A method and system for testing stability of lithium batteries

Abstract

The present application relates to the technical field of lithium battery stability test, and discloses a kind of lithium battery stability test method and system, including obtaining cycle charge-discharge frequency, setting cycle charge-discharge frequency threshold and the comparison of both.This application compares the cycle charge-discharge frequency obtained by test with cycle charge-discharge frequency threshold, if test result is lower than cycle charge-discharge frequency threshold, it shows that battery life is insufficient, test is unqualified;If the result reaches or exceeds cycle charge-discharge frequency threshold, it shows that battery durability meets the requirements, and the test is qualified.The more cycle charge-discharge frequency, the longer battery life, the higher the quality of use.

Description

Technical Field

[0001] This invention relates to the field of lithium battery stability testing technology, specifically to a method and system for testing the stability of lithium batteries. Background Technology

[0002] Lithium-ion batteries are a type of battery that uses lithium metal or lithium alloy as the negative electrode material and a non-aqueous electrolyte solution. They are divided into two types: lithium metal batteries and lithium-ion batteries. Lithium metal batteries are primary batteries, using materials such as manganese dioxide as the positive electrode material. They release electrical energy through the oxidation reaction of metallic lithium, and have high energy density, but are not rechargeable and have high safety requirements. Lithium-ion batteries, on the other hand, are rechargeable secondary batteries. The positive electrode uses lithium cobalt oxide, lithium iron phosphate, or ternary materials (such as lithium nickel cobalt manganese oxide), and the negative electrode uses carbon-based materials such as graphite. Charge-discharge cycles are achieved through the insertion and extraction of lithium ions between the positive and negative electrodes. Their core structure includes a positive electrode, a negative electrode, a separator, and an electrolyte, and they have advantages such as high operating voltage, high energy density, and long cycle life.

[0003] Lithium-ion battery stability testing mainly includes multiple aspects such as thermal stability, electrochemical stability, mechanical stability, and safety. Different testing methods are used to evaluate the performance of lithium-ion batteries under various usage and extreme conditions. For lithium-ion batteries, assuming safety standards are met, their effective capacity is the parameter that has the greatest impact on users. This is because the size of the effective capacity and the rate of effective capacity decay affect the most basic user experience. From the user's perspective, not only is a lithium-ion battery with a large effective capacity required, but it also needs to be able to last a long time. Therefore, electrochemical stability testing of lithium-ion batteries is essential. Summary of the Invention

[0004] In view of the problems existing in the prior art, the purpose of this invention is to provide a method and system for testing the stability of lithium batteries, so as to test the effective capacity decay of lithium batteries.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for testing the stability of a lithium battery, comprising: Step 1, obtaining the initial effective capacity of the lithium battery, wherein the effective capacity of the lithium battery decreasing from the initial effective capacity to the initial critical value is recorded as the critical effective capacity, and the number of charge-discharge cycles of the lithium battery is obtained when the effective capacity decreases from the initial effective capacity to the critical effective capacity; Step 2, setting a charge-discharge cycle threshold for the number of charge-discharge cycles when the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity according to parameter information and manufacturer's instructions, wherein the charge-discharge cycle threshold is the number of charge-discharge cycles when the effective capacity decreases from the initial effective capacity to the critical effective capacity. Step 3: Compare the number of charge / discharge cycles with the threshold number of charge / discharge cycles. If the number of charge / discharge cycles of the lithium battery is less than the threshold number, it means that when the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity, the number of charge / discharge cycles it can support does not reach the normal number. In this case, the lithium battery test is unqualified. If the number of charge / discharge cycles of the lithium battery is greater than or equal to the threshold number, it means that when the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity, the number of charge / discharge cycles it can support can reach or exceed the normal number. In this case, the lithium battery test is qualified.

[0006] In some implementations, a second threshold for the number of charge-discharge cycles is set. If the second threshold for the number of charge-discharge cycles is less than the first threshold for the number of charge-discharge cycles, when the number of charge-discharge cycles of the lithium battery is less than the first threshold for the number of charge-discharge cycles, the number of charge-discharge cycles is compared with the second threshold for the number of charge-discharge cycles, and different responses are given based on the comparison results.

