Diaphragm evaluation method for laminated battery and electronic equipment

Abstract

The invention provides a diaphragm evaluation method for a laminated battery and electronic equipment, and the diaphragm evaluation method for the laminated battery comprises the steps: evaluating a diaphragm, and judging whether the diaphragm has a damaged region or not; if the diaphragm has no damaged area, judging that the diaphragm is qualified; if the diaphragm has the damaged area, acquiring the area of the damaged area; judging whether the area of the damaged area is smaller than or equal to a critical threshold value of the damaged area corresponding to the diaphragm in the laminated battery; if yes, the diaphragm is judged to be qualified, if not, the diaphragm is judged to be unqualified, and the technical problem that in laminated battery diaphragm damage assessment, diaphragm damage and battery short circuit risks cannot be accurately and quantitatively assessed can be solved.

Description

Technical Field

[0001] This invention relates to the field of battery manufacturing technology, and in particular to a method for evaluating separators for stacked batteries and an electronic device. Background Technology

[0002] Stacked batteries are a common type of lithium-ion battery structure, typically composed of multiple positive electrode plates, negative electrode plates, and separators stacked alternately. The separator, acting as a physical barrier between the positive and negative electrodes, plays a crucial role in preventing internal short circuits. Damage to the separator can lead to direct contact between the positive and negative electrodes, causing an internal short circuit, and in severe cases, even thermal runaway, resulting in a safety accident.

[0003] In the manufacturing process of stacked batteries, the assessment of separator damage is particularly important. Existing studies on the correlation between separator damage and short-circuit resistance mostly rely on computer simulations. However, due to safety risks associated with experimental verification, the accuracy of these simulation results is difficult to fully verify, thus failing to provide a precise and quantitative assessment of the relationship between separator damage and battery short-circuit risk. Summary of the Invention

[0004] This invention provides a method and electronic device for evaluating separators used in stacked batteries, in order to improve the technical problem that it is impossible to accurately and quantitatively assess the risk of separator damage and battery short circuit in the evaluation of separator damage in stacked batteries.

[0005] This invention provides a method for evaluating separators used in stacked batteries, the method comprising:

[0006] The diaphragm is evaluated, and it is determined whether there are any damaged areas.

[0007] If there are no damaged areas on the diaphragm, the diaphragm is deemed qualified.

[0008] If the diaphragm has a damaged area, obtain the area of ​​the damaged area;

[0009] Determine whether the area of ​​the damaged region is less than or equal to the critical threshold for the damaged area of ​​the separator in the stacked battery.

[0010] If yes, the diaphragm is deemed qualified; otherwise, it is deemed unqualified.

[0011] In one embodiment of the present invention, the critical threshold for the damaged area of ​​the diaphragm is obtained by the following method:

[0012] Multiple damaged diaphragms are pre-obtained, each with a damaged area S. For each damaged area S:

[0013] The damaged diaphragm with a damaged area S is assembled into an equivalent single cell.

[0014] The measured short-circuit resistance R of the equivalent single cell was tested.

[0015] The damaged area S and its corresponding measured short-circuit resistance R were statistically analyzed, and an experimental dataset was constructed based on this.

[0016] The resistivity ρ of the damaged diaphragm at the location of the damage was obtained by fitting the experimental dataset. 破 The first mapping relationship between the damaged area S and the damaged area S;

[0017] Based on the pre-obtained resistance R of the laminate 总 The resistivity ρ_single of the corresponding equivalent single cell is obtained.

[0018] Let ρ 破 =ρ 单 The critical threshold S of the diaphragm damage area was obtained. 破 ;

[0019] The stacked battery includes an electrolyte and a stacked body formed by alternating stacking of multiple positive electrode sheets, multiple separators and multiple negative electrode sheets. The positive electrode sheet includes a positive current collector and a positive active material layer coated on both sides of the positive current collector. The negative electrode sheet includes a negative current collector and a negative active material layer coated on both sides of the negative current collector.

[0020] An equivalent single cell is predefined as the smallest cell unit that constitutes a stack, and a stack is defined as a combination of multiple equivalent single cells connected in parallel. Each equivalent single cell consists of a separator, a single-sided positive electrode and a single-sided negative electrode located on both sides of the separator, and an electrolyte. The single-sided positive electrode consists of a positive current collector with a thickness of 1 / 2 and a positive active material layer coated on its side facing the separator. The single-sided negative electrode consists of a negative current collector with a thickness of 1 / 2 and a negative active material layer coated on its side facing the separator.

[0021] In one embodiment of the present invention, a method for assembling a damaged separator with a damaged area S into an equivalent single-cell battery includes:

[0022] Obtain one single-sided positive electrode, one damaged separator, and one single-sided negative electrode;

[0023] A single-sided positive electrode, a damaged separator, and a single-sided negative electrode are stacked sequentially to form a battery cell.

[0024] The battery cells are subjected to hot pressing treatment, wherein the process parameters of the hot pressing treatment are configured to be consistent with the hot pressing parameters in the production process of stacked batteries;

[0025] The hot-pressed battery cells are immersed in an electrolyte that is configured to be consistent with the electrolyte used in the production process of stacked batteries, in order to obtain an equivalent single cell.

[0026] In one embodiment of the present invention, the method for detecting the measured short-circuit resistance R of an equivalent single-cell battery includes:

[0027] Place the equivalent single cell into the resistivity tester and adjust the position of the equivalent single cell so that the damaged area of ​​the damaged diaphragm is facing the tester and is located within the compression contact surface of the upper and lower probes.

[0028] Start the resistivity tester so that the upper and lower probes make direct electrical contact with both sides of the equivalent single cell under the applied preset pressure, and record the resistance value at this time as the measured short-circuit resistance R.

