A lithium-ion battery high temperature cycle aging test control system and method

Abstract

The invention discloses a lithium-ion battery high-temperature cycle aging test control system and method, and relates to the technical field of lithium battery testing; the lithium-ion battery high-temperature cycle aging test control system comprises a preliminary detection module, an aging test module, a risk management module and an aging assessment module: the preliminary detection module, the technical key points of which are: pre-detecting the lithium battery before the high-temperature cycle aging test, screening out abnormal lithium batteries, and then constructing a lithium battery group with the qualified lithium batteries after screening, and using the lithium battery group for testing, the test result is more in line with the actual situation, the obtained data is more standard, and the use of this step can reduce the impact of battery differences in the lithium battery group, can effectively reduce the risk of high-temperature cycle aging test, so that the safety of high-temperature cycle aging test is improved, and has a good prospect of use.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery testing, and in particular to a lithium ion battery high temperature cycle aging test control system and method. Background Art

[0002] Lithium-ion battery is a secondary battery (rechargeable battery) that mainly relies on the movement of lithium ions between the positive electrode and the negative electrode to work. During the charge and discharge process, Li+ is intercalated and deintercalated between the two electrodes: when charging, Li+ is deintercalated from the positive electrode and intercalated into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; the opposite is true during discharge.

[0003] After lithium-ion batteries are produced, battery life tests will be conducted on them to help relevant technicians understand the quality of this batch of lithium-ion batteries.

[0004] Battery life tests are divided into three types: calendar life test, cycle decay test and accelerated aging test. Among them, calendar life test refers to the battery being in a static state; cycle decay test mainly studies the process of battery reaching the end of life or failure during continuous charge and discharge; accelerated aging test is to set additional conditions on the basis of cycle test, such as excessive charge and discharge, placement in high and low temperature environment, etc., so that the performance of the object under test is degraded faster, accelerating the process of reaching the end of life or failure.

[0005] The invention patent with the existing application publication number CN114397591A and the name of a lithium battery life acceleration test method records that it includes: taking multiple batteries, performing initial capacity measurement on each of the batteries, and randomly dividing the multiple batteries after the initial capacity measurement into a normal temperature and pressure group and a high temperature vacuum group, wherein the batteries in the normal temperature and pressure group are first batteries, and the batteries in the high temperature vacuum group are second batteries; and performing charge and discharge cycles on the multiple first batteries at normal temperature and pressure in preset steps. The lithium battery life acceleration test method accelerates the life of the lithium battery through two acceleration conditions of temperature and vacuum, accelerates the battery life decay, shortens the test time, and reduces the test cost.

[0006] The above patent gives the difference multiple relationship between the cycle decay test under normal environment and high temperature conditions. Therefore, when conducting a battery life test on the battery, the cycle decay test and the accelerated aging test can be used in conjunction with each other to conduct a high-temperature cycle aging test. However, during the high-temperature cycle aging test, the working environment of the lithium battery changes due to the influence of high temperature, which can easily cause lithium battery explosions, etc. There are certain risks, which may cause damage to the test equipment and cause certain losses. At the same time, if the test equipment is damaged, the test data will be lost, resulting in unnecessary repeated experiments. In order to reduce the risk during testing and improve efficiency at the same time, the existing solution only uses batteries for detection, and the battery pack will affect each other when working, such as affecting the heat dissipation effect, and there is a pressure difference between lithium batteries. Therefore, the existing test cannot reflect the actual use effect of the battery pack, and the data obtained is not standard. For this reason, we have developed a lithium-ion battery high-temperature cycle aging test control system and method. Summary of the invention

[0007] 1. Technical issues to be resolved

[0008] In view of the deficiencies in the prior art, the present invention provides a lithium-ion battery high-temperature cycle aging test control system and method, which solves the problems raised in the background technology.

[0009] (II) Technical solution

[0010] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0011] A lithium-ion battery high-temperature cycle aging test control system, including a preliminary detection module, an aging test module, a risk control module and an aging assessment module:

[0012] The preliminary detection module obtains the high-temperature cycle loss test data of Z lithium batteries produced in the same batch, calculates the capacity loss rate of all lithium batteries, and compares the capacity loss rate of the lithium batteries with the preset standard threshold range, removes the lithium batteries that do not meet the standard threshold range, and randomly selects A lithium batteries from the lithium batteries that meet the standard threshold to build a lithium battery pack;

[0013] The aging test module performs N times of charge and discharge tests at a set temperature according to the set charge and discharge strategy, and collects the working data of the lithium battery pack in the high-temperature cycle aging test and the data of the lithium battery pack after the high-temperature cycle aging test in real time;

[0014] The risk control module obtains the working data of the lithium battery pack under the high-temperature cycle aging test in real time, and builds a risk assessment model to predict the risk assessment value Fxpg of the battery during the high-temperature cycle aging test, and compares the risk assessment value with the preset safety warning threshold, and chooses whether to interrupt the aging test module based on the comparison result;

[0015] The aging assessment module obtains the lithium battery parameter data and risk assessment value Fxpg of the lithium battery pack after the high-temperature cycle aging test in real time, and builds an aging assessment model to calculate the loss degree assessment value Shpg of the lithium battery pack, and compares the loss degree assessment value with the preset battery loss threshold. According to the comparison result, it is decided whether to start the aging test module for retesting.

[0016] Furthermore, the high temperature cycle loss test data of the lithium battery is the initial power of the lithium battery and the power data after 5 consecutive charge and discharge cycles at 60°C. The discharge process is to discharge from the upper limit voltage at a constant current of 1C to the termination voltage, and the charging process is to charge from the termination voltage at a constant current of 1C to the upper limit voltage, and then charge at a constant voltage until the charging current is reduced to 0.05C.