[0007] In some implementations, if the number of charge-discharge cycles of the lithium battery is greater than or equal to the second threshold number of charge-discharge cycles, it indicates that when the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity, the number of charge-discharge cycles that the lithium battery can support is less than the normal number of cycles. In this case, the lithium battery is further tested. If the number of charge-discharge cycles of the lithium battery is less than the second threshold number of charge-discharge cycles, it indicates that when the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity, the number of charge-discharge cycles that the lithium battery can support is more than the normal number of cycles. In this case, the lithium battery test remains unqualified.

[0008] In some implementations, further testing involves obtaining the industry average standard effective capacity range, comparing the standard effective capacity range with the critical effective capacity, and determining different responses based on the comparison results.

[0009] In some implementations, if the critical effective capacity of the lithium battery is greater than the maximum value of the standard effective capacity range, it means that when the effective capacity of the lithium battery drops to the critical effective capacity, the remaining effective capacity is greater than the industry standard effective capacity. In this case, the test is qualified. If the critical effective capacity of the lithium battery is not greater than the maximum value of the standard effective capacity range, it means that when the effective capacity of the lithium battery drops to the critical effective capacity, the remaining effective capacity is not greater than the industry standard effective capacity. In this case, the test is unqualified.

[0010] In some implementations, when the critical effective capacity of the lithium battery is not greater than the maximum value of the standard effective capacity range and falls within the standard effective capacity range, the initial effective capacity to the critical effective capacity is divided into a first interval and a second interval in descending order, the number of charge-discharge cycles experienced by the first interval and the second interval are obtained, and the two are compared, and different responses are made according to the comparison results.

[0011] In some implementations, if the number of charge-discharge cycles experienced in the first interval is greater than or equal to the number of charge-discharge cycles experienced in the second interval, it means that the rate of decrease in the effective capacity of the lithium battery is accelerating. In this case, the lithium battery test is unqualified. If the number of charge-discharge cycles experienced in the first interval is less than the number of charge-discharge cycles experienced in the second interval, the difference between the two is further compared.

[0012] In some implementations, if the difference between the number of charge-discharge cycles experienced in the first interval and the number of charge-discharge cycles experienced in the second interval is more than 10%, it means that the effective capacity of the lithium battery is decreasing at a slower rate, and in this case, the lithium battery test is qualified.

[0013] This invention also provides the following technical solutions:

[0014] This invention further provides a lithium battery stability testing system for performing the above-described method, comprising: an acquisition module for acquiring the initial effective capacity of the lithium battery, wherein the effective capacity of the lithium battery decreasing from the initial effective capacity to an initial critical value is recorded as the critical effective capacity, and the number of charge-discharge cycles of the lithium battery is acquired when the effective capacity decreases from the initial effective capacity to the critical effective capacity; and a setting module for setting a charge-discharge cycle threshold for the number of charge-discharge cycles when the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity, based on parameter information and manufacturer's instructions, wherein the charge-discharge cycle threshold is the number of charge-discharge cycles when the effective capacity decreases from the initial effective capacity to the critical effective capacity. The normal number of charge-discharge cycles is measured by a comparison module, which compares the number of charge-discharge cycles with a threshold. If the number of charge-discharge cycles is less than the threshold, it means that the effective capacity of the lithium battery cannot support the normal number of charge-discharge cycles when it decreases from the initial effective capacity to the critical effective capacity. In this case, the lithium battery test is unqualified. If the number of charge-discharge cycles is greater than or equal to the threshold, it means that the effective capacity of the lithium battery can support the normal number of charge-discharge cycles when it decreases from the initial effective capacity to the critical effective capacity. In this case, the lithium battery test is qualified.

[0015] The present invention further provides a computer-readable storage medium storing a computer program, which is executed by a processor to implement the above-described method for testing the stability of a lithium battery.

[0016] The technical solution provided by this invention has the following advantages compared with the prior art:

[0017] Firstly, in this invention, the number of charge-discharge cycles obtained from the test is compared with a threshold number of charge-discharge cycles. If the test result is lower than the threshold number of charge-discharge cycles, it indicates that the battery life is insufficient and the test is unqualified; if the result reaches or exceeds the threshold number of charge-discharge cycles, it indicates that the battery durability meets the requirements and the test is qualified. The more charge-discharge cycles, the longer the battery life and the higher the quality of use.