[0029] In one embodiment of the present invention, the resistivity ρ of the damaged diaphragm at the location of the damage is obtained by fitting an experimental dataset. 破 The first mapping relationship between the damaged area S and the damage area S includes:

[0030] A second mapping relationship between the short-circuit resistance R and the damaged area S of the damaged diaphragm was fitted based on the experimental dataset.

[0031] Based on the second mapping relationship, the resistivity ρ of the damaged diaphragm at the location of the damage is obtained. 破 The first mapping relationship between the damaged area S and the damaged area S.

[0032] In one embodiment of the present invention, the method for fitting a second mapping relationship between the short-circuit resistance R and the damaged area S of the damaged diaphragm based on experimental datasets is as follows:

[0033] For each group of damaged areas S and their corresponding R in the experimental dataset, standardization was performed:

[0034] Anomaly detection is performed on the damaged area S and its corresponding R to determine whether the damaged area S and / or R are outliers.

[0035] If so, delete the damaged area S and its corresponding R from the experimental dataset and continue with the next set of tests;

[0036] If not, proceed directly to the next set of tests;

[0037] The experimental dataset after outlier detection was normalized.

[0038] After the experimental dataset is detected to be standardized, the short-circuit resistance R and the damaged area S in the standardized experimental dataset are fitted using the least squares method to generate a second mapping relationship between R and S.

[0039] In one embodiment of the present invention, based on the pre-obtained resistance R of the laminated body 总 And the resistivity ρ of the corresponding equivalent single cell is obtained. 单 The process includes:

[0040] Pre-obtain the total resistance R of the stacked body 总 ;

[0041] Based on the total resistance R 总 The resistance R of an equivalent single-cell battery is obtained by combining the number of electrode groups N within the stacked cell and the number of positive electrodes M in each electrode group. 单 ;

[0042] Based on the resistance R of the equivalent single cell 单 The resistivity ρ of the equivalent single cell is obtained by considering the thickness L of the equivalent single cell. 单 .

[0043] In one embodiment of the present invention, the thickness of the equivalent single cell is L = T. 隔膜 +0.5T 正极 +0.5T 负极 ;T 隔膜 T represents the diaphragm thickness. 正极 T represents the thickness of the positive electrode. 负极 This represents the thickness of the negative electrode.

[0044] In one embodiment of the present invention, based on the total resistance R 总 The number of electrode groups N and the number of positive electrodes M in the electrode group are determined by the formula R. 单 =2R 总 *M*N obtains the resistance Rsingle of the equivalent single cell;

[0045] In an equivalent single-cell battery, the length of the positive electrode is D and the width is W. This can be determined using the formula ρ. 单 =2R 总 *M*N*(D*W) / (T 隔膜 +0.5T 正极 +0.5T 负极 The resistivity ρ of the equivalent single cell is obtained. 单 .

[0046] The present invention also provides an electronic device comprising: one or more processors and a storage device; the storage device being configured to store one or more programs, which, when executed by one or more processors, cause the electronic device to implement the separator evaluation method for stacked batteries as described above.

[0047] The beneficial effects of this invention are as follows: This invention proposes a method for evaluating the separator in stacked batteries. By comparing the area of ​​the damaged region with a defined critical threshold for the damaged area, it achieves a quantitative and objective assessment of the separator's safety status, overcoming the inaccuracies caused by reliance on subjective experience or unverified simulation data in traditional methods. This experimental verification method is direct and reliable, compensating for the limitations of simulation studies and providing a data foundation for research on the correlation between separator damage and short-circuit risk. It provides clear quality control standards and safety boundaries for the manufacturing process of stacked batteries, not only reducing the safety risk of internal short circuits caused by separator damage at the source but also facilitating the optimization of production processes and improving product qualification rates. Attached Figure Description

[0048] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0049] In the attached diagram:

[0050] Figure 1 This is a flowchart illustrating a method for evaluating separators for stacked batteries according to an embodiment of the present invention.

[0051] Figure 2 This is a flowchart illustrating step S4 of the method for evaluating separators for stacked batteries provided in one embodiment of the present invention.

[0052] Figure 3 This is a schematic diagram of the stacked body provided in one embodiment of the present invention when the damaged area of ​​the diaphragm does not cause a short circuit between the positive and negative electrodes.

[0053] Figure 4 This is a schematic diagram of the structure of the stacked body when the diaphragm damage area causes a short circuit between the positive and negative electrodes, according to one embodiment of the present invention.

[0054] Figure 5 This is a schematic diagram of an equivalent single-cell battery circuit provided in one embodiment of the present invention;

[0055] Figure 6 This is a schematic diagram of the structure of an equivalent single cell provided in one embodiment of the present invention;

[0056] Figure 7 This is a schematic diagram of the unfolded positive / negative electrode sheet provided in one embodiment of the present invention;

[0057] Figure 8 This is a flowchart illustrating step S41 of the method for evaluating separators for stacked batteries provided in one embodiment of the present invention.

[0058] Figure 9 This is a flowchart illustrating step S42 of the method for evaluating separators for stacked batteries provided in one embodiment of the present invention;

[0059] Figure 10 This is a flowchart illustrating step S421 of the method for evaluating separators for stacked batteries provided in one embodiment of the present invention.

[0060] Figure 11 This is a flowchart illustrating step S4211 of the method for evaluating separators for stacked batteries provided in one embodiment of the present invention.

[0061] Figure 12 This is a flowchart illustrating step S422 of the method for evaluating separators for stacked batteries provided in one embodiment of the present invention.

[0062] Figure 13 This is a flowchart illustrating step S43 of the method for evaluating separators for stacked batteries provided in one embodiment of the present invention.

[0063] Figure 14 This is a schematic diagram of a separator evaluation system for stacked batteries provided in one embodiment of the present invention;

[0064] Figure 15 This is a schematic diagram of an electronic device provided in one embodiment of the present invention.

