Battery cell water content determination method and device, electronic equipment, readable storage medium and program product

Abstract

The invention provides a method and a device for determining the water content of a battery cell, electronic equipment, a readable storage medium and a program product. A specific implementation mode of the method comprises the following steps: acquiring an insulation resistance measured value of a to-be-measured battery cell; obtaining an actually measured state value of a cell water resistance influence factor, wherein the cell water resistance influence factor is a factor influencing the relationship between the water content and the insulation resistance value of the cell; and according to the insulation resistance measured value and the measured state value of the cell water resistance influence factor, determining the water content condition of the to-be-measured cell. The method can improve the accuracy of the determined water content condition.

Description

Technical Field

[0001] The present application relates to the field of battery cell detection, and specifically, to a method, device, electronic device, readable storage medium, and program product for determining the water content of a battery cell. Background Art

[0002] During the production process of battery cells, the battery cells are usually baked. After baking, the moisture content of the electrodes in the battery cells is determined to screen out battery cells with qualified moisture content, thereby improving the safety and performance of the battery cells.

[0003] In the related art, the water content of the battery cell is usually determined manually, and the error of the water content obtained in this way is large, which reduces the safety and performance of the battery cell. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a method, device, electronic device, readable storage medium, and program product for determining the water content of a battery cell, so as to improve the accuracy of the determined water content.

[0005] In the first aspect, an embodiment of the present application provides a method for determining the water content of a battery cell, the method comprising: obtaining the measured value of the insulation resistance of the battery cell to be tested; obtaining the measured state value of the water resistance influencing factor of the battery cell, the water resistance influencing factor of the battery cell being a factor that affects the relationship between the water content and the insulation resistance value of the battery cell; the water resistance influencing factor of the battery cell comprises one or more of the following: ambient humidity, measurement voltage, battery cell temperature, SOC of the battery cell; according to the measured value of the insulation resistance and the measured state value of the water resistance influencing factor of the battery cell, the water content of the battery cell to be tested is determined. In this way, there is no need to disassemble the battery cell, nor to meet the strict requirements that need to be met after disassembly, so the error of the determined water content can be reduced and the accuracy can be improved. Moreover, the operation process is simplified, the production efficiency is improved, and the manufacturing cost is reduced. In addition, the influence of the water resistance influencing factor of the battery cell on the relationship between the water content and the insulation resistance value of the battery cell is further taken into consideration. Therefore, the water content of the battery cell to be tested is determined by combining the actual measured value of the insulation resistance and the measured state value of the water resistance influencing factor of the battery cell, which can further reduce the error of the water content and improve the accuracy.

[0006] Optionally, the determination of the water content of the battery cell to be tested based on the measured insulation resistance value and the measured state value of the battery cell water resistance influencing factor includes: determining the target insulation resistance reference threshold of the battery cell water resistance influencing factor at the measured state value based on the calibrated insulation resistance reference threshold of the battery cell water resistance influencing factor at different state values; and determining the water content of the battery cell to be tested based on the measured insulation resistance value and the target insulation resistance reference threshold. In this way, a more accurate target insulation resistance reference threshold can be obtained based on the pre-calibrated insulation resistance reference threshold, so that when the water content of the battery cell to be tested is determined based on the target insulation resistance reference threshold, the accuracy of the determination result can be improved.

[0007] Optionally, the target insulation resistance reference threshold value of the cell water resistance influencing factor at the measured state value is determined according to the insulation resistance reference threshold value of the cell water resistance influencing factor at different state values, including: determining the target insulation resistance reference threshold value using a preset interpolation algorithm according to the insulation resistance reference threshold value of the cell water resistance influencing factor at different state values ​​calibrated. In this way, the target insulation resistance reference threshold value can be determined using a preset interpolation algorithm, which reduces the calibration workload to a certain extent, improves the determination efficiency and the accuracy of the target insulation resistance reference threshold value.

[0008] Optionally, the target insulation resistance reference threshold of the cell water resistance influencing factor at the measured state value is determined according to the insulation resistance reference threshold of the cell water resistance influencing factor at different state values, including: obtaining a fitting relationship between the state value and the insulation resistance reference threshold according to the insulation resistance reference threshold of the cell water resistance influencing factor at different state values; and determining the target insulation resistance reference threshold at the measured state value based on the fitting relationship. In this way, determining the target insulation resistance reference threshold through the fitting relationship also reduces the calibration workload to a certain extent, improves the determination efficiency and the accuracy of the target insulation resistance reference threshold.

[0009] Optionally, the target insulation resistance reference threshold of the cell water resistance influencing factor at the measured state value is determined according to the calibrated insulation resistance reference threshold of the cell water resistance influencing factor at different state values, including: inputting the measured state value into a prediction model to obtain the target insulation resistance reference threshold; the prediction model is trained based on the insulation resistance reference threshold of the cell water resistance influencing factor at different state values. In this way, the target insulation resistance reference threshold can be obtained with the help of the prediction model, which is trained based on the insulation resistance reference threshold of the cell water resistance influencing factor at different state values ​​calibrated in advance. Therefore, when facing the measured state value, a more accurate target insulation resistance reference threshold can be obtained.

[0010] Optionally, the determining the water content of the battery cell to be tested according to the insulation resistance measured value and the target insulation resistance reference threshold value includes: determining a first resistance change between the insulation resistance measured value corresponding to the first measured state value and the insulation resistance measured value corresponding to the second measured state value; determining a second resistance change between the target insulation resistance reference threshold value corresponding to the first measured state value and the target insulation resistance reference threshold value corresponding to the second measured state value; and determining the water content of the battery cell to be tested according to the first resistance change and the second resistance change. In this way, the water content of the battery cell to be tested can be determined more accurately through the insulation resistance value change caused by the measured state values ​​with the same change.

