Soft package battery seal edge false seal detection and analysis method

Abstract

The invention belongs to the technical field of battery detection, and discloses a soft package battery seal edge false seal detection analysis method, which comprises the following steps: calculating a pressure parameter, a water injection rate parameter and pressure holding time based on a fixed pressure parameter and fixed pressure holding time; based on the water injection quantity parameter, adding liquid into the packaged battery cell, and carrying out secondary edge sealing on one side of a battery cell air bag of the packaged battery cell added with the liquid; based on the pressure parameter and the dwell time, performing a water pressure test on the packaged battery cell by using a water pressure test machine; and if a water pressure test result shows that a liquid leakage phenomenon exists, dissolving the aluminum film of the packaged battery cell by using a sodium carbonate solution, and judging an abnormal point location based on the reserved PP layer. According to the invention, the detection effect and the rapid identification capability of the false sealing phenomenon of the seal edge of the soft package battery can be improved.

Description

Technical Field

[0001] The present application relates to the field of battery detection technology, and in particular to a method for detecting and analyzing false seals on the seal edges of soft-pack batteries. Background Art

[0002] In the soft-pack battery industry, the aluminum-plastic film must be punched before the bare battery cell is packaged. After the aluminum-plastic film is punched into the required specifications, the battery cell is packaged. The quality of the package directly determines the performance of the battery. If there is a false seal, the battery is prone to corrosion and leakage. The current industry detection methods for false seals and poor seals are mainly a. Multi-point detection of edge thickness. The disadvantage of this method is that the detection area is fixed. If there is a small area of ​​false seal in the undetected area, it cannot be effectively identified. After long-term corrosion by the electrolyte, the aluminum film is damaged, causing leakage, flatulence, etc.; b. Tensile test. The tensile strength of the seal is tested by a tensile testing machine to reflect whether the seal strength of the finished product made by the current head meets the specified standards. The tensile testing machine for the heat seal strength of the aluminum-plastic film seal of the soft-pack battery mainly works on the principle of tensile mechanics. During the test, the aluminum-plastic film seal sample is fixed between two clamps, and the aluminum-plastic film sample is stretched by applying external force. The test machine records the elongation of the sample and the force applied to the seal. By measuring the maximum tensile force of the seal, heat seal strength and other parameters, the aluminum-plastic film seal strength is evaluated. This method has many factors that affect the final test results, such as: the presence of machine vibration, temperature, humidity and other influences in the test environment; secondly, factors such as the size of the test sample and the sample fixing method in the operator's operation can affect the final test results and cause data distortion.

[0003] Therefore, how to improve the detection effect of false sealing of soft-pack battery sealing edges and the ability to quickly identify whether the sealing edge strength of the aluminum-plastic film of the soft-pack battery cell meets the standards is extremely urgent and pressing. Summary of the invention

[0004] The present invention provides a method for detecting and analyzing false sealing of a seal edge of a soft-pack battery, aiming to solve the technical problems of how to improve the detection effect of the false sealing phenomenon of the seal edge of a soft-pack battery and the ability to quickly identify whether the strength of the aluminum-plastic edge sealing of a soft-pack battery core meets the standard.

[0005] In order to achieve the above-mentioned invention object, the first aspect of the present invention provides a method for detecting and analyzing false seals on the seal edge of a soft-pack battery, comprising:

[0006] Based on fixed pressure parameters and fixed pressure holding time, the water pressure test results under different water injection volumes are verified to obtain the water injection volume range. Based on the water injection volume range verification, the pressure parameter range is further verified. The pressure holding time can be further verified through the verified pressure parameter range and water injection volume range.

[0007] Based on the water injection amount parameter, liquid is added into the packaged battery cell, and a second edge is sealed on one side of the battery cell air bag of the packaged battery cell to which the liquid is added;

[0008] Based on the pressure parameter and the pressure holding time, using a water pressure testing machine to perform a water pressure test on the packaged battery cell;

[0009] If the water pressure test results show leakage, use sodium carbonate solution to dissolve the aluminum film of the packaged battery cell and determine the abnormal point based on the retained PP layer.

[0010] Furthermore, the step of calculating the pressure parameter, the water injection volume parameter and the pressure holding time comprises:

[0011] Based on the preset fixed pressure parameters and fixed pressure holding time, verify the water pressure test results under different water injection volumes and obtain the water injection volume coefficient;

[0012] Verify the range of pressure parameters by the water injection coefficient;

[0013] Verifying the pressure holding time range based on the pressure parameter range and the water injection coefficient;

[0014] Based on the range of the pressure parameters, the water injection coefficient and the pressure holding time range, the pressure parameters, water injection parameters and pressure holding time applicable to the battery cell test water pressure are determined.

[0015] Furthermore, sodium carbonate is dissolved in a water solvent at 30° C. to 40° C. at a concentration of 0.94-0.1.44 mol / L to obtain the sodium carbonate solution.