[0018] Secondly, this invention sets a second threshold for the number of charge-discharge cycles and, by comparing the critical effective capacity of the lithium battery with the industry standard effective capacity range, can more accurately assess the stability and practical value of the lithium battery. When the number of charge-discharge cycles of the lithium battery is slightly lower than the normal number, its durability in practical applications can be determined by further evaluating its critical effective capacity. If the critical effective capacity of the lithium battery is higher than the industry standard, even if the number of charge-discharge cycles is slightly lower, it can still guarantee a longer service life. In this case, the lithium battery can still meet the user's needs, and the test result can be considered qualified. Compared to simply relying on the number of charge-discharge cycles, this method considers the absolute size of the lithium battery capacity, which is more in line with actual usage scenarios and avoids overly strict judgment standards. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the method steps of the present invention;

[0020] Figure 2 This is a schematic diagram of the module structure of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0023] The lithium battery stability testing method provided by this invention, such as... Figure 1 and Figure 2 As shown, it includes:

[0024] The first step is to obtain the initial effective capacity of the lithium battery under test using its parameter information. The effective capacity at which the lithium battery decreases from its initial effective capacity to a first critical value is defined as the critical effective capacity. This critical effective capacity is a standard indicating a significant decrease in the effective capacity of the lithium battery; for example, if the effective capacity decreases from 100% to 80%, 80% represents the critical effective capacity. Under these conditions, the lithium battery under test is subjected to charge-discharge cycles. During these cycles, the lithium battery is kept at the same temperature, voltage, and current to avoid additional variables affecting the number of cycles. When the effective capacity of the lithium battery decreases from its initial effective capacity to the critical effective capacity, the number of charge-discharge cycles is recorded and used as a basis for subsequent judgment.

[0025] The second step is to set a charge-discharge cycle threshold for the number of charge-discharge cycles required to reduce the effective capacity of a lithium battery from its initial effective capacity to its critical effective capacity. This charge-discharge cycle threshold represents the theoretically normal number of charge-discharge cycles required for a lithium battery to reduce its effective capacity from its initial effective capacity to its critical effective capacity. To obtain a practical charge-discharge cycle threshold for lithium batteries, it is necessary to simulate the battery's charge-discharge behavior under real-world usage conditions during testing. This includes repeatedly performing charge-discharge cycles within different temperature, charge-discharge current, and voltage ranges, recording the battery's capacity decay, and thus determining the number of charge-discharge cycles the lithium battery can support when it reaches a certain capacity decay level. This allows for the determination of a reasonable charge-discharge cycle threshold.

[0026] The third step is to compare the lithium battery's cycle count with the cycle count threshold and determine different responses based on the comparison results. If the lithium battery's cycle count is less than the threshold, it means that the effective capacity of the lithium battery cannot support the normal number of cycle counts when it decreases from the initial effective capacity to the critical effective capacity. In this case, the lithium battery test is unqualified. If the lithium battery's cycle count is greater than or equal to the threshold, it means that the effective capacity of the lithium battery can support the normal number of cycle counts when it decreases from the initial effective capacity to the critical effective capacity. In this case, the lithium battery test is qualified. This is because the cycle count essentially represents the durability of the lithium battery. Before the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity, the more cycle counts the user can use the battery for. For example, suppose the standard cycle count for a lithium battery to decrease from the initial effective capacity to the critical effective capacity is 500 cycles. If the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity in the process of use, it means that the cycle count is below normal. This directly impacts the user experience. If the effective capacity of a lithium battery only decreases from its initial effective capacity to its critical effective capacity after 600 charge-discharge cycles, it indicates that the number of charge-discharge cycles is higher than normal. This means the user experience exceeds expectations, resulting in a higher quality of use. Therefore, in this application, lithium battery stability testing primarily assesses battery durability and capacity decay through cyclic charge-discharge experiments. First, the initial effective capacity of the battery is obtained, and a critical effective capacity is set when the capacity drops to a certain percentage (e.g., 80%). Then, the battery is cyclically charged and discharged under constant temperature, voltage, and current conditions, and the number of charge-discharge cycles when the effective capacity drops to the critical effective capacity is recorded. Second, the battery's usage under different operating conditions is simulated experimentally to determine a reasonable threshold for the number of charge-discharge cycles. This threshold represents the theoretically expected normal cycle life of the battery. Finally, the number of charge-discharge cycles obtained from the test is compared with the threshold. If the test result is lower than the threshold, it indicates insufficient battery life, and the test is unqualified; if the result reaches or exceeds the threshold, it indicates that the battery durability meets the requirements, and the test is qualified. The more charge-discharge cycles a battery can withstand, the longer its lifespan and the higher its quality. For example, if the standard charge-discharge cycle threshold is 500 cycles, but the battery only supports 300 cycles, it indicates poor durability and affects the user experience; if it can reach 600 cycles, it indicates excellent battery quality and a lifespan exceeding expectations.

