Method, device and equipment for evaluating cycle characteristics of battery negative electrode material and medium

Abstract

The invention relates to the technical field of batteries, in particular to an evaluation method and device for cycle characteristics of a battery negative electrode material, electronic equipment and a medium. The evaluation method for the cycle characteristics of the battery negative electrode material comprises the steps that initial-stage charge and discharge calibration is conducted on a tested battery at a set small multiplying power, detection data in the initial-stage discharge calibration process are obtained, and the detection data comprise voltage data, discharge capacity data and discharge depth data; constructing a BOL differential voltage curve based on the detection data obtained in the initial stage discharge calibration process, and determining the number of lithium removal peaks in the BOL differential voltage curve; and based on the number of lithium removal peaks in the BOL differential voltage curve, evaluating whether the battery negative electrode material is rapidly attenuated in the recycling process. According to the technical scheme disclosed by the invention, the battery negative electrode material with excellent cycle characteristics can be quickly screened, meanwhile, the method has certain universality, the material screening period and the battery cell design and test period can be greatly shortened, and the development progress of a product can be accelerated.

Description

Technical Field

[0001] The present disclosure relates to the field of battery technology, and in particular to a method, device, equipment and medium for evaluating the cycle characteristics of a negative electrode material of a battery. Background Art

[0002] Lithium-ion batteries are widely used in electric vehicles as energy storage systems due to their high energy density, excellent power characteristics, long cycle life and environmental friendliness. However, with the development of lithium-ion battery technology and the increase in user requirements for fast charging, the energy density and cycle life of batteries are particularly important when evaluating the performance of lithium-ion batteries. At present, the negative electrode material of commercial lithium-ion batteries is mainly graphite. The more mature graphite materials have approached their theoretical specific capacity upper limit, with little room for improvement and great difficulty. Silicon-based materials have the characteristics of a high theoretical specific capacity of more than 10 times that of graphite, abundant resource reserves on the earth and environmental friendliness, making them a strong competitor for negative electrode materials of lithium-ion batteries. However, the huge volume expansion of silicon-based negative electrode materials during the charge and discharge cycle causes structural damage to the electrode sheet material and a series of interface problems, resulting in its cycle characteristics being of great concern.

[0003] There are two main methods for evaluating the cycle life of lithium-ion batteries with silicon negative electrode materials: one is to obtain data such as the battery capacity retention rate by performing charge and discharge cycle tests on the battery. This method requires a large number of test resources and has a long test cycle. Short-term cycle data still has certain difficulties in accurately evaluating the actual battery life. The second is to establish a mechanism model by inputting various battery parameters, kinetics, thermodynamics and other parameters, and couple the calculation to predict the life of lithium-ion batteries. This method requires high skills and knowledge reserves of testing equipment and engineers. Therefore, by evaluating the cycle life of lithium-ion batteries with silicon negative electrode materials, screening silicon negative electrode materials with excellent cycle characteristics is a huge and time-consuming task. Therefore, it is particularly important to find a method that can quickly predict the cycle life of batteries in order to screen silicon negative electrode materials with excellent cycle characteristics. Summary of the invention

[0004] In order to solve the above technical problems, the present disclosure provides a method, device, equipment and medium for evaluating the cycle characteristics of battery negative electrode materials, which can simply and quickly screen battery negative electrode materials with excellent cycle characteristics. At the same time, it has a certain universality and can greatly shorten the material screening, battery cell design and testing cycle, which is conducive to accelerating the product development progress.

[0005] In a first aspect, the present disclosure provides a method for evaluating the cycle characteristics of a negative electrode material of a battery, comprising:

[0006] Performing initial stage charge and discharge calibration on the test battery at a set small rate, and acquiring detection data during the initial stage discharge calibration process, wherein the detection data includes voltage data, discharge capacity data, and discharge depth data;

[0007] Constructing a BOL differential voltage curve based on the detection data obtained during the initial stage discharge calibration process, and determining the number of delithiation peaks in the BOL differential voltage curve;

[0008] Based on the number of delithiation peaks in the BOL differential voltage curve, it is evaluated whether the negative electrode material of the battery decays rapidly during the cycle use.

[0009] In some embodiments, the step of evaluating whether the negative electrode material of the battery decays rapidly during cyclic use based on the number of delithiation peaks in the BOL differential voltage curve includes:

[0010] When the number of the delithiation peaks is at least two, it is determined that the negative electrode material of the battery decays rapidly during cyclic use.

[0011] In some embodiments, the step of constructing a BOL differential voltage curve based on the detection data acquired during the initial discharge calibration process includes:

[0012] Performing differential calculations based on the voltage data and the discharge capacity data, respectively, and obtaining a corresponding voltage-capacity differential ratio based on the differential calculation results;

[0013] The BOL differential voltage curve is constructed by taking the discharge depth data as the horizontal coordinate and the corresponding voltage-capacity differential ratio as the vertical coordinate.

