Secondary cell tab tearing detection method, device, battery, system and equipment

Abstract

The invention relates to a secondary cell tab tearing detection method and device, a battery, a system and equipment. The method is applied to a secondary cell tab tearing detection device which is in contact connection with a to-be-detected secondary cell, the to-be-detected secondary cell is fixedly provided with a tab, and a double-electric-layer capacitor is formed between a positive electrode and a negative electrode of the to-be-detected secondary cell in an infiltrated electrolyte; the method comprises the steps that after a to-be-detected secondary cell is fully soaked in electrolyte, a first current test signal is applied to the to-be-detected secondary cell in a first target frequency interval, and a double-electric-layer capacitor is in an open-circuit state in the first target frequency interval; according to the first current test signal, testing a test resistance value of the secondary cell to be detected; and performing tab tearing detection on the to-be-detected secondary battery cell according to a size relationship between an actual resistance value obtained by calibration of the test resistance value in an actual test process and a preset resistance value. By adopting the method, the detection accuracy of tab tearing detection of the secondary battery cell is improved.

Description

Technical Field

[0001] The present application relates to the technical field of cell performance testing, and in particular, to a method and device for detecting ear tearing of secondary cell tabs, a secondary battery, an energy storage system, and an electrical equipment. Background Art

[0002] During the ultrasonic welding of multiple layers of current collectors in a secondary cell, due to the influence of welding stress, ear tearing may occur during the welding process due to reasons such as folding, wrinkling, and misalignment in the multiple layers of current collectors. Ear tearing can lead to burrs, abnormal protrusions, and fractures during subsequent assembly, thereby affecting the resistance value of the secondary cell. Therefore, it is very necessary to detect ear tearing of secondary cells.

[0003] Currently, during the detection of ear tearing of secondary cell tabs, the resistance value of the secondary cell is usually measured by a DCIR (Direct Current Internal Resistance) test device or an ACIR (Alternating Current Internal Resistance) tester, and then the ear tearing defect of the secondary cell is identified using the resistance value. However, the total impedance measured by the existing measurement method cannot reflect the actual resistance value of the secondary cell under specific conditions. Therefore, the detection result of the current ear tearing detection of secondary cells has the problem of low accuracy. Summary of the Invention

[0004] Based on this, it is necessary to provide a method and device for detecting ear tearing of secondary cell tabs, a secondary battery, an energy storage system, and an electrical equipment that can improve the detection accuracy of ear tearing detection of secondary cells for the above technical problems.

[0005] In a first aspect, the present application provides a method for detecting ear tearing of secondary cell tabs, which is applied to a device for detecting ear tearing of secondary cell tabs. The device for detecting ear tearing of secondary cell tabs is in contact connection with the secondary cell to be detected. The secondary cell to be detected is fixed with tabs, and the secondary cell to be detected includes a positive electrode and a negative electrode. A double-layer capacitor is formed between the positive electrode and the negative electrode in the infiltrated electrolyte. The method includes:

[0006] After the secondary cell to be detected is fully infiltrated with the electrolyte, a first current test signal is applied to the secondary cell to be detected within a first target frequency range, where the double-layer capacitor is in an open circuit state within the first target frequency range;

[0007] According to the first current test signal, the test resistance value of the secondary cell to be detected is measured;

[0008] An actual resistance value obtained by calibrating the test resistance value during the actual test process is determined, and based on the magnitude relationship between the actual resistance value and the preset resistance value, a tab tearing detection is performed on the secondary battery cell to be detected.

[0009] In a second aspect, the present application further provides a secondary battery cell tab tear detection device, the secondary battery cell tab tear detection device comprising a resistance measuring device and a host computer, the resistance measuring device and the secondary battery cell to be detected are contact-connected, the resistance measuring device and the host computer are communicatively connected, the host computer comprises an application module and a detection module, the secondary battery cell to be detected is fixed with a tab, the secondary battery cell to be detected comprises a positive electrode and a negative electrode, and a double-layer capacitor is formed between the positive electrode and the negative electrode in the infiltrated electrolyte; wherein,

[0010] The applying module is used to apply a first current test signal to the secondary battery cell to be detected within a first target frequency range after the secondary battery cell to be detected is fully immersed in the electrolyte, wherein the double-layer capacitor is in an open circuit state within the first target frequency range;

[0011] The resistance measuring device is used to test the test resistance value of the secondary battery cell to be tested according to the first current test signal;

[0012] The detection module is used to determine the actual resistance value of the test resistance value calibrated during the actual test process, and perform a tab tear detection on the secondary battery cell to be detected based on the size relationship between the actual resistance value and the preset resistance value.

[0013] In a third aspect, the present application further provides a secondary battery, comprising a secondary battery cell, wherein the secondary battery cell has no tab tearing, wherein the detection result of the secondary battery cell having no tab tearing is obtained by using the above secondary battery cell tab tearing detection method.

[0014] In a fourth aspect, the present application also provides an energy storage system, which includes the secondary battery as above.

[0015] In a fifth aspect, the present application also provides an electrical device, wherein the electrical device includes the energy storage system as described above.

[0016] The above-mentioned secondary battery cell pole ear tearing detection method, device, secondary battery, energy storage system and electrical equipment, from the perspective of the deployment of the secondary battery cell pole ear tearing detection device, the secondary battery cell pole ear tearing detection device is contact-connected with the secondary battery cell to be detected, and the secondary battery cell to be detected is provided with a positive electrode and a negative electrode, and a double-layer capacitor is formed between the positive electrode and the negative electrode of the secondary battery cell to be detected in the infiltrated electrolyte, and after the secondary battery cell to be detected is fully immersed in the electrolyte, the electrochemical reaction between the positive electrode and the negative electrode of the secondary battery cell to be detected is stable, which can objectively reflect the electrical properties of the secondary battery cell, and when the secondary battery cell pole ear device applies a first current test signal to the secondary battery cell to be detected within the first target frequency range, the double-layer capacitor is in an open-circuit state, thereby causing the impedance part of the double-layer capacitor in the circuit to be not ignored, so that the resistance change of the secondary battery cell under the polarization effect can be captured in real time, and the test resistance value of the secondary battery cell to be detected can be obtained by testing, and finally the actual resistance value obtained by calibrating the test resistance value in the actual test process. The relationship between the resistance value and the preset resistance value is used to detect the tab tearing of the secondary battery cell to be tested. Since the actual resistance value calibrated by the secondary battery cell tab tearing detection device fits the actual test process, and the resistance change of the secondary battery cell under the polarization effect can be measured, the actual resistance value can reflect the actual impedance of the secondary battery cell under a specific state. Finally, it is reliable to use the actual resistance value obtained by the detection as the basis for detecting the tab tearing of the secondary battery cell to be tested. Therefore, in the face of the complex internal resistance components of the secondary battery cell stationary in the electrolyte, and the DCIR device uses the charging and discharging characteristics of the secondary battery cell to complete the total impedance detection, and the polarization effect in the secondary battery cell will change with the change of the charging and discharging process, the use of the secondary battery cell tab tearing detection device can also overcome the technical defect that the total impedance measured by the DCIR device cannot reflect the actual resistance value of the secondary battery cell under a specific state. Therefore, the detection accuracy of the tab tearing detection of the secondary battery cell is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 Schematic diagram of a flow chart of a secondary battery cell tab tear detection method in one embodiment;

[0019] Figure 2 It is a first schematic diagram of a local process in a battery preparation process of a secondary battery cell tab tear detection method in one embodiment;

[0020] Figure 3 Schematic diagram of a test circuit of a secondary cell to be detected when the electric double - layer capacitors of the secondary cell ear tearing detection method in an embodiment are in different states;

[0021] Figure 4 Second schematic diagram of a local process in the battery preparation process of the secondary cell ear tearing detection method in an embodiment;

[0022] Figure 5 Third schematic diagram of a local process in the battery preparation process of the secondary cell ear tearing detection method in an embodiment;

[0023] Figure 6 Flow schematic diagram of the secondary cell ear tearing detection method in another embodiment;

[0024] Figure 7 Fourth schematic diagram of a local process in the battery preparation process of the secondary cell ear tearing detection method in another embodiment;

[0025] Figure 8 Partial module schematic diagram of the secondary cell ear tearing detection device in another embodiment. Detailed implementation manners

[0026] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0027] First, a secondary cell refers to a rechargeable cell that can be repeatedly charged and discharged. It has many characteristics such as repeatable charging and discharging, high energy density, energy conservation and environmental protection, and thus is widely used in many industries. Taking a lithium - ion battery encapsulated with a secondary cell as an example, in the lithium - ion battery industry, the multi - layer current collectors of lithium - ion batteries will have welding tear phenomena due to welding stress during the ultrasonic welding process, such as folding, wrinkling and misalignment in the multi - layer current collectors, resulting in burrs, abnormal protrusions and fractures during subsequent assembly processes, ultimately affecting the ohmic resistance value of the lithium - ion battery. Among them, the ohmic resistance value mainly refers to the resistance value composed of the electrode material, electrolyte, separator resistance and contact resistance of other parts. Currently, when detecting the welding tear phenomenon of lithium - ion batteries, the internal resistance value of the tested secondary cell is usually used as the detection basis, that is, when the internal resistance value of the tested secondary cell is too large, it is determined that the lithium - ion battery has an ear tear.

