Method, device, battery, system and equipment for detecting tearing of secondary battery tab

Abstract

The present application relates to a method, device, battery, system and equipment for detecting the tearing of the tab of a secondary battery cell. It is applied to a device for detecting the tearing of the tab of a secondary battery cell that is in contact connection with the secondary battery cell to be detected. The secondary battery cell to be detected is fixed with tabs, and a double-layer capacitance is formed between the positive electrode and the negative electrode of the secondary battery cell to be detected in the infiltrated electrolyte. The method includes: after the secondary battery cell to be detected is fully infiltrated in the electrolyte, applying a first current test signal to the secondary battery cell to be detected in a first target frequency range, and the double-layer capacitance is in an open-circuit state in the first target frequency range; according to the first current test signal, testing the test resistance value of the secondary battery cell to be detected; and performing tab tearing detection on the secondary battery cell to be detected according to the magnitude relationship between the actual resistance value calibrated during the actual test process based on the test resistance value and a preset resistance value. Using this method improves the detection accuracy of detecting the tab tearing of the secondary battery cell.

Description

Technical Field

[0001] The present application relates to the technical field of cell performance testing, and particularly to a method and device for detecting the tearing of tabs of secondary cells, 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, tab tearing may occur during the welding process due to reasons such as folding, wrinkling, and misalignment in the multiple layers of current collectors. Tab tearing can further lead to problems such as burrs, abnormal protrusions, and fractures during subsequent assembly processes, thereby affecting the resistance value of the secondary cell. Therefore, it is very necessary to detect tab tearing in secondary cells.

[0003] Currently, during the detection of tab tearing in secondary cells, 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 tab 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 tab tearing detection for secondary cells has a problem of low accuracy. Summary of the Invention

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

[0005] In a first aspect, the present application provides a method for detecting the tearing of tabs of secondary cells, which is applied to a device for detecting the tearing of tabs of secondary cells. The device for detecting the tearing of tabs of secondary cells 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 capacitance 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 capacitance 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] Determine the actual resistance value calibrated during the actual test of the test resistance value, and perform ear tearing detection on the secondary cell to be detected according to the magnitude relationship between the actual resistance value and the preset resistance value.

[0009] In a second aspect, the present application further provides a secondary cell ear tearing detection device. The secondary cell ear tearing detection device includes a resistance measurement device and a host computer. The resistance measurement device is in contact connection with the secondary cell to be detected, and the resistance measurement device is communicatively connected to the host computer. The host computer includes an application module and a detection module. The secondary cell to be detected is fixed with ears. The secondary cell to be detected includes 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 application module is configured to apply a first current test signal to the secondary cell to be detected in a first target frequency range after the secondary cell to be detected is fully infiltrated in the electrolyte, wherein the double-layer capacitor is in an open circuit state in the first target frequency range;

[0011] The resistance measurement device is configured to test the test resistance value of the secondary cell to be detected according to the first current test signal;

[0012] The detection module is configured to determine the actual resistance value calibrated during the actual test of the test resistance value, and perform ear tearing detection on the secondary cell to be detected according to the magnitude relationship between the actual resistance value and the preset resistance value.

[0013] In a third aspect, the present application further provides a secondary battery. The secondary battery includes a secondary cell without ear tearing, wherein the detection result of the secondary cell without ear tearing is obtained by using the above secondary cell ear tearing detection method.

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

[0015] In a fifth aspect, the present application further provides an electrical device. The electrical device includes the above energy storage system.

[0016] The above secondary battery cell tab tearing detection method, device, secondary battery, energy storage system and electrical equipment. From the perspective of the deployment of the secondary battery cell tab tearing detection device, the secondary battery cell tab tearing detection device is in contact connection with the secondary battery cell to be detected. The secondary battery cell to be detected is provided with a positive electrode and a negative electrode. 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. After the secondary battery cell to be detected is fully infiltrated 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 performance of the secondary battery cell. When the secondary battery cell tab device applies a first current test signal to the secondary battery cell to be detected in the first target frequency range, the double-layer capacitor will be in an open circuit state, resulting in the impedance part of the double-layer capacitor in the circuit not being ignored. Thus, the change in the resistance 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 measured. Finally, based on the magnitude relationship between the actual resistance value calibrated in the actual test process and the preset resistance value through the test resistance value, the tab tearing detection of the secondary battery cell to be detected is performed. Since the actual resistance value calibrated by the secondary battery cell tab tearing detection device conforms to the actual test process and can measure the change in the resistance of the secondary battery cell under the polarization effect, the actual resistance value can reflect the actual impedance of the secondary battery cell in a specific state. Finally, using the detected actual resistance value as the detection basis for the tab tearing detection of the secondary battery cell to be detected is reliable. Therefore, in the case of the complex internal resistance components of the secondary battery cell static in the electrolyte and the total impedance detection of the DCIR device being completed using the charge and discharge characteristics of the secondary battery cell, and the polarization effect in the secondary battery cell changing with the charge and discharge process, etc., using 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 in a specific state. Therefore, the detection accuracy of the tab tearing detection of the secondary battery cell is improved. Description of the Drawings

[0017] To more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments or related technologies. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a flowchart of the secondary battery cell tab tearing detection method in an embodiment;

[0019] Figure 2 It is the first schematic diagram of a partial process in the battery preparation process of the secondary battery cell tab tearing detection method in an 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 chart 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 objectives, 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 of all, 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 may have welding tear phenomena caused by folding, wrinkling, misalignment and other defects due to the welding stress during the ultrasonic welding process. As a result, burrs, abnormal protrusions and fractures are likely to occur during the subsequent assembly process, 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 the contact resistance of other parts. At present, when detecting the welding tear phenomenon of a lithium-ion battery, 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 can be understood that the internal resistance value 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. Generally, the ACIR tester measures the impedance of the secondary battery cell by using a test frequency of 1 kHz and an amplitude of 5 mV. However, since the composition of the internal resistance value of the secondary battery cell statically placed in the electrolyte is complex, and both the DCIR device and the ACIR tester complete the total impedance detection by utilizing the characteristics of the secondary battery cell, and the polarization effect in the secondary battery cell changes with the charging and discharging process, the total impedance measured by the DCIR 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 obviously cannot include the polarization resistance formed by the electrochemical reaction of the secondary battery cell, resulting in the measured internal resistance value of the secondary battery cell being smaller than the actual resistance value. Furthermore, when the ear tearing detection of the secondary battery cell depends on the internal resistance value of the secondary battery cell, the situation will occur that the secondary battery cell with an ear tearing phenomenon is misdetected as a good product. Therefore, there is an urgent need for a method for detecting ear tearing of secondary battery cells that can improve the detection accuracy of ear tearing of secondary battery cells.