[0065] The attached figures are labeled as follows:

[0066] 100. Stacked cell; 110. Positive electrode sheet; 111. Positive electrode current collector; 112. Positive electrode active material layer; 120. Negative electrode sheet; 121. Negative electrode current collector; 122. Negative electrode active material layer; 130. Separator; 140. Equivalent single cell; 141. Single-sided positive electrode sheet; 142. Single-sided negative electrode sheet; 150. Damaged separator; 200. Separator evaluation system for stacked cells; 210. Separator damage evaluation module; 220. Damage area acquisition module; 230. Judgment module; 1. Electronic device; 11. Storage device; 12. Processor. Detailed Implementation

[0067] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0068] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0069] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0070] The selection and design of the separator material directly impact battery performance. Currently, common lithium-ion battery separator material systems on the market include polyolefin-based separators, ceramic-coated separators, polymer-coated separators, and various novel composite separators. Polyolefin-based separators mainly include polyethylene (PE) and polypropylene (PP). Ceramic-coated separators refer to composite separators with an inorganic ceramic material (such as alumina, AlO; or boehmite, AlOOH) coating on the base membrane surface. These separators perform exceptionally well in high-temperature applications such as power batteries and energy storage batteries due to their excellent high-temperature resistance and good ionic conductivity. Polymer-coated separators include polyvinylidene fluoride (PVDF) coated separators and polymethyl methacrylate (PMMA) coated separators. Polyvinylidene fluoride (PVDF) separators are widely used in pouch cells that require high rate performance and long cycle life due to their excellent chemical stability and mechanical strength; while polymethyl methacrylate (PMMA) separators, with their good transparency and easy processing characteristics, have shown unique advantages in certain specific application areas.

[0071] However, even the most advanced separator materials may have defects or breakage risks. These microscopic or macroscopic defects can gradually amplify during battery use, eventually leading to battery performance degradation or even short circuits. Therefore, developing accurate and reliable methods for separator damage detection and prediction is of great significance for improving battery safety and reliability.

[0072] Please see Figures 1 to 13An embodiment of the present invention provides a method for evaluating the separator of a stacked battery. By comparing the area of ​​the damaged region with a determined critical threshold, the method achieves a quantitative and objective evaluation of the safety status of the separator 130, overcoming the inaccuracy problem caused by relying on subjective experience or unverified simulation data in traditional methods.

[0073] Please see Figure 1 The evaluation method for separators used in stacked solar cells includes the following steps:

[0074] S1. Evaluate the diaphragm 130 and determine whether it has any damaged areas. The evaluation can be performed using optical inspection equipment or other suitable inspection equipment to determine whether there are any breaks, perforations, or other defects on the surface of the diaphragm 130.

[0075] If there is no damaged area on diaphragm 130, please refer to Figure 6 If the condition is met, proceed to step S2 and determine that separator 130 is qualified. Qualified separator 130 can be used for the production and assembly of stacked batteries.

[0076] S3. If there is a damaged area on diaphragm 130, please refer to Figure 3 and Figure 4 The area of ​​the damaged region can then be obtained. The damaged area can be obtained by measuring the damaged portion of the diaphragm 130 using optical detection equipment, such as a charge-coupled device (CCD) optical microscope, and calculating the actual area value of the damaged region. It is understood that there can be one or more damaged areas on the diaphragm 130. If there is only one damaged area, its area is the area of ​​that single damaged area; if there are multiple damaged areas, their area is the sum of the areas of all damaged areas.

[0077] S4. Determine whether the area of ​​the damaged region is less than or equal to the critical threshold for the damaged area of ​​the separator 130 in the stacked battery. By comparing the actual damaged area with the predetermined critical threshold for the damaged area, the safety of the separator 130 in use is determined.

[0078] If the area of ​​the damaged region is less than or equal to the critical threshold for the damaged area of ​​the separator 130 in the stacked battery, then proceed to step S2 and determine that the separator 130 is qualified.

[0079] If the area of ​​the damaged region is greater than the critical threshold for the damaged area of ​​the separator 130 in the stacked battery, then step S5 is executed to determine that the separator 130 is unqualified.

[0080] This assessment method, by comparing the area of ​​the damaged region with a defined critical threshold for the damaged area, achieves a quantitative and objective evaluation of the safety status of the separator 130, overcoming the inaccuracies caused by reliance on subjective experience or unverified simulation data in traditional methods. This experimental verification method is direct and reliable, compensating for the limitations of simulation studies and providing a data foundation for research on the correlation between separator 130 damage and short-circuit risk. It provides clear quality control standards and safety boundaries for the manufacturing process of stacked solar cells, not only reducing the safety risk of internal short circuits caused by separator 130 damage from the source, but also facilitating the optimization of production processes and improving product yield.

[0081] Please see Figure 3 and Figure 4 In one embodiment of the present invention, the stacked battery includes an electrolyte and a stacked body 100 formed by alternatingly stacking a plurality of positive electrode plates 110, a plurality of separators 130, and a plurality of negative electrode plates 120.

[0082] Please see Figure 3 and Figure 4 The positive electrode 110 includes a positive current collector 111 and a positive active material layer 112 coated on both sides of the positive current collector 111. The positive current collector 111 is preferably aluminum foil; the positive active material layer 112 contains a positive active material, which can be selected from one or more of lithium cobalt oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, and their doped and modified materials.

[0083] Please see Figure 3 and Figure 4 The negative electrode 120 includes a negative electrode current collector 121 and a negative electrode active material layer 122 coated on both sides of the negative electrode current collector 121. The negative electrode current collector 121 is preferably copper foil; the negative electrode active material layer 122 contains a negative electrode active material, which can be selected from one or more of graphite, silicon-carbon composite material, silicon-oxygen composite material, lithium titanate and its doped and modified materials.

[0084] Please see Figure 3 and Figure 4 The separator 130 is disposed between the positive electrode 110 and the negative electrode 120 for electronic insulation and ion conduction. Its material can be selected from one or more of polyolefin microporous membranes (such as PE, PP), ceramic coated separators or polymer coated separators.