[0027] When the number of charge-discharge cycles is less than the threshold value, a second threshold value is set, which is slightly smaller than the threshold value (e.g., if the threshold value is 500 cycles, the second threshold value is 450 cycles). Based on this, the number of charge-discharge cycles of the lithium battery is compared with the second threshold value, and different responses are made according to the comparison results. If the number of charge-discharge cycles of the lithium battery is greater than or equal to the second threshold value, it indicates that when the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity, the number of charge-discharge cycles that the lithium battery can support is less than the normal number. In this case, the lithium battery is further tested. During further testing, the average standard effective capacity range of lithium batteries in the industry is obtained based on the lithium battery parameter information and the application industry. The standard effective capacity range is compared with the critical effective capacity of the lithium battery, and different responses are made according to the comparison results. If the critical effective capacity of a lithium battery is greater than the maximum value of the standard effective capacity range, it means the critical capacity exceeds the industry standard. Users will experience a longer usage time with such a battery compared to standard lithium batteries. Even if the number of charge-discharge cycles is lower than normal, the impact is insignificant due to the small difference. Furthermore, the battery's inherent effective capacity is large, so even with a slightly lower number of cycles, the remaining effective capacity at the critical effective capacity is still greater than the industry standard. Therefore, the usage time is still longer compared to the industry standard, and in this case, the lithium battery's stability test is passed. If the critical effective capacity of a lithium battery is not greater than the maximum value of the standard effective capacity range (i.e., falls within the standard effective capacity range or is less than the minimum value), it means the critical effective capacity does not exceed the industry standard. In this case, even if the number of charge-discharge cycles is lower than normal, the user will not experience more usage time because the remaining effective capacity is not significantly increased. Therefore, the lithium battery's stability test is failed. If the number of charge-discharge cycles of a lithium battery is less than the second threshold, it indicates that the effective capacity of the lithium battery has decreased significantly from its initial effective capacity to its critical effective capacity, meaning the number of charge-discharge cycles it can support is far below the normal range. In this case, the lithium battery test is considered unqualified. This method of judging the stability of a lithium battery is based on the fact that the number of charge-discharge cycles is far below the threshold, and then judges the critical effective capacity of the lithium battery within the industry's standard effective capacity range.Because if the critical effective capacity of a lithium battery exceeds the industry's standard effective capacity range, it means that the lithium battery has a larger effective capacity than conventional lithium batteries in the industry. During normal use, it will have a longer usage time than conventional lithium batteries in the industry. Even if the effective capacity drops to the critical effective capacity, the remaining effective capacity is still larger than the standard effective capacity, and the usage time remains longer. The longer usage time can compensate for the deficiency of the number of charge-discharge cycles being lower than the normal number. For example, assume that the initial effective capacity of a lithium battery is 10,000 mAh, the industry's standard effective capacity range is 5,000 - 6,000 mAh, the critical effective capacity is 8,000 mAh, the charge-discharge cycle threshold is 500 times, and the second charge-discharge cycle threshold is 450 times. When the effective capacity of the lithium battery drops from the initial effective capacity of 10,000 mAh to the critical effective capacity of 8,000 mAh, assume that the number of charge-discharge cycles of the lithium battery is 480 times, which is lower than the charge-discharge cycle threshold, but because the critical effective capacity of 8,000 mAh is greater than the standard effective capacity range of 5,000 - 6,000 mAh, the lithium battery will still have a longer usage time. Therefore, the slightly lower number of charge-discharge cycles can be ignored. This method can more accurately evaluate the stability and practical use value of lithium batteries by setting the second charge-discharge cycle threshold and combining the comparison of the critical effective capacity of the lithium battery with the industry's standard effective capacity range. When the number of charge-discharge cycles of a lithium battery is slightly lower than the normal number, by further evaluating its critical effective capacity, its durability in actual applications can be judged. If the critical effective capacity of a lithium battery is higher than the industry standard, even if the number of charge-discharge cycles is slightly lower, it can still ensure a relatively long usage time. In this case, the lithium battery can still meet user requirements, and the test results can be considered qualified. Compared with simply relying on the number of charge-discharge cycles, this method takes into account the absolute size of the lithium battery capacity, is more in line with the actual usage scenario, and avoids overly strict judgment criteria. Through this comprehensive evaluation, not only can the performance of lithium batteries be evaluated when the number of charge-discharge cycles is low, but it can also more flexibly meet the needs of different application fields, ensure that the stability test of lithium batteries is more scientific and reasonable, and help improve the reliability of lithium batteries and the user experience.

