Method for testing cycle performance of lithium ion battery

Abstract

The invention provides a lithium ion battery cycle performance test method, which comprises the following steps: acquiring a plurality of lithium ion batteries to be tested, and dividing the plurality of lithium ion batteries to be tested into a reference group and a high-temperature high-rate group; carrying out constant-rate charge-discharge cycle test on the to-be-tested lithium ion battery of the reference group at a first temperature and a first rate, and circulating for a first set number of turns to obtain a capacity attenuation rate of the reference group; carrying out constant-rate charge-discharge cycle test on the high-temperature high-rate group at a second temperature at a first set capacity retention ratio and at a second rate until the capacity retention ratio reaches the first set capacity retention ratio, so as to obtain the capacity fading rate of the high-temperature high-rate group; comparing the capacity attenuation rate of the reference group with the capacity attenuation rate of the high-temperature high-rate group, and determining the cycle performance of the lithium ion battery to be tested based on a comparison result; the second temperature is higher than the first temperature, and the second magnification is higher than the first magnification. According to the invention, the battery cycle performance test time can be saved, and the test purpose is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery performance testing, and particularly relates to a method for testing the cycle performance of lithium-ion batteries. Background Art

[0002] With the development of lithium-ion batteries, the applications of lithium-ion batteries in the automotive field and the energy storage field are becoming increasingly widespread. Especially in the energy storage field, the full-life cycle cycle requirements for energy storage systems have been increased from several thousand cycles at the beginning to 8,000 cycles or even 12,000 - 15,000 cycles. However, for the testing of long-cycle electric cores, the commonly used method is the long-time cycle testing method under actual working conditions. Although this method can relatively accurately evaluate the cycle performance of the electric core, it has obvious defects and deficiencies. First, the testing time is too long. After the product is developed, the actual testing time may need to be calculated in years, which not only prolongs the R & D cycle but also increases time and costs. Second, the long-time testing requires a large amount of equipment investment and maintenance costs. Finally, due to the long testing time, it may be affected by various uncertain factors, resulting in a reduction in the reliability of the test results. Summary of the Invention

[0003] Embodiments of the present invention provide a method for testing the cycle performance of lithium-ion batteries, which can improve the technical problem that the existing battery cycle performance testing time is too long.

[0004] In a first aspect, embodiments of the present invention provide a method for testing the cycle performance of lithium-ion batteries, including:

[0005] Obtain a plurality of lithium-ion batteries to be tested, and divide the plurality of lithium-ion batteries to be tested into a reference group and a high-temperature high-rate group;

[0006] Perform a constant-rate charge and discharge cycle test on the lithium-ion batteries to be tested in the reference group at a first temperature and at a first rate for a first set number of cycles to obtain the capacity attenuation rate of the reference group;

[0007] Perform a constant-rate charge and discharge cycle test on the lithium-ion batteries in the high-temperature high-rate group at a second temperature and at a second rate until the capacity retention rate reaches a first set capacity retention rate to obtain the capacity attenuation rate of the high-temperature high-rate group;

[0008] Compare the capacity attenuation rate of the reference group with the capacity attenuation rate of the high-temperature high-rate group, and determine the cycle performance of the lithium-ion batteries to be tested based on the comparison result;

[0009] The second temperature is higher than the first temperature, and the second rate is higher than the first rate.

[0010] In one embodiment, the first temperature is 20°C - 30°C, the first rate is 0.25C - 0.65C, and the first set number of cycles is 2,000 cycles - 3,000 cycles; and / or

[0011] The second temperature is 35°C - 50°C, the second rate is 0.8C - 1.2C, and the first set capacity retention rate is 70% - 80%.

[0012] In one embodiment, after the capacity retention rate of the high-temperature high-rate group reaches the first set capacity retention rate, the lithium-ion battery cycle performance test method further includes:

[0013] Continuing to perform a constant-rate charge and discharge cycle test on the lithium-ion battery to be tested in the high-temperature high-rate group at a third temperature and at a third rate until the capacity retention rate reaches the second set capacity retention rate, so as to obtain the capacity attenuation rate of the high-temperature high-rate group;

[0014] The second temperature is higher than the third temperature, and the second rate is higher than the third rate.