[0029] In one embodiment, as Figure 1 shown, a method for detecting ear tearing of secondary battery cells is provided. In this embodiment, taking the application of this method to a device for detecting ear tearing of secondary battery cells as an example, the device for detecting ear tearing of secondary battery cells is in contact connection with the secondary battery cell to be detected. The contact connection method can specifically be that the device for detecting ear tearing of secondary battery cells establishes an electrical connection with the secondary battery cell to be detected through test probes or test clips, etc. The device for detecting ear tearing of secondary battery cells includes a resistance measuring device and a host computer. Among them, the resistance measuring device is communicatively connected to the host computer. The resistance measuring device is used to measure the test resistance value of the battery cell to be detected according to the first current test signal applied by the host computer. The host computer includes, but is not limited to, a laptop computer, a smart phone, a tablet computer, etc. The host computer includes an application module and a detection module. 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. The detection module is used to determine the actual resistance value calibrated during the actual test of the test resistance value, and perform ear 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.

[0030] In the process of detecting the ear tearing of a secondary battery cell, certain detection conditions need to be met among the ear, the secondary battery cell to be detected, the resistance measuring device, and the host computer. First, the ear needs to 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 ear can be welded to the positive and negative electrodes of the secondary battery cell to be detected to achieve a reliable connection between the battery cell to be detected and the external circuit. The secondary battery cell to be detected is immersed in the 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. Among them, 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, due to the interaction between the electrode surface and the electrolyte, a dense charge layer will be formed on the electrode surface. This charge layer is composed of the charges on the electrode surface and the counter ions in the electrolyte, and they are closely arranged through the action of Coulomb force, thus forming the double-layer capacitor. At the same time, it is necessary to ensure that the secondary battery cell to be detected is fully immersed in the electrolyte to allow the secondary battery cell to be detected to undergo sufficient electrochemical reactions in the electrolyte, so that the polarization resistance value formed through the electrochemical reaction can accurately reflect the polarization impedance of the secondary battery cell to be detected. Then, the host computer controls the resistance measuring device to apply a first current test signal to the secondary battery cell to be detected within a first target frequency range. Among them, the double-layer capacitor is in an open circuit state within the first target frequency range. Then, the secondary battery cell ear tearing detection device measures the test resistance value of the secondary battery cell to be detected based on the first current test signal, so that the measured test resistance value is composed of two parts: the ohmic resistance value and the polarization resistance value, which can fit the actual application scenario. Then, the host computer determines the actual resistance value calibrated during the actual test of the test resistance value, and based on the magnitude relationship between the actual resistance value and the preset resistance value, the ear tearing detection of the secondary battery cell to be detected is carried out.

[0031] On the one hand, since the secondary battery cell ear tearing 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 in a specific state. On the other hand, since the actual resistance value is calibrated from the test resistance value to fit the actual test process, the actual resistance value can objectively reflect the actual impedance of the secondary battery cell to be detected in a specific state. Finally, using the detected actual resistance value as the detection basis for the ear tearing detection of the secondary battery cell to be detected is reliable. Therefore, the detection accuracy of the ear tearing 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 cell to be detected is fully infiltrated with the electrolyte, apply a first current test signal to the secondary 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 cell to be detected are fixed with electrode tabs. The electrode tab tearing detection for the secondary cell to be detected can specifically be the tearing detection for the first electrode tab fixed to the positive electrode of the secondary cell to be detected, the tearing detection for the second electrode tab fixed to the negative electrode of the secondary 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 cell to be detected refers to the secondary cell waiting for electrode tab tearing detection. The positive electrode and the negative electrode of the secondary cell to be detected can be either a single-layer conductive sheet or a multi-layer current collector formed by multi-layer conductive sheets. The conductive material thereof can specifically be aluminum or copper, etc. The electrolyte infiltrating the secondary 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 thereto. For example, in an implementable manner, both the positive electrode and the negative electrode of the secondary 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 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, refer to Figure 2 , Figure 2It is the first schematic diagram of a local process in the battery manufacturing process. First, a secondary cell is injected, followed by high-temperature infiltration and formation processes. After the formation process is completed, electrolyte wiping and high-temperature aging are carried out in sequence. Further, the secondary cell is transferred to the second injection, sealing nail welding, helium leak detection, formation, the first normal temperature standing, the first open circuit voltage (Open Circuit Voltage, OCV) measurement, the second normal temperature standing, the second open circuit voltage measurement, state of charge (State of Charge, SOC) adjustment, and the third normal temperature standing. Then, after the third normal temperature standing is completed, a DC internal resistance test process is set up, that is, the internal resistance value of the secondary cell is measured by a DC internal resistance test device. It can be understood that the secondary cell in the DC resistance test stage can be called the secondary cell to be detected. After the internal resistance value of the secondary cell to be detected is obtained through detection, subsequent processes such as the fourth normal temperature standing, the third open circuit voltage measurement, wrapping with blue film, appearance inspection, sorting, and warehousing are carried out. Thus, in the DC resistance test stage, after the internal resistance value of the secondary cell to be detected is obtained through detection by the DCIR device, the internal resistance value of the secondary cell to be detected can be used as the detection basis to detect the ear tearing situation of the secondary cell to be detected manually or automatically. In the AC resistance test stage, a sinusoidal waveform excitation current can be applied to the secondary cell to be detected, and then the internal resistance value of the secondary cell to be detected is calculated based on the phase difference and amplitude of the measured current and voltage, and the internal resistance value of the secondary cell to be detected is used as the detection basis to detect the ear tearing situation of the secondary cell to be detected.

