often not 0 mV, and the actual voltage applied to the battery is often not equal to 10 mV. Therefore, the measured lithium-ion transference numbers are often inaccurate.

[0093] To improve the accuracy of ion transport number measurements, the order of the testing procedure can be adjusted to obtain a more accurate initial current. Specifically, a constant potential polarization test is performed first to obtain a relatively accurate initial current without the influence of other procedural factors. Then, electrochemical impedance spectroscopy (EIS) tests are conducted on the battery in both the polarized and steady-state states. Using the test data obtained from this procedure for ion transport number measurements yields more accurate results.

[0094] Based on the above considerations, this application provides a method for testing the ion transport number of an electrolyte, specifically including: acquiring test data obtained by sequentially performing constant potential polarization testing and electrochemical impedance spectroscopy (EIS) testing on a test battery pack at a test voltage; the test data includes voltage and current change data under constant potential polarization, first EIS data under polarization, and second EIS data under open circuit conditions for each test battery pack; then, determining the ion transport number of each test battery pack based on the voltage change data, current change data, first EIS data, and second EIS data. By performing constant potential polarization testing on the test battery pack first, followed by EIS testing, the possibility of a large instantaneous current during constant potential polarization testing, which could lead to deviations in the accuracy of current measurement, can be reduced. This allows for accurate current change data to be measured under conditions free from other influencing factors. Furthermore, based on the accurate current change data, voltage change data, first EIS data, and second EIS data, a more accurate ion transport number can be obtained.

[0095] The ion mobility number testing method provided in this application embodiment can 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 test data obtained by sequentially performing constant potential polarization tests and electrochemical impedance spectroscopy tests on the test battery pack at a test voltage. The test data includes voltage and current change data under constant potential polarization state, first electrochemical impedance spectroscopy data under polarization state, and second electrochemical impedance spectroscopy data under open circuit state for each test battery pack. Based on the voltage change data, current change data, first electrochemical impedance spectroscopy data, and second electrochemical impedance spectroscopy data, the ion transference number of each test battery pack is determined. The test battery pack 102 includes multiple battery packs, which can be general-purpose batteries, such as lithium batteries, or coin cells. The test data can be obtained by the test control device 104 directly testing the test battery pack 102, or by other testing instruments testing the test battery pack 102, depending on the actual situation, and is not limited here. The test control device 104 is a device with data processing capabilities.

[0096] In some embodiments, such as Figure 2 As shown, a method for measuring ion mobility number is provided, which is then applied to... Figure 1 The following steps are used as an example of the test control device 104:

[0097] Step S100: Obtain test data obtained by sequentially performing constant potential polarization test and electrochemical impedance spectroscopy test on the test battery pack at the test voltage. The test data includes voltage change data and current change data of each test battery pack under constant potential polarization state, first electrochemical impedance spectroscopy data under polarization state and second electrochemical impedance spectroscopy data under open circuit state.

[0098] Test voltage refers to the voltage used to test the test battery pack during the testing phase. 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. Voltage change data refers to the voltage changing over time, i.e., the voltage measured at each time point, including open-circuit voltage and polarization voltage. Current change data refers to the current changing over time, i.e., the current measured at each time point, including initial current and steady-state current. Electrochemical impedance spectroscopy (EIS) data is the test data obtained by performing EIS testing on the test battery pack. In this embodiment, the second electrochemical impedance spectroscopy data refers to the electrochemical impedance spectroscopy data obtained by performing EIS testing on the test battery pack in the polarized state after performing a constant potential polarization test on the test battery pack. The second electrochemical impedance spectroscopy data refers to the electrochemical impedance spectroscopy data collected by performing EIS testing on the test battery in the open-circuit state.

[0099] In practical applications, the test battery pack can first be left to stand for a period of time, such as 10 seconds. Then, a constant potential polarization test can be performed on the test battery pack using a commonly used test voltage, such as 10mV, for 10 minutes. During this process, voltage-time change data and current-time change data can be collected. Next, an EIS test can be performed on the test battery pack under the 10mV polarization state. In this embodiment, the test frequency of the EIS test can be 300MHz to 1Hz. During this process, the first electrochemical impedance spectroscopy data of each battery pack in the polarization state can be measured. Then, the battery pack can be left to stand for a period of time, such as 30 minutes, to allow the battery to return to a steady state under open circuit conditions. The EIS test can then be performed on the test battery pack again. During this process, the second electrochemical impedance spectroscopy data of each battery pack in the open circuit state can be measured. After performing ion mobility number tests on the test battery pack according to the above test procedure, the test data can be sent to the test control device. In specific implementations, the test data can be collected by the test control device itself during the test process, or it can be sent to the test control device by an external detection device. External testing devices can send test data to the test control device in real time, or they can send the obtained test data to the test control device in a unified manner after the test is completed.

[0100] Step S200: Determine the ion migration number of each test battery group based on voltage change data, current change data, first electrochemical impedance spectroscopy data, and second electrochemical impedance spectroscopy data.

