Electrode material performance evaluation method, device and system and storage medium

Abstract

The invention provides an electrode material performance evaluation method, device and system and a storage medium. The method comprises the following steps: acquiring a target charge-discharge voltage range of a battery made of a to-be-tested electrode material; wherein the width of the target charge-discharge voltage range is greater than the width of the standard charge-discharge voltage range of the battery; circularly charging and discharging the battery in the target charging and discharging voltage range, and acquiring charging and discharging data of the battery in the circular charging and discharging process; and evaluating the cycle performance of the to-be-tested electrode material based on the charging and discharging data. According to the scheme, the lithium consumption of the battery made of the to-be-tested electrode material is increased by widening the charge-discharge voltage range, so that the cycle performance of the to-be-tested electrode material can be evaluated based on the charge-discharge data in the few cycle charge-discharge processes, the test period is effectively shortened, and the test efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to an electrode material performance evaluation method, device, system and storage medium. BACKGROUND

[0002] With the rapid development of the new energy industry, the market's demand for lithium battery life performance continues to increase, prompting the continuous increase in research and development investment in electrode materials (such as positive electrode materials) at the material level, and the acceleration of the iteration speed of new powders.

[0003] Electrode material cycle performance testing usually requires full-cycle cycle testing to verify the life (the test period is usually more than 3 months), and the long test period results in a large amount of research and development powders being unable to complete life detection in a timely manner, slowing down the progress of material formula optimization. Therefore, there is an urgent need for a life performance testing method that can shorten the test period to match the research and development pace and improve detection efficiency. SUMMARY

[0004] The present application provides an electrode material performance evaluation method, device, system and storage medium, which can effectively shorten the test period and improve the test efficiency.

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides an electrode material performance evaluation method, which comprises: obtaining a target charge-discharge voltage range of a battery made of a to-be-tested electrode material; wherein the width of the target charge-discharge voltage range is greater than the width of a standard charge-discharge voltage range of the battery; performing cycle charge-discharge on the battery in the target charge-discharge voltage range and obtaining charge-discharge data of the battery in the cycle charge-discharge process; wherein the charge-discharge data includes discharge capacity; and evaluating the cycle performance of the to-be-tested electrode material based on the charge-discharge data.

[0006] In the scheme provided in the present application, the charge-discharge voltage range is widened to increase the lithium consumption of the battery of the to-be-tested electrode material, so that the cycle performance evaluation of the to-be-tested electrode material can be performed according to the charge-discharge data in a fewer number of cycle charge-discharge processes, the test period is effectively shortened, and the test efficiency is improved.

[0007] In some optional embodiments, the method further includes: performing charging and discharging on the sample battery according to a preset charging and discharging voltage range, wherein a width of the preset charging and discharging voltage range is greater than a width of the standard charging and discharging voltage range; obtaining battery charging data and battery discharging data of the sample battery during the charging and discharging, to obtain a battery charging data set and a battery discharging data set respectively; determining the end phase change voltage according to the battery charging data set, and determining the target start phase change voltage according to the battery discharging data set; wherein the target start phase change voltage is less than a lower limit voltage of the standard charging and discharging voltage range; and determining the target charging and discharging voltage range of the battery made of the electrode material to be tested according to the end phase change voltage and the target start phase change voltage.

[0008] In the scheme provided in the application, the charging and discharging data set of the sample battery is used to determine phase change information, and the boundary of the target charging and discharging voltage range is determined based on the target phase change voltage. The determination method can quickly locate the voltage point that can increase the lithium consumption of the electrode material, and can provide a standard determination method for widening the voltage range boundary of different electrode materials, so that the cycle performance of different electrode materials can be accelerated to be exhibited.

[0009] In some optional embodiments, the performing charging and discharging on the sample battery according to a preset charging and discharging voltage range includes: charging the sample battery to a first preset charging cutoff voltage according to a preset charging rate, wherein the first preset charging cutoff voltage is greater than an upper limit voltage of the standard charging and discharging voltage range; and discharging the sample battery to a second preset discharging cutoff voltage according to a preset discharging rate, wherein the second preset discharging cutoff voltage is less than the lower limit voltage of the standard charging and discharging voltage range.

[0010] In the scheme provided in the application, the upper and lower limit voltages of the charging and discharging voltage range are simultaneously widened, so that overcharging and overdischarging are performed in the charging and discharging processes respectively, the lithium consumption of the battery is accelerated, and the cycle performance of the electrode material to be tested is quickly characterized, thereby improving the detection efficiency.

[0011] In some optional embodiments, the determining the end phase change voltage according to the battery charging data set and the determining the target start phase change voltage according to the battery discharging data set include: determining a first differential capacity curve according to the battery charging voltage and the battery charging capacity in the battery charging data set; determining a second differential capacity curve according to the battery discharging voltage and the battery discharging capacity in the battery discharging data set; obtaining a first battery voltage corresponding to a terminal phase state peak in the first differential capacity curve, and obtaining a second battery voltage corresponding to a target start phase state peak in the second differential capacity curve, to obtain the end phase change voltage and the target start phase change voltage respectively.

[0012] In the scheme provided in the application, by determining the charging differential capacity curve and the discharging differential capacity curve according to the battery charging data set and the battery discharging data set, the phase change information of the battery in the charging and discharging process can be obtained according to the characteristic peaks in the curves, so that the target phase change voltage can be quickly and accurately determined.

[0013] In some optional embodiments, the target charging and discharging voltage range of the battery made of the electrode material to be tested is determined according to the termination phase change voltage and the target starting phase change voltage, comprising: obtaining the sum of the termination phase change voltage and a first preset threshold to obtain a target termination phase change voltage; obtaining the difference between the target starting phase change voltage and a second preset threshold to obtain a first target starting phase change voltage; taking the target termination phase change voltage as a minimum charging upper limit voltage; taking the first target starting phase change voltage as a maximum discharging lower limit voltage; and determining the target charging and discharging voltage range of the battery made of the electrode material to be tested based on the minimum charging upper limit voltage and the maximum discharging lower limit voltage.

[0014] In the scheme provided in the application, by adjusting the obtained termination phase change voltage and target starting phase change voltage, the boundaries of the target charging and discharging voltage range can be further widened, and the cycle performance characterization can be accelerated.

[0015] In some optional embodiments, the target charging and discharging voltage range of the battery made of the electrode material to be tested is determined based on the minimum charging upper limit voltage and the maximum discharging lower limit voltage, comprising: obtaining the corrosion critical voltage of the current collector corresponding to the battery; taking the corrosion critical voltage of the current collector as a maximum charging upper limit voltage; and determining the target charging and discharging voltage range of the battery made of the electrode material to be tested based on the minimum charging upper limit voltage, the maximum charging upper limit voltage and the maximum discharging lower limit voltage.

[0016] In the scheme provided in the application, by obtaining the corrosion critical voltage of the current collector in the battery and taking the corrosion critical voltage as the maximum charging upper limit voltage, the corrosion of the current collector caused by the excessive charging upper limit voltage can affect the accuracy of the cycle performance test.

[0017] In some optional embodiments, the battery is cycled and charged and discharged in the target charging and discharging voltage range, comprising: sequentially charging the battery to the upper limit voltage of the target charging and discharging voltage range and discharging the battery to the lower limit voltage of the target charging and discharging voltage range according to a preset cycle number and a preset charging and discharging strategy; and wherein the battery charging event and the battery discharging event are separated by a preset time length.

[0018] In the scheme provided in the application, the battery prepared by the to-be-tested material is subjected to cycle charging and discharging processing by adopting the preset charging and discharging strategy, different actual charging and discharging scenes can be matched, the credibility of the test can be improved, the target charging and discharging voltage range adopted is greater than the standard charging and discharging voltage range of the battery, the battery can be accelerated to consume, the cycle number adopted can be much smaller than the cycle number of the standard test, the cycle test period can be reduced, and the detection efficiency can be effectively improved.

[0019] In some optional embodiments, the charging strategy in the preset charging and discharging strategy comprises: charging the battery at a first preset charging rate to an upper limit voltage of the target charging and discharging voltage range; if it is detected that the voltage of the battery reaches the upper limit voltage, charging the battery at a second preset charging rate to the upper limit voltage; wherein the second preset charging rate is less than the first preset charging rate; or, if it is detected that the voltage of the battery reaches the upper limit voltage, charging the battery at the upper limit voltage to a second preset charging rate of the current of the battery by constant voltage charging; wherein the second preset charging rate is less than the first preset charging rate.

[0020] In the scheme provided in the application, the two-stage constant current charging mode is adopted, after the first stage charging is completed, the second charging rate lower than the first charging rate of the first stage is switched to continue constant current charging or the constant voltage charging mode is adopted, so that the battery can be fully charged.

