Weld joint evaluation method and device, storage medium and electronic equipment

Abstract

The invention provides a welding seam evaluation method and device, a storage medium and electronic equipment. Multiple groups of gas injection tests are performed on a battery; obtaining breathing times corresponding to each group of gas injection tests; obtaining a fatigue life curve of the weld joint of the battery in the whole life cycle based on the breathing times of each group of gas injection tests; carrying out multi-circle charging and discharging tests on the battery, and obtaining fatigue strength of the corresponding charging and discharging tests; and determining the reliability of the battery weld joint according to the fatigue strength of each charge-discharge test, the fatigue life curve and a preset loss degree upper limit value. The charging and discharging test can be accurately simulated through the charging and discharging test to obtain the fatigue life curve, then the charging and discharging test is carried out to acquire the fatigue life, and the fatigue loss degree of the battery weld joint is calculated based on the fatigue life curve, so that whether the reliability of the battery weld joint meets the requirement or not is accurately evaluated, and the method is convenient and rapid; and the evaluation result is relatively accurate.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and particularly to a weld evaluation method, device, storage medium, and electronic device. Background Art

[0002] Lithium batteries are usually assembled from a housing, a cover plate, and a wound core. The wound core is placed into the housing, and then the housing and the cover plate are connected together by laser welding to ensure the physical isolation of the wound core from the outside.

[0003] During the use of the battery, during the charging process, the electrode sheets that make up the wound core will thicken; during the discharging process, the electrode sheets that make up the wound core will recover somewhat; the change in the thickness of the electrode sheets will cause the housing, mainly the surfaces parallel to the electrode sheets, to bulge out and then recover, then bulge out and recover again, in a cyclic periodical change similar to breathing, and mechanical fatigue damage will occur to its housing. The damage to the housing will lead to cracking, the electrolyte inside the battery will leak, and substances such as moisture from the outside will enter the battery, affecting the performance of the battery and even causing safety accidents. Therefore, how to evaluate the reliability of the housing during the entire life cycle of the battery has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0004] In view of the above problems, the present invention provides a weld evaluation method, device, storage medium, and electronic device that overcome the above problems or at least partially solve the above problems.

[0005] In a first aspect, a weld evaluation method includes:

[0006] Performing multiple groups of gas injection tests on the battery, wherein the maximum pressure of the gas injected in different groups of air injection tests is different, and each group includes multiple charge and discharge tests, and the maximum pressure of the gas injected in the multiple charge and discharge tests within the same group is the same;

[0007] Obtaining the number of breaths corresponding to each group of gas injection tests, wherein one group of gas injection tests corresponds to one number of breaths, and the number of breaths represents the number of charge and discharge tests corresponding to when the weld of the battery cracks during the process of the group of gas injection tests;

[0008] Based on the number of breaths of each group of gas injection tests, obtaining the fatigue life curve of the weld of the battery during the entire life cycle;

[0009] Performing multiple cycles of charge and discharge tests on the battery and obtaining the fatigue strength of the corresponding charge and discharge tests, wherein one cycle of charge and discharge test corresponds to one fatigue strength;

[0010] Determining the reliability of the battery weld according to the fatigue strength of each cycle of charge and discharge test, the fatigue life curve, and a preset upper limit value of the loss degree.

[0011] Optionally, in some alternative embodiments, each process of the charging and discharging test includes:

[0012] Inject gas into the battery within a first time range to make the gas pressure in the battery reach the maximum pressure corresponding to the air injection test;

[0013] Control the gas pressure in the battery to remain constant at the corresponding maximum pressure within a second time range;

[0014] Release the gas in the battery within a third time range to make the gas pressure in the battery return to the pressure before the gas injection;

[0015] Control the gas pressure in the battery to remain constant at the pressure before the gas injection within a fourth time range.

[0016] Optionally, in some alternative embodiments, obtaining the number of breaths corresponding to each group of gas injection tests includes:

[0017] For any group of gas injection tests, during multiple charging and discharging tests of this group of gas injection tests, detect whether the battery leaks;

[0018] If the battery leaks, determine that the weld of the battery is cracked, and record the number of charging and discharging tests performed until the weld of the battery is cracked as the number of breaths of this group of gas injection tests.

[0019] Optionally, in some alternative embodiments, obtaining the fatigue life curve of the weld of the battery during the entire life cycle based on the number of breaths of each group of gas injection tests includes:

[0020] Fit the fatigue life curve of the weld of the battery during the entire life cycle according to the fatigue strength and the number of breaths corresponding to each group of gas injection tests, where the vertical axis of the fatigue life curve is the fatigue strength and the horizontal axis of the fatigue life curve is the number of breaths.

[0021] Optionally, in some alternative embodiments, performing multiple charge-discharge tests on the battery and obtaining the fatigue strength corresponding to the corresponding charge-discharge tests includes:

[0022] Perform multiple charge-discharge tests on the battery, where one cycle of charge-discharge test includes a charging process, a first static process, a discharging process, and a second static process;

[0023] For any one cycle of charge-discharge test, collect and calculate the corresponding fatigue strength, where one cycle of charge-discharge test corresponds to one fatigue strength.