[0101] Following the above embodiments, after obtaining the aforementioned test data, the ion mobility number of each test battery pack can be determined based on the ion mobility number testing principle, using voltage change data, current change data, first electrochemical impedance spectroscopy data, and second electrochemical impedance spectroscopy data. In specific implementation, the ion mobility number of each test battery pack can be determined on a per-pack basis, using voltage change data, current change data, first electrochemical impedance spectroscopy data, and second electrochemical impedance spectroscopy data.

[0102] In the technical solution of this application embodiment, by first performing a constant potential polarization test on the test battery pack and then performing an electrochemical impedance spectroscopy test, the possibility of a large instantaneous current in the constant potential polarization test caused by performing an electrochemical impedance spectroscopy test first, which could lead to a deviation in the accuracy of the current test, can be reduced. This allows for the measurement of accurate current change data under conditions without other influencing factors. Furthermore, based on the accurate current change data, voltage change data, first electrochemical impedance spectroscopy data, and second electrochemical impedance spectroscopy data, a more accurate ion transference number can be obtained.

[0103] like Figure 3As shown, in some embodiments, before step S200, the method further includes: step S120, correcting the voltage in the voltage change data to obtain the target polarization voltage.

[0104] Step S200 includes: Step S202, determining the ion migration number of each test battery pack based on the target polarization voltage and current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data.

[0105] The target polarization voltage refers to the corrected true polarization voltage of each test battery pack during the testing process. Currently, a polarization voltage of 10mV is generally used in ion mobility number testing to ensure the battery maintains a steady state as much as possible during the test. In subsequent ion mobility number calculations, the 10mV voltage value is usually 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 battery assembly system, the open-circuit voltage of the test battery is often not 0mV, and the applied true voltage is often not equal to 10mV. 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, the final measured ion mobility number will deviate from the true value. Therefore, in this embodiment, the polarization voltage of each test battery pack can be individually corrected to obtain the true target polarization voltage. Specifically, the correction method includes, but is not limited to, taking the average or maximum voltage value, or other correction processing.

[0106] After obtaining the target polarization voltage, the ion transference number of each test battery pack is obtained on a per-test battery pack basis, based on the corresponding target polarization voltage, initial current, steady-state current, interface impedance before polarization, and interface impedance after polarization.

[0107] In the technical solution of this application embodiment, by correcting the voltage, a more realistic polarization voltage is obtained, and then the ion transference number is determined based on the more realistic polarization voltage, which makes the measured ion transference number more accurate.

[0108] In some embodiments, step S120 includes: determining the average voltage based on voltage change data, and obtaining the target polarization voltage based on the average voltage and the open-circuit voltage.

[0109] In practical applications, voltage change data includes open-circuit voltage, which can be positive or negative. During actual testing, the open-circuit voltage of the 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 achieved by calculating the average voltage value from 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.

[0110] Specifically, record the open-circuit voltage value of the test battery pack under open-circuit conditions as U1, and take the average value of the voltage values ​​recorded during the test as U2. Then, the true target polarization voltage is ΔV:

[0111] ΔV=U2-U1 (1)

[0112] In the technical solution of this application embodiment, by first taking the average value of the voltage value, and then using the difference between the average voltage value and the open circuit voltage as the target polarization voltage, a more accurate and reasonable polarization voltage can be obtained, and further, the measured ion transference number can be made more accurate.

[0113] like Figure 4 As shown, in some embodiments, the current change data includes initial current and steady-state current;

[0114] Step S202 includes:

[0115] Step S204: Fit the first electrochemical impedance spectroscopy data and the second electrochemical impedance spectroscopy data to obtain the first interface impedance and the second interface impedance.

[0116] Step S206: Determine the ion migration number of each test battery pack based on the target polarization voltage, initial current, steady-state current, first interface impedance, and second interface impedance.

[0117] Specifically, the first and second electrochemical impedance spectroscopy (EIS) data can be fitted, such as through impedance fitting, to obtain the corresponding battery impedance data. This data can be either the first or second EIS curves. The first EIS curve includes data such as the first interface impedance, ohmic impedance, and charge transfer impedance after polarization. The second EIS data includes data such as the second interface impedance, ohmic impedance, and charge transfer impedance before polarization. After obtaining the battery impedance data, the target polarization voltage in the voltage change data can be further determined, and the initial current and steady-state current in the current change data can be extracted. Then, based on the target polarization voltage, initial current, steady-state current, the first EIS data, and the second EIS data, the lithium-ion transference number of each test battery pack can be determined.

[0118] Taking the testing of lithium-ion transference number as an example, the lithium-ion transference number can be determined in the following way:

[0119] Extract the initial current I0 and steady-state current I from the current change data. s If the effect of interface impedance on the testing process is not considered, then the lithium-ion mobility number t + for:

[0120] t+ =I s / I0 (2)

[0121] If we consider the influence of interface impedance on the testing process, then we have:

[0122] I0=ΔV / (R0+k / σ) (3)

[0123] I s =ΔV / (R) s +k / (t + σ)) (4)

[0124] In the formula, R0 is the second interface impedance before polarization, R s ΔV is the first interface impedance after polarization, k is the target polarization voltage, k is the electrolytic cell constant (length / surface area), and σ is the electrolyte conductivity.