[0017] The calculation formula of capacity loss rate is as follows:

[0018]

[0019] In the formula, is the capacity loss rate of lithium battery, It is the capacity of lithium battery after high temperature cycle aging test. is the initial capacity of the lithium battery.

[0020] Furthermore, the preset standard threshold interval is ,in is the average value of the capacity loss rate of several lithium batteries produced in the same batch. .

[0021] Furthermore, the steps of the aging test module for charge and discharge testing are as follows:

[0022] S1. Discharge test: Discharge from the upper limit voltage to the end voltage at 1C constant current at 55℃ and leave for 20 minutes;

[0023] S2, charging test: at 55℃, charge at 1C constant current to the upper limit voltage, then charge at constant voltage until the charging current decreases to 0.05C, leave for 20 minutes, count once, count the result and compare it with N. When the result is less than N, repeat S1. When the result is equal to N, suspend the aging test.

[0024] The total number of measurements of lithium battery pack is When N is 30, the total number of measurements of the lithium battery pack is , N is 20, the total number of measurements of the lithium battery pack is When the total number of measurements of the lithium battery pack is greater than 500, N is 10.

[0025] Furthermore, the working data in the high temperature cycle aging test of the lithium battery pack includes the battery deformation, battery surface temperature, hydrogen content and carbon dioxide content, and the data after the high temperature cycle aging test of the lithium battery pack includes the capacity of all lithium batteries in the lithium battery pack.

[0026] Furthermore, the process of the risk assessment model is as follows:

[0027] Real-time extraction of the working data of the lithium battery pack during the high-temperature cycle aging test, and recording the time point corresponding to the working data;

[0028] The risk assessment value Fxpg of the lithium battery pack during the high temperature cycle aging test is predicted based on the extracted data and the corresponding time. The specific calculation formula is as follows:

[0029]

[0030] In the formula, is the risk assessment value of the lithium battery pack during the nth test, is the calculated risk assessment value caused by temperature, is the battery deformation at the nth detection, is the influence coefficient of the risk assessment value corresponding to the battery deformation, is the hydrogen content at the nth detection, is the hydrogen content in the air, is the influence coefficient of the risk assessment value corresponding to hydrogen, is the carbon dioxide content at the nth detection, is the carbon dioxide content in the air, is the impact coefficient of the risk assessment value corresponding to carbon dioxide;

[0031] is the surface temperature of the lithium battery pack during the nth detection, is the surface temperature of the lithium battery pack during the n-1th detection, is the influence coefficient of instantaneous temperature change on risk assessment value, is the influence coefficient of temperature on risk assessment value, It is the interval time between the n-1th detection time point and the nth detection time point.

[0032] Further, the preset safety warning threshold includes a warning threshold Jsyz and an interruption threshold Zdyz, and Zdyz>Jsyz;

[0033] After comparing the risk assessment value with the preset safety warning threshold:

[0034] If the risk assessment value < warning threshold Jsyz, it means that the risk level of lithium battery is low, the aging test is carried out normally, and the risk control module does not respond;

[0035] If the warning threshold Jsyz ≤ risk assessment value < interruption threshold Zdyz, it means that the risk level of lithium batteries is high, and the risk control module issues a first-level warning and implements the detection cycle adjustment strategy;

[0036] If the interruption threshold Zdyz ≤ risk assessment value , it means that the risk level of lithium battery is high, the risk control module issues a secondary warning and interrupts the aging test;

[0037] The detection cycle adjustment strategy is implemented to shorten the interval time for collecting working data, and the formula based on it is as follows;

[0038]

[0039] In the formula, is the interval between the n-1th detection time point and the nth detection time point, is the risk assessment value at the n-1th detection, Risk Assessment Value <The interval between adjacent detection time points when the warning threshold Jsyz is is the floor function.

[0040] Furthermore, the calculation formula for calculating the loss evaluation value Shpg of the lithium battery pack is as follows:

[0041]

[0042] In the formula, , , , These are the data detected and calculated during the previous aging test corresponding to the loss evaluation value Shpg of the lithium battery pack. The number of times the working data under the high temperature cycle aging test was collected during the previous aging test corresponding to the loss degree evaluation value Shpg of the lithium battery pack, is the risk assessment value of the lithium battery pack during the i-th detection, is the risk assessment value of the lithium battery pack during the i-1th test, is the capacity of the i-th lithium battery after high temperature cycle aging test, is the initial capacity of the lithium battery, , is the preset proportional coefficient;

[0043] After comparing the loss degree assessment value Shpg of the lithium battery pack with the preset battery loss threshold Shyz;

[0044] If Shpg<Shyz, start the aging test module;

[0045] If Shpg≥Shyz, turn off the aging test module and the test ends.

[0046] Furthermore, it also includes a comprehensive evaluation module, which obtains the total number of tests Cssj of the aging test module, and calculates the high temperature cycle test data of the lithium ion group, the high temperature cycle test data is Cssj-N, and rates the batch of lithium battery packs according to the high temperature cycle test data of the lithium ion group, and gives a comprehensive score to the lithium battery packs produced in the batch;

[0047] When the high temperature cycle test data of the lithium battery pack is less than 250 times, the lithium battery pack is rated as level three;

[0048] When the high temperature cycle test data of the lithium battery pack is 250-500 times, the lithium battery pack is rated as Level 2;

[0049] When the high temperature cycle test data of the lithium battery pack is more than 500 times, the lithium battery pack is rated as level one;

[0050] The calculation formula for the comprehensive score of lithium batteries produced in this batch is as follows:

[0051]

[0052] In the formula, Provide a comprehensive score for the lithium batteries produced in this batch. The score corresponding to the lithium battery pack rating, For the number of lithium batteries eliminated, the corresponding score for a lithium battery pack rated level 3 is 60 points, the corresponding score for a lithium battery pack rated level 2 is 80 points, and the corresponding score for a lithium battery pack rated level 1 is 100 points.