[0011] Optionally, after determining the water content of the battery cell to be tested according to the measured value of the insulation resistance and the measured state value of the water resistance influencing factor of the battery cell, the method further includes: obtaining multiple insulation resistance reference values ​​corresponding to the measured state values ​​of the calibrated battery cell at different water contents; comparing the multiple insulation resistance reference values ​​with the measured value of the insulation resistance respectively to determine the insulation resistance reference value with the smallest resistance difference; determining the water content of the battery cell to be tested according to the water content corresponding to the insulation resistance reference value with the smallest resistance difference. In this way, the specific water content of the battery cell to be tested can be obtained, which is convenient for determining the baking strategy based on the specific water content in the future, so as to improve the baking efficiency and obtain a battery cell with qualified water content.

[0012] In the second aspect, the embodiment of the present application provides a device for determining the water content of a battery cell, the device comprising: a first acquisition module for obtaining the measured value of the insulation resistance of the battery cell to be tested; a second acquisition module for obtaining the measured state value of the water resistance influencing factor of the battery cell, the water resistance influencing factor of the battery cell is a factor that affects the relationship between the water content and the insulation resistance value of the battery cell; the water resistance influencing factor of the battery cell includes one or more of the following: ambient humidity, measurement voltage, battery cell temperature, SOC of the battery cell; a determination module for determining the water content of the battery cell to be tested based on the measured value of the insulation resistance and the measured state value of the water resistance influencing factor of the battery cell. In this way, there is no need to disassemble the battery cell, nor to meet the strict requirements that need to be met after disassembly, so the error of the determined water content can be reduced and the accuracy can be improved. Moreover, the operation process is simplified, the production efficiency is improved, and the manufacturing cost is reduced. In addition, the influence of the water resistance influencing factor of the battery cell on the relationship between the water content and the insulation resistance value of the battery cell is further taken into consideration. Therefore, the water content of the battery cell to be tested is determined by combining the actual measured value of the insulation resistance and the measured state value of the water resistance influencing factor of the battery cell, which can further reduce the error of the water content and improve the accuracy.

[0013] In a third aspect, an embodiment of the present application provides an electronic device, comprising a processor and a memory, wherein the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the processor, the steps in the method provided in the first aspect are performed.

[0014] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps in the method provided in the first aspect are performed.

[0015] In a fifth aspect, an embodiment of the present application provides a computer program product, which includes a computer program or instructions, and when the computer program or instructions are executed by a processor, the method described in the first aspect is performed.

[0016] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or understood by practicing the embodiments of the present application. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the written description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A flow chart of a method for determining water content of a battery cell provided in an embodiment of the present application; Figure 2 An insulation resistance value-water content relationship diagram provided in an embodiment of the present application; Figure 3 A test result diagram for determining the moisture content by the insulation resistance value provided in an embodiment of the present application; Figure 4 A battery core temperature-insulation resistance value relationship diagram provided in an embodiment of the present application; Figure 5 A test result diagram for determining the water content by the insulation resistance value when considering the temperature factor of the battery cell provided in an embodiment of the present application; Figure 6 A structural block diagram of a device for determining water content of a battery cell provided in an embodiment of the present application; Figure 7 A schematic diagram of the structure of an electronic device for executing a method for determining water content in a battery cell provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0020] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0021] It should be noted that the embodiments in this application or the technical features in the embodiments may be combined if there is no conflict.

[0022] In the related art, the water content of the battery cell is usually determined manually, so the error of the water content obtained is large, which reduces the safety and performance of the battery cell. Specifically, the operator will make a sample battery cell in advance, and then determine the water content of the sample battery cell to obtain a water content reference value. Then, after the battery cell is baked, the battery cell is disassembled to take out the pole piece, and then the water content in the pole piece is determined, and the water content is compared with the obtained water content reference value. If it is greater than the water content reference value, it can be regarded as the water content of the battery cell is unqualified, and if it is less than the water content reference value, it can be regarded as the water content of the battery cell is qualified. Further, in the determination process of the operator, the production workshop needs to meet the temperature and humidity requirements, and the operator needs to operate strictly in accordance with the relevant operation requirements (such as disassembly / assembly requirements). The probability of not meeting the temperature and humidity requirements and the operation requirements is high, which easily leads to a large error in the determined water content. In addition, the operator can use the Karl Fischer method to determine the water content of the sample battery cell to obtain a water content reference value, but since the process of obtaining the water content reference value also needs to meet the above-mentioned temperature and humidity requirements and operation requirements, the error of the water content reference value is also large. Therefore, the error of the water content of the battery cell determined manually is large.

[0023] In addition, the above-mentioned method of manually determining the water content of the battery cell requires suspending the production process of the battery cell (i.e., suspending it after baking), and continuing the production process only after obtaining the battery cell with qualified water content. The operation process is relatively complicated and the production efficiency is low. Moreover, the battery cell needs to be disassembled to determine the water content, which is easy to cause damage to the battery cell, thereby increasing the manufacturing cost.

[0024] In order to solve the above problems, the present application provides a method, device, electronic device, readable storage medium, and program product for determining the water content of a battery cell; further, through the correlation (negative correlation) between the water content of the battery cell and the insulation resistance of the battery cell, the water content (qualified or unqualified) of the battery cell is determined by determining the insulation resistance value of the battery cell. In this way, the insulation resistance value can be directly detected by a detection instrument (such as an insulation resistance tester) without disassembling the battery cell, and without meeting the above-mentioned temperature and humidity requirements and operating requirements that need to be met after disassembly, so the error of the determined water content can be reduced and the accuracy can be improved. In addition, the operation process is simplified, the production efficiency is improved, and the manufacturing cost is reduced.

[0025] It is understandable that the above method for determining the water content of a battery cell can be performed in a detection device, which can include, for example, an insulation resistance tester, a terminal computer, a server, a cloud platform, and the like.

