Method and device for detecting pseudo soldering of cylindrical battery collector plate

Abstract

The invention provides a cylindrical battery collector plate pseudo soldering detection method and device, and relates to the technical field of battery detection, and the method comprises the steps: respectively obtaining empty electricity electrochemical data and full electricity electrochemical data of a cylindrical battery in an empty electricity state and a full electricity state; respectively calculating a first discrete score of the cylindrical battery in an empty electricity state and a second discrete score of the cylindrical battery in a full electricity state according to the empty electricity electrochemical data and the full electricity electrochemical data; and calculating a difference value between the first discrete score and the second discrete score, and outputting a detection result according to the difference value. The method has the beneficial effects that electrical performance detection is carried out on the cylindrical battery in the empty power state and the full power state, the cold solder joint of the battery can be judged according to the difference between electrochemical data obtained through testing in the two states of the cylindrical battery, the method is simple and efficient, cold solder joint judgment can be made without disassembling the battery, nondestructive detection is achieved, and the detection efficiency is improved. And the detection precision is higher than that of visual detection.

Description

Technical Field

[0001] The present invention relates to the technical field of battery detection, and particularly to a method and device for detecting the virtual soldering of a current collector plate of a cylindrical battery. Background Art

[0002] With the rapid development of the new energy vehicle industry, the power battery system is continuously evolving towards high energy density and high power density. In the field of cylindrical batteries, the traditional single tab structure has gradually been replaced by the full tab (also known as "tabless") technology. The full tab structure uses the entire edge of the positive and negative electrode plates as the current path, effectively shortening the electron transmission path, reducing the battery internal resistance and effectively improving the battery power density. However, in the full tab structure, the tabs on the edges of the positive and negative electrode plates are densely distributed at the upper and lower ends of the core after being wound with the electrode plates. After the densely distributed tabs are flattened or smoothed, they present a planar state. The tab surface in the planar state is connected to the current collector plate by welding, and the welding condition here has an important impact on the internal resistance and power cycle performance of the battery. Therefore, detecting the welding condition between the tab and the current collector plate is a crucial step in battery production.

[0003] The existing virtual soldering detection technologies for current collector plates are mainly visual detection and internal resistance detection. Among them, visual detection mainly judges the welding quality by visually identifying the welding condition of the welding points on the surface of the current collector plate. However, there are three major technical obstacles in actual applications: First, the welding interface is located at the contact surface between the tab and the current collector plate, and it is difficult for a conventional optical system to penetrate the metal surface to achieve internal observation; Second, welding spatter and metal oxide layers will cause optical interference. According to statistics, the misjudgment rate caused by this in mass production can reach 8%-15%; Third, the existing algorithms mainly identify virtual soldering features based on two-dimensional topography analysis, and cannot effectively distinguish real welding defects from surface contamination, making visual detection have a high misjudgment probability and low accuracy.

[0004] Internal resistance detection mainly screens by testing the internal resistance of the finished battery cells. However, since the internal resistance of the finished battery cells is affected by up to 17 parameters such as the electrolyte wetting degree, the state of the interface SEI film, and the electrode plate compaction density, it is impossible to fully correlate the battery cells with abnormal internal resistance with the virtual soldering battery cells, affecting the identification and judgment of virtual soldering battery cells.

[0005] Therefore, there is an urgent need for a method and device that can effectively detect the virtual soldering of the current collector plate of a cylindrical battery. Summary of the Invention

[0006] In view of the problems existing in the prior art, the present invention provides a method for detecting the virtual soldering of a current collector plate of a cylindrical battery, including:

[0007] Step S1, respectively obtaining the empty battery electrochemical data and full battery electrochemical data of the cylindrical battery in the empty battery state and the full battery state;

[0008] Step S2: Calculate the first discrete score of the cylindrical battery in the empty - charge state and the second discrete score in the full - charge state respectively based on the empty - charge electrochemical data and the full - charge electrochemical data.

[0009] Step S3: Calculate the difference between the first discrete score and the second discrete score, and output a detection result based on the difference.

[0010] Preferably, in step S1, the empty - charge electrochemical data and the full - charge electrochemical data are obtained during the formation stage in the manufacturing process of the cylindrical battery.

[0011] Preferably, step S2 includes:

[0012] Step S21: Add the empty - charge electrochemical data of multiple cylindrical batteries under the same production conditions to a first data set, and add the corresponding full - charge electrochemical data to a second data set.