[0024] Optionally, in some alternative embodiments, for any charge-discharge test, collecting and calculating the corresponding fatigue strength includes:

[0025] For any charge-discharge test, during the charge-discharge test, collect the maximum expansion force and the minimum expansion force received by the large surface of the battery through a pressure sensor;

[0026] Calculate the expansion force difference between the maximum expansion force and the minimum expansion force;

[0027] Calculate the ratio of the expansion force difference to the area of the large surface of the battery to obtain the actual pressure received by the large surface of the battery, and record the actual pressure received by the large surface of the battery as the fatigue strength of the battery in this charge-discharge test.

[0028] Optionally, in some alternative embodiments, determining the reliability of the battery weld according to the fatigue strength of each charge-discharge test, the fatigue life curve, and a preset upper limit value of the loss degree includes:

[0029] For the fatigue strength of any charge-discharge test, input the fatigue strength into the fatigue life curve graph to obtain the corresponding number of breaths, where one fatigue strength corresponds to one number of breaths;

[0030] Accumulate the reciprocals of the numbers of breaths to obtain the fatigue loss degree of the battery weld;

[0031] If the fatigue loss degree of the battery weld is less than the upper limit value of the loss degree, it is determined that the reliability of the battery weld meets the requirements;

[0032] If the fatigue loss degree of the battery weld is greater than the upper limit value of the loss degree, it is determined that the reliability of the battery weld does not meet the requirements.

[0033] In a second aspect, a weld evaluation device includes: a gas injection unit, a breathing number obtaining unit, a fatigue curve evaluation unit, a charge-discharge test unit, and a reliability evaluation unit;

[0034] The gas injection unit is configured to perform multiple groups of gas injection tests on the battery, where the maximum pressures of the gases injected in different groups of air injection tests are different, and each group includes multiple charge-discharge gas tests, and the maximum pressures of the gases injected in the multiple charge-discharge gas tests within the same group are the same;

[0035] The breathing number obtaining unit is configured to obtain the breathing numbers corresponding to each group of gas injection tests, where one group of gas injection tests corresponds to one breathing number, and the breathing number represents the number of charge-discharge gas tests corresponding to the cracking of the battery weld during the gas injection test of this group;

[0036] The fatigue curve evaluation unit is configured to obtain the fatigue life curve of the weld of the battery within the entire life cycle based on the number of breaths in each group of gas injection tests;

[0037] The charge and discharge test unit is configured to perform multiple cycles of charge and discharge tests on the battery and obtain the fatigue strength corresponding to the respective charge and discharge tests, wherein one cycle of charge and discharge test corresponds to one fatigue strength;

[0038] The reliability evaluation unit is configured to determine the reliability of the battery weld according to the fatigue strength of each cycle of charge and discharge test, the fatigue life curve, and a preset upper limit value of the loss degree.

[0039] In a third aspect, a computer-readable storage medium has a program stored thereon, and the program is executed by a processor to perform the weld evaluation method described in any one of the above.

[0040] In a fourth aspect, an electronic device includes at least one processor, at least one memory connected to the processor, and a bus; wherein, the processor and the memory communicate with each other through the bus; the processor is configured to call program instructions in the memory to execute the weld evaluation method described in any one of the above.

[0041] By means of the above technical solutions, a weld evaluation method, device, storage medium, and electronic device provided by the present invention perform multiple groups of gas injection tests on the battery. Among them, the maximum pressure of the gas injected in different groups of air injection tests is different, and each group includes multiple charge and discharge gas tests, and the maximum pressure of the gas injected in the multiple charge and discharge gas tests within the same group is the same; obtain the number of breaths corresponding to each group of gas injection tests, wherein one group of gas injection tests corresponds to one number of breaths, and the number of breaths represents the number of charge and discharge gas tests corresponding to the cracking of the battery weld during the process of the group of gas injection tests; obtain the fatigue life curve of the weld of the battery within the entire life cycle based on the number of breaths in each group of gas injection tests; perform multiple cycles of charge and discharge tests on the battery and obtain the fatigue strength corresponding to the respective charge and discharge tests, wherein one cycle of charge and discharge test corresponds to one fatigue strength; determine the reliability of the battery weld according to the fatigue strength of each cycle of charge and discharge test, the fatigue life curve, and a preset upper limit value of the loss degree. It can be seen from this that the present invention can accurately simulate the charge and discharge test through the charge and discharge gas test, obtain the fatigue life curve, then perform the charge and discharge test to collect the fatigue life, and calculate the fatigue loss degree of the battery weld based on the fatigue life curve, so as to accurately evaluate whether the reliability of the battery weld meets the requirements, which is not only convenient and fast, but also the evaluation result is relatively accurate.

[0042] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. And in order to make the above and other objects, features and advantages of the present invention more obvious and understandable, the following specifically illustrates the specific implementation manners of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of illustrating the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0044] Figure 1 A schematic diagram showing the first change situation of the expansion force provided by the present invention;

[0045] Figure 2 A schematic diagram showing the second change situation of the expansion force provided by the present invention;

[0046] Figure 3 A simplified diagram showing a change situation of the expansion force provided by the present invention;

[0047] Figure 4 A flowchart showing a weld evaluation method provided by the present invention;

[0048] Figure 5 A schematic diagram showing a ventilation test result provided by the present invention;

[0049] Figure 6 A schematic diagram showing a battery test tooling provided by the present invention;

[0050] Figure 7 A schematic diagram showing the variation law of the ventilation test air pressure provided by the present invention;

[0051] Figure 8 A schematic diagram showing an S-N curve provided by the present invention;

