A method and system for detecting a lithium-ion battery cell

Abstract

This invention provides a method and system for testing lithium-ion battery cells. The method comprises the following steps: dividing lithium-ion battery cells into a first group and a second group; testing the performance of the first group in a first environment and testing the performance of the second group in a second environment; recording the tested performance of the first group and the second group at predetermined time intervals; and deriving the performance changes of the lithium-ion battery cells based on the tested performance of the first group and the second group.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery cells, specifically to the field of lithium-ion battery cell manufacturing verification. The invention discloses a method and system for testing lithium-ion battery cells, a computer device for implementing the method, and a computer-readable storage medium. Background Technology

[0002] Currently, with the development of new energy vehicles, lithium-ion battery cells are widely used in the power field. Common lithium-ion batteries use a liquid electrolyte system, and battery sealing is one of the important performance indicators for evaluating lithium batteries. In the field of power batteries, it is required that the battery does not leak and has good sealing throughout its entire lifespan; this is a prerequisite for ensuring cell performance and safe use.

[0003] Existing verification technologies typically test off-line battery cells. Common methods include vacuum helium (He) testing of lithium batteries before and after electrolyte filling. This involves placing unfilled cells in a container, evacuating the container, filling the cells with helium, and then testing the helium leakage rate. Alternatively, it involves placing helium-filled cells (with electrolyte and sealed) in a vacuum container, evacuating the container, and then testing the helium leakage rate. Patent CN201610564127.5 provides a helium testing method for the sealing of pouch lithium batteries, and patent CN01710125397.0 provides a helium testing system for battery covers. However, these methods only test cells during manufacturing or immediately after production, failing to test cells that have been used for a period or are nearing the end of their lifespan. Therefore, they cannot guarantee good sealing throughout the entire battery's lifespan.

[0004] During prolonged use, electrolyte loss occurs in battery cells. Accumulated loss can affect cell performance. To meet lifespan requirements, it's essential to ensure that accumulated loss doesn't impact performance throughout the lifespan. However, this process actually occurs over long periods and is difficult to verify in practice. Therefore, it's necessary to design an efficient, feasible, and reasonable solution to address the durability and sealing performance of the battery cell throughout its entire lifespan. Summary of the Invention

[0005] According to a first aspect of the present invention, a method for testing lithium-ion cells is provided, the method comprising the following steps: dividing lithium-ion cells into a first group and a second group; testing the performance of the first group in a first environment and testing the performance of the second group in a second environment; recording the tested performance of the first group and the second group at predetermined time intervals; and deriving the performance changes of the lithium-ion cells based on the tested performance of the first group and the second group.

[0006] Optionally, according to one or more embodiments of the first aspect, the test is a charge-discharge cycle test or a state of charge storage test performed on the first combination and the second combination.

[0007] Optionally, according to one or more embodiments of the first aspect, the test includes testing the quality, capacity, DC internal resistance, power, and helium leakage performance of the lithium-ion cell.

[0008] Optionally, according to one or more embodiments of the first aspect, the ambient temperature and ambient humidity in the first environment and the second environment are adjusted by the user.

[0009] Optionally, according to one or more embodiments of the first aspect, the first environment is a normal temperature and humidity environment and the second environment is a high temperature and low humidity environment.

[0010] Optionally, according to one or more embodiments of the first aspect, deriving the performance changes of the lithium-ion cell includes deriving the equivalent checkpoint K and / or failure time point N of the lithium-ion cell.

[0011] Optionally, according to one or more embodiments of the first aspect, the equivalent check point K of the lithium-ion cell is calculated by the following formula: K=(12n×m0×b) / (m1×a), where a is the time when the first combination performs normally under the first environment, b is the time when the second combination performs normally under the second environment, m0 is the mass loss of the first combination under the first environment for time a, m1 is the mass loss of the second combination under the second environment for time b, and n is the vehicle warranty period.

[0012] Optionally, according to one or more embodiments of the first aspect, the failure time point N of the lithium-ion battery cell is calculated by the following formula: N = m2 × a / m0, where a is the time during which the first combination performs normally under the first environment, m0 is the mass loss of the first combination during the time a under the first environment, and m2 is the mass loss of the second combination during the test under the second environment where it performs abnormally.