[0028] When the number of charge-discharge cycles of a lithium battery is less than the first threshold but greater than or equal to the second threshold, and the critical effective capacity falls within the standard effective capacity range, the interval between the initial effective capacity and the critical effective capacity is divided into two intervals: a first interval and a second interval. The effective capacity of the first interval is greater than that of the second interval. When the effective capacity of the lithium battery decreases to the critical effective capacity, the number of charge-discharge cycles experienced in each interval is obtained. The number of charge-discharge cycles experienced in the first interval is compared with that in the second interval, and different responses are given based on the comparison results. If the number of charge-discharge cycles experienced in the first interval is greater than or equal to that in the second interval, it means that the rate of decrease in the effective capacity of the lithium battery is accelerating, and in this case, the lithium battery test is unqualified. If the number of charge-discharge cycles experienced in the first interval is less than that in the second interval, and the difference is more than 10%, it means that the rate of decrease in the effective capacity of the lithium battery is slowing down, and in this case, the lithium battery test is qualified. In the previous method, when the number of charge-discharge cycles of the lithium battery was slightly lower than the normal number, the critical effective capacity of the lithium battery was considered. When the critical effective capacity was greater than the maximum value of the standard effective capacity range, even though the lithium battery had reached the critical effective capacity, the remaining effective capacity was still greater than the standard effective capacity, and it still had a longer usage time. Therefore, in this case, the lithium battery was considered to have passed the test. This method ignores the case where the critical effective capacity is less than or equal to the maximum value of the standard effective capacity range because in this case, the remaining effective capacity of the lithium battery is not greater than the standard effective capacity. However, when the critical effective capacity is less than the maximum value of the standard effective capacity range, there are two situations: one is that the critical effective capacity falls within the standard effective capacity range; the other is that the critical effective capacity is less than the minimum value of the standard effective capacity range. In the case where the critical effective capacity is less than the minimum value of the standard effective capacity range, the critical effective capacity means that not only is the remaining effective capacity less than the standard effective capacity, but the number of charge-discharge cycles is also lower than the normal number of cycles, so the test is considered to have failed. However, when the critical effective capacity falls within the standard effective capacity range, although the number of charge-discharge cycles is slightly lower than the normal number, the remaining effective capacity is basically the same as the standard effective capacity. Therefore, it is unreasonable to directly determine that the test is unqualified. So, an additional judgment is made here, dividing the interval between the critical effective capacity and the initial effective capacity into two intervals: the first interval is the effective capacity from 100% to 90%, and the second interval is 90% to 80%.Judge the number of charge-discharge cycles in two intervals respectively, compare the difference in the number of charge-discharge cycles between the two intervals. If the number of charge-discharge cycles experienced in the first interval is significantly less than that in the second interval, it indicates that during the reduction of the effective capacity of the lithium battery, the reduction rate is slowing down. Because the effective capacity in the second interval decreases from 90% to 80% supports more charge-discharge cycles than the effective capacity in the first interval decreases from 100% to 90%. In this case, even if the number of charge-discharge cycles of the lithium battery is slightly lower than the normal number and the critical effective capacity is basically the same as the standard effective capacity, the lithium battery test is determined to be qualified. This method further improves the accuracy and flexibility of the battery stability test by dividing the effective capacity interval of the lithium battery into the first interval and the second interval and comparing the number of charge-discharge cycles in these two intervals respectively. First, when the number of charge-discharge cycles of the lithium battery is slightly lower than the normal number but still greater than or equal to the second threshold of the number of charge-discharge cycles, and the critical effective capacity falls within the standard effective capacity range, the interval between the initial effective capacity and the critical effective capacity is divided into two parts. This division can more carefully analyze the attenuation of the battery in different capacity intervals, so as to more scientifically judge the performance of the battery. If the number of charge-discharge cycles experienced in the first interval (higher capacity interval) is significantly less than that in the second interval (lower capacity interval) and the difference exceeds 10%, it indicates that during the capacity attenuation of the lithium battery, the reduction rate of its effective capacity is slowing down, indicating that the lithium battery performs more stably in the later stage of attenuation. In this case, it can be considered that the lithium battery still has good stability and an acceptable service life, so it is determined to be qualified. In contrast, if the number of charge-discharge cycles in the first interval is more than that in the second interval, it indicates that the attenuation rate of the lithium battery is faster in the low-capacity stage, resulting in an accelerated attenuation rate of the lithium battery, thus affecting its service life. In this case, it is judged as unqualified. In addition, this method also takes into account the relationship between the critical effective capacity and the industry standard effective capacity. When the critical effective capacity falls within the standard effective capacity range, although the number of charge-discharge cycles is slightly lower than the normal number, because the remaining effective capacity is close to the standard effective capacity, the user's usage time is basically the same as the industry standard. Therefore, it cannot be directly determined as unqualified, which increases the rationality and tolerance of the test. Generally speaking, this method makes the test results more in line with the actual usage requirements by carefully analyzing the battery attenuation rate and comprehensively considering the change of the effective capacity, improves the scientificity and flexibility of judging the stability of the lithium battery, and at the same time avoids unreasonable judgments caused by overly strict standards.