[0035] It can be understood that there are obvious defects in the traditional technology in the process of detecting the ear tearing of the secondary cell to be detected. The DCIR device or ACIR tester uses the charge and discharge characteristics of the secondary cell to complete the total impedance detection, and can only detect the ohmic resistance value of the secondary cell to be detected. However, the internal resistance value components of the secondary cell to be detected immersed in the electrolyte are 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 cell to be detected will change with the charge and discharge process of the DCIR device or ACIR tester when measuring the impedance of the secondary cell, the polarization resistance value of the secondary cell to be detected cannot be accurately captured, resulting in the total impedance measured by the DCIR device or ACIR tester not being able to reflect the actual resistance value of the secondary cell in a specific state. Finally, it is unreliable to use the resistance value measured by the DCIR device or ACIR tester as the detection basis for ear tearing detection. Therefore, this embodiment provides another overall detection method for detecting the ear tearing of the secondary cell to be detected.

[0036] It should be noted that the secondary cell to be detected being fully immersed in the electrolyte is a prerequisite for the ear tearing detection of the secondary cell to be detected, which can ensure that the electrochemical reactions of the positive and negative electrodes of the secondary cell to be detected are complete in the immersed electrolyte. Specifically, the local processes in the traditional battery manufacturing process can be followed. For example, after the secondary cell completes the third normal temperature standing process, it can be considered that the secondary cell is fully immersed in the electrolyte. Or the local processes in the traditional battery manufacturing process can be improved. For example, when the secondary cell is undergoing the third normal temperature standing process, if the standing time reaches the preset time length, it is determined that the secondary cell is 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 normal temperature standing in the traditional process.

[0037] It should be noted that the secondary cell to be detected can be in contact connection with the internal resistance measuring device of the secondary cell ear tearing detection device. After the secondary cell to be detected is fully immersed in the electrolyte, the upper computer can trigger the internal resistance measuring device to apply a first current test signal to the secondary cell to be detected within the first target frequency range through the application module. Among them, the first current test signal is used to test the test resistance value of the secondary cell to be detected. The first target frequency range is the frequency range that makes the double-layer capacitance in an open circuit state. The internal resistance measuring device can specifically be a traditional ACIR tester, that is, an alternating current internal resistance tester. It can be understood that due to the impedance characteristics of the double-layer capacitance changing with frequency, the double-layer capacitance will show different states under current test signals in different frequency ranges. Specifically, under high-frequency current test signals, the capacitive reactance of the double-layer capacitance will be significantly reduced. After the capacitive reactance is reduced to a certain extent, the double-layer capacitance will be in a short circuit state. And under low-frequency current test signals, the capacitive reactance of the double-layer capacitance is relatively large. After the capacitive reactance is increased to a certain extent, the double-layer capacitance will be in an open circuit state.

[0038] Refer to Figure 3 , Figure 3 is a schematic diagram of the test circuit of the secondary cell to be detected when the double-layer capacitance is in different states. Among them, (a) is a schematic diagram of the first test circuit of the secondary cell to be detected when the double-layer capacitance 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 detected when the double-layer capacitance 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, It is the ohmic resistance component in the second test circuit. It can be understood that in the first test circuit, due to the high frequency of the first current test signal, the double-layer capacitor C1 is in a short-circuit state. Therefore, the measurement of the polarization resistance component will be ignored at this time, and the total internal resistance value detected by the secondary battery tab tear detection device is , in the second test circuit, due to the low frequency of the first current test signal, the double-layer capacitor C2 is in an open-circuit state. Therefore, the measurement of the polarization resistance component will be synchronously performed at this time, and the total internal resistance value detected by the secondary battery tab tear detection device is , for example, in an implementable manner, a traditional AC internal resistance tester applies a sine-wave current test signal of 1 KHz to the secondary battery to be detected to measure the impedance condition of the secondary battery to be detected. At this time, since the frequency of the sine-wave current test signal is relatively large and not within the first target frequency range, the internal test circuit of the secondary battery to be detected can refer to Figure 3 as shown in (a) therein, resulting in the failure to detect the polarization resistance value generated by the secondary battery to be detected under the polarization effect, ultimately affecting the detection accuracy of the tab tear detection of the secondary battery. However, for the secondary battery tab tear detection device provided in this embodiment, by applying a sine-wave current test signal of 1 Hz to the secondary battery to be detected, since the frequency of the sine-wave current test signal is relatively small and within the first target frequency range, the internal test circuit of the secondary battery to be detected can refer to Figure 3 as shown in (b) therein, resulting in the ability to detect the polarization resistance value generated by the secondary battery to be detected under the polarization effect, ultimately making the total resistance value relied on for the tab tear detection of the secondary battery reliable.

[0039] As an example, step 202 includes: after the host computer determines that the charge adjustment of the secondary battery to be detected is completed, if it detects that the static duration of the secondary battery to be detected at the first preset temperature is greater than the preset static duration, the host computer selects a first target frequency within the first target frequency range and controls the AC internal resistance tester to apply a first current test signal with the first target frequency to the secondary battery to be detected.

[0040] In an implementable manner, referring to Figure 4 , Figure 4 is the second schematic diagram of a local process in the battery manufacturing process. Among them, the DC internal resistance test process is replaced by the secondary battery tab tear detection process, that is, the secondary battery tab tear detection device provided in this embodiment is used to replace the traditional DC internal resistance test device to detect the total impedance condition of the secondary battery to be detected. For other processes in this local process, reference can be made to the above explanation Figure 2The relevant content at that time will not be elaborated here. Furthermore, after the secondary cell tab tearing detection device detects the tab tearing of the secondary cell, since the secondary cell tab tearing detection device can provide conditions for accurately detecting the total impedance of the secondary cell to be detected, it can lay a foundation for improving the detection accuracy of tab tearing detection of the secondary cell.