[0028] Secondly, it is understandable that the internal resistance of the secondary battery cell can be measured by a DCIR device or an ACIR tester. Compared with the DCIR device, the total impedance measured by the ACIR tester has higher accuracy and stability. Usually, the ACIR tester measures the impedance of the secondary battery cell by using a test frequency of 1kHz and an amplitude of 5mV. However, since the internal resistance of the secondary battery cell stationary in the electrolyte is complex, both the DCIR device and the ACIR tester use the total impedance detection of the secondary battery cell characteristics, and the polarization effect in the secondary battery cell will change with the change of the charging and discharging process. Therefore, the DCIR device is used to measure the total impedance of the secondary battery cell. The total impedance measured by the IR device or the ACIR tester cannot reflect the actual resistance value of the secondary battery cell in a specific state. Among them, the total impedance measured by the DCIR device or the ACIR tester is obviously unable to include the polarization resistance formed by the electrochemical reaction of the secondary battery cell, resulting in the detected internal resistance value of the secondary battery cell being smaller than the actual resistance value. Further, when the secondary battery cell is subjected to tab tear detection relying on the internal resistance value of the secondary battery cell, the secondary battery cell with tab tear phenomenon may be mistakenly detected as a good product. Therefore, there is an urgent need for a secondary battery cell tab tear detection method that can improve the detection accuracy of tab tear detection for secondary batteries.

[0029] In one embodiment, Figure 1 As shown, a secondary battery cell tab tear detection method is provided. In this embodiment, the method is applied to a secondary battery cell tab tear detection device as an example. The secondary battery cell tab tear detection device and the secondary battery cell to be detected are contact-connected. The contact connection method can be specifically that the secondary battery cell tab tear detection device establishes an electrical connection with the secondary battery cell to be detected through a test probe or a test clip, etc. The secondary battery cell tab tear device includes a resistance measuring device and a host computer, wherein the resistance measuring device and the host computer are communicatively connected, and the resistance measuring device is used to measure the test resistance value of the battery cell to be detected according to a first current test signal applied by the host computer. The host computer includes but is not limited to a laptop computer, a smart phone, and a tablet computer, etc. The host computer includes an application module and a detection module, and the application module is used to apply a first current test signal to the secondary battery cell to be detected within a first target frequency range, and the detection module is used to determine the actual resistance value calibrated during the actual test process, and perform tab tear detection on the secondary battery cell to be detected according to the relationship between the actual resistance value and the preset resistance value.

[0030] In the process of detecting the tab tearing of the secondary battery cell, certain detection conditions must be met among the tab, the secondary battery cell to be detected, the resistance measuring device and the host computer. First, the tab must be fixed to the secondary battery cell to be detected. The secondary battery cell to be detected includes a positive electrode and a negative electrode. Specifically, the tab can be welded to the positive electrode and the negative electrode of the secondary battery cell to be detected to achieve reliable connection between the battery cell to be detected and the external circuit. The secondary battery cell to be detected is immersed in an electrolyte, and a double-layer capacitor is formed between the positive and negative electrodes of the secondary battery cell to be detected in the immersed electrolyte. The formation of the double-layer capacitor is based on the double-layer theory. When the positive and negative electrodes of the secondary battery cell to be detected are immersed in the electrolyte, a tight charge layer will be formed on the electrode surface due to the interaction between the electrode surface and the electrolyte. This charge layer is composed of the charge on the electrode surface and the opposite ions in the electrolyte, which are tightly arranged by the Coulomb force, thereby forming a double-layer capacitor. At the same time When testing, it is necessary to ensure that the secondary battery cell to be tested is fully immersed in the electrolyte so that the secondary battery cell to be tested can undergo sufficient electrochemical reaction in the electrolyte, so that the polarization resistance value formed by the electrochemical reaction can accurately reflect the polarization impedance of the secondary battery cell to be tested, and then the upper computer controls the resistance measuring device to apply a first current test signal to the secondary battery cell to be tested within the first target frequency range, wherein the double-layer capacitor is in an open-circuit state within the first target frequency range, and then the secondary battery cell tab tearing detection device tests the test resistance value of the secondary battery cell to be tested based on the first current test signal, so that the test resistance value obtained by the test consists of two parts: the ohmic resistance value and the polarization resistance value, which can fit the actual application scenario, and then the upper computer determines the actual resistance value calibrated during the actual test process, and according to the relationship between the actual resistance value and the preset resistance value, the tab tearing detection is performed on the secondary battery cell to be tested.

[0031] On the one hand, since the secondary battery cell tab tear detection device can measure the resistance change of the secondary battery cell to be detected under the polarization effect, the measured test resistance value can more accurately reflect the actual impedance of the secondary battery cell under a specific state. On the other hand, since the actual resistance value is calibrated to fit the actual test process, the actual resistance value can fully and objectively reflect the actual impedance of the secondary battery cell to be detected under a specific state. Finally, it is reliable to use the actual resistance value obtained by detection as the basis for the tab tear detection of the secondary battery cell to be detected. Therefore, the detection accuracy of the tab tear detection of the secondary battery cell is improved. In this embodiment, the method includes the following steps 202 to 206. Among them:

[0032] Step 202, after the secondary battery cell to be detected is fully immersed in the electrolyte, a first current test signal is applied to the secondary battery cell to be detected within a first target frequency range, wherein the double-layer capacitor is in an open circuit state within the first target frequency range.

[0033] It should be noted that both the positive electrode and the negative electrode of the secondary battery cell to be detected are fixed with electrode tabs. The electrode tab tearing detection for the secondary battery cell to be detected can specifically be the tearing detection for the first electrode tab fixed to the positive electrode of the secondary battery cell to be detected, the tearing detection for the second electrode tab fixed to the negative electrode of the secondary battery cell to be detected, or the tearing detection for the first electrode tab and the second electrode tab. It can be understood that the secondary battery cell to be detected refers to the secondary battery cell waiting for electrode tab tearing detection. The positive electrode and the negative electrode of the secondary battery cell to be detected can be either a single-layer conductive sheet or a multi-layer current collector formed by multiple layers of conductive sheets. The conductive material can specifically be aluminum or copper, etc. The electrolyte for immersing the secondary battery cell to be detected can specifically be ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, or lithium hexafluorophosphate, etc. This embodiment does not make specific limitations in this regard. For example, in an implementable manner, both the positive electrode and the negative electrode of the secondary battery cell to be detected are composed of a layer of aluminum foil.

[0034] It should be noted that during the process of electrode tab tearing detection for the secondary battery cell to be detected, specific detection procedures will be set to ensure the quality control of the overall battery manufacturing process. For example, in an implementable manner, with reference to Figure 2 , Figure 2It is a first schematic diagram of a local process in the battery preparation process, wherein the secondary battery cell is first injected, and then subjected to high-temperature wetting and formation processes. After the formation process is completed, the electrolyte is wiped and high-temperature aging is performed in sequence. Further, the secondary battery cell is sequentially subjected to second injection, sealing pin welding, helium inspection, capacity division, first room temperature standing, first open circuit voltage (OCV) measurement, second room temperature standing, second open circuit voltage measurement, adjustment of state of charge (SOC), and third room temperature standing. After the third room temperature standing is completed, a DC internal resistance test process is set, that is, the internal resistance value of the secondary battery cell is measured by a DC internal resistance test device. It can be understood that the secondary battery cell in the DC resistance test stage can be referred to as a secondary battery cell to be tested. After the internal resistance value of the secondary battery cell to be tested is obtained by detection, the subsequent fourth room temperature standing, third open circuit voltage measurement, blue film wrapping, appearance inspection, sorting and warehousing processes are performed. It can be seen that in the DC resistance test stage, After the internal resistance value of the secondary battery cell to be tested is obtained by the DCIR device, the internal resistance value of the secondary battery cell to be tested can be used as a detection basis to detect the tearing of the secondary battery cell tabs manually or automatically. In the AC resistance test stage, a sinusoidal waveform excitation current can be applied to the secondary battery cell to be tested, and the internal resistance value of the secondary battery cell to be tested can be calculated based on the phase difference and amplitude of the measured current and voltage. The internal resistance value of the secondary battery cell to be tested can be used as a detection basis to detect the tearing of the secondary battery cell tabs.