[0013] According to a second aspect of the present invention, a testing system for lithium-ion battery cells is provided, characterized in that the method comprises the following modules: a grouping module configured to divide lithium-ion battery cells into a first group and a second group; a testing module configured to test the performance of the first group under a first environment and test the performance of the second group under a second environment; a recording module configured to record the tested performance of the first group and the second group at predetermined time intervals; and a derivation module configured to deduce the performance changes of the lithium-ion battery cells based on the tested performance of the first group and the second group.

[0014] Optionally, according to one or more embodiments of the second aspect, the test is a charge-discharge cycle test or a state of charge storage test performed on the first combination and the second combination.

[0015] Optionally, according to one or more embodiments of the second aspect, the test includes testing the quality, capacity, DC internal resistance, power, and helium leakage performance of the lithium-ion cell.

[0016] Optionally, according to one or more embodiments of the second aspect, the ambient temperature and ambient humidity in the first environment and the second environment are adjusted by the user.

[0017] Optionally, according to one or more embodiments of the second aspect, the first environment is a normal temperature and humidity environment and the second environment is a high temperature and low humidity environment.

[0018] Optionally, according to one or more embodiments of the second aspect, deriving the performance changes of the lithium-ion cell includes deriving the equivalent checkpoint K and / or failure time point N of the lithium-ion cell.

[0019] Optionally, according to one or more embodiments of the second aspect, the equivalent check point K of the lithium-ion cell is calculated by the following formula: K=(12n×m0×b) / (m1×a), where a is the time when the first combination performs normally under the first environment, b is the time when the second combination performs normally under the second environment, m0 is the mass loss of the first combination under the first environment for time a, m1 is the mass loss of the second combination under the second environment for time b, and n is the vehicle warranty period.

[0020] Optionally, according to one or more embodiments of the second aspect, the failure time point N of the lithium-ion battery cell is calculated by the following formula: N=m2×a / m0, where a is the time during which the first combination performs normally under the first environment, m0 is the mass loss of the first combination during the time a under the first environment, and m2 is the mass loss of the second combination during the test under the second environment where it performs abnormally.

[0021] According to a third aspect of the present invention, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement a method for detecting lithium-ion cells as described in any embodiment of the first aspect of the present invention.

[0022] According to a fourth aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, wherein the program, when executed by a processor, implements the lithium-ion cell detection method as described in any embodiment of the first aspect of the present invention.

[0023] This invention provides a testing method and system for lithium-ion battery cells. It primarily addresses the cumulative effect of electrolyte loss during subsequent use, accelerating the simulation of the entire battery cell lifecycle to effectively verify the cell's sealing durability and ensure safe use. The testing method and system can simulate the actual usage conditions of the battery cell, evaluate the impact of slight sealing defects on electrolyte loss during use, calculate the equivalent sealing checkpoints within the warranty period, and obtain the equivalent number of years of failure, thereby simulating the battery cell's sealing durability life.

[0024] By incorporating the figures in this article and subsequently the appendix Figure 1 The specific embodiments used to illustrate certain principles of the invention will make other features and advantages of the methods and systems of the invention clearer or more apparent. Attached Figure Description

[0025] The above and / or other aspects and advantages of the present invention will become clearer and more readily understood from the following description taken in conjunction with the accompanying drawings, in which like or similar elements are denoted by the same reference numerals. The drawings include:

[0026] Figure 1 This is a flowchart of a lithium-ion battery cell testing method 100 according to an embodiment of the present invention.

[0027] Figure 2 This is a block diagram of a lithium-ion battery cell detection system 200 according to an embodiment of the present invention.

[0028] Figure 3 This is a schematic block diagram of a computer device according to an embodiment of the present invention. Detailed Implementation

[0029] In this specification, the invention is described more fully with reference to the accompanying drawings, which illustrate exemplary embodiments of the invention. However, the invention may be implemented in various forms and should not be construed as being limited to the embodiments given herein. The given embodiments are intended to make the disclosure herein complete and thorough, so as to more fully convey the scope of protection of the invention to those skilled in the art.

[0030] Terms such as "comprising" and "including" indicate that, in addition to the units and steps that are directly and explicitly stated in the specification, the technical solution of the present invention does not exclude the presence of other units and steps that are not directly or explicitly stated. Terms such as "first" and "second" do not indicate the order of the units in terms of time, space, size, etc., but are merely used to distinguish the units.