[0052] Figure 9 A schematic diagram showing the change situation of the expansion force during charge and discharge tests provided by the present invention;

[0053] Figure 10 A schematic diagram showing a fatigue strength curve provided by the present invention;

[0054] Figure 11 A schematic diagram showing a weld fatigue life curve provided by the present invention;

[0055] Figure 12 A schematic diagram showing the fatigue loss degree of a weld provided by the present invention;

[0056] Figure 13 Shows a schematic structural diagram of a weld evaluation device provided by the present invention;

[0057] Figure 14 Shows a schematic structural diagram of an electronic device provided by the present invention. Specific embodiments

[0058] The battery includes a housing and a wound core disposed in the housing. The housing includes an outer shell and a cover plate. The wound core is disposed in the outer shell and is sealed by welding the cover plate to the outer shell. It is also necessary to inject electrolyte inside the housing, and the electrolyte is generally injected through an opening in the cover plate. The inventors of this solution found through research that during the use of the battery, the charge and discharge of the battery cause the housing to have a certain cyclic strain, and this cyclic strain causes mechanical fatigue damage to the housing, eventually leading to the fracture of the housing. Since the outer shell is an integral body, the main damage location is at the welding position between the outer shell and the cover plate. Therefore, the reliability of the housing can be evaluated through the weld. Based on this, the present invention provides a weld evaluation method, device, storage medium, and electronic device.

[0059] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided so that the present invention can be more thoroughly understood and the scope of the present invention can be completely conveyed to those skilled in the art.

[0060] The overall process of the present invention includes: obtaining the battery cyclic expansion force through charge and discharge gas tests, designing experiments to obtain the fatigue S-N curve of the weld, calculating the fatigue loss degree of the weld through actual charge and discharge tests, and reliability evaluation.

[0061] (1) Obtaining the battery cyclic expansion force through charge and discharge gas tests. According to the relationship formula between force and pressure: F = P×S, the present invention can infer and obtain the fatigue strength of the weld based on the above formula, where F represents the expansion force of the battery, P represents the pressure in the formula (corresponding to the fatigue strength mentioned in the present invention), and S in the formula represents the area of the outer shell parallel to the electrode surface, that is, the area of the large surface of the battery (in the following description, S is used to describe the fatigue strength of the present invention, rather than the area in the above formula).

[0062] (2) Designing experiments to obtain the fatigue S-N curve of the weld of the battery housing, where S represents the fatigue strength received by the weld, and N represents the fatigue life of the weld under the fatigue strength S, that is, the weld will crack after fatigue N times under the fatigue strength S.

[0063] (3) Calculate the fatigue loss degree of the weld by actual charge and discharge tests. As mentioned above, the fatigue strength Si and fatigue life Ni corresponding to each cycle of the battery have been obtained (i is the cycle number code). Then, for each charge and discharge cycle, the fatigue loss degree of the weld Wi = 1 / Ni. The fatigue loss degree of the weld during the entire life cycle of the battery , where n represents the total number of cycles during the entire life cycle of the battery (for example, if it is required that a certain battery undergoes more than 2000 cycles without weld cracking, then n = 2000).

[0064] It should be noted that during the actual charge and discharge cycle of the battery, the cyclic expansion force changes (because during the cycle, when the battery is at the same SOC (State of Charge, the percentage of the remaining battery charge to the nominal capacity), the thickness of the electrode gradually increases), that is, the fatigue strength suffered by the weld also changes. According to the cyclic expansion force after each cycle and the weld fatigue S-N curve, the fatigue strength suffered by the weld for each cycle and the fatigue life N of the weld under the corresponding fatigue strength can be obtained.

[0065] (4) Reliability assessment. If the fatigue loss degree W of the weld during the entire life cycle of the battery is < a, it is considered that the weld has no risk of cracking during the entire life cycle of the battery; if the fatigue loss degree W of the weld during the entire life cycle of the battery is ≥ a, it is considered that the weld has a risk of cracking during the entire life cycle of the battery, and the point where W = a indicates that the weld just cracks. Theoretically, the value of a should be 1, indicating that the fatigue loss degree reaches 100%; however, in actual situations, metal fatigue has a slow loss in the early stage and will accelerate after reaching a certain level (for example: 60% - 80%, which is related to the material properties); therefore, the value of a can be 0.6 to improve the reliability of the assessment.

[0066] Taking a lithium iron phosphate 166Ah battery as the experimental object, the battery undergoes charge and discharge cycle tests in an incubator at 45°C. During the test, the battery is clamped by a fixture, and the cyclic expansion force of the large surface is detected by a pressure sensor. Exemplarily, the charge and discharge cycle test process: Step 1, constant current charging at 0.5C until the voltage reaches 3.65V, then constant voltage charging until the current is less than or equal to 0.05C (charging time is about 2 hours); Step 2, rest for 30 minutes; Step 3, constant current discharging at 1C until the voltage is 2.5V (discharging time is about 1 hour); Step 4, rest for 30 minutes. The charge and discharge test is cyclically executed according to the change rule of Step 1 to Step 4. It should be noted that: the present invention can set the time of Step 1 - Step 4 according to different working conditions, and the present invention is not limited thereto.

[0067] Repeat the above steps 1 to 4 until the SOH (State of Health) of the battery drops to 80%. Here, C represents the rate, 1C = 166A; the SOH of each cycle is the discharge capacity of each cycle divided by the discharge capacity of the first cycle. One cycle of the battery means the battery has completed a process from step 1 to step 4 once.

