Battery tab welding quality detection method and device and storage medium

Abstract

The invention discloses a battery tab welding quality detection method and device and a storage medium, and belongs to the technical field of battery detection. The method comprises the following steps: acquiring the tab connection internal resistance of a welded to-be-detected battery; under the condition that the tab connection internal resistance is smaller than or equal to a first internal resistance threshold value, charging and discharging the to-be-tested battery to obtain tab temperature data of the to-be-tested battery; based on the tab temperature data, determining a first temperature rise rate of the to-be-tested battery; the first temperature rise rate is compared with a target temperature rise rate, the welding quality detection result of the battery to be detected is determined according to the comparison result, and the target temperature rise rate is the temperature rise rate of charging and discharging of the battery with the qualified tab welding quality. According to the method, the welding quality of the tab of the to-be-detected battery is judged by monitoring the temperature rise rate of the tab of the to-be-detected battery after welding is completed, the pseudo soldering condition can be rapidly and accurately detected, and the battery structure is not damaged.

Description

Technical Field

[0001] The present application belongs to the field of battery detection technology, and in particular, relates to a battery tab welding quality detection method, device and storage medium. Background Art

[0002] After lithium-ion batteries come off the production line, the finished product performance test needs to weld the tabs and connect the charging and discharging equipment to conduct the electrical performance, life performance, thermal performance and safety performance evaluation. If the welding is cold, it will cause the consistency of the electrical performance and power performance evaluation to be abnormal, and an alarm may occur during the cycle life test, resulting in the inability to carry out the cycle test normally.

[0003] At present, battery cold soldering is mainly detected through resistance measurement, voltage change, internal resistance change, and whether it is easy to damage manually. These methods have certain limitations and cannot detect battery cold soldering quickly and accurately, and may also cause damage to the battery structure. Summary of the invention

[0004] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a battery tab welding quality detection method, device and storage medium, which can quickly and accurately detect the cold welding situation without damaging the battery structure.

[0005] In a first aspect, the present application provides a method for detecting the welding quality of a battery tab, the method comprising:

[0006] Obtain the internal resistance of the tab connection of the battery to be tested after welding;

[0007] When the tab connection internal resistance is less than or equal to a first internal resistance threshold, charging and discharging the battery to be tested to obtain tab temperature data of the battery to be tested;

[0008] Determining a first temperature rise rate of the battery to be tested based on the tab temperature data;

[0009] The first temperature rise rate is compared with a target temperature rise rate, and a welding quality test result of the battery to be tested is determined according to the comparison result. The target temperature rise rate is the temperature rise rate of charging and discharging of a battery with qualified tab welding quality.

[0010] According to the battery tab welding quality detection method of the present application, by monitoring the temperature rise rate at the battery tab to be tested that has completed welding, the welding quality at the battery tab to be tested can be judged, and the cold welding situation can be detected quickly and accurately without damaging the battery structure.

[0011] According to one embodiment of the present application, the step of obtaining the tab temperature data of the battery to be tested includes:

[0012] Sampling is performed at a sampling time interval to obtain the tab temperature data of the battery to be tested at multiple sampling moments;

[0013] The determining, based on the tab temperature data, a first temperature rise rate of the battery to be tested, comprises:

[0014] The first temperature rise rate corresponding to each sampling moment is determined based on the tab temperature data corresponding to each sampling moment.

[0015] According to one embodiment of the present application, the first temperature rise rate is determined by the following steps:

[0016] Determine the change in the lug temperature at the current sampling moment based on the lug temperature data at the current sampling moment and the lug temperature data at the previous sampling moment;

[0017] The first temperature rise rate at the current sampling moment is determined based on the test duration corresponding to the current sampling moment and the tab temperature change.

[0018] According to an embodiment of the present application, comparing the first temperature rise rate with the target temperature rise rate, and determining the welding quality test result of the battery to be tested according to the comparison result, includes:

[0019] The first temperature rise rate corresponding to the sampling moment is compared with the target temperature rise rate, and the welding quality detection result of the battery to be tested is determined according to the comparison result.

[0020] According to one embodiment of the present application, charging and discharging the battery to be tested includes:

[0021] Discharging the battery under test at a constant current to a discharge cut-off voltage, and leaving it to rest for a first target time;

[0022] According to the constant current charging mode or the step charging mode, the battery to be tested is charged to the charging cut-off voltage.

[0023] According to one embodiment of the present application, charging the battery to be tested according to the constant current charging mode, comparing the first temperature rise rate with the target temperature rise rate, and determining the welding quality detection result of the battery to be tested according to the comparison result, includes:

[0024] In a first timing period, when the first temperature rise rate corresponding to a sampling moment is greater than the target temperature rise rate, it is determined that the tab of the battery to be tested is poorly soldered, and the start time of the first timing period is the start time of charging the battery to be tested.

[0025] According to an embodiment of the present application, charging the battery to be tested according to the step charging mode, comparing the first temperature rise rate with the target temperature rise rate, and determining the welding quality detection result of the battery to be tested according to the comparison result, includes:

[0026] In the second timing period, when the first temperature rise rate at the corresponding sampling moment is greater than the target temperature rise rate, it is determined that the tab of the battery to be tested is poorly welded, and the starting time of the second timing period is the moment when the current of the battery to be tested is greater than or equal to the first current threshold.

[0027] According to one embodiment of the present application, after obtaining the tab connection internal resistance of the battery to be tested after welding, the method further includes:

[0028] When the tab connection internal resistance is greater than the first internal resistance threshold, it is determined that the tab of the battery to be tested is poorly soldered.