[0016] Furthermore, if the water pressure test result shows leakage, the step of using a sodium carbonate solution to dissolve the aluminum film of the packaged battery cell and determining the abnormal point based on the retained PP layer includes:

[0017] If the water pressure test result shows leakage, the aluminum film is placed in a container containing the sodium carbonate solution for soaking, and the residual alkali solution on the surface of the packaged battery cell is rinsed after the aluminum film is completely dissolved;

[0018] Under natural light conditions, use direct observation or two-dimensional analysis to determine abnormal points on the retained PP layer.

[0019] Furthermore, the step of performing a water pressure test on the packaged battery cells using a water pressure tester includes: folding the battery cell air bag in half at a position equal to half of the effective air bag width, and pressing the folded position tightly and placing it under a pressure plate of the water pressure tester.

[0020] Furthermore, the water injection volume parameter is 1.1-1.5 times the water injection volume coefficient*battery cell liquid injection volume.

[0021] Furthermore, the second edge sealing includes using a packaging machine to perform a second sealing on one side of the battery cell air bag of the packaged battery cell; wherein the sealing position is 5-15 mm away from the upper edge of the air bag.

[0022] Furthermore, the packaged battery cells include degraded bare batteries or short-circuited bare batteries during the period.

[0023] Furthermore, the pressure parameter is 60-70Kg / cm2.

[0024] Furthermore, the holding time is 1-5 minutes.

[0025] Beneficial effects:

[0026] This application simulates the pressure under actual use conditions through water pressure testing, and can intuitively detect whether there is a false seal phenomenon in the battery cell, that is, whether there is abnormal leakage. This detection method is more intuitive than the traditional multi-point detection of edge sealing thickness or tensile test, and can identify abnormal points more quickly. In the event of leakage, sodium carbonate solution is used to dissolve the aluminum layer and nylon layer in the aluminum-plastic film. Sodium carbonate is inexpensive and can reduce the cost of the entire detection process; only the PP layer is retained for observation, and the specific position of the edge sealing abnormality can be quickly located, thereby speeding up the detection speed of abnormality detection, and is crucial for subsequent production line adjustments and improvements. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of a flow chart of a method for detecting and analyzing false seals on the seal edge of a soft-pack battery according to an embodiment of the invention;

[0028] Figure 2 A schematic diagram of a sealing edge of a soft-pack battery according to an embodiment of the invention;

[0029] Figure 3 A schematic diagram of the use of a water pressure testing machine according to an embodiment of the invention;

[0030] Figure 4 This is a diagram showing that the PP layer has no abnormality after being soaked in the solution used in one embodiment of the invention;

[0031] Figure 5 This is a diagram showing an abnormal false seal after soaking in a solution according to an embodiment of the invention;

[0032] Figure 6 This is a picture showing that the top seal and side seal edges are normal after the water pressure test of an embodiment of the invention;

[0033] Figure 7 This is a picture of abnormal top seal on the side of the pole ear after the water pressure test of an embodiment of the invention;

[0034] Among them, 1. Top edge sealing; 2. One edge sealing; 3. Second edge sealing; 4. Upper pressure plate; 5. Lower bottom plate;

[0035] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0037] It will be understood by those skilled in the art that, unless expressly stated, the singular forms "a", "an", "above", and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of features, integers, steps, operations, elements, modules, modules and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, modules, modules, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be an intermediate element. In addition, the "connection" or "coupling" used herein may include wireless connection or wireless coupling. The term "and / or" used herein includes all or any module and all combinations of one or more associated listed items.

[0038] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as herein.

[0039] Reference Figure 1-Figure 3 The embodiment of the present invention provides a method for detecting and analyzing false seals on the seal edge of a soft-pack battery, comprising the following steps S1-S4:

[0040] S1. Calculate pressure parameters, water injection volume parameters and holding time based on fixed pressure parameters and fixed holding time;

[0041] S2. Based on the water injection amount parameter, liquid is added into the packaged battery cell, and a second edge is sealed on one side of the battery cell air bag of the packaged battery cell to which the liquid is added;

[0042] S3, based on the pressure parameter and the pressure holding time, using a water pressure testing machine to perform a water pressure test on the packaged battery cell;

[0043] S4. If the water pressure test results show leakage, use sodium carbonate solution to dissolve the aluminum film of the packaged battery cell and determine the abnormal point based on the retained PP layer.