[0068] The change in the expansion force caused by the above charge-discharge cycle test process is as Figure 1 shown. From Figure 1 it can be found that when the battery is in the same state, the expansion force gradually increases. To facilitate a clearer observation of the actual change in the expansion force, the present invention plots the expansion force of two cycles against the charge-discharge rate, as Figure 2 shown. Here, a negative rate indicates discharge; a rate equal to 0 indicates standby; a positive rate indicates charge. It can be found from the figure that during the charging process, the expansion force shows an increasing trend; during the standby process, the expansion force basically remains unchanged; during the discharging process, the expansion force shows a decreasing trend. Thus, it can be known that the cyclic expansion force of the battery during the charge-discharge test is periodically changing. Therefore, according to the change law of the cyclic expansion force during the charge-discharge test, the change law of the air pressure during the charge-discharge test can be set, that is, the change law of the air pressure during the charge-discharge test is set to be the same as the change law of the cyclic expansion force during the charge-discharge test, so as to simulate the breathing process of the charge-discharge test and improve the evaluation reliability.

[0069] Optionally, the present invention can simplify the change situation of the Figure 2 cyclic expansion force into Figure 3 , where the time is scaled down proportionally. In the figure, F1 represents the maximum expansion force of each cycle, and F2 represents the minimum expansion force of each cycle.

[0070] As Figure 4 shown, the present invention provides a weld evaluation method, including: S100, S200, S300, S400, and S500;

[0071] S100. Conduct multiple groups of gas injection tests on the battery. Among them, the maximum pressure of the gas injected in different groups of air injection tests is different, and each group includes multiple charge-discharge tests. The maximum pressure of the gas injected in multiple charge-discharge tests within the same group is the same;

[0072] Optionally, during the use of the battery and the charging process, the electrode sheets that make up the core will thicken. During the discharging process, the electrode sheets that make up the core will recover somewhat. During continuous charge and discharge cycles, the change in the thickness of the electrode sheets will cause the outer shell, mainly the surface parallel to the electrode sheets, to bulge out and then recover, bulge out and then recover again, in a cyclic period change similar to respiration. Mechanical fatigue damage will occur at the welding position between the outer shell and the cover plate. The welding position between the outer shell and the cover plate is called the weld seam. When the mechanical fatigue of the weld seam reaches a certain level, the weld seam will crack, the electrolyte inside the battery will leak, and substances such as moisture from the outside will enter the battery interior, affecting the performance of the battery and even causing safety accidents. Therefore, the present invention can, through an inflation test, simulate the mechanical fatigue damage caused by the charge and discharge of the battery, thereby evaluating the service life of the weld seam of the battery, further evaluating the reliability of the weld seam, and thus evaluating the reliability of the housing. The present invention does not limit this.

[0073] Optionally, during the use of the battery, different numbers of charge and discharge processes and different magnitudes of current will cause different degrees of mechanical fatigue damage to the battery. Therefore, the present invention simulates different charge and discharge conditions by injecting gases at different pressures. One charge and discharge gas test can be correspondingly understood as one charge and discharge process. The present invention does not limit this.

[0074] Also, even when the battery is used under the same charge and discharge condition, the battery needs to undergo multiple charge and discharge cycles before the weld seam cracks. Therefore, the present invention can conduct tests in groups. The same group of tests corresponds to multiple cycles under the same charge and discharge condition. The present invention does not limit this.

[0075] Optionally, the present invention obtains the fatigue S-N curve of the weld seam through experimental design. For example, based on the charge and discharge principle of steps 1 to 4 above, the test processes of steps 1.1 to 1.4 of the present invention are set. The present invention does not limit this. When it is necessary to test the fatigue loss under different conditions, the present invention can set different steps 1 - 4, thereby further adjusting steps 1.1 - 1.4 to improve the test applicability.

[0076] That is, in some optional embodiments, the process of each charge and discharge gas test includes:

[0077] Step 1.1, within a first time range, inject gas into the battery to make the gas pressure inside the battery reach the maximum pressure corresponding to the air injection test;

[0078] Step 1.2, within a second time range, control the gas pressure inside the battery to remain at the corresponding maximum pressure unchanged;

[0079] Step 1.3, within a third time range, release the gas inside the battery to make the gas pressure inside the battery return to the pressure before the gas injection;

[0080] Step 1.4: Within the fourth time range, control the gas pressure inside the battery to remain unchanged from the pressure before the gas injection. Among them, the law of air pressure change in the charge and discharge test is determined according to the law of cyclic expansion force change in the actual charge and discharge test. That is, the arrangement order, duration, and magnitude of air pressure change in the first time range, second time range, third time range, and fourth time range can all be determined according to the law of expansion force change in the preset charge and discharge test, which will be described in detail below.

[0081] Optionally, the present invention mainly makes the welds receive a certain pressure by introducing a certain amount of gas into the closed battery case, so that the welds reach a certain fatigue strength. The detailed experimental details are as follows: Take a semi-finished battery without electrolyte, which may only include a case and a cover plate. Connect a hose to the liquid injection hole on the battery cover plate, and then use AB glue to seal the contact position between the hose and the liquid injection hole to ensure the airtightness of the battery case; In order to avoid other weak areas of the battery cracking prior to the welds during the experiment and affecting the experimental results, AB glue can be coated on other weak areas of the battery, such as the explosion-proof valve. Then clamp the battery in the large surface direction, connect the hose to the ventilation device, and the ventilation device is connected to the gas source. The ventilation device can automatically control the amount of gas introduced into the battery case and the ventilation frequency; When the welds of the battery crack, the battery will leak air, and the ventilation device cannot raise the air pressure inside the battery to the set value within the set time, or detects air leakage, and the ventilation device will stop ventilation and alarm.