[0125] In this embodiment, taking the influence of interface impedance on the testing process as an example, by combining formulas (2), (3), and (4), the formula for calculating the lithium-ion transference number can be obtained as follows:

[0126] t + =I s (ΔV-I0R0) / I0(ΔV-I s R s (5)

[0127] In practice, after obtaining the voltage change data, current change data, first electrochemical impedance spectroscopy data, and second electrochemical impedance spectroscopy data for each battery group, the target polarization voltage can be determined based on the voltage change data. The initial current and steady-state current in the current change data, the interfacial impedance before polarization in the first electrochemical impedance spectroscopy curve, and the interfacial impedance after polarization in the second electrochemical impedance spectroscopy curve are extracted respectively. Then, taking the test battery group as a unit, for each test battery group, its corresponding polarization voltage, initial current, steady-state current, interfacial impedance before polarization, and interfacial impedance after polarization are substituted into formula (5) to obtain the lithium-ion transference number of each test battery group. It should be noted that since the test battery group is subjected to constant potential polarization test first and then electrochemical impedance spectroscopy test in the actual test process, the initial current and steady-state current can be accurately measured under the condition of no other influencing factors, thus making the calculated ion transference number result more accurate.

[0128] In the technical solution of this application embodiment, the voltage is corrected to obtain the true polarization voltage during the calculation of ion mobility number, and the influence of interface impedance on the test process is taken into account. Therefore, the ion mobility number determined subsequently is more accurate.

[0129] like Figure 5As shown, in some embodiments, the current change data includes initial current and steady-state current;

[0130] Step S202 includes:

[0131] Step S224: Fit the first electrochemical impedance spectroscopy data to obtain the first interface impedance and the first ohmic impedance, and fit the second electrochemical impedance spectroscopy data to obtain the second interface impedance and the second ohmic impedance.

[0132] Step S226: Determine the ion transference number of each test battery pack based on the target polarization voltage, initial current, steady-state current, first interface impedance, first ohmic impedance, second interface impedance, and second ohmic impedance.

[0133] In this embodiment, the first and second electrochemical impedance spectroscopy (EIS) data can be fitted, such as through impedance fitting, to obtain corresponding first and second EIS curves. The first EIS curve includes data such as the first interface impedance after polarization, ohmic impedance, and charge transfer impedance. The second EIS data includes data such as the second interface impedance before polarization, ohmic impedance, and charge transfer impedance. After fitting the battery impedance data, the polarization voltage can be further extracted from the voltage change data, and the initial and steady-state currents from the current change data. The first interface impedance and first ohmic impedance can be extracted from the first EIS curve, and the second interface impedance and second ohmic impedance can be extracted from the second EIS curve. Based on the target polarization voltage, initial current, steady-state current, first interface impedance, second interface impedance, first ohmic impedance, and second ohmic impedance, the ion transport number of each test battery pack can be determined.

[0134] In this embodiment, the influence of interface impedance and ohmic impedance on the test process is considered simultaneously, that is, the above formulas (3) and (4) need to be adjusted. The adjusted formulas are as follows:

[0135] I0=ΔV / (R0+R s，0 +k / σ) (6)

[0136] I s =ΔV / (R) s +R s，s +k / (t + σ)) (7)

[0137] In the formula, R s，0 R is the second ohmic impedance measured in the EIS test before polarization. s，s This is the first ohmic impedance measured during the EIS test after polarization.

[0138] Combining formulas (2), (6), and (7), we have:

[0139]

[0140] In practice, the test battery pack can be used as a unit. For each test battery pack, its 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 (8) to obtain the ion migration number of each test battery pack.

[0141] In the technical solution of this application embodiment, unlike the solution that only considers electrolyte impedance and interface impedance, the influence of ohmic impedance on the test process is also considered when calculating ion transport number, thus further improving the accuracy of ion transport number.

[0142] like Figure 6 As shown, in some embodiments, the current change data includes initial current and steady-state current;

[0143] Step S202 includes:

[0144] Step S224: Fit the first electrochemical impedance spectroscopy data to obtain the first interface impedance and the first ohmic impedance, and fit the second electrochemical impedance spectroscopy data to obtain the second interface impedance and the second ohmic impedance.

[0145] Step S225: Correct the first ohmic impedance and the second ohmic impedance according to the preset correction coefficient to obtain the first target ohmic impedance and the second target ohmic impedance.

[0146] Step S246: Determine the ion transference number of each test battery pack based on the target polarization voltage, initial current, steady-state current, first interface impedance, first target ohmic impedance, second interface impedance, and second target ohmic impedance.

[0147] In actual testing, since membrane impedance is often difficult to measure directly, its influence on ion mobility number testing is often ignored. In the previous embodiment, the influence of membrane impedance on the testing process was ignored when considering ohmic impedance; following this approach may still result in some calculation errors. Therefore, this embodiment proposes a method to correct the first and second ohmic impedances.