[0021] In some optional embodiments, the discharging strategy in the preset charging and discharging strategy comprises: discharging the battery at a first preset charging rate to a lower limit voltage of the charging and discharging voltage range; if it is detected that the voltage of the battery reaches the lower limit voltage, discharging the battery at a second preset charging rate to the lower limit voltage; wherein the second preset charging rate is less than the first preset charging rate; or, if it is detected that the voltage of the battery reaches the lower limit voltage, discharging the battery at the lower limit voltage to a second preset charging rate of the current of the battery by constant voltage discharging; wherein the second preset charging rate is less than the first preset charging rate.

[0022] In the scheme provided in the application, the two-stage constant current discharging mode is adopted, after the first stage discharging is completed, the second discharging rate lower than the first discharging rate of the first stage is switched to continue constant current discharging or the constant voltage discharging mode is adopted, so that the battery can be fully discharged.

[0023] In some optional embodiments, the evaluating the cycle performance of the electrode material under test based on the charge-discharge data comprises: obtaining the discharge capacity corresponding to a plurality of target cycle times; determining the capacity retention rate corresponding to the target cycle times according to the discharge capacity; and evaluating the cycle performance of the electrode material under test based on all the capacity retention rates.

[0024] In the scheme provided in the present application, the capacity retention rate is calculated by obtaining the discharge capacity of a plurality of target cycle times, which can intuitively and quantitatively evaluate the result based on the capacity retention rate, making the evaluation process more simple and facilitating the improvement of detection efficiency.

[0025] In some optional embodiments, the battery is a half battery.

[0026] In the scheme provided in the present application, the mass of the electrode material under test can be reduced from kilogram level to gram level by using a half battery as the test object, which reduces the production cycle, effectively improves the detection efficiency, and saves material resources.

[0027] In some optional embodiments, the process of manufacturing the battery from the electrode material under test comprises: manufacturing the electrode material under test into electrode slurry; coating the electrode slurry onto a current collector to manufacture a pole piece; and assembling the pole piece cut to a preset size to manufacture the battery.

[0028] In the scheme provided in the present application, the electrode material under test is prepared into a battery to facilitate the evaluation of the cycle performance of the electrode material under test.

[0029] The second aspect of the present application provides an electrode material performance evaluation device, comprising: an obtaining module configured to obtain a target charge-discharge voltage range of a battery manufactured from an electrode material under test; wherein the width of the target charge-discharge voltage range is greater than the width of a standard charge-discharge voltage range of the battery; a charge-discharge module configured to perform cyclic charge-discharge on the battery within the target charge-discharge voltage range and obtain charge-discharge data of the battery in the cyclic charge-discharge process; wherein the charge-discharge data comprises discharge capacity; and an evaluation module configured to evaluate the cycle performance of the electrode material under test based on the charge-discharge data.

[0030] The third aspect of the present application provides an electrode material performance evaluation system, comprising: a memory and a processor, wherein the processor is configured to execute a computer program stored in the memory, and the processor, when executing the computer program, implements the electrode material performance evaluation method provided in the first aspect of the present application.

[0031] The fourth aspect of the present application provides a computer readable storage medium having a computer program stored thereon, and the computer program, when executed by a processor, implements the electrode material performance evaluation method provided in the first aspect of the present application.

[0032] It can be understood that the beneficial effects of the above-mentioned second aspect to the fourth aspect can be referred to the related description in the first aspect, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0034] Figure 1 A flowchart of an electrode material performance evaluation method provided by some embodiments of the present application is shown in the figure. Figure 2 A battery charging curve provided by some embodiments of the present application is shown in the figure. Figure 3 A flowchart of another electrode material performance evaluation method provided by some embodiments of the present application is shown in the figure. Figure 4 A flowchart of another electrode material performance evaluation method provided by some embodiments of the present application is shown in the figure. Figure 5 A first differential capacity curve provided by some embodiments of the present application is shown in the figure. Figure 6 A second differential capacity curve provided by some embodiments of the present application is shown in the figure. Figure 7 A capacity retention rate curve provided by some embodiments of the present application is shown in the figure. Figure 8 A detailed flowchart of an electrode material performance evaluation method provided by some embodiments of the present application is shown in the figure. Figure 9 A module diagram of an electrode material performance evaluation device provided by some embodiments of the present application is shown in the figure. Figure 10 A structure diagram of an electrode material performance evaluation system provided by some embodiments of the present application is shown in the figure. Figure 11 A structure diagram of a computer readable storage medium for storing or carrying program code for implementing the electrode material performance evaluation method provided by the embodiments of the present application is shown in the figure. DETAILED DESCRIPTION

[0035] In order to make the objectives, characteristics, advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0036] The following description refers to the accompanying drawings. Unless otherwise indicated, same numbers in different drawings indicate same or similar elements. The following description of the example embodiments is not representative of all possible embodiments consistent with the present application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the present application as detailed in the appended claims.

[0037] It should be understood that the term "comprising" as used in the specification and in the claims indicates the presence of the recited features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0038] It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used in this specification and the appended claims, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0039] It should further be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items, and that the term "at least one of" followed by a list of two or more items means any single one of the items in the list individually, as well as any combination of two or more of the items in the list.

[0040] In addition, in the description of the present application, the terms "first", "second", etc. are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features.

[0041] In the development of electrode materials, in order to evaluate the cycle performance of a new type of electrode material, the material needs to be made into a battery and then tested for 1000 to 2000 cycles to verify its capacity retention rate. According to the conventional 0.5C charging and discharging rate (about 2 to 3 hours per cycle), the single life detection needs to last for 100 to 150 days (about 3 to 5 months), and if the material formula needs to be optimized, multiple detections need to be repeated, resulting in a development cycle of 1 to 2 years, which seriously lags behind the market demand for high-performance materials.

[0042] To solve the above problems, the electrode material performance evaluation method, device, system and storage medium provided by the embodiments of the present application are provided. The target charge-discharge voltage range of the battery made of the electrode material to be tested is obtained. The width of the target charge-discharge voltage range is greater than the width of the standard charge-discharge voltage range of the battery. The battery is subjected to cyclic charge-discharge according to the target charge-discharge voltage range. The charge-discharge data of the battery in the cyclic charge-discharge process is obtained. The cycle performance of the electrode material to be tested is evaluated according to the charge-discharge data. By widening the charge-discharge voltage range, the lithium consumption of the battery of the electrode material to be tested is increased. Therefore, the cycle performance of the electrode material to be tested can be evaluated according to the charge-discharge data in a few cycles of charge-discharge process. The test period is effectively shortened, and the test efficiency is improved.

[0043] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. It should be noted that the description order of the following embodiments is not limited as the preferred order of the embodiments.

[0044] Please refer to Figure 1 , Figure 1 The flowchart of the electrode material performance evaluation method provided by some embodiments of the present application is shown. In specific embodiments, the specific process of the electrode material performance evaluation method is as follows: S101, obtaining the target charge-discharge voltage range of the battery made of the electrode material to be tested.

[0045] In the embodiment, the electrode material to be tested can be a positive electrode material (such as ternary material NCM, NCA). The width of the charge-discharge voltage range of the battery corresponding to the electrode material to be tested is greater than the width of the standard charge-discharge voltage range of the battery. The charge-discharge voltage range refers to the interval of the highest charge voltage (upper limit voltage) and the lowest discharge voltage (lower limit voltage) allowed in the normal charge-discharge cycle of the battery. The width of the charge-discharge voltage range refers to the difference between the maximum value and the minimum value of the voltage range.

[0046] The standard charge-discharge voltage range can adopt the platform voltage range of the battery, for example Figure 2The shown charge curve, the horizontal coordinate represents the lithium amount of unit mass active material, and the vertical coordinate represents the battery terminal voltage. As can be seen from the figure, as the capacity increases (the amount of lithium ions increases), the voltage first rises rapidly, and then changes slowly. The slowly changing curve segment is the platform voltage range. The voltage interval containing the platform voltage range can be selected as the charge and discharge voltage range, for example, 3 to 4.2V is selected as the charge and discharge voltage range. In this voltage range, the electrode material performance is relatively stable, and the lithium loss is small, which is better in use, but in order to realize the front-end rapid detection, it is necessary to increase the lithium consumption as much as possible. Lithium consumption refers to the phenomenon that active lithium ions are consumed and cannot participate in normal electrochemical reactions due to participating in irreversible reactions during the charge and discharge cycle of lithium battery. These consumed lithium ions will permanently leave the charge and discharge cycle, directly leading to battery capacity attenuation and performance degradation. Therefore, the boundaries of the standard charge and discharge voltage range are widened, for example, the upper limit voltage is increased, and / or the lower limit voltage is reduced, to increase the lithium consumption and quickly distinguish the stability of the material. Moreover, by expanding the voltage range, only the charge and discharge cutoff voltage needs to be controlled, and the operation is simple.

[0047] S102, performing cycle charge and discharge on the battery in the target charge and discharge voltage range, and obtaining the charge and discharge data of the battery in the cycle charge and discharge process.

[0048] In this embodiment, the battery is charged and discharged multiple times based on the target charge and discharge voltage range, and the battery charge and discharge data in each cycle process or the battery charge and discharge data in the nth cycle process is obtained. The battery charge and discharge data can be battery voltage, battery current, battery capacity, etc.