[0082] That is, optionally, in some alternative embodiments, a fixing glue is coated on the weak parts of the battery to prevent the weak parts of the battery from cracking prior to the welds, where the weak parts of the battery are areas weaker than the welds;

[0083] The other surfaces other than the large surfaces of the battery are fixed by fixing parts to prevent the other surfaces other than the large surfaces of the battery from expanding. The large surfaces of the battery are the two largest side surfaces among the six side surfaces of the battery.

[0084] It should be noted that when introducing 0.3 MPa of gas into the semi-finished battery, that is, the ventilation air pressure P' = 0.3 MPa, the measured expansion force of the large surface of the battery is only about 450 kgf, and the experimental results are as Figure 5 shown, which does not conform to the actual situation. Because during the actual cycle of the battery, the expansion force of the large surface of the battery is mainly caused by the change in the thickness of the electrode sheets; If gas is directly filled into the battery, the six surfaces of the battery case will bulge outwards, resulting in a smaller actual expansion force of the large surface of the battery, which is less than the force value calculated from the ventilation air pressure P' and the area S' of the large surface; Then calculating the fatigue strength of the welds through the ventilation air pressure P' will be greater than the actual fatigue strength S received by the welds, resulting in a large experimental error.

[0085] Based on the above situation, in the charging and discharging gas test of the present invention, except for the two surfaces in the large surface direction of the battery, the other four surfaces are limited by a tooling to prevent the surfaces other than the large surface of the battery from bulging outwards, simulating the real charging and discharging working conditions (in the real working conditions of the battery, the bulging of the shell is mainly concentrated on the large surface of the battery), and avoiding the interference of other surfaces. At the same time, during the charging and discharging gas test, the expansion force of the large surface of the battery can also be detected, and then the pressure received by the large surface can be calculated according to the actual expansion force of the large surface of the battery, that is, the actual fatigue strength received by the weld. The present invention does not limit this.

[0086] The purpose of using the limiting tooling for the other four surfaces is to reduce the expansion of the other surfaces, ensure the stable force on the large surface during the experiment, and prevent it from fluctuating with the experiment time. The deformation coefficient of the material used for the limiting tooling should be small, and steel and the like can be used. The tooling is as Figure 6 shown. Among them, the top, bottom, and side limiting toolings can be combined by bolts; the limiting tooling is connected through the liquid injection hole of the battery to facilitate ventilation into the battery interior. The four surfaces of up, down, left, and right are all limited to prevent the four surfaces from expanding and moving, affecting the force on the large surface and the evaluation conclusion.

[0087] Optionally, the ventilation volume and the ventilation change rule refer to Figure 7 shown. Figure 7 The ordinate of is the fatigue strength value. Among them, step 1.1: within the time range of 0s - 20s (the first time range), the air pressure gradually increases, which is the pressure increase process, equivalent to the battery charging process, and the expansion force gradually increases; step 1.2: within the time range of 20s - 25s (the second time range), the air pressure remains unchanged, which is the pressure holding process, equivalent to the battery resting process, and the expansion force remains unchanged; step 1.3: within the time range of 25s - 35s (the third time range), the air pressure gradually decreases, which is the pressure decrease process, equivalent to the battery discharging process, and the expansion force gradually decreases; step 1.4: within the time range of 35s - 40s (the fourth time range), the air pressure remains unchanged, which is the pressure holding process, equivalent to the battery resting process, and the expansion force remains unchanged (the time for the air pressure change in each step is proportional to the time of the battery cycling process).

[0088] Optionally, each breath is a process of completing steps 1.1 to 1.4. During the charging and discharging gas test, the fatigue damage to the weld for each breath is equivalent to the fatigue loss of the weld for one battery charging and discharging cycle. That is, through the charging and discharging gas test of the empty shell battery, the charging and discharging process of the actual battery is simulated to evaluate the reliability of the battery shell.

[0089] S200. Obtain the number of breaths corresponding to each group of gas injection tests. Among them, one group of gas injection tests corresponds to one number of breaths, and the number of breaths represents the number of charging and discharging gas tests corresponding to the cracking of the battery weld during the process of the group of gas injection tests;

[0090] Optionally, in some alternative embodiments, S200 includes Step 2.1 and Step 2.2;

[0091] Step 2.1: For any group of gas injection tests, during multiple charge and discharge tests of the group of gas injection tests, detect whether the battery leaks air;

[0092] Step 2.2: If the battery leaks air, determine that the weld of the battery is cracked, and record the number of charge and discharge tests performed until the weld of the battery cracks as the breathing times of the group of gas injection tests.

[0093] By the above method, using semi-finished batteries, or even battery casings, without the need for a wound core, the breathing times of the battery under different maximum pressures can be detected, avoiding the use of actual batteries for charge and discharge cycles, greatly saving costs and time.

[0094] S300: Based on the breathing times of each group of gas injection tests, obtain the fatigue life curve of the weld of the battery throughout its life cycle.