[0031] The invention is described below with reference to flowchart illustrations, block diagrams, and / or flowcharts of methods and systems according to embodiments of the invention. It will be understood that each block of these flowchart illustrations and / or block diagrams, and combinations thereof, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to constitute a machine, such that these instructions, executable by the processor of the computer or other programmable data processing apparatus, create components for implementing the functions / operations specified in these flowchart illustrations and / or blocks and / or one or more flowchart illustrations.

[0032] Figure 1 This is a flowchart of a lithium-ion battery cell testing method 100 according to an embodiment of the present invention. Figure 1 As shown, method 100 includes the following steps: step 101, dividing lithium-ion cells into a first group and a second group; step 102, testing the performance of the first group in a first environment and testing the performance of the second group in a second environment; step 103, recording the tested performance of the first group and the second group at predetermined time intervals; and step 104, deriving the performance changes of the lithium-ion cells based on the tested performance of the first group and the second group.

[0033] In step 101, several lithium-ion cells with good consistency (e.g., four) are selected and divided into a first group and a second group. The first group serves as the control group, while the second group serves as the experimental group. Users can select several (e.g., four) cells with good consistency. The consistency assessment includes determining whether the cells' capacity, power, DC internal resistance, and other performance parameters are similar. For example, the power error among several cells with good consistency should be within 5%. The consistency of performance parameters can be defined by the user; a smaller performance parameter error range indicates better cell consistency.

[0034] Subsequently, a vacuum helium test can be performed on the battery cell to detect its helium leakage rate, thereby ensuring that the helium leakage rate is within the acceptable range. For example, the helium leakage rate of the battery cell should be within (0.26~0.36)×10⁻⁶. -7 Pa×m 3 Within the range of / s, where Pa×m 3 / s is the leakage rate unit, representing the amount of gas leaked within a cubic space per unit time. The battery cells were then divided into two groups (control group and experimental group) and placed in different environments for charge-discharge cycle testing or state-of-charge (SOC) storage testing. These environments can correspond to different ambient temperatures and humidity levels. Note that the ambient temperature unit referred to in this article is degrees Celsius (°C), but other units of temperature measurement can also be used. Ambient humidity is relative humidity, which is the ratio of the vapor pressure of water in the air to the saturated vapor pressure of water at the same temperature and pressure. Humidity is 100% when the air is saturated with moisture. Other units of humidity measurement can also be used to measure temperature.

[0035] In step 102, the control group (first group) is placed in a first environment with normal temperature and humidity. Normal temperature can be the average annual temperature of the area where the battery cell is used, and can be controlled, for example, between 20°C and 35°C. Normal humidity can be the average annual humidity of the area where the battery cell is used, and can be controlled, for example, between 30% and 60%. Simultaneously, the experimental group (second group) is placed in a second environment in a temperature-adjustable and insulated sealed container, and the environment inside the container can be dehumidified to ensure that the environment is at a certain humidity level. For example, the control group can be placed in the first environment with normal temperature and humidity (e.g., 25°C, 45% humidity), and the experimental group can be placed in a second environment of any combination of high temperature and low humidity (e.g., 35°C, 30% humidity), low temperature and high humidity (e.g., 20°C, 60% humidity), high temperature and high humidity (e.g., 35°C, 60% humidity), or low temperature and low humidity (e.g., 20°C, 30% humidity). Note that the above environmental temperatures and humidity levels are only examples; the specific high temperature, low temperature, high humidity, and low humidity can be defined by the user relative to normal temperature and humidity.

[0036] Optionally, in one embodiment, the first environment in which the control group (first combination) is located can also be constructed by a sealed container with adjustable temperature, insulation, and humidity. The sealed container can maintain the temperature and humidity of the first environment at normal temperature and humidity as described above.

[0037] In step 103, charge-discharge cycle tests or state of charge (SOC) storage tests are initiated for the control group and the experimental group, and performance parameters such as the mass, capacity, DC internal resistance, power, and helium leakage rate of the two groups of cells are recorded at regular intervals (the recording intervals for the control group and the experimental group can be the same or different).