[0013] Step S22: Calculate the first discrete score of each empty - charge electrochemical data in the first data set and the second discrete score of each full - charge electrochemical data in the second data set respectively.

[0014] Preferably, in step S22, the calculation formula for the discrete score is as follows:

[0015]

[0016] When p is the empty - charge electrochemical data, μ is the average value of all the empty - charge electrochemical data in the first data set, σ is the standard deviation of all the empty - charge electrochemical data in the first data set, and Z is the first discrete data;

[0017] When p is the full - charge electrochemical data, μ is the average value of all the full - charge electrochemical data in the second data set, σ is the standard deviation of all the full - charge electrochemical data in the second data set, and Z is the second discrete data.

[0018] Preferably, the empty - charge electrochemical data and the full - charge electrochemical data are ohmic internal resistance, or contact resistance, or contact inductance, or AC internal resistance.

[0019] The present invention also provides a detection device for the virtual soldering of the current collector plate of a cylindrical battery, which applies the above - mentioned detection method. The detection device includes:

[0020] A data collection module, configured to respectively obtain the empty - charge electrochemical data and the full - charge electrochemical data of the cylindrical battery in the empty - charge state and the full - charge state.

[0021] A data processing module, connected to the data collection module, is configured to calculate, based on the empty-cell electrochemical data and the full-cell electrochemical data respectively, a first discrete score of the cylindrical battery in the empty-cell state and a second discrete score of the cylindrical battery in the full-cell state;

[0022] A result output module, connected to the data processing module, is configured to calculate the difference between the first discrete score and the second discrete score, and output a detection result based on the difference.

[0023] Preferably, the empty-cell electrochemical data and the full-cell electrochemical data are obtained during the formation stage in the manufacturing process of the cylindrical battery.

[0024] Preferably, the data processing module includes:

[0025] A first processing unit, configured to add the empty-cell electrochemical data of multiple cylindrical batteries under the same production conditions to a first data set, and add the corresponding full-cell electrochemical data to a second data set;

[0026] A second processing unit, connected to the first processing unit, is configured to calculate the first discrete score of each empty-cell electrochemical data in the first data set and the second discrete score of each full-cell electrochemical data in the second data set respectively.

[0027] Preferably, the calculation formula of the discrete score is as follows:

[0028]

[0029] Wherein, when p is the empty-cell electrochemical data, μ is the average value of all the empty-cell electrochemical data in the first data set, σ is the standard deviation of all the empty-cell electrochemical data in the first data set, and Z is the first discrete data;

[0030] When p is the full-cell electrochemical data, μ is the average value of all the full-cell electrochemical data in the second data set, σ is the standard deviation of all the full-cell electrochemical data in the second data set, and Z is the second discrete data.

[0031] Preferably, the empty-cell electrochemical data and the full-cell electrochemical data are ohmic internal resistance, or contact resistance, or contact inductance, or AC internal resistance.

[0032] The above technical solution has the following advantages or beneficial effects: By utilizing the phenomenon that cylindrical batteries expand when fully charged and contract when discharged in the longitudinal direction, and considering that for a poorly soldered battery, due to the lack of a good soldering guarantee for contact between the current collector plate and the tab, there will be a significant difference in contact quality between the fully charged and discharged states. In the present invention, by detecting the electrical performance of cylindrical batteries in two states, namely discharged and fully charged, and using the difference between the electrochemical data obtained from the tests of the cylindrical batteries in these two states, it is possible to judge whether the battery is poorly soldered. This method is simple and efficient, enabling the determination of poor soldering without disassembling the battery, achieving non-destructive testing, and having a more accurate detection accuracy compared to visual inspection. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 In a preferred embodiment of the present invention, it is a schematic flow chart of a method for detecting poor soldering of the current collector plate of a cylindrical battery;

[0034] Figure 2 In a preferred embodiment of the present invention, it is a schematic sub-flow chart of step S2;

[0035] Figure 3 In a preferred embodiment of the present invention, it is a schematic diagram of the electrochemical impedance spectra of 150 cylindrical batteries in the discharged state;

[0036] Figure 4 In a preferred embodiment of the present invention, it is a schematic diagram of the electrochemical impedance spectra of 150 cylindrical batteries in the fully charged state;

[0037] Figure 5 In a preferred embodiment of the present invention, it is a distribution difference diagram of the ohmic internal resistance of some selected cylindrical batteries in the discharged state;

[0038] Figure 6 In a preferred embodiment of the present invention, it is a distribution difference diagram of the ohmic internal resistance of some cylindrical batteries in the fully charged state;

[0039] Figure 7 In a preferred embodiment of the present invention, it is a schematic structural diagram of a device for detecting poor soldering of the current collector plate of a cylindrical battery. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The present invention is not limited to this embodiment, and other embodiments may also fall within the scope of the present invention as long as they conform to the gist of the present invention.