[0053] Furthermore, a lithium-ion battery high temperature cycle aging test control method comprises the following steps:

[0054] Step 1: Obtain high temperature cycle loss test data of Z lithium batteries produced in the same batch, calculate the capacity loss rate of all lithium batteries, and compare the capacity loss rate of the lithium batteries with a preset standard threshold range, remove the lithium batteries that do not meet the standard threshold range, and randomly select A lithium batteries from the lithium batteries that meet the standard threshold to construct a lithium battery pack;

[0055] Step 2: Control the aging test equipment to perform N times of charge and discharge tests at a set temperature according to a set charge and discharge strategy, and collect the working data of the lithium battery pack in the high-temperature cycle aging test and the data of the lithium battery pack after the high-temperature cycle aging test in real time;

[0056] Step 3: Obtain the working data of the lithium battery pack under the high temperature cycle aging test in real time, and build a risk assessment model to predict the risk assessment value Fxpg of the battery during the high temperature cycle aging test, and compare the risk assessment value with the preset safety warning threshold, and choose whether to interrupt the aging test according to the comparison result;

[0057] Step 4: Obtain the lithium battery parameter data and risk assessment value Fxpg of the lithium battery pack after the high-temperature cycle aging test in real time, and build an aging assessment model to calculate the loss degree assessment value Shpg of the lithium battery pack, and compare the loss degree assessment value with the preset battery loss threshold, and choose whether to start the aging test for retesting according to the comparison result;

[0058] Step 5: Obtain the total number of tests Cssj, and calculate the high temperature cycle test data Cssj-N of the lithium ion battery pack, rate the batch of lithium battery packs according to the high temperature cycle test data, and give a comprehensive score to the lithium battery packs produced in the batch.

[0059] (III) Beneficial effects

[0060] The present invention provides a lithium-ion battery high temperature cycle aging test control system and method, which has the following beneficial effects:

[0061] Before the high-temperature cycle aging test, the lithium batteries are pre-tested to screen out abnormal lithium batteries, and then the qualified lithium batteries after screening are used to build a lithium battery pack. The lithium battery pack is used for testing. The test results are more in line with the actual situation and the data obtained are more standardized. In addition, this step can reduce the impact of battery differences in the lithium battery pack, effectively reduce the risk of the high-temperature cycle aging test, and improve the safety of the high-temperature cycle aging test.

[0062] During the high-temperature cycle aging test of the lithium-ion group, the working data of the lithium battery group is collected in real time, and the working data of the lithium battery group is further analyzed to obtain the risk assessment value of the lithium battery group, and the obtained risk assessment value of the lithium battery group is compared with the set safety warning threshold in real time, and the suddenness of the abnormality is comprehensively considered. When the risk assessment value is higher, the detection frequency is increased, which can ensure that the abnormality of the lithium battery pack is monitored at the first time, and the high-temperature cycle aging test is interrupted in time, so as to ensure the safety of related equipment and effectively reduce risks. At the same time, it can ensure the integrity of the test data, with good use effect and good use prospects.

[0063] The entire process of the high-temperature cycle aging test is divided into multiple stages. As the number of tests increases, the number of loss assessments of the lithium battery pack is gradually increased. Compared with the existing method of using a fixed test of 50 times per test, a more accurate number of lithium battery uses can be obtained, and the data obtained is more accurate. Moreover, the evaluation is not limited to the capacity of the lithium battery pack, but also takes into account the risk assessment value of the lithium battery, and makes a comprehensive judgment. Therefore, the loss degree assessment value of the lithium battery pack obtained can more accurately reflect the loss of the lithium battery pack, and is more practical. Moreover, after the test, a comprehensive score is given to the batch of lithium batteries, which can help relevant managers intuitively understand the quality of the batch of lithium batteries and help relevant managers to make corresponding rectifications. The use effect is good and has a good prospect for use. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 This is a system block diagram of a lithium-ion battery high temperature cycle aging test control system of the present invention;

[0065] Figure 2 This is a flow chart of a lithium-ion battery high temperature cycle aging test control system of the present invention;

[0066] Figure 3 The present invention is a flow chart of a lithium-ion battery high-temperature cycle aging test control method. DETAILED DESCRIPTION

[0067] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0068] Example 1: Please refer to Figure 1 , this embodiment provides a lithium-ion battery high temperature cycle aging test control system, including a preliminary detection module, an aging test module, a risk control module, an aging assessment module and a risk assessment model.

[0069] Lithium battery pack construction

[0070] A lithium battery pack is composed of several lithium batteries. In actual use, the lithium batteries are all made of lithium batteries that have passed the inspection. In order to reduce the inspection steps of lithium batteries, a high-temperature cycle aging test is directly carried out. The high-temperature cycle aging test data is used to judge the lithium batteries. The high-temperature cycle aging test data is used to judge the lithium batteries based on the preliminary inspection module.