[0095] For example, in some alternative embodiments, the obtaining of the fatigue life curve of the weld of the battery throughout its life cycle based on the breathing times of each group of gas injection tests includes Step 3.1;

[0096] Step 3.1: According to the fatigue strength and breathing times corresponding to each group of gas injection tests, fit to obtain the fatigue life curve of the weld of the battery throughout its life cycle, where the vertical axis of the fatigue life curve is the fatigue strength and the horizontal axis of the fatigue life curve is the breathing times.

[0097] Optionally, in the charge and discharge test of the present invention, when ventilating the battery casing, the maximum ventilation air pressure is P', and the maximum pressure of each group of gas injection tests can be defined as the fatigue strength, that is, the fatigue strength S received by the weld = P', thus simplifying the method and improving the experimental efficiency. By introducing gases with different maximum pressures into the battery, different battery pressures are obtained, that is, the weld receives different fatigue strengths. Or, in the charge and discharge test, through a voltage sensor, the large surface expansion force is collected, and the large surface pressure of the battery is determined by calculation as the fatigue strength.

[0098] Exemplarily, the fatigue strengths S are respectively set to 0.3 MPa, 0.25 MPa, 0.2 MPa, and 0.15 Mpa, and air is ventilated into the battery casing according to Figure 7 the air pressure change rule, and the breathing times, that is, the fatigue life N, under each fatigue strength S are recorded, obtaining the S-N curve as shown in Figure 8 , where the breathing times N are the breathing times when the weld breaks. And, N×S^3.731 = 7.543, where R 2= 0.99, indicating a good fitting degree. It should be noted that the R-squared value is an index of the fitting degree of the trend line. Its numerical value can reflect the fitting degree between the estimated value of the trend line and the corresponding actual data. The higher the fitting degree, the higher the reliability of the trend line. The R-squared value is a numerical value ranging from 0 to 1. When the R-squared value of the trend line is equal to 1 or close to 1, its reliability is the highest; otherwise, the reliability is relatively low. The R-squared value is also called the coefficient of determination.

[0099] It should be noted that the law of air pressure change includes the arrangement order, duration of the first time range, second time range, third time range, and fourth time range, as well as the magnitude of air pressure change, etc. The arrangement order, duration of each time range, and the magnitude of air pressure change are sequentially cycled for charging and discharging tests according to the arrangement order, duration of the first time range, second time range, third time range, and fourth time range, as well as the magnitude of air pressure change. Exemplarily, the duration of the first time range is 20s, the duration of the second time range is 5s, the duration of the third time range is 10s, and the duration of the fourth time range is 5s. Within the first time range, the air pressure increases from small to large. Within the second time range, the air pressure remains unchanged. Within the third time range, the air pressure decreases from large to small. Within the fourth time range, the air pressure remains unchanged. Refer to Figure 7 shown. The law of air pressure change is determined according to the law of cyclic expansion force change in the preset charge and discharge test, which can simulate the real air breathing situation of the battery during charge and discharge, that is, simulate the real working condition of mechanical fatigue damage of the battery case weld, and ensure the reliability of battery case life assessment.

[0100] Optionally, the law of air pressure change in the charge and discharge test is equal to the law of cyclic expansion force change in the charge and discharge test, so as to ensure the consistency between the charge and discharge test process and the charge and discharge test process, and improve the reliability of weld assessment. Further, each time range in the law of air pressure change in the charge and discharge test can also be proportionally reduced according to the law of cyclic expansion force change in the charge and discharge test, which can improve the efficiency of the charge and discharge test on the basis of ensuring the assessment reliability. Figure 7 The law of air pressure change in

[0101] S400. Perform multiple cycles of charge and discharge tests on the battery and obtain the fatigue strength corresponding to the charge and discharge test. Among them, one cycle of charge and discharge test corresponds to one fatigue strength.

[0102] For example, in some optional embodiments, S400 includes: step 4.1 and step 4.2;

[0103] Step 4.1. Perform multiple cycles of charge and discharge tests on the battery. Among them, one cycle of charge and discharge test includes a charging process, a first static process, a discharging process, and a second static process.

[0104] Step 4.2: For any charge-discharge test cycle, collect and calculate the corresponding fatigue strength, where one charge-discharge test cycle corresponds to one fatigue strength.

[0105] Optionally, in some alternative embodiments, Step 4.2 includes: Step 5.1, Step 5.2, and Step 5.3;

[0106] Step 5.1: For any charge-discharge test cycle, during the charge-discharge test, collect, via a pressure sensor, the maximum expansion force and the minimum expansion force received by the large surface of the battery.

[0107] Step 5.2: Calculate the expansion force difference between the maximum expansion force and the minimum expansion force.

[0108] Step 5.3: Calculate the ratio of the expansion force difference to the area of the large surface of the battery to obtain the actual pressure received by the large surface of the battery, and record the actual pressure received by the large surface of the battery as the fatigue strength of the battery in this charge-discharge test.

[0109] Optionally, during the charge-discharge cycle of the battery, the expansion force changes. In the present invention, the maximum and minimum values of each charge-discharge cycle are taken to reflect the change in the expansion force of the large surface of the battery, and the results are as Figure 9 shown. It should be noted that the charging process, the first static process, the discharging process, and the second static process of each charge-discharge test cycle are the same, and the charging rate of each charging process, the static time of the first static process, the discharging rate of the discharging process, and the static time of the second static process are the same to ensure the same battery state and improve the test reliability. Among them, both the first static process and the second static process can improve the battery performance stability.