[0044] In step S1, according to the preset fixed pressure parameters (e.g., 60Kg / cm2) and the fixed pressure holding time (e.g., 4 minutes), the water injection amount is changed to verify the results of the water pressure test under different water injection amounts. Through multiple experiments, the optimal water injection amount range that can distinguish normal batteries from abnormal batteries is found, such as a water injection coefficient of 1.1-1.5 times. Within the obtained water injection amount range, the water injection amount is fixed, and the pressure parameter is changed for verification. Through experiments, the optimal pressure parameter range that can distinguish normal batteries from abnormal batteries is determined, such as 60-70Kg / cm2. Based on the obtained water injection amount range and pressure parameter range, these two parameters are fixed, and the pressure holding time is changed for verification. Through experiments, the optimal pressure holding time range that can distinguish normal batteries from abnormal batteries is determined, such as 1-3 minutes. Based on the optimal range obtained in the above steps, the pressure parameters, water injection amount parameters and pressure holding time ultimately used for the water pressure test are determined. The pressure parameter refers to the pressure applied by the water pressure tester, and the water injection parameter = water injection coefficient * battery cell injection volume. Here, since the battery cell injection volume involves confidential parameters, the water injection parameter is disclosed using the water injection coefficient, which is a constant coefficient or multiple used to calculate the water injection parameter. This step can find the best combination of water pressure test parameters to ensure the accuracy and reliability of the test. These parameter combinations can not only effectively identify batteries with false sealing problems, but also help improve detection efficiency and reduce unnecessary waste of resources.

[0045] In step S2, firstly, a packaged cell sample is selected from the production line. The packaged cell is a cell that has been top-sealed 1 (positive electrode sealing and negative electrode sealing) and side-sealed (one edge 2). These samples can be degraded or short-circuited bare cells at the time, or they can be packaged cells on the line. These samples are selected to ensure the timeliness of the test and reduce cost losses. A standard amount of liquid is added to the selected cell, wherein the liquid includes water, such as tap water, etc. The amount of water added is calculated based on the water injection coefficient multiplied by the cell injection volume used in the unit. The water injection coefficient is usually 1.1 to 1.5 times, wherein the cell injection volume is the amount of electrolyte injected into the battery during the manufacturing process. Use an offline packaging machine to perform secondary sealing on one side of the air bag of the cell to form a second edge seal 3. By adding liquid and performing secondary sealing on one side of the air bag, the necessary conditions are created for subsequent water pressure testing. Only when the cell is full of liquid and well sealed can the water pressure test accurately detect whether there is an abnormality in the edge seal. The operation process of this step is simple, does not require complex tools or equipment, reduces the difficulty of operation, improves the implementation efficiency, and ensures the safety of the test process through secondary sealing. It not only provides the necessary conditions for subsequent water pressure testing and abnormal point judgment, but also has the advantages of simple operation, economic efficiency, safety and environmental protection, which helps to improve the efficiency and accuracy of detection and provides strong support for the reliability detection of soft-pack battery edge sealing.

[0046] In step S3, a water pressure testing machine is set according to the determined test parameters. The pressure parameters are adjusted to the specified range, and the pressure holding time is set. For example, the pressure parameters, water injection parameters, and pressure holding time can all be verified experimentally to confirm specific test parameters. For example, the pressure parameter range is 60-70Kg / cm2, the water injection range is 1.1-1.5 times the water injection coefficient, and the pressure holding time range is 1-3 minutes. Then fold the air bag of the battery cell in half at half the effective air bag width, and press the folded position tightly under the pressure plate of the water pressure testing machine. Make sure the battery cells are neatly arranged to ensure the accuracy of the test results. Start the water pressure testing machine and let it test the battery cells according to the set pressure parameters and pressure holding time. Observe the performance of the battery cells under water pressure, especially whether there is leakage at the edge sealing. Determine whether there is any abnormality in the edge sealing based on the test results. If the test results show that there is no leakage, the edge sealing is considered to be good; if there is leakage, it indicates that there is a false seal or other abnormalities. Reference Figure 6-Figure 7 ,in, Figure 6 The middle picture shows that the top seal and side seals are normal after the water pressure test. Figure 7This is a picture of the abnormal top seal on the ear side after the water pressure test. This step can visually detect whether there is a false seal or other abnormalities in the edge sealing of the battery cell through the water pressure test. If the test results show leakage, it means that there is a problem with the edge sealing, and further analysis is required to determine the abnormal point. If there is no leakage, it means that the edge sealing is good and subsequent production and testing can continue. The operating process of this step is simple and clear, without the need for complex tools or equipment, which reduces the difficulty of operation and improves the implementation efficiency. It not only provides an effective detection method for the reliability of the edge sealing of soft-pack batteries, but also has intuitiveness, reliability, rapid problem location, ease of operation, and economy, which helps to improve detection efficiency and accuracy.