[0041] In a preferred embodiment of the present invention, in view of the above problems existing in the prior art, a method for detecting poor soldering of the current collector plate of a cylindrical battery is provided, as Figure 1 shown, including:

[0042] Step S1: Obtain the empty - state electrochemical data and full - state electrochemical data of the cylindrical battery in the empty - battery state and full - battery state respectively.

[0043] Step S2: Calculate the first discrete score of the cylindrical battery in the empty - battery state and the second discrete score in the full - battery state respectively according to the empty - state electrochemical data and full - state electrochemical data.

[0044] Step S3: Calculate the difference between the first discrete score and the second discrete score, and output the detection result according to the difference.

[0045] Specifically, during the charge - discharge process of the cylindrical battery, due to the insertion / extraction of lithium ions in the graphite negative electrode, that is, there is a phenomenon of full - battery expansion and empty - battery contraction in the longitudinal direction of the cylindrical battery. For a battery with a defective virtual soldering of the current - collecting plate, the electrical contact characteristics at the contact interface between the tab and the current - collecting plate will show significant changes under mechanical stress cycling. Based on this, the present invention can judge the virtual soldering of the battery by detecting the electrical performance of the cylindrical battery in two states: empty - battery state and full - battery state. It is simple and efficient, can make a virtual soldering judgment without disassembling the battery, realizes non - destructive detection, and the detection accuracy is more precise than visual inspection.

[0046] More specifically, the present invention is applied to the production stage of cylindrical batteries. Considering that it is necessary to collect the empty - state electrochemical data and full - state electrochemical data of cylindrical batteries in the empty - battery state and full - battery state respectively, and combining with the fact that the grading stage in the manufacturing process of cylindrical batteries itself requires charging and discharging the batteries to count the battery capacity, initial efficiency, charging constant - current ratio, discharge platform voltage, and internal resistance for classification and matching. Therefore, in a preferred embodiment of the present invention, in step S1, the empty - state electrochemical data and full - state electrochemical data are obtained during the grading stage in the manufacturing process of cylindrical batteries. In other words, the collection stage of the empty - state electrochemical data and full - state electrochemical data for detecting the virtual soldering of the current - collecting plate is combined with the grading stage. For example, for a battery with a discharge current of 0.33C and an end - voltage state of 2.7V, after discharging to 2.7V (empty - battery) during grading and then standing for 2h, the empty - state electrochemical data can be collected. For a battery with a charging current of 0.33C, an end - voltage state of 4.2V, and an end - current state of 0.05C, after charging to 4.2V (full - battery) during grading and then standing for 1h, the full - state electrochemical data can be collected. There is no need to charge and discharge the cylindrical battery separately to collect the empty - state electrochemical data and full - state electrochemical data, effectively improving the test efficiency.

[0047] In a preferred embodiment of the present invention, the empty - state electrochemical data and full - state electrochemical data are ohmic internal resistance, or contact resistance, or contact inductance, or AC internal resistance.

[0048] Among them, the ohmic internal resistance, or contact resistance, or contact inductance of the cylindrical battery can be collected by obtaining the electrochemical impedance spectrum of the cylindrical battery, and an alternating current internal resistance meter can be used to collect the alternating current internal resistance of the cylindrical battery.

[0049] After collecting the empty-battery electrochemical data and full-battery electrochemical data of the cylindrical battery, calculate the corresponding discrete scores of the cylindrical battery in the empty-battery state and the full-battery state, and make the difference between the discrete scores, and then identify the solder joint voids based on the difference. Among them, as Figure 2 shown, the calculation process of the discrete score in step S2 includes:

[0050] Step S21, add the empty-battery electrochemical data of multiple cylindrical batteries under the same production conditions to the first data set, and add the corresponding full-battery electrochemical data to the second data set;

[0051] Step S22, calculate the first discrete score of each empty-battery electrochemical data in the first data set and the second discrete score of each full-battery electrochemical data in the second data set respectively.