[0049] S103, evaluating the cycle performance of the measured electrode material based on the charge and discharge data.

[0050] In this embodiment, by analyzing the collected charge and discharge data in the cycle process, the stability of the cycle performance of the measured electrode material can be analyzed. The charge and discharge data can be charge capacity, discharge capacity, etc. Moreover, since the target charge and discharge voltage range that breaks through the standard charge and discharge voltage interval is used, the change range of the charge and discharge data can be accelerated. For example, according to the conventional charge and discharge voltage range, 100 cycles may be needed to obtain the target charge and discharge data (for example, the capacity is 500mAh), while in this embodiment, only 10 cycles are needed to obtain the target charge and discharge data, so that the cycle performance of the measured electrode material can be quickly evaluated, the test period is shortened, and the test efficiency is effectively improved.

[0051] Based on the technical solution of the embodiment of the application, the target charge-discharge voltage range of the battery made of the electrode material to be tested is obtained; the width of the target charge-discharge voltage range is greater than the width of the standard charge-discharge voltage range of the battery; the battery is subjected to cyclic charge-discharge in the target charge-discharge voltage range, and the charge-discharge data of the battery in the cyclic charge-discharge process is obtained; and the cycle performance of the electrode material to be tested is evaluated based on the charge-discharge data. The application widens the charge-discharge voltage range to increase the lithium consumption of the battery made of the electrode material to be tested, so that the cycle performance of the electrode material to be tested can be evaluated based on the charge-discharge data in the cyclic charge-discharge process for fewer times, the test period is effectively shortened, and the test efficiency is improved.

[0052] In the embodiment of the application, there are various strategies for obtaining the target charge-discharge voltage range of the battery made of the electrode material to be tested. Please refer to Figure 3 , Figure 3 The flowchart of another electrode material performance evaluation method provided in the embodiment of the application is as follows: Figure 3 S1011 to S1014 in the above embodiment are Figure 1 a specific implementation method of S101.

[0053] S1011, the sample battery is subjected to charge-discharge according to a preset charge-discharge voltage range.

[0054] In the embodiment, the target charge-discharge voltage range of the battery made of the electrode material to be tested can be determined by performing charge-discharge test on the sample battery. The sample battery is a battery made of the electrode material to be tested and having stable performance. A charge-discharge voltage range having a width greater than the width of the standard charge-discharge voltage range is selected. The width of the charge-discharge voltage range refers to the difference between the maximum value and the minimum value of the voltage range, that is, the maximum value (for example, 4.6V) of the selected charge-discharge voltage range is greater than the maximum value (for example, 4.2V) of the standard charge-discharge voltage range, and the minimum value (for example, 1V) of the selected charge-discharge voltage range is less than the maximum value (for example, 3V) of the standard charge-discharge voltage range. The actual charge-discharge voltage range can be set according to the standard charge-discharge voltage range of the electrode material to be tested and the characteristics of the material to be tested. When the sample battery is subjected to charge-discharge based on the preset charge-discharge voltage range, the same charge-discharge rate as that in the cyclic charge-discharge process can be used, and the sample battery can be subjected to one or more times of charge-discharge.

[0055] S1012, the battery charge data and the battery discharge data of the sample battery in the charge-discharge process are obtained, and the battery charge data set and the battery discharge data set are obtained.

[0056] In the embodiment, when the sample battery is charged based on the preset charging and discharging voltage range, the battery charging data of the sample battery can be collected at a preset frequency, so that multiple charging data (corresponding to each sampling node) can be obtained in a single charging process, and the collected charging data can be various types of data such as voltage, capacity, and current, which can be used to determine the target charging and discharging voltage range.

[0057] Similarly, when the sample battery is discharged based on the preset charging and discharging voltage range, the battery discharging data of the sample battery can also be collected at a preset frequency, so that multiple discharging data (corresponding to each sampling node) can be obtained in a single discharging process, and the collected discharging data can also be various types of data.

[0058] S1013, determining the phase change termination voltage according to the battery charging data set, and determining the target phase change starting voltage according to the battery discharging data set; In the embodiment, in order to accelerate the cycle performance of the material, the lithium consumption of the battery can be increased, and the boundary of the voltage range can be widened. Different electrode materials have different boundary ranges that can be widened due to different preparation processes and raw materials. Therefore, in the embodiment, the phase change information of the material to be tested in the charging and discharging process is used to select the boundary of the voltage range. Through this determination method, the voltage range boundary values of different electrode materials to be tested can be quickly identified.

[0059] For different electrode materials to be tested, the charging data set and the discharging data set of the electrode materials to be tested can be used to determine the phase change information of the electrode materials to be tested in the charging process and the discharging process. For example, the phase change can be analyzed through voltage and capacity changes, or through current changes and voltage changes. Since the phase change is mainly reversible when the charging voltage is within a reasonable range, in order to accelerate lithium consumption, the phase change needs to enter an irreversible state. The voltage at which the last phase change occurs (i.e., the phase change termination voltage) can be used to determine the critical point of accelerated lithium consumption. When the charging voltage is greater than the critical point, the electrode material to be tested will be over-detrained, which will cause the internal structure to collapse. If the structural stability of the electrode material to be tested is weak, the lithium consumption will be larger, and the cycle life will be poorer. Therefore, the advantages and disadvantages of the cycle performance of the electrode material to be tested can be quickly exhibited, and the advantages and disadvantages of the cycle performance can be determined through fewer cycle tests.

[0060] In the discharging process, when the discharging voltage is in a reasonable range, the phase transition has little effect on the cycle performance. In order to accelerate lithium consumption, after the electrode material to be tested is fully embedded with lithium (i.e., discharged to the normal lower limit voltage), the electrode material with poor structural stability will change its structure, such as changing between the layered salt structure and the spinel structure, resulting in loss of lithium consumption. Therefore, the first phase transition voltage (i.e., the target starting phase transition voltage) in the voltage range below the normal lower limit voltage of the discharging voltage can be selected as the critical point for determining the accelerated lithium consumption. The target starting phase transition voltage is less than the lower limit voltage of the normal charging and discharging voltage range. When the discharging voltage is less than the critical point, the electrode material to be tested with poor structural stability will increase lithium consumption, and the corresponding cycle life will also be poor, so as to quickly show the advantages and disadvantages of the cycle performance of the electrode material to be tested.

[0061] In S1014, the target charging and discharging voltage range of the battery made of the electrode material to be tested is determined according to the termination phase transition voltage and the target starting phase transition voltage.

[0062] In this embodiment, the upper and lower limit voltages of the target charging and discharging voltage range can be determined according to the obtained termination phase transition voltage and target starting phase transition voltage, so as to obtain the target charging and discharging voltage range with a voltage range width greater than that of the standard charging and discharging voltage range.

[0063] In some embodiments, the sample battery is charged and discharged according to the preset charging and discharging voltage range, including: charging the sample battery to a first preset charging cutoff voltage according to a preset charging rate; wherein the first preset charging cutoff voltage is greater than the upper limit voltage of the standard charging and discharging voltage range; and discharging the sample battery to a second preset discharging cutoff voltage according to a preset discharging rate; wherein the second preset discharging cutoff voltage is less than the lower limit voltage of the standard charging and discharging voltage range.

[0064] In this embodiment, in order to make the width of the preset charging and discharging voltage range greater than the width of the corresponding standard charging and discharging voltage range of the battery, the upper limit voltage and the lower limit voltage of the preset charging and discharging voltage range can be expanded, so that the set charging and discharging voltage range can cover more than the upper limit voltage and the lower limit voltage of the standard charging and discharging voltage range, thereby analyzing the phase transition of the battery and determining a suitable target charging and discharging voltage range.

[0065] When charging the sample battery within a preset charge / discharge voltage range, it can be charged at a preset rate using a constant current until it reaches the first cutoff voltage (greater than the upper limit of the standard charge / discharge voltage range). When discharging the sample battery within the preset charge / discharge voltage range, it can be discharged at a preset rate using a constant current until it reaches the second cutoff voltage (less than the lower limit of the standard charge / discharge voltage range). This embodiment employs a method of simultaneously widening the upper and lower limits of the charge / discharge voltage range to perform overcharging and over-discharging during charging and discharging processes respectively, thereby accelerating battery lithium consumption and improving detection efficiency.

[0066] In the embodiments of this application, there are multiple strategies for determining the termination phase transition voltage based on the battery charging dataset and the target initiation phase transition voltage based on the battery discharging dataset. Please refer to [link to relevant documentation]. Figure 4 , Figure 4 This is a schematic flowchart illustrating another method for evaluating the performance of electrode materials provided in an embodiment of this application. Figure 4 S1013A to S1013C are respectively Figure 3 A specific implementation method of S1013.

[0067] S1013A, determine the first differential capacity curve based on the battery charging voltage and battery charging capacity of the battery charging data. S1013B, determine the second differential capacity curve based on the battery discharge voltage and battery discharge capacity of the battery discharge data. S1013C, obtain the first battery voltage corresponding to the termination phase peak in the first differential capacity curve, and obtain the second battery voltage corresponding to the target starting phase peak in the second differential capacity curve, to obtain the termination phase transition voltage and the target starting phase transition voltage respectively.