[0029] In a second aspect, the present application provides a battery tab welding quality detection device, the device comprising:

[0030] The first processing module is used to obtain the internal resistance of the tab connection of the battery to be tested after welding;

[0031] A second processing module is used to charge and discharge the battery to be tested and obtain the tab temperature data of the battery to be tested when the tab connection internal resistance is less than or equal to a first internal resistance threshold;

[0032] A third processing module, used for determining a first temperature rise rate of the battery to be tested based on the tab temperature data;

[0033] The fourth processing module is used to compare the first temperature rise rate with the target temperature rise rate, and determine the welding quality test result of the battery to be tested according to the comparison result, wherein the target temperature rise rate is the temperature rise rate of charging and discharging of a battery with qualified tab welding quality.

[0034] According to the battery tab welding quality detection device of the present application, by monitoring the temperature rise rate at the battery tab to be tested that has completed welding, the welding quality at the battery tab to be tested can be judged, and the cold welding situation can be detected quickly and accurately without damaging the battery structure.

[0035] In a third aspect, the present application provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the method for detecting the welding quality of the battery tab as described in the first aspect above is implemented.

[0036] In a fourth aspect, the present application provides a non-transitory computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the battery tab welding quality detection method as described in the first aspect above is implemented.

[0037] In a fifth aspect, the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the battery tab welding quality detection method as described in the first aspect above.

[0038] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0040] Figure 1 It is one of the flow charts of the battery tab welding quality detection method provided in the embodiment of the present application;

[0041] Figure 2 This is the second flow chart of the battery tab welding quality detection method provided in the embodiment of the present application;

[0042] Figure 3 It is a structural schematic diagram of a battery tab welding quality detection device provided in an embodiment of the present application;

[0043] Figure 4 This is a schematic diagram of a time-voltage curve of Comparative Example 1 provided in an embodiment of the present application;

[0044] Figure 5 It is a schematic diagram of the time-temperature curve of Comparative Example 1 provided in the embodiments of the present application;

[0045] Figure 6 1 is a schematic diagram of a time temperature rise rate curve of Comparative Example 1 provided in an embodiment of the present application;

[0046] Figure 7 This is a schematic diagram of a time-voltage curve of Example 1 provided in the embodiments of the present application;

[0047] Figure 8 This is a schematic diagram of the time-temperature curve of Example 1 provided in the examples of the present application;

[0048] Fig. 9 This is a schematic diagram of the time temperature rise rate curve of Example 1 provided in the examples of the present application;

[0049] Fig.10 This is a schematic diagram of a time-voltage curve of Comparative Example 2 provided in an embodiment of the present application;

[0050] Fig.11 This is a schematic diagram of the time-temperature curve of Comparative Example 2 provided in the embodiments of the present application;

[0051] Fig.12 This is a schematic diagram of the time temperature rise rate curve of Comparative Example 2 provided in the embodiments of the present application;

[0052] Fig.13 This is a schematic diagram of a time-voltage curve of Example 2 provided in the embodiments of the present application;

[0053] Fig.14 This is a schematic diagram of the time-temperature curve of Example 2 provided in the examples of the present application;

[0054] Fig.15 This is a schematic diagram of the time temperature rise rate curve of Example 2 provided in the examples of the present application;

[0055] Fig.16 This is a schematic diagram of a time-voltage curve of Comparative Example 3 provided in an embodiment of the present application;

[0056] Fig.17 This is a schematic diagram of the time-temperature curve of Comparative Example 3 provided in the embodiments of the present application;

[0057] Fig.18 This is a schematic diagram of the time temperature rise rate curve of Comparative Example 3 provided in the embodiments of the present application;

[0058] Fig.19 This is a schematic diagram of a time-voltage curve of Example 3 provided in the embodiments of the present application;

[0059] Fig. 20 This is a schematic diagram of the time-temperature curve of Example 3 provided in the examples of the present application;

[0060] Fig.21 This is a schematic diagram of the time temperature rise rate curve of Example 3 provided in the examples of the present application;

[0061] Fig. 22 Schematic diagram of time-current curves of Comparative Example 4 and Example 4 provided in the embodiments of the present application;

[0062] Fig.23 This is a schematic diagram of a time-voltage curve of Comparative Example 4 provided in an embodiment of the present application;

[0063] Fig.24 This is a schematic diagram of the time-temperature curve of Comparative Example 4 provided in the embodiments of the present application;

[0064] Fig.25 Schematic diagram of the time temperature rise rate curve of Comparative Example 4 provided in the embodiment of the present application;

[0065] Fig.26 This is a schematic diagram of a time-voltage curve of Example 4 provided in the embodiments of the present application;

[0066] Fig. 27 This is a schematic diagram of the time-temperature curve of Example 4 provided in the examples of the present application;

[0067] Fig.28 This is a schematic diagram of the time temperature rise rate curve of Example 4 provided in the examples of the present application;

[0068] Fig.29 It is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0069] The following will be combined with the drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application belong to the scope of protection of this application.

[0070] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0071] In the following, in conjunction with the accompanying drawings, the battery tab welding quality detection method, battery tab welding quality detection device, electronic device and readable storage medium provided in the embodiments of the present application are described in detail through specific embodiments and their application scenarios.

[0072] Among them, the battery tab welding quality detection method can be applied to the terminal, and can be specifically executed by hardware or software in the terminal.

[0073] The battery tab welding quality detection method provided in the embodiment of the present application can be executed by an electronic device or a functional module or functional entity in the electronic device that can implement the battery tab welding quality detection method.

[0074] like Figure 1 As shown, the battery tab welding quality detection method includes: step 110, step 120, step 130 and step 140.

[0075] Step 110, obtaining the tab connection internal resistance of the battery to be tested after welding.

[0076] It can be understood that the tab is a metal conductor that leads the positive and negative electrodes out of the battery, that is, the tab is the contact point for charging and discharging the battery.

[0077] Among them, the tab connection internal resistance refers to the contact internal resistance at the tab of the battery to be tested that has completed welding.

[0078] In this step, under certain welding parameters, the tabs are welded onto the battery to be tested. After welding, the battery to be tested is connected to a charging and discharging device to test the tab connection internal resistance of the battery to be tested.