[0015] In one embodiment, the third temperature is 20°C - 35°C, the third rate is 0.5C - 0.8C, and the second set capacity retention rate is 60% - 70%.

[0016] In one embodiment, after the capacity retention rate of the high-temperature high-rate group reaches the second set capacity retention rate, the lithium-ion battery cycle performance test method further includes:

[0017] Continuing to perform a constant-rate charge and discharge cycle test on the lithium-ion battery to be tested in the high-temperature high-rate group at the third temperature and at a fourth rate until the capacity retention rate is 60%, so as to obtain the capacity attenuation rate of the high-temperature high-rate group;

[0018] The fourth rate is less than the third rate.

[0019] In one embodiment, the lithium-ion battery cycle performance test method further includes:

[0020] Multiple lithium-ion batteries to be tested are further divided into a high-temperature group, and the high-temperature group is subjected to a constant-rate charge and discharge cycle test at a second temperature and at a first rate until the capacity retention rate reaches the first set capacity retention rate, so as to obtain the capacity attenuation rate of the high-temperature group;

[0021] Comparing the capacity attenuation rate of the reference group and the capacity attenuation rate of the high-temperature group, and determining the high-temperature performance of the lithium-ion battery to be tested based on the comparison result.

[0022] In one embodiment, after the capacity retention rate of the high-temperature group reaches the first set capacity retention rate, the lithium-ion battery cycle performance test method further includes:

[0023] Continuing to perform a constant-rate charge and discharge cycle test on the lithium-ion battery to be tested in the high-temperature group at the third temperature and at the first rate until the capacity retention rate reaches the second set capacity retention rate, so as to obtain the capacity attenuation rate of the high-temperature group.

[0024] In one embodiment, the method for testing the cycle performance of a lithium-ion battery further includes:

[0025] The multiple lithium-ion batteries to be tested are further divided into a high-rate group. The lithium-ion batteries to be tested in the high-rate group are subjected to a constant-rate charge-discharge cycle test at a second rate at a first temperature until the capacity retention rate reaches a first set capacity retention rate, and the capacity attenuation rate of the high-rate group is obtained.

[0026] Compare the capacity attenuation rate of the reference group with that of the high-rate group, and determine the rate performance of the lithium-ion batteries to be tested based on the comparison result.

[0027] In one embodiment, when the capacity retention rate of the high-rate group reaches the first set capacity retention rate, the method for testing the cycle performance of a lithium-ion battery further includes:

[0028] The lithium-ion batteries to be tested in the high-rate group continue to be subjected to a constant-rate charge-discharge cycle test at a third rate at a third temperature until the capacity retention rate reaches a second set capacity retention rate, and the capacity attenuation rate of the high-rate group is obtained.

[0029] In one embodiment, the charge-discharge depth of the constant-rate charge-discharge cycle test for the reference group, the high-temperature group, the high-rate group, and the high-temperature high-rate group is 100%.

[0030] In the embodiments of the present invention, by subjecting the lithium-ion batteries to be tested in the reference group to a constant-rate charge-discharge cycle test in a standard mode at a first temperature and a first rate, and subjecting the lithium-ion batteries to be tested in the high-temperature high-rate group to a constant-rate charge-discharge cycle test in a high-temperature and high-rate mode at a second temperature higher than the first temperature and a second rate greater than the first rate, the aging of the battery can be accelerated and the test time can be shortened. Then, by comparing the capacity attenuation rate of the reference group with that of the high-temperature high-rate group, the cycle performance of the lithium-ion batteries to be tested is determined based on the comparison result. Generally, if the two are similar, it proves that the cycle performance of the lithium-ion batteries to be tested can meet the requirements. This method can save the cycle performance test time and achieve the purpose of the cycle performance test. Detailed implementation manners

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention. In addition, it should be understood that the specific implementation manners described here are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0032] The technical solutions of the present application are as follows:

[0033] In a first aspect, an embodiment of the present application provides a method for testing the cycle performance of a lithium-ion battery, including:

[0034] Obtain a plurality of lithium-ion batteries to be tested, and divide the plurality of lithium-ion batteries to be tested into a reference group and a high-temperature high-rate group;

[0035] Perform a constant-rate charge-discharge cycle test on the lithium-ion batteries to be tested in the reference group at a first temperature and at a first rate for a first set number of cycles to obtain the capacity attenuation rate of the reference group;

[0036] Perform a constant-rate charge-discharge cycle test on the lithium-ion batteries to be tested in the high-temperature high-rate group at a second temperature and at a second rate until the capacity retention rate reaches a first set capacity retention rate to obtain the capacity attenuation rate of the high-temperature high-rate group;

[0037] Compare the capacity attenuation rate of the reference group with the capacity attenuation rate of the high-temperature high-rate group, and determine the cycle performance of the lithium-ion batteries to be tested based on the comparison result;

[0038] The second temperature is higher than the first temperature, and the second rate is higher than the first rate.