[0029] The processes described above with reference to the flowcharts in the embodiments disclosed in this invention can be implemented as computer software programs. Embodiments of this invention include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication component, and / or installed from a removable medium. When the computer program is executed by a central processing unit, it performs the functions defined in the methods of this application. It should be noted that the computer-readable medium described above in this application can be a computer-readable signal medium or a computer-readable storage medium, or any combination of the two. A computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection having one or more wire segments, a portable computer disk, a hard disk, a random access memory, a read-only memory, an erasable programmable read-only memory, an optical fiber, a portable compact disk read-only memory, an optical storage device, a magnetic storage device, or any suitable combination thereof. In this application, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in connection with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium can also be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wireless segments, wire segments, optical cables, RF, etc., or any suitable combination thereof.

[0030] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0031] Those skilled in the art should understand that the above description is only a specific embodiment of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application.

Claims

1. A method for testing the stability of lithium batteries, characterized in that, include: Step 1: Obtain the initial effective capacity of the lithium battery. The effective capacity of the lithium battery when it decreases from the initial effective capacity to the initial critical value is recorded as the critical effective capacity. When the effective capacity decreases from the initial effective capacity to the critical effective capacity, obtain the number of charge-discharge cycles of the lithium battery. Step 2: Based on the parameter information and manufacturer's instructions, set the cycle charge / discharge number threshold when the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity. The cycle charge / discharge number threshold is the normal number of cycle charge / discharge cycles when the effective capacity decreases from the initial effective capacity to the critical effective capacity. Step 3: Compare the number of charge-discharge cycles with the charge-discharge cycle threshold. If the number of charge-discharge cycles of the lithium battery is less than the charge-discharge cycle threshold, it means that when the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity, the number of charge-discharge cycles it can support does not reach the normal number of cycles. In this case, the lithium battery test is unqualified. If the number of charge-discharge cycles of a lithium battery is greater than or equal to the threshold number of charge-discharge cycles, it means that when the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity, the number of charge-discharge cycles it can support can reach or exceed the normal number of cycles. In this case, the lithium battery test is qualified. A second threshold number of charge-discharge cycles is set. If the number of charge-discharge cycles of the lithium battery is less than the first threshold number, the number of charge-discharge cycles is compared with the second threshold number, and different actions are taken based on the comparison result. If the number of charge-discharge cycles of the lithium battery is greater than or equal to the second threshold number, it means that when the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity, the degree to which the number of charge-discharge cycles the lithium battery can support is lower than the normal number of cycles. In this case, the lithium battery is further tested. If the number of charge-discharge cycles of the lithium battery is less than the second threshold number, it means that when the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity, the number of charge-discharge cycles the lithium battery can support is less than the normal number of cycles. In this case, the lithium battery is further tested. If the number of charge-discharge cycles is less than the second threshold, it indicates that the effective capacity of the lithium battery has decreased significantly from its initial effective capacity to its critical effective capacity, meaning the number of charge-discharge cycles it can support is far below the normal range. In this case, the lithium battery test remains unqualified. Further testing