[0068] In this embodiment, the battery charging dataset contains battery charging data corresponding to multiple detection time points. There can also be various types of battery charging data. This embodiment takes battery charging data as battery charging voltage and battery charging capacity, and the electrode material to be tested as ternary material as an example to illustrate the determination of the target phase transition voltage.

[0069] The differential capacity value, i.e., the capacity change corresponding to a unit voltage change (dQ / dV), can be calculated based on the battery charging voltage and battery charging capacity during the charging phase. dQ / dV = (Q...) n+1 -Q n ) / (V n+1 -V n ), Q n V represents the battery capacity at the nth second. n Let be the battery voltage value at the nth second. Thus, the differential capacity curve of the sample battery during the charging phase is shown below, for example... Figure 5 As shown, Figure 5The horizontal axis in the figure is the battery voltage, and the vertical axis is the differential capacity value. The phase state information of the electrode material in the sample battery during the charging process can be seen from the differential capacity curve, and the target phase transition voltage can be determined according to the last characteristic peak (phase state peak) in the charging differential capacity curve. Figure 5 It can be seen from the figure that multiple characteristic peaks appear during the charging process, which is a signal of the ordered phase transition within the layered phase. These peaks are mainly distributed in the voltage interval of 3.4V to 4.2V, and the phase transition in the interval is mostly reversible, which has little effect on the cycle performance. The voltage value corresponding to the last characteristic peak (phase state peak) in the charging differential capacity curve can be obtained, that is, the termination phase transition voltage can be determined.

[0070] Similarly, the battery discharge data set also contains battery discharge data corresponding to multiple detection time nodes, and the type of battery discharge data can also be multiple. In this embodiment, the battery discharge data is taken as the battery discharge voltage and the battery discharge capacity, and the electrode material to be tested is taken as the ternary material to illustrate the determination of the target phase transition voltage.

[0071] Similarly, based on the battery discharge voltage and the battery discharge capacity in the discharge stage, the differential capacity value, that is, the capacity change corresponding to the unit voltage change (dQ / dV), is calculated. Thus, the differential capacity curve of the sample battery in the discharge stage, for example, Figure 6 as shown in the figure, Figure 6 The horizontal axis in the figure is the battery voltage, and the vertical axis is the differential capacity value. The phase state information of the electrode material in the sample battery during the charging process can be seen from the differential capacity curve, and the target phase transition voltage can be determined according to the last characteristic peak (phase state peak) in the charging differential capacity curve. Figure 6 It can be seen from the figure that multiple characteristic peaks appear during the charging process, which is a signal of the ordered phase transition within the layered phase. These peaks are mainly distributed in the voltage interval of 3.4V to 4.2V, and the phase transition in the interval is mostly reversible, which has little effect on the cycle performance. The voltage value corresponding to the last characteristic peak (phase state peak) in the charging differential capacity curve can be obtained, that is, the termination phase transition voltage can be determined.

[0072] Therefore, by determining the charging differential capacity curve and the discharge differential capacity curve according to the battery charging data set and the battery discharge data set, the phase transition information of the battery during the charging and discharging process can be obtained according to the characteristic peaks in the curve, so that the target phase transition voltage can be quickly and accurately determined.

[0073] In some embodiments, according to the termination phase transition voltage and the target initial phase transition voltage, the target charging and discharging voltage range of the battery made of the electrode material to be tested is determined, including: obtaining the sum of the termination phase transition voltage and a first preset threshold to obtain a target termination phase transition voltage; obtaining the difference between the target initial phase transition voltage and a second preset threshold to obtain a first target initial phase transition voltage; taking the target termination phase transition voltage as the minimum charging upper limit voltage; taking the first target initial phase transition voltage as the maximum discharging lower limit voltage; and determining the target charging and discharging voltage range of the battery made of the electrode material to be tested based on the minimum charging upper limit voltage and the maximum discharging lower limit voltage.

[0074] In the present embodiment, in order to accelerate the evaluation, after the termination phase change voltage and the target starting phase change voltage are determined, the two phase change voltage values can also be processed to expand the boundaries of the target charge and discharge voltage range. Thus, after the termination phase change voltage is obtained, the voltage value can also be added by a preset threshold, for example, in the charge differential capacity curve of Figure 5 4.2V, the termination phase change voltage can be added by the preset threshold, 4.2V is taken as the target termination phase change voltage, and the target termination phase change voltage is taken as the minimum charge upper limit voltage, that is, the upper limit voltage of the target charge and discharge voltage range can be ≥4.2V (that is, the platform voltage inflection point position corresponding to the material to be tested).

[0075] Similarly, after the target starting phase change voltage is obtained, the voltage value can also be subtracted by a preset threshold, for example, in the discharge differential capacity curve of Figure 6 1.7V, the target starting phase change voltage can be subtracted by the preset threshold, 1.4V is taken as the new target starting phase change voltage, and the new target starting phase change voltage is taken as the maximum discharge lower limit voltage, that is, the lower limit voltage of the target charge and discharge voltage range can be ≤1.4V (that is, the inflection point position on the left side of the target starting phase).

[0076] In some embodiments, based on the minimum charge upper limit voltage and the maximum discharge lower limit voltage, the target charge and discharge voltage range of the battery made of the electrode material to be tested is determined, comprising: obtaining the corrosion critical voltage of the current collector corresponding to the battery; taking the corrosion critical voltage of the current collector as the maximum charge upper limit voltage; based on the minimum charge upper limit voltage, the maximum charge upper limit voltage and the maximum discharge lower limit voltage, determining the target charge and discharge voltage range of the battery made of the electrode material to be tested.

[0077] The current collector is the core component of lithium battery that carries electrode active material and collects and transmits current, directly affecting the conductivity efficiency and structural stability of the battery. The corrosion critical voltage is the voltage turning point of the current collector from the stable state to the electrochemical corrosion state. For example, when the voltage of the current collector is lower than the corrosion critical voltage (such as the corrosion critical voltage of the aluminum foil current collector is 4.6V to 4.7V), the surface of the current collector can remain stable and no obvious oxidation corrosion reaction occurs. When the voltage exceeds the corrosion critical voltage, the oxidation-reduction balance of the current collector surface is broken, the thermodynamic driving force of the corrosion reaction is sufficient, and the corrosion phenomenon (such as current increase and current collector dissolution) can be detected.

[0078] Therefore, by obtaining the corrosion critical voltage of the current collector in the battery and taking the corrosion critical voltage as the maximum charge upper limit voltage, the excessive charge upper limit voltage leads to the corrosion of the current collector, affecting the accuracy of the cycle performance test.

[0079] In some embodiments, the battery is subjected to cyclic charging and discharging in a target charging and discharging voltage range, including: sequentially charging the battery to an upper limit voltage of the target charging and discharging voltage range and discharging the battery to a lower limit voltage of the target charging and discharging voltage range according to a preset number of cycles and a preset charging and discharging strategy; wherein the battery charging event and the battery discharging event are separated by a preset time length.

[0080] Cyclic charging and discharging refers to a process in which the test battery is charged to a charging cutoff voltage according to a charging strategy, and then the test battery is discharged to a discharging cutoff voltage according to a discharging strategy. A single cycle will complete a complete charging to a full state of charge and discharging to a preset cutoff voltage.

[0081] In the present embodiment, by obtaining the target charging and discharging voltage range, the charging cutoff voltage and the discharging cutoff voltage during charging and discharging of the test battery can be determined, thereby providing guidance for control parameters of the battery prepared from the test electrode material subjected to cyclic charging and discharging. The charging and discharging control strategy according to the target charging and discharging voltage range can be various, for example, according to the charging and discharging rate type, there can be a fixed charging and discharging rate strategy, a variable rate charging and discharging strategy. When the battery is subjected to charging and discharging with a fixed charging and discharging rate, a single preset rate constant current charging can be used to charge to the upper limit voltage of the target charging and discharging voltage range. When the battery is subjected to charging and discharging with a variable rate, the rate can be updated when charging or discharging for a certain time or cycle reaches a preset number of times, so that the battery is charged or discharged to the cutoff voltage with multiple rates, simulating the mixed scenario of fast charging, slow charging and high power discharging in practice, and the structural stability of the material under high rate can be evaluated.

[0082] After the battery is charged and discharged, a certain time length (for example, 10 minutes) can be waited before the battery discharging control or the battery charging control is performed, so that the battery is in a stable state when the charging and discharging starts, which is beneficial to ensure the accuracy of the collected data.

[0083] The number of cycles can be determined according to the test requirements and the material characteristics. Since the target charging and discharging voltage range used in the present embodiment is greater than the standard charging and discharging voltage range of the battery, the battery can be accelerated to be consumed, and the number of cycles used can be much smaller than the number of cycles of the standard test (laboratory stage), for example, the number of cycles of the standard test (laboratory stage) is 50 to 200 times, and the number of cycles used in the present embodiment can be 10 to 30 times, effectively reducing the detection period and improving the detection efficiency. By using the preset charging and discharging strategy and the target charging and discharging voltage range, the battery prepared from the test material is subjected to cyclic charging and discharging, which can match different actual charging and discharging scenarios, is beneficial to improve the reliability of the test, and can reduce the cycle test period, effectively improving the detection efficiency.