[0038] In step 104, cell parameters are recorded, and the performance changes of the lithium-ion cell are derived based on these parameters. For example, three sets of parameters are recorded to deduce the equivalent checkpoint K for the warranty period and / or the equivalent number of years of failure N for the cell. The three sets of parameters are: for the control group, no abnormalities are found in the basic performance check after 1 month (i.e., no significant changes in performance parameters) and the mass loss is m0; for the experimental group, no abnormalities are found in the basic performance check after 1 month (i.e., significant changes in performance parameters, such as a helium leakage rate greater than 15%, which can be defined by the user) and the mass loss is m2. If the vehicle warranty period is n years, the normal electrolyte loss is m0 / a per month, the total electrolyte loss during the warranty period is 12n×m0 / a, and the monthly electrolyte consumption of the experimental group is m1 / b. Thus, the equivalent checkpoint for the warranty period can be derived.

[0039] K = (12n × m0 × b) / (m1 × a);

[0040] as well as

[0041] Failure equivalent years:

[0042] N = m² × a / m₀. Note that in this invention, for simplicity, following automotive manufacturing conventions, the testing time a / b is in months, and the warranty period n / failure time N is in years. The formula 360 days = 12 months = 1 year can be used to convert the dates accordingly. Other date calculation units can also be used in the technical solution of this invention; similarly, other quality calculation units can also be used in the technical solution of this invention.

[0043] In a preferred embodiment, to facilitate the evaporation of the electrolyte within the cell, the sealed container of the experimental group can be dehumidified, with the ambient humidity controlled below 20%. Optionally, to facilitate the evaporation of the electrolyte within the cell, the sealed container of the experimental group can also be heated, with the temperature controlled above 60°C. Cyclic experiments are conducted on the cells, with the same procedures for both groups. The experiments can be carried out within the usable temperature range of the cells, selecting an available charge / discharge rate (1C) for charging and discharging. Here, C is a unit of ratio for the battery charge / discharge current obtained from the capacity check; for example, if a cell is discharged completely in 1 hour, the discharge current is called 1C. The performance parameters of the experimental group are tested at regular intervals (e.g., 15 days), while the performance parameters of the control group are checked at regular intervals (e.g., 30 days). Based on the methods described above, the equivalent check point K for the warranty period and / or the equivalent number of years of failure N for the cells are derived.

[0044] In a preferred embodiment, storage experiments can also be performed on the battery cells. For example, the state of charge (SOC) of the battery cells is selected to be between 50% and 90%. The performance parameters of the experimental group are tested at regular intervals (e.g., 15 to 30 days), while the performance parameters of the control group are checked at regular intervals (e.g., 1 to 3 months). Based on the methods described above, the equivalent check point K for the warranty period and / or the equivalent number of years of failure N for the battery cells are derived.

[0045] In the above embodiments, the pulse current ratio used for DC internal resistance checking can be between 1C and 0.8Imax, where Imax is the maximum usable current limit of the battery cell. The helium detection vacuum level can be controlled below -80MPa, thereby ensuring that even minute leaks are detected. In the above embodiments, a weight sensor such as a balance can be used to detect changes in the battery cell's mass, with an accuracy of more than one ten-thousandth.

[0046] Figure 2 This is a block diagram of a lithium-ion battery cell detection system 200 according to an embodiment of the present invention. Figure 2 As shown, system 200 includes the following modules: a grouping module 201 configured to divide lithium-ion cells into a first group and a second group; a testing module 202 configured to test the performance of the first group in a first environment and the performance of the second group in a second environment; a recording module 203 configured to record the tested performance of the first group and the second group at predetermined time intervals; and a derivation module 204 configured to deduce the performance changes of the lithium-ion cells based on the tested performance of the first group and the second group.

[0047] The grouping module 201 can select multiple (e.g., four) lithium-ion cells with good consistency and divide them into a first group and a second group. The first group serves as the control group, while the second group serves as the experimental group. Users can select multiple (e.g., four) cells with good consistency, where consistency is judged by whether the cell's capacity, power, DC internal resistance, and other performance parameters are similar. For example, the power error among multiple cells with good consistency should be within 5%. The judgment of performance parameter consistency can be defined by the user; a smaller performance parameter error range indicates better cell consistency.