[0026] It should be noted that the defects existing in the solutions in the above-mentioned related technologies are obtained by the inventors after long-term practice and careful research. Therefore, the discovery process of the above-mentioned problems and the solutions proposed in the embodiments of the present invention for the above-mentioned problems below should all be the contributions made by the inventors to the present invention in the process of the present invention.

[0027] See also Figure 1 , which shows a flow chart of a method for determining the water content of a battery cell provided in an embodiment of the present application. Figure 1 As shown, the method for determining the water content of a battery cell includes the following steps 101 to 103.

[0028] Step 101, obtaining the actual measured value of the insulation resistance of the battery cell to be tested; The battery cell to be tested is also the battery cell whose water content is to be determined, which may be, for example, a battery cell of a ternary lithium battery, a lithium iron phosphate battery, or the like.

[0029] The above-mentioned insulation resistance actual measured value is also the insulation resistance value actually measured of the battery cell to be tested, which can be obtained by, for example, measuring with an insulation resistance tester.

[0030] In some application scenarios, if the detection device is an insulation resistance tester, the actual insulation resistance value of the battery cell to be tested is obtained when the insulation resistance value is measured. If the detection device is other equipment, it can be obtained from the insulation resistance tester, and those skilled in the art can obtain it according to actual conditions, and this application is not limited here.

[0031] Step 102, obtaining a measured state value of a cell water resistance influencing factor, wherein the cell water resistance influencing factor is a factor that affects the relationship between the water content and the insulation resistance value of the cell; In some optional implementations, the factors affecting the water resistance of the battery cell include one or more of the following: ambient humidity, measurement voltage, battery cell temperature, and SOC of the battery cell.

[0032] Among them, regarding the ambient humidity, in a high humidity environment, the battery cell is more likely to absorb moisture, resulting in a decrease in insulation resistance; while in a low humidity environment, the water content of the battery cell is lower and the insulation resistance is higher. Therefore, ambient humidity is an important factor affecting the relationship between the water content of the battery cell and the insulation resistance value.

[0033] Regarding the measurement voltage, a higher measurement voltage will increase the electric field strength inside the insulating material, causing more ion migration and polarization, thereby increasing the leakage current and reducing the insulation resistance. Therefore, the measurement voltage is an important factor affecting the relationship between the water content and the insulation resistance value of the battery cell.

[0034] Regarding the cell temperature, an increase in the cell temperature will accelerate the rate of chemical reactions within the cell and reduce the insulation resistance; a decrease in temperature will slow down the rate of chemical reactions within the cell and increase the insulation resistance. In addition, the cell temperature will also affect the cell's ability to absorb water, thereby affecting the water content. Therefore, the cell temperature is an important factor affecting the relationship between the water content and insulation resistance of the cell.

[0035] Regarding the SOC (State Of Charge, SOC for short) of the battery cell, the SOC of the battery cell will affect the activity of the chemical reaction inside it, thereby affecting the insulation resistance. For example, at a high SOC, the ion migration rate inside the battery cell is faster, which may lead to a decrease in insulation resistance. Therefore, the SOC of the battery cell is an important factor affecting the relationship between the water content of the battery cell and the insulation resistance value.

[0036] It should be noted that, in addition to the multiple factors listed above, the factors affecting the water resistance of the battery cell may also include, for example, the material properties of the battery cell, the degree of aging, the electrolyte composition, the electrolyte concentration, etc. Those skilled in the art may adaptively obtain the measured state values ​​of one or more of these factors according to actual needs.

[0037] The measured state value of the above-mentioned cell water resistance influencing factor can be regarded as the specific value of the cell water resistance influencing factor in the actual measurement process. For example, when the cell water resistance influencing factor is the cell temperature, its corresponding measured state value can be 40°C. When the cell water resistance influencing factor is the cell SOC, its corresponding measured state value can be 25%.

[0038] In some application scenarios, the detection device can directly obtain the measured state value of the factors affecting the water resistance of the battery cell from various measuring devices. For example, the measured state value of the battery cell temperature is obtained from a temperature sensor used to detect the temperature of the battery cell. The ambient humidity is obtained from a temperature and humidity monitor placed in the detection space.

[0039] In other application scenarios, the detection equipment can also indirectly obtain the measured state value of the factors affecting the water resistance of the battery cell. For example, the OCV (open circuit voltage) of the battery cell is obtained from the OCV test equipment, and then the SOC of the battery cell is obtained through the corresponding relationship between OCV and SOC.

[0040] Step 103: Determine the water content of the battery cell to be tested according to the actually measured value of the insulation resistance and the actually measured state value of the factor affecting the water resistance of the battery cell.

[0041] In other words, the testing equipment can determine whether the water content of the battery cell to be tested is qualified by combining the actual measured value of the insulation resistance and the actual measured state value of the factors affecting the water resistance of the battery cell.

[0042] It is understandable that when determining the water content of the battery cell to be tested, one or more water resistance influencing factors of the battery cell can be considered. Then, in some application scenarios, if only one water resistance influencing factor of the battery cell is considered, the water content of the battery cell to be tested can be determined only in combination with the measured state value of the water resistance influencing factor of the battery cell and the measured value of the insulation resistance. For example, a correspondence between the insulation resistance value, the water content of the battery cell, and the measured state value of only one water resistance influencing factor of the battery cell can be established, and then determined based on the corresponding relationship. For example, for a sample battery cell, if it is measured that when the battery cell temperature is T1, the insulation resistance value is R1 and the water content of the battery cell is M1, the three data can be associated to obtain the associated corresponding relationship. Then, after obtaining the measured value of the insulation resistance and the battery cell temperature of the battery cell to be tested, it can be found in the established corresponding relationship whether there is a corresponding water content. If so, the found water content can be determined as the water content of the battery cell to be tested. If it does not exist, the insulation resistance value of the nearest neighbor of the actual measured insulation resistance value and / or the state value of the nearest neighbor of the battery cell temperature can be found, and then the corresponding water content can be found from the corresponding relationship, and the found water content can be determined as the water content of the battery cell to be tested, so that whether the battery cell to be tested is qualified can be determined based on the water content.