[0085] The electrolyte, comprising a lithium salt and an organic solvent, is filled in the stacked body 100. The lithium salt may be selected from lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, etc. The organic solvent is a mixture of cyclic and chain carbonates, wherein the cyclic carbonate may be selected from one or more of ethylene carbonate and propylene carbonate, and the chain carbonate may be selected from one or more of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0086] The stacked cell 100 is predefined as being composed of multiple equivalent single-cell batteries 140 connected in parallel. Please refer to [link to relevant documentation]. Figure 5 and Figure 6 The equivalent single-cell battery 140 consists of a separator 130, a single-sided positive electrode 141 and a single-sided negative electrode 142 located on both sides of the separator 130, and an electrolyte. The single-sided positive electrode 141 has a positive current collector 111 with a thickness of 1 / 2 and a positive active material layer 112 coated on its side facing the separator 130. The single-sided negative electrode 120 has a negative current collector 121 with a thickness of 1 / 2 and a negative active material layer 122 coated on its side facing the separator 130. It should be noted that the 1 / 2 thickness positive current collector 111 is half the original thickness of the positive current collector 111, and the 1 / 2 thickness negative current collector 121 is half the original thickness of the negative current collector 121.

[0087] Please see Figure 5 and Figure 6 A stacked battery is a complex system composed of dozens or even hundreds of electrode layers. Analyzing and calculating a single micrometer or millimeter-level breakage point in the separator 130 at the entire battery level is extremely difficult. Therefore, the stacked battery is decomposed into multiple equivalent single-cell batteries 140, resulting in a simplified model. This equivalent single-cell battery 140 simplifies the complex multilayer system into a single, fundamental unit. The equivalent single-cell battery 140 is a non-enclosed, uncharged test structure that allows for measurement or testing under absolutely safe conditions. The quality phenomenon of separator 130 breakage is linked to the safety risk of battery short circuit through a quantifiable criterion, enabling a quantitative and objective assessment of the safety status of the separator 130.

[0088] Please see Figures 2 to 6 In one embodiment of the present invention, the critical threshold for the damaged area corresponding to the diaphragm 130 is obtained by the following method:

[0089] S41. Pre-acquire multiple damaged diaphragms 150, each damaged diaphragm 150 having a damaged area S. For each damaged area S:

[0090] The damaged diaphragm 150 with a damaged area S is assembled into an equivalent single cell 140.

[0091] The measured short-circuit resistance R of the equivalent single cell 140 was tested;

[0092] The experimental dataset was constructed based on the statistical analysis of each damaged area S and its corresponding measured short-circuit resistance R.

[0093] Actual measurements yielded real-world data showing a one-to-one correspondence between the damaged area S and the short-circuit resistance R. This experimental dataset forms the cornerstone of the entire risk assessment method, ensuring that all subsequent calculations and judgments are based on verifiable and repeatable experimental data, rather than unproven assumptions or simulation results. It should be understood that this assessment method targets a diaphragm 130 of a specific thickness. Therefore, when constructing the dataset through experiments, multiple damaged diaphragms 150 with different damaged areas were used, with their thickness controlled to be the same as that of the diaphragm 130 to be evaluated, thus ensuring that all experiments and assessments were conducted under constant thickness conditions.

[0094] S42. Based on the experimental dataset, fit and obtain the resistivity ρ at the location of the damaged diaphragm 150. 破 The first mapping relationship between the damaged area S and the damaged area S.

[0095] Resistance R is an extrinsic parameter strongly correlated with the geometric dimensions and the area S of the damaged component. Resistivity ρ, on the other hand, is an intrinsic parameter describing the conductivity of a material and is theoretically independent of size. Through resistivity ρ... 破 The first mapping relationship between the damage area S and the resistance value is improved from the resistance value which is affected by various factors to the resistivity which better reflects the intrinsic conductivity of the damage point, thus improving the reliability of the evaluation results.

[0096] S43. Obtain the resistance R of the stacked body 100. 总 And the resistivity ρ of the corresponding equivalent single cell 140 was obtained. 单 .

[0097] By measuring the total resistance R of the stacked battery 总 Based on the equivalent single-cell 140 model, the readily obtainable macroscopic measurements are transformed into intrinsic parameters representing the conductivity characteristics of the battery's normal circuit, namely the resistivity ρ of the equivalent single-cell 140. 单 It provides a quantifiable scientific benchmark for the entire risk assessment system.

[0098] S44, let ρ 破 =ρ 单 The critical threshold S of the damaged area of ​​diaphragm 130 was obtained. 破 .

[0099] ρ 破 The resistivity at the diaphragm 130mm damage site is ρ. 单 For the equivalent single-cell battery to be evaluated with a 140mm separator and a 130mm resistivity, when ρ 破 <ρ 单 Electron transport will preferentially choose the damaged path with lower resistance, forming a short-circuit current. At this time, a short circuit occurs between the positive and negative terminals. Please refer to [link / reference needed]. Figure 4 When ρ 破 ≥ρ 单Electronic transmission still prioritizes the battery's normal circuit; the damaged area will not cause a short circuit. In this case, no short circuit has occurred. Please refer to [link / reference needed]. Figure 3 Therefore, when ρ 破 =ρ 单 At this point, S is the critical size that causes a short circuit between the positive and negative electrodes of the battery. The critical threshold S for the damaged area of ​​the separator 130 is calculated. 破 This provides a directly executable quantitative standard for quality inspection during the battery manufacturing process, greatly improving testing efficiency and reliability.

[0100] Please refer to the figure. Figure 8 In one embodiment of the present invention, the method of assembling the damaged separator 150 with a damaged area S into an equivalent single cell 140 in step S41 includes:

[0101] S411. Obtain a single-sided positive electrode 141, a damaged separator 150 and a single-sided negative electrode 142;

[0102] S412. A single-sided positive electrode 141, a damaged separator 150 and a single-sided negative electrode 142 are stacked in sequence to form a battery cell.