[0035] It is understandable that there are obvious defects in the process of detecting the tearing of the tabs of the secondary battery cells to be tested in the traditional technology. The DCIR device or ACIR tester uses the charging and discharging characteristics of the secondary battery cells to complete the total impedance detection, and can only detect the ohmic resistance value of the secondary battery cells to be tested. The internal resistance value of the secondary battery cells to be tested immersed in the electrolyte is complex. In addition to the ohmic resistance value, there is also a polarization resistance value formed under the polarization effect. Since the polarization effect in the secondary battery cells to be tested will change with the changes in the charging and discharging process of the DCIR device or ACIR tester when testing the impedance of the secondary battery cells, it is impossible to accurately capture the polarization resistance value of the secondary battery cells to be tested, so that the total impedance measured by the DCIR device or ACIR tester cannot reflect the actual resistance value of the secondary battery cells in a specific state, and ultimately it is unreliable to use the resistance value measured by the DCIR device or ACIR tester as a detection basis for tab tear detection. Therefore, this embodiment provides another overall detection method for tab tear detection of the secondary battery cells to be tested.

[0036] It should be noted that the secondary battery cell to be tested is fully immersed in the electrolyte, which is a prerequisite for the tab tearing detection of the secondary battery cell to be tested. It can ensure that the electrochemical reaction of the positive and negative electrodes of the secondary battery cell to be tested is complete in the immersed electrolyte. Specifically, the partial process in the traditional battery preparation process can be used. For example, after the secondary battery cell completes the third room temperature standing process, it can be considered that the secondary battery cell has been fully immersed in the electrolyte. The partial process in the traditional battery preparation process can also be improved. For example, when the secondary battery cell is subjected to the third room temperature standing process, if the standing time reaches the preset time length, it is determined that the secondary battery cell has been fully immersed in the electrolyte. It can be understood that the preset time length is greater than the default standing time length set for the third room temperature standing in the traditional process.

[0037] It should be noted that the secondary battery cell to be tested can be contact-connected with the internal resistance measuring device of the secondary battery cell tab tearing detection device. After the secondary battery cell to be tested is fully immersed in the electrolyte, the upper computer can trigger the internal resistance measuring device through the application module to apply a first current test signal to the secondary battery cell to be tested within the first target frequency range, wherein the first current test signal is used to test the test resistance value of the secondary battery cell to be tested, and the first target frequency range refers to the frequency range that makes the double-layer capacitor in an open-circuit state. The internal resistance measuring device can specifically be a traditional ACIR tester, that is, an AC internal resistance tester. It can be understood that since the impedance characteristics of the double-layer capacitor will change with the frequency, the double-layer capacitor will present different states in current test signals in different frequency ranges. Specifically, under high-frequency current test signals, the capacitive reactance of the double-layer capacitor will be significantly reduced. After the capacitive reactance is reduced to a certain extent, the double-layer capacitor will be in a short-circuit state, and under low-frequency current test signals, the capacitive reactance of the double-layer capacitor is relatively large. After the capacitive reactance is increased to a certain extent, the double-layer capacitor will be in an open-circuit state.

[0038] Reference Figure 3 , Figure 3 Schematic diagram of the test circuit of the secondary cell to be tested when the double-layer capacitor is in different states, wherein (a) is a schematic diagram of the first test circuit of the secondary cell to be tested when the double-layer capacitor is in a short-circuit state, V1 is the voltage of the first test circuit, is the polarization resistance component in the first test circuit, is the electrolyte interface resistance component in the first test circuit, is the ohmic resistance component in the first test circuit, (b) is a schematic diagram of the second test circuit of the secondary cell to be tested when the double-layer capacitor is in an open circuit state, V2 is the voltage of the second test circuit, is the polarization resistance component in the second test circuit, is the electrolyte interface resistance component in the second test circuit, is the ohmic resistance component in the second test circuit. It can be understood that in the first test circuit, since the frequency of the first current test signal is high, and the double-layer capacitor C1 is in a short-circuit state, the measurement of the polarization resistance component will be ignored at this time, and the total internal resistance value detected by the secondary battery cell ear tear detection device is In the second test circuit, since the frequency of the first current test signal is low, the double-layer capacitor C2 is in an open circuit state, so the polarization resistance component is measured synchronously at this time, and the total internal resistance value detected by the secondary battery cell ear tear detection device is For example, in one practicable manner, a conventional AC internal resistance tester applies a 1KHz sinusoidal current test signal to the secondary cell to be tested to measure the impedance of the secondary cell to be tested. At this time, since the frequency of the sinusoidal current test signal is relatively large and is not within the first target frequency range, the internal test circuit of the secondary cell to be tested can refer to Figure 3 As shown in (a) in the figure, the polarization resistance value generated by the secondary battery cell to be detected under the polarization effect is not detected, which ultimately affects the detection accuracy of the secondary battery cell tab tearing detection. The secondary battery cell tab tearing detection device provided in this embodiment applies a 1Hz sinusoidal current test signal to the secondary battery cell to be detected. Since the frequency of the sinusoidal current test signal is small and is within the first target frequency range, the internal test circuit of the secondary battery cell to be detected can refer to Figure 3 As shown in (b), the polarization resistance value generated by the secondary battery cell to be tested under the polarization effect can be detected, and finally the total resistance value relied on for the tab tearing detection of the secondary battery cell is reliable.

[0039] As an example, step 202 includes: after the upper computer determines that the load adjustment of the secondary battery cell to be tested is completed, if it is detected that the standing time of the secondary battery cell to be tested at the first preset temperature is greater than the preset standing time, the upper computer selects the first target frequency within the first target frequency range, and controls the AC internal resistance tester to apply the first current test signal of the first target frequency to the secondary battery cell to be tested.

[0040] In one practicable manner, referring to Figure 4 , Figure 4 The second schematic diagram of a local process in the battery preparation process, wherein the DC internal resistance test process is replaced by the secondary battery cell tab tear detection process, that is, the secondary battery cell tab tear detection device provided by this embodiment replaces the traditional DC internal resistance test device to detect the total impedance of the secondary battery cell to be detected, and other processes in this local process can refer to the above explanation Figure 2The relevant content will not be repeated here. After the secondary battery cell is subjected to the pole ear tear detection by the secondary battery cell pole ear tear detection device, since the secondary battery cell pole ear tear detection device can provide conditions for accurately detecting the total impedance of the secondary battery cell to be detected, it can lay a foundation for improving the detection accuracy of the pole ear tear detection of the secondary battery cell.

[0041] It is understandable that, since the preparation process of secondary battery cells is complicated and requires a lot of manpower and material resources, if the tearing of the tabs of the secondary battery cells can be detected early, effective fool-proofing can be achieved in the battery preparation process, thereby reducing the preparation cost as much as possible. For example, the test device of the existing production line usually has many processes such as high-temperature wetting, formation and standing between the tab welding process and the capacity separation process. In the formation, capacity separation and standing processes, the total impedance of the secondary battery cells to be tested does not change significantly, and then the production line test process is optimized simultaneously. For example, in one feasible method, refer to Figure 5 , Figure 5 It is a third schematic diagram of a local process in the battery preparation process, wherein a secondary battery cell tab tearing detection process is set after high-temperature infiltration, that is, a secondary battery cell tab tearing detection device is set to measure the total impedance of the secondary battery cell to be detected, and the DC internal resistance test process originally located after the third normal temperature standing is cancelled, thereby advancing the detection process of secondary battery cell tab tearing detection, wherein, after the high-temperature infiltration process is completed, it is still necessary to set a standing time to ensure that the secondary battery cell to be detected is fully immersed in the electrolyte.

[0042] As another example, step 202 includes: after the host computer determines that the secondary battery cell to be tested has completed the infiltration at the second preset temperature, if it is detected that the standing time of the secondary battery cell to be tested at the third preset temperature is greater than the preset standing time, the host computer selects the first target frequency within the first target frequency range, and controls the resistance measuring device to apply the first current test signal of the first target frequency to the secondary battery cell to be tested, wherein the first preset temperature and the second preset temperature can be set to normal temperature, such as 25°C, and the third preset temperature can be set to high temperature, such as 50°C.