[0043] Alternatively, the moisture content of the battery cell to be tested can also be determined with the help of machine learning. For example, the insulation resistance values, corresponding battery cell temperatures, and moisture content qualifications of multiple sample battery cells can be pre-calibrated; then the model is trained with the calibrated data to obtain a converged model, so that the actual insulation resistance values ​​of the battery cell to be tested and the battery cell temperature can be input into the model to obtain the moisture content of the battery cell to be tested. The model here can include, for example, a neural network model, a random forest model, a support vector machine model, and the like. Here, for example, the calibrated insulation resistance values ​​and battery cell temperatures of the sample battery cells can be used as model inputs, and the calibrated moisture content qualifications can be used as the expected input training model.

[0044] In other application scenarios, if multiple factors affecting the water resistance of battery cells are considered, the water content of the battery cell to be tested can be determined by combining the measured state values ​​of these multiple factors affecting the water resistance of battery cells and the measured value of insulation resistance. Similarly, the detection equipment can also establish a correspondence between the insulation resistance value, the water content of the battery cell and these multiple measured state values, and then make a determination based on the correspondence. For example, for a sample battery cell, if it is measured that when the battery cell temperature is T2, the measured voltage is U2, and the battery cell SOC is 25%, the insulation resistance value is R2, and the water content of the battery cell is M2, then these five can be associated to obtain the associated correspondence. Then, after obtaining the measured value of the insulation resistance, battery cell temperature, measured voltage, and battery cell SOC of the battery cell to be tested, it is possible to find out whether there is a corresponding water content in the established correspondence. If so, the found water content can be determined as the water content of the battery cell to be tested. If it does not exist, the insulation resistance value of the nearest neighbor of the actual measured insulation resistance value and / or the state value of the nearest neighbor of the actual measured state value (battery cell temperature, measured voltage and / or battery cell SOC) can be found, and then the corresponding water content can be found from the corresponding relationship, and the found water content can be determined as the water content of the battery cell to be tested, so that whether the battery cell to be tested is qualified can be determined based on the water content.

[0045] Alternatively, the water content of the battery cell to be tested can also be determined with the help of machine learning. Specifically, the insulation resistance values ​​of multiple sample battery cells, the corresponding measured state values ​​of various battery cell water resistance influencing factors, and the qualified water content can be pre-calibrated; then the model is trained with the calibrated data to obtain a converged model, so that the measured insulation resistance values ​​of the battery cell to be tested and the measured state values ​​of various battery cell water resistance influencing factors can be input into the model to obtain the water content of the battery cell to be tested. Here, for example, the calibrated insulation resistance value of the sample battery cell and its corresponding measured state values ​​of various battery cell water resistance influencing factors (i.e., battery cell temperature, measurement voltage, battery cell SOC) can be used as model input, and the calibrated qualified water content can be used as the expected input to train the model.

[0046] In this implementation, the water content of the battery cell can be determined by determining the insulation resistance value of the battery cell to be tested through the correlation between the water content and the insulation resistance. In this way, there is no need to disassemble the battery cell, nor to meet the stringent requirements that need to be met after disassembly, so the error of the determined water content can be reduced and the accuracy can be improved. In addition, the operation process is simplified, the production efficiency is improved, and the manufacturing cost is reduced.

[0047] In addition, the influence of the water resistance influencing factor of the battery cell on the relationship between the water content and the insulation resistance value of the battery cell is further taken into consideration. Therefore, the water content of the battery cell to be tested is determined by combining the actual measured value of the insulation resistance and the measured state value of the water resistance influencing factor of the battery cell, which can further reduce the error of the water content and improve the accuracy.

[0048] In some optional implementations, the step 103 described above of determining the water content of the battery cell to be tested according to the measured value of the insulation resistance and the measured state value of the factor affecting the water resistance of the battery cell comprises the following sub-steps: Sub-step 1031, determining a target insulation resistance reference threshold value of the cell water resistance influencing factor at the measured state value according to the calibrated insulation resistance reference threshold values ​​of the cell water resistance influencing factor at different state values; The above insulation resistance reference threshold can be regarded as the insulation resistance value corresponding to the qualified water content threshold of the battery cell, which can be obtained through a sample battery cell with qualified water content. Among them, if the water content is greater than the qualified water content threshold, it can be regarded as the water content of the battery cell is unqualified; if the water content is not greater than the qualified water content threshold, it can be regarded as the water content of the battery cell is qualified. Then, if the insulation resistance value is greater than the insulation resistance reference threshold, it can be regarded as the water content of the battery cell is qualified; if the insulation resistance value is not greater than the insulation resistance reference threshold, it can be regarded as the water content of the battery cell is unqualified.

[0049] It is understandable that when the water resistance influencing factor of the battery cell is at different state values, the corresponding insulation resistance reference threshold value may be the same or different. The detection equipment can calibrate the insulation resistance reference threshold values ​​corresponding to different state values, so that when the measured state value corresponding to the battery cell to be tested is obtained, the above-mentioned target insulation resistance reference threshold value can be obtained based on the pre-calibrated data.

[0050] For example, the detection equipment can pre-calibrate multiple insulation resistance reference thresholds of sample cells with qualified moisture content at different cell temperatures, so that the insulation resistance reference threshold of the cell to be tested at the measured temperature value can be determined based on the measured temperature value of the cell to be tested and the calibrated multiple insulation resistance reference thresholds, and the insulation resistance reference threshold can be determined as the target insulation resistance reference threshold.