[0110] Optionally, the difference between the maximum and minimum values of each battery cycle (considering the dynamic fatigue effect under similar respiration, the dynamic fatigue caused by air pressure change), and then divided by the area of the outer shell parallel to the electrode surface, can obtain the fatigue strength of each battery cycle (the actual fatigue strength S of the battery), and the results are as Figure 10 shown.

[0111] S500: Determine the reliability of the battery weld according to the fatigue strength of each charge-discharge test cycle, the fatigue life curve, and a preset upper limit value of loss degree.

[0112] For example, in some alternative embodiments, S500 includes: Step 6.1, Step 6.2, Step 6.3, and Step 6.4;

[0113] Step 6.1: For the fatigue strength of any charge-discharge test cycle, input the fatigue strength into the fatigue life curve graph to obtain the corresponding number of breaths, where one fatigue strength corresponds to one number of breaths;

[0114] Step 6.2: Accumulate the reciprocals of each of the respiration frequencies to obtain the fatigue loss degree of the battery weld seam.

[0115] Step 6.3: If the fatigue loss degree of the battery weld seam is less than the upper limit value of the loss degree, determine that the reliability of the battery weld seam meets the requirements.

[0116] Step 6.4: If the fatigue loss degree of the battery weld seam is greater than the upper limit value of the loss degree, determine that the reliability of the battery weld seam does not meet the requirements.

[0117] Optionally, the present invention can calculate the loss degree of the weld seam of the battery over the entire life cycle based on the reciprocal of the respiration frequency corresponding to the charge-discharge cycle number in the fatigue life curve, so as to evaluate the reliability of the weld seam of the battery over the entire life cycle.

[0118] Optionally, the present invention can actually measure the S value of a certain cycle (cycle number), substitute it into Figure 8 the S-N curve shown, and obtain the N value corresponding to the S value. Each S value of each cycle can correspond to an N value. That is, the present invention can, according to the S-N curve of the weld seam, obtain the fatigue life N value corresponding to the fatigue strength of each cycle, and obtain the minimum respiration frequency that can be tolerated in this cycle.

[0119] Optionally, each S of each cycle is substituted into Figure 8 the curve shown to obtain the respiration frequency N under the S value of each cycle. The result is as shown in Figure 11 shown. Among them, Figure 11 the ordinate of : the fatigue life N of the weld seam (the number of cycles that the battery with a cracked weld seam can cycle under a specific air pressure). Figure 11 the abscissa of : the number of cycles actually cycled by the battery (the number of cycles of a normal battery).

[0120] Optionally, according to the fatigue strength and corresponding fatigue life of each cycle of the weld seam, calculate the fatigue loss degree Wi = 1 / Ni of the weld seam when the battery cycles one circle (Ni represents the i-th cycle, and Wi represents the fatigue loss degree of the i-th cycle). The result is as shown in Figure 12 shown. That is, the fatigue loss degree of each cycle: 1 / Ni.

[0121] For example, in combination with the foregoing example, the present invention can calculate the fatigue loss degree of the weld seam of the battery over the entire life cycle . If the upper limit a of the fatigue loss degree of the weld seam is 0.6, since W = 0.22 < 0.6, the weld seam is reliable during the entire life cycle of the battery.

[0122] It can be found from the implementation cases that when calculating and predicting the fatigue damage of the weld seam, it is necessary to first know the cyclic expansion force of the battery. If testing and collecting the data of the cyclic expansion force of the battery, it takes a long time. Through the present invention, the change of the expansion force during the entire life cycle of the battery can be predicted based on a small amount of measured data of the cyclic expansion force, improving the overall testing efficiency.

[0123] Although the operations are depicted in a particular order, this should not be construed as requiring the operations to be performed in the particular order shown or in sequential order. In certain circumstances, multitasking and parallel processing may be advantageous.

[0124] It should be understood that the various steps recited in the method embodiments of the present invention may be executed in a different order and / or in parallel. In addition, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this regard.

[0125] As Figure 13 shown, the present invention provides a weld seam evaluation device, including: a gas injection unit 100, a breathing times acquisition unit 200, a fatigue curve evaluation unit 300, a charge and discharge test unit 400, and a reliability evaluation unit 500;

[0126] The gas injection unit 100 is used to perform multiple groups of gas injection tests on the battery. Among them, the maximum pressure of the gas injected in different groups of air injection tests is different, and multiple charge and discharge tests are included in the same group. The maximum pressure of the gas injected in the multiple charge and discharge tests in the same group is the same;

[0127] The breathing times acquisition unit 200 is used to obtain the breathing times corresponding to each group of gas injection tests. Among them, one group of gas injection tests corresponds to one breathing time, and the breathing time represents the number of charge and discharge tests corresponding to the cracking of the battery weld seam during the gas injection test of this group;

[0128] The fatigue curve evaluation unit 300 is used to obtain the fatigue life curve of the weld seam of the battery during the entire life cycle based on the breathing times of each group of gas injection tests.