[0014] In some embodiments, after evaluating whether the negative electrode material of the battery decays rapidly during the cycle use, the method for evaluating the cycle characteristics of the negative electrode material of the battery further includes:

[0015] Performing a cycle test on the test battery, and performing intermediate stage charge and discharge calibration on the test battery at the set small rate during the cycle test, and obtaining detection data during the intermediate stage discharge calibration process;

[0016] Constructing an XOL differential voltage curve based on the detection data in the intermediate stage discharge calibration process, and determining the number of delithiation peaks in the XOL differential voltage curve;

[0017] Based on the number of delithiation peaks in the XOL differential voltage curve, it is determined whether the negative electrode material of the battery decays rapidly during the cycle use process.

[0018] In some embodiments, determining whether the negative electrode material of the battery decays rapidly during cyclic use based on the number of delithiation peaks in the XOL differential voltage curve includes:

[0019] Comparing the number of delithiation peaks in the XOL differential voltage curve and the number of delithiation peaks in the BOL differential voltage curve to obtain a comparison result;

[0020] Determining whether the negative electrode material of the battery decays rapidly during cyclic use according to the comparison result;

[0021] Among them, when the number of delithiation peaks in the XOL differential voltage curve is less than the number of delithiation peaks in the BOL differential voltage curve, it is determined that the negative electrode material of the battery decays rapidly during the cycle use process.

[0022] In some embodiments, during the cycle test, the test battery is calibrated at the set small rate for intermediate stage charge and discharge, including:

[0023] During the cycle test, the intermediate stage charge and discharge calibration is performed multiple times;

[0024] The constructing of the XOL differential voltage curve based on the detection data in the intermediate stage discharge calibration process includes: constructing the corresponding XOL differential voltage curve based on the detection data in each intermediate stage discharge calibration process.

[0025] In some embodiments, performing the intermediate stage charge and discharge calibration multiple times includes: performing the intermediate stage charge and discharge calibration multiple times according to a set cycle interval.

[0026] In a second aspect, the present disclosure further provides a device for evaluating the cycle characteristics of a battery negative electrode material, comprising:

[0027] An acquisition module is used to perform initial stage charge and discharge calibration on the test battery at a set small rate, and acquire detection data during the initial stage discharge calibration process, wherein the detection data includes voltage data, discharge capacity data and discharge depth data;

[0028] A determination module, used to construct a BOL differential voltage curve based on the detection data obtained during the discharge calibration process in the initial stage, and determine the number of delithiation peaks in the BOL differential voltage curve;

[0029] An evaluation module is used to evaluate whether the negative electrode material of the battery decays rapidly during cyclic use based on the number of delithiation peaks in the BOL differential voltage curve.

[0030] In a third aspect, the present disclosure further provides an electronic device, including:

[0031] A processor and a memory, wherein the processor executes the method for evaluating the cycle characteristics of a battery negative electrode material as described in the first aspect by calling a program or instruction stored in the memory.

[0032] In a fourth aspect, the present disclosure further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a program or instruction, wherein the program or instruction enables a computer to execute the method for evaluating the cycle characteristics of a battery negative electrode material as described in the first aspect.

[0033] Compared with the prior art, the technical solution provided by the embodiments of the present disclosure has the following advantages:

[0034] The evaluation method of the cycle characteristics of the battery negative electrode material provided in the embodiment of the present disclosure is to set a small rate to perform the initial stage charge and discharge calibration on the test battery, and obtain the detection data in the initial stage discharge calibration process, the detection data includes voltage data, discharge capacity data and discharge depth data; based on the detection data obtained in the initial stage discharge calibration process, a BOL differential voltage curve is constructed, and the number of delithiation peaks in the BOL differential voltage curve is determined; based on the number of delithiation peaks in the BOL differential voltage curve, whether the battery negative electrode material decays rapidly during the cycle use process is evaluated. The delithiation performance of the battery negative electrode material to be evaluated in the initial discharge stage is obtained by the number of delithiation peaks in the BOL differential voltage curve, so as to quickly predict the decay trend of the battery negative electrode material in the later cycle use process, so as to achieve rapid screening of battery negative electrode materials with excellent cycle characteristics. Therefore, through the embodiment of the present disclosure, the battery negative electrode material with excellent cycle characteristics can be quickly screened, and it has a certain universality, which can greatly shorten the material screening, battery cell design and testing cycle, and thus help to speed up the product development progress. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0037] Figure 1 A schematic diagram of a flow chart of a method for evaluating the cycle characteristics of a battery negative electrode material provided in an embodiment of the present disclosure;

[0038] Figure 2 A schematic diagram of a BOL differential voltage curve of a test battery provided in an embodiment of the present disclosure;