[0148] Specifically, the process can begin by performing an open-circuit EIS test on symmetrical cells containing different numbers of separators, such as 1, 3, 5, and 7 layers. The test frequency can be 300MHz to 100mHz. Test data from the EIS test is collected. Then, the ohmic impedance is extracted from the test data, and the extracted ohmic impedance is fitted, such as using a univariate linear fitting, to obtain fitting parameters a and b. Based on the fitting parameters a and b, a correction coefficient z is determined, and this correction coefficient is then preset. The method for determining the correction coefficient z based on the fitting parameters a and b can be as follows:

[0149]

[0150] Then, the above formula (8) can be modified to obtain the following formula:

[0151]

[0152] In the formula, z is the correction coefficient. Extensive experimental data shows that, in this embodiment, z can be set to 0.1206.

[0153] In practice, each tested battery pack 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 zR. s,s Second target ohmic impedance zR s,0 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 (10) to obtain the ion transference number of each test battery pack.

[0154] In the technical solution of this application embodiment, unlike the traditional approach of treating the electrolyte impedance as ohmic impedance and ignoring the impedance occupied by the membrane, the influence of the membrane impedance is taken into account in the actual test process, and the ohmic impedance is corrected by a correction factor to obtain a more accurate ion transference number.

[0155] like Figure 7 As shown, in some embodiments, after step S202, the method further includes:

[0156] Step S300: Fit the second electrochemical impedance spectroscopy data to obtain the second ohmic impedance, SEI impedance, and charge transfer impedance. Based on the target polarization voltage, the second ohmic impedance, SEI impedance, charge transfer impedance, and initial current, obtain the voltage difference. Compare the voltage difference with a preset voltage difference threshold to screen out abnormal battery groups. Abnormal battery groups are those with a voltage difference less than the preset voltage difference threshold. Remove the test data and ion transport number of abnormal battery groups.

[0157] In practical applications, test data is often affected by various factors, leading to anomalies in the test data of different battery packs. Therefore, the measured test data and results can be filtered to identify anomalies. In this embodiment, anomalies are identified by the voltage difference of each test battery pack. Specifically, the voltage in the voltage change data can be corrected using the method described in the above embodiment for determining the target polarization voltage, resulting in the target polarization voltage ΔV. Then, the second electrochemical impedance spectroscopy data is fitted to extract the second ohmic impedance, SEI impedance, and charge transfer impedance. Based on the target polarization voltage, second ohmic impedance, SEI impedance, charge transfer impedance, and initial current, the voltage difference is obtained. Specifically, the voltage difference can be determined using the following formula:

[0158] ΔV′=ΔV-I0*(R s，0 +R f +R ct (11)

[0159] Where ΔV′ is the voltage difference, ΔV is the target polarization voltage, and R s，0 R is the second ohmic impedance measured by EIS under non-polarized conditions. f R is the SEI impedance. ct This represents the charge transfer impedance.

[0160] Typically, the voltage difference ΔV′ calculated by formula (11) is greater than x. Multiple tests have shown that if ΔV′ of a certain test battery pack is less than 1.0mV, the test data of that test battery pack often deviates significantly from the test data of other parallel test battery packs. However, when ΔV′ is greater than or equal to 1.0mV, the test data of that test battery pack shows good consistency with the test data of other parallel test battery packs. Therefore, in this embodiment, the voltage difference threshold can be set to 1.0mV. It is understood that in other embodiments, the voltage difference threshold can also be 1.1mV, 1.2mV, or other values, depending on the actual situation, and is not limited here.

[0161] After determining the voltage difference of each test battery pack, the voltage difference can be compared with a preset voltage threshold of 1.0mV. If the voltage difference is greater than or equal to 1.0mV, it indicates that the test data of this test battery pack has good consistency with the test data of other test battery packs, and no processing is required. If the voltage difference is less than 1.0mV, the test battery packs with voltage differences less than 1.0mV are selected and marked as abnormal battery packs. The corresponding test data and ion migration number of the abnormal battery packs are then deleted.

[0162] In the technical solution of this application embodiment, abnormal battery packs are screened out by voltage difference, and the test data and ion migration number of abnormal battery packs are further eliminated, which can make the test data and test results more realistic.

[0163] like Figure 8 As shown, in some embodiments, after step S300, the method further includes:

[0164] Step S400: Obtain verification data by sequentially performing constant potential polarization test and electrochemical impedance spectroscopy test on the test battery pack at the verification voltage. The verification data includes voltage change verification data and current change verification data under constant potential polarization state of each test battery pack, as well as third electrochemical impedance spectroscopy data under polarization state. Correct the voltage in the voltage change verification data to obtain the target polarization voltage verification value. Based on the polarization verification voltage, current change verification data, third electrochemical impedance spectroscopy data, and second electrochemical impedance spectroscopy data, determine the ion migration number verification value of each test battery pack. Compare the ion migration number and ion migration number verification value of each test battery pack. Based on the comparison results, screen out the target abnormal battery pack.