[0041] It can be understood that due to the complex preparation process flow of secondary cells and the large amount of manpower and material resources consumed in the process, if the tab tearing situation of secondary cells can be detected early, effective anti-fooling in the battery preparation process can be achieved, thereby reducing the preparation cost as much as possible. For example, the test devices on the existing production line usually have many processes such as high-temperature infiltration, formation, and standing between the formation process and the tab welding process after the capacitance grading process. And during the processes of formation, capacitance grading, and standing, there is no obvious change in the total impedance of the secondary cell to be detected. Furthermore, during the synchronous optimization of the production line test process, for example, in an implementable manner, refer to Figure 5 , Figure 5 is the third schematic diagram of the local process in the battery preparation process. Among them, a secondary cell tab tearing detection process is set after high-temperature infiltration, that is, the total impedance of the secondary cell to be detected is measured by setting a secondary cell tab tearing detection device, and the DC internal resistance test process originally located after the third normal temperature standing is cancelled, so as to advance the detection process of secondary cell tab tearing. Among them, after the high-temperature infiltration process is completed, a standing time still needs to be set to ensure that the secondary cell to be detected is fully infiltrated in the electrolyte.

[0042] As another example, step 202 includes: after the host computer determines that the secondary cell to be detected has completed infiltration at the second preset temperature, if it detects that the standing time of the secondary cell to be detected at the third preset temperature is greater than the preset standing time, the host computer selects a first target frequency within the first target frequency range and controls the resistance measurement device to apply a first current test signal with the first target frequency to the secondary cell to be detected, where the first preset temperature and the second preset temperature can both 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, according to the first current test signal, test the test resistance value of the secondary cell to be detected.

[0044] It should be noted that when measuring the resistance of the secondary cell to be detected by the resistance measuring device, a first current test signal can be applied to the cell to be detected, and the test resistance value of the secondary cell to be detected can be measured in real time. It can be understood that the traditional DCIR device needs to be equipped with a charge-discharge power supply module. For example, an independent power supply module is configured for each secondary cell channel, so as to measure the current and voltage of the secondary cell to be detected. Finally, the ratio of the voltage drop and current before and after the calculation is used as the resistance value of the secondary cell to be detected. In this embodiment, the test probe of the internal resistance measuring device can be in contact connection with the cell to be detected to directly measure the resistance value. When using an ACIR tester, there is no need to configure a charge-discharge power supply module. There are certain differences in the test methods between the two. It can be understood that the principle of the resistance measuring device for measuring the test resistance value of the secondary cell to be detected can refer to the specific algorithm in the traditional technology, which will not be elaborated in this embodiment.

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

[0046] In step 206, determine the actual resistance value calibrated during the actual test of the test resistance value, and perform an ear tear detection on the secondary cell to be detected according to the magnitude relationship between the actual resistance value and the preset resistance value.

[0047] It should be noted that due to the influence of objective environment and other factors, the measured test resistance values may be different. Therefore, by performing a test resistance value calibration process, the stability of the impedance situation of the secondary cell to be detected can be ensured. After obtaining the actual resistance value, the ear tear detection of the secondary cell to be detected can be completed based on the magnitude relationship between the actual resistance value and the preset resistance value. For example, in an implementable manner, 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 cell to be detected has an ear tear. When the actual resistance value is less than or equal to the preset resistance value, it is determined that the secondary cell to be detected has no ear tear.

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

[0049] It can be understood that the factors causing poor self-discharge are not only torn tabs, but also other adverse factors, such as pole piece burrs, internal metal foreign objects, internal micro-shorts, etc.; therefore, to determine whether the secondary cell to be detected has a torn tab, 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 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 of the test resistance value includes:

[0052] Step 302: Detect the 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 detect the 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 during the calibration of the test resistance value, the impedance of the double-layer capacitor has the characteristic of changing with frequency. Therefore, different first current test signals input in different test stages during the actual test process will also result in different impedance conditions of the secondary cell to be detected measured by the resistance measurement device. Furthermore, to avoid the frequency characteristic impedance error carried by the test resistance values obtained at different target frequencies within the first target frequency range, multiple test stages can be set during the actual test process. Among them, different first current test signals are used for testing in different test stages, so as to be able to detect the polarization impedance conditions of the secondary cell to be detected under the first current test signals of different frequencies, thus laying a foundation for calibrating the actual resistance value of the secondary cell to be detected subsequently. Among them, 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 upper computer in advance, and can be specifically obtained by testing with a traditional internal resistance measurement device. For example, in an implementable manner, during the actual test process of testing the test resistance value of the secondary cell to be detected according to the first current test signal, it can be divided into a first test stage and a second test stage. Among them, 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 as to be able to detect the polarization resistance values of the secondary cell to be detected measured under the first current test signals of different frequencies through the first test resistance value and the second test resistance value obtained in different test stages.

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

[0056] Step 304: Calibrate the polarization resistance of the secondary cell to be detected during the actual test process according to the first polarization resistance value and the second polarization resistance value to obtain the target polarization resistance value of the secondary cell to be detected.

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

[0058] As an example, step 304 includes: averaging the first polarization resistance value and the second polarization resistance value to obtain the target polarization resistance value calibrated for the secondary cell to be detected during actual testing.

[0059] As another example, step 304 includes: determining the first weight corresponding to the first polarization resistance value and the second weight corresponding to the second polarization resistance value, and obtaining the target polarization resistance value calibrated for the secondary cell to be detected during actual testing 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 the actual resistance value.

[0062] In this embodiment, during the actual testing of the secondary cell to be detected, the actual testing process is divided into a first testing stage and a second testing stage, and different first current test signals are used to test the secondary cell to be detected in different testing stages, obtaining the first test resistance value and the second test resistance value of the secondary cell to be detected. Then, the first polarization resistance value and the second polarization resistance value measured by the first current test signals of the secondary cell to be detected at different frequencies are obtained by using the first test resistance value and the second test resistance value. Thus, the target polarization resistance value of the secondary cell to be detected is calibrated through the first polarization resistance value and the second polarization resistance value, and finally the actual resistance value is solved, so as to objectively characterize the polarization resistance situation measured by the first current test signal applied within the first target frequency range by the target polarization resistance value, for subsequent obtaining an accurate actual resistance value. Therefore, it lays a foundation for further improving the detection accuracy of ear tearing detection for secondary cells.