[0043] Step 204 : testing the test resistance value of the secondary battery cell to be tested according to the first current test signal.

[0044] It should be noted that when the resistance of the secondary battery cell to be tested is measured by the resistance measuring device, the first current test signal can be applied to the battery cell to be tested to obtain the test resistance value of the secondary battery cell to be tested in real time. It can be understood that the traditional DCIR device needs to be configured with a charging and discharging power supply module, for example, an independent power supply module is configured for each secondary battery cell channel, so that the current and voltage of the secondary battery cell to be tested can be measured, and finally the calculated ratio of the voltage drop and current before and after the test is used as the resistance value of the secondary battery cell to be tested. In this embodiment, the resistance value can be directly measured by contacting the test probe of the internal resistance measuring device with the battery cell to be tested, while the ACIR tester does not need to be configured with a charging and discharging power supply module. There are certain differences in the testing methods of the two. It can be understood that the principle of measuring the test resistance value of the secondary battery cell to be tested by the resistance measuring device can refer to the specific algorithm in the traditional technology, and this embodiment will not be repeated here.

[0045] As an example, step 204 includes: receiving a test resistance value of the secondary cell to be tested based on feedback of the first current test signal.

[0046] Step 206, determining an actual resistance value obtained by calibrating the test resistance value during the actual test process, and performing a tab tearing detection on the secondary battery cell to be tested according to the relationship between the actual resistance value and the preset resistance value.

[0047] It should be noted that due to the influence of objective environmental factors, the measured test resistance value may be different. Therefore, by performing test resistance value calibration processing, the stability of the impedance of the secondary battery cell to be tested can be ensured. After obtaining the actual resistance value, the tab tearing detection of the secondary battery cell to be tested can be completed based on the relationship between the actual resistance value and the preset resistance value. For example, in one feasible method, the preset resistance value is taken as 0.18. When the actual resistance value is greater than the preset resistance value, it is determined that the secondary battery cell to be tested has tab tearing. When the actual resistance value is less than or equal to the preset resistance value, it is determined that the secondary battery cell to be tested does not have tab tearing.

[0048] As an example, step 206 includes: according to the first current test signal, testing to obtain the first resistance value, the second resistance value and the third resistance value of the secondary battery cell to be tested, and obtaining the actual resistance value of the secondary battery cell to be tested by averaging the first resistance value, the second resistance value and the third resistance value, wherein the first resistance value, the second resistance value and the third resistance value are obtained by respectively testing the secondary battery cell to be tested by the first current test signal of the first target frequency applied at different time points, that is, the test resistance values ​​obtained by testing the internal resistance measuring device at different time points; and when it is detected that the actual resistance value is greater than the preset resistance value, it is determined that the secondary battery cell to be tested has a tab tear, and when it is detected that the actual resistance value is less than or equal to the preset resistance value, it is determined that the secondary battery cell to be tested does not have a tab tear.

[0049] It is understandable that the factors leading to poor self-discharge are not only the torn tabs, but also other adverse factors, such as pole piece burrs, internal metal foreign matter, internal micro short circuits, etc. Therefore, in order to determine whether the secondary battery cell to be tested has torn tabs, the battery components can also be disassembled to manually check the quality problems of the multi-layer current collector ultrasonic welding.

[0050] In the above method for detecting the tearing of the secondary battery tab, from the perspective of the deployment of the secondary battery tab tearing detection device, the secondary battery tab tearing detection device is in contact connection with the secondary battery to be detected. The secondary battery to be detected is provided with a positive electrode and a negative electrode. A double-layer capacitance is formed between the positive electrode and the negative electrode of the secondary battery to be detected in the infiltrated electrolyte. After the secondary battery to be detected is fully infiltrated in the electrolyte, the electrochemical reaction between the positive electrode and the negative electrode of the secondary battery to be detected is stable, which can objectively reflect the electrical performance of the secondary battery. When the secondary battery tab device applies a first current test signal to the secondary battery to be detected in the first target frequency range, the double-layer capacitance will be in an open circuit state, resulting in the impedance part of the double-layer capacitance in the circuit not being ignored. Thus, by capturing the change in the resistance of the secondary battery under the polarization effect in real time, the test resistance value of the secondary battery to be detected can be measured, and then the test resistance value in the actual test process can be calibrated. In this way, by applying the first current test signal with the same frequency to the secondary battery to be detected at different time points and calibrating the test resistance value obtained in the actual test process, the impedance error in the impedance detection process of the secondary battery to be detected caused by time change can be avoided, and thus the actual resistance value that can more accurately represent the impedance of the secondary battery to be detected can be obtained. Finally, the tearing of the tab of the secondary battery to be detected is detected based on the magnitude relationship between the actual resistance value calibrated in the actual test process through the test resistance value and the preset resistance value. Since the actual resistance value calibrated by the secondary battery tab tearing detection device conforms to the actual test process and can measure the change in the resistance of the secondary battery under the polarization effect, the actual resistance value can reflect the actual impedance of the secondary battery in a specific state. Finally, using the detected actual resistance value as the detection basis for detecting the tearing of the tab of the secondary battery to be detected is reliable. Therefore, in the case of complex internal resistance components of the secondary battery statically placed in the electrolyte and the DCIR device using the charge and discharge characteristics of the secondary battery to complete the total impedance detection, and the polarization effect in the secondary battery changing with the change of the charge and discharge process, etc., the secondary battery tab tearing detection device can also overcome the technical defect that the total impedance measured by the DCIR device cannot reflect the actual resistance value of the secondary battery in a specific state. Therefore, the detection accuracy of detecting the tearing of the tab of the secondary battery is improved.

[0051] In one embodiment, as Figure 6 shown, the actual test process includes a first test stage and a second test stage. The first test stage and the second test stage are tested with first current test signals of different frequencies. The test resistance value includes the first test resistance value measured in the first test stage and the second test resistance value measured in the second test stage. Determining the actual resistance value calibrated in the actual test process from the test resistance value includes:

[0052] Step 302 , detecting a first polarization resistance value of the secondary cell to be detected according to the first test resistance value and the ohmic resistance value of the secondary cell to be detected, and detecting a second polarization resistance value of the secondary cell to be detected according to the second test resistance value and the ohmic resistance value.

[0053] It should be noted that in the process of calibrating the test resistance value, the impedance of the double-layer capacitor will have the characteristic of changing with frequency. Therefore, the difference in the first current test signal input in different test stages during the actual test process will also make the impedance of the secondary battery cell to be tested measured by the resistance measuring device different. In order to avoid the frequency characteristic impedance error carried by the test resistance value obtained at different target frequencies within the first target frequency range, multiple test stages can be set in the actual test process, wherein different test stages are tested using different first current test signals, and then the polarization impedance of the secondary battery cell to be tested under the first current test signal of different frequencies can be detected, thereby laying the foundation for subsequent calibration to obtain the actual resistance value of the secondary battery cell to be tested, wherein the test resistance value includes the first test resistance value measured in the first test stage and the second test resistance value measured in the second test stage.

[0054] It should be noted that the ohmic resistance value can be stored in the host computer in advance, and can be specifically obtained by testing a traditional internal resistance measuring device. For example, in one feasible method, in the actual test process of testing the test resistance value of the secondary battery cell to be tested according to the first current test signal, it can be divided into a first test stage and a second test stage, wherein the first test stage is tested with a first current test signal of 1 Hz, and the second test stage is tested with a second current test signal of 0.9 Hz, so that the polarization resistance value of the secondary battery cell to be tested measured under the first current test signal of different frequencies can be detected through the first test resistance value and the second test resistance value obtained by testing in different test stages.

[0055] As an example, step 302 includes: extracting the ohmic resistance value of the secondary battery cell to be tested, subtracting the first test resistance value from the ohmic resistance value to obtain the first polarization resistance value of the secondary battery cell to be tested, and subtracting the second test resistance value from the ohmic resistance value to obtain the second polarization resistance value of the secondary battery cell to be tested.

[0056] Step 304 , calibrating the polarization resistance of the secondary battery cell to be tested during the actual test process according to the first polarization resistance value and the second polarization resistance value, to obtain a target polarization resistance value of the secondary battery cell to be tested.

[0057] It should be noted that in the process of calibrating the polarization resistance of the secondary battery cell during the actual test process, the same weight can be set by default for the polarization impedance conditions measured by the first current test signal at different frequencies, and the target polarization resistance value can be obtained by averaging different polarization resistance values. Alternatively, different weights can be set for the polarization impedance conditions measured by the first current test signal at different frequencies by analyzing the correlation between frequency and polarization resistance, and the target polarization resistance value of the secondary battery cell to be tested can be obtained through fusion calculation.