[0047] In step S4, if it has been determined based on step S3 that there is leakage, that is, there are abnormal points in the battery, firstly, the aluminum film on the surface of the battery is dissolved based on the prepared sodium carbonate solution to expose the PP layer, so as to visually confirm the abnormal points. Place the battery cell that shows leakage in the test into a container filled with sodium carbonate solution, ensure that the aluminum film is completely immersed in the solution, and wait for a while until the aluminum film is completely dissolved. During the dissolution process, the aluminum and nylon layers in the aluminum film will be decomposed by the sodium carbonate solution, while the PP layer will be retained. When the water pressure test shows leakage, it means that the edge sealing may be false or other abnormalities. At this time, under appropriate lighting conditions, the retained PP layer can be checked by naked eye or using a two-dimensional device to visually determine whether there are abnormal phenomena such as false sealing, damage or bubbles. Strong alkalis and strong acids are used in traditional detection methods, but strong acids and strong alkalis have safety hazards and are relatively complicated to purchase and preserve; compared with traditional detection methods, this application uses sodium carbonate solution. Sodium carbonate is a commonly used chemical with a low price, which reduces the cost of the entire detection process. Figure 4-Figure 5 ,in, Figure 4 The picture shows that there is no abnormality in the PP layer after being immersed in the solution, that is, the battery will be sealed as "OK battery cell". Figure 5 The pictures of the abnormal false seal and abnormal position after soaking in the solution will be displayed, that is, the battery with the seal of "NG battery cell" will be displayed; dissolving the aluminum film in this step can locate the specific position of the edge sealing abnormality more quickly, which is helpful to adjust the production process in time and avoid quality problems in mass production. In addition, sodium carbonate solution is relatively safe for the human body, does not pose a safety hazard, and is highly environmentally friendly, easy to handle, and will not pollute the environment. In this step, the aluminum film is dissolved by using sodium carbonate solution, and the PP layer is retained, so that the abnormal points can be observed intuitively, thereby providing a basis for subsequent production line adjustments. It helps to quickly locate the problem and ensure quality control during the production process.

[0048] In one embodiment, the step of calculating the pressure parameter, the water injection volume parameter and the pressure holding time comprises:

[0049] S10, based on the preset fixed pressure parameters and fixed pressure holding time, verify the water pressure test results under different water injection volumes, and obtain the water injection volume coefficient;

[0050] S11, verifying the range of the pressure parameter by the water injection coefficient;

[0051] S12, verifying the pressure holding time range based on the pressure parameter range and the water injection coefficient;

[0052] S13. Based on the range of the pressure parameter, the water injection coefficient and the pressure holding time range, determine the pressure parameter, water injection parameter and pressure holding time applicable to the battery cell test water pressure.

[0053] In this embodiment, it is necessary to first determine the range of water injection volume, and verify the results of water pressure test under different water injection volumes by changing the water injection volume according to the preset fixed pressure parameters (e.g. 60Kg / cm2) and fixed pressure holding time (e.g. 4 minutes). Among them, the water injection volume parameter = the injection volume of the battery cell * the water injection coefficient. Since the injection volume involves confidential parameters, the water injection volume parameter is disclosed using the water injection volume coefficient. Therefore, in this embodiment, it is necessary to verify the specific water injection coefficient. The specific verification data is shown in the following table (where "OK battery cell" represents a normal battery cell, and "NG battery cell" represents an abnormal battery cell):

[0054]

[0055] It can be seen from the above table that when the water injection coefficient is 0.7-0.9 and the pressure is 60Kg / cm2, the normal battery cell water pressure is OK, and the abnormal battery cell water pressure is also OK, so the corresponding water injection coefficient of 0.7-0.9 is not applicable; when the water injection coefficient is 1.1-1.5, the pressure is 60Kg / cm2, the normal battery cell water pressure is OK, and the abnormal battery cell water pressure is NG, so the corresponding water injection coefficient of 1.1-1.5 is applicable; when the water injection coefficient is in the range of 1.7-1.9, the pressure is 60Kg / cm2, the normal battery cell water pressure is NG, the abnormal battery cell water pressure is NG, and the water injection coefficient of 1.7-1.9 is not applicable.

[0056] Therefore, by controlling the pressure at 60Kg / cm2 and the pressure holding time at 4min, changing the variable factor of water injection, the water injection coefficient is verified to be in the range of 1.1-1.5 and the pressure is 60Kg / cm2, which can normally test whether the battery cell has a false seal problem.

[0057] Through this step of verification, the water injection coefficient range is 1.1-1.5 times. Therefore, the water injection coefficient is controlled to be 1.1 times, the pressure holding time is 4 minutes, and the variable factor pressure is changed to verify the pressure parameters. The specific verification data is shown in the following table:

[0058]

[0059] It can be seen from the above table that when the pressure parameter range is 40-50Kg / cm2 and the water injection coefficient is 1.1, the normal battery cell water pressure is OK, and the abnormal battery cell water pressure is OK. Therefore, the pressure parameter with a pressure parameter range of 40-50Kg / cm2 is not applicable; when the pressure range is 60-80Kg / cm2 and the water injection coefficient is 1.1, the normal battery cell water pressure is OK, and the abnormal battery cell water pressure is NG. Therefore, the pressure parameter with a pressure parameter range of 60-80Kg / cm2 is applicable; when the pressure parameter is 90Kg / cm2 and the water injection coefficient is 1.1, the normal battery cell water pressure is NG, and the abnormal battery cell water pressure is NG. Therefore, the pressure parameter with a pressure parameter of 90Kg / cm2 is not applicable.