[0071] The preliminary detection module obtains the high-temperature cycle loss test data of Z lithium batteries produced in the same batch, calculates the capacity loss rate of all lithium batteries, and compares the capacity loss rate of the lithium batteries with the preset standard threshold range, removes the lithium batteries that do not meet the standard threshold range, and randomly selects A lithium batteries from the lithium batteries that meet the standard threshold to build a lithium battery pack;

[0072] The high temperature cycle loss test data of lithium batteries are the initial capacity of lithium batteries and the capacity data after 5 consecutive charge and discharge cycles at 60°C. The discharge process is to discharge at a constant current of 1C from the upper limit voltage (i.e. the current is ) to the termination voltage, and the charging process is from the termination voltage to a constant current of 1C (i.e., the current is ) to the upper limit voltage, and then charge at a constant voltage until the charging current decreases to 0.05C (i.e. the current is );

[0073] The calculation formula of capacity loss rate is as follows:

[0074]

[0075] In the formula, is the capacity loss rate of lithium battery, It is the capacity of lithium battery after high temperature cycle aging test. is the initial capacity of the lithium battery.

[0076] The preset standard threshold range is ,in is the average value of the capacity loss rate of several lithium batteries produced in the same batch. .

[0077] For example, one thousand lithium batteries (upper limit voltage is 3.6V, and termination voltage is 2.8V) are produced in the same batch. Ten lithium batteries are randomly selected for high temperature cycle loss test. The capacity of each lithium battery is measured after five high temperature cycle loss tests according to the above steps, and the capacity loss rate is calculated. The specific results are as follows:

[0078]

[0079] Among them, No. 3, No. 4, and No. 10 did not meet the requirements and were eliminated, and then 6 lithium batteries were randomly selected from the remaining 7 lithium batteries and connected in parallel to construct a lithium battery pack (most vehicle batteries are lithium batteries connected in parallel to form a lithium battery pack, and then multiple lithium battery packs are connected in series to form the entire vehicle battery).

[0080] The experimental data comes from a parallel lithium battery pack constructed with 6 lithium batteries. The number of extractions can also be increased and connected in series to form a similar vehicle battery structure.

[0081] Before the high-temperature cycle aging test, the lithium batteries are pre-tested to screen out abnormal lithium batteries, and then the qualified lithium batteries after screening are used to build a lithium battery pack. The lithium battery pack is used for testing. The test results are more in line with the actual situation and the data obtained are more standardized. In addition, this step can reduce the impact of battery differences in the lithium battery pack, effectively reduce the risk of the high-temperature cycle aging test, and improve the safety of the high-temperature cycle aging test.

[0082] Aging test

[0083] After obtaining the lithium battery pack that needs to be tested, the obtained lithium battery pack is formally tested. During the test, the lithium battery pack is placed in a constant temperature box (the model of the constant temperature box is DHG-9023A), and the temperature is measured by the thermocouple in contact with the surface of the lithium battery pack in the constant temperature container, and the battery temperature is recorded with a temperature scanner (the model of the temperature scanner is 34970A). The battery charge and discharge test equipment (model BTS-M) is used for stable charging and discharging, and multiple groups of industrial cameras (model KB-85A) are installed at fixed points for shooting. A hydrogen sensor (model H2SCANHY-OPTIMA) and a carbon dioxide sensor (model GMP251 / GMP252) are installed inside the battery charge and discharge test equipment.

[0084] The above-mentioned equipment is uniformly controlled by the aging test module. The aging test module performs N times of charge and discharge tests at a set temperature according to the set charge and discharge strategy, and collects the working data of the lithium battery pack in the high-temperature cycle aging test and the data of the lithium battery pack after the high-temperature cycle aging test in real time.

[0085] The steps for the aging test module to perform charge and discharge tests are as follows:

[0086] S1, discharge test: at 55℃ environment, the upper limit voltage is 1C (i.e. the current is )Discharge at constant current to the termination voltage and leave it for 20 minutes;

[0087] S2. Charging test: At 55℃, the battery is charged at 1C (i.e., the current is ) constant current charge to the upper limit voltage, and then constant voltage charge until the charging current decreases to 0.05C (i.e. the current is ), leave it for 20 minutes, count once, count the counting result and compare it with N. When the counting result is less than N, repeat S1. When the counting result is equal to N, aging test is suspended.

[0088] The total number of measurements of lithium battery pack is When N is 30, the total number of measurements of the lithium battery pack is , N is 20, the total number of measurements of the lithium battery pack is When the total number of measurements of the lithium battery pack is greater than 500, N is 10.

[0089] Because the lithium battery pack will experience wear after each test, the existing measurement at 25°C shows that the normal use of lithium batteries is more than 2000 times, so the test is conducted every 50 times. However, at high temperatures, the wear will increase, so the number of intervals needs to be reduced. Moreover, after reaching a certain level, in a high temperature environment, the battery will heat up severely and the wear will be further accelerated. Therefore, the number of intervals needs to be further reduced.

[0090] N can also be set according to the loss degree assessment value Shpg calculated by the aging assessment module. For example, statistical data is collected to obtain the loss value corresponding to 400 tests. When the loss value does not reach the loss value, the test is performed every 30 times. After reaching the loss value, the test is performed every 10 times.

[0091] N is set according to the manufacturer's requirements.

[0092] The remaining capacity of the lithium battery pack composed of the above 6 groups of lithium batteries after the aging test module test times is shown in the following table:

[0093]

[0094] The above data are based on the existing capacity loss rate as the termination condition of the aging test. The capacity loss rate can also be used as a termination condition of 80%, and the corresponding number of times is 450 times.

[0095] Test control

[0096] During the test, affected by high temperature, even small defects in the production of lithium battery packs may cause major accidents, so corresponding risk management is needed. The risk management module obtains the working data of the lithium battery pack under the high-temperature cycle aging test in real time, and builds a risk assessment model to predict the risk assessment value Fxpg of the battery during the high-temperature cycle aging test, and compares the risk assessment value with the preset safety warning threshold, and chooses whether to interrupt the aging test module based on the comparison results.