[0039] In the present application, by performing a constant-rate charge-discharge cycle test in a standard mode on the lithium-ion batteries to be tested in the reference group at a first temperature and at a first rate, and performing a constant-rate charge-discharge cycle test in a high-temperature and high-rate mode on the lithium-ion batteries to be tested in the high-temperature high-rate group at a second temperature higher than the first temperature and at a second rate greater than the first rate, the aging of the battery can be accelerated and the test time can be shortened. Then, by comparing the capacity attenuation rate of the reference group with the capacity attenuation rate of the high-temperature high-rate group and determining the cycle performance of the lithium-ion batteries to be tested based on the comparison result, generally if the two are similar (usually the difference is within 0.001%), it proves that the cycle performance of the lithium-ion batteries to be tested can meet the requirements. This method can save the cycle performance test time and achieve the purpose of the cycle performance test; if the difference between the two is large, it can prove that the cycle performance of the lithium-ion batteries to be tested does not meet the standard, that is, when the lithium-ion batteries to be tested are cycled to the first set capacity retention rate, a diving phenomenon may occur.

[0040] It can be understood that the rate (P) represents the amount of electricity charged and discharged by the battery within a specified time. 0.5P means that the battery is charged and discharged at 0.5 times the rated capacity. The capacity retention rate refers to the percentage of the capacity when the battery is fully charged to the rated capacity after the battery has been used for a period of time. The attenuation rate refers to the amount of attenuation of the battery capacity within a certain number of cycles, such as the amount of capacity attenuation per 1000 cycles. The standard charge and discharge cycle test method for lithium-ion batteries is: perform charge and discharge cycle tests at a constant rate of 0.25P - 0.65P at 20 - 30°C until the capacity retention rate reaches 60% - 70% (which can reach 12,000 - 15,000 cycles). Cycling in this way takes 8 - 16 years. The capacity attenuation rates of the lithium-ion batteries to be tested before the battery dives (the phenomenon of a sharp acceleration in capacity attenuation) are basically the same (the data line of the capacity retention rate is close to a straight line, and the slope of the straight line is the capacity attenuation rate). Therefore, if the capacity attenuation rate of the lithium-ion batteries to be tested in the high-temperature and high-rate group cycled under high-temperature and high-rate conditions is similar to the capacity attenuation rate of the lithium-ion batteries to be tested in the reference group, it proves that the reference group can be cycled to the first set capacity retention rate without diving, that is, it can meet the cycle performance test standard. To improve the accuracy of the lithium-ion battery cycle performance test results, the number of lithium-ion batteries to be tested in each group can be multiple, and the cycle performance of the lithium-ion batteries to be tested can be judged by the method of all passing or controlling the passing ratio.

[0041] In some embodiments, the first temperature is 20°C - 30°C, for example, it can be 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, etc., the first rate is 0.25P - 0.65P, for example, it can be 0.25P, 0.30P, 0.35P, 0.40P, 0.45P, 0.50P, 0.55P, 0.60P, 0.65P, etc., and the first set number of cycles is 2000 - 3000 cycles, for example, it can be 2000 cycles, 2100 cycles, 2200 cycles, 2300 cycles, 2400 cycles, 2500 cycles, 2600 cycles, 2700 cycles, 2800 cycles, 2900 cycles, 3000 cycles, etc.

[0042] In this application, the reference group is charged and discharged in a cycle of 20°C - 30°C and 0.25P - 0.65P for 2000 - 3000 cycles, that is, the standard test method. The capacity attenuation rate of the lithium-ion batteries to be tested measured by the reference group is used as the capacity attenuation rate standard, which can be used to judge whether the capacity attenuation rate of the lithium-ion batteries to be tested in other groups meets the standard.