[0060] Through this step, it was verified that the water injection coefficient was controlled at 1.1 times and the pressure holding time was 4 minutes. By changing the variable factor pressure, it was verified that the pressure range of 60-80Kg / cm2 can normally test whether the battery cell has a false seal problem.

[0061] Since the first verification showed that the water injection coefficient ranged from 1.1 to 1.5 times, the water injection coefficient was controlled at 1.5 times and the pressure holding time was 4 minutes. The variable factors were changed for pressure verification to obtain the corresponding pressure parameters. The specific verification data are shown in the following table:

[0062]

[0063] As shown in the above table, when the pressure parameter is 40Kg / cm2 and the water injection coefficient is 1.5, the normal battery cell water pressure is OK, the abnormal battery cell water pressure is OK, and the parameters with a pressure parameter of 40Kg / cm2 are not applicable; when the pressure parameter range is 50-70Kg / cm2 and the water injection coefficient is 1.5, the normal battery cell water pressure is OK, the abnormal battery cell water pressure is NG, and the parameters with a pressure parameter range of 50-70Kg / cm2 are applicable; when the pressure parameter range is 80-90Kg / cm2 and the water injection coefficient is 1.5, the normal battery cell water pressure is NG, the abnormal battery cell water pressure is NG, and the parameters with a pressure parameter range of 80-90Kg / cm2 are not applicable.

[0064] Through this step, it was verified that by controlling the water injection coefficient by 1.5 times and the pressure holding time by 4 minutes, and changing the variable factor pressure, it was verified that the pressure range of 50-70Kg / cm2 can normally test whether the battery cell has a false sealing problem.

[0065] Through the above three verification results, it can be known that the water injection coefficient range is 1.1-1.5 times and the pressure range is 60-70Kg / cm2, which can normally test whether the battery cell has a false seal problem. Therefore, at this time, the water injection coefficient is controlled to be 1.1 times and the pressure is 60Kg / cm2, and the variable factor is changed to verify the pressure holding time. The specific verification data is shown in the following table:

[0066]

[0067] As shown in the above table, when the pressure parameter is 60Kg / cm2 and the water injection coefficient is 1.1 times, under the pressure holding time of 0.5min, the water pressure result shows that the water pressure of normal battery cells is OK, and the water pressure of abnormal battery cells is OK, so the corresponding pressure holding time of 0.5min is not applicable; under the pressure holding time of 1-3min, the water pressure result shows that the water pressure of normal battery cells is OK, and the water pressure of abnormal battery cells is NG, so the corresponding pressure holding time of 1-3min is applicable; under the pressure holding time of 4-5min, the water pressure result shows that the water pressure of normal battery cells is OK, and the water pressure of abnormal battery cells is NG, so the pressure holding time of 4-5min is applicable but the time is longer than 1-3min.

[0068] By controlling the water injection coefficient by 1.1 times and the pressure at 60Kg / cm2, and changing the variable factor pressure holding time, it is found that the pressure holding time range of 1-5min can normally test whether the battery cell has a false sealing problem. In order to shorten the verification time, 1-3min is selected to normally test whether the battery cell has a false sealing problem.

[0069] It is known that the water injection coefficient range is 1.1-1.5 times and the pressure range is 60-70Kg / cm2, which can normally test whether the battery cell has a false seal problem. Therefore, at this time, the water injection coefficient is controlled to be 1.5 times and the pressure is 70Kg / cm2, and the variable factor is changed to verify the pressure holding time. The specific verification data is shown in the following table:

[0070]

[0071] As shown in the above table, when the pressure parameter is 70Kg / cm2 and the water injection coefficient is 1.5 times, under the pressure holding time of 0.5min, the water pressure result shows that the water pressure of normal battery cells is OK, and the water pressure of abnormal battery cells is OK, so the corresponding pressure holding time of 0.5min is not applicable; under the pressure holding time of 1-3min, the water pressure result shows that the water pressure of normal battery cells is OK, and the water pressure of abnormal battery cells is NG, so the corresponding pressure holding time of 1-3min is applicable; under the pressure holding time of 4-5min, the water pressure result shows that the water pressure of normal battery cells is OK, and the water pressure of abnormal battery cells is NG, so the pressure holding time of 4-5min is applicable but the time is longer than 1-3min.