[0048] Subsequently, a vacuum helium test can be performed on the battery cell to detect its helium leakage rate, thereby ensuring that the helium leakage rate is within the acceptable range. For example, the helium leakage rate of the battery cell should be within (0.26~0.36)×10⁻⁶. -7 Pa×m 3Within a range of / s. Then, the grouping module 201 divides the battery cells into two groups (control group and experimental group) and places them in different environments for charge-discharge cycle testing or state-of-charge (SOC) storage testing. The environment can correspond to different ambient temperatures and humidity levels. Note that the ambient temperature unit referred to in this article is degrees Celsius (°C), but other temperature measurement units can also be used. Ambient humidity is relative humidity, which is the ratio of the vapor pressure of water in the air to the saturated vapor pressure of water at the same temperature and pressure. When the moisture content in the air reaches saturation, the humidity is 100%. Other humidity measurement units can also be used to measure temperature.

[0049] The testing module 202 can place the control group (first group) in a first environment with normal temperature and humidity. Normal temperature can be the annual average temperature of the area where the battery cells are used, and can be controlled, for example, between 20°C and 35°C. Normal humidity can be the annual average humidity of the area where the battery cells are used, and can be controlled, for example, between 30% and 60%. Simultaneously, the testing module 202 places the experimental group (second group) in a second environment within a temperature-adjustable and insulated sealed container, and can dehumidify the environment inside the container to ensure it is at a certain humidity level. For example, the control group can be placed in the first environment with normal temperature and humidity (e.g., 25°C, 45% humidity), and the experimental group can be placed in a second environment with any combination of high temperature and low humidity (e.g., 35°C, 30% humidity), low temperature and high humidity (e.g., 20°C, 60% humidity), high temperature and high humidity (e.g., 35°C, 60% humidity), or low temperature and low humidity (e.g., 20°C, 30% humidity). Note that the above environmental temperatures and humidity levels are only examples; the specific high temperature, low temperature, high humidity, and low humidity can be defined by the user relative to normal temperature and humidity.

[0050] Optionally, in one embodiment, the first environment in which the control group (first combination) is located can also be constructed by a sealed container with adjustable temperature, insulation, and humidity. The sealed container can maintain the temperature and humidity of the first environment at normal temperature and humidity as described above.

[0051] The recording module 203 can enable charge-discharge cycle testing or state-of-charge storage testing for the control group and experimental group, and record the performance parameters of the two groups of cells, such as mass, capacity, DC internal resistance, power, and helium leakage rate, at regular intervals (the recording intervals for the control group and experimental group can be the same or different).

[0052] The derivation module 204 can record cell parameters and deduce the performance changes of the lithium-ion cell based on these parameters. For example, the derivation module 204 can record three sets of parameters to deduce the equivalent check point K of the warranty period and / or the equivalent number of years of failure N of the cell. The three sets of parameters are: the control group has no abnormalities in the basic performance check after a month of experiment (i.e., no significant change in performance parameters) and a mass loss of m0; the experimental group has no abnormalities in the basic performance check after b months of experiment and a mass loss of m1; and the experimental group has an abnormality found in the basic performance check (i.e., a significant change in performance parameters, such as a helium leakage rate greater than 15%, which can be defined by the user) and a mass loss of m2. If the vehicle warranty period is n years, the normal electrolyte loss is m0 / a per month, the total electrolyte loss during the warranty period is 12n×m0 / a, and the monthly electrolyte consumption of the experimental group is m1 / b.

[0053] Therefore, the equivalent checkpoints for the warranty period can be derived:

[0054] K = (12n × m0 × b) / (m1 × a);

[0055] as well as

[0056] Failure equivalent years:

[0057] N = m2 × a / m0.

[0058] In a preferred embodiment, to facilitate the evaporation of the electrolyte within the cell, the sealed container of the experimental group can be dehumidified, with the ambient humidity controlled below 20%. Optionally, to facilitate the evaporation of the electrolyte within the cell, the sealed container of the experimental group can also be heated, with the temperature controlled above 60°C. Cyclic experiments are conducted on the cells, with the same procedures for both groups. The experiments can be carried out within the usable temperature range of the cells, selecting an available charge / discharge rate (1C) for charging and discharging. Here, C is a unit of ratio for the battery charge / discharge current obtained from the capacity check; for example, if a cell is discharged completely in 1 hour, the discharge current is called 1C. The performance parameters of the experimental group are tested at regular intervals (e.g., 15 days), while the performance parameters of the control group are checked at regular intervals (e.g., 30 days). Based on the methods described above, the equivalent check point K for the warranty period and / or the equivalent number of years of failure N for the cells are derived.