[0043] In some embodiments, the second temperature is 35°C - 50°C, for example, it can be 35°C, 37°C, 39°C, 41°C, 43°C, 45°C, 47°C, 49°C, 50°C, etc., the second rate is 0.8P - 1.2P, for example, it can be 0.8P, 0.85P, 0.9P, 0.95P, 1.0P, 1.05P, 1.10P, 1.15P, 1.2P, etc., and the first set capacity retention rate is 70% - 80%, for example, it can be 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, etc.

[0044] In this application, the lithium-ion battery to be tested in the high-temperature high-rate group is cycled at 35°C - 50°C and 0.8P - 1.2P until the capacity retention rate reaches 70% - 80%. Under the action of high temperature and high rate, the aging speed of the battery can be accelerated, thereby shortening the test time. At the same time, at this temperature and rate, the phenomenon of battery collapse caused by too high temperature and too large rate can be reduced. Cycling until the capacity retention rate reaches 70% - 80% can meet the basic performance requirements of the battery.

[0045] In some embodiments, after the capacity retention rate of the high-temperature high-rate group reaches the first set capacity retention rate, the lithium-ion battery cycle performance test method further includes:

[0046] Continuing to perform a constant-rate charge and discharge cycle test on the lithium-ion battery to be tested in the high-temperature high-rate group at the third temperature and at the third rate until the capacity retention rate reaches the second set capacity retention rate, so as to obtain the capacity attenuation rate of the high-temperature high-rate group;

[0047] The second temperature is higher than the third temperature, and the second rate is higher than the third rate.

[0048] In this application, by continuing to perform a cycle test on the lithium-ion battery to be tested in the high-temperature high-rate group at a third temperature lower than the second temperature and at a third rate lower than the second rate, the cycle performance of the battery can be further tested, and at the same time, the probability of the battery showing a diving phenomenon can be reduced.

[0049] In some embodiments, the third temperature is 20°C - 35°C, for example, it can be 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, etc., the third rate is 0.5P - 0.8P, for example, it can be 0.5P, 0.55P, 0.6P, 0.65P, 0.7P, 0.75P, 0.8P, etc., and the second set capacity retention rate is 60% - 70%, for example, it can be 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, etc.

[0050] In this application, the lithium-ion battery to be tested in the high-temperature high-rate group is subjected to a constant-rate charge-discharge cycle test at a second temperature and a second rate to accelerate its aging. When cycling at high temperature and high rate for a long time, a diving phenomenon is likely to occur. By continuing to perform a cycle test on the lithium-ion battery to be tested in the high-temperature high-rate group at 20°C - 35°C and 0.5P - 0.8P, the diving phenomenon of the lithium-ion battery to be tested in the high-temperature high-rate group due to excessive cycling time at high temperature and high rate can be reduced. At the same time, if the lithium-ion battery to be tested in the high-temperature high-rate group does not show a diving phenomenon when the cycle reaches a capacity retention rate of 60% - 70%, it can be proved that the lithium-ion battery to be tested in the reference group can cycle to a capacity retention rate of 60% - 70% without showing a diving phenomenon, thereby improving the accuracy of the test.

[0051] In some embodiments, after the capacity retention rate of the high-temperature high-rate group reaches the second set capacity retention rate, the lithium-ion battery cycle performance test method further includes:

[0052] Continuing to perform a constant-rate charge-discharge cycle test on the lithium-ion battery to be tested in the high-temperature high-rate group at a third temperature and a fourth rate until the capacity retention rate is 60% to obtain the capacity attenuation rate of the high-temperature high-rate group;

[0053] The fourth rate is less than the third rate.

[0054] In this application, by continuing to perform a constant-rate charge-discharge cycle test on the lithium-ion battery to be tested in the high-temperature high-rate group at a fourth rate less than the third rate until the capacity retention rate is 60%, the test of the entire battery life cycle can be completed, and the accuracy of the test can be improved. If the lithium-ion battery to be tested in the high-temperature high-rate group does not show a diving phenomenon when the continuous charge-discharge cycle reaches a capacity retention rate of 60%, it proves that the cycle performance of the battery will not show a diving phenomenon in the standard test, that is, the cycle performance of the battery meets the standard.