[0058] As an example, step 304 includes: performing averaging processing on the first polarization resistance value and the second polarization resistance value to obtain a target polarization resistance value calibrated during an actual test of the secondary battery cell to be tested.

[0059] As another example, step 304 includes: determining a first weight corresponding to the first polarization resistance value and a second weight corresponding to the second polarization resistance value, and obtaining a target polarization resistance value calibrated during the actual test process of the secondary battery cell to be tested by fusing the first polarization resistance value, the second polarization resistance value, the first weight and the second weight.

[0060] Step 306: taking the sum of the ohmic resistance value and the target polarization resistance value as the actual resistance value.

[0061] As an example, step 306 includes: summing the ohmic resistance value and the target polarization resistance value to obtain an actual resistance value.

[0062] In this embodiment, during the actual test process of the secondary battery cell to be tested, the actual test process is divided into a first test stage and a second test stage, and different first current test signals are used to test the secondary battery cell to be tested in different test stages to obtain a first test resistance value and a second test resistance value of the secondary battery cell to be tested, and then the first test resistance value and the second test resistance value are used to obtain a first polarization resistance value and a second polarization resistance value of the secondary battery cell to be tested under the first current test signal of different frequencies, so that the target polarization resistance value of the secondary battery cell to be tested is calibrated by the first polarization resistance value and the second polarization resistance value, and finally the actual resistance value is solved, so that the purpose of objectively representing the polarization resistance of the secondary battery cell to be tested under the first current test signal applied within the first target frequency range with the target polarization resistance value can be achieved, so as to obtain an accurate actual resistance value later, so as to lay a foundation for further improving the detection accuracy of tab tear detection of secondary battery cells.

[0063] In an practicable manner, the preset resistance value includes a first preset resistance value and a second preset resistance value, the first preset resistance value is smaller than the second preset resistance value, and the first preset resistance value is The second preset resistance is , and Respectively meet: , ; According to the relationship between the actual resistance value and the preset resistance value, the secondary battery cell to be tested is subjected to a tab tearing test, including:

[0064] After the secondary cell to be tested is formed, a second current test signal is applied to the secondary cell to be tested within the second target frequency interval, wherein the double-layer capacitor is in a short-circuit state within the second target frequency interval, and the first target frequency interval is , the second target frequency interval is ; According to the second current test signal, the charge and discharge resistance values ​​of the secondary battery cell to be detected are detected; the resistance difference between the actual resistance value and the charge and discharge resistance value is determined; if the resistance difference is less than the preset resistance difference threshold, then when it is detected that the actual resistance value is greater than the first preset resistance value, it is determined that the secondary battery cell to be detected has a tab tear, or when it is detected that the actual resistance value is less than or equal to the first preset resistance value, it is determined that the secondary battery cell to be detected does not have a tab tear; if the resistance difference is greater than or equal to the preset resistance difference threshold, then when it is detected that the actual resistance value is greater than the second preset resistance value, it is determined that the secondary battery cell to be detected has a tab tear, or when it is detected that the actual resistance value is less than or equal to the second preset resistance value, it is determined that the secondary battery cell to be detected does not have a tab tear.

[0065] It should be noted that, in order to further improve the detection accuracy of the tab tearing of the secondary battery cell to be tested, the AC internal resistance tester of the secondary battery cell tab tearing device can be used in different steps of the measurement process of the actual resistance value, wherein the charge and discharge resistance values ​​measured by the AC internal resistance tester before the secondary battery cell to be tested is formed are used to verify the stability of the internal resistance characteristics of the secondary battery cell to be tested during the actual test process, wherein the charge and discharge resistance values ​​refer to the quantitative values ​​of the resistance effect of the secondary battery cell to be tested on the current under specific charge and discharge conditions, and the specific charge and discharge conditions can specifically be specific charging conditions or specific discharge conditions, etc., so that the secondary battery cell tab tearing device can be detected. The actual resistance value and preset resistance values ​​of different sizes are used together as the basis for detecting the tearing of the secondary battery cell tab. For example, in one feasible method, assuming that the actual resistance value and the charge and discharge resistance value differ slightly, it indicates that the internal resistance characteristics of the actual resistance value are stable during the actual test process. In the actual test process, a smaller first preset resistance value is set as the judgment standard for the tab tearing situation. If the actual resistance value and the charge and discharge resistance value differ significantly, it indicates that the actual resistance value may have abnormal internal resistance during the actual test process. At this time, a larger second preset resistance value is set as the judgment standard for the tab tearing situation, thereby ensuring accurate classification of whether the secondary battery cell tab is torn or not.

[0066] It should be noted that the preset resistance value includes a first preset resistance value and a second preset resistance value, the first preset resistance value is less than the second preset resistance value, and the first preset resistance value is greater than 0.17 and less than 0.19 Any resistance value, the second preset resistance value is greater than 0.19 and less than 0.25 The second target frequency interval refers to the frequency interval that makes the double-layer capacitor in a short-circuit state. Specifically, the first target frequency interval is , the second target frequency interval is That is, the first target frequency selected in the first target frequency interval is any frequency not less than 0.1 Hz and not greater than 10 Hz, and the second target frequency selected in the second target frequency interval is any frequency greater than 10 Hz and not greater than 1050 Hz. In an practicable manner, referring to Figure 7 , Figure 7 It is the fourth schematic diagram of a local process in the battery preparation process, wherein a secondary battery cell pole ear tearing detection process is set after high-temperature infiltration, wherein the secondary battery cell pole ear tearing detection process is performed by a secondary battery cell pole ear tearing detection device using a first current test signal of 1 Hz to measure the total impedance of the secondary battery cell to be detected, and a DC internal resistance test process is set after the third normal temperature standing, and the DC internal resistance test process is performed by a DC internal resistance test device using a second current test signal of 1 kHz to measure the total impedance of the secondary battery cell to be detected. It can be understood that the DC internal resistance test process can also be set at any process position from after formation to before warehousing.

[0067] As an example, after the secondary battery cell to be tested is charged, if the static time of the secondary battery cell to be tested at the fourth preset temperature is greater than the preset static time, the second target frequency is selected within the second target frequency interval, and the AC internal resistance tester is controlled to apply a second current test signal to the secondary battery cell to be tested, wherein the double-layer capacitor is in a short-circuit state within the second target frequency interval, and the first target frequency interval is , the second target frequency interval is , the fourth preset temperature can specifically be 25°C; receiving the charge and discharge resistance value of the secondary battery cell to be detected based on the feedback of the second current test signal; subtracting the actual resistance value from the charge and discharge resistance value to obtain a resistance difference; if the resistance difference is less than the preset resistance difference threshold, then when it is detected that the actual resistance value is greater than the first preset resistance value, it is determined that the secondary battery cell to be detected has a tab tear, or when it is detected that the actual resistance value is less than or equal to the first preset resistance value, it is determined that the secondary battery cell to be detected does not have a tab tear; if the resistance difference is greater than or equal to the preset resistance difference threshold, then when it is detected that the actual resistance value is greater than the second preset resistance value, it is determined that the secondary battery cell to be detected has a tab tear, or when it is detected that the actual resistance value is less than or equal to the second preset resistance value, it is determined that the secondary battery cell to be detected does not have a tab tear.

[0068] In this embodiment, an AC internal resistance tester is set to test and obtain the charging and discharging resistance values ​​before the secondary battery cell to be tested is formed, and then the charging and discharging resistance values ​​are used to assist the secondary battery cell tab tear detection process in taking the actual resistance value as the detection basis, thereby ensuring that preset resistance values ​​of different sizes can be set for the actual resistance value as comparison objects in different situations, and then finally according to the size relationship between the actual resistance value and the preset resistance value, it is accurately detected whether the secondary battery cell to be tested has tab tearing. Therefore, a foundation is laid for further improving the detection accuracy of tab tear detection for secondary batteries.

[0069] In one embodiment, applying a first current test signal to a secondary cell to be tested within a first target frequency range includes:

[0070] Before the secondary battery cell to be tested is formed, an initial voltage value of the secondary battery cell to be tested immersed in the electrolyte is detected; after determining that the secondary battery cell to be tested is qualified based on the initial voltage value, a first current test signal is applied to the secondary battery cell to be tested within a first target frequency range.