[0072] By controlling the water injection coefficient by 1.5 times and the pressure parameter to 70Kg / cm2, and changing the variable factor pressure holding time, it is verified that the pressure holding time range of 1-5min can normally test whether the battery cell has a false sealing problem. In order to shorten the verification time, 1-3min is selected to normally test whether the battery cell has a false sealing problem.

[0073] Therefore, through this embodiment, we can finally reach a pressure parameter range of 60-70Kg / cm2, a water injection coefficient of 1.1-1.5, and a pressure holding time range of 1-5min; preferably 1-3min. In the process of performing a water pressure test on the packaged battery cell based on the water pressure testing machine, the corresponding water injection parameter can be calculated based on the water injection coefficient, the actual pressure parameter used can be determined based on the range of the pressure parameter, and the actual pressure holding time used can be determined based on the range of the pressure holding time for the water pressure test.

[0074] This embodiment can more accurately identify edge sealing anomalies and improve detection accuracy by systematically verifying and adjusting test parameters. The optimal parameter combination can ensure the reliability of the test results and avoid misjudgment caused by inappropriate parameters. Once the optimal parameter combination is determined, a batch test process can be performed based on batteries of the same specifications, which can more quickly identify abnormal points, help to adjust the production process in a timely manner, and avoid quality problems in batch production.

[0075] In one embodiment, sodium carbonate is dissolved in a water solvent at 30° C. to 40° C. at a concentration of 0.94-0.1.44 mol / L to obtain the sodium carbonate solution.

[0076] In the present embodiment, sodium carbonate is dissolved in warm water at 30°C to 40°C. Warm water accelerates the dissolution of sodium carbonate and the reaction process with the aluminum film, and the concentration range is 0.94-1.44mol / L. Too low a concentration may affect the soaking cycle, and too high a concentration may cause the reaction to be too violent, increasing the safety risk. Among them, the amount of substance concentration of the required sodium carbonate is calculated, for example, when 150g of sodium carbonate is used, its molar mass is 106g / mol. By calculation, the amount of substance of sodium carbonate can be obtained (n=m / M=150g / 106g / mol≈1.44mol). Assuming that the solution volume is 1L, the amount of substance concentration is 1.44mol / L. The preparation process of sodium carbonate solution is simple, easy to operate, and reduces the difficulty of implementation. The sodium carbonate solution is easy to handle, does not pollute the environment, meets environmental protection requirements, and is low in price, which can reduce the cost of the entire detection process, and sodium carbonate has good thermal stability. When the water temperature is inconvenient to control within the specified range during operation, it has little effect on it.

[0077] In one embodiment, if the water pressure test result shows leakage, the step of using a sodium carbonate solution to dissolve the aluminum film of the packaged battery cell and determining the abnormal point based on the retained PP layer includes:

[0078] S30, if the water pressure test result shows leakage, the aluminum film is placed in a container containing the sodium carbonate solution for soaking, and the residual alkali solution on the surface of the packaged battery cell is rinsed after the aluminum film is completely dissolved;

[0079] S31. Under preset light conditions, use direct observation or two-dimensional method to determine abnormal points on the retained pp layer.

[0080] In this embodiment, when the water pressure test result shows that there is leakage, the water pressure test results include NG and OK; a battery cell with a normal seal will not be stretched and leak. If the seal edge is stretched and leaks, it means that there is an abnormality in the seal edge of the battery cell. As long as leakage occurs, the water pressure test result will show NG, indicating that the seal is abnormal. The aluminum film of the packaged battery cell is placed in a container containing sodium carbonate solution for soaking. The reaction principle is as follows: When the aluminum film (Al) is placed in a sodium carbonate (Na2CO3) aqueous solution, three different reaction steps actually occur: 1. First, sodium carbonate reacts with water to produce sodium hydroxide and carbon dioxide. The reaction equation is as follows: Na2CO3+H20→2NaOH+CO2(↑); 2. Then, aluminum reacts with sodium hydroxide and water to produce sodium aluminate and hydrogen. The reaction equation is as follows: Al+NaOH+2H2O→2NaAlO2+H2(↑); 3. Finally, sodium aluminate reacts with water and carbon dioxide to produce sodium carbonate and aluminum hydroxide white precipitate. The reaction equation is as follows: 2NaAlO2+CO2+3H2O→2Na2CO3+2Al(OH)3↓. After waiting for the aluminum film to completely dissolve, rinse the residual alkali solution on the surface of the packaged battery cell thoroughly with clean water. The purpose of this step is to remove the aluminum layer and nylon layer in the aluminum film and retain the PP layer for subsequent observation. The PP layer at the abnormal point will show bubbles or incomplete fusion. Under suitable light conditions, the specific abnormal points can be observed by naked eye, or the retained PP layer can be further checked by using a two-dimensional device to determine whether there are abnormal phenomena such as false sealing, damage or bubbles in the PP layer, so as to determine the abnormal points. Among them, "two-dimensional" refers to an instrument used for measurement and detection - a two-dimensional image measuring instrument. The two-dimensional image measuring instrument is a high-precision optical measuring device that can be used to detect various geometric parameters such as the size, shape, and angle of an object. This instrument captures the image of the object being measured through a camera, and then analyzes the image through software to obtain accurate measurement results. During the inspection of soft-pack batteries, the two-dimensional image measuring instrument can be used to observe and analyze the state of the PP layer to determine whether there are abnormal points, such as false sealing, damage or bubbles. This step can help quickly locate the specific location of the edge sealing abnormality and provide a basis for subsequent production line adjustments. Compared with traditional detection methods, using sodium carbonate solution to dissolve aluminum film can more quickly locate the specific location of the edge sealing abnormality, which helps to adjust the production process in time and avoid quality problems in mass production.