[0055] In some embodiments, the fourth rate is 0.3P - 0.5P, for example, it can be 0.30P, 0.32P, 0.34P, 0.36P, 0.38P, 0.40P, 0.42P, 0.44P, 0.46P, 0.48P, 0.5P, etc.

[0056] In some embodiments, the lithium-ion battery cycle performance test method further includes: multiple lithium-ion batteries to be tested are also divided into a high-temperature group, and the high-temperature group is subjected to a constant-rate charge-discharge cycle test at a first rate at a second temperature until the capacity retention rate reaches the first set capacity retention rate to obtain the capacity attenuation rate of the high-temperature group;

[0057] Comparing the capacity attenuation rate of the reference group and the capacity attenuation rate of the high-temperature group, and determining the high-temperature performance of the lithium-ion battery to be tested based on the comparison result.

[0058] In this application, by setting up a high-temperature group, when the difference between the capacity attenuation rate of the high-temperature high-rate group and that of the reference group is large (for example, when the lithium-ion battery to be tested in the high-temperature high-rate group encounters a diving situation during the charge-discharge cycle test), the high-temperature performance of the battery can be judged by comparing the capacity attenuation rate of the high-temperature group and that of the reference group. If the capacity attenuation rates of the high-temperature group and the reference group are the same, it means that the high-temperature performance of the battery is good, and at the same time, it can also prove that the rate performance of the battery needs to be improved; if the capacity attenuation rates of the high-temperature group and the reference group are different (for example, when the lithium-ion battery to be tested in the high-temperature group encounters a diving situation during the charge-discharge cycle test), it means that the high-temperature performance of the battery needs to be improved.

[0059] In some embodiments, after the capacity retention rate of the high-temperature group reaches the first set capacity retention rate, the lithium-ion battery cycle performance test method further includes:

[0060] Continuing to perform a constant-rate charge-discharge cycle test on the lithium-ion battery to be tested in the high-temperature group at a first rate at a third temperature until the capacity retention rate reaches the second set capacity retention rate, so as to obtain the capacity attenuation rate of the high-temperature group.

[0061] In this application, the lithium-ion battery to be tested in the high-temperature group is subjected to a constant-rate charge-discharge cycle test at a first rate at a second temperature to accelerate its aging. Cycling at a high temperature for a long time is likely to cause a diving phenomenon. By continuing to perform a cycle test on the lithium-ion battery to be tested in the high-temperature group at a third temperature lower than the second temperature, the cycle performance of the battery can be further tested. For example, when the lithium-ion battery to be tested in the high-temperature group does not show a diving phenomenon when cycled to a capacity retention rate of 60%-70%, it can be proved that the lithium-ion battery to be tested in the reference group can be cycled to a capacity retention rate of 60%-70% without showing a diving phenomenon, thereby improving the test accuracy and at the same time reducing the probability of the battery showing a diving phenomenon due to excessive cycling time at a high temperature.

[0062] In some embodiments, after the capacity retention rate of the lithium-ion battery to be tested in the high-temperature group reaches the second set capacity retention rate, the lithium-ion battery cycle performance test method further includes: continuing to perform a constant-rate charge-discharge cycle test on the lithium-ion battery to be tested in the high-temperature group at a fourth rate at a third temperature until the capacity retention rate is 60%, so as to obtain the capacity attenuation rate of the high-temperature group;

[0063] The fourth rate is less than the third rate.

[0064] In this application, by continuously performing constant-rate charge and discharge cycling tests on the lithium-ion battery to be tested in the high-temperature group at a fourth rate less than the third rate until the capacity retention rate reaches 60%, the test of the entire battery life cycle can be completed, improving the test accuracy. If the lithium-ion battery to be tested in the high-temperature group does not show a sudden drop when continuously charged and discharged until the capacity retention rate reaches 60%, it proves that the cycling performance of the battery will not show a sudden drop in the standard test, that is, the cycling performance of the battery meets the standard.

[0065] In some embodiments, the lithium-ion battery cycling performance test method further includes: a plurality of lithium-ion batteries to be tested are also divided into a high-rate group, and the lithium-ion batteries to be tested in the high-rate group are subjected to constant-rate charge and discharge cycling tests at a second rate at a first temperature until the capacity retention rate reaches a first set capacity retention rate, obtaining the capacity attenuation rate of the high-rate group;

[0066] Compare the capacity attenuation rate of the reference group with that of the high-rate group, and determine the rate performance of the lithium-ion battery to be tested based on the comparison result.