[0084] In some embodiments, the charging strategy in the preset charging and discharging strategy comprises: charging the battery at a first preset charging rate to an upper limit voltage of the target charging and discharging voltage range; if it is detected that the voltage of the battery reaches the upper limit voltage, charging the battery at a second preset charging rate to the upper limit voltage; wherein the second preset charging rate is less than the first preset charging rate; or, if it is detected that the voltage of the battery reaches the upper limit voltage, charging the battery at the upper limit voltage to a current of the battery reaching the second preset charging rate; wherein the second preset charging rate is less than the first preset charging rate.

[0085] In the present embodiment, the charging strategy adopted is a charging mode of charging the battery at a fixed rate.

[0086] That is, the battery under test is charged at a preset charging rate, and the charging rate remains unchanged throughout the charging process. For example, the battery under test is charged at a charging rate of ≤0.33C, and the same charging rate is used for charging each time. Using the fixed rate charging mode can ensure that the degradation trend and other cycle performance in the cycle performance evaluation are only caused by material aging itself, rather than rate variation interference, so as to accurately compare the performance differences of different cycle numbers.

[0087] The present embodiment adopts a two-stage constant current charging mode. In the first stage, a small rate such as 0.1C (C is the rated capacity of the battery, and if the battery capacity is 1000mAh, 0.1C is 100mA) can be used for constant current charging until the battery voltage reaches a set cut-off voltage V1, that is, the upper limit value of the charging and discharging voltage range, for example, V1≥4.2V for ternary materials. Using a small rate of 0.1C for constant current charging can avoid the problem of low test accuracy caused by excessive polarization. After the first stage of charging is completed, the charging is not stopped directly, but is switched to a second charging rate lower than the first charging rate in the first stage, such as 0.01C (if the battery capacity is 1000mAh, 0.01C is 10mA), and constant current charging is continued, and V1 is also used as the charging cut-off voltage (the charging is stopped when the voltage reaches V1).

[0088] In addition, the second stage charging mode can also use a step-down rate constant current charging mode, for example, the charging rate 0.1C is reduced to 0.05C to charge to V1, and then the charging rate 0.05C is reduced to 0.01C to charge to V1, so as to reduce the polarization. A constant voltage charging mode can also be used, that is, charging at V1 until the current is reduced to a preset current such as 0.01C to stop charging, so as to achieve depolarization full charging.

[0089] The first charging stage uses a charging method such as a charging rate of 0.1C, which can quickly charge the battery to a state close to full charge. However, at this time, there is polarization in the electrode, and the surface voltage has reached the charging cutoff voltage V1 due to the diffusion lag of lithium ions, and the internal is still not fully charged. Although the battery voltage reaches the upper limit value at a current intensity of 0.1C, if the charging current is reduced, the polarization effect in the battery will weaken, and it can continue to accept a small amount of charge, and the voltage will also drop a little. Therefore, when the second charging stage switches to a smaller current than the first stage, the charging polarization (reverse voltage that hinders charging) in the battery will decrease, causing the actual voltage of the battery to drop temporarily below V1, and the battery will slowly absorb the charge with a current of 0.01C. The voltage will rise again. When the voltage rises to the set V1 again, it means that even at a small current such as 0.01C, the battery cannot accept any more charge, and the entire charging process is truly stopped, and the battery is fully charged. By using low-rate supplemental charging, it can ensure that the battery is fully charged and reduce the capacity measurement error caused by polarization.

[0090] In some embodiments, the discharge strategy in the preset charging and discharging strategy includes: discharging the battery at a first preset charging rate to a lower limit voltage of the charging and discharging voltage range; if it is detected that the voltage of the battery reaches the lower limit voltage, discharging the battery at a second preset charging rate to the lower limit voltage; wherein the second preset charging rate is less than the first preset charging rate; or, if it is detected that the voltage of the battery reaches the lower limit voltage, discharging the battery at a constant voltage to a current of the battery reaching a second preset charging rate; wherein the second preset charging rate is less than the first preset charging rate.

[0091] With the charging stage type, the present embodiment uses a two-stage constant current discharge method. The first stage can use a small rate such as 0.1C (C is the rated capacity of the battery, if the battery capacity is 1000mAh, 0.1C is 100mA) to discharge at a constant current until the battery voltage reaches the set discharge cutoff voltage V2, which is the lower limit value of the charging and discharging voltage range, for example, V2≤1.7V for ternary materials. Using a small rate of 0.1C to discharge at a constant current can avoid the problem of low test accuracy due to excessive polarization. After the first stage of discharging is completed, instead of stopping discharging directly, it is switched to a second discharge rate lower than the first discharge rate of the first stage, such as 0.01C (if the battery capacity is 1000mAh, 0.01C is 10mA) to continue discharging at a constant current, and V2 is also used as the discharge cutoff voltage (the voltage reaches V2 to stop).

[0092] Similarly, the second stage discharge mode can also adopt a step-down rate constant-current discharge mode, for example, the discharge rate is reduced from 0.1C to 0.05C to V2, and then the discharge rate is reduced from 0.05C to 0.01C to V2, so as to reduce polarization. A constant-voltage discharge mode can also be adopted, and the battery is discharged at V2 until the current decreases to a preset current such as 0.01C, and then the discharge is stopped, so as to achieve depolarization full discharge.

[0093] In the first discharge stage, low rate (such as 0.1C) discharge is adopted, which can simulate the working state of the battery in a low-power consumption scenario. This stage can fully activate the active material inside the battery, so that lithium ions have enough time to complete deintercalation and migration. In the second discharge stage, ultra-low rate (such as 0.01C) discharge is adopted, which belongs to deep fine discharge. The polarization phenomenon (voltage virtual drop caused by excessive current) of the battery can be eliminated or reduced, so that the battery can release as much as possible the stored electric quantity, achieve full discharge state, and ensure the accuracy of capacity test.

[0094] In some embodiments, the charge-discharge data includes a discharge capacity, and based on the charge-discharge data, the cycle performance of the to-be-tested electrode material is evaluated, including: obtaining discharge capacities corresponding to a plurality of target cycle times; determining capacity retention rates corresponding to the target cycle times according to the discharge capacities; and evaluating the cycle performance of the to-be-tested electrode material based on all the capacity retention rates.

[0095] In this embodiment, the cycle performance evaluation implementation of the to-be-tested electrode material is described by taking the discharge capacity as an example of the charge-discharge data. The discharge capacity refers to the total electric quantity that can be released by the battery in one complete discharge process under a preset charge-discharge condition (such as fixed rate and cutoff voltage). The discharge capacity can be collected in an interval or continuously, for example, the discharge capacity after each cycle can be collected (for example, every two cycles), or the discharge capacity after each cycle can be collected. According to the discharge capacity after each cycle, the capacity retention rate can be calculated, so as to compare the discharge capacities at different stages through the capacity retention rate, evaluate the degree of battery performance degradation, and judge the advantages and disadvantages of the cycle performance of the to-be-tested electrode material. The capacity retention rate is the ratio of the discharge capacity of the battery made of the to-be-tested electrode material after N cycles of charge-discharge to the discharge capacity after the initial cycle of charge-discharge. The discharge capacity after the initial cycle of charge-discharge can be the discharge capacity after the first cycle or the first few stable cycles, which can be used as a performance benchmark. For example, if the initial discharge capacity of the battery is 1000mAh, and the discharge capacity after N cycles of charge-discharge is 800mAh, then the capacity retention rate is 800 / 1000=0.8.

[0096] In addition, the discharge capacity can be obtained to calculate the remaining capacity retention rate, i.e., the current remaining discharge capacity / initial discharge capacity. The initial capacity can be the initial discharge capacity obtained by the first charge-discharge test, and the current remaining discharge capacity is the actual discharge capacity of the battery after cycling. For example, if the initial discharge capacity of a battery to be tested is 500 mAh, and the actual discharge capacity after M cycles of charge-discharge is 420 mAh, then the remaining capacity retention rate is 420 / 500 = 0.84, i.e., the current remaining initial capacity is 84%. The remaining capacity retention rate is similar to the capacity retention rate principle.

[0097] After determining the capacity retention rate or the remaining capacity retention rate corresponding to the target cycle number, it can be determined whether the capacity retention rate after a preset number of cycles can still reach a preset threshold. If so, it can be determined that the cycle performance of the electrode material to be tested meets the requirements and has good cycle performance. The capacity retention rate corresponding to a plurality of target cycle numbers can also be plotted to draw a capacity retention rate curve, and the cycle performance of the material to be tested can be evaluated by the downward trend of the curve. For example Figure 7 The capacity retention rate curve is shown in FIG. 1, where the horizontal axis is the cycle number and the vertical axis is the capacity retention rate. It can be seen that the capacity retention rate curves of the electrode materials A and B (for example, ternary materials with a nickel content of 50% to 65%) have a slow downward trend as a whole, indicating that the cycle performance of the electrode materials to be tested is good. The capacity retention rate curves of the electrode materials C and D (for example, ternary materials with a nickel content of 70% to 85%) have a faster downward trend, and their cycle performance is poor.