[0063] In an implementable manner, 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 , and the second preset resistance value is , and respectively satisfy: , ; According to the magnitude relationship between the actual resistance value and the preset resistance value, perform tab tab tear detection on the secondary cell to be detected, including:

[0064] After the secondary cell to be detected is formed, apply a second current test signal to the secondary cell to be detected within the second target frequency range. Among them, the double-layer capacitor is in a short-circuit state within the second target frequency range, and the first target frequency range is , and the second target frequency range is ; According to the second current test signal, detect the charge and discharge resistance value of the secondary cell to be detected; determine the 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 secondary 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 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 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 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 tear situation of the secondary cell to be detected, the AC internal resistance tester of the secondary cell tab tear device can be applied to different processes in the measurement process of the actual resistance value. Among them, the charge and discharge resistance value measured by the AC internal resistance tester before the secondary cell to be detected is formed is used to verify the stability of the internal resistance characteristics of the secondary cell to be detected during the actual test process. Among them, the charge and discharge resistance value refers to the quantization value of the current blocking effect of the secondary cell to be detected under specific charge and discharge conditions. The specific charge and discharge conditions can specifically be specific charging conditions or specific discharge conditions, etc. Thus, the actual resistance value detected by the secondary cell tab tear device and preset resistance values of different magnitudes can be jointly used as the detection basis for the tab tear detection of the secondary cell. For example, in an implementable manner, assuming that the difference between the actual resistance value and the charge and discharge resistance value is small, it indicates that the internal resistance characteristics of the actual resistance value are stable during the actual test process. Then, a smaller first preset resistance value is set as the determination criterion for the tab tear situation during the actual test process. Assuming that the difference between the actual resistance value and the charge and discharge resistance value is large, it indicates that there may be an abnormal internal resistance situation for the actual resistance value during the actual test process. At this time, a larger second preset resistance value is set as the determination criterion for the tab tear situation, so as to ensure the accurate classification of whether the secondary cell has a tab tear.

[0066] It should be noted that the preset resistance values include a first preset resistance value and a second preset resistance value. The first preset resistance value is less than the second preset resistance value. The first preset resistance value is any resistance value greater than 0.17 and less than 0.19 The second preset resistance value is any resistance value greater than 0.19 and less than 0.25 The second target frequency range refers to the frequency range in which the electric double layer capacitor is in a short - circuit state. Specifically, the first target frequency range is and the second target frequency range is That is, the first target frequency selected within the first target frequency range is any frequency not less than 0.1 Hz and not greater than 10 Hz, and the second target frequency selected within the second target frequency range is any frequency greater than 10 Hz and not greater than 1050 Hz. In an implementable manner, referring to Figure 7 Figure 7 is the fourth schematic diagram of a local process in the battery preparation process. Among them, after high - temperature infiltration, a secondary cell tab tearing detection process is set. In the secondary cell tab tearing detection process, a secondary cell tab tearing detection device uses a first current test signal of 1 Hz to measure the total impedance of the secondary cell to be detected. After the third room - temperature standing, a direct - current internal resistance test process is set. The direct - current internal resistance test process uses a second current test signal of 1 kHz by a direct - current internal resistance test device to measure the total impedance of the secondary cell to be detected. It can be understood that the direct - current internal resistance test process can also be set at any process position from after formation to before warehousing.

[0067] As an example, after the charge adjustment of the secondary cell to be detected, if the standing time of the secondary cell to be detected at the fourth preset temperature is greater than the preset standing time, then a second target frequency is selected within the second target frequency range, and an alternating - current internal resistance tester is controlled to apply a second current test signal to the secondary cell to be detected. Among them, the electric double layer capacitor is in a short - circuit state within the second target frequency range. The first target frequency range is and the second target frequency range is ​, the fourth preset temperature can specifically be 25°C; receive the charge-discharge resistance value of the secondary cell to be detected based on the feedback of the second current test signal; subtract the actual resistance value from the charge-discharge resistance value to obtain a resistance difference value; if the resistance difference value is less than the preset resistance difference threshold value, then when it is detected that the actual resistance value is greater than the first preset resistance value, it is determined that the secondary cell to be detected has a torn tab, 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 cell to be detected does not have a torn tab; if the resistance difference value is greater than or equal to the preset resistance difference threshold value, then when it is detected that the actual resistance value is greater than the second preset resistance value, it is determined that the secondary cell to be detected has a torn tab, 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 cell to be detected does not have a torn tab.

[0068] In this embodiment, by setting the AC internal resistance tester to test and obtain the charge-discharge resistance value before the formation of the secondary cell to be detected, and then using the charge-discharge resistance value to assist in the detection process of the torn tab of the secondary cell with the actual resistance value as the detection basis, so as to ensure that different preset resistance values can be set for the actual resistance value as the comparison object in different situations, and finally accurately detect whether the secondary cell to be detected has a torn tab according to the size relationship between the actual resistance value and the preset resistance value. Therefore, it further lays a foundation for improving the detection accuracy of the torn tab of the secondary cell.

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

[0070] Before the formation of the secondary cell to be detected, detect the initial voltage value of the secondary cell to be detected when it is immersed in the electrolyte; after determining that the secondary cell to be detected is qualified based on the initial voltage value, apply a first current test signal to the secondary cell to be detected within the first target frequency range.

[0071] It should be noted that a voltage measuring device can also be set in the secondary cell torn tab detection device to detect the initial voltage value of the electrolyte before formation to prevent the quality risk of the secondary cell to be detected. For example, in an implementable manner, the voltage measuring device can specifically be a voltmeter. By setting a voltmeter before formation, the initial voltage value of the secondary cell to be detected when it is immersed in the electrolyte is detected. Only when the voltage of the secondary cell to be detected 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 cell to be detected, without performing the torn tab detection on the secondary cell to be detected with unqualified quality, reducing the workload of the torn tab detection of the secondary cell.