[0059] In a preferred embodiment, storage experiments can also be performed on the battery cells. For example, the state of charge (SOC) of the battery cells is selected to be between 50% and 90%. The performance parameters of the experimental group are tested at regular intervals (e.g., 15 to 30 days), while the performance parameters of the control group are checked at regular intervals (e.g., 1 to 3 months). Based on the methods described above, the equivalent check point K for the warranty period and / or the equivalent number of years of failure N for the battery cells are derived.

[0060] In the above embodiments, the pulse current ratio used for DC internal resistance checking can be between 1C and 0.8Imax, where Imax is the maximum usable current limit of the battery cell. The helium detection vacuum level can be controlled below -80MPa, thereby ensuring that even minute leaks are detected. In the above embodiments, a balance can be used to detect changes in the battery cell's mass, with an accuracy of more than one ten-thousandth.

[0061] The above description provides a method and system for testing the sealing durability of lithium-ion battery cells. Examples of applications of the described method and system will be described in detail below.

[0062] In one embodiment, charge-discharge cycle testing is performed on the battery cells. Four cells with good consistency (e.g., aluminum-cased cells) can be selected for vacuum helium testing, with a leak rate of (0.26~0.36)×10⁻⁶. -7 Pa×m 3 / s, confirming normal cell leakage rate. With all cells functioning normally, divide them into two groups: a control group and an experimental group. The control group can be placed in a normal temperature and humidity environment (25℃, 45%) for charge-discharge cycle testing. This cycle testing can include fast charging (e.g., 3C charging) and slow discharging (e.g., 1C discharging). The depth of discharge (DOD) is maintained at 100%, meaning the battery is completely discharged. The experimental group can be placed in a temperature-controlled, sealed container. The container environment is dehumidified to ensure humidity is maintained at 15%, while the ambient temperature is maintained at 45℃ through heating. Start the cell lifespan charge-discharge cycle test for both the control and experimental groups. For the experimental group, check the cell quality, capacity, DC internal resistance, power, helium leakage rate, and other performance parameters every 15 days. For the control group, check the cell quality, capacity, DC internal resistance, power, helium leakage rate, and other performance parameters every 90 days. The cell warranty can be set to 10 years.

[0063] In this scenario, the tested performance parameters change as follows: For the experimental group, the cell mass loss after 180 days of testing was 0.0042g; when the mass loss reached 0.0132g, the experimental group exhibited a large capacity decay rate and abnormally increased DC internal resistance, indicating that the cell had begun to fail. For the control group, the mass loss after 360 days of testing was 0.0012g. Therefore, according to the formula for calculating the equivalent checkpoint K, the warranty period equivalent checkpoint K = 17.14 months = 514.28 days can be calculated. According to the formula for calculating the equivalent number of years of failure N, N = 11 years > 10 years. At this point, the control group test can be stopped, and only the experimental group test can be performed up to 514 days. At 514 days, the mass loss was 0.0118g, which can be considered as reaching the warranty equivalent point. Simultaneously, the cell's helium leakage rate and other basic performance checks are checked to ensure they meet requirements. For example, at 514 days, the helium detection value of the experimental group was 0.94 × 10⁻⁶. -7 Pa×m3 / s, which meets the required helium leakage rate. Therefore, it can be deduced that the sealing durability of this battery cell will be normal during the warranty period, and can be maintained for at least beyond the warranty period while maintaining sealing durability.

[0064] In another embodiment, the above charge-discharge cycle test can be changed to a cell state-of-charge (SOC) storage test. Specifically, four cells with good consistency (e.g., pouch cells) are selected and subjected to vacuum helium testing. The leakage rate of the vacuum helium test is (0.42~0.54)×10⁻⁶. -7 Pa×m 3 / s, confirming normal cell leakage rate. Then, the cells are divided into two groups: a control group and an experimental group. The control group is stored in a normal temperature and humidity environment (25℃, 40%) for storage testing, with the maximum state of charge (SOC) set at 80%. The experimental group is placed in a temperature-controlled, sealed container. The container environment is dehumidified to maintain humidity at 20%. The container is also heated to maintain the ambient temperature at 60℃. Lifetime cyclic storage testing is then initiated for both the control and experimental groups. Every 30 days, the basic performance of the experimental group's cells, including cell quality, capacity, DC internal resistance, power, and helium leakage rate, is checked. Every 90 days, the basic performance of the cells, including cell quality, capacity, DC internal resistance, power, and helium leakage rate, is checked. The cell warranty can be set to 10 years.