[0098] In addition, it can be seen from Figure 7 that the charge-discharge strategy provided in the embodiment can obtain effective cycle performance evaluation parameters for cycle performance evaluation after about 10 cycles, quickly determine the cycle performance of the material to be tested, and improve the efficiency of the pre-detection.

[0099] In some embodiments, the battery prepared from the electrode material to be tested is a half battery.

[0100] It should be understood that the related art uses a full battery for cycle performance evaluation. Since the preparation of a full battery takes several days, plus the required months of detection period, the entire detection period is too long, and the research and development material used for preparing the full battery is at least kilogram level, which undoubtedly leads to the fact that most of the research and development materials at the laboratory stage cannot be effectively detected for life, so that the detection method cannot be flexibly adapted to various detection scene requirements.

[0101] The half-cell is used as the test object in the embodiment, the mass of the electrode material to be tested can be reduced from kilogram level to gram level (e.g., ≤10 g), and the test battery can be completed within several hours, which greatly saves the test period of the storage performance compared with the production period of several weeks of the finished battery. The whole preparation and test period can be reduced from several months to 10 days, which effectively improves the detection efficiency and saves the material resources.

[0102] In some embodiments, the process of preparing the battery from the electrode material to be tested includes: preparing electrode slurry from the electrode material to be tested, coating the electrode slurry on the current collector to prepare the electrode sheet, and assembling the electrode sheet cut to a preset size to prepare the battery.

[0103] The embodiment provides a specific process of preparing a battery from an electrode material to be tested. The core process of preparing the battery from the electrode material to be tested is to prepare slurry from the electrode material to be tested, uniformly coat the slurry on the current collector, dry and roll the slurry to obtain the electrode sheet, and then assemble the electrode sheet to obtain the battery.

[0104] The process of preparing the slurry includes: weighing the materials according to the formula proportion, mainly including the electrode material to be tested (e.g., ternary material), conductive agent (e.g., carbon black), binder (e.g., PVDF) and solvent (e.g., NMP), the mass ratio of the electrode material to be tested can be 85% to 99%, the mass ratio of the conductive agent can be 1% to 3%, the mass ratio of the binder can be 1% to 5%, and the mass ratio of the three can be 97%:1%:2%.

[0105] The conductive agent and the solvent are mixed and stirred at high speed until they are uniformly dispersed to form conductive slurry; then the electrode material to be tested is added, and the powder is prevented from agglomeration by low-speed stirring; finally, the binder is added, and the mixture is stirred at high speed for a period of time to ensure that all the materials are fully mixed. The above stirring process can be performed in a vacuum stirrer, and the overall stirring time is ≥20 min. Then, the coating device is used to coat the battery-level current collector (thickness 5 to 20 microns, and the current collector used in the embodiment is an aluminum foil current collector with a thickness of 10 microns) to a thickness of 100 to 300 microns (the thickness used in the embodiment is 150 microns); then the electrode sheet is transferred to a high-temperature drying oven and dried at a temperature of ≥70℃ (for ≥1 h); the electrode sheet is cold-pressed in a roller press at a pressure of 0.5 to 2 MPa; the electrode sheet is fully dried in a vacuum oven (temperature ≥110℃) (for ≥10 h); the electrode sheet is cut into a circular sheet with a diameter of, for example, 16 mm; the battery is assembled in a glove box in an inert gas atmosphere free of air, and the counter electrode of the button-type half-cell can be lithium metal; 200 microliters of electrolyte is injected; the prepared battery is fully rested for 12 h or more to allow the electrolyte to fully soak, and a battery that can be tested is obtained.

[0106] Based on the technical solution of the above embodiment of the present application, the target charge-discharge voltage range of the battery made of the electrode material to be tested is obtained, the width of the target charge-discharge voltage range is greater than the width of the standard charge-discharge voltage range of the battery, and the battery is subjected to cyclic charge-discharge according to the target charge-discharge voltage range, the charge-discharge data of the battery in the cyclic charge-discharge process is obtained, and the cycle performance of the electrode material to be tested is evaluated according to the charge-discharge data. By widening the charge-discharge voltage range, the lithium consumption of the battery of the electrode material to be tested is increased, so that the cycle performance evaluation of the electrode material to be tested can be performed according to the charge-discharge data in a few cyclic charge-discharge processes, the test period is effectively shortened, and the test efficiency is improved.

[0107] In order to better illustrate the electrode material performance evaluation scheme in the foregoing embodiment, the embodiment of the present application further provides a detailed electrode material performance evaluation method. Please refer to Figure 8 , Figure 8 FIG. 1 is a detailed flowchart of the electrode material performance evaluation method provided by some embodiments of the present application, which includes the following steps: S201, performing charge-discharge on the sample battery according to a preset charge-discharge voltage range; S202, obtaining battery charge data and battery discharge data of the sample battery in the charge-discharge process, and obtaining a battery charge data set and a battery discharge data set, respectively; S203, determining a first differential capacity curve according to the battery charge voltage and the battery charge capacity in the battery charge data set; S204, determining a second differential capacity curve according to the battery discharge voltage and the battery discharge capacity in the battery discharge data set; S205, obtaining a first battery voltage corresponding to a terminal phase change peak in the first differential capacity curve, and obtaining a second battery voltage corresponding to a target initial phase change peak in the second differential capacity curve, and obtaining a terminal phase change voltage and a target initial phase change voltage, respectively; S206, determining a target charge-discharge voltage range of the battery made of the electrode material to be tested according to the terminal phase change voltage and the target initial phase change voltage; S207, performing cyclic charge-discharge on the battery in the target charge-discharge voltage range, and obtaining discharge capacities corresponding to a plurality of target cycle numbers; S208, determining a capacity retention rate corresponding to the target cycle number according to the discharge capacities; S209, evaluating the cycle performance of the electrode material to be tested based on all the capacity retention rates.

[0108] Based on the technical solutions of the embodiments of the present application, the first differential capacity curve and the second differential capacity curve are determined according to the battery charging voltage, the battery charging capacity in the battery charging data set and the battery discharging voltage, the battery discharging capacity in the battery discharging data set, the battery voltage corresponding to the terminal phase change peak in the first differential capacity curve and the battery voltage corresponding to the target starting phase change peak in the second differential capacity curve are obtained, the terminal phase change voltage and the target starting phase change voltage are obtained, and the target charging and discharging voltage range of the battery made of the electrode material to be measured is determined. By determining the charging differential capacity curve and the discharging differential capacity curve according to the battery charging data set and the battery discharging data set, the phase change information of the battery in the charging and discharging process can be obtained according to the characteristic peaks in the curves, so that the target phase change voltage can be quickly and accurately determined. The width of the target charging and discharging voltage range determined according to the terminal phase change voltage and the target starting phase change voltage is greater than the width of the standard charging and discharging voltage range of the battery. The battery is subjected to cyclic charging and discharging according to the target charging and discharging voltage range, the discharging capacity of the battery in the cyclic charging and discharging process is obtained, and the cycle performance of the electrode material to be measured is evaluated according to the discharging capacity. By widening the charging and discharging voltage range, the lithium consumption of the battery of the electrode material to be measured is increased, so that the cycle performance evaluation of the electrode material to be measured can be performed according to the discharging capacity in a few cycles of the cyclic charging and discharging process, the test period is effectively shortened, and the test efficiency is improved.

[0109] It should be understood that the size of the serial number of each step in the embodiments does not mean the order of execution of the steps, and the execution order of each step should be determined according to its function and inherent logic, and should not constitute the only limitation on the implementation process of the embodiments of the present application.

[0110] Based on the same inventive concept, the embodiments of the present application also provide related products for implementing the above-mentioned method. It should be understood that the implementation scheme of the related products for solving the problem is similar to the above-mentioned method.

[0111] The embodiments of the present application also provide an electrode material performance evaluation device. Please refer to Figure 9 , Figure 9 A structural schematic diagram of an electrode material performance evaluation device provided for some embodiments of the present application. The electrode material performance evaluation device 300 can include an acquisition module 301, a charging and discharging module 302, and an evaluation module 303, as follows: The acquisition module 301 is configured to acquire a target charging and discharging voltage range of a battery made of an electrode material to be measured. The width of the target charging and discharging voltage range is greater than the width of a standard charging and discharging voltage range of the battery. The charging and discharging module 302 is configured to perform cyclic charging and discharging on the battery in the target charging and discharging voltage range and to obtain charging and discharging data of the battery in the cyclic charging and discharging process. The charging and discharging data includes a discharging capacity. The evaluation module 303 is configured to evaluate the cycle performance of the electrode material under test based on the charge and discharge data.