[0071] It should be noted that a voltage measuring device may also be provided in the secondary battery cell tab tear detection device to detect the initial voltage value of the electrolyte before formation so as to prevent quality risks of the secondary battery cell to be tested. For example, in one feasible method, the voltage measuring device may specifically be a voltmeter. The voltmeter provided before formation is used to detect the initial voltage value of the secondary battery cell to be tested immersed in the electrolyte. When the voltage of the secondary battery cell to be tested is qualified, the upper computer controls the resistance measuring device to apply a first current test signal within the first target frequency range to the secondary battery cell to be tested. There is no need to perform tab tear detection on the secondary battery cell to be tested that does not meet the quality standards, thereby reducing the workload of performing tab tear detection on the secondary battery cell.

[0072] As an example, after the secondary battery cell to be tested is immersed in the electrolyte at high temperature, the initial voltage value of the secondary battery cell to be tested immersed in the electrolyte is detected by a voltmeter; if the initial voltage value is greater than a preset voltage threshold, it is determined that the secondary battery cell to be tested is qualified, and after the upper computer selects the first target frequency within the first target frequency range, the resistance measuring device is controlled to apply the first current test signal of the first target frequency to the secondary battery cell to be tested.

[0073] In this embodiment, a voltage measuring device is deployed in the secondary battery cell tab tearing device to detect the initial voltage value of the secondary battery cell to be tested immersed in the electrolyte, and based on the relationship between the initial voltage value and the preset voltage threshold, after it is determined that the secondary battery cell to be tested is qualified, a first current test signal is applied to the secondary battery cell to be tested within the first target frequency range, thereby avoiding the situation where invalid tab tearing detection is performed on the secondary battery cell to be tested. Therefore, while laying the foundation for improving the detection accuracy of tab tearing detection on secondary battery cells, the detection flexibility of secondary battery cell tab tearing detection is simultaneously improved.

[0074] In one embodiment, after performing a tab tearing detection on the secondary cell to be detected according to the magnitude relationship between the actual resistance value and the preset resistance value, the method further includes:

[0075] After the to-be-tested secondary cell has tab tearing, the total number of cells with tab tearing of the battery module to which the to-be-tested secondary cell belongs is detected; if the total number of cells with tab tearing is less than a preset total number threshold of cells, untested secondary cells are selected in the battery module as the to-be-tested secondary cells according to the cell identification information in the battery module; if the total number of cells with tab tearing is greater than or equal to the preset total number threshold of cells, an abnormal prompt message is output, wherein the abnormal prompt message is used to prompt that the batch of cells in the battery module have tab tearing.

[0076] It should be noted that in actual application scenarios, tab tear detection is usually performed on multiple secondary battery cells of a certain module. After detecting the tab tear condition of the current secondary battery cell to be detected, the object for tab tear detection can be replaced, and then after completing the tab tear detection of all secondary battery cells in the entire battery module, the total number of tab tear cells with tab tearing is counted, and the total number of tab tear cells is used as an indicator to control the quality of the battery preparation process. Among them, the abnormal prompt information is used to prompt that the batch of battery cells in the battery module has tab tearing, which can be specifically a sound prompt information or a text prompt information, etc. For example, in an implementable method, the upper computer monitors the test process of the battery module in real time, and classifies and counts the defective secondary battery cells. If secondary battery cells with poor internal resistance appear continuously during the test process, the upper computer controls the secondary battery cell tab tear detection device to trigger an abnormal alarm to prompt the abnormality of tab batch welding tearing.

[0077] As an example, after a secondary cell to be tested has torn tabs, the total number of cells with torn tabs in the battery module to which the secondary cell to be tested belongs is updated; if the total number of cells with torn tabs is less than a preset total number threshold of cells, then according to the cell identification information in the battery module, untested secondary cells are selected in the battery module as the secondary cells to be tested, and the step of applying a first current test signal to the secondary cell to be tested within a first target frequency range after the secondary cell to be tested is fully soaked in electrolyte and subsequent steps are returned to execute until all secondary cells in the battery module are selected as the secondary cells to be tested; if the total number of cells with torn tabs is greater than or equal to the preset total number threshold of cells, an abnormal prompt message is output, wherein the abnormal prompt message is used to prompt that there are torn tabs in a batch of cells in the battery module.

[0078] In this embodiment, by integrating the tab tear detection conditions of all secondary battery cells of the battery module to which the secondary battery cell to be detected belongs, the secondary battery cell tab tear detection process of the battery module is monitored in real time, and in the event of batch welding tearing abnormalities, timely warnings are given through abnormal prompt information, thereby achieving the purpose of effectively managing the tab tear detection conditions of batch battery cells in the battery module, thereby laying a foundation for improving the detection effect of secondary battery cell tab tear detection.

[0079] It should be understood that, although the steps in the flowcharts involved in the above embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above embodiments may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0080] Based on the same inventive concept, this embodiment also provides a secondary battery cell tab tear detection device for implementing the secondary battery cell tab tear detection method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more secondary battery cell tab tear detection device embodiments provided below can refer to the limitations of the secondary battery cell tab tear detection method above, and will not be repeated here.

[0081] In an exemplary embodiment, a secondary battery cell tab tear detection device is provided, comprising a resistance measuring device and a host computer, wherein the resistance measuring device and the secondary battery cell to be detected are contact-connected, the resistance measuring device and the host computer are communication-connected, the host computer comprises an application module and a detection module, the secondary battery cell to be detected is fixed with a tab, the secondary battery cell to be detected comprises a positive electrode and a negative electrode, and a double-layer capacitor is formed between the positive electrode and the negative electrode in the infiltrated electrolyte; wherein,

[0082] An application module, used for applying a first current test signal to the secondary battery cell to be tested within a first target frequency range after the secondary battery cell to be tested is fully immersed in the electrolyte, wherein the double-layer capacitor is in an open circuit state within the first target frequency range;

[0083] A resistance measuring device, used to test the test resistance value of the secondary battery cell to be tested according to the first current test signal;

[0084] The detection module is used to determine the actual resistance value of the test resistance value calibrated during the actual test process, and perform a tab tearing detection on the secondary battery cell to be tested based on the size relationship between the actual resistance value and the preset resistance value.

[0085] In one embodiment, the secondary battery cell tab tear detection device also includes a charge and discharge power supply module, which is contact-connected to the secondary battery cell to be detected, and the charge and discharge power supply module is used to detect the charge and discharge resistance value of the secondary battery cell to be detected based on a second current test signal applied to the secondary battery cell to be detected by the host computer within a second target frequency range.

[0086] It should be noted that, by setting an AC internal resistance tester to obtain the charging and discharging resistance value before the secondary battery cell to be tested is formed, and then using the charging and discharging resistance value to assist the secondary battery cell tab tear detection process in taking the actual resistance value as the detection basis, a charging and discharging power supply module can also be deployed in the secondary battery cell tab tear detection device. The charging and discharging power supply module can be contact-connected with the secondary battery cell to be tested through a test probe, etc. The charging and discharging power supply module is used to detect the charging and discharging resistance value of the secondary battery cell to be tested according to the second current test signal applied to the secondary battery cell to be tested by the host computer within the second target frequency range.

[0087] In one of the embodiments, the secondary battery cell tab tear detection device also includes a voltage measuring device, which is contact-connected to the secondary battery cell to be detected, and the voltage measuring device is used to detect the initial voltage value of the secondary battery cell to be detected when it is immersed in the electrolyte before the secondary battery cell to be detected is formed.

[0088] It should be noted that, in order to prevent quality risks of the secondary battery cells to be tested, a voltage measuring device can also be deployed in the secondary battery cell tab tearing detection device. The voltage measuring device is used to detect the initial voltage value of the secondary battery cells to be tested immersed in the electrolyte before the secondary battery cells to be tested are formed. Specifically, the voltage measuring device can be a voltmeter, and the voltage measuring device is contact-connected to the secondary battery cells to be tested through a test probe.

[0089] In one embodiment, the resistance measuring device is provided with a resistance test probe, and the voltage measuring device is provided with a voltage test probe, and the resistance test probe and the voltage test probe are isolated from each other by an insulator. The secondary battery cell ear tear detection device also includes a motion component, and the motion component includes a driving component, a guide component, a first positioning component and a supporting component. The battery module to which the secondary battery cell to be detected belongs is loaded on a loading platform, and the supporting component supports the loading platform. A second positioning component is provided on the loading platform. After the loading platform is located at the target position, the driving component drives the first positioning component and the second positioning component to perform positioning cooperation under the action of the guiding component, and after the positioning cooperation is completed, the resistance test probe contacts the first position of the positive electrode and the second position of the negative electrode respectively, and the voltage test probe contacts the third position of the positive electrode and the fourth position of the negative electrode respectively, wherein the first position, the second position, the third position and the fourth position are different from each other.