[0065] In this scenario, the tested performance parameters change as follows: For the experimental group, the cell mass loss after 180 days of testing was 0.0154g with no performance abnormalities. When the experimental group's mass loss reached 0.0263g, a large capacity decay rate and abnormally increased DC internal resistance appeared, indicating the onset of failure. For the control group, the mass loss after 360 days of testing was 0.0027g. Therefore, according to the formula for calculating the equivalent checkpoint K, the equivalent checkpoint for the warranty period can be calculated as K = 10.5 months = 315 days. According to the formula for calculating the equivalent number of years of failure N, N = 116 months = 9.74 years < 10 years. At this point, the control group test can be stopped, and only the experimental group test can be performed until the experimental group's mass loss reaches 0.0263g. Simultaneously, check whether other basic performance checks, such as the cell's helium leakage rate, meet the requirements. For example, at 315 days, the helium detection value of the experimental group is 0.12 × 10⁻⁶. -7 Pa×m 3 The cell's helium leakage rate meets the required standard. However, because the cell's failure time is 9.74 years, it does not meet the quality requirements.

[0066] In another embodiment, the above charge-discharge cycle test can be modified to a state-of-charge (SOC) storage test for aluminum-cased cells with different storage capacities. Specifically, four aluminum-cased cells with good consistency are selected and subjected to vacuum helium testing. The leakage rate of the vacuum helium testing is (0.38~0.43)×10⁻⁶. -7 Pa×m3 / s, confirming normal cell leakage rate. Then, the cells are divided into two groups: a control group and an experimental group. The control group is stored in a normal temperature and humidity environment (25℃, 40%) for storage testing, with the maximum state of charge (SOC) set at 50%. The experimental group is placed in a temperature-controlled, sealed container. The container environment is dehumidified to maintain humidity at 20%. The container is also heated to maintain the ambient temperature at 55℃. Life cycle storage tests are then initiated for both the control and experimental groups. Every 30 days, the basic performance of the experimental group's cells, including cell quality, capacity, DC internal resistance, power, and helium leakage rate, is checked. Every 90 days, the basic performance of the cells, including cell quality, capacity, DC internal resistance, power, and helium leakage rate, is checked. The cell warranty can be set to 12 years.

[0067] In this scenario, the tested performance parameters change as follows: For the experimental group, the cell mass loss after 180 days of testing was 0.0132g. When the mass loss of the experimental group reached 0.0354g, a large capacity decay rate and abnormally increased DC internal resistance were observed, indicating the onset of failure. For the control group, the mass loss after 360 days of testing was 0.0021g. Therefore, according to the formula for calculating the equivalent checkpoint K, the equivalent checkpoint K for the warranty period can be calculated as K = 9.54 months = 286.3 days. According to the formula for calculating the equivalent number of years of failure N, N = 16.85 years > 12 years. At this point, the control group test can be stopped, and only the experimental group test should be performed until the mass loss reaches 0.0354g. Simultaneously, the cell's helium leakage rate and other basic performance checks should be performed to ensure they meet requirements. For example, at 286 days, the helium detection value of the experimental group was 0.17 × 10⁻⁶. -7 Pa×m 3 / s, which meets the required helium leakage rate. Therefore, it can be concluded that the cell has no abnormalities in sealing durability during the warranty period and can maintain sealing durability for at least 12 years.

[0068] Figure 3 This is a schematic block diagram of a computer device according to an embodiment of the present invention. Figure 3 As shown, according to another aspect of the present invention, a computer-readable storage medium is also provided, on which a computer program is stored, which, when executed by a processor, can implement the above-described lithium-ion cell detection method.