[0097] The working data in the high-temperature cycle aging test of the lithium battery pack include the battery deformation (collected by an industrial camera, processed by a computer, and the degree of deformation is determined by the proportion of pixels in the picture occupied by the lithium battery. The pictures taken by multiple groups of industrial cameras are processed and the average value is taken after removing the maximum and minimum values), the battery surface temperature (collected directly by thermocouples), the hydrogen content (collected by hydrogen sensors) and the carbon dioxide content (collected by carbon dioxide sensors). The data after the high-temperature cycle aging test of the lithium battery pack includes the capacity of all lithium batteries in the lithium battery pack (the battery capacity data is obtained directly through the discharge data of the discharge test).

[0098] The process of the risk assessment model is as follows:

[0099] Real-time extraction of the working data of the lithium battery pack during the high-temperature cycle aging test, and recording the time point corresponding to the working data;

[0100] The risk assessment value Fxpg of the lithium battery pack during the high temperature cycle aging test is predicted based on the extracted data and the corresponding time. The specific calculation formula is as follows:

[0101]

[0102] In the formula, is the risk assessment value of the lithium battery pack during the nth test, is the calculated risk assessment value caused by temperature, is the battery deformation at the nth detection, is the influence coefficient of the risk assessment value corresponding to the battery deformation, is the hydrogen content at the nth detection, is the hydrogen content in the air, is the influence coefficient of the risk assessment value corresponding to hydrogen, is the carbon dioxide content at the nth detection, is the carbon dioxide content in the air, is the impact coefficient of the risk assessment value corresponding to carbon dioxide;

[0103] is the surface temperature of the lithium battery pack during the nth detection, is the surface temperature of the lithium battery pack during the n-1th detection, is the influence coefficient of instantaneous temperature change on risk assessment value, is the influence coefficient of temperature on risk assessment value, It is the interval time between the n-1th detection time point and the nth detection time point.

[0104] Different lithium batteries have different requirements for their shells, etc., so the corresponding influence coefficients are different.

[0105] The obvious changes in hydrogen and carbon dioxide are mainly caused by leakage, which means that there are obvious loopholes in the battery. Therefore, the corresponding impact coefficient is large. In addition, the hydrogen content in the air is almost unchanged, while carbon dioxide has certain fluctuations. Therefore, the impact coefficient corresponding to hydrogen is greater than that of carbon dioxide. The slight deformation of the battery does not affect the operation of the battery, so its corresponding impact coefficient is small. The sudden change in temperature is mainly caused by abnormality in the battery, so its corresponding impact coefficient is greater than the total temperature impact coefficient.

[0106] The preset safety warning thresholds include a warning threshold Jsyz and an interruption threshold Zdyz, and Zdyz>Jsyz;

[0107] After comparing the risk assessment value with the preset safety warning threshold:

[0108] If the risk assessment value < warning threshold Jsyz, it means that the risk level of lithium battery is low, the aging test is carried out normally, and the risk control module does not respond;

[0109] For example, the warning threshold Jsyz is 70, and the interruption threshold Zdyz is 80. When the calculated risk assessment value is less than 70, the risk control module does not respond.

[0110] If the warning threshold Jsyz ≤ risk assessment value < interruption threshold Zdyz, it means that the risk level of lithium batteries is high, and the risk control module issues a first-level warning and implements the detection cycle adjustment strategy;

[0111] For example, the warning threshold Jsyz is 70, and the interruption threshold Zdyz is 80. When the calculated risk assessment value is between 70 and 80, the risk management module controls the corresponding warning equipment (sound and light alarm) to issue a first-level alarm to alert the staff.

[0112] If the interruption threshold Zdyz ≤ risk assessment value , it means that the risk level of lithium battery is high, the risk control module issues a secondary warning and interrupts the aging test;

[0113] For example, the warning threshold Jsyz is 70, and the interruption threshold Zdyz is 80. When the calculated risk assessment value is greater than 80, the risk control module controls the corresponding warning device (sound and light alarm) to issue a secondary alarm (with different frequencies of sound and light), alerts the staff, controls the battery charging and discharging test equipment to disconnect from the lithium battery pack, and at the same time, the constant temperature box stops heating.

[0114] The detection cycle adjustment strategy is implemented to shorten the interval time for collecting working data, and the formula based on it is as follows;

[0115]

[0116] In the formula, is the interval between the n-1th detection time point and the nth detection time point, is the risk assessment value at the n-1th detection, Risk Assessment Value <The interval between adjacent detection time points when the warning threshold Jsyz is is the floor function.

[0117] When the risk is closer to the interruption threshold Zdyz, it may fail at any time, so the detection time needs to be shortened. As it approaches the interruption threshold, the reduction factor increases, and the overall form is exponential. The above formula is the optimal data collection interval obtained after collecting 30 abnormal data through computer simulation.

[0118] During the high-temperature cycle aging test of the lithium-ion group, the working data of the lithium battery group is collected in real time, and the working data of the lithium battery group is further analyzed to obtain the risk assessment value of the lithium battery group, and the obtained risk assessment value of the lithium battery group is compared with the set safety warning threshold in real time, and the suddenness of the abnormality is comprehensively considered. When the risk assessment value is higher, the detection frequency is increased, which can ensure that the abnormality of the lithium battery pack is monitored at the first time, and the high-temperature cycle aging test is interrupted in time, so as to ensure the safety of related equipment and effectively reduce risks. At the same time, it can ensure the integrity of the test data, with good use effect and good use prospects.

[0119] Test Evaluation

[0120] During the high-temperature cycle aging test, it is necessary to collect data from the lithium battery pack at a certain interval to determine whether the test needs to continue. This process is based on the aging assessment module.