[0112] In some embodiments, the acquisition module 301 can be configured to: charge and discharge the sample battery according to a preset charge and discharge voltage range; wherein the preset charge and discharge voltage range has a width greater than that of the standard charge and discharge voltage range; acquire battery charge data and battery discharge data of the sample battery during the charging and discharging process to obtain a battery charge data set and a battery discharge data set, respectively; determine the termination phase transition voltage based on the battery charge data set, and determine the target starting phase transition voltage based on the battery discharge data set; wherein the target starting phase transition voltage is less than the lower limit voltage of the standard charge and discharge voltage range; determine the target charge and discharge voltage range of the battery made of the electrode material under test based on the termination phase transition voltage and the target starting phase transition voltage; the battery is a half battery, and the process of making the battery from the electrode material under test includes: making electrode slurry from the electrode material under test, and coating the electrode slurry on a current collector to make a pole piece; assembling the pole piece cut to a preset size to obtain the battery.

[0113] In some embodiments, the charge and discharge module 302 can also be configured to: charge the sample battery to a first preset charge cutoff voltage according to a preset charge rate; wherein the first preset charge cutoff voltage is greater than the upper limit voltage of the standard charge and discharge voltage range; and discharge the sample battery to a second preset discharge cutoff voltage according to a preset discharge rate; wherein the second preset discharge cutoff voltage is less than the lower limit voltage of the standard charge and discharge voltage range.

[0114] In some embodiments, the acquisition module 301 can also be configured to: determine a first differential capacity curve based on the battery charge voltage and the battery charge capacity in the battery charge data set; determine a second differential capacity curve based on the battery discharge voltage and the battery discharge capacity in the battery discharge data set; obtain a first battery voltage corresponding to the termination phase state peak in the first differential capacity curve, and obtain a second battery voltage corresponding to the target starting phase state peak in the second differential capacity curve, to obtain the termination phase transition voltage and the target starting phase transition voltage, respectively.

[0115] In some embodiments, the acquisition module 301 can also be configured to: obtain a target termination phase transition voltage by summing the termination phase transition voltage and a first preset threshold; obtain a first target starting phase transition voltage by subtracting a second preset threshold from the target starting phase transition voltage; take the target termination phase transition voltage as the minimum charge upper limit voltage; take the first target starting phase transition voltage as the maximum discharge lower limit voltage; and determine the target charge and discharge voltage range of the battery made of the electrode material under test based on the minimum charge upper limit voltage and the maximum discharge lower limit voltage.

[0116] In some embodiments, the acquisition module 301 can be further configured to acquire a corrosion critical voltage of the current collector corresponding to the battery; and take the corrosion critical voltage of the current collector as a maximum charging upper limit voltage; and determine a target charging and discharging voltage range of the battery made of the electrode material to be tested based on the minimum charging upper limit voltage, the maximum charging upper limit voltage and the maximum discharging lower limit voltage.

[0117] In some embodiments, the charging and discharging module 302 can be configured to sequentially charge the battery to an upper limit voltage of the target charging and discharging voltage range and discharge the battery to a lower limit voltage of the target charging and discharging voltage range according to a preset number of cycles and a preset charging and discharging strategy; and the battery charging event and the battery discharging event are separated by a preset time length.

[0118] In some embodiments, the charging and discharging module 302 can be configured to charge the battery to the upper limit voltage of the target charging and discharging voltage range at a first preset charging rate; if it is detected that the voltage of the battery reaches the upper limit voltage, charge the battery to the upper limit voltage at a second preset charging rate; or, if it is detected that the voltage of the battery reaches the upper limit voltage, charge the battery to the upper limit voltage at a constant voltage until the current of the battery reaches the second preset charging rate; and the second preset charging rate is less than the first preset charging rate.

[0119] In some embodiments, the charging and discharging module 302 can be configured to discharge the battery to the lower limit voltage of the charging and discharging voltage range at a first preset discharging rate; if it is detected that the voltage of the battery reaches the lower limit voltage, discharge the battery to the lower limit voltage at a second preset discharging rate; or, if it is detected that the voltage of the battery reaches the lower limit voltage, discharge the battery to the lower limit voltage at a constant voltage until the current of the battery reaches the second preset discharging rate; and the second preset discharging rate is less than the first preset discharging rate.

[0120] In some embodiments, the charging and discharging data includes a discharging capacity, and the evaluation module 303 can be configured to acquire a plurality of target cycle numbers corresponding to the discharging capacity; determine a capacity retention rate corresponding to the target cycle number according to the discharging capacity; and evaluate the cycle performance of the electrode material to be tested based on all the capacity retention rates.

[0121] It should be noted that the electrode material performance evaluation method in the foregoing embodiments can be implemented based on the electrode material performance evaluation device provided in the present embodiment. It can be clearly understood by those skilled in the art that, for the convenience and brevity of description, the specific working process of the electrode material performance evaluation device described in the present embodiment can refer to the corresponding process in the foregoing method embodiments, which will not be described herein.

[0122] Based on the technical solutions of the above-mentioned embodiments of the present application, the target charge-discharge voltage range of the battery made of the electrode material to be tested is obtained, the width of the target charge-discharge voltage range is greater than the width of the standard charge-discharge voltage range of the battery, and the battery is subjected to cyclic charge-discharge according to the target charge-discharge voltage range, the charge-discharge data of the battery in the cyclic charge-discharge process is obtained, and the cycle performance of the electrode material to be tested is evaluated according to the charge-discharge data. By widening the charge-discharge voltage range, the lithium consumption of the battery of the electrode material to be tested is increased, so that the cycle performance evaluation of the electrode material to be tested can be performed according to the charge-discharge data in the less times of cyclic charge-discharge process, the test period is effectively shortened, and the test efficiency is improved.

[0123] In addition, the present application also provides an electrode material performance evaluation system, please refer to Figure 10 , Figure 10 The structural schematic diagram of the electrode material performance evaluation system provided by some embodiments of the present application is shown in the figure, the electrode material performance evaluation system 400 can be used to realize the electrode material performance evaluation method in the foregoing embodiments, and mainly includes a processor 401 and a memory 402. The processor 401 is electrically connected with the memory 402.

[0124] The processor 401 is the control center of the electrode material performance evaluation system 400, and connects all parts of the electrode material performance evaluation system through various interfaces and lines. The processor 401 executes various functions of the electrode material performance evaluation system and processes data by running or calling the computer programs stored in the memory 402 and calling the data stored in the memory 402, so as to monitor the electrode material performance evaluation system as a whole.

[0125] The memory 402 can be used to store software programs and modules. The processor 401 executes various functions and data processing by running the computer programs and modules stored in the memory 402. The memory 402 can mainly include a program storage area and a data storage area. The program storage area can store an operating system, at least one computer program required by a function, etc. The data storage area can store data created according to the use of the electrode material performance evaluation system, etc.

[0126] In addition, the memory 402 can include a high-speed random access memory, and can also include a non-volatile memory, such as at least one magnetic disk storage device, a flash memory device, or other volatile solid-state memory device. Accordingly, the memory 402 can also include a memory controller to provide access of the processor 401 to the memory 402.

[0127] In this embodiment, the processor 401 in the electrode material performance evaluation system 400 loads the instructions corresponding to the processes of one or more computer programs into the memory 402 and runs the computer programs stored in the memory 402 by the processor 401 to implement various functions according to the following steps. For example, a target charge-discharge voltage range of a battery made of the electrode material to be tested is obtained; the width of the target charge-discharge voltage range is greater than the width of a standard charge-discharge voltage range of the battery; the battery is subjected to cyclic charge-discharge in the target charge-discharge voltage range, and charge-discharge data of the battery in the cyclic charge-discharge process is obtained; and the cycle performance of the electrode material to be tested is evaluated based on the charge-discharge data.

[0128] For reference Figure 11 which shows a structural schematic diagram of a computer readable storage medium provided by an embodiment of the present application. The computer readable storage medium 500 stores program code 501, which can be invoked by a processor to execute the methods described in the above method embodiments.

[0129] The computer readable storage medium 500 can be an electronic storage such as a flash memory, an EEPROM (electrically erasable programmable read-only memory), an EPROM, a hard disk, or a ROM. Alternatively, the computer readable storage medium 500 includes a non-transitory computer readable medium. The computer readable storage medium 500 has a storage space for the program code 501 to execute any of the above methods. These program codes can be read from or written into one or more computer program products. The program code 501 can be compressed in an appropriate form, for example.

[0130] Since the instructions stored in the storage medium can execute the steps in any of the electrode material performance evaluation methods provided by the embodiments of the present application, the beneficial effects that can be achieved by any of the electrode material performance evaluation methods provided by the embodiments of the present application can be achieved. Details are described in the above embodiments, which will not be described here.

[0131] In several embodiments provided in the present application, it should be understood that the disclosed apparatus and method can be implemented in other manners. For example, the described apparatus embodiments are merely schematic. For example, the division of the modules is merely a logical function division. There can be another division manner for the actual implementation, for example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between different modules can be indirect couplings or communication connections through some interfaces, and electrical, mechanical or other forms.