[0079] It should be noted that when a cold solder joint occurs, the contact internal resistance between the tab and the battery increases (i.e., the tab connection internal resistance increases), which will cause abnormalities in the consistency of the electrical performance and power performance evaluation of the battery to be tested.

[0080] Step 120: When the tab connection internal resistance is less than or equal to the first internal resistance threshold, the battery to be tested is charged and discharged to obtain tab temperature data of the battery to be tested.

[0081] The first internal resistance threshold is a preset contact internal resistance critical value.

[0082] In this embodiment, by comparing the tab connection internal resistance of the battery to be tested with the first internal resistance threshold, it is determined whether the contact internal resistance between the tab of the battery to be tested and the battery exceeds the normal range, and a preliminary judgment is made based on the contact internal resistance whether a cold solder joint occurs in the battery to be tested.

[0083] In this step, when the tab connection internal resistance is less than or equal to the first internal resistance threshold, it indicates that the contact internal resistance between the tab of the battery to be tested and the battery does not exceed the normal range. The battery to be tested is charged and discharged, and the tab temperature data of the battery to be tested is obtained. The tab temperature data is used to accurately determine whether the battery to be tested has a cold solder joint.

[0084] In this embodiment, the tab temperature data refers to the temperature data at the tab of the battery to be tested collected when the battery to be tested is charged and discharged.

[0085] Step 130: Determine a first temperature rise rate of the battery to be tested based on the tab temperature data.

[0086] It can be understood that the temperature rise rate is the speed at which the temperature of an object rises, and represents the change of the object's temperature over time.

[0087] In this step, according to the tab temperature data of the battery to be tested, the ratio of the temperature change to the time change when the temperature at the tab of the battery to be tested rises is calculated to obtain the first temperature rise rate of the battery to be tested.

[0088] Step 140: compare the first temperature rise rate with the target temperature rise rate, and determine the welding quality test result of the battery to be tested according to the comparison result.

[0089] Among them, the target temperature rise rate is the temperature rise rate of charging and discharging of batteries with qualified tab welding quality.

[0090] It should be noted that cold soldering will cause the contact resistance at the pole ear to increase. During the charging and discharging process, more heat will be generated when the current passes through the cold soldering point, and the heat generated by the cold soldering point cannot be effectively dissipated. The temperature of the pole ear near the cold soldering point will rise rapidly, and the temperature rise rate of the cold soldering is higher than the temperature rise rate of the normally welded pole ear. The cold soldering pole ear reaches a higher temperature peak in a short time, which is higher than the temperature peak of the normally welded pole ear.

[0091] In this step, the first temperature rise rate of the battery to be tested is compared with the target temperature rise rate. When the first temperature rise rate of the battery to be tested is higher than the target temperature rise rate, it indicates that the battery to be tested may have a cold weld. When the first temperature rise rate of the battery to be tested is lower than or equal to the target temperature rise rate, it indicates that the welding quality of the battery tab to be tested is qualified.

[0092] In actual implementation, the temperature rise rate at the battery tab can be obtained by performing charge and discharge tests on a battery with qualified tab welding quality, and the target temperature rise rate can be obtained. The target temperature rise rate can be the maximum temperature rise rate at the battery tab.

[0093] For example, battery A with qualified welding quality of the tab is charged and discharged, and three tests are performed to obtain three groups of temperature rise rates of battery A, and the group of temperature rise rates with the largest value among the three groups of temperature rise rates is taken as the target temperature rise rate.

[0094] In this embodiment, by comparing the maximum temperature rise rate (i.e., the target temperature rise rate) of a battery with qualified tab welding quality with the first temperature rise rate of the battery to be tested, the misjudgment rate of poor solder joints in the battery to be tested can be effectively reduced, and the accuracy of the welding quality detection results of the battery to be tested can be improved.

[0095] It can be understood that the battery with qualified tab welding quality used to measure the target temperature rise rate is consistent with the type and specification of the battery to be tested, the welding is completed using the same welding parameters, the charging and discharging conditions for obtaining the temperature rise rate are also the same, and the temperature data collection location is also the same, which effectively ensures the accuracy of the welding quality detection of the battery to be tested.

[0096] In the related art, after the lithium-ion battery is welded, it is first inspected by metallographic examination, tensile test, appearance observation and other means, and then the contact internal resistance (1000Hz impedance value) of the lithium-ion battery is tested by an internal resistance meter to determine whether there is a cold solder joint. The resistance measurement method is prone to cold solder joints and missed inspections.

[0097] In the embodiment of the present application, by charging and discharging the battery to be tested that has completed welding, monitoring the temperature rise rate at the pole ear of the battery to be tested, and judging the welding quality at the pole ear of the battery to be tested, the battery cold welding situation can be detected quickly and accurately, and the problem that the resistance measurement method is prone to cold welding and missed detection can be solved. The battery welding quality can be more intuitively reflected through the temperature characteristics. The first temperature rise rate of the battery to be tested is directly compared with the target temperature rise rate of charging and discharging of the battery with qualified pole ear welding quality. No complex algorithm is required, the detection process is simpler, no high-rate discharge equipment is required, the detection process is safer, and there is no damage to the battery structure.

[0098] According to the battery tab welding quality detection method provided in the embodiment of the present application, by monitoring the temperature rise rate at the battery tab to be tested that has completed welding, the welding quality at the battery tab to be tested can be judged, and the cold welding situation can be detected quickly and accurately without damaging the battery structure.

[0099] In some embodiments, after obtaining the internal resistance of the tab connection of the battery to be tested after welding in step 110, the battery tab welding quality detection method may further include:

[0100] When the tab connection internal resistance is greater than the first internal resistance threshold, it is determined that the tab of the battery to be tested is poorly soldered.