[0103] S413. Perform hot pressing treatment on the battery cell, wherein the process parameters of the hot pressing treatment are configured to be consistent with the hot pressing parameters in the production process of stacked batteries.

[0104] S414. The hot-pressed battery cell is immersed in an electrolyte, wherein the electrolyte is configured to be consistent with the electrolyte in the stacked battery production process, so as to obtain an equivalent single cell 140.

[0105] Please refer to the figure. Figure 8 In one embodiment of the present invention, the method for detecting the measured short-circuit resistance R of the equivalent single cell 140 in step S41 includes:

[0106] S415. Place the equivalent single cell 140 into the resistivity tester and adjust the position of the equivalent single cell 140 so that the damaged area of ​​the damaged diaphragm 150 is facing each other and located within the compression contact surface of the upper and lower probes.

[0107] S416. Start the resistivity tester so that the upper and lower probes make direct electrical contact with both sides of the equivalent single cell 140 under the condition of applying a preset pressure, and record the resistance value measured at this time as the measured short-circuit resistance R.

[0108] Please see Figure 9 In one embodiment of the present invention, S42, the resistivity ρ of the damaged diaphragm 150 at the damaged location is obtained by fitting the experimental dataset. 破 The first mapping relationship between the damaged area S and the damage area S includes:

[0109] S421. Fit the second mapping relationship between the short-circuit resistance R and the damaged area S of the damaged diaphragm 150 based on the experimental dataset.

[0110] S422. Based on the second mapping relationship, the resistivity ρ of the damaged diaphragm 150 at the damaged location is obtained. 破 The first mapping relationship between the damaged area S and the damaged area S.

[0111] Please see Figure 10 and Figure 11 In one embodiment of the present invention, S421, the method for fitting the second mapping relationship between the short-circuit resistance R and the damaged area S of the damaged diaphragm 150 based on the experimental dataset is as follows:

[0112] S4211. Standardize each damaged area S and its corresponding short-circuit resistance R in the experimental dataset: First, perform outlier detection on the selected damaged area S and its corresponding short-circuit resistance R to determine whether the damaged area S and / or R are outliers. If the damaged area S and / or R are outliers, delete the damaged area S and its corresponding short-circuit resistance R from the experimental dataset and continue to the next set of detections. If the damaged area S and / or R are not outliers, proceed directly to the next set of detections. Finally, normalize the experimental dataset after outlier detection. For the specific standardization process, please refer to [link to standardization procedure]. Figure 11 .

[0113] S4212. After the experimental dataset is detected to be standardized, the short-circuit resistance R and the damaged area S in the standardized experimental dataset are fitted using the least squares method to generate a second mapping relationship between R and S.

[0114] Considering that during actual sampling, the damaged area S and short-circuit resistance R may be affected by measurement errors, environmental interference, or equipment failures, causing individual samples to deviate from the normal distribution and thus affecting the accuracy of subsequent fitting, this invention also detects outliers in the experimental dataset and removes outlier combinations of damaged area S and corresponding short-circuit resistance R. Outliers refer to experimental data that significantly deviates from the overall data distribution or does not conform to the correspondence between damaged area S and short-circuit resistance R. Outliers include, but are not limited to, damaged area S exceeding a preset damaged area threshold; or short-circuit resistance R exceeding a preset resistance threshold; or inconsistent trends in the changes of damaged area S and short-circuit resistance R. Removing outliers from the experimental dataset effectively improves the reliability of the dataset, making subsequent fitting results more accurate. Furthermore, after outlier detection, the detected experimental dataset is normalized to eliminate differences between units and unify the data range.

[0115] As an optional implementation, linear normalization can be used to normalize the data for the damaged area S and the corresponding short-circuit resistance R in the experimental dataset. Specifically, for each influencing parameter (the influencing parameter is the damaged area S or the short-circuit resistance R), it can be linearly scaled based on its corresponding maximum and minimum values ​​in the experimental dataset, thereby mapping the value of the influencing parameter to a preset numerical range (such as [0, 1]), which greatly improves the subsequent fitting convergence speed.

[0116] As an alternative implementation, nonlinear normalization can be used to normalize the damaged area and corresponding short-circuit resistance in the experimental dataset. Specifically, based on the distribution characteristics of the influencing parameters (damaged area S or short-circuit resistance R), nonlinear normalization methods such as exponential normalization, logarithmic normalization, or tangent normalization can be used to map the influencing parameters, ensuring that the normalized parameters fall within a preset numerical range. This nonlinear normalization method allows for adaptive adjustment of the scaling ratio according to the data distribution characteristics, resulting in a more balanced data distribution.

[0117] It should be noted that linear normalization is computationally simple and efficient, while nonlinear normalization can adaptively adjust the scaling ratio and has a stronger ability to suppress uneven sample distribution. Those skilled in the art can adaptively choose the appropriate normalization method to normalize the experimental dataset based on actual needs; no limitations are imposed here.

[0118] In this embodiment, we take a Type A battery that conforms to the standards of the German Association of the Automotive Industry as an example. Please refer to [link to relevant documentation]. Figure 6 and Figure 7The basic design parameters of the electrode assembly are as follows: The positive electrode active material is a nickel-cobalt-manganese ternary material, where the molar ratio of nickel, cobalt, and manganese is approximately 8:1:1, and the total thickness of the positive electrode sheet 110 is 112 μm. The negative electrode active material is graphite, and the total thickness of the negative electrode sheet 120 is 142 μm; the separator 130 material is a polyethylene microporous membrane with a thickness of 9 μm. The electrolyte is a non-aqueous electrolyte containing lithium salt and organic solvent, wherein the organic solvent is composed of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), diethyl carbonate (DEC), and propylene carbonate (PC), with a volume ratio of DMC:EMC:EC:DEC:PC = 15:35:35:10:5. The electrode length D of the electrode assembly is 143 mm, the electrode width W is 83 mm, the number of electrode groups N inside the electrode assembly is 4, and the number of positive electrode sheets M in a single electrode group is 38.