[0132] The modules described as separated components can or can not be physically separated, and the components displayed as modules can or can not be physical modules, i.e., can be located in one place, or can be distributed on multiple network modules. Some or all of the modules can be selected according to actual needs to achieve the purposes of the embodiments.

[0133] In addition, each functional module in the various embodiments of the present application can be integrated in one processing module, or each module can be physically present alone, or two or more modules can be integrated in one module. The integrated module can be realized in the form of hardware or in the form of a software functional module.

[0134] If the integrated module is realized in the form of a software functional module and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a readable storage medium, and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the various embodiments of the method of the present application.

[0135] It should be noted that, for the foregoing method embodiments, the purposes of brief description are to express them as a combination of a series of actions, but those skilled in the art should know that the present application is not limited by the order of the actions described, because according to the present application, some steps can be performed in other orders or simultaneously. In addition, those skilled in the art should know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily all the necessary actions of the present application.

[0136] In the above embodiments, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0137] The above is the description of the electrode material performance evaluation method, device, system and storage medium provided by the present application. For those skilled in the art, according to the idea of the embodiments of the present application, the specific implementation and application range will be changed. In summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A method of evaluating the performance of an electrode material, characterized by, The method comprises: obtaining a target charge-discharge voltage range of a battery made of the electrode material to be tested; wherein the width of the target charge-discharge voltage range is greater than the width of a standard charge-discharge voltage range of the battery; cycling the battery in the target charge-discharge voltage range and obtaining charge-discharge data of the battery during the cycling; wherein the charge-discharge data comprises discharge capacity; based on the charge-discharge data, evaluating the cycle performance of the electrode material to be tested.

2. The method of evaluating the performance of an electrode material according to claim 1, wherein The method of obtaining the target charge-discharge voltage range of the battery made of the electrode material to be tested comprises: charging and discharging a sample battery according to a preset charge-discharge voltage range; wherein the width of the preset charge-discharge voltage range is greater than the width of the standard charge-discharge voltage range; obtaining battery charge data and battery discharge data of the sample battery during the charging and discharging, to obtain a battery charge data set and a battery discharge data set respectively; determining a terminal phase transition voltage according to the battery charge data set, and determining a target initial phase transition voltage according to the battery discharge data set; wherein the target initial phase transition voltage is less than the lower limit voltage of the standard charge-discharge voltage range; determining the target charge-discharge voltage range of the battery made of the electrode material to be tested according to the terminal phase transition voltage and the target initial phase transition voltage.

3. The method of claim 2, wherein The method of charging and discharging the sample battery according to the preset charge-discharge voltage range comprises: charging the sample battery to a first preset charging cutoff voltage according to a preset charging rate; wherein the first preset charging cutoff voltage is greater than the upper limit voltage of the standard charge-discharge voltage range; discharging the sample battery to a second preset discharging cutoff voltage according to a preset discharging rate; wherein the second preset discharging cutoff voltage is less than the lower limit voltage of the standard charge-discharge voltage range.

4. The method of claim 2, wherein The method of determining the terminal phase transition voltage according to the battery charge data set and determining the target initial phase transition voltage according to the battery discharge data set comprises: determining a first differential capacity curve according to the battery charge voltage and the battery charge capacity in the battery charge data set; determining a second differential capacity curve according to the battery discharge voltage and the battery discharge capacity in the battery discharge data set; obtaining a first battery voltage corresponding to a terminal phase state peak in the first differential capacity curve, and obtaining a second battery voltage corresponding to a target initial phase state peak in the second differential capacity curve, to obtain the terminal phase transition voltage and the target initial phase transition voltage respectively.

5. The method of claim 2, wherein The method of determining the target charge-discharge voltage range of the battery made of the electrode material to be tested according to the terminal phase transition voltage and the target initial phase transition voltage comprises: obtaining a target terminal phase transition voltage by adding a first preset threshold value to the terminal phase transition voltage; obtaining a first target initial phase transition voltage by subtracting a second preset threshold value from the target initial phase transition voltage; taking the target terminal phase transition voltage as a minimum charging upper limit voltage; taking the first target initial phase transition voltage as a maximum discharging lower limit voltage; determining the target charge-discharge voltage range of the battery made of the electrode material to be tested based on the minimum charging upper limit voltage and the maximum discharging lower limit voltage.

6. The method of claim 5, wherein The method comprises the following steps: obtaining the corrosion critical voltage of the current collector corresponding to the battery; taking the corrosion critical voltage of the current collector as the maximum charging upper limit voltage; determining the target charging and discharging voltage range of the battery made of the electrode material to be tested based on the minimum charging upper limit voltage, the maximum charging upper limit voltage and the maximum discharging lower limit voltage.

7. The method of claim 1, wherein The method comprises the following steps: obtaining the corrosion critical voltage of the current collector corresponding to the battery; taking the corrosion critical voltage of the current collector as the maximum charging upper limit voltage; 8. The method of claim 7, wherein determining the target charging and discharging voltage range of the battery made of the electrode material to be tested based on the minimum charging upper limit voltage, the maximum charging upper limit voltage and the maximum discharging lower limit voltage. The method comprises the following steps: carrying out cyclic charging and discharging on the battery in the target charging and discharging voltage range comprises: carrying out charging on the battery to the upper limit voltage of the target charging and discharging voltage range and carrying out discharging on the battery to the lower limit voltage of the target charging and discharging voltage range in turn according to a preset cycle number and a preset charging and discharging strategy; 9. The method of claim 7, wherein the method further comprises: wherein, the interval between the battery charging event and the battery discharging event is a preset time length. The charging strategy in the preset charging and discharging strategy comprises: carrying out constant current charging on the battery to the upper limit voltage of the target charging and discharging voltage range according to a first preset charging rate; if it is detected that the voltage of the battery reaches the upper limit voltage, carrying out constant current charging on the battery to the upper limit voltage according to a second preset charging rate; wherein, the second preset charging rate is smaller than the first preset charging rate; 10. The method of claim 1, wherein or, if it is detected that the voltage of the battery reaches the upper limit voltage, carrying out constant voltage charging on the battery to the upper limit voltage until the current of the battery reaches a second preset charging rate; wherein, the second preset charging rate is smaller than the first preset charging rate. The discharging strategy in the preset charging and discharging strategy comprises: carrying out constant current discharging on the battery to the lower limit voltage of the charging and discharging voltage range according to a first preset charging rate; if it is detected that the voltage of the battery reaches the lower limit voltage, carrying out constant current discharging on the battery to the lower limit voltage according to a second preset charging rate; wherein, the second preset charging rate is smaller than the first preset charging rate; 11. The method of evaluating the performance of an electrode material according to any one of claims 1 to 10, wherein or, if it is detected that the voltage of the battery reaches the lower limit voltage, carrying out constant voltage discharging on the battery to the lower limit voltage until the current of the battery reaches a second preset charging rate; wherein, the second preset charging rate is smaller than the first preset charging rate.

12. The method of evaluating the performance of an electrode material according to any one of claims 1 to 10, wherein The method comprises the following steps: obtaining the corrosion critical voltage of the current collector corresponding to the battery; taking the corrosion critical voltage of the current collector as the maximum charging upper limit voltage; determining the target charging and discharging voltage range of the battery made of the electrode material to be tested based on the minimum charging upper limit voltage, the maximum charging upper limit voltage and the maximum discharging lower limit voltage.

13. An electrode material performance evaluation device, characterized by comprising: The method comprises the following steps: obtaining the corrosion critical voltage of the current collector corresponding to the battery; taking the corrosion critical voltage of the current collector as the maximum charging upper limit voltage; determining the target charging and discharging voltage range of the battery made of the electrode material to be tested based on the minimum charging upper limit voltage, the maximum charging upper limit voltage and the maximum discharging lower limit voltage. The battery is a half battery. The process that the electrode material to be tested makes the battery comprises the following steps: making electrode slurry from the electrode material to be tested; coating the electrode slurry on a current collector to make a pole piece; assembling the pole piece cut to a preset size to make the battery. The method comprises the following steps: an obtaining module is configured to obtain the target charging and discharging voltage range of the battery made of the electrode material to be tested; wherein, the width of the target charging and discharging voltage range is greater than the width of the standard charging and discharging voltage range of the battery. A charging and discharging module is configured to perform cyclic charging and discharging on the battery within the target charging and discharging voltage range, and obtain charging and discharging data of the battery during the cyclic charging and discharging; wherein the charging and discharging data comprises a discharging capacity; An evaluation module is configured to evaluate the cyclic performance of the electrode material under test based on the charging and discharging data.

14. An electrode material performance evaluation system, characterized by, comprising a memory and a processor, wherein: the processor is configured to execute a computer program stored in the memory; the processor, when executing the computer program, implements the steps in the electrode material performance evaluation method according to any one of claims 1 to 12.

15. A computer readable storage medium having stored thereon a computer program, characterized in that, the computer program, when executed by the processor, implements the steps in the electrode material performance evaluation method according to any one of claims 1 to 12.

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