[0165] The verification voltage is a voltage value different from the test voltage used to verify the accuracy of the test results. In this embodiment, the verification voltage is 15mV as an example. It is understood that in other embodiments, the verification voltage can be other voltage values, depending on the actual situation. In this embodiment, the verification data is the data obtained by continuing to perform constant potential polarization test and EIS test on the same test battery pack again with the verification voltage on the original test procedure to verify the accuracy of the test results. Accordingly, the verification data includes voltage change verification data and current change verification data of each test battery pack under constant potential polarization state, as well as third electrochemical impedance spectroscopy data under polarization state. After obtaining the verification data, the voltage in the voltage change verification data can be corrected first to obtain the target polarization voltage verification value ΔV". Based on the target polarization verification voltage value, current change verification data, third electrochemical impedance spectroscopy data, and the previously obtained second electrochemical impedance spectroscopy data, the ion migration number verification value of each test battery pack can be determined. Specifically, the initial verification current can be extracted from the current change verification data. and steady-state verification current The third electrochemical impedance spectroscopy was fitted to extract the third interface impedance from the impedance data. and the third ohmic impedance In addition, consider the second interface impedance R0 and the second ohmic impedance R s，0 Substituting the various formulas into the following formula (12), we obtain the ion mobility number verification value under a 15mV test:

[0166]

[0167] Then, the ion mobility t of each test battery pack was compared at a test voltage of 10 mV and a verification voltage of 15 mV. + (The ion mobility number verification value t is obtained by formula (10)) + If the ion transport number t of the test battery pack is... + ion transport number verification value t + If the difference between ' and ' is within the allowable error range, such as ±0.05, it indicates that the test data and ion transport number of the test battery pack are not abnormal, and the test battery pack is a normal battery pack. If the ion transport number t of the test battery pack... + Verification value t of ion transport number + If the difference between the values ​​is not within the allowable error range (e.g., ±0.05), it indicates a significant data discrepancy in the test battery pack. This test battery pack can be marked as a target abnormal battery pack so that testers can promptly identify the cause of the anomaly and make adjustments and improvements. It is understood that the above-described method for verifying ion mobility numbers is only an example. In other embodiments, the calculation of the ion mobility number verification value can also be obtained using the test principles of formulas (5), (8), or (10). Similarly, the reference ion mobility number needs to be obtained using the same test principle as the ion mobility number verification value. In other embodiments, the average value of the ion mobility number verification values ​​of the test battery pack can be taken first, and then the ion mobility number of each test battery pack can be compared with the average value of the ion mobility number verification values. If the difference between the two is not within the allowable error range, the test battery pack is marked as a target abnormal battery pack. It is understood that in other embodiments, other comparison methods can also be used.

[0168] In the technical solution of this application embodiment, the verification data obtained by testing the test battery pack with the verification voltage is used to achieve cross-testing and verification of the test data and ion mobility number of the test battery pack, which ensures the consistency and repeatability of the test data and test results, and is more realistic and accurate.

[0169] To provide a clearer explanation of the electrolyte ion transport number testing method provided in this application, the following is in conjunction with the appendix. Figure 9 and one A specific embodiment will be described below, which includes the following steps:

[0170] Step S100: Obtain test data obtained by sequentially performing constant potential polarization test and electrochemical impedance spectroscopy test on the test battery pack at the test voltage. The test data includes voltage change data and current change data of each test battery pack under constant potential polarization state, first electrochemical impedance spectroscopy data under polarization state and second electrochemical impedance spectroscopy data under open circuit state.

[0171] Step S122: Based on the voltage change data, determine the average voltage value, and obtain the target polarization voltage based on the average voltage value and the open circuit voltage.

[0172] Step S224: Fit the first electrochemical impedance spectroscopy data to obtain the first interface impedance and the first ohmic impedance, and fit the second electrochemical impedance spectroscopy data to obtain the second interface impedance and the second ohmic impedance.

[0173] Step S225: Correct the first ohmic impedance and the second ohmic impedance according to the preset correction coefficient to obtain the first target ohmic impedance and the second target ohmic impedance.

[0174] Step S246: Determine the ion transference number of each test battery pack based on the target polarization voltage, initial current, steady-state current, first interface impedance, first target ohmic impedance, second interface impedance, and second target ohmic impedance.

[0175] Step S300: Fit the second electrochemical impedance spectroscopy data to obtain the second ohmic impedance, SEI impedance, and charge transfer impedance. Based on the target polarization voltage, the second ohmic impedance, SEI impedance, charge transfer impedance, and initial current, obtain the voltage difference. Compare the voltage difference with a preset voltage difference threshold to screen out abnormal battery packs. Remove the test data and ion migration number of abnormal battery packs. Abnormal battery packs are those with a voltage difference less than the preset voltage difference threshold.

[0176] Step S400: Obtain verification data by sequentially performing constant potential polarization test and electrochemical impedance spectroscopy test on the test battery pack at the verification voltage. The verification data includes voltage change verification data and current change verification data under constant potential polarization state of each test battery pack, as well as third electrochemical impedance spectroscopy data under polarization state. Correct the voltage in the voltage change verification data to obtain the target polarization voltage verification value. Based on the polarization verification voltage, current change verification data, third electrochemical impedance spectroscopy data, and second electrochemical impedance spectroscopy data, determine the ion migration number verification value of each test battery pack. Compare the ion migration number and ion migration number verification value of each test battery pack to screen out the target abnormal battery pack.

[0177] Specifically, the ion mobility number and the ion mobility number verification value can also be calculated based on the test principle of formulas (4), (8), (10), or (12). The test voltage is taken as 10mV, and the verification voltage can be taken as 15mV. The voltage difference threshold can be 1.0mV. The allowable error range between the ion mobility number and the ion mobility number verification value can be ±0.05.