[0052] In a preferred embodiment of the present invention, in step S22, the calculation formula of the discrete score is as follows:

[0053]

[0054] Among them, when p is the empty-battery electrochemical data, μ is the average value of all empty-battery electrochemical data in the first data set, σ is the standard deviation of all empty-battery electrochemical data in the first data set, and Z is the first discrete data;

[0055] When p is the full-battery electrochemical data, μ is the average value of all full-battery electrochemical data in the second data set, σ is the standard deviation of all full-battery electrochemical data in the second data set, and Z is the second discrete data.

[0056] Specifically, due to fluctuations in raw material batches between cylindrical batteries produced under different production conditions or in different batches (such as changes in the particle size distribution, specific surface area, impurity content, etc. of the active substances in the positive and negative electrode materials of different batches, which can lead to differences in lithium-ion diffusion coefficients, or minor adjustments in the lithium salt concentration and additive ratio in the electrolyte formulation, which can cause changes in the interfacial impedance, or differences in the roughness and ductility of the aluminum foil / copper foil used as the current collector material, affecting the contact resistance stability after tab welding), process parameter deviations (such as coating weight deviations during electrode manufacturing resulting in differences in the active substance loading, directly affecting the battery capacity and internal resistance, or fluctuations in the compaction density changing the porosity and causing changes in the resistance of the lithium-ion transmission path), etc., the electrochemical data of these cylindrical batteries in the empty and fully charged states may have significant differences, thus affecting the accuracy of open circuit detection. In this embodiment, it is preferably to collect all the cylindrical batteries with the same production conditions or in the same batch to complete the empty and fully charged electrochemical data, form a first data set and a second data set, and then analyze and obtain a first discrete score and a second discrete score based on the first data set and the second data set to ensure the accuracy of open circuit detection.

[0057] It can be understood that the more elements there are in the first data set and the second data set, the more accurate the analysis result. Therefore, when it is possible to ensure that cylindrical batteries in different batches have the same production conditions, cylindrical batteries in multiple batches can also be uniformly detected and analyzed to further improve the accuracy of open circuit detection.

[0058] As a preferred implementation method, taking the collection of the empty and fully charged electrochemical data of 150 cylindrical batteries as an example, as Figure 3 shown, it is a schematic diagram of the electrochemical impedance spectrum of 150 cylindrical batteries in the empty state. As Figure 4 shown, it is a schematic diagram of the electrochemical impedance spectrum of 150 cylindrical batteries in the fully charged state. Based on the above-collected electrochemical impedance spectra, the ohmic internal resistance of each cylindrical battery is obtained, and the ohmic internal resistances of some cylindrical batteries are selected for analysis to obtain the distribution difference diagram of the ohmic internal resistance in the empty state as Figure 5 shown, and the distribution difference diagram of the ohmic internal resistance in the fully charged state as Figure 6 shown. It can be clearly seen that the ohmic internal resistance of the batteries in the empty state is more discrete. In this embodiment, the distribution difference of the above-mentioned ohmic internal resistance is characterized by calculating the first discrete score and the second discrete score, and then the difference between the first discrete score and the second discrete score is compared with the corresponding preset threshold range to evaluate the open circuit situation.

[0059] The selection of the above-mentioned preset threshold range needs to be determined in combination with the results of sampling inspection. The following takes the ohmic internal resistance of the empty and fully charged electrochemical data as an example to illustrate the selection method of the preset threshold range:

[0060] First, 20 cylindrical batteries can be sampled and selected from the above 150 cylindrical batteries (this quantity is only for illustration and not a limitation of the present invention) for disassembly to check the actual soldering situation, and the ohmic internal resistance is detected to obtain the ohmic internal resistance values of the disassembled batteries when fully charged and discharged as shown in Table 1 below:

[0061] Table 1 Ohmic internal resistance values of the selected disassembled batteries when fully charged and discharged

[0062]

[0063]

[0064] In the above Table 1, the coding in the first column is the unique identity coding of each cylindrical battery, the second column is the ohmic resistance value in the discharged state, and the third column is the ohmic resistance value in the fully charged state. And after disassembly, it is found that the cylindrical batteries with the last four digits of the coding being "1589", "2301", "1175", "0310", "3040", "1037", "3240", "8524" have the phenomenon of current collector plate soldering joints being loose.