[0039] Figure 3 A schematic diagram of a BOL differential voltage curve of another test battery provided in an embodiment of the present disclosure;

[0040] Figure 4 A schematic diagram of a differential voltage curve of a test battery provided in an embodiment of the present disclosure;

[0041] Figure 5 A schematic diagram of a differential voltage curve of another test battery provided in an embodiment of the present disclosure;

[0042] Figure 6 A schematic diagram of the structure of a device for evaluating the cycle characteristics of a negative electrode material of a battery provided in an embodiment of the present disclosure;

[0043] Figure 7 A schematic diagram of the structure of an electronic device provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0044] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0045] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0046] The method for evaluating the cycle characteristics of the battery negative electrode material provided in the embodiment of the present disclosure obtains the delithiation performance of the battery negative electrode material to be evaluated in the initial discharge stage by the number of delithiation peaks in the BOL differential voltage curve, thereby quickly predicting the attenuation trend of the battery negative electrode material in the later cycle use process, thereby achieving rapid screening of battery negative electrode materials with excellent cycle characteristics. Through the embodiment of the present disclosure, battery negative electrode materials with excellent cycle characteristics can be quickly screened, and at the same time, it has a certain universality, which can greatly shorten the material screening, battery cell design and testing cycle, and thus help to accelerate the progress of product development.

[0047] In conjunction with the accompanying drawings, the method, device, electronic device and medium for evaluating the cycle characteristics of a negative electrode material of a battery provided by the embodiments of the present disclosure are exemplarily described below.

[0048] Figure 1A flowchart of a method for evaluating the cycle characteristics of a battery negative electrode material provided in an embodiment of the present disclosure. The method is applicable to application scenarios for evaluating the cycle characteristics of a battery negative electrode material. The method can be performed by an evaluation device for the cycle characteristics of a battery negative electrode material provided in an embodiment of the present disclosure, and the evaluation device for the cycle characteristics of a battery negative electrode material can be implemented in software and / or hardware. Figure 1 As shown, the evaluation method of the cycle characteristics of the battery negative electrode material includes the following steps:

[0049] S101, performing initial stage charge and discharge calibration on the test battery at a set small rate, and obtaining detection data during the initial stage discharge calibration process, the detection data including voltage data, discharge capacity data and discharge depth data.

[0050] Specifically, the negative electrode material to be evaluated, such as silicon oxide, is assembled into a full battery, and the full battery is used as a test battery. After the test battery is obtained, the charge and discharge capacity of the test battery is calibrated in a constant temperature box at a set small rate, such as less than or equal to 0.05C, that is, the test battery is calibrated at the initial stage of charge and discharge at a set small rate. During the initial stage charge and discharge calibration of the test battery, the detection data during the discharge calibration process is obtained. Among them, the detection data includes voltage data, discharge capacity data and discharge depth data at different time points. The discharge depth is the ratio of the discharge capacity of the test battery to the rated capacity of the test battery.

[0051] Among them, charging and discharging calibration of the test battery in the initial stage by setting a small rate can reduce the capacity loss of the test battery due to polarization of the test battery during the charge and discharge calibration.

[0052] Exemplarily, the test battery is placed in a constant temperature test device, wherein the test device is connected to an electronic device such as a computer, and the test battery is set to perform charge and discharge calibration at 0.04C through the electronic device to obtain detection data of the test battery during the discharge calibration process.

[0053] S102: constructing a BOL differential voltage curve based on the detection data obtained during the discharge calibration process in the initial stage, and determining the number of delithiation peaks in the BOL differential voltage curve.

[0054] Specifically, based on the voltage data, discharge capacity data, and discharge depth data acquired in S101, a BOL (Beginning of Life, BOL) differential voltage curve of the test battery is constructed by, for example but not limited to, a plotting software. After acquiring the BOL differential voltage curve, the number of delithiation peaks in the BOL differential voltage curve is determined.

[0055] Specifically, the obtained voltage data and discharge capacity data are differentiated, and the differential calculation result of the voltage data is compared with the differential calculation result of the discharge capacity data to obtain a ratio, which is used as the voltage-capacity differential ratio. The discharge depth data is used as the horizontal axis, and the corresponding voltage-capacity differential ratio is used as the vertical axis, so as to construct a BOL differential voltage curve.

[0056] For example, Figure 2 Schematic diagram of a BOL differential voltage curve of a test battery provided by an embodiment of the present disclosure. Figure 2 As shown, the horizontal axis DOD (%) represents the discharge depth, the vertical axis dV / dQ represents the voltage capacity differential ratio, and 1st represents the discharge calibration process in the initial stage of the test battery. Figure 2 Two delithiation peaks 21 appear in the BOL differential voltage curve, namely a first delithiation peak 211 and a second delithiation peak 212 , thereby determining that there are two delithiation peaks in the BOL differential voltage curve.