[0090] It should be noted that the resistance test probe and the voltage test probe are isolated by an insulator to prevent short circuit. Specifically, the insulator can be polytetrafluoroethylene or silicone. To facilitate users to view panel data on the secondary battery cell tab tearing detection device, a four-wire wiring method can be used to connect the secondary battery cell to be tested with the resistance measuring device and the voltage measuring device, respectively, wherein the resistance measuring device is an impedance tester, and the voltage measuring device is a voltmeter, and the voltmeter and the impedance tester are respectively fixed on the front direction of the secondary battery cell tab tearing detection device; in addition, the secondary battery cell tab tearing detection device is also provided with a motion component to meet the motion requirements of the secondary battery cell tab tearing detection device during actual testing.

[0091] In an practicable manner, the driving component may be a cylinder, the guiding component may be a guide column, the first positioning component may be a positioning pin, the supporting component may be a support rod, the carrying platform may be a tray, the battery module to which the secondary battery cell to be tested belongs is loaded in the tray, the tray is supported by the support rod, and a positioning hole (second positioning component) is provided on the tray. Under the control of the host computer, the motion component drives the tray to move to the target position, which may be a test start position specified by the user. After the target position, the cylinders on the left and right sides drive the positioning pins and the positioning holes to cooperate with each other under the action of the guide column to complete the positioning in the horizontal direction, wherein the resistance measuring device is contact-connected to the secondary battery cell to be tested carried on the tray through a resistance test probe, and the voltage measuring device is contact-connected to the secondary battery cell to be tested carried on the tray through a voltage test probe. The voltage test probe and the resistance test probe are both fixed on the fixed plate, and contact the positive and negative poles of the secondary battery cell to be tested through different positions to form a four-wire wiring method, thereby realizing the collection of the initial voltage value and the test resistance value, wherein the first position, the second position, the third position and the fourth position are different from each other.

[0092] It can be understood that, by means of the automated movement of the secondary battery cell tab tear detection device, a carrying platform is used to carry the battery module to which the secondary battery cell to be tested belongs. After the carrying platform moves into place, the secondary battery cell tab tear detection device can continuously perform tab tear detection on the secondary battery cells in the battery module without the need for the mechanism to move during the test, thereby avoiding the influence of movement on the accuracy.

[0093] In one embodiment, the secondary battery cell tab tear detection device also includes an information collector and a relay conversion board, which are respectively connected to the host computer for communication; wherein the information collector is used to collect the cell identification information in the battery module to which the secondary battery cell to be detected belongs, and send the cell identification information to the host computer, and the relay conversion board is used to convert the current test channel from the first target secondary battery cell to the second target secondary battery cell identified by the cell identification information according to the conversion instruction issued by the host computer, wherein the first target secondary battery cell and the second target secondary battery cell are different secondary batteries in the battery module.

[0094] It should be noted that the secondary battery cell tab tearing detection device also deploys an information collector and a relay conversion board, wherein the information collector is responsible for collecting the battery cell identification information, and the battery cell identification information can specifically be the battery cell number. The different secondary battery cells in the battery module can be accurately located through the battery cell identification information. The information collector can specifically be a scanner, and the relay conversion board is responsible for switching the current test channel between different secondary battery cells in the battery module. It can be understood that the first target secondary cell and the second target secondary cell can both be used as secondary cells to be tested at different time points of the secondary cell tab tearing detection.

[0095] In this way, compared with the traditional DCIR device that uses a moving mechanism to move the test probe, which results in relatively low efficiency in large-scale production, this embodiment selects a one-to-one correspondence between the number of secondary cells and the number of test probes. There is no need to move the probes, and the test channels are converted through an electronic relay conversion board. The conversion process is faster and more efficient than physically moving the probes.

[0096] Reference Figure 8 , Figure 8 The present invention is a partial module schematic diagram of a secondary battery cell pole ear tear detection device, wherein, in the module schematic diagram, the secondary battery cell pole ear tear detection device may specifically include a voltmeter 400, an AC impedance tester 401, a guide column 402, a cylinder 403, a conveyor line 404, a positioning pin 405, a positioning hole 406, a test probe 407, a relay conversion board 408, a tray 409, a scanner 410 and a host computer 411, wherein the test probe 407 may specifically include a voltage test probe 4071 and a current test probe 4072. The secondary battery cell 412 to be detected detected by the secondary battery cell pole ear tear detection device can not only detect the pole ear tear of any secondary battery cell in the battery module by taking the actual resistance value as the detection basis, but also control the pole ear tear situation and process of batch batteries in the battery module. Therefore, the secondary battery cell pole ear tear detection device provided in this embodiment can not only improve the detection accuracy of the secondary battery cell pole ear tear detection, but also improve the secondary battery cell The detection effect of the tab tearing detection, at the same time, by setting different types of test probes and forming a four-wire test method, respectively contacting the positive and negative poles of the secondary battery cell to be detected, the purpose of respectively collecting the initial voltage value and the test resistance value of the secondary battery cell to be detected can be achieved. At the same time, the current test channel is converted through the electronic relay conversion board, which can effectively improve the overall tab tearing detection efficiency of the battery module to which the secondary battery cell to be detected belongs. Moreover, relying on the automatic conveyor line and the method of loading a full tray of secondary batteries on a tray, after the secondary battery cell to be detected is in place, the secondary battery cell tab tearing detection device can continue to work to detect different secondary batteries in the battery module, thereby avoiding the situation where the secondary battery cell tab tearing detection device moves too much during the detection process. Therefore, it can also overcome the influence of the secondary battery cell tab tearing detection device on the test resistance value test accuracy of the secondary battery cell to be detected during the movement process, so the detection accuracy of the tab tearing detection of the secondary battery cell to be detected is further improved.

[0097] It can be understood that when different detection devices are used to detect secondary batteries with different capacities, the actual resistance values obtained by detecting different secondary batteries under different detection devices are different. Furthermore, the differences in the tearing conditions of the secondary cell tabs detected based on the actual resistance values exist. As shown in Table 1, Table 1 is a comparison table of the detection data of the AC resistance tester and the DC internal resistance test device, which are the detection devices for the tearing of the secondary cell tabs. Among them, Table 1 is as follows:

[0098] Table 1:

[0099]

[0100] It can be understood that in the traditional method, the AC resistance tester uses a 1 kHz current test signal to test the impedance of the secondary battery cell, while in this embodiment, the AC resistance tester uses a 1 Hz current test signal to test the impedance of the secondary battery cell. As can be seen from the test data shown in Table 1 above, in different secondary battery packs, there are differences in the measured resistance values under the same test method, which in turn leads to slight differences in the results of the secondary battery cell tab tear detection. In the same secondary battery pack, taking the resistance value measured by the AC resistance tester using a 1 Hz current test signal as the detection basis, the detection rate for 9120 secondary battery cells' tab tear conditions is 99.8%. Taking the resistance value measured by the AC resistance tester using a 1 kHz current test signal as the detection basis, the detection rate is 98.50%. Taking the resistance value measured by the current test signal of the DC internal resistance tester as the detection basis, the detection rate is 97.20%. Therefore, the secondary battery cell tab tear detection device adopted in this embodiment has higher accuracy compared to the traditional secondary battery cell tab tear detection methods. Specifically, when comparing the impedance test methods of the same type of secondary battery cells, since the impedance test of the secondary battery cells using a 1 Hz current test signal can more truly reflect the actual impedance of the secondary battery cells compared to the impedance test of the secondary battery cells using a 1 kHz current test signal, it significantly improves the accuracy of the overall secondary battery cell tab tear detection of the battery pack. When comparing different types of secondary battery cell impedance test methods, the impedance test of the secondary battery cells using a 1 Hz current test signal can also more truly reflect the actual impedance of the secondary battery cells compared to the impedance test of the secondary battery cells using the DC internal resistance test device, which to a certain extent improves the accuracy of the overall secondary battery cell tab tear detection of the battery module. At the same time, although the DC internal resistance test device can relatively accurately detect the overall secondary battery cell tab tear of the battery pack, in the secondary battery cell tab tear detection device of this embodiment, since the impedance test of the secondary battery cells using a 1 Hz current test signal has a relatively early test process, it can prevent the occurrence of cost consumption caused by detecting the secondary battery cell tab tear phenomenon in the later process. Therefore, it can achieve the purpose of effectively preventing the tab welding tear phenomenon of the battery pack, and improves the detection effect of the secondary battery cell tab tear detection from multiple dimensions such as detection cost and detection accuracy.

[0101] Each module in the above secondary battery cell tab tear detection device can be implemented in whole or in part by software, hardware, and their combinations.