[0065] The following Table 2 shows the outlier values of the ohmic internal resistance of the selected disassembled batteries when fully charged and discharged. Among them, the coding in the first column is the unique identity coding of each cylindrical battery, the second column is the first discrete fraction of the ohmic resistance value in the discharged state, and the third column is the second discrete fraction of the ohmic resistance value in the fully charged state.

[0066] Table 2 Discrete fraction values corresponding to the ohmic internal resistance values of the selected disassembled batteries when fully charged / discharged

[0067]

[0068]

[0069] Based on Table 2 above, calculate the difference between the first discrete fraction and the second discrete fraction corresponding to each cylindrical battery, and calibrate the actual soldering situation of each cylindrical battery after disassembly to form Table 3 below.

[0070] Table 3 Difference in discrete fractions and actual soldering situation corresponding to the selected disassembled batteries

[0071]

[0072]

[0073] In the above Table 3, the coding in the first column is the unique identity coding of each cylindrical battery, the second column is the difference between the first discrete fraction and the second discrete fraction of each cylindrical battery, and the third column is the actual soldering situation obtained by checking after disassembly. Among them, 0 in the third column indicates no soldering joints being loose, and 1 indicates that there are soldering joints being loose.

[0074] From the comparative analysis of the above table, the preset threshold range can be set to less than 0, that is, when the Z-score of the difference between the first discrete score and the second discrete score is less than 0, it is output that there is a virtual soldering of the current collector plate in the cylindrical battery. Then, from the calculation results in the above table, it can be output that the current collector plates of the cylindrical batteries with the last four digits of the code being "1037", "0310", "1175", "2301", "3240", "8524", and "3040" have virtual soldering. Compared with the actual virtual soldering situation, only "1128" is misjudged as virtual soldering. It can be seen that the detection method for virtual soldering of the current collector plate of the cylindrical battery of the present invention has a high accuracy rate.

[0075] The above gives the selection method of the preset threshold range when the empty-cell electrochemical data and the full-cell electrochemical data are the ohmic internal resistance. The corresponding preset threshold ranges when the empty-cell electrochemical data and the full-cell electrochemical data are the contact resistance, or the contact inductance, or the alternating current resistance can be obtained in the same way and will not be elaborated here.

[0076] The present invention also provides a detection device for virtual soldering of the current collector plate of a cylindrical battery, which applies the above detection method. As Figure 7 shown, the detection device includes:

[0077] A data collection module 1, which is used to respectively obtain the empty-cell electrochemical data and the full-cell electrochemical data of the cylindrical battery in the empty-cell state and the full-cell state;

[0078] A data processing module 2, connected to the data collection module 1, which is used to respectively calculate the first discrete score of the cylindrical battery in the empty-cell state and the second discrete score of the cylindrical battery in the full-cell state according to the empty-cell electrochemical data and the full-cell electrochemical data;

[0079] A result output module 3, connected to the data processing module 2, which is used to calculate the difference between the first discrete score and the second discrete score, and output the detection result according to the difference.

[0080] In a preferred embodiment of the present invention, the empty-cell electrochemical data and the full-cell electrochemical data are obtained during the formation stage in the manufacturing process of the cylindrical battery.

[0081] In a preferred embodiment of the present invention, the data processing module 2 includes:

[0082] A first processing unit 21, which is used to add the empty-cell electrochemical data of multiple cylindrical batteries under the same production conditions to the first data set, and add the corresponding full-cell electrochemical data to the second data set;

[0083] A second processing unit 22, connected to the first processing unit 21, which is used to respectively calculate the first discrete score of each empty-cell electrochemical data in the first data set and the second discrete score of each full-cell electrochemical data in the second data set.

[0084] In a preferred embodiment of the present invention, the calculation formula for discrete scores is as follows:

[0085]

[0086] Wherein, when p is the open-circuit electrochemical data, μ is the average value of all open-circuit electrochemical data in the first dataset, σ is the standard deviation of all open-circuit electrochemical data in the first dataset, and Z is the first discrete data;

[0087] When p is the full-charge electrochemical data, μ is the average value of all full-charge electrochemical data in the second dataset, σ is the standard deviation of all full-charge electrochemical data in the second dataset, and Z is the second discrete data.