[0057] For example, Figure 3 FIG. 1 is a schematic diagram of a BOL differential voltage curve of another test battery provided in an embodiment of the present disclosure. Figure 3 As shown, the horizontal axis DOD (%) represents the discharge depth, the vertical axis dV / dQ represents the voltage capacity differential ratio, and 1st represents the discharge calibration process in the initial stage of the test battery. Figure 2 A delithiation peak 21 appears in the BOL differential voltage curve shown.

[0058] In some embodiments, after obtaining the voltage data and the discharge capacity data, the interpolation method can also be used to extract the voltage data and the discharge capacity data at fixed intervals, for example, 500 sets of voltage data and discharge capacity data are extracted. The 500 sets of voltage data and discharge capacity data extracted are differentiated and calculated to obtain the voltage-capacity differential ratio. The discharge depth data is used as the horizontal coordinate, and the corresponding voltage-capacity differential ratio is used as the vertical coordinate to construct the BOL differential voltage curve.

[0059] S103. Based on the number of delithiation peaks in the BOL differential voltage curve, evaluate whether the battery negative electrode material decays rapidly during cyclic use.

[0060] Specifically, in this step, based on the number of delithiation peaks in the acquired BOL differential voltage curve, where the delithiation peak corresponds to the characteristic peak of the negative electrode material such as silicon dioxide, the number of delithiation peaks is used to evaluate the cycle characteristics of the negative electrode material in the test battery during the later use. Exemplarily, the cycle characteristics of the negative electrode material in the test battery during the later use may be manifested as normal attenuation during use, or rapid attenuation, or even cycle diving. When the negative electrode material of the battery decays rapidly during the later use, or even cycles diving, it can be evaluated that the cycle characteristics of the negative electrode material of the battery are poor.

[0061] Therefore, the delithiation performance of the battery negative electrode material to be evaluated in the initial discharge stage can be obtained through the number of delithiation peaks in the BOL differential voltage curve, so as to quickly predict the attenuation trend of the battery negative electrode material in the later cycle use process, thereby achieving rapid screening of battery negative electrode materials with excellent cycle characteristics.

[0062] The evaluation method of the cycle characteristics of the battery negative electrode material provided in the embodiment of the present disclosure performs initial stage charge and discharge calibration on the test battery by setting a small rate, and obtains the detection data in the initial stage discharge calibration process, and the detection data includes voltage data, discharge capacity data and discharge depth data; constructs a BOL differential voltage curve based on the detection data obtained in the initial stage discharge calibration process, and determines the number of delithiation peaks in the BOL differential voltage curve; based on the number of delithiation peaks in the BOL differential voltage curve, evaluates whether the battery negative electrode material decays rapidly during the cycle use process. Through the number of delithiation peaks in the BOL differential voltage curve, the delithiation performance of the battery negative electrode material to be evaluated in the initial discharge stage is obtained, so as to quickly predict the decay trend of the battery negative electrode material in the later cycle use process, so as to achieve rapid screening of battery negative electrode materials with excellent cycle characteristics. Therefore, through the embodiment of the present disclosure, battery negative electrode materials with excellent cycle characteristics can be quickly screened, and at the same time, it has a certain universality, which can greatly shorten the material screening, battery cell design and testing cycle, and thus help to speed up the product development progress.

[0063] In some embodiments, based on the number of delithiation peaks in the BOL differential voltage curve, evaluating whether the negative electrode material of the battery decays rapidly during the cycle use process includes:

[0064] When the number of delithiation peaks is at least two, it is determined that the negative electrode material of the battery decays rapidly during cyclic use.

[0065] Specifically, when the number of delithiation peaks in the BOL differential voltage curve is multiple, it can be determined that the negative electrode material of the battery decays rapidly during the cycle use process, and the cycle characteristics of the negative electrode material of the battery can be evaluated as poor. When the number of delithiation peaks in the BOL differential voltage curve is one, it can be determined that the negative electrode material of the battery decays normally during the cycle use process, and the cycle characteristics of the negative electrode material of the battery can be evaluated as good.

[0066] Therefore, by obtaining the number of delithiation peaks in the BOL differential voltage curve, the battery negative electrode materials with excellent cycle characteristics can be quickly screened. At the same time, it has a certain universality and can greatly shorten the material screening, battery cell design and testing cycle, which is conducive to accelerating the product development progress.

[0067] In some embodiments, after evaluating whether the negative electrode material of the battery decays rapidly during the cycle use, the method for evaluating the cycle characteristics of the negative electrode material of the battery further includes:

[0068] Performing a cycle test on the test battery, and performing intermediate stage charge and discharge calibration on the test battery at a set small rate during the cycle test, and obtaining detection data during the intermediate stage discharge calibration process;

[0069] Constructing an XOL differential voltage curve based on the detection data during the intermediate stage discharge calibration process, and determining the number of delithiation peaks in the XOL differential voltage curve;

[0070] Based on the number of delithiation peaks in the XOL differential voltage curve, it is determined whether the battery negative electrode material decays rapidly during cycling.