[0119] Before mass production of the battery, test samples are constructed using the following steps: A test separator 130 with different damaged areas S is stacked with a single-sided positive electrode 141 and a single-sided negative electrode 142 to form an equivalent single-cell battery 140. (See [link to relevant documentation]). Figure 6 Subsequently, the short-circuit resistance R of each test sample under different diaphragm damage areas S was measured using a resistivity meter to form an experimental dataset. The experimental dataset was then standardized to obtain the dataset shown in Table 1.

[0120] Table 1. Short-circuit resistance R corresponding to different separator damage areas S under the same equivalent single cell thickness L.

[0121] <![CDATA[S(mm 2 )]]> L(μm) R(Ω) 0.032 137 964.63 0.046 137 559.7 0.09 137 204.5 0.15 137 95.0 0.36 137 25.6 0.82 137 4.1 1.3 137 3.73 2.6 137 1.32 6 137 0.38

[0122] In this embodiment, S4212, based on the least squares method, the short-circuit resistance R and the damaged area S in the standardized experimental dataset are fitted to generate a second mapping relationship between R and S. Based on this, an approximate function is fitted to the short-circuit resistance R and the damaged area S of the battery separator 130 under the condition that the thickness L of the equivalent single battery 140 is 137 μm: R = 5.5219 * S -1.5 (S is in mm) 2 (R is in Ω). It can be understood that the equivalent thickness of a single 140mm cell is L = T. 隔膜 +0.5T 正极 +0.5T 负极 The thickness L of the equivalent single cell 140 is consistent in each experimental dataset. When evaluating separators 130 with other thicknesses, experimental datasets of the equivalent single cell 140 under those thicknesses are obtained. After fitting these datasets, another approximate function relating the short-circuit resistance R to the damaged area S of the separator 130 is obtained. That is, the relationship R = 5.5219 * S.-1.5 The second mapping relationship varies with the thickness of the equivalent single cell 140, and needs to be refitted for different equivalent single cells 140.

[0123] Please see Figure 12 In one embodiment of the present invention, S422, according to the second mapping relationship, the resistivity ρ of the damaged diaphragm 150 at the damaged location is obtained. 破 The methods for establishing the first mapping relationship between the damaged area S and the damaged area S include:

[0124] S4221. Obtain the thickness L of the equivalent single cell 140, where L = T 隔膜 +0.5T 正极 +0.5T 负极 ;T 隔膜 For a diaphragm with a thickness of 130, T 正极 The positive electrode is 110mm thick, T 负极 The negative electrode sheet is 120mm thick.

[0125] S4222. By fitting the short-circuit resistance R and the damaged area S of the damaged diaphragm 150, the resistivity ρ of the damaged diaphragm 150 at the damaged location is obtained. 破 The first mapping relationship between the damaged area S and the damaged area. The second mapping relationship is expressed as R = f(S, T). 隔膜 If ) represents the first mapping relationship, then ρ is: 破 =f(S,T) 隔膜 )*S / (T 隔膜 +0.5T 正极 +0.5T 负极 ).

[0126] In this embodiment, the fitted second mapping relationship R = 5.5219*S -1.5 Substituting into the second mapping relationship, we obtain the relationship between the conductivity of the damaged diaphragm at 150° and the damaged area S of the diaphragm at 130°: ρ 破 =5.5219*S -1.5 *S / 137.

[0127] Please see Figure 13 In one embodiment of the present invention, S43, the resistance R of the stack 100 is obtained. 总 The resistivity ρ of the corresponding equivalent single cell 140 was obtained. 单 The process includes:

[0128] S431. Obtain the total resistance R of the laminate 100. 总 Total resistance R 总 The resistance was obtained through actual measurement using resistance testing methods. In this embodiment, the resistance R of model A battery was obtained through resistance testing methods. 总 =0.8mΩ.

[0129] S432, based on the total resistance R 总 And the number of electrode groups N within the stacked body 100, and the number M of positive electrode 110 in the electrode group, such as Figure 7 As shown, the resistance R of the equivalent single cell 140 is obtained. 单 .

[0130] In one embodiment of the present invention, based on the total resistance R 总 The number of electrode groups N within the stacked body 100 and the number of positive electrode 110 in the electrode group M are determined by formula R. 单 =2R 总 *M*N obtains the equivalent single-cell resistance R of 140. 单 .

[0131] S433, based on the resistance R of the equivalent single cell 140. 单 The resistivity ρ of the equivalent single cell 140 is obtained by considering the thickness L of the equivalent single cell 140. 单 .

[0132] In one embodiment of the present invention, the thickness L of the equivalent single cell 140 is T. 隔膜 +0.5T 正极 +0.5T 负极 ;T 隔膜 For a diaphragm with a thickness of 130, T 正极 The positive electrode is 110mm thick, T 负极 The negative electrode sheet is 120mm thick.

[0133] In one embodiment of the present invention, the length of the positive electrode 110 in the equivalent single-cell battery 140 is D and the width is W, which is determined by formula ρ. 单 =2R 总 *M*N*(D*W) / (T 隔膜 +0.5T 正极 +0.5T 负极 The resistivity ρ of the equivalent single cell 140 was obtained. 单 .