[0088] In a preferred embodiment of the present invention, the open-circuit electrochemical data and the full-charge electrochemical data are ohmic internal resistance, or contact resistance, or contact inductance, or AC internal resistance.

[0089] The above are only preferred embodiments of the present invention, and do not limit the implementation manners and protection scope of the present invention. For those skilled in the art, it should be realized that all equivalent replacements and obvious changes made by using the content of this specification and the drawings should be included in the protection scope of the present invention.

Claims

1. A detection method for the virtual soldering of a current collector plate of a cylindrical battery, characterized in that, Including: Step S1: Obtain the empty - state electrochemical data and full - state electrochemical data of the cylindrical battery respectively when the battery is in an empty - charge state and a full - charge state. Step S2: Calculate the first discrete score of the cylindrical battery in the empty - charge state and the second discrete score of the cylindrical battery in the full - charge state respectively according to the empty - state electrochemical data and the full - state electrochemical data. Step S3: Calculate the difference between the first discrete score and the second discrete score, and output a detection result according to the difference.

2. The detection method according to claim 1, wherein In step S1, the empty - state electrochemical data and the full - state electrochemical data are obtained during the grading stage in the manufacturing process of the cylindrical battery.

3. The detection method according to claim 1, characterized in that Step S2 includes: Step S21: Add the empty - state electrochemical data of multiple cylindrical batteries under the same production conditions to a first data set, and add the corresponding full - state electrochemical data to a second data set. Step S22: Calculate the first discrete score of each empty - state electrochemical data in the first data set and the second discrete score of each full - state electrochemical data in the second data set respectively.

4. The detection method according to claim 3, wherein In step S22, the calculation formula of the discrete score is as follows: Where, when p is the empty - state electrochemical data, μ is the average value of all the empty - state electrochemical data in the first data set, σ is the standard deviation of all the empty - state electrochemical data in the first data set, and Z is the first discrete data. When p is the full - state electrochemical data, μ is the average value of all the full - state electrochemical data in the second data set, σ is the standard deviation of all the full - state electrochemical data in the second data set, and Z is the second discrete data.

5. The detection method according to claim 1, characterized in that, The empty - state electrochemical data and the full - state electrochemical data are ohmic internal resistance, or contact resistance, or contact inductance, or AC internal resistance.

6. A detection device for the virtual soldering of a current collector plate of a cylindrical battery, characterized in that, Applying the detection method according to any one of claims 1 - 5, the detection device includes: A data collection module, configured to obtain the empty - state electrochemical data and the full - state electrochemical data of the cylindrical battery when the battery is in an empty - charge state and a full - charge state respectively. A data processing module, connected to the data collection module, and configured to calculate the first discrete score of the cylindrical battery in the empty - charge state and the second discrete score of the cylindrical battery in the full - charge state respectively according to the empty - state electrochemical data and the full - state electrochemical data. A result output module, connected to the data processing module, and configured to calculate the difference between the first discrete score and the second discrete score, and output a detection result according to the difference.

7. The detection device according to claim 6, characterized in that, The empty - state electrochemical data and the full - state electrochemical data are obtained during the grading stage in the manufacturing process of the cylindrical battery.

8. The detection device according to claim 6, wherein The data processing module includes: A first processing unit, configured to add the empty - state electrochemical data of multiple cylindrical batteries under the same production conditions to a first data set, and add the corresponding full - state electrochemical data to a second data set. A second processing unit, connected to the first processing unit, and configured to calculate the first discrete score of each empty - state electrochemical data in the first data set and the second discrete score of each full - state electrochemical data in the second data set respectively.

9. The detection device according to claim 8, characterized in that, The calculation formula for the discrete fraction is as follows: Where p is the empty cell electrochemical data, μ is the average value of all the empty cell electrochemical data in the first dataset, σ is the standard deviation of all the empty cell electrochemical data in the first dataset, and Z is the first discrete data; When p is the full cell electrochemical data, μ is the average value of all the full cell electrochemical data in the second dataset, σ is the standard deviation of all the full cell electrochemical data in the second dataset, and Z is the second discrete data.

10. The detection device according to claim 6, characterized in that, The empty cell electrochemical data and the full cell electrochemical data are ohmic internal resistance, or contact resistance, or contact inductance, or AC internal resistance.

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