[0071] Specifically, in combination with the above, after the test battery is calibrated for the initial stage charge and discharge at a set small rate, the test battery is subjected to a use cycle test, and the test battery is calibrated for the intermediate stage charge and discharge at a set small rate during the use cycle test. Exemplarily, after the test battery has been tested for, for example but not limited to, 500 use cycle cycles, the test battery is calibrated for charge and discharge at a set small rate to obtain the detection data of the test battery during the intermediate stage discharge calibration process. The use cycle test process can be carried out under set cycle conditions, and the set cycle conditions are, for example but not limited to, a temperature of 25±2°C, a voltage window of 2.7-4.25V, and a current setting rate of 1C / 1C.

[0072] After obtaining the test data of the test battery in the intermediate stage discharge calibration process, an XOL (X of Life, XOL) differential voltage curve is constructed based on the test data in the intermediate stage discharge calibration process. The difference between the XOL differential voltage curve and the BOL differential voltage curve is that the BOL differential voltage curve is constructed by the discharge process detection data obtained by the test battery in the initial stage charge and discharge calibration with a set small rate, and the XOL differential voltage curve is constructed by the discharge process detection data obtained by the test battery in the intermediate stage charge and discharge calibration with a set small rate.

[0073] For details on how to construct the XOL differential voltage curve, please refer to the construction process of the BOL differential voltage curve in the above text, which will not be repeated here.

[0074] After obtaining the XOL differential voltage curve, the number of delithiation peaks in the XOL differential voltage curve can be obtained. The number of delithiation peaks in the XOL differential voltage curve can be used to determine whether the negative electrode material of the battery decays rapidly during the cycle. How to determine whether the negative electrode material of the battery decays rapidly during the cycle based on the number of delithiation peaks in the XOL differential voltage curve is described in detail below.

[0075] In some embodiments, determining whether the negative electrode material of the battery decays rapidly during cycling based on the number of delithiation peaks in the XOL differential voltage curve includes:

[0076] The comparison result is obtained by comparing the number of delithiation peaks in the XOL differential voltage curve and the number of delithiation peaks in the BOL differential voltage curve;

[0077] Determine whether the negative electrode material of the battery decays rapidly during the cycle use according to the comparison result;

[0078] Among them, when the number of delithiation peaks in the XOL differential voltage curve is less than the number of delithiation peaks in the BOL differential voltage curve, it is determined that the battery negative electrode material decays rapidly during the cycle use process.

[0079] Specifically, the BOL differential voltage curve is constructed by the discharge process detection data obtained by the test battery at a set small rate for the initial stage charge and discharge calibration, and the XOL differential voltage curve is constructed by the discharge process detection data obtained by the test battery at a set small rate for the intermediate stage charge and discharge calibration. Therefore, for the same battery negative electrode material, the BOL differential voltage curve and the XOL differential voltage curve can be obtained respectively.

[0080] Combined with the previous text, after obtaining the BOL differential voltage curve, the number of delithiation peaks in the BOL differential voltage curve can be used to determine whether the negative electrode material of the battery decays rapidly during the cycle use process. In order to verify the reliability of determining whether the negative electrode material of the battery decays rapidly during the cycle use process based on the BOL differential voltage curve, the XOL differential voltage curve of the test battery is obtained, and the number of delithiation peaks in the XOL differential voltage curve is compared with the number of delithiation peaks in the BOL differential voltage curve. Specifically, when the number of delithiation peaks in the XOL differential voltage curve is less than the number of delithiation peaks in the BOL differential voltage curve, it can be determined that the negative electrode material of the battery decays rapidly during the cycle use process.

[0081] For example, Figure 4 A schematic diagram of a differential voltage curve of a test battery provided in an embodiment of the present disclosure. Figure 4 As shown, the horizontal axis DOD (%) represents the discharge depth, the vertical axis dV / dQ represents the voltage capacity differential ratio, and 1st represents the discharge calibration process of the test battery in the initial stage, corresponding to Figure 2 The BOL differential voltage curve in the figure; 500th represents the discharge calibration process of the test battery in the intermediate test stage and after 500 test cycles, corresponding to the XOL differential voltage curve. Figure 2 and Figure 4 , in the BOL differential voltage curve, two delithiation peaks 21 appear, at this time it can be determined that the negative electrode material of the battery decays rapidly during the cycle use. In order to verify the reliability of the above determination result, the XOL differential voltage curve is obtained, and a delithiation peak 21 appears in the XOL differential voltage curve. It can be obtained that the two delithiation peaks in the BOL differential voltage curve are merged into one delithiation peak in the XOL differential voltage curve. It can be determined that as the test battery is cycled, the negative electrode material of the test battery, such as silicon oxide, undergoes significant changes in structure, and the change in the negative electrode material itself will cause the battery capacity to decay rapidly. Therefore, when the number of delithiation peaks in the XOL differential voltage curve is less than the number of delithiation peaks in the BOL differential voltage curve, it can be determined that the negative electrode material of the battery decays rapidly during the cycle use.