[0051] Sub-step 1032, determining the water content of the battery cell to be tested according to the actual insulation resistance value and the target insulation resistance reference threshold.

[0052] In some application scenarios, for example, the actual measured insulation resistance value can be compared with the target insulation resistance reference threshold. If the actual measured insulation resistance value is not less than the target insulation resistance reference threshold, it can be determined that the moisture content of the battery cell to be tested is qualified; otherwise, it is determined that the moisture content of the battery cell to be tested is unqualified.

[0053] In this implementation, a more accurate target insulation resistance reference threshold can be obtained based on a pre-calibrated insulation resistance reference threshold, so that when the moisture content of the battery cell to be tested is determined based on the target insulation resistance reference threshold, the accuracy of the determination result can be improved.

[0054] Furthermore, the present application provides the following multiple implementation methods for determining a target insulation resistance reference threshold.

[0055] Implementation method 1: According to the insulation resistance reference threshold value of the calibrated battery cell water resistance influencing factor at different state values, the target insulation resistance reference threshold value is determined using a preset interpolation algorithm.

[0056] The above-mentioned preset interpolation algorithm may include, for example, linear interpolation, polynomial interpolation, etc.

[0057] It is understandable that factors such as calibration efficiency and calibration cost are involved in the actual calibration process, so the insulation resistance reference threshold corresponding to each state value may not be calibrated in advance. Therefore, even if multiple insulation resistance reference thresholds are calibrated, there is a situation where the target insulation resistance reference threshold cannot be directly found among these multiple insulation resistance reference thresholds. In this case, a preset interpolation algorithm can be used to determine the insulation resistance reference threshold at the actual measured state value, so that the insulation resistance reference threshold can be determined as the target insulation resistance reference threshold.

[0058] For example, the insulation resistance reference threshold R1' at 20°C and the insulation resistance reference threshold R3' at 30°C are pre-calibrated, but the insulation resistance reference threshold R2' at 25°C is not calibrated. The actual temperature value of the battery cell to be tested is 25°C. The insulation resistance reference threshold R1' at 20°C and the insulation resistance reference threshold R3' at 30°C can be used to obtain the insulation resistance reference threshold R2' at 25°C based on the preset interpolation algorithm. Therefore, R2' can be determined as the target insulation resistance reference threshold.

[0059] In this implementation, a preset interpolation algorithm can be used to determine the target insulation resistance reference threshold, which reduces the calibration workload to a certain extent and improves the determination efficiency and accuracy of the target insulation resistance reference threshold.

[0060] Implementation method two, according to the calibrated insulation resistance reference threshold value of the battery cell water resistance influencing factor at different state values, obtain the fitting relationship between the state value and the insulation resistance reference threshold value; based on the fitting relationship, determine the target insulation resistance reference threshold value at the measured state value.

[0061] In some application scenarios, for example, the least square method or spline function can be used for fitting to obtain a fitting relationship between the state value and the insulation resistance reference threshold, so that the corresponding target insulation resistance reference threshold can be obtained based on the fitting relationship and the measured state value.

[0062] In this implementation, the target insulation resistance reference threshold is determined through the fitting relationship, which reduces the calibration workload to a certain extent and improves the determination efficiency and the accuracy of the target insulation resistance reference threshold.

[0063] Implementation method three, inputting the measured state value into a prediction model to obtain the target insulation resistance reference threshold; the prediction model is trained based on the insulation resistance reference threshold at different state values ​​and the cell water resistance influencing factors at different state values.

[0064] The above prediction model may also include, for example, a neural network model, a random forest model, a support vector machine model, etc.

[0065] It is understandable that the prediction model can be obtained by training the initial prediction model. When training the initial prediction model, the calibrated different state values ​​(battery cell temperature and / or battery cell SOC and / or measured voltage and / or ambient humidity) can be input into the initial prediction model, and then the insulation resistance reference threshold at different state values ​​can be used as the expected output to train the initial prediction model, thereby obtaining the above prediction model. For example, the calibrated battery cell temperature and / or battery cell SOC and / or measured voltage and / or ambient humidity can be used as the input of the initial prediction model, and the calibrated corresponding insulation resistance reference threshold can be used as the expected output to train the initial prediction model to obtain the prediction model.

[0066] In this implementation, the target insulation resistance reference threshold can be obtained with the help of a prediction model, which is trained based on the insulation resistance reference thresholds of different pre-calibrated state values ​​and cell water resistance influencing factors at different state values. Therefore, when facing the measured state value, a more accurate target insulation resistance reference threshold can be obtained.

[0067] In some optional implementations, the step 1032 described above of determining the water content of the battery cell to be tested according to the actual insulation resistance value and the target insulation resistance reference threshold value includes: First, determining a first resistance change between an insulation resistance measured value corresponding to a first measured state value and an insulation resistance measured value corresponding to a second measured state value; In some application scenarios, for example, the insulation resistance measured value corresponding to the first measured state value and the insulation resistance measured value corresponding to the second measured state value may be subtracted or divided to obtain a resistance difference, which is also the first resistance change.

[0068] Among them, the first measured state value and the second measured state value can be different values ​​under the same battery cell water resistance influencing factor, or can be different values ​​under different battery cell water resistance influencing factors, which is not limited here.

[0069] Then, determining a second resistance change between a target insulation resistance reference threshold corresponding to the first measured state value and a target insulation resistance reference threshold corresponding to the second measured state value; Similarly, for example, the target insulation resistance reference threshold corresponding to the first measured state value and the target insulation resistance reference threshold corresponding to the second measured state value may be subtracted or divided to obtain a resistance difference, which is also the second resistance change.

[0070] Finally, the water content of the battery cell to be tested is determined according to the first resistance change and the second resistance change.