[0067] In this application, by setting up the high-rate group, when the difference between the capacity attenuation rate of the high-temperature high-rate group and that of the reference group is large (such as the test lithium-ion battery in the high-temperature high-rate group encounters a sudden drop during the charge and discharge cycling test), the rate performance of the battery can be judged by comparing the capacity attenuation rate of the high-rate group with that of the reference group. If the capacity attenuation rates of the high-rate group and the reference group are the same, it means that the rate performance of the battery is good, and at the same time, it can also prove that the high-temperature performance of the battery needs to be improved; if the capacity attenuation rates of the high-rate group and the reference group are different (such as the high-rate group encounters a sudden drop during the charge and discharge cycling test), it means that the rate performance of the battery needs to be improved.

[0068] In some embodiments, when the capacity retention rate of the test lithium-ion battery in the high-rate group reaches the first set capacity retention rate, the lithium-ion battery cycling performance test method further includes:

[0069] Continuously perform constant-rate charge and discharge cycling tests on the test lithium-ion battery in the high-rate group at a third rate at a third temperature until the capacity retention rate reaches a second set capacity retention rate.

[0070] In this application, the test lithium-ion battery of the high magnification group is subjected to a constant magnification charge and discharge cycle test at the second temperature and the first magnification to accelerate its aging. When cycling at a high magnification for a long time, a diving phenomenon is likely to occur. By continuing the cycle test of the test lithium-ion battery of the high magnification group at the third magnification, if no diving phenomenon occurs when the high magnification group is cycled to a capacity retention rate of 60%-70%, it can be proved that the test lithium-ion battery of the reference group can be cycled to a capacity retention rate of 60%-70% without diving, thereby improving the test accuracy and reducing the probability of the battery diving due to too long a cycling time at a high magnification.

[0071] In some embodiments, after the capacity retention rate of the test lithium-ion battery of the high magnification group reaches the second set capacity retention rate, the lithium-ion battery cycle performance test method further includes:

[0072] Continuing the constant magnification charge and discharge cycle test of the test lithium-ion battery of the high magnification group at the third temperature and the fourth magnification until the capacity retention rate is 60% to obtain the high temperature group capacity attenuation rate;

[0073] The fourth magnification is less than the third magnification.

[0074] In this application, by continuing the constant magnification charge and discharge cycle test of the test lithium-ion battery of the high magnification group at a fourth magnification less than the third magnification until the capacity retention rate is 60%, the test of the entire battery life cycle can be completed and the test accuracy can be improved. If the test lithium-ion battery of the high magnification group does not show a diving phenomenon when continuously charged and discharged to a capacity retention rate of 60%, it proves that the cycle performance of the battery will not show a diving phenomenon in the standard test, that is, the cycle performance of the battery meets the standard.

[0075] In some embodiments, the depth of discharge (DOD) of the charge and discharge cycle tests of the reference group, high temperature group, high magnification group, and high temperature high magnification group is 100%. In this way, the cycle life of the battery can be better detected and the test accuracy can be improved.

[0076] It can be understood that the depth of discharge DOD (Depth of Discharge) refers to the percentage between the charge and discharge amount of the battery and the rated capacity of the battery. Generally, the deeper the depth of discharge, the shorter the cycle life of the battery.

[0077] The embodiments of the present invention have been introduced in detail above. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and core idea of the present invention; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A lithium ion battery cycle performance testing method, characterized in that: include: Acquire a plurality of lithium-ion batteries to be tested, and divide the plurality of lithium-ion batteries to be tested into a reference group and a high-temperature high-rate group; The lithium-ion battery to be tested in the reference group is subjected to a constant rate charge-discharge cycle test at a first temperature and a first rate for a first set number of cycles to obtain a capacity decay rate of the reference group; The lithium-ion battery to be tested in the high-temperature high-rate group is subjected to a constant-rate charge-discharge cycle test at a second temperature and a second rate until the capacity retention rate reaches a first set capacity retention rate, thereby obtaining a capacity attenuation rate of the high-temperature high-rate group; Comparing the capacity decay rate of the reference group with the capacity decay rate of the high-temperature and high-rate group, and determining the cycle performance of the lithium-ion battery to be tested based on the comparison result; The second temperature is higher than the first temperature, and the second ratio is higher than the first ratio.