[0101] In this embodiment, when the tab connection internal resistance is greater than the first internal resistance threshold, it indicates that the contact internal resistance between the tab of the battery to be tested and the battery has exceeded the normal range, and the internal resistance is used to determine whether a cold solder joint occurs at the tab of the battery to be tested.

[0102] In some embodiments, obtaining the tab temperature data of the battery to be tested may include:

[0103] Sampling is performed at a sampling time interval to obtain the lug temperature data of the battery to be tested at multiple sampling moments;

[0104] Based on the lug temperature data, determining a first temperature rise rate of the battery to be tested includes:

[0105] Based on the tab temperature data corresponding to each sampling moment, the first temperature rise rate corresponding to each sampling moment is determined.

[0106] In this embodiment, by presetting the sampling time interval, the temperature data at the tab of the battery to be tested is collected according to the sampling time interval, and the tab temperature data of the battery to be tested at multiple sampling moments during the charging and discharging process is obtained. Based on the tab temperature data at each sampling moment, the first temperature rise rate corresponding to each sampling moment can be calculated.

[0107] For example, the sampling time interval is 10s, and the battery to be tested is charged and discharged. The tab temperature data A is collected at 10s, the tab temperature data B is collected at 20s, and the tab temperature data C is collected at 30s.

[0108] The first temperature rise rate of the battery to be tested at the 10th second is calculated according to the tab temperature data A, the first temperature rise rate of the battery to be tested at the 20th second is calculated according to the tab temperature data B, and the first temperature rise rate of the battery to be tested at the 30th second is calculated according to the tab temperature data C.

[0109] In some embodiments, the first temperature rise rate is determined by the following steps:

[0110] Determine the change in the lug temperature at the current sampling moment based on the lug temperature data at the current sampling moment and the lug temperature data at the previous sampling moment;

[0111] Based on the test duration and the lug temperature change corresponding to the current sampling moment, the first temperature rise rate at the current sampling moment is determined.

[0112] The test duration corresponding to the current sampling moment is the duration from the previous sampling moment to the current sampling moment, that is, the sampling time interval.

[0113] In this embodiment, the difference between the tab temperature data of the battery to be tested at the current sampling moment and the previous sampling moment is obtained to obtain the tab temperature change at the current sampling moment, and the ratio of the tab temperature change to the sampling time interval is used as the first temperature rise rate at the current sampling moment.

[0114] For example, the current sampling time is the 60th second of the battery under test being charged and discharged. The lug temperature data at the 60th second is subtracted from the lug temperature data at the 0th second to obtain the lug temperature change at the 60th second. The ratio of the lug temperature change to 60 is the first temperature rise rate at the 60th second.

[0115] The lug temperature data at the 120th second is subtracted from the lug temperature data at the 60th second to obtain the lug temperature change at the 120th second. The ratio of the lug temperature change to 60 is the first temperature rise rate at the 120th second.

[0116] In some embodiments, comparing the first temperature rise rate with the target temperature rise rate, and determining the welding quality test result of the battery to be tested according to the comparison result, includes:

[0117] The first temperature rise rate corresponding to the sampling moment is compared with the target temperature rise rate, and the welding quality detection result of the battery to be tested is determined according to the comparison result.

[0118] It is understandable that when the battery is charging and discharging, the temperature changes differently at different times.

[0119] In this embodiment, when obtaining the target temperature rise rate of a battery with qualified tab welding quality, detection can be performed at the same sampling time interval as the battery to be tested to obtain the target temperature rise rate, and the first temperature rise rate at the corresponding sampling moment is compared with the target temperature rise rate to obtain the welding quality detection result of the battery to be tested.

[0120] For example, when the sampling time interval is 10s, a battery with qualified tab welding quality is charged and discharged, and the target temperature rise rate of the battery at 10s, 20s and 30s is calculated; the battery to be tested is charged and discharged, and the first temperature rise rate of the battery to be tested at 10s, 20s and 30s is calculated.

[0121] The first temperature rise rate at the 10th second is compared with the target temperature rise rate, the first temperature rise rate at the 20th second is compared with the target temperature rise rate, and the first temperature rise rate at the 30th second is compared with the target temperature rise rate to obtain the welding quality test result of the battery to be tested.

[0122] It can be understood that the smaller the sampling time interval, the higher the accuracy of the lug welding quality detection of the battery to be tested.

[0123] In actual implementation, the same sampling time interval is used to obtain the target temperature rise rate and the first temperature rise rate at multiple sampling moments, and the time temperature rise rate curves of the battery to be tested and the battery with qualified tab welding quality can be plotted. By comparing the two time temperature rise rate curves, when the time temperature rise rate curve of the battery to be tested exceeds the time temperature rise rate curve of the battery with qualified tab welding quality in the vertical coordinate (temperature rise rate), it can be determined that the battery to be tested has a cold weld.

[0124] A specific embodiment is described below.

[0125] like Figure 2 As shown, under certain welding parameters, the battery to be tested and the tab are welded.

[0126] The battery to be tested that has completed welding is connected to the charging and discharging equipment, and the test internal resistance is ≤0.05mΩ, that is, the internal resistance of the tab connection of the battery to be tested is less than or equal to the first internal resistance threshold of 0.05mΩ.

[0127] The battery under test is subjected to charge and discharge tests, and the lug temperature, voltage, current and other data are monitored. The charge and discharge process of the battery under test is monitored through the voltage, current and other data.

[0128] According to the lug temperature data, draw a temperature change curve over time, calculate the temperature rise rate, and draw a 30s-60s temperature rise rate over time curve. Compare the temperature rise rate over time curves of the battery to be tested and the battery with qualified welding quality to determine whether the battery to be tested has a cold solder joint.

[0129] In some embodiments, charging and discharging the battery to be tested may include:

[0130] Discharge the battery under test at a constant current to the discharge cut-off voltage, and leave it to rest for a first target time;

[0131] According to the constant current charging mode or the step charging mode, the battery to be tested is charged to the charging cut-off voltage.