[0121] The aging assessment module obtains the lithium battery parameter data and risk assessment value Fxpg of the lithium battery pack after the high-temperature cycle aging test in real time, and constructs an aging assessment model to calculate the loss degree assessment value Shpg of the lithium battery pack, and compares the loss degree assessment value with the preset battery loss threshold. According to the comparison result, it is decided whether to start the aging test module for retesting.

[0122] The calculation formula for calculating the loss evaluation value Shpg of the lithium battery pack is as follows:

[0123]

[0124] In the formula, , , , These are the data detected and calculated during the previous aging test corresponding to the loss evaluation value Shpg of the lithium battery pack. The number of times the working data under the high temperature cycle aging test was collected during the previous aging test corresponding to the loss degree evaluation value Shpg of the lithium battery pack, is the risk assessment value of the lithium battery pack during the i-th detection, is the risk assessment value of the lithium battery pack during the i-1th test, is the capacity of the i-th lithium battery after high temperature cycle aging test, is the initial capacity of the lithium battery, , is the preset proportional coefficient;

[0125] After comparing the loss degree assessment value Shpg of the lithium battery pack with the preset battery loss threshold Shyz;

[0126] If Shpg<Shyz, start the aging test module;

[0127] If Shpg≥Shyz, turn off the aging test module and the test ends.

[0128] After the test is finished, the test data is collected.

[0129] The loss evaluation value Shpg corresponding to the number of tests of the aging test module for the lithium battery pack composed of the above 6 groups of lithium batteries is shown in the following table:

[0130]

[0131] The calculated loss degree assessment value Shpg is slightly higher than the capacity loss because it superimposes the working data of the lithium battery pack (changes in internal resistance, etc. or from the temperature aspect). Taking various aspects into comprehensive consideration, the calculated loss degree assessment value Shpg is more accurate than the capacity loss. The loss degree assessment value Shpg has a better evaluation effect and a more intuitive response.

[0132] Production Evaluation

[0133] After testing the lithium battery pack, the lithium battery pack and the entire batch of lithium batteries are evaluated. The evaluation is based on a comprehensive evaluation module. The comprehensive evaluation module obtains the total number of tests Cssj of the aging test module and calculates the high temperature cycle test data of the lithium ion group. The high temperature cycle test data is Cssj-N. The batch of lithium battery packs is rated according to the high temperature cycle test data of the lithium ion group, and the lithium battery packs produced in the batch are comprehensively scored.

[0134] When the high temperature cycle test data of the lithium battery pack is less than 250 times, the lithium battery pack is rated as level three;

[0135] When the high temperature cycle test data of the lithium battery pack is 250-500 times, the lithium battery pack is rated as Level 2;

[0136] When the high temperature cycle test data of the lithium battery pack is more than 500 times, the lithium battery pack is rated as level one;

[0137] The calculation formula for the comprehensive score of lithium batteries produced in this batch is as follows:

[0138]

[0139] In the formula, Provide a comprehensive score for the lithium batteries produced in this batch. The score corresponding to the lithium battery pack rating, For the number of lithium batteries eliminated, the corresponding score for a lithium battery pack rated level 3 is 60 points, the corresponding score for a lithium battery pack rated level 2 is 80 points, and the corresponding score for a lithium battery pack rated level 1 is 100 points.

[0140] For example, in the above test data, the comprehensive score corresponding to this batch of lithium batteries is point.

[0141] When the score is lower than 60 points, the production process can be changed. The effect of the change can be judged by the difference in the comprehensive scores of the lithium batteries produced in the batches after the change, which makes it easier for management personnel to supervise.

[0142] The entire process of the high-temperature cycle aging test is divided into multiple stages. As the number of tests increases, the number of loss assessments of the lithium battery pack is gradually increased. Compared with the existing method of using a fixed test of 50 times per test, a more accurate number of lithium battery uses can be obtained, and the data obtained is more accurate. Moreover, the evaluation is not limited to the capacity of the lithium battery pack, but also takes into account the risk assessment value of the lithium battery, and makes a comprehensive judgment. Therefore, the loss degree assessment value of the lithium battery pack obtained can more accurately reflect the loss of the lithium battery pack, and is more practical. Moreover, after the test, a comprehensive score is given to the batch of lithium batteries, which can help relevant managers intuitively understand the quality of the batch of lithium batteries and help relevant managers to make corresponding rectifications. The use effect is good and has a good prospect for use.

[0143] The lithium-ion battery high temperature cycle aging test control system controls the lithium battery from the source and comprehensively supervises the lithium battery pack during the test, which can greatly improve the safety of the lithium battery pack test process.

[0144] Example 2: Please refer to Figure 3Based on Example 1, a lithium-ion battery high temperature cycle aging test control method comprises the following steps:

[0145] Step 1: Obtain high temperature cycle loss test data of Z lithium batteries produced in the same batch, calculate the capacity loss rate of all lithium batteries, and compare the capacity loss rate of the lithium batteries with a preset standard threshold range, remove the lithium batteries that do not meet the standard threshold range, and randomly select A lithium batteries from the lithium batteries that meet the standard threshold to construct a lithium battery pack;

[0146] Step 2: Control the aging test equipment to perform N times of charge and discharge tests at a set temperature according to a set charge and discharge strategy, and collect the working data of the lithium battery pack in the high-temperature cycle aging test and the data of the lithium battery pack after the high-temperature cycle aging test in real time;

[0147] Step 3: Obtain the working data of the lithium battery pack under the high temperature cycle aging test in real time, and build a risk assessment model to predict the risk assessment value Fxpg of the battery during the high temperature cycle aging test, and compare the risk assessment value with the preset safety warning threshold, and choose whether to interrupt the aging test according to the comparison result;

[0148] The security warning threshold includes the warning threshold Jsyz and the interruption threshold Zdyz;