[0081] In one embodiment, the step of performing a hydrostatic test on the packaged battery cells using a hydrostatic tester includes: folding the battery cell air bag in half at a position equal to half the effective air bag width, and pressing the folded position tightly to place it under a pressure plate of the hydrostatic tester.

[0082] In this embodiment, the battery cells that have completed the second edge sealing 3 according to the requirements of step S2 are selected. An appropriate amount of tap water has been added to the inside of these battery cells, and the second sealing has been completed on one side of the air bag. The air bag of the battery cell is folded in half at half the effective width of the air bag. This is done to ensure that the edge sealing area is subjected to uniform pressure during the water pressure test. After folding in half, the folded position is pressed tightly to ensure that the battery cell remains stable during the water pressure test to avoid movement or deformation. Place the treated battery cell under the pressure plate of the water pressure tester, that is, place the battery cell between the upper pressure plate 4 and the lower pressure plate 5 of the water pressure tester, ensure that the battery cell is neatly arranged, and the edge sealing area is located under the pressure plate to ensure that the edge sealing area is subjected to uniform pressure during the water pressure test. It is convenient to set the water pressure tester according to the predetermined pressure parameters, water injection parameters and pressure holding time. Start the water pressure tester and let it test the battery cell according to the set parameters. This embodiment folds the battery cell airbag in half at half the effective airbag width, and presses the folded position under the pressure plate of the water pressure tester to ensure that the edge sealing area is subjected to uniform pressure during the water pressure test. This helps to more accurately detect whether there are abnormalities in the edge sealing, thereby providing a basis for subsequent abnormal point judgment. The folding and pressing of the battery cell can ensure the stability of the battery cell during the test and avoid misjudgment caused by movement or deformation of the battery cell.

[0083] In one embodiment, the water injection volume parameter is 1.1-1.5 times the water injection volume coefficient*battery cell liquid injection volume.

[0084] In this embodiment, the cell injection amount information of the cell is first obtained. The water injection amount parameter is the water injection amount coefficient * cell injection amount. According to the range of the water injection amount coefficient (1.1-1.5 times, inferred from experiments), the specific value of the water injection amount, i.e., the water injection amount parameter, is calculated, wherein the cell injection amount is the amount of electrolyte injected into the battery during the battery manufacturing process. This embodiment ensures that the cell is in a proper state during the water pressure test by adding an appropriate amount of water injection to the cell. The appropriate amount of water injection helps to improve the accuracy and reliability of the water pressure test and avoids misjudgment caused by improper dosage of the injected liquid. This allows for better identification of whether there is an abnormality in the edge sealing.

[0085] In one embodiment, the second edge sealing 3 includes using a packaging machine to perform a second sealing on one side of the cell air bag of the packaged cell; wherein the sealing position is 5-15 mm away from the upper edge of the air bag.

[0086] In this embodiment, a packaging machine is used to perform a second seal on one side of the air bag of the battery cell. The position of the secondary seal should be 5-15 mm away from the upper edge of the air bag, and the upper edge here should be a side edge on the battery cell air bag that is parallel and adjacent to the position of the secondary seal. At the same time, in order to ensure the sealing effect and seal strength, the seal can be repeated 2 to 3 times. After completing the secondary seal, check the appearance of the seal to ensure that the seal is wrinkle-free and undamaged, and that the seal thickness meets the standard before proceeding to the next step. This embodiment ensures the stability of the edge seal in the water pressure test and improves the accuracy of the detection by ensuring that the seal position is 5-15 mm away from the upper edge of the air bag. The secondary seal can ensure the integrity of the edge seal and avoid misjudgment due to poor edge sealing.

[0087] In one embodiment, the packaged battery cells include degraded bare cells or short-circuited bare cells.