[0082] For example, Figure 5 This is a schematic diagram of a differential voltage curve of another test battery provided by an embodiment of the present disclosure. Figure 5 As shown, the horizontal axis DOD (%) represents the discharge depth, the vertical axis dV / dQ represents the voltage capacity differential ratio, and 1st represents the discharge calibration process of the test battery in the initial stage, corresponding to Figure 3 The BOL differential voltage curve in the figure; 500th represents the discharge calibration process of the test battery in the intermediate test stage and after 500 test cycles, corresponding to the XOL differential voltage curve. Figure 3 and Figure 5, in the BOL differential voltage curve, a delithiation peak 21 appears, at this time it can be determined that the negative electrode material of the battery decays normally during the cyclic use. In order to verify the reliability of the above determination result, the XOL differential voltage curve is obtained, and a delithiation peak 21 appears in the XOL differential voltage curve. Compared with a delithiation peak in the XOL differential voltage curve and a delithiation peak in the BOL differential voltage curve, the delithiation peak only has a shift in the peak position, and there is no change in the peak shape or the merging and disappearance of the peaks. It can be determined that as the test cycle of the test battery proceeds, the intrinsic structural characteristics of the negative electrode material of the test battery, such as silicon dioxide material, have not changed significantly, and the negative electrode material of the test battery decays normally. Therefore, in the XOL differential voltage curve and the BOL differential voltage curve, the delithiation peak only has a shift in the peak position, which can determine that the negative electrode material of the battery decays normally during the cyclic use.

[0083] Therefore, after obtaining the BOL differential voltage curve, the XOL differential voltage curve is obtained, and the number of delithiation peaks in the XOL differential voltage curve and the number of delithiation peaks in the BOL differential voltage curve are compared to verify whether the cycle characteristics of the battery negative electrode material during use evaluated by the BOL differential curve are reliable. By comparing the results, it is determined that the above evaluation results are reliable. Therefore, by obtaining the delithiation performance of the negative electrode material to be evaluated in the initial stage of the test battery, the attenuation trend of the material in the later stage of the cycle can be quickly predicted, so as to screen materials with excellent cycle characteristics, so as to achieve the purpose of rapid screening of materials.

[0084] In some embodiments, during the cycle test, the test battery is calibrated at an intermediate stage of charge and discharge at a set small rate, including:

[0085] During the cycle test, multiple intermediate charge and discharge calibrations are performed;

[0086] Constructing an XOL differential voltage curve based on detection data in the intermediate stage discharge calibration process includes: constructing a corresponding XOL differential voltage curve based on detection data in each intermediate stage discharge calibration process.

[0087] Specifically, during the test battery cycle test, multiple intermediate stage charge and discharge calibrations are performed, and multiple intermediate stage charge and discharge calibrations can be performed according to set cycle intervals. For example, an intermediate stage charge and discharge calibration is obtained every 100 cycles, thereby obtaining multiple XOL differential voltage curves.

[0088] Exemplarily, after the test battery has been cycled 100 times, an intermediate stage charge and discharge calibration is performed, and the first XOL differential voltage curve is constructed based on the detection data in the discharge calibration process; after the test battery has been cycled 200 times, an intermediate stage charge and discharge calibration is performed, and the second XOL differential voltage curve is constructed based on the detection data in the discharge calibration process; after the test battery has been cycled 300 times, a third intermediate stage charge and discharge calibration is performed, and the third XOL differential voltage curve is constructed based on the detection data in the discharge calibration process; after the test battery has been cycled 400 times, a fourth intermediate stage charge and discharge calibration is performed, and the fourth XOL differential voltage curve is constructed based on the detection data in the discharge calibration process; after the test battery has been cycled 500 times, a fifth intermediate stage charge and discharge calibration is performed, and the fifth XOL differential voltage curve is constructed based on the detection data in the discharge calibration process. In this way, multiple XOL differential voltage curves can be obtained.

[0089] For the multiple XOL differential voltage curves obtained above, when two delithiation peaks appear in the BOL differential voltage curve of the test battery, as the test battery is cycled, it can be obtained that not only the position of the delithiation peak in the XOL differential voltage curve is shifted, but also the two delithiation peaks gradually merge into one delithiation peak. For the multiple XOL differential voltage curves obtained above, when one delithiation peak appears in the BOL differential voltage curve of the test battery, as the test battery is cycled, it can be obtained that one delithiation peak in the XOL differential voltage curve only shifts in position.