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

[0073] In this embodiment, by deploying a voltage measuring device in the secondary cell tab tearing device, the initial voltage value of the secondary cell to be detected soaked in the electrolyte is detected, and according to the magnitude relationship between the initial voltage value and the preset voltage threshold, after it is determined that the secondary cell to be detected is qualified, a first current test signal is applied to the secondary cell to be detected within the first target frequency range, thereby avoiding the situation of performing invalid tab tearing detection on the secondary cell to be detected. Therefore, while laying a foundation for improving the detection accuracy of tab tearing detection of secondary cells, the detection flexibility of tab tearing detection of secondary cells is synchronously improved.

[0074] In one embodiment, after performing 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 secondary cell to be detected has a tab tear, the total number of tab torn cells in the battery module to which the secondary cell to be detected belongs is detected; if the total number of tab torn cells is less than the preset total cell threshold, an undetected secondary cell is selected as the secondary cell to be detected in the battery module according to the cell identification information in the battery module; if the total number of tab torn cells is greater than or equal to the preset total cell threshold, an abnormal prompt message is output, where the abnormal prompt message is used to prompt that there is a tab tear in the batch of cells in the battery module.

[0076] It should be noted that in the actual application scenario, usually, tab tearing detection is performed on multiple secondary cells of a certain module. After detecting the tab tearing situation of the current secondary cell to be detected, the object of tab tearing detection can be replaced. Then, after completing the tab tearing situation detection of all secondary cells in the entire battery module, the total number of tab torn cells with tab tears is counted, and the quality of the battery preparation process is controlled with the total number of tab torn cells as an index. Among them, the abnormal prompt message is used to prompt that there is a tab tear in the batch of cells in the battery module, which can specifically be a sound prompt message or a text prompt message, etc. For example, in an implementable manner, the host computer monitors the test process of the battery module in real time and classifies and counts the defective products of the secondary cells. If secondary cells with internal resistance defects continuously appear during the test, the host computer controls the secondary cell tab tearing detection device to trigger an abnormal alarm to prompt an abnormal tab batch welding tear.

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

[0078] In this embodiment, by integrating the tab tear detection conditions of all secondary battery cells in the battery module to which the secondary battery cell to be detected belongs, the tab tear detection process of the secondary battery cells in the battery module is monitored in real time, and in the case of batch welding tear abnormalities, timely warnings are given through abnormal prompt messages, so that the purpose of effectively controlling the tab tear detection conditions of a batch of battery cells in the battery module can be achieved. Therefore, it lays a foundation for improving the detection effect of tab tear detection of secondary battery cells.

[0079] It should be understood that although the steps in the flowcharts involved in the above embodiments are shown in sequence according to the arrows, these steps do not necessarily have to be executed in the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps has no strict order limit, 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. These steps or stages do not necessarily have to be executed at the same time, but can be executed at different times. The execution order of these steps or stages does not necessarily have to be sequential, but can be executed alternately or in turn with at least a part of other steps or 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 above-mentioned secondary battery cell tab tear detection method. The solution provided by this device to solve the problem is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the secondary battery cell tab tear detection device provided below can refer to the limitations on the secondary battery cell tab tear detection method in the above text, and will not be repeated here.

[0081] In an exemplary embodiment, a secondary battery tab tearing detection device is provided, including a resistance measurement device and a host computer. The resistance measurement device is in contact connection with the secondary battery to be detected, and the resistance measurement device is communicatively connected to the host computer. The host computer includes an application module and a detection module. The secondary battery to be detected is fixed with tabs. The secondary battery to be detected includes 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] The application module is configured to apply a first current test signal to the secondary battery to be detected in a first target frequency range after the secondary battery to be detected is fully infiltrated in the electrolyte, wherein the double-layer capacitor is in an open circuit state in the first target frequency range;

[0083] The resistance measurement device is configured to test the test resistance value of the secondary battery to be detected according to the first current test signal;

[0084] The detection module is configured to determine the actual resistance value calibrated during the actual test of the test resistance value, and perform tab tearing detection on the secondary battery to be detected according to the magnitude relationship between the actual resistance value and the preset resistance value.

[0085] In one of the embodiments, the secondary battery tab tearing detection device further includes a charge and discharge power supply module. The charge and discharge power supply module is in contact connection with the secondary battery to be detected. The charge and discharge power supply module is configured to detect the charge and discharge resistance value of the secondary battery to be detected according to a second current test signal applied by the host computer to the secondary battery to be detected in a second target frequency range.

[0086] It should be noted that by setting an AC internal resistance tester to test the charge and discharge resistance value before the formation of the secondary battery to be detected, and then using the charge and discharge resistance value to assist in using the actual resistance value as the detection basis for the secondary battery tab tearing detection process, a charge and discharge power supply module can also be deployed in the secondary battery tab tearing detection device. The charge and discharge power supply module can be in contact connection with the secondary battery to be detected through test probes, etc. The charge and discharge power supply module is configured to detect the charge and discharge resistance value of the secondary battery to be detected according to a second current test signal applied by the host computer to the secondary battery to be detected in a second target frequency range.

[0087] In one of the embodiments, the secondary battery tab tearing detection device further includes a voltage measurement device. The voltage measurement device is in contact connection with the secondary battery to be detected. The voltage measurement device is configured to detect the initial voltage value of the secondary battery to be detected when it is infiltrated in the electrolyte before the formation of the secondary battery to be detected.

[0088] It should be noted that to prevent the quality risks of the secondary battery cells to be detected, 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 detected when immersed in the electrolyte before formation. Specifically, the voltage measuring device can be a voltmeter, and the voltage measuring device is in contact connection with the secondary battery cells to be detected through test probes.

[0089] In one embodiment, the resistance measuring device is provided with resistance test probes, and the voltage measuring device is provided with voltage test probes. The resistance test probes and the voltage test probes are isolated by an insulator. The secondary battery cell tab tearing detection device further includes a motion assembly. The motion assembly includes a driving component, a guiding component, a first positioning component, and a supporting component. The battery module to which the secondary battery cells to be detected belong is loaded on a loading platform. The supporting component supports the loading platform. A second positioning component is provided on the loading platform. After the loading platform is in 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 probes respectively contact the first position of the positive electrode and the second position of the negative electrode, and the voltage test probes respectively contact the third position of the positive electrode and the fourth position of the negative electrode, where the first position, the second position, the third position, and the fourth position are pairwise different.