[0088] In this embodiment, packaged cell samples are selected from the production line. These samples can be downgraded bare cells or short-circuited bare cells of the time period. Downgraded bare cells refer to bare cells that are found to have slight defects after X-ray inspection, but still have certain use value. These cells may not be suitable for final products due to some minor defects (such as slightly lower capacity, slightly poor consistency, etc.), but can still be used for other purposes or for testing. Short-circuited bare cells refer to bare cells in which internal short circuits occur during the production process. These cells cannot work normally or their performance is significantly reduced due to contact between internal components (such as positive and negative electrodes, diaphragms, etc.). The reason for selecting these samples is to ensure the timeliness of the detection and reduce cost losses. Using downgraded or short-circuited bare cells as samples can not only ensure the accuracy of the detection, but also avoid using high-quality cells for testing, thereby saving costs.

[0089] In one embodiment, the pressure parameter is 60-70 Kg / cm2.

[0090] In this embodiment, the pressure parameter range used in the water pressure test is 60-70Kg / cm2, which can ensure the accuracy and reliability of the test. Such a pressure range helps to more accurately detect whether there is an abnormality in the edge sealing, thereby providing a basis for subsequent abnormal point judgment.

[0091] In one embodiment, the holding time is 1-5 minutes.

[0092] In this embodiment, by determining the holding time range used in the water pressure test to be 1-5 minutes, the accuracy and reliability of the test can be ensured. In order to reduce the test time, it can be selected to be kept at 1-3 minutes. Such a holding time range helps to more accurately detect whether there is an abnormality in the edge sealing, thereby providing a basis for subsequent abnormal point judgment.

[0093] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for detecting and analyzing false seals on the seal edge of a soft-pack battery, characterized in that: include: Based on fixed pressure parameters and fixed holding time, calculate pressure parameters, water injection volume parameters and holding time; Based on the water injection amount parameter, liquid is added into the packaged battery cell, and a second edge is sealed on one side of the battery cell air bag of the packaged battery cell to which the liquid is added; Based on the pressure parameter and the pressure holding time, using a water pressure testing machine to perform a water pressure test on the packaged battery cell; If the water pressure test results show leakage, use sodium carbonate solution to dissolve the aluminum film of the packaged battery cell and determine the abnormal point based on the retained PP layer.

2. The method for detecting and analyzing false seals on the seal edge of a soft-pack battery according to claim 1, characterized in that: The step of calculating the pressure parameter, the water injection volume parameter and the pressure holding time comprises: Based on the preset fixed pressure parameters and fixed pressure holding time, verify the water pressure test results under different water injection volumes and obtain the water injection volume coefficient; Verify the range of pressure parameters by the water injection coefficient; Verifying the pressure holding time range based on the pressure parameter range and the water injection coefficient; Based on the range of the pressure parameters, the water injection coefficient and the pressure holding time range, the pressure parameters, water injection parameters and pressure holding time applicable to the battery cell test water pressure are determined.

3. The method for detecting and analyzing false seals on the seal edge of a soft-pack battery according to claim 1, characterized in that: Sodium carbonate is dissolved in a water solvent at 30° C. to 40° C. at a concentration of 0.94-0.1.44 mol / L to obtain the sodium carbonate solution.

4. The method for detecting and analyzing false seals on the seal edge of a soft-pack battery according to claim 1, characterized in that: If the water pressure test result shows leakage, the step of using a sodium carbonate solution to dissolve the aluminum film of the packaged battery cell and determining the abnormal point based on the retained PP layer includes: If the water pressure test result shows leakage, the aluminum film is placed in a container containing the sodium carbonate solution for soaking, and the residual alkali solution on the surface of the packaged battery cell is rinsed after the aluminum film is completely dissolved; Under the preset light conditions, the retained PP layer is directly observed or the two-dimensional method is used to determine the abnormal points.

5. The method for detecting and analyzing false seals on the seal edge of a soft-pack battery according to claim 1, characterized in that: The step of performing a water pressure test on the packaged battery cell by using a water pressure tester includes: folding the battery cell air bag in half at a position half the effective air bag width, and pressing the folded position tightly and placing it under a pressure plate of the water pressure tester.

6. The method for detecting and analyzing false seals on the seal edge of a soft-pack battery according to claim 2, characterized in that: The water injection amount parameter is 1.1-1.5 times the water injection amount coefficient*battery cell injection amount.

7. The method for detecting and analyzing false seals on the seal edge of a soft pack battery according to claim 1, characterized in that: The second edge sealing includes using a packaging machine to perform a second sealing on one side of the battery cell air bag of the packaged battery cell; wherein the sealing position is 5-15 mm away from the upper edge of the air bag.

8. The method for detecting and analyzing false seals on the seal edge of a soft-pack battery according to claim 1, characterized in that: The packaged cells include degraded bare cells or short-circuited bare cells during the period.

9. The method for detecting and analyzing false seals on the seal edge of a soft-pack battery according to claim 1, characterized in that: The pressure parameter is 60-70Kg / cm2.

10. The method for detecting and analyzing false seals on the seal edge of a soft-pack battery according to claim 1, characterized in that: The holding time is 1-5 minutes.

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