[0090] Based on the same inventive concept, an embodiment of the present disclosure also provides a device for evaluating the cycle characteristics of a battery negative electrode material. Figure 6 A schematic diagram of a battery negative electrode material cycle performance evaluation device provided in an embodiment of the present disclosure. Figure 6 As shown, the evaluation device for the cycle characteristics of the battery negative electrode material includes: an acquisition module 61, which is used to perform initial stage charge and discharge calibration on the test battery at a set small rate, and obtain detection data during the initial stage discharge calibration process, the detection data including voltage data, discharge capacity data and discharge depth data; a determination module 62, which is used to construct a BOL differential voltage curve based on the detection data obtained during the initial stage discharge calibration process, and determine the number of delithiation peaks in the BOL differential voltage curve; an evaluation module 63, which is used to evaluate whether the battery negative electrode material decays rapidly during cyclic use based on the number of delithiation peaks in the BOL differential voltage curve.

[0091] The battery negative electrode material cycle characteristics evaluation device provided in the above embodiments can execute any of the battery negative electrode material cycle characteristics evaluation methods provided in the above embodiments, and has the same or corresponding beneficial effects, which will not be described one by one here.

[0092] The embodiments of the present disclosure also provide a computer storage medium, which stores programs or instructions, and the programs or instructions enable a computer to execute the steps of any of the methods for evaluating the cycle characteristics of battery negative electrode materials provided in the above embodiments.

[0093] Exemplarily, the program or instruction enables a computer to execute a method for evaluating the cycle characteristics of a negative electrode material of a battery, the method for evaluating the cycle characteristics of a negative electrode material of a battery comprising:

[0094] Performing initial stage charge and discharge calibration on the test battery at a set small rate, and obtaining detection data during the initial stage discharge calibration process, the detection data including voltage data, discharge capacity data and discharge depth data;

[0095] Constructing a BOL differential voltage curve based on the detection data obtained during the initial stage discharge calibration process, and determining the number of delithiation peaks in the BOL differential voltage curve;

[0096] Based on the number of delithiation peaks in the BOL differential voltage curve, it is evaluated whether the battery negative electrode material decays rapidly during cycling.

[0097] In some embodiments, the computer executable instructions, when executed by a computer processor, can also be used to execute any of the above-mentioned technical solutions for evaluating the cycle characteristics of battery negative electrode materials provided in the embodiments of the present disclosure, to achieve corresponding beneficial effects.

[0098] Through the above description of the implementation mode, the technicians in the relevant field can clearly understand that the present disclosure can be implemented by means of software and necessary general hardware, and of course it can also be implemented by hardware, but in many cases the former is a better implementation mode. Based on such an understanding, the technical solution of the present disclosure is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, a read-only memory (ROM), a random access memory (RAM), a flash memory (FLASH), a hard disk or an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform the evaluation method of the cycle characteristics of the battery negative electrode material in each embodiment of the present invention.

[0099] Based on the above implementation, the embodiment of the present disclosure further provides an electronic device. Figure 7 The structure diagram of an electronic device provided by the embodiment of the present disclosure is shown in FIG. Figure 7As shown, the electronic device includes: a processor and a memory; the processor calls the program or instructions stored in the memory to execute the steps of any one of the battery negative electrode material cycle characteristics evaluation methods provided in the above embodiments to achieve corresponding beneficial effects.

[0100] Figure 7 Schematic diagram of the hardware structure of the electronic device provided by the embodiment of the present disclosure. Figure 7 As shown, the electronic device includes one or more processors 501 and a memory 502. The processor 501 may be a central processing unit (CPU) or other processing units having data processing capability and / or instruction execution capability, and may control other components in the electronic device to perform desired functions.

[0101] The memory 502 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, a random access memory (RAM) and / or a cache memory (cache), etc. The non-volatile memory may include, for example, a read-only memory (ROM), a hard disk, a flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 501 may run the program instructions to implement the method of the embodiment of the present disclosure described above, and / or other desired functions. Various contents such as input signals, signal components, noise components, etc. may also be stored in the computer-readable storage medium.

[0102] In one example, the electronic device may further include: an input device 503 and an output device 504, and these components are interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0103] In addition, the input device 503 may also include, for example, a keyboard, a mouse, and the like.

[0104] The output device 504 can output various information to the outside, including the determined distance information, direction information, etc. The output device 504 can include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto, and the like.

[0105] Of course, to simplify, Figure 7 Only some of the components related to the present disclosure in the electronic device are shown, and components such as a bus, an input / output interface, etc. are omitted. In addition, according to specific application situations, the electronic device may further include any other appropriate components.