[0132] In this embodiment, the battery to be tested is first discharged to a discharge cut-off voltage by constant current discharge, and then the battery to be tested is left to stand for a first target time to stabilize the state of the battery to be tested, and then the battery to be tested is charged by a constant current charging mode or a step charging mode to charge the battery to a charging cut-off voltage.

[0133] For example, the charging and discharging of the battery to be tested includes a discharge phase and a charge phase. The ambient temperature of the battery to be tested is adjusted to 25±2°C. In the discharge phase, the battery to be tested is discharged at a constant current of 1C-2C to a discharge cut-off voltage. The battery to be tested is then left to stand for 30 minutes. In the charging phase, the battery to be tested is charged to a charge cut-off voltage in a constant current charging mode of 1C-3C, or the battery to be tested is charged to a charge cut-off voltage in a step charging mode of different rates.

[0134] In actual implementation, the lug temperature data during the charging stage can be used to detect the lug welding quality of the battery to be tested, and the lug temperature, current, voltage and other data during the charging stage can be obtained. The lug temperature data is used to calculate the temperature rise rate to detect the welding quality of the battery to be tested, and the current, voltage and other data can be used to monitor the charging process of the battery to be tested.

[0135] It is understandable that under different charging modes, the temperature of the tab changes with time in different ways. For the constant current charging mode and the step charging mode, different judgment methods are used to determine the tab welding quality of the battery to be tested.

[0136] In some embodiments, charging the battery to be tested in a constant current charging mode, comparing the first temperature rise rate with the target temperature rise rate, and determining the welding quality test result of the battery to be tested according to the comparison result, including:

[0137] In the first timing period, when the first temperature rise rate corresponding to the sampling moment is greater than the target temperature rise rate, it is determined that the tab of the battery to be tested is poorly welded.

[0138] The start time of the first timing period is the start time of charging the battery to be tested.

[0139] In the constant current charging mode, starting from the charging start time of the battery to be tested, the first temperature rise rate corresponding to the sampling time in the first timing period is greater than the target temperature rise rate, indicating that the battery to be tested has a poorly soldered tab.

[0140] It can be understood that within the first timing period, the first temperature rise rate corresponding to the sampling moment is less than or equal to the target temperature rise rate, which can determine that the welding quality of the tab of the battery to be tested is qualified.

[0141] For example, in the constant current charging mode, the first 500 seconds after the start of charging has a first temperature rise rate greater than the target temperature rise rate, and it is determined that the tab of the battery to be tested is poorly soldered.

[0142] In some embodiments, charging the battery to be tested according to the step charging mode, comparing the first temperature rise rate with the target temperature rise rate, and determining the welding quality test result of the battery to be tested according to the comparison result, including:

[0143] In the second timing period, when the first temperature rise rate corresponding to the sampling moment is greater than the target temperature rise rate, it is determined that the tab of the battery to be tested is poorly welded.

[0144] The start time of the second timing period is the time when the current of the battery to be tested is greater than or equal to the first current threshold.

[0145] In the step charging mode, the current of the battery to be tested gradually increases, starting from the moment when the current of the battery to be tested is greater than or equal to the first current threshold. The first temperature rise rate corresponding to the sampling moment in the second timing period is greater than the target temperature rise rate, indicating that the battery to be tested has a poorly soldered tab.

[0146] It can be understood that, within the second timing period, the first temperature rise rate corresponding to the sampling moment is less than or equal to the target temperature rise rate, and it can be judged that the welding quality of the tab of the battery to be tested is qualified.

[0147] For example, in the step charging mode, if the current of the battery to be tested is equal to the first current threshold and the battery to be tested has a first temperature rise rate greater than the target temperature rise rate 500 seconds before the current is equal to the first current threshold, it is determined that the tab of the battery to be tested is poorly welded.

[0148] Several specific embodiments are described below.

[0149] Take the lithium iron phosphate (LiFePO4) battery system as an example, charging in a constant current charging mode at a 1C rate.

[0150] A 129Ah square shell battery with a pole ear welded was selected, and the battery to be tested after welding was completed was used as Example 1, and the battery with qualified pole ear welding quality was used as Comparative Example 1.

[0151] Example 1 is connected to the charging and discharging equipment to test the connection internal resistance between the pole ear and the charging and discharging power line (i.e., the pole ear connection internal resistance). After the connection internal resistance test passes, the pole ear temperature data is obtained.

[0152] The battery of Example 1 and Comparative Example 1 was charged and discharged, and the data such as the lug temperature, battery voltage, and battery current were monitored.

[0153] The charging and discharging conditions for Example 1 and Comparative Example 1 are as follows: the ambient temperature is 25±2°C; the battery is discharged at a constant current rate of 1C to 2.0V; the battery is allowed to stand for 30 minutes; the battery is charged at a constant current and constant voltage rate of 1C to 3.65V, with a cut-off current of 0.05C; and the battery is allowed to stand for 30 minutes.

[0154] Figure 4 The time voltage curve diagram of comparative example 1 is shown. Figure 5 Shown is a schematic diagram of the time-temperature curve of Comparative Example 1, Figure 6 Shown is a schematic diagram of the time temperature rise rate curve of Comparative Example 1.

[0155] Figure 7 The time voltage curve diagram of Example 1 is shown. Figure 8 The time-temperature curve diagram of Example 1 is shown. Fig. 9 Shown is a schematic diagram of the time temperature rise rate curve of Example 1.

[0156] By comparing the curves of voltage, temperature and temperature rise rate changing with time, it is found that the voltage change of Example 1 is not obvious compared with Comparative Example 1, the temperature change of the tab is large, and the difference in the change is obvious in the first 500s. The temperature rise rate of Example 1 in the first 500s is higher than that of Comparative Example 1 by about 0.1°C / 60s, and the highest reaches 0.8°C / 60s. It is judged that the battery to be tested in Example 1 has a cold solder joint, and the welding residual area of ​​Example 1 is about 50%.