[0090] It should be noted that the resistance test probes and the voltage test probes are isolated by an insulator to prevent short - circuit phenomena. Specifically, the insulator can be polytetrafluoroethylene or silica gel. To facilitate the user to view the panel data on the secondary battery cell tab tearing detection device, a four - wire connection method can be used for the connection between the secondary battery cells to be detected and the resistance measuring device and the voltage measuring device respectively. Among them, the resistance measuring device is an impedance tester, and the voltage measuring device is a voltmeter. The voltmeter and the impedance tester are respectively fixed in 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 assembly to meet the motion requirements of the secondary battery cell tab tearing detection device during actual testing.

[0091] In an implementable manner, the driving component can specifically be a cylinder, the guiding component can specifically be a guide pillar, the first positioning component can specifically be a positioning pin, the supporting component can specifically be a supporting rod, the carrying platform is a tray, the battery module to which the secondary battery cell to be detected belongs is loaded in the tray, the tray is supported by the supporting rod, a positioning hole (second positioning component) is provided on the tray, and under the control of the host computer, the moving component drives the tray to move to the target position, and the target position can specifically be the test starting position specified by the user. After reaching the target position, the cylinders on the left and right sides will drive the positioning pin and the positioning hole to cooperate with each other under the action of the guide pillar to complete positioning in the horizontal direction. Among them, the resistance measuring device is in contact connection with the secondary battery cell to be detected carried on the tray through a resistance test probe, the voltage measuring device is in contact connection with the secondary battery cell to be detected carried on the tray through a voltage test probe, and both the voltage test probe and the resistance test probe are fixed on the fixing plate and contact the positive and negative electrode posts of the secondary battery cell to be detected at different positions to form a four-wire connection method, so as to realize the acquisition 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 in pairs.

[0092] It can be understood that through the secondary battery cell tab tearing detection device with automated movement, by adopting the method of using a carrying platform to carry the battery module to which the secondary battery cell to be detected belongs, after the carrying platform moves into place, the secondary battery cell tab tearing detection device can continuously and continuously perform tab tearing detection on the secondary battery cells in the battery module without the need for the mechanism to move during the test, avoiding the influence on the accuracy during movement.

[0093] In an embodiment, the secondary battery cell tab tearing detection device further includes an information collector and a relay conversion board, and the information collector and the relay conversion board are respectively communicatively connected to the host computer; among them, 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 switch 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, where the first target secondary battery cell and the second target secondary battery cell are different secondary battery cells in the battery module.

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

[0095] Thus, compared with the traditional DCIR device that uses a moving mechanism to move the test probe, resulting in relatively low efficiency during mass production, in this embodiment, the number of secondary battery cells corresponds one-to-one with the number of test probes. There is no need to move the probes. Instead, the test channels are switched through an electronic relay conversion board. The switching process is faster and more efficient than the physical movement of the probes.

[0096] Referring to Figure 8 , Figure 8 is a schematic diagram of a partial module of the secondary battery cell tab tearing detection device. In the schematic diagram of the module, the secondary battery cell tab tearing detection device may specifically include a voltmeter 400, an AC impedance tester 401, a guide post 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. Among them, 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 by the secondary battery cell tab tearing detection device can not only perform tab tearing detection on any secondary battery cell in the battery module based on the actual resistance value as the detection basis, but also control the tab tearing situation and process of a batch of battery cells in the battery module. Therefore, through the secondary battery cell tab tearing detection device provided in this embodiment, not only can the detection accuracy of tab tearing detection for secondary battery cells be improved, but also the detection effect of tab tearing detection for secondary battery cells can be enhanced. At the same time, by setting different types of test probes and forming a four-wire test method to contact the positive and negative electrodes of the secondary battery cell to be detected respectively, the purpose of respectively collecting the initial voltage value and test resistance value of the secondary battery cell to be detected can be achieved. At the same time, by switching the current test channel through the electronic relay conversion board, the detection efficiency of the overall tab tearing situation of the battery module to which the secondary battery cell to be detected belongs can be effectively improved. Moreover, relying on the automatic conveyor line and the method of loading a full tray of secondary battery cells using a tray, after the secondary battery cell to be detected arrives, the secondary battery cell tab tearing detection device can continuously work to detect different secondary battery cells in the battery module, thereby avoiding excessive movement of the secondary battery cell tab tearing detection device during the detection process. Therefore, it can also overcome the influence of the movement of the secondary battery cell tab tearing detection device on the test resistance value test accuracy of the secondary battery cell to be detected, and further improve the detection accuracy of tab tearing detection for the secondary battery cell to be detected.

[0097] It can be understood that when different detection devices are used to detect secondary batteries with different capacities, the actual resistance values detected for different secondary batteries under different detection devices are different. As a result, there are differences in the detected tearing conditions of the secondary cell tabs based on the actual resistance values. 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 secondary cell tab tearing. 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. From the test data shown in Table 1 above, it can be seen that 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, using the resistance value measured by the AC resistance tester with a 1 Hz current test signal as the detection basis, the detection rate for 9120 secondary battery cells' tab tear conditions is 99.8%. Using the resistance value measured by the AC resistance tester with a 1 kHz current test signal as the detection basis, the detection rate is 98.50%. Using 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 cell, since the impedance test of the secondary battery cell using a 1 Hz current test signal can more truly reflect the actual impedance of the secondary battery cell compared to the impedance test of the secondary battery cell 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 cell using a 1 Hz current test signal can also more truly reflect the actual impedance of the secondary battery cell compared to the impedance test of the secondary battery cell using the DC internal resistance test device, which also improves the accuracy of the overall secondary battery cell tab tear detection of the battery module to a certain extent. 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 cell 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 a 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 without ear tearing. The detection result of the ear tearing of the secondary battery cell without ear tearing is obtained by the above-mentioned method for detecting ear tearing of the secondary battery cell.

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

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

[0105] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered as the scope described in this specification.