[0102] In one embodiment, a secondary battery is further provided. The secondary battery includes a secondary battery cell. The secondary battery cell has no tab tearing. The detection result of the secondary battery cell having no tab tearing is obtained by the above-mentioned secondary battery cell tab tearing detection method.

[0103] In one embodiment, an energy storage system is also provided, which includes the secondary battery as above, and the specific structure of the secondary battery refers to the above embodiment. Since the energy storage system adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here one by one.

[0104] In one embodiment, an electrical device is also provided, including an energy storage system. The specific structure of the energy storage system refers to the above embodiment. Since the electrical device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0105] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0106] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A secondary battery cell tab tear detection method, characterized in that: Applicable to a secondary battery cell tab tear detection device, the secondary battery cell tab tear detection device is contact-connected with a secondary battery cell to be detected, the secondary battery cell to be detected is fixed with a tab, the secondary battery cell to be detected comprises a positive electrode and a negative electrode, and a double-layer capacitor is formed between the positive electrode and the negative electrode in an infiltrated electrolyte; the method comprises: After the secondary battery cell to be tested is fully immersed in the electrolyte, a first current test signal is applied to the secondary battery cell to be tested within a first target frequency range, wherein the double-layer capacitor is in an open circuit state within the first target frequency range; Testing the test resistance value of the secondary battery cell to be tested according to the first current test signal; An actual resistance value obtained by calibrating the test resistance value during the actual test process is determined, and based on the magnitude relationship between the actual resistance value and the preset resistance value, a tab tearing detection is performed on the secondary battery cell to be detected.

2. The method according to claim 1, characterized in that The actual test process includes a first test phase and a second test phase, the first test phase and the second test phase use first current test signals of different frequencies for testing, and the test resistance value includes a first test resistance value measured in the first test phase and a second test resistance value measured in the second test phase; The determining of the actual resistance value of the test resistance value obtained by calibration during the actual test process includes: Detecting a first polarization resistance value of the secondary cell to be detected according to the first test resistance value and the ohmic resistance value of the secondary cell to be detected, and detecting a second polarization resistance value of the secondary cell to be detected according to the second test resistance value and the ohmic resistance value; According to the first polarization resistance value and the second polarization resistance value, calibrating the polarization resistance of the secondary battery cell to be tested during the actual test process to obtain a target polarization resistance value of the secondary battery cell to be tested; The sum of the ohmic resistance value and the target polarization resistance value is taken as the actual resistance value.

3. The method according to claim 1, characterized in that The preset resistance value includes a first preset resistance value and a second preset resistance value, the first preset resistance value is smaller than the second preset resistance value, and the first preset resistance value is The second preset resistance is , and Respectively meet: , ; The step of performing a tab tear detection on the secondary battery cell to be detected according to the magnitude relationship between the actual resistance value and the preset resistance value comprises: After the secondary battery cell to be tested is formed, a second current test signal is applied to the secondary battery cell to be tested within a second target frequency interval, wherein the double-layer capacitor is in a short-circuit state within the second target frequency interval, and the first target frequency interval is , the second target frequency interval is ; Detecting the charge and discharge resistance value of the secondary battery cell to be detected according to the second current test signal; Determining a resistance difference between the actual resistance value and the charge and discharge resistance value; If the resistance difference is less than the preset resistance difference threshold, then when it is detected that the actual resistance value is greater than the first preset resistance value, it is determined that the tab of the secondary battery cell to be detected is torn, or when it is detected that the actual resistance value is less than or equal to the first preset resistance value, it is determined that the tab of the secondary battery cell to be detected is not torn; If the resistance difference is greater than or equal to the preset resistance difference threshold, then when it is detected that the actual resistance value is greater than the second preset resistance value, it is determined that the tab of the secondary battery cell to be tested has been torn, or when it is detected that the actual resistance value is less than or equal to the second preset resistance value, it is determined that the tab of the secondary battery cell to be tested does not have been torn.

4. The method according to claim 1, characterized in that: The applying a first current test signal to the secondary battery cell to be tested within the first target frequency range includes: Before the secondary battery cell to be detected is formed, detecting an initial voltage value of the secondary battery cell to be detected when immersed in the electrolyte; After determining that the secondary battery cell to be detected is qualified based on the initial voltage value, the first current test signal is applied to the secondary battery cell to be detected within a first target frequency range.

5. The method according to claim 1, characterized in that After performing the tab tearing detection on the secondary battery cell to be detected according to the magnitude relationship between the actual resistance value and the preset resistance value, the method further includes: After the to-be-detected secondary battery cell has tab tearing, detecting the total amount of tab-torn batteries in the battery module to which the to-be-detected secondary battery cell belongs; If the total amount of the torn tab cells is less than a preset total cell threshold, selecting an undetected secondary cell in the battery module as the secondary cell to be detected according to the cell identification information in the battery module; If the total amount of the tab-torn battery cells is greater than or equal to a preset total amount threshold of the battery cells, an abnormal prompt message is output, wherein the abnormal prompt message is used to prompt that the batch of battery cells in the battery module have tab torn.

6. A secondary battery cell tab tear detection device, characterized in that: The secondary battery cell tab tear detection device comprises a resistance measuring device and a host computer, wherein the resistance measuring device is contact-connected to the secondary battery cell to be detected, the resistance measuring device is communicatively connected to the host computer, the host computer comprises an application module and a detection module, the secondary battery cell to be detected is fixed with a tab, the secondary battery cell to be detected comprises a positive electrode and a negative electrode, and a double-layer capacitor is formed between the positive electrode and the negative electrode in the infiltrated electrolyte; wherein, The applying module is used to apply a first current test signal to the secondary battery cell to be detected within a first target frequency range after the secondary battery cell to be detected is fully immersed in the electrolyte, wherein the double-layer capacitor is in an open circuit state within the first target frequency range; The resistance measuring device is used to test the test resistance value of the secondary battery cell to be tested according to the first current test signal; The detection module is used to determine the actual resistance value of the test resistance value calibrated during the actual test process, and perform a tab tear detection on the secondary battery cell to be detected based on the size relationship between the actual resistance value and the preset resistance value.

7. The device according to claim 6, characterized in that The secondary battery cell tab tear detection device also includes a charge and discharge power supply module, which is contact-connected to the secondary battery cell to be detected, and is used to detect the charge and discharge resistance value of the secondary battery cell to be detected based on a second current test signal applied by the host computer to the secondary battery cell to be detected within a second target frequency range.

8. The device according to claim 6, characterized in that The secondary battery cell tab tear detection device also includes a voltage measuring device, which is contact-connected to the secondary battery cell to be detected, and is used to detect the initial voltage value of the secondary battery cell to be detected when it is immersed in the electrolyte before the secondary battery cell to be detected is formed.

9. The device according to claim 8, characterized in that The resistance measuring device is provided with a resistance test probe, the voltage measuring device is provided with a voltage test probe, the resistance test probe and the voltage test probe are isolated by an insulator, the secondary battery cell tab tear detection device also includes a motion component, the motion component includes a driving component, a guide component, a first positioning component and a supporting component, the battery module to which the secondary battery cell to be detected belongs is loaded on a loading platform, the supporting component supports the loading platform, and a second positioning component is provided on the loading platform, After the loading platform is located at the target position, the driving component drives the first positioning component and the second positioning component to perform positioning cooperation under the action of the guiding component, and after the positioning cooperation is completed, the resistance test probe contacts the first position of the positive pole and the second position of the negative pole respectively, and the voltage test probe contacts the third position of the positive pole and the fourth position of the negative pole respectively, wherein the first position, the second position, the third position and the fourth position are different from each other.

10. The device according to claim 6, characterized in that The secondary battery cell tab tear detection device also includes an information collector and a relay conversion board, and the information collector and the relay conversion board are respectively connected to the host computer for communication; wherein, The information collector is used to collect the cell identification information in the battery module to which the secondary cell to be tested belongs, and send the cell identification information to the host computer. The relay conversion board is used to convert the current test channel from the first target secondary cell to the second target secondary cell identified by the cell identification information according to the conversion instruction issued by the host computer, wherein the first target secondary cell and the second target secondary cell are different secondary cells in the battery module.

11. A secondary battery, characterized in that: The secondary battery comprises a secondary battery cell, and the secondary battery cell has no tab tearing, wherein the detection result of the secondary battery cell having no tab tearing is obtained by detection using the method according to any one of claims 1 to 5.

12. An energy storage system, characterized in that: The energy storage system comprises a plurality of secondary batteries as claimed in claim 11.

13. An electrical equipment, characterized in that: The electrical equipment includes the energy storage system as claimed in claim 12.

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