[0157] Take the lithium iron phosphate (LiFePO4) battery system as an example, charging in a constant current charging mode at a 2C rate.

[0158] A 129Ah square shell battery with a pole ear welded was selected, and the battery to be tested after welding was completed was used as Example 2, and the battery with qualified pole ear welding quality was used as Comparative Example 2.

[0159] Example 2 is connected to the charging and discharging equipment to test the connection internal resistance between the pole ear and the charging and discharging power line (i.e., the pole ear connection internal resistance). After the connection internal resistance test passes, the pole ear temperature data is obtained.

[0160] Example 2 and Comparative Example 2 were charged and discharged, and data such as the tab temperature, battery voltage, and battery current were monitored.

[0161] The charging and discharging conditions for Example 2 and Comparative Example 2 are as follows: the ambient temperature is 25±2°C; the battery is discharged at a constant current rate of 1C to 2.0V; the battery is allowed to stand for 30 minutes; the battery is charged at a constant current and constant voltage rate of 2C to 3.65V, with a cut-off current of 0.05C; and the battery is allowed to stand for 30 minutes.

[0162] Fig.10 The time voltage curve schematic diagram of comparative example 2 is shown. Fig.11 Shown is a schematic diagram of the time-temperature curve of Comparative Example 2, Fig.12 Shown is a schematic diagram of the time temperature rise rate curve of Comparative Example 2.

[0163] Fig.13 The time voltage curve schematic diagram of Example 2 is shown. Fig.14 The time-temperature curve diagram of Example 2 is shown. Fig.15 Shown is a schematic diagram of the time temperature rise rate curve of Example 2.

[0164] By comparing the curves of voltage, temperature and temperature rise rate changing with time, it is found that the voltage change of Example 2 is not obvious compared with Comparative Example 2, the temperature change of the tab temperature is large, and the difference in change is obvious in the first 500s. The temperature rise rate of Example 2 in the first 500s is higher than that of Comparative Example 2 by about 0.3°C / 60s, and the highest reaches 9.4°C / 60s. It is judged that the battery to be tested in Example 2 has a cold solder joint, and the welding residual area of ​​Example 2 is about 60%.

[0165] Take the lithium iron phosphate (LiFePO4) battery system as an example, charging in a constant current charging mode at a 3C rate.

[0166] A 129Ah square shell battery with a pole ear welded was selected, and the battery to be tested after welding was completed was used as Example 3, and the battery with qualified pole ear welding quality was used as Comparative Example 3.

[0167] Example 3 is connected to the charging and discharging equipment to test the connection internal resistance between the pole ear and the charging and discharging power line (i.e., the pole ear connection internal resistance). After the connection internal resistance test passes, the pole ear temperature data is obtained.

[0168] Example 3 and Comparative Example 3 were charged and discharged, and data such as the tab temperature, battery voltage, and battery current were monitored.

[0169] The charging and discharging conditions for Example 3 and Comparative Example 3 are as follows: the ambient temperature is 25±2°C; the battery is discharged at a constant current rate of 1C to 2.0V; the battery is allowed to stand for 30 minutes; the battery is charged at a constant current and constant voltage rate of 2C to 3.65V, with a cut-off current of 0.05C; and the battery is allowed to stand for 30 minutes.

[0170] Fig.16 The time voltage curve diagram of comparative example 3 is shown. Fig.17 Shown is a schematic diagram of the time-temperature curve of Comparative Example 3, Fig.18 Shown is a schematic diagram of the time temperature rise rate curve of Comparative Example 3.

[0171] Fig.19 The time voltage curve schematic diagram of Example 3 is shown. Fig. 20The time-temperature curve diagram of Example 3 is shown. Fig.21 Shown is a schematic diagram of the time temperature rise rate curve of Example 3.

[0172] By comparing the curves of voltage, temperature and temperature rise rate changing with time, it is found that the voltage change of Example 3 is not obvious compared with Comparative Example 3, the temperature change of the tab is large, and the difference in change is obvious in the first 500s. The temperature rise rate of Example 3 in the first 500s is higher than that of Comparative Example 3 by about 1.6°C / 60s, and the highest reaches 15.3°C / 60s. It is judged that the battery to be tested in Example 3 has a cold solder joint, and the welding residual area of ​​Example 3 is about 40%.

[0173] It is understandable that as the current increases, the temperature rise rate increases. Detecting the lug temperature under high-rate charging conditions can effectively improve the detection rate of battery cold soldering.

[0174] Take the nickel (Ni), cobalt (Co) and manganese (Mn) ternary battery system and charging according to the step charge mode (SC) as an example.

[0175] A 147Ah square shell battery with a pole ear welded was selected, and the battery to be tested after welding was completed was used as Example 4, and the battery with qualified pole ear welding quality was used as Comparative Example 4.

[0176] Example 4 is connected to the charging and discharging equipment to test the connection internal resistance between the pole ear and the charging and discharging power line (i.e., the pole ear connection internal resistance). After the connection internal resistance test passes, the pole ear temperature data is obtained.

[0177] The Example 4 and the Comparative Example 4 were charged and discharged, and the data such as the tab temperature, the battery voltage, and the battery current were monitored.

[0178] The charging and discharging conditions for Example 4 and Comparative Example 4 are as follows: the ambient temperature is 25±2°C; the battery is discharged to 2.75V at a constant current of 1C rate; the battery is left standing for 30 minutes; the battery is charged to 4.3V in a step charging mode with a cutoff current of 0.05C; and the battery is left standing for 30 minutes.

[0179] Fig. 22 The time current curve diagram of Comparative Example 4 and Example 4 is shown as follows: Fig. 22 As shown, the step charging mode divides the charging process into multiple stages (ie steps), and the charging current in each stage can be different.