[0178] 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.

[0179] Currently, in the field of electrolyte ion mobility number testing, the test results are often inaccurate. One significant contributing factor is the defective testing device. Commonly used electrolyte ion mobility number testing devices are typically reusable electrolytic cells, creating a dilemma regarding sealing and disassembly. Good sealing makes disassembly difficult or may cause permanent damage to the electrolytic cell, leading to errors in subsequent tests; poor sealing allows air to enter the device during testing, causing oxidation of the active material and resulting in inaccurate results. Furthermore, the inaccuracy of electrolyte ion mobility number testing devices also stems from the possibility of imperfect alignment of the positive and negative electrode plates.

[0180] 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.

[0181] like Figure 10 As shown, in some embodiments, this application provides a button cell battery device 100, including 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 battery device 100 the separator 102 without the insulating adhesive layer 104.

[0182] 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.

[0183] 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 10 (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.

[0184] 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.

[0185] 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.

[0186] In other embodiments, the filler of the button cell device 100 includes nickel foam.

[0187] 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.

[0188] 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.

[0189] like Figure 11 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;

[0190] 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.

[0191] 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.

[0192] 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.

[0193] In some embodiments, the test apparatus 202 includes a non-removable battery device.

[0194] In this embodiment, the testing device 202 can be a non-removable battery device. For example, it can be a non-removable battery device assembled using the coin cell process.

[0195] In the technical solution of this application embodiment, by designing the test device as a non-removable battery device, that is, without disassembling the battery, the adverse effects of disassembly on subsequent test results are reduced, and more accurate test results are obtained.

[0196] In other embodiments, the test device 202 may also be a button battery device as described in any of the above embodiments, which will not be repeated here.

[0197] 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.

[0198] 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.

[0199] Currently, the commonly used EIS test frequency is 300MHz to 100MHz. However, research has found that when the EIS test frequency is less than 1Hz, a large Faraday current will exist during the test, which will have a significant impact on 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, and the EIS test frequency used can be 300MHz to 1Hz. It is understood that in other embodiments, the target cutoff frequency can also be other values ​​such as 1.1Hz or 1.01Hz, 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.

[0200] In practice, the testing device can be tested according to the following testing procedure:

[0201] ① Let it stand still for a period of time, such as 10 seconds;

[0202] ② Constant potential polarization test, test parameters: polarization voltage 10mV vs. Eoc, test duration 10 minutes.

[0203] Collect current and voltage change data during this process;

[0204] ③ EIS test, test parameters: polarization voltage 10mV vs. Eoc, test frequency 300MHz~1Hz

[0205] (i.e., EIS testing is performed under a 10mV polarization state), and the first electrochemical impedance spectroscopy data during this process are collected.

[0206] ④ Let stand for 30 minutes;

[0207] ⑤ EIS test, test parameters: 0mV vs. Eoc, test frequency: 300MHz~1Hz (EIS test is performed in open circuit state), and second electrochemical impedance spectroscopy data are collected.

[0208] ⑥ Let it stand for 30 minutes, then prepare for cross-validation testing;

[0209] ⑦ Constant potential polarization test, test parameters: verification voltage is 15mV vs. Eoc, test duration is 10 minutes (i.e. 15mV polarization for 10 minutes), and current change verification data and voltage change verification data are collected during this process;

[0210] ⑧ EIS test, test parameters: 15mV vs. Eoc, test frequency: 300MHz~1Hz (EIS test is performed under 15mV polarization state), and third electrochemical impedance spectroscopy data are collected.

[0211] In the technical solution of this application embodiment, by setting the target cutoff frequency, both the phase ohmic impedance and interface impedance can be completely tested, and the influence of Faraday current on the test results can be effectively reduced.

[0212] Based on the same inventive concept, this application also provides an electrolyte ion mobility number testing device for implementing the above-described electrolyte ion mobility number testing method. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations in one or more electrolyte ion mobility number testing device embodiments provided below can be found in the limitations of the electrolyte ion mobility number testing method described above, and will not be repeated here.

[0213] In some embodiments, such as Figure 12 As shown, an electrolyte ion transport number testing device is provided, comprising: a data acquisition module 710 and an ion transport number determination module 720, wherein:

[0214] The data acquisition module 710 is used to acquire test data obtained by sequentially performing constant potential polarization test and electrochemical impedance spectroscopy test on the test battery pack at the test voltage. The test data includes voltage change data and current change data of each test battery pack under constant potential polarization state, first electrochemical impedance spectroscopy data under polarization state and second electrochemical impedance spectroscopy data under open circuit state.

[0215] The ion mobility number determination module 720 is used to determine the ion mobility number of each test battery pack based on the voltage change data, the current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data.

[0216] In the technical solution of this application embodiment, by first performing a constant potential polarization test on the test battery pack and then performing an electrochemical impedance spectroscopy test, the possibility of a large instantaneous current in the constant potential polarization test caused by performing an electrochemical impedance spectroscopy test first, which could lead to a deviation in the accuracy of the current test, can be reduced. This allows for the measurement of accurate current change data under conditions without other influencing factors. Furthermore, based on the accurate current change data, voltage change data, first electrochemical impedance spectroscopy data, and second electrochemical impedance spectroscopy data, a more accurate ion transference number can be obtained.