[0069] The embodiments and examples presented herein are provided to best illustrate embodiments according to the present technology and its particular applications, thereby enabling those skilled in the art to practice and use the invention. However, those skilled in the art will understand that the above description and examples are provided merely for ease of illustration and example. The descriptions presented are not intended to cover all aspects of the invention or to limit the invention to the precise forms disclosed.

Claims

1. A method for detecting lithium-ion battery cells, characterized in that, The method includes the following steps: The lithium-ion battery cells are divided into a first group and a second group; The performance of the first combination was tested in a first environment, and the performance of the second combination was tested in a second environment. Record the performance of the first combination and the second combination at predetermined time intervals; as well as The performance changes of the lithium-ion battery cell are deduced based on the performance tests conducted using the first combination and the second combination. The first environment is a normal temperature and humidity environment, and the second environment is an environment with a temperature above 60°C and humidity below 20%. The deduction of the performance changes of the lithium-ion battery cell includes deriving the failure time point N of the lithium-ion battery cell. The failure time point N of the lithium-ion battery cell is calculated using the following formula: N = m² × a / m₀, where, a represents the time during which the first combination performs normally under the first environment, m0 represents the quality loss of the first combination during the time a under the first environment, and m2 represents the quality loss of the second combination during the time a under the second environment.

2. The method according to claim 1, wherein, The test is a charge-discharge cycle test or a state of charge storage test performed on the first combination and the second combination.

3. The method according to claim 1 or 2, wherein, The tests include testing the quality, capacity, DC internal resistance, power, and helium leakage performance of the lithium-ion cell.

4. The method according to claim 3, wherein, The ambient temperature and humidity in the first and second environments are adjusted by the user.

5. The method according to claim 1, wherein, The derivation of the performance variation of the lithium-ion battery cell also includes deriving the equivalent checkpoint K of the lithium-ion battery cell, which is calculated using the following formula: K = (12n × m0 × b) / (m1 × a), where, a represents the time during which the first combination performs normally under the first environment, b represents the time during which the second combination performs normally under the second environment, m0 represents the quality loss of the first combination during test time a under the first environment, m1 represents the quality loss of the second combination during test time b under the second environment, and n represents the vehicle warranty period, with a and b in months and n in years.

6. A detection system for lithium-ion battery cells, characterized in that, The system includes the following modules: A grouping module, configured to divide lithium-ion cells into a first group and a second group; A testing module is configured to test the performance of the first combination in a first environment and the performance of the second combination in a second environment. A recording module configured to record the performance of the first combination and the second combination tested at predetermined time intervals; as well as The derivation module is configured to deduce the performance changes of the lithium-ion battery cell based on the performance tested by the first combination and the second combination. The first environment is a normal temperature and humidity environment, and the second environment is an environment with a temperature above 60°C and a humidity below 20%. Deducing the performance changes of the lithium-ion battery cell includes deduce the failure time point N of the lithium-ion battery cell, which is calculated using the following formula: N = m² × a / m₀, where, a represents the time during which the first combination performs normally under the first environment, m0 represents the quality loss of the first combination during the time a under the first environment, and m2 represents the quality loss of the second combination during the time a under the second environment.

7. The system according to claim 6, wherein, The test is a charge-discharge cycle test or a state of charge storage test performed on the first combination and the second combination.

8. The system according to claim 6 or 7, wherein, The tests include testing the quality, capacity, DC internal resistance, power, and helium leakage performance of the lithium-ion cell.

9. The system according to claim 8, wherein, The ambient temperature and humidity in the first and second environments are adjusted by the user.

10. The system according to claim 6, wherein, The derivation of the performance variation of the lithium-ion battery cell also includes deriving the equivalent checkpoint K of the lithium-ion battery cell, which is calculated using the following formula: K = (12n × m0 × b) / (m1 × a), where, a represents the time during which the first combination performs normally under the first environment, b represents the time during which the second combination performs normally under the second environment, m0 represents the quality loss of the first combination during test time a under the first environment, m1 represents the quality loss of the second combination during test time b under the second environment, and n represents the vehicle warranty period, with a and b in months and n in years.

11. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The processor executes the computer program to achieve: The method for testing lithium-ion cells as described in any one of claims 1-5.

12. A computer-readable storage medium storing a computer program thereon, characterized in that, The computer program can be implemented when executed by a processor: The method for testing lithium-ion cells as described in any one of claims 1-5.

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