[0180] Fig.23 The time voltage curve diagram of comparative example 4 is shown. Fig.24 Shown is a schematic diagram of the time-temperature curve of Comparative Example 4, Fig.25 Shown is a schematic diagram of the time temperature rise rate curve of Comparative Example 4.

[0181] Fig.26The time voltage curve diagram of Example 4 is shown. Fig. 27 The time-temperature curve diagram of Example 4 is shown. Fig.28 Shown is a schematic diagram of the time temperature rise rate curve of Example 4.

[0182] When charging is performed in a step charging mode, an over-temperature protection threshold is set, and the voltage data after over-temperature is not collected in Comparative Example 4 and Example 4.

[0183] By comparing the curves of voltage, temperature and temperature rise rate changing with time, it is found that the voltage change of Example 4 is not obvious compared with Comparative Example 4, the temperature change of the tab temperature is large, and the change difference is obvious after 500s when the current changes to a large current greater than the first current threshold. The temperature rise rate of Example 4 is higher than that of Comparative Example 4 by about 4°C / 60s, and the highest reaches 14°C / 60s. It is judged that the battery to be tested in Example 4 has a cold solder joint, and the welding residual area of ​​Example 4 is about 70%.

[0184] The battery tab welding quality detection method provided in the embodiment of the present application can be executed by a battery tab welding quality detection device. In the embodiment of the present application, the battery tab welding quality detection method is executed by a battery tab welding quality detection device as an example to illustrate the battery tab welding quality detection device provided in the embodiment of the present application.

[0185] The embodiment of the present application also provides a battery tab welding quality detection device.

[0186] like Figure 3 As shown, the battery tab welding quality detection device comprises:

[0187] The first processing module 310 is used to obtain the internal resistance of the tab connection of the battery to be tested after welding;

[0188] The second processing module 320 is used to charge and discharge the battery to be tested and obtain the lug temperature data of the battery to be tested when the lug connection internal resistance is less than or equal to the first internal resistance threshold;

[0189] A third processing module 330 is used to determine a first temperature rise rate of the battery to be tested based on the tab temperature data;

[0190] The fourth processing module 340 is used to compare the first temperature rise rate with the target temperature rise rate, and determine the welding quality test result of the battery to be tested according to the comparison result. The target temperature rise rate is the temperature rise rate of charging and discharging of the battery with qualified tab welding quality.

[0191] According to the battery tab welding quality detection device provided in the embodiment of the present application, by monitoring the temperature rise rate at the battery tab to be tested that has completed welding, the welding quality at the battery tab to be tested is judged, and the cold welding situation can be detected quickly and accurately without damaging the battery structure.

[0192] In some embodiments, the second processing module 320 is used to obtain the tab temperature data of the battery to be tested, including:

[0193] Sampling is performed at a sampling time interval to obtain the lug temperature data of the battery to be tested at multiple sampling moments;

[0194] The third processing module 330 is used to determine a first temperature rise rate of the battery to be tested based on the tab temperature data, including:

[0195] Based on the tab temperature data corresponding to each sampling moment, the first temperature rise rate corresponding to each sampling moment is determined.

[0196] In some embodiments, the first temperature rise rate is determined by the following steps:

[0197] Determine the change in the lug temperature at the current sampling moment based on the lug temperature data at the current sampling moment and the lug temperature data at the previous sampling moment;

[0198] Based on the test duration and the lug temperature change corresponding to the current sampling moment, the first temperature rise rate at the current sampling moment is determined.

[0199] In some embodiments, the fourth processing module 340 is used to compare the first temperature rise rate with the target temperature rise rate, and determine the welding quality detection result of the battery to be tested according to the comparison result, including:

[0200] The first temperature rise rate corresponding to the sampling moment is compared with the target temperature rise rate, and the welding quality detection result of the battery to be tested is determined according to the comparison result.

[0201] In some embodiments, the second processing module 320 is used to charge and discharge the battery to be tested, including:

[0202] Discharge the battery under test at a constant current to the discharge cut-off voltage, and leave it to rest for a first target time;

[0203] According to the constant current charging mode or the step charging mode, the battery to be tested is charged to the charging cut-off voltage.

[0204] In some embodiments, the second processing module 320 is used to charge the battery to be tested in a constant current charging mode, and the fourth processing module 340 is used to compare the first temperature rise rate with the target temperature rise rate, and determine the welding quality detection result of the battery to be tested according to the comparison result, including:

[0205] In the first timing period, when the first temperature rise rate corresponding to the sampling time is greater than the target temperature rise rate, it is determined that the tab of the battery to be tested is poorly soldered, and the start time of the first timing period is the start time of charging the battery to be tested.

[0206] In some embodiments, the second processing module 320 is used to charge the battery to be tested according to the step charging mode, and the fourth processing module 340 is used to compare the first temperature rise rate with the target temperature rise rate, and determine the welding quality detection result of the battery to be tested according to the comparison result, including:

[0207] In the second timing period, when the first temperature rise rate corresponding to the sampling moment is greater than the target temperature rise rate, it is determined that the tab of the battery to be tested is poorly welded, and the start time of the second timing period is the moment when the current of the battery to be tested is greater than or equal to the first current threshold.

[0208] In some embodiments, after obtaining the tab connection internal resistance of the battery to be tested that has completed welding, the fourth processing module 340 is further used to determine that the tab of the battery to be tested is poorly welded when the tab connection internal resistance is greater than the first internal resistance threshold.

[0209] The battery tab welding quality detection device in the embodiment of the present application can be an electronic device, or a component in an electronic device, such as an integrated circuit or a chip.

[0210] The battery tab welding quality detection device provided in the embodiment of the present application can realize each process realized in the above-mentioned battery tab welding quality detection method embodiment, and will not be described again here to avoid repetition.