[0134] In this embodiment, the electrode assembly has an electrode length D of 143 mm, an electrode width W of 83 mm, and 4 electrode groups N within the assembly. Each electrode group contains 38 positive electrode sheets M. Based on the above data and the above method, we can deduce that ρ 单 = 2 * 0.8 * 4 * 38 * (143 * 83) / 137

[0135] And because ρ 破 =5.5219*S-1.5*S / 137, finally, according to S44, let ρ 破 =ρ 单The critical threshold S of the damaged area of ​​diaphragm 130 was obtained. 破 Let ρ 破 =ρ 单 The critical threshold S of the damaged area of ​​diaphragm 130 was calculated. 破 =0.00366mm 2 That is, when the damaged area S of the diaphragm 130 is greater than 0.00366 mm. 2 At this time, a short circuit may occur between the positive and negative electrodes due to diaphragm 130 rupture. This is possible when the ruptured area S of diaphragm 130 is ≤ 0.00366 mm². 2 At that time, there will be no situation where the diaphragm 130 is damaged and conducts a short circuit between the positive and negative poles.

[0136] Please see Figure 14 The present invention also provides a separator evaluation system 200 for stacked batteries. This system includes a separator damage evaluation module 210, a damage area acquisition module 220, and a judgment module 230. The separator damage evaluation module 210 is used to evaluate the separator 130 and determine whether the separator 130 is damaged. If the separator 130 has no damaged area, it is determined to be qualified. The damage area acquisition module 220 is used to acquire the area of ​​the damaged area when the separator damage evaluation module 210 detects a damaged area in the separator 130. The judgment module 230 is used to determine whether the area of ​​the damaged area is less than or equal to the critical threshold for the damaged area of ​​the separator 130. If so, the separator 130 is determined to be qualified; otherwise, it is determined to be unqualified.

[0137] Specific limitations regarding the separator evaluation system 200 for stacked solar cells can be found in the limitations of the separator evaluation method for stacked solar cells described above, and will not be repeated here. Each module in the aforementioned separator evaluation system 200 for stacked solar cells can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device in hardware format, or stored in the memory of a computer device in software format, so that the processor can call the corresponding operations of each module.

[0138] It should be noted that, in order to highlight the innovative aspects of this invention, this embodiment does not include modules that are not closely related to solving the technical problems proposed by this invention, but this does not mean that there are no other modules in this embodiment.

[0139] Please see Figure 15 The present invention also provides an electronic device 1, which may include a storage device 11, a processor 12 and a bus, and may also include a computer program stored in the storage device 11 and executable on the processor 12, such as a program for evaluating the separator of a stacked battery.

[0140] The storage device 11 includes at least one type of readable storage medium, including flash memory, portable hard drive, multimedia card, card-type memory (e.g., SD or DX memory), magnetic memory, magnetic disk, optical disk, etc. In some embodiments, the storage device 11 can be an internal storage unit of the electronic device 1, such as a portable hard drive of the electronic device 1. In other embodiments, the storage device 11 can be an external storage device of the electronic device 1, such as a plug-in portable hard drive, smart media card (SMC), secure digital (SD) card, flash card, etc., equipped on the electronic device 1. Furthermore, the storage device 11 can include both internal storage units and external storage devices of the electronic device 1. The storage device 11 can be used not only to store application software and various types of data installed on the electronic device 1, such as code for evaluating the separator of a laminated battery, but also to temporarily store data that has been output or will be output.

[0141] In some embodiments, the processor 12 may be composed of integrated circuits, such as a single packaged integrated circuit or multiple integrated circuits packaged with the same or different functions, including combinations of one or more central processing units (CPUs), microprocessors, digital processing chips, graphics processors, and various control chips. The processor 12 is the control unit of the electronic device 1, connecting various components of the electronic device 1 through various interfaces and lines. It executes various functions of the electronic device 1 and processes data by running or executing programs or modules stored in the storage device 11 (such as a separator evaluation program for stacked batteries) and calling data stored in the storage device 11.

[0142] The processor 12 executes the operating system of the electronic device 1 and various installed applications. The processor 12 executes the applications to implement the steps in the above-described method for evaluating separators for stacked batteries.

[0143] For example, a computer program may be divided into one or more modules, one or more of which are stored in storage device 11 and executed by processor 12 to complete this application. One or more modules may be a series of computer program instruction segments capable of performing specific functions, which describe the execution process of the computer program in electronic device 1. For example, the computer program may be divided into a diaphragm damage assessment module 210, a damage area acquisition module 220, and a judgment module 230.

[0144] The integrated unit implemented as a software functional module described above can be stored in a computer-readable storage medium, which can be non-volatile or volatile. The software functional module stored in the storage medium includes several instructions to cause a computer device (which may be a personal computer, computer equipment, or network device, etc.) or processor to execute some functions of the separator evaluation method for stacked batteries according to various embodiments of this application.

[0145] The beneficial effects of this invention are as follows: This invention proposes a method for evaluating the separator in stacked batteries. By comparing the area of ​​the damaged region with a defined critical threshold, it achieves a quantitative and objective assessment of the separator's safety status, overcoming the inaccuracies caused by reliance on subjective experience or unverified simulation data in traditional methods. It provides a direct and reliable experimental verification method for the field, effectively compensating for the limitations of simulation research and providing a data foundation for studying the correlation between separator damage and short-circuit risk. Furthermore, it provides clear quality control standards and safety boundaries for the manufacturing process of stacked batteries, not only reducing the safety risk of internal short circuits caused by separator damage at the source but also facilitating the optimization of production processes and improving product qualification rates.

[0146] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for evaluating separators used in stacked batteries, characterized in that, include: The diaphragm is evaluated, and it is determined whether the diaphragm has any damaged areas; If the diaphragm has no damaged areas, the diaphragm is deemed to be qualified. If the diaphragm has a damaged area, then the area of ​​the damaged area is obtained; Determine whether the area of ​​the damaged region is less than or equal to the critical threshold for the damaged area of ​​the separator in the stacked battery; If yes, the diaphragm is deemed qualified; otherwise, the diaphragm is deemed unqualified.