involves obtaining the industry average standard effective capacity range and comparing it with the critical effective capacity. Different responses are then determined based on the comparison results. If the critical effective capacity of the lithium battery is greater than the maximum value of the standard effective capacity range, it means that when the effective capacity of the lithium battery decreases to the critical effective capacity, the remaining effective capacity is greater than the industry standard effective capacity. In this case, the test is qualified. If the critical effective capacity of the lithium battery is not greater than the maximum value of the standard effective capacity range, it means that when the effective capacity of the lithium battery decreases to the critical effective capacity, the remaining effective capacity is not greater than the industry standard effective capacity. In this case, the test fails.

2. The method for testing the stability of lithium batteries according to claim 1, characterized in that, When the critical effective capacity of a lithium battery is not greater than the maximum value of the standard effective capacity range and falls within the standard effective capacity range, the initial effective capacity to the critical effective capacity is divided into a first interval and a second interval in descending order. The number of charge-discharge cycles experienced by the first interval and the second interval are obtained and compared. Different responses are made based on the comparison results.

3. The method for testing the stability of lithium batteries according to claim 2, characterized in that, If the number of charge-discharge cycles in the first interval is greater than or equal to the number of charge-discharge cycles in the second interval, it means that the effective capacity of the lithium battery is decreasing at an accelerated rate. In this case, the lithium battery test is unqualified. If the number of charge-discharge cycles in the first interval is less than the number of charge-discharge cycles in the second interval, the difference between the two should be further compared.

4. The method for testing the stability of lithium batteries according to claim 3, characterized in that, If the number of charge-discharge cycles experienced in the first interval is more than 10% less than the number of charge-discharge cycles experienced in the second interval, it means that the effective capacity of the lithium battery is decreasing at a slower rate. In this case, the lithium battery test is qualified.

5. A lithium battery stability testing system, used to perform the method according to any one of claims 1-4, characterized in that, include: The acquisition module is used to acquire the initial effective capacity of the lithium battery. The effective capacity of the lithium battery when the initial effective capacity decreases to the initial critical value is recorded as the critical effective capacity. When the effective capacity decreases from the initial effective capacity to the critical effective capacity, the number of charge-discharge cycles of the lithium battery is acquired. The setting module is used to set the cycle charge and discharge number threshold when the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity, based on parameter information and manufacturer instructions. The cycle charge and discharge number threshold is the normal number of cycle charge and discharge times when the effective capacity decreases from the initial effective capacity to the critical effective capacity. The comparison module is used to compare the number of charge-discharge cycles with the charge-discharge cycle threshold. If the number of charge-discharge cycles of the lithium battery is less than the charge-discharge cycle threshold, it means that when the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity, the number of charge-discharge cycles it can support does not reach the normal number of cycles. In this case, the lithium battery test is unqualified. If the number of charge-discharge cycles of a lithium battery is greater than or equal to the threshold number of charge-discharge cycles, it means that when the effective capacity of the lithium battery decreases from the initial effective capacity to the critical effective capacity, the number of charge-discharge cycles it can support can reach or exceed the normal number of cycles. In this case, the lithium battery test is qualified.

6. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that is executed by a processor to implement a method for testing the stability of a lithium battery as described in any one of claims 1-4.

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