[0217] like Figure 13 As shown, in some embodiments, the device further includes a voltage correction module 712 for correcting the voltage in the voltage change data to obtain the target polarization voltage, and an ion migration number determination module 720 for determining the ion migration number of each test battery pack based on the target polarization voltage, current change data, first electrochemical impedance spectroscopy data and second electrochemical impedance spectroscopy data.

[0218] In some embodiments, the voltage change data includes the open-circuit voltage, and the voltage correction module 712 is further configured to determine the average voltage based on the voltage change data, and obtain the target polarization voltage based on the average voltage and the open-circuit voltage.

[0219] In some embodiments, the current change data includes initial current and steady-state current. The ion migration number determination module 720 is also used to fit the first electrochemical impedance spectroscopy data and the second electrochemical impedance spectroscopy data to obtain the first interface impedance and the second interface impedance, and to determine the ion migration number of each test battery pack based on the target polarization voltage, initial current, steady-state current, first interface impedance and second interface impedance.

[0220] In some embodiments, the current change data includes initial current and steady-state current. The ion transport number determination module 720 is further configured to perform fitting processing on the first electrochemical impedance spectroscopy data to obtain the first interface impedance and the first ohmic impedance, and to perform fitting processing on the second electrochemical impedance spectroscopy data to obtain the second interface impedance and the second ohmic impedance. Based on the target polarization voltage, initial current, steady-state current, first interface impedance, first ohmic impedance, second interface impedance, and second ohmic impedance, the ion transport number of each test battery pack is determined.

[0221] In some embodiments, the current change data includes initial current and steady-state current. The ion transport number determination module 720 is further configured to perform fitting processing on the first electrochemical impedance spectroscopy data to obtain a first interface impedance and a first ohmic impedance, and to perform fitting processing on the second electrochemical impedance spectroscopy data to obtain a second interface impedance and a second ohmic impedance. The first ohmic impedance and the second ohmic impedance are corrected according to a preset correction coefficient to obtain a first target ohmic impedance and a second target ohmic impedance. The ion transport number of each test battery pack is determined based on the target polarization voltage, initial current, steady-state current, first interface impedance, first target ohmic impedance, second interface impedance, and second target ohmic impedance.

[0222] like Figure 13 As shown, in some embodiments, the device further includes an abnormal data screening module 730, which is used to fit the second electrochemical impedance spectroscopy data to obtain the second ohmic impedance, SEI impedance and charge transfer impedance. Based on the target polarization voltage, the second ohmic impedance, SEI impedance, charge transfer impedance and the initial current, the voltage difference is obtained. The voltage difference is compared with a preset voltage difference threshold to screen out abnormal battery groups. Abnormal battery groups are battery groups with voltage differences less than the preset voltage difference threshold. The test data and ion migration number of abnormal battery groups are removed.

[0223] like Figure 13 As shown, in some embodiments, the device further includes a data verification module 740, used to acquire verification data obtained by sequentially performing constant potential polarization tests and electrochemical impedance spectroscopy tests on the test battery packs at a verification voltage. The verification data includes voltage change verification data and current change verification data of each test battery pack under constant potential polarization state, as well as third electrochemical impedance spectroscopy data under polarization state. The voltage in the voltage change verification data is corrected to obtain the target polarization voltage verification value. Based on the polarization verification voltage, current change verification data, third electrochemical impedance spectroscopy data, and second electrochemical impedance spectroscopy data, the ion migration number verification value of each test battery pack is determined. The ion migration number and ion migration number verification value of each test battery pack are compared. Based on the comparison results, the target abnormal battery packs are screened out.

[0224] Each module in the aforementioned 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 the processor of a computer device in hardware form or independent of it, 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.

[0225] In some embodiments, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 14As 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 computing 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 method for testing the transport number of electrolyte ions. The display unit is used to form a visually visible image and can be a display screen, projection device, or 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.

[0226] Those skilled in the art will understand that Figure 14 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.

[0227] 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 electrolyte ion transport number test method.

[0228] 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 electrolyte ion transport number test method.

[0229] 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 electrolyte ion transport number test method.

[0230] It should be noted that the data involved in this application (including but not limited to data used for analysis, data stored, data displayed, etc.) are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with the relevant laws, regulations and standards of the relevant countries and regions.

[0231] Those skilled in the art will understand that all or part of the processes in the methods of 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, and when executed, it can include the processes of the embodiments of the above methods. 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.

[0232] 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 testing the ion transport number of an electrolyte, characterized in that, The method includes: The test data obtained by sequentially performing constant potential polarization test and electrochemical impedance spectroscopy test on the test battery pack with the test voltage includes voltage change data and current change data of the test battery pack under constant potential polarization state, first electrochemical impedance spectroscopy data under polarization state and second electrochemical impedance spectroscopy data under open circuit state. The ion migration number of each test battery pack is determined based on the voltage change data, the current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data.