[0106] The above embodiments only represent several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A method for detecting the tearing of the tab of a secondary battery cell, characterized in that, Applied to a secondary battery cell tab tearing detection device, the secondary battery cell tab tearing detection device is in contact connection with a secondary battery cell to be detected. The secondary battery cell to be detected is fixed with tabs. The secondary battery cell to be detected includes 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. The method includes: After the secondary battery cell to be detected is fully infiltrated in the electrolyte, a first current test signal is applied to the secondary battery cell to be detected in a first target frequency range, wherein the double-layer capacitor is in an open circuit state in the first target frequency range; According to the first current test signal, the test resistance value of the secondary battery cell to be detected is measured; Determine the actual resistance value calibrated during the actual test of the test resistance value, and perform 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 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 a first test resistance value measured in the first test stage and a second test resistance value measured in the second test stage. Determining the actual resistance value calibrated during the actual test of the test resistance value includes: Detect a first polarization resistance value of the secondary battery cell to be detected according to the first test resistance value and the ohmic resistance value of the secondary battery cell to be detected, and detect a second polarization resistance value of the secondary battery cell to be detected according to the second test resistance value and the ohmic resistance value. Calibrate the polarization resistance of the secondary battery cell to be detected during the actual test according to the first polarization resistance value and the second polarization resistance value to obtain the target polarization resistance value of the secondary battery cell to be detected. Take the sum value of the ohmic resistance value and the target polarization resistance value as the actual resistance value.

2. The method according to claim 1, wherein The preset resistance values include 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 , and the second preset resistance value is . And respectively satisfy: , ; The method for performing tab tear detection on the secondary cell to be detected according to the magnitude relationship between the actual resistance value and the preset resistance value includes: After the formation of the secondary cell to be detected, a second current test signal is applied to the secondary cell to be detected in a second target frequency range, wherein the double-layer capacitor is in a short-circuit state in the second target frequency range, and the first target frequency range is , and the second target frequency range is ; According to the second current test signal, detect the charge-discharge resistance value of the secondary battery cell to be detected; Determine the resistance difference between the actual resistance value and the charge-discharge resistance value; If the resistance difference is less than the preset resistance difference threshold, 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, 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.

3. The method according to claim 1, wherein Applying the first current test signal to the secondary battery cell to be detected in the first target frequency range includes: Before the secondary battery cell to be detected is formed, detect the initial voltage value of the secondary battery cell to be detected infiltrated in the electrolyte; After determining that the secondary battery cell to be detected is qualified based on the initial voltage value, apply the first current test signal to the secondary battery cell to be detected within the first target frequency range.

4. The method according to claim 1, wherein After performing the 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, the method further includes: After a tab tear occurs in the secondary battery cell to be detected, detect the total number of tab-teared battery cells in the battery module to which the secondary battery cell to be detected belongs; If the total number of tab-teared battery cells is less than the preset total battery cell threshold, select an undetected secondary battery cell in the battery module as the secondary battery cell to be detected according to the cell identification information in the battery module; If the total number of tab-teared battery cells is greater than or equal to the preset total battery cell threshold, output an abnormal prompt message, where the abnormal prompt message is used to prompt that there is a tab tear in the batch of battery cells in the battery module.

5. A secondary cell tab tearing detection device, characterized in that, For implementing the secondary battery cell tab tear detection method according to any one of claims 1 to 4, the secondary battery cell tab tear detection device includes a resistance measurement device and a host computer. The resistance measurement device is in contact connection with the secondary battery cell to be detected, and the resistance measurement device is communicatively connected to the host computer. The host computer includes an application module and a detection module. The secondary battery cell to be detected is fixed with tabs. The secondary battery 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; wherein, The application module is configured to apply a first current test signal to the secondary battery cell to be detected within the first target frequency range after the secondary battery cell to be detected is fully infiltrated in the electrolyte, wherein the double-layer capacitor is in an open circuit state within the first target frequency range; The resistance measurement device is configured to test the test resistance value of the secondary battery cell to be detected according to the first current test signal; The detection module is configured to determine the actual resistance value calibrated during the actual test of the test resistance value, and perform 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.

6. The device according to claim 5, wherein The secondary battery cell tab tear detection device further includes a charge and discharge power supply module. The charge and discharge power supply module is in contact connection with the secondary battery cell to be detected. The charge and discharge power supply module is configured to detect the charge and discharge resistance value of the secondary battery cell to be detected according to a second current test signal applied by the host computer to the secondary battery cell to be detected within a second target frequency range.

7. The device according to claim 5, characterized in that The secondary battery cell tab tear detection device further includes a voltage measurement device. The voltage measurement device is in contact connection with the secondary battery cell to be detected. The voltage measurement device is configured to detect the initial voltage value of the secondary battery cell to be detected when it is infiltrated in the electrolyte before formation.

8. The device according to claim 7, characterized in that, The resistance measurement device is provided with a resistance test probe, the voltage measurement device is provided with a voltage test probe, and the resistance test probe and the voltage test probe are isolated by an insulator. The secondary battery cell tab tearing detection device further includes a motion assembly, and the motion assembly includes a driving component, a guiding 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 arranged on the loading platform. After the loading platform is in 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. After the positioning cooperation is completed, the resistance test probe respectively contacts the first position of the positive electrode and the second position of the negative electrode, and the voltage test probe respectively contacts the third position of the positive electrode and the fourth position of the negative electrode. Among them, the first position, the second position, the third position, and the fourth position are different from each other in pairs.

9. The device according to claim 5, characterized in that, The secondary battery cell tab tearing detection device further includes an information collector and a relay conversion board, and the information collector and the relay conversion board are respectively communicatively connected to the host computer; among them, 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. The relay conversion board is used to switch the current test channel from a first target secondary battery cell to a second target secondary battery cell identified by the cell identification information according to the conversion instruction issued by the host computer. Among them, the first target secondary battery cell and the second target secondary battery cell are different secondary battery cells in the battery module.

10. A secondary battery, characterized in that, The secondary battery includes a secondary battery cell without tab tearing, and the detection result of the secondary battery cell without tab tearing is obtained by using the method according to any one of claims 1 to 4.

11. An energy storage system, characterized in that, The energy storage system includes a plurality of secondary batteries according to claim 10.

12. An electrical device, characterized in that, The electrical equipment includes an energy storage system according to claim 11.

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