[0071] It can be understood that the insulation resistance reference threshold corresponds to the qualified water content threshold. Therefore, when changing from the same first measured state value to the same second measured state value, if the resistance change of the insulation resistance of the battery cell to be tested (i.e., the first resistance change) is the same as the resistance change between the corresponding insulation resistance reference threshold (i.e., the second resistance change) or is within the preset error range, it can be proved that the battery cell to be tested has the same insulation resistance change as the sample battery cell with qualified water content, so it can be determined that the battery cell to be tested has the same water content change as the sample battery cell with qualified water content, so it can be determined that the water content of the battery cell to be tested is qualified. Otherwise, it can be determined that the water content of the battery cell to be tested is unqualified.

[0072] In this implementation, it is considered that the insulation resistance value will change after the state value changes. Therefore, the water content of the battery cell to be tested can be determined more accurately through the insulation resistance value change caused by the measured state value with the same change.

[0073] In some optional implementations, after determining the water content of the battery cell to be tested according to the measured value of the insulation resistance and the measured state value of the water resistance influencing factor of the battery cell in the above step 103, the method further includes: Step 1, obtaining a plurality of insulation resistance reference values ​​corresponding to the measured state values ​​of the calibrated battery cell at different water contents; For example, when the water content of the calibrated battery cell is N1, the corresponding insulation resistance reference value when the measured temperature value is T is r1; when the water content is N2, the corresponding insulation resistance reference value when the measured temperature value is T is r2. When the water content is N3, the corresponding insulation resistance reference value when the measured temperature value is T is r3.

[0074] Step 2, comparing the multiple insulation resistance reference values ​​with the insulation resistance measured value respectively, and determining the insulation resistance reference value with the smallest resistance difference; For example, the above r1, r2, r3 are respectively subtracted from the actual insulation resistance value, thereby obtaining the difference between r1, r2, r3 and the actual insulation resistance value. Then, the various differences can be compared to obtain the minimum difference, thereby determining the insulation resistance reference value corresponding to the minimum difference.

[0075] Step 3: determine the water content of the battery cell to be tested according to the water content corresponding to the insulation resistance reference value with the smallest resistance difference.

[0076] For example, if the insulation resistance reference value with the smallest resistance difference is r1, the corresponding water content N1 can be determined as the water content of the battery cell to be tested. Alternatively, N1 can be corrected according to the degree of resistance difference to determine the water content of the battery cell to be tested. In addition, if there are multiple insulation resistance reference values ​​with the smallest resistance difference (such as r1 and r2), the average of the water contents corresponding to these multiple insulation resistance reference values ​​can be taken as the water content of the battery cell to be tested (such as the average of N1 and N2).

[0077] In this implementation, the specific water content of the battery cell to be tested can be obtained, so as to facilitate the subsequent determination of a baking strategy based on the specific water content, so as to improve the baking efficiency and obtain a battery cell with a qualified water content. The baking strategy here may include, for example, what baking time and what baking temperature to use for baking.

[0078] Furthermore, the present application illustrates the implementation process and technical effects of the above steps through the following test process: First, multiple sample cells of the same type can be obtained, and the insulation resistance value and water content of each sample cell can be determined respectively, and the relationship between the insulation resistance value and the water content can be established, and the following can be obtained: Figure 2 The insulation resistance value-water content relationship diagram shown in FIG. 1 shows that the insulation resistance value of the battery cell is negatively correlated with its water content. Therefore, the negative correlation between the two can be used to determine the water content of the battery cell by using the insulation resistance value detected.

[0079] In some application scenarios, the insulation resistance reference threshold corresponding to the test cell can be obtained. Here, it can be understood that due to the different types of sample cells, the corresponding relationship diagrams may be different. Therefore, when obtaining the insulation resistance reference threshold corresponding to the test cell, the type of the test cell can be determined first, and then the relationship diagram corresponding to the sample cell of the same type can be obtained based on the type. For example, if the test cell is a cell of a lithium iron phosphate battery, the relationship diagram obtained from the sample cell of the lithium iron phosphate battery can be obtained. Then, the insulation resistance reference threshold corresponding to the test cell can be found from the relationship diagram.

[0080] Specifically, you can first determine the water content requirement of the test cell. For example, the water content requirement for a ternary lithium battery is (200-300) ppm, and the water content requirement for a lithium iron phosphate battery is (300-400) ppm. If the test cell is a lithium iron phosphate battery, you can determine that 400 ppm is the qualified water content threshold, and then Figure 2 The insulation resistance value corresponding to 400ppm is found in the relationship diagram shown, and the insulation resistance value of 3600MΩ found is determined as the insulation resistance reference threshold value corresponding to the test cell.

[0081] Based on this, after obtaining 200 test cells of lithium iron phosphate type (including 3 cells with unqualified water content), the insulation resistance value of each test cell can be detected and compared with the insulation resistance reference threshold of 3600MΩ to obtain the following: Figure 3 It can be seen that the present application can determine the water content of each test cell and screen out 3 unqualified cells, thereby improving the accuracy of the determined water content and reducing the risk of over-killing and under-killing.