[0106] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0107] The above description is only a specific embodiment of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for evaluating the cycle characteristics of a battery negative electrode material, characterized in that: include: Performing initial stage charge and discharge calibration on the test battery at a set small rate, and acquiring detection data during the initial stage discharge calibration process, wherein the detection data includes voltage data, discharge capacity data, and discharge depth data; Constructing a BOL differential voltage curve based on the detection data obtained during the initial stage discharge calibration process, and determining the number of delithiation peaks in the BOL differential voltage curve; Based on the number of delithiation peaks in the BOL differential voltage curve, it is evaluated whether the negative electrode material of the battery decays rapidly during the cycle use.

2. The method for evaluating the cycle characteristics of a negative electrode material of a battery according to claim 1, characterized in that: The method of evaluating whether the negative electrode material of the battery decays rapidly during the cycle use based on the number of delithiation peaks in the BOL differential voltage curve includes: When the number of the delithiation peaks is at least two, it is determined that the negative electrode material of the battery decays rapidly during cyclic use.

3. The method for evaluating the cycle characteristics of a negative electrode material of a battery according to claim 1, characterized in that: The method of constructing a BOL differential voltage curve based on the detection data obtained during the discharge calibration process in the initial stage includes: Performing differential calculations based on the voltage data and the discharge capacity data, respectively, and obtaining a corresponding voltage-capacity differential ratio based on the differential calculation results; The BOL differential voltage curve is constructed by taking the discharge depth data as the horizontal coordinate and the corresponding voltage-capacity differential ratio as the vertical coordinate.

4. The method for evaluating the cycle characteristics of a negative electrode material of a battery according to any one of claims 1 to 3, characterized in that: After evaluating whether the negative electrode material of the battery decays rapidly during the cycle use, it also includes: Performing a cycle test on the test battery, and performing intermediate stage charge and discharge calibration on the test battery at the set small rate during the cycle test, and obtaining detection data during the intermediate stage discharge calibration process; Constructing an XOL differential voltage curve based on the detection data in the intermediate stage discharge calibration process, and determining the number of delithiation peaks in the XOL differential voltage curve; Based on the number of delithiation peaks in the XOL differential voltage curve, it is determined whether the negative electrode material of the battery decays rapidly during the cycle use process.

5. The method for evaluating the cycle characteristics of a negative electrode material of a battery according to claim 4, characterized in that: The method of determining whether the negative electrode material of the battery decays rapidly during the cycle use based on the number of delithiation peaks in the XOL differential voltage curve includes: Comparing the number of delithiation peaks in the XOL differential voltage curve and the number of delithiation peaks in the BOL differential voltage curve to obtain a comparison result; Determining whether the negative electrode material of the battery decays rapidly during cyclic use according to the comparison result; Wherein, when the number of delithiation peaks in the XOL differential voltage curve is less than the number of delithiation peaks in the BOL differential voltage curve, it is determined that the negative electrode material of the battery decays rapidly during the cycle use process.

6. The method for evaluating the cycle characteristics of a negative electrode material of a battery according to claim 4, characterized in that: During the cycle test, the test battery is calibrated at the intermediate stage of charge and discharge at the set small rate, including: During the cycle test, the intermediate stage charge and discharge calibration is performed multiple times; The constructing of the XOL differential voltage curve based on the detection data in the intermediate stage discharge calibration process includes: constructing the corresponding XOL differential voltage curve based on the detection data in each intermediate stage discharge calibration process.

7. The method for evaluating the cycle characteristics of a negative electrode material of a battery according to claim 6, characterized in that: The performing of the intermediate stage charge and discharge calibration multiple times includes: performing the intermediate stage charge and discharge calibration multiple times according to a set cycle interval.

8. A device for evaluating the cycle characteristics of a battery negative electrode material, characterized in that: include: An acquisition module is used to perform initial stage charge and discharge calibration on the test battery at a set small rate, and acquire detection data during the initial stage discharge calibration process, wherein the detection data includes voltage data, discharge capacity data and discharge depth data; A determination module, used to construct a BOL differential voltage curve based on the detection data obtained during the discharge calibration process in the initial stage, and determine the number of delithiation peaks in the BOL differential voltage curve; The evaluation module is used to evaluate whether the negative electrode material of the battery decays rapidly during the cycle use based on the number of delithiation peaks in the BOL differential voltage curve.

9. An electronic device, characterized in that: include: A processor and a memory, wherein the processor executes the method for evaluating the cycle characteristics of a battery negative electrode material as described in any one of claims 1 to 7 by calling a program or instruction stored in the memory.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a program or instruction, and the program or instruction enables a computer to execute the method for evaluating the cycle characteristics of a negative electrode material for a battery according to any one of claims 1 to 7.

Images