[0149] If the risk assessment value < warning threshold Jsyz, it means the risk level of lithium battery is low and the aging test is carried out normally;

[0150] If the warning threshold Jsyz ≤ risk assessment value < interruption threshold Zdyz, it means that the risk level of lithium battery is high, a first-level warning is issued, and the detection cycle adjustment strategy is implemented;

[0151] If the interruption threshold Zdyz ≤ risk assessment value , it means that the risk level of lithium battery is high, a second-level warning is issued, and the aging test is interrupted;

[0152] Step 4: Obtain the lithium battery parameter data and risk assessment value Fxpg of the lithium battery pack after the high-temperature cycle aging test in real time, and build an aging assessment model to calculate the loss degree assessment value Shpg of the lithium battery pack, and compare the loss degree assessment value with the preset battery loss threshold, and choose whether to start the aging test for retesting according to the comparison result;

[0153] After comparing the loss degree assessment value Shpg of the lithium battery pack with the preset battery loss threshold Shyz;

[0154] If Shpg<Shyz, start the aging test;

[0155] If Shpg ≥ Shyz, the aging test is turned off and the test ends.

[0156] Step 5: Obtain the total number of tests Cssj, and calculate the high temperature cycle test data Cssj-N of the lithium ion battery pack, rate the batch of lithium battery packs according to the high temperature cycle test data, and give a comprehensive score to the lithium battery packs produced in the batch.

[0157] In the application, the several formulas involved are all calculated by removing the dimensions and taking their numerical values. The formula is a formula obtained by collecting a large amount of data and performing software simulation to obtain the most recent real situation. The formula is set by technical personnel in this field according to actual conditions.

[0158] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination thereof. When implemented using software, the above embodiments may be implemented in whole or in part in the form of a computer program product. A person of ordinary skill in the art may appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein may be implemented in electronic hardware, or in a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution.

[0159] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, and may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0160] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A lithium-ion battery high temperature cycle aging test control system, characterized in that: include: The preliminary detection module obtains the high-temperature cycle loss test data of Z lithium batteries produced in the same batch, calculates the capacity loss rate of all lithium batteries, and compares the capacity loss rate of the lithium batteries with the preset standard threshold range, removes the lithium batteries that do not meet the standard threshold range, and randomly selects A lithium batteries from the lithium batteries that meet the standard threshold to build a lithium battery pack; The aging test module performs N times of charge and discharge tests at a set temperature according to the set charge and discharge strategy, and collects the working data of the lithium battery pack in the high-temperature cycle aging test and the data of the lithium battery pack after the high-temperature cycle aging test in real time; The risk control module obtains the working data of the lithium battery pack under the high-temperature cycle aging test in real time, and builds a risk assessment model to predict the risk assessment value Fxpg of the battery during the high-temperature cycle aging test, and compares the risk assessment value with the preset safety warning threshold, and chooses whether to interrupt the aging test module based on the comparison result; The prediction process of the risk assessment model is as follows: Real-time extraction of the working data of the lithium battery pack during the high-temperature cycle aging test, and recording the time point corresponding to the working data; The risk assessment value Fxpg of the lithium battery pack during the high temperature cycle aging test is predicted based on the extracted data and the corresponding time. The specific calculation formula is as follows: ， In the formula, is the risk assessment value of the lithium battery pack during the nth test, is the calculated risk assessment value caused by temperature, is the battery deformation at the nth detection, is the influence coefficient of the risk assessment value corresponding to the battery deformation, is the hydrogen content at the nth detection, is the hydrogen content in the air, is the influence coefficient of the risk assessment value corresponding to hydrogen, is the carbon dioxide content at the nth detection, is the carbon dioxide content in the air, is the impact coefficient of the risk assessment value corresponding to carbon dioxide; is the surface temperature of the lithium battery pack during the nth detection, is the surface temperature of the lithium battery pack during the n-1th detection, is the influence coefficient of instantaneous temperature change on risk assessment value, is the influence coefficient of temperature on risk assessment value, is the interval between the n-1th detection time point and the nth detection time point; The aging assessment module obtains the lithium battery parameter data and risk assessment value Fxpg of the lithium battery pack after the high-temperature cycle aging test in real time, and builds an aging assessment model to calculate the loss degree assessment value Shpg of the lithium battery pack, and compares the loss degree assessment value with the preset battery loss threshold. According to the comparison result, it is decided whether to start the aging test module for retesting.

2. A lithium-ion battery high temperature cycle aging test control system according to claim 1, characterized in that: The high temperature cycle loss test data of the lithium battery is the initial power of the lithium battery and the power data after 5 consecutive charge and discharge at 60°C. The discharge process is to discharge from the upper limit voltage at a constant current of 1C to the termination voltage, and the charging process is to charge from the termination voltage at a constant current of 1C to the upper limit voltage, and then charge at a constant voltage until the charging current is reduced to 0.05C. The calculation formula of capacity loss rate is as follows: ， In the formula, is the capacity loss rate of lithium battery, It is the capacity of lithium battery after high temperature cycle aging test. is the initial capacity of the lithium battery.

3. A lithium-ion battery high temperature cycle aging test control system according to claim 2, characterized in that: The preset standard threshold range is ,in is the average value of the capacity loss rate of several lithium batteries produced in the same batch. .

4. A lithium-ion battery high temperature cycle aging test control system according to claim 3, characterized in that: The steps for the aging test module to perform charge and discharge tests are as follows: S1. Discharge test: Discharge from the upper limit voltage to the end voltage at 1C constant current at 55℃ and leave for 20 minutes; S2, charging test: at 55℃, charge at 1C constant current to the upper limit voltage, then charge at constant voltage until the charging current decreases to 0.05C, leave for 20 minutes, count once, count the result and compare it with N. When the result is less than N, repeat S1. When the result is equal to N, suspend the aging test. The total number of measurements of lithium battery pack is When N is 30, the total number of measurements of the lithium battery pack is , N is 20, the total number of measurements of the lithium battery pack is When the total number of measurements of the lithium battery pack is greater than 500, N is 10.