2. The lithium ion battery cycle performance testing method according to claim 1, characterized in that: The first temperature is 20°C-30°C, the first ratio is 0.25P-0.65P, and the first set number of turns is 2000 turns-3000 turns; and / or The second temperature is 35° C.-50° C., the second ratio is 0.8P-1.2P, and the first set capacity retention rate is 70%-80%.

3. The lithium ion battery cycle performance testing method according to claim 1, characterized in that: After the capacity retention rate of the high-temperature and high-rate group reaches a first set capacity retention rate, the lithium-ion battery cycle performance testing method further includes: The lithium-ion battery to be tested in the high-temperature high-rate group continues to perform a constant-rate charge-discharge cycle test at a third temperature and a third rate until the capacity retention rate reaches a second set capacity retention rate, thereby obtaining a capacity attenuation rate of the high-temperature high-rate group; The second temperature is higher than the third temperature, and the second ratio is higher than the third ratio.

4. The lithium ion battery cycle performance testing method according to claim 3, characterized in that: The third temperature is 20° C.-35° C., the third ratio is 0.5P-0.8P, and the second set capacity retention rate is 60%-70%.

5. The lithium ion battery cycle performance testing method according to claim 3, characterized in that: After the capacity retention rate of the high-temperature and high-rate group reaches the second set capacity retention rate, the lithium-ion battery cycle performance testing method further includes: The lithium-ion battery to be tested in the high-temperature high-rate group continues to perform a constant-rate charge-discharge cycle test at the third temperature and at a fourth rate until the capacity retention rate is 60%, thereby obtaining a capacity attenuation rate of the high-temperature high-rate group; The fourth magnification is smaller than the third magnification.

6. The lithium ion battery cycle performance testing method according to claim 3, characterized in that: The lithium ion battery cycle performance testing method also includes: The plurality of lithium-ion batteries to be tested are further divided into a high-temperature group, and the lithium-ion batteries to be tested in the high-temperature group are subjected to a constant-rate charge-discharge cycle test at the first rate at the second temperature until the capacity retention rate reaches the first set capacity retention rate, thereby obtaining a capacity attenuation rate of the high-temperature group; The capacity decay rate of the reference group and the capacity decay rate of the high temperature group are compared, and the high temperature performance of the lithium ion battery to be tested is determined based on the comparison result.

7. The lithium ion battery cycle performance testing method according to claim 6, characterized in that: After the capacity retention rate of the high temperature group reaches the first set capacity retention rate, the lithium ion battery cycle performance testing method further includes: The lithium-ion battery to be tested in the high temperature group continues to be subjected to a constant rate charge and discharge cycle test at the first rate at the third temperature until the capacity retention rate reaches the second set capacity retention rate, thereby obtaining the capacity attenuation rate of the high temperature group.

8. The lithium ion battery cycle performance testing method according to claim 6, characterized in that: The lithium ion battery cycle performance testing method also includes: The plurality of lithium-ion batteries to be tested are further divided into a large rate group, and the lithium-ion batteries to be tested in the large rate group are subjected to a constant rate charge-discharge cycle test at the second rate at the first temperature until the capacity retention rate reaches the first set capacity retention rate, thereby obtaining a capacity attenuation rate of the large rate group; The capacity decay rate of the reference group and the capacity decay rate of the high-rate group are compared, and the rate performance of the lithium-ion battery to be tested is determined based on the comparison result.

9. The lithium ion battery cycle performance testing method according to claim 8, characterized in that: When the capacity retention rate of the high rate group reaches the first set capacity retention rate, the lithium ion battery cycle performance testing method further includes: The lithium-ion batteries to be tested in the high-rate group continue to undergo constant-rate charge-discharge cycle testing at the third temperature and the third rate until the capacity retention rate reaches the second set capacity retention rate, thereby obtaining the capacity attenuation rate of the high-rate group.

10. The lithium ion battery cycle performance testing method according to claim 8, characterized in that: The charge and discharge depth of the constant rate charge and discharge cycle test of the reference group, the high temperature group, the high rate group and the high temperature high rate group is 100%.