[0082] Furthermore, considering the influence of the water resistance of the battery cell on the relationship between the water content and the insulation resistance value of the battery cell, the battery cell temperature was further tested as an example. First, the insulation resistance reference threshold at different battery cell temperatures was calibrated. Here, during calibration, a sample battery cell with qualified water content after baking can be obtained, and the sample battery cell is left to stand for a period of time (not less than 2 hours) at different temperatures, and then its insulation resistance value is measured. In this way, the relationship between the battery cell temperature and the insulation resistance value corresponding to the sample battery cell with qualified water content can be established, and the result is as follows: Figure 4The cell temperature-insulation resistance value relationship diagram is shown. Then, the sample cell can be disassembled to measure its actual water content at different cell temperatures. Then, the relationship between cell temperature-insulation resistance value-actual water content can be established. At this time, based on the qualified water content threshold at room temperature and the actual water content at different cell temperatures, the qualified water content threshold at different cell temperatures can be determined, and then the insulation resistance reference threshold corresponding to the qualified water content threshold at different cell temperatures can be obtained. For example, the qualified water content threshold at room temperature is 400ppm, and the actual water content when the cell temperature is room temperature is A, then the water content difference between the two is (400-A) ppm. For the actual water content at other cell temperatures, the corresponding actual water content can be increased by the difference to obtain the corresponding qualified water content threshold. Then, based on Figure 2 The insulation resistance value-water content relationship diagram shown in the figure is used to determine the insulation resistance values ​​corresponding to each water content qualified threshold. Thus, the insulation resistance reference thresholds at different battery core temperatures are obtained.

[0083] It is understandable that in addition to obtaining the insulation resistance reference threshold at different battery cell temperatures through water content, it can also be obtained through battery cell temperature. Specifically, the insulation resistance reference threshold at different battery cell temperatures can be determined based on the insulation resistance reference threshold at room temperature and the actual insulation resistance value when the battery cell temperature is room temperature. For example, the insulation resistance reference threshold at room temperature is 3600MΩ, and the actual insulation resistance value when the battery cell temperature is room temperature is r', then the insulation resistance difference between the two is (3600-r')MΩ, for the actual insulation resistance values ​​at other battery cell temperatures, the corresponding actual insulation resistance values ​​can be increased by the difference to obtain the corresponding insulation resistance reference threshold. At this point, the insulation resistance reference threshold at different battery cell temperatures has been calibrated.

[0084] Then, after obtaining the measured state value of the test cell, the corresponding target insulation resistance reference threshold value may be determined, so as to determine the water content of the test cell through the measured state value and the target insulation resistance reference threshold value.

[0085] Furthermore, the present application obtained 100 test cells of lithium iron phosphate type (including 3 cells with unqualified water content), and then determined the insulation resistance value of each test cell after being placed for different time periods, and then compared the insulation resistance value with the target insulation resistance reference threshold value to obtain the following: Figure 5 It can be seen that the present application can determine the water content of each test cell and screen out 3 unqualified cells, thereby improving the accuracy of the determined water content and reducing the risk of over-killing and under-killing.

[0086] Those skilled in the art will appreciate that, in the above method of a specific embodiment, the order in which the steps are written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of the steps should be determined by their functions and possible internal logic.

[0087] See also Figure 6 , which shows a structural block diagram of a battery cell water content determination device provided in an embodiment of the present application. The battery cell water content determination device may be a module, program segment or code on an electronic device. It should be understood that the device is similar to the above Figure 1 The method embodiment corresponds to and can be executed Figure 1 The method embodiment involves various steps.

[0088] Optionally, the above-mentioned battery cell water content determination device includes a first acquisition module 601, a second acquisition module 602 and a determination module 603. Among them, the first acquisition module 601 is used to obtain the actual insulation resistance value of the battery cell to be tested; the second acquisition module 602 is used to obtain the actual state value of the battery cell water resistance influencing factor, the battery cell water resistance influencing factor is a factor that affects the relationship between the water content and the insulation resistance value of the battery cell; the battery cell water resistance influencing factor includes one or more of the following: ambient humidity, measurement voltage, battery cell temperature, battery cell SOC; the determination module 603 is used to determine the water content of the battery cell to be tested according to the actual insulation resistance value and the actual state value of the battery cell water resistance influencing factor.

[0089] Optionally, the determination module 603 is further used to: determine the target insulation resistance reference threshold value of the battery cell water resistance influencing factor at the measured state value according to the insulation resistance reference threshold value of the calibrated battery cell water resistance influencing factor at different state values; determine the water content of the battery cell to be tested according to the measured insulation resistance value and the target insulation resistance reference threshold value.

[0090] Optionally, the determination module 603 is further used to: determine the target insulation resistance reference threshold value according to the insulation resistance reference threshold value of the calibrated cell water resistance influencing factor at different state values ​​and by using a preset interpolation algorithm.

[0091] Optionally, the determination module 603 is further used to: obtain a fitting relationship between the state value and the insulation resistance reference threshold value according to the insulation resistance reference threshold value of the calibrated battery cell water resistance influencing factor at different state values; and determine the target insulation resistance reference threshold value at the measured state value based on the fitting relationship.

[0092] Optionally, the determination module 603 is further used to: input the measured state value into a prediction model to obtain the target insulation resistance reference threshold; the prediction model is trained based on the insulation resistance reference threshold at different state values ​​and the cell water resistance influencing factors at different state values.

[0093] Optionally, the determination module 603 is further used to: determine a first resistance change between an insulation resistance measured value corresponding to a first measured state value and an insulation resistance measured value corresponding to a second measured state value; determine a second resistance change between a target insulation resistance reference threshold corresponding to the first measured state value and a target insulation resistance reference threshold corresponding to the second measured state value; and determine the moisture content of the battery cell to be tested based on the first resistance change and the second resistance change.

[0094] Optionally, the device also includes a water content determination module, which is used to: after determining the water content of the battery cell to be tested based on the actual measured value of the insulation resistance and the measured state value of the water resistance influencing factor of the battery cell, obtain a plurality of insulation resistance reference values ​​corresponding to the calibrated battery cell at different water contents and at the measured state value; compare the multiple insulation resistance reference values ​​with the actual measured value of the insulation resistance respectively to determine the insulation resistance reference value with the smallest resistance difference; determine the water content of the battery cell to be tested based on the water content corresponding to the insulation resistance reference value with the smallest resistance difference.