[0211] In some embodiments, Fig.29 As shown, an embodiment of the present application also provides an electronic device 2900, including a processor 2901, a memory 2902, and a computer program stored in the memory 2902 and executable on the processor 2901. When the program is executed by the processor 2901, each process of the above-mentioned battery tab welding quality detection method embodiment is implemented, and the same technical effect can be achieved. To avoid repetition, it will not be described here.

[0212] It should be noted that the electronic devices in the embodiments of the present application include the mobile electronic devices and non-mobile electronic devices mentioned above.

[0213] An embodiment of the present application also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the various processes of the above-mentioned battery tab welding quality detection method embodiment are implemented, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0214] The processor is the processor in the electronic device described in the above embodiment. The readable storage medium includes a computer readable storage medium, such as a computer read-only memory ROM, a random access memory RAM, a magnetic disk or an optical disk.

[0215] An embodiment of the present application also provides a computer program product, including a computer program, which implements the above-mentioned battery tab welding quality detection method when executed by a processor.

[0216] The processor is the processor in the electronic device described in the above embodiment. The readable storage medium includes a computer readable storage medium, such as a computer read-only memory ROM, a random access memory RAM, a magnetic disk or an optical disk.

[0217] An embodiment of the present application further provides a chip, which includes a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run programs or instructions to implement the various processes of the above-mentioned battery tab welding quality detection method embodiment, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0218] It should be understood that the chip mentioned in the embodiments of the present application can also be called a system-level chip, a system chip, a chip system or a system-on-chip chip, etc.

[0219] It should be noted that, in this article, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0220] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a computer software product, which is stored in a storage medium (such as ROM / RAM, a disk, or an optical disk), and includes a number of instructions for a terminal (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0221] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

[0222] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0223] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A battery tab welding quality detection method, characterized in that: include: Obtain the internal resistance of the tab connection of the battery to be tested after welding; When the tab connection internal resistance is less than or equal to a first internal resistance threshold, charging and discharging the battery to be tested to obtain tab temperature data of the battery to be tested; Determining a first temperature rise rate of the battery to be tested based on the tab temperature data; The first temperature rise rate is compared with a target temperature rise rate, and a welding quality test result of the battery to be tested is determined according to the comparison result. The target temperature rise rate is the temperature rise rate of charging and discharging of a battery with qualified tab welding quality.

2. The battery tab welding quality detection method according to claim 1, characterized in that: The step of obtaining the lug temperature data of the battery to be tested includes: Sampling is performed at a sampling time interval to obtain the tab temperature data of the battery to be tested at multiple sampling moments; The determining, based on the tab temperature data, a first temperature rise rate of the battery to be tested, comprises: The first temperature rise rate corresponding to each sampling moment is determined based on the tab temperature data corresponding to each sampling moment.

3. The battery tab welding quality detection method according to claim 2, characterized in that: The first temperature rise rate is determined by the following steps: Determine the change in the lug temperature at the current sampling moment based on the lug temperature data at the current sampling moment and the lug temperature data at the previous sampling moment; The first temperature rise rate at the current sampling moment is determined based on the test duration corresponding to the current sampling moment and the tab temperature change.

4. The battery tab welding quality detection method according to claim 2, characterized in that: The comparing the first temperature rise rate with the target temperature rise rate, and determining the welding quality test result of the battery to be tested according to the comparison result, comprises: The first temperature rise rate corresponding to the sampling moment is compared with the target temperature rise rate, and the welding quality detection result of the battery to be tested is determined according to the comparison result.

5. The battery tab welding quality detection method according to any one of claims 1 to 4, characterized in that: The charging and discharging of the battery to be tested comprises: Discharging the battery under test at a constant current to a discharge cut-off voltage, and leaving it to rest for a first target time; According to the constant current charging mode or the step charging mode, the battery to be tested is charged to the charging cut-off voltage.

6. The battery tab welding quality detection method according to claim 5, characterized in that: The method further comprises: charging the battery to be tested according to the constant current charging mode, comparing the first temperature rise rate with the target temperature rise rate, and determining the welding quality detection result of the battery to be tested according to the comparison result, including: In a first timing period, when the first temperature rise rate corresponding to a sampling moment is greater than the target temperature rise rate, it is determined that the tab of the battery to be tested is poorly soldered, and the start time of the first timing period is the start time of charging the battery to be tested.

7. The battery tab welding quality detection method according to claim 5, characterized in that: The step of charging the battery to be tested according to the step charging mode, comparing the first temperature rise rate with the target temperature rise rate, and determining the welding quality detection result of the battery to be tested according to the comparison result, comprises: In the second timing period, when the first temperature rise rate at the corresponding sampling moment is greater than the target temperature rise rate, it is determined that the tab of the battery to be tested is poorly welded, and the starting time of the second timing period is the moment when the current of the battery to be tested is greater than or equal to the first current threshold.

8. The battery tab welding quality detection method according to any one of claims 1 to 4, characterized in that: After obtaining the tab connection internal resistance of the battery to be tested after welding, the method further includes: When the tab connection internal resistance is greater than the first internal resistance threshold, it is determined that the tab of the battery to be tested is poorly soldered.

9. A battery tab welding quality detection device, characterized in that: include: The first processing module is used to obtain the internal resistance of the tab connection of the battery to be tested after welding; A second processing module is used to charge and discharge the battery to be tested and obtain the tab temperature data of the battery to be tested when the tab connection internal resistance is less than or equal to a first internal resistance threshold; A third processing module, used for determining a first temperature rise rate of the battery to be tested based on the tab temperature data; The fourth processing module is used to compare the first temperature rise rate with the target temperature rise rate, and determine the welding quality test result of the battery to be tested according to the comparison result, wherein the target temperature rise rate is the temperature rise rate of charging and discharging of a battery with qualified tab welding quality.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the battery tab welding quality detection method as described in any one of claims 1 to 8 is implemented.

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