2. The diaphragm evaluation method according to claim 1, characterized in that, The critical threshold for the damaged area of ​​the diaphragm is obtained by the following method: Multiple damaged diaphragms are pre-obtained, each of which has a damaged area S. For each damaged area S: The damaged diaphragm with the damaged area S is assembled into an equivalent single cell. The measured short-circuit resistance R of the equivalent single cell was detected; The measured short-circuit resistance R of each damaged area S was statistically analyzed, and an experimental dataset was constructed accordingly. The resistivity ρ of the damaged diaphragm at the location of the damage was then fitted and determined based on the experimental dataset. 破 The first mapping relationship between the damaged area S and the damaged area S; Based on the pre-obtained resistance R of the stacked body 总 The resistivity ρ corresponding to the equivalent single cell is obtained. 单 ; Let ρ 破 =ρ 单 The critical threshold S of the damaged area of ​​the diaphragm was obtained. 破 ; The stacked battery includes an electrolyte and a stacked body formed by alternatingly stacking multiple positive electrode sheets, multiple separators, and multiple negative electrode sheets. The positive electrode sheet includes a positive current collector and a positive active material layer coated on both sides of the positive current collector. The negative electrode sheet includes a negative current collector and a negative active material layer coated on both sides of the negative current collector. The equivalent single cell is predefined as the smallest battery unit constituting the stack, and the stack is defined as being composed of multiple equivalent single cells connected in parallel. The equivalent single cell consists of a separator, a single-sided positive electrode and a single-sided negative electrode located on both sides of the separator, and an electrolyte. The single-sided positive electrode has a positive current collector with a thickness of 1 / 2 and a positive active material layer coated on its side facing the separator. The single-sided negative electrode has a negative current collector with a thickness of 1 / 2 and a negative active material layer coated on its side facing the separator.

3. The diaphragm evaluation method according to claim 2, characterized in that, A method for assembling the damaged separator having the damaged area S into an equivalent single-cell battery includes: Obtain one single-sided positive electrode, one damaged separator, and one single-sided negative electrode; The single-sided positive electrode, the damaged separator, and the single-sided negative electrode are stacked sequentially to form a battery cell. The battery cell is subjected to hot pressing treatment, wherein the process parameters of the hot pressing treatment are configured to be consistent with the hot pressing parameters in the production process of the stacked battery; The hot-pressed battery cells are immersed in an electrolyte, wherein the electrolyte is configured to be consistent with the electrolyte used in the production process of the stacked battery, in order to obtain the equivalent single cell.

4. The diaphragm evaluation method according to claim 2, characterized in that, The method for detecting the measured short-circuit resistance R of the equivalent single cell includes: Place the equivalent single cell into the resistivity tester, adjust the position of the equivalent single cell so that the damaged area of ​​the damaged diaphragm is facing the tester and located within the compression contact surface of the upper and lower probes. Start the resistivity tester so that the upper and lower probes make direct electrical contact with both sides of the equivalent single cell under a preset pressure, and record the resistance value measured at this time as the measured short-circuit resistance R.

5. The diaphragm evaluation method according to claim 2, characterized in that, The resistivity ρ of the damaged diaphragm at the location of the damage was obtained by fitting the experimental dataset. 破 The first mapping relationship between the damaged area S and the damaged area S includes: A second mapping relationship between the short-circuit resistance R and the damaged area S of the damaged diaphragm is fitted based on the experimental dataset. Based on the second mapping relationship, the resistivity ρ of the damaged diaphragm at the location of the damage is obtained. 破 The first mapping relationship between the damaged area S and the damaged area S.

6. The diaphragm evaluation method according to claim 5, characterized in that, The method for fitting the second mapping relationship between the short-circuit resistance R and the damaged area S of the damaged diaphragm based on the experimental dataset is as follows: For each group of damaged areas S and their corresponding R in the experimental dataset, the following standardization processing is performed: Anomaly detection is performed on the damaged area S and its corresponding R to determine whether the damaged area S and / or R are outliers. If so, delete the damaged area S and its corresponding R from the experimental dataset and continue with the next set of tests; If not, proceed directly to the next set of tests; The experimental dataset after outlier detection was normalized. After the experimental dataset is detected to be standardized, the short-circuit resistance R and the damaged area S in the standardized experimental dataset are fitted using the least squares method to generate a second mapping relationship between R and S.

7. The diaphragm evaluation method according to claim 2, characterized in that, Based on the pre-obtained resistance R of the stacked body 总 And the resistivity ρ of the corresponding equivalent single cell is obtained. 单 The process includes: The total resistance R of the stacked body is obtained in advance. 总 ; According to the total resistance R 总 The resistance R of the equivalent single-cell battery is obtained by combining the number N of electrode groups in the stack and the number M of positive electrodes in the electrode groups. 单 ; Based on the resistance R of the equivalent single cell 单 The resistivity ρ of the equivalent single-cell battery is obtained by taking the thickness L of the equivalent single-cell battery. 单 .

8. The diaphragm evaluation method according to claim 7, characterized in that, The thickness of the equivalent single cell is L = T 隔膜 +0.5T 正极 +0.5T 负极 ;T 隔膜 T represents the diaphragm thickness. 正极 T represents the thickness of the positive electrode. 负极 This represents the thickness of the negative electrode.

9. The diaphragm evaluation method according to claim 8, characterized in that, Based on the total resistance Rtotal, the number of electrode groups N in the stack, and the number of positive electrodes M in the electrode groups, the resistance Rsingle of the equivalent single cell is obtained by the formula Rsingle = 2Rtotal * M * N. The equivalent single-cell battery has a positive electrode plate with length D and width W, which is determined by the formula ρ. 单 =2R 总 *M*N*(D*W) / (T 隔膜 +0.5T 正极 +0.5T 负极 The resistivity ρ of the equivalent single cell is obtained. 单 .

10. An electronic device, characterized in that, The electronic device includes: One or more processors; A storage device for storing one or more programs, which, when executed by one or more processors, cause the electronic device to implement the separator evaluation method for stacked batteries as described in any one of claims 1 to 9.

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