2. The method according to claim 1, characterized in that, Before determining the ion transport number of each test battery pack based on the voltage change data, the current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data, the method further includes: The voltage in the voltage change data is corrected to obtain the target polarization voltage; The determination of the ion transport number for each test battery pack based on the voltage change data, the current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data includes: The ion migration number of each test battery pack is determined based on the target polarization voltage, the current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data.

3. The method according to claim 2, characterized in that, The voltage change data includes open-circuit voltage; The step of correcting the voltage in the voltage change data to obtain the target polarization voltage includes: Based on the voltage change data, determine the average voltage value; The target polarization voltage is obtained based on the average voltage and the open-circuit voltage.

4. The method according to claim 2, characterized in that, The current change data includes initial current and steady-state current; The determination of the ion transport number for each test battery pack based on the target polarization voltage, the current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data includes: The first electrochemical impedance spectroscopy data and the second electrochemical impedance spectroscopy data are fitted to obtain the first interface impedance and the second interface impedance. The ion migration number of each test battery pack is determined based on the target polarization voltage, the initial current, the steady-state current, the first interface impedance, and the second interface impedance.

5. The method according to claim 2, characterized in that, The current change data includes initial current and steady-state current; The determination of the ion transport number for each test battery pack based on the target polarization voltage, the current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data includes: The first electrochemical impedance spectroscopy data is fitted to obtain the first interface impedance and the first ohmic impedance, and the second electrochemical impedance spectroscopy data is fitted to obtain the second interface impedance and the second ohmic impedance. The ion transference number of each test battery pack is determined based on the target polarization voltage, the initial current, the steady-state current, the first interface impedance, the first ohmic impedance, the second interface impedance, and the second ohmic impedance.

6. The method according to claim 2, characterized in that, The current change data includes initial current and steady-state current; Based on the target polarization voltage, the current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data, the ion transport number of each test battery pack is determined as follows: The first electrochemical impedance spectroscopy data is fitted to obtain the first interface impedance and the first ohmic impedance, and the second electrochemical impedance spectroscopy data is fitted to obtain the second interface impedance and the second ohmic impedance. Based on the preset correction coefficient, the first ohmic impedance and the second ohmic impedance are corrected to obtain the first target ohmic impedance and the second target ohmic impedance. The ion transference number of each test battery pack is determined based on the target polarization voltage, the initial current, the steady-state current, the first interface impedance, the first target ohmic impedance, the second interface impedance, and the second target ohmic impedance.

7. The method according to any one of claims 2 to 6, characterized in that, After determining the ion transport number of each test battery pack based on the target polarization voltage, the current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data, the method further includes: The second electrochemical impedance spectroscopy data were fitted to obtain the second ohmic impedance, SEI impedance, and charge transfer impedance. The voltage difference is obtained based on the target polarization voltage, the second ohmic impedance, the SEI impedance, the charge transfer impedance, and the initial current in the current change data; The voltage difference is compared with a preset voltage difference threshold to filter out abnormal battery packs, which are battery packs with a voltage difference less than the preset voltage difference threshold. The test data and ion migration count of the abnormal battery packs were removed.

8. The method according to claim 7, characterized in that, After removing the test data and ion migration count of the abnormal battery packs, the method further includes: The verification data obtained by performing constant potential polarization test and electrochemical impedance spectroscopy test on the test battery pack in sequence with the verification voltage includes voltage change verification data and current change verification data under constant potential polarization state of each test battery pack, as well as third electrochemical impedance spectroscopy data under polarization state. The voltage in the voltage change verification data is corrected to obtain the target polarization voltage verification value; Based on the target polarization voltage verification value, the current change verification data, the third electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data, determine the ion migration number verification value for each test battery pack. By comparing the ion migration number of each test battery pack with the verified ion migration number value, the target abnormal battery pack is selected based on the comparison results.

9. An electrolyte ion transport number testing system, characterized in that, The system includes interconnected testing devices and testing control devices; The test control device is used to perform ion mobility number testing of the test device using the method described in any one of claims 1-8, and to obtain the ion mobility number of the test device.

10. The system according to claim 9, characterized in that, The testing device includes a non-removable battery assembly.

11. The system according to claim 10, characterized in that, The battery 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 battery device a separator without the insulating adhesive layer covering it.

12. The system according to claim 11, characterized in that, The battery device is filled with nickel foam.

13. The system according to claim 12, characterized in that, The battery device includes a button cell battery device.

14. The system according to any one of claims 9 to 13, 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.

15. An electrolyte ion transport number testing device, characterized in that, The device includes: The data acquisition module is used to acquire test data obtained by sequentially performing constant potential polarization test and electrochemical impedance spectroscopy test on the test battery pack at the test voltage. The test data includes voltage change data and current change data of each test battery pack under constant potential polarization state, first electrochemical impedance spectroscopy data under polarization state and second electrochemical impedance spectroscopy data under open circuit state. The ion mobility number determination module is used to determine the ion mobility number of each test battery pack based on the voltage change data, the current change data, the first electrochemical impedance spectroscopy data, and the second electrochemical impedance spectroscopy data.

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 to 8.

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 to 8.

18. A computer program product, comprising a computer program, 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 to 8.

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