[0095] It should be noted that those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system or device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0096] See also Figure 7 , Figure 7 A schematic diagram of the structure of an electronic device for executing a method for determining the water content of a battery cell provided in an embodiment of the present application, the electronic device may include: at least one processor 701, such as a CPU, at least one communication interface 702, at least one memory 703 and at least one communication bus 704. Among them, the communication bus 704 is used to realize direct connection and communication between these components. Among them, the communication interface 702 of the device in the embodiment of the present application is used to communicate signaling or data with other node devices. The memory 703 can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The memory 703 can optionally be at least one storage device located away from the aforementioned processor. Computer-readable instructions are stored in the memory 703. When the computer-readable instructions are executed by the processor 701, the electronic device can execute the methods provided by the above-mentioned method embodiments.

[0097] Understandably, Figure 7 The structure shown is for illustration only, and the electronic device may also include Figure 7 More or fewer components as shown, or with Figure 7 Different configurations shown. Figure 7 Each component shown in the figure can be implemented by hardware, software or a combination thereof.

[0098] An embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the methods provided by the above-mentioned method embodiments can be executed.

[0099] An embodiment of the present application provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium, and the computer program includes program instructions. When the program instructions are executed by a computer, the computer can execute the methods provided by the above-mentioned method embodiments.

[0100] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0101] In addition, 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, that is, they 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.

[0102] Furthermore, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0103] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0104] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for determining the water content of a battery cell, characterized in that: include: Obtain the actual measured value of the insulation resistance of the battery cell to be tested; Obtaining the measured state value of the cell water resistance influencing factor, wherein the cell water resistance influencing factor is a factor that affects the relationship between the water content and the insulation resistance value of the cell; the cell water resistance influencing factor includes one or more of the following: ambient humidity, measurement voltage, cell temperature, and cell SOC; The water content of the battery cell to be tested is determined according to the measured value of the insulation resistance and the measured state value of the factor affecting the water resistance of the battery cell.

2. The method according to claim 1, characterized in that The determining the water content of the battery cell to be tested according to the measured value of the insulation resistance and the measured state value of the factor affecting the water resistance of the battery cell comprises: Determine a target insulation resistance reference threshold value of the cell water resistance influencing factor at the measured state value according to the calibrated insulation resistance reference threshold value of the cell water resistance influencing factor at different state values; The water content of the battery cell to be tested is determined according to the actual insulation resistance value and the target insulation resistance reference threshold.

3. The method according to claim 2, characterized in that The step of determining the target insulation resistance reference threshold value of the cell water resistance influencing factor at the measured state value according to the calibrated insulation resistance reference threshold value of the cell water resistance influencing factor at different state values ​​includes: According to the insulation resistance reference thresholds of the calibrated battery cell water resistance influencing factors at different state values, the target insulation resistance reference threshold is determined using a preset interpolation algorithm.

4. The method according to claim 2, characterized in that: The step of determining the target insulation resistance reference threshold value of the cell water resistance influencing factor at the measured state value according to the calibrated insulation resistance reference threshold value of the cell water resistance influencing factor at different state values ​​includes: According to the insulation resistance reference threshold values ​​of the calibrated battery cell water resistance influencing factors at different state values, a fitting relationship between the state value and the insulation resistance reference threshold value is obtained; Based on the fitting relationship, a target insulation resistance reference threshold value at the actual measured state value is determined.

5. The method according to claim 2, characterized in that: The step of determining the target insulation resistance reference threshold value of the cell water resistance influencing factor at the measured state value according to the calibrated insulation resistance reference threshold value of the cell water resistance influencing factor at different state values ​​includes: The measured state value is input into a prediction model to obtain the target insulation resistance reference threshold value; the prediction model is trained based on the insulation resistance reference threshold values ​​of the different state values ​​and the cell water resistance influencing factors at different state values.

6. The method according to any one of claims 2 to 5, characterized in that: The step of determining the water content of the battery cell to be tested according to the insulation resistance measured value and the target insulation resistance reference threshold value includes: Determine a first resistance change between an insulation resistance measured value corresponding to the first measured state value and an insulation resistance measured value corresponding to the second measured state value; Determine a second resistance change between a target insulation resistance reference threshold corresponding to the first measured state value and a target insulation resistance reference threshold corresponding to the second measured state value; The water content of the battery cell to be tested is determined according to the first resistance change and the second resistance change.

7. The method according to any one of claims 1 to 5, characterized in that: After determining the water content of the battery cell to be tested according to the measured value of the insulation resistance and the measured state value of the water resistance influencing factor of the battery cell, the method further includes: Obtaining multiple insulation resistance reference values ​​corresponding to the measured state values ​​of the calibrated battery cell at different water contents; Compare the multiple insulation resistance reference values ​​with the insulation resistance measured value respectively, and determine the insulation resistance reference value with the smallest resistance difference; The water content of the battery cell to be tested is determined according to the water content corresponding to the insulation resistance reference value with the smallest resistance difference.

8. A device for determining water content of a battery cell, characterized in that: include: The first acquisition module is used to obtain the actual measured value of the insulation resistance of the battery cell to be tested; The second acquisition module is used to obtain the measured state value of the cell water resistance influencing factor, wherein the cell water resistance influencing factor is a factor that affects the relationship between the water content and the insulation resistance value of the cell; the cell water resistance influencing factor includes one or more of the following: ambient humidity, measurement voltage, cell temperature, and cell SOC; The determination module is used to determine the water content of the battery cell to be tested according to the actual measured value of the insulation resistance and the actual measured state value of the water resistance influencing factor of the battery cell.

9. An electronic device, characterized in that: The method comprises a processor and a memory, wherein the memory stores computer-readable instructions. When the computer-readable instructions are executed by the processor, the method according to any one of claims 1 to 7 is executed.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is performed.

11. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, the method according to any one of claims 1 to 7 is performed.

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