5. A lithium-ion battery high temperature cycle aging test control system according to claim 4, characterized in that: The working data in the high temperature cycle aging test of the lithium battery pack includes the battery deformation, battery surface temperature, hydrogen content and carbon dioxide content. The data after the high temperature cycle aging test of the lithium battery pack includes the capacity of all lithium batteries in the lithium battery pack.

6. A lithium-ion battery high temperature cycle aging test control system according to claim 5, characterized in that: The preset safety warning thresholds include a warning threshold Jsyz and an interruption threshold Zdyz, and Zdyz>Jsyz; After comparing the risk assessment value with the preset safety warning threshold: If the risk assessment value < warning threshold Jsyz, it means that the risk level of lithium battery is low, the aging test is carried out normally, and the risk control module does not respond; If the warning threshold Jsyz ≤ risk assessment value < interruption threshold Zdyz, it means that the risk level of lithium batteries is high, and the risk control module issues a first-level warning and implements the detection cycle adjustment strategy; If the interruption threshold Zdyz ≤ risk assessment value , it means that the risk level of lithium battery is high, the risk control module issues a second-level warning and interrupts the aging test; The detection cycle adjustment strategy is implemented to shorten the interval time for collecting working data, and the formula based on it is as follows; ， In the formula, is the interval between the n-1th detection time point and the nth detection time point, is the risk assessment value at the n-1th detection, Risk Assessment Value <The interval between adjacent detection time points when the warning threshold Jsyz is is the floor function.

7. A lithium-ion battery high temperature cycle aging test control system according to claim 6, characterized in that: The calculation formula for calculating the loss evaluation value Shpg of the lithium battery pack is as follows: ， In the formula, , , , These are the data detected and calculated during the previous aging test corresponding to the loss evaluation value Shpg of the lithium battery pack. The number of times the working data under the high temperature cycle aging test was collected during the previous aging test corresponding to the loss degree evaluation value Shpg of the lithium battery pack, is the risk assessment value of the lithium battery pack during the i-th detection, is the risk assessment value of the lithium battery pack during the i-1th test, is the capacity of the i-th lithium battery after high temperature cycle aging test, is the initial capacity of the lithium battery, , is the preset proportional coefficient; After comparing the loss degree assessment value Shpg of the lithium battery pack with the preset battery loss threshold Shyz; If Shpg<Shyz, start the aging test module; If Shpg≥Shyz, turn off the aging test module and the test ends.

8. A lithium-ion battery high temperature cycle aging test control system according to claim 7, characterized in that: It also includes a comprehensive evaluation module, which obtains the total number of tests Cssj of the aging test module and calculates the high temperature cycle test data of the lithium ion group, the high temperature cycle test data is Cssj-N, and rates the batch of lithium battery packs according to the high temperature cycle test data of the lithium ion group, and gives a comprehensive score to the lithium battery packs produced in the batch; When the high temperature cycle test data of the lithium battery pack is less than 250 times, the lithium battery pack is rated as level three; When the high temperature cycle test data of the lithium battery pack is 250-500 times, the lithium battery pack is rated as Level 2; When the high temperature cycle test data of the lithium battery pack is more than 500 times, the lithium battery pack is rated as level one; The calculation formula for the comprehensive score of lithium batteries produced in this batch is as follows: ， In the formula, Provide a comprehensive score for the lithium batteries produced in this batch. The score corresponding to the lithium battery pack rating, For the number of lithium batteries eliminated, the corresponding score for a lithium battery pack rated level 3 is 60 points, the corresponding score for a lithium battery pack rated level 2 is 80 points, and the corresponding score for a lithium battery pack rated level 1 is 100 points.

9. A lithium-ion battery high temperature cycle aging test control method, using any system described in claim 1 to 8, characterized in that: The steps include: Step 1: Obtain high temperature cycle loss test data of Z lithium batteries produced in the same batch, calculate the capacity loss rate of all lithium batteries, and compare the capacity loss rate of the lithium batteries with a preset standard threshold range, remove the lithium batteries that do not meet the standard threshold range, and randomly select A lithium batteries from the lithium batteries that meet the standard threshold to construct a lithium battery pack; Step 2: Control the aging test equipment to perform N times of charge and discharge tests at a set temperature according to a set charge and discharge strategy, and collect the working data of the lithium battery pack in the high-temperature cycle aging test and the data of the lithium battery pack after the high-temperature cycle aging test in real time; Step 3: Obtain the working data of the lithium battery pack under the high temperature cycle aging test in real time, and build a risk assessment model to predict the risk assessment value Fxpg of the battery during the high temperature cycle aging test, and compare the risk assessment value with the preset safety warning threshold, and choose whether to interrupt the aging test according to the comparison result; Step 4: Obtain the lithium battery parameter data and risk assessment value Fxpg of the lithium battery pack after the high-temperature cycle aging test in real time, and build an aging assessment model to calculate the loss degree assessment value Shpg of the lithium battery pack, and compare the loss degree assessment value with the preset battery loss threshold, and choose whether to start the aging test for retesting according to the comparison result; Step 5: Obtain the total number of tests Cssj, and calculate the high temperature cycle test data Cssj-N of the lithium ion battery pack, rate the batch of lithium battery packs according to the high temperature cycle test data, and give a comprehensive score to the lithium battery packs produced in the batch.

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