[0129] The charge and discharge test unit 400 is used to perform multiple cycles of charge and discharge tests on the battery and obtain the fatigue strength of the corresponding charge and discharge tests. Among them, one cycle of charge and discharge test corresponds to one fatigue strength;

[0130] The reliability evaluation unit 500 is used to determine the reliability of the battery weld seam according to the fatigue strength of each cycle of charge and discharge test, the fatigue life curve, and a preset upper limit value of the loss degree.

[0131] Optionally, in some alternative embodiments, the device further includes a charge and discharge test unit;

[0132] The gas charging and discharging test unit includes: a first time range sub-unit, a second time range sub-unit, a third time range sub-unit, and a fourth time range sub-unit;

[0133] The gas charging and discharging test unit is used for each process of the gas charging and discharging test;

[0134] The first time range sub-unit is used to inject gas into the battery within a first time range so that the gas pressure in the battery reaches the maximum pressure corresponding to the air injection test;

[0135] The second time range sub-unit is used to control the gas pressure in the battery to remain unchanged at the corresponding maximum pressure within a second time range;

[0136] The third time range sub-unit is used to release the gas in the battery within a third time range so that the gas pressure in the battery returns to the pressure before the gas injection;

[0137] The fourth time range sub-unit is used to control the gas pressure in the battery to remain unchanged at the pressure before the gas injection within a fourth time range.

[0138] Optionally, in some alternative embodiments, the breathing times acquisition unit 200 includes: a leakage detection sub-unit and a cracking determination sub-unit;

[0139] The leakage detection sub-unit is used to detect whether the battery leaks during multiple gas charging and discharging tests for any group of gas injection tests;

[0140] The cracking determination sub-unit is used to determine that the weld of the battery cracks if the battery leaks, and record the number of gas charging and discharging tests performed until the weld of the battery cracks as the breathing times of the group of gas injection tests.

[0141] Optionally, in some alternative embodiments, the fatigue curve evaluation unit 300 includes: a fatigue curve evaluation sub-unit;

[0142] The fatigue curve evaluation sub-unit is used to fit the fatigue life curve of the weld of the battery during its entire life cycle according to the fatigue strength and breathing times corresponding to each group of gas injection tests, where the vertical axis of the fatigue life curve is the fatigue strength and the horizontal axis of the fatigue life curve is the breathing times.

[0143] Optionally, in some alternative embodiments, the charge and discharge test unit 400 includes: a swelling force acquisition sub-unit, a swelling force difference sub-unit, and an actual pressure calculation sub-unit;

[0144] The expansion force acquisition subunit is configured to collect the maximum expansion force and the minimum expansion force received by the large surface of the battery through a pressure sensor during the charge and discharge test for any cycle of charge and discharge test;

[0145] The expansion force difference subunit is configured to calculate the expansion force difference between the maximum expansion force and the minimum expansion force;

[0146] The actual pressure calculation subunit is configured to calculate the ratio of the expansion force difference to the area of the large surface of the battery, obtain the actual pressure received by the large surface of the battery, and record the actual pressure received by the large surface of the battery as the fatigue strength of the battery in the current charge and discharge test.

[0147] Optionally, in some alternative embodiments, the S500 includes: a curve substitution subunit, a loss degree calculation subunit, a first evaluation result subunit, and a second evaluation result subunit;

[0148] The curve substitution subunit is configured to input the fatigue strength into the fatigue life curve graph for the fatigue strength of any cycle of charge and discharge test to obtain the corresponding number of breaths, where one fatigue strength corresponds to one number of breaths;

[0149] The loss degree calculation subunit is configured to accumulate the reciprocals of the numbers of breaths to obtain the fatigue loss degree of the battery weld;

[0150] The first evaluation result subunit is configured to determine that the reliability of the battery weld meets the requirements if the fatigue loss degree of the battery weld is less than the upper limit value of the loss degree;

[0151] The second evaluation result subunit is configured to determine that the reliability of the battery weld does not meet the requirements if the fatigue loss degree of the battery weld is greater than the upper limit value of the loss degree.

[0152] Regarding the device in the above embodiments, the specific manners in which each module performs operations have been described in detail in the embodiments related to the method, and will not be elaborated here.

[0153] The weld evaluation device includes a processor and a memory. The above gas injection unit, number of breaths acquisition unit, fatigue curve evaluation unit, etc. are all stored in the memory as program units, and the processor executes the above program units stored in the memory to implement corresponding functions.

[0154] An embodiment of the present invention provides a computer-readable storage medium, on which a program is stored, and when the program is executed by a processor, the weld evaluation method is implemented.

[0155] An embodiment of the present invention provides a processor for running a program, wherein the weld evaluation method is executed when the program runs.

[0156] As Figure 14 shown, an embodiment of the present invention provides an electronic device 700. The electronic device 70 includes at least one processor 701, at least one memory 702 connected to the processor 701, and a bus 703. Among them, the processor 701 and the memory 702 communicate with each other through the bus 703. The processor 701 is used to call program instructions in the memory 702 to execute the above-mentioned weld evaluation method. The electronic device herein may be a server, a PC, a PAD, a mobile phone, etc.

[0157] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses, electronic devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable devices generate a device for realizing the functions specified in one Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0158] In a typical configuration, an electronic device includes one or more processors (CPUs), a memory, and a bus. The electronic device may also include an input / output interface, a network interface, etc.

[0159] The memory may include non-permanent memory in the computer-readable medium, in the form of random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash memory (flash RAM). The memory includes at least one storage chip. The memory is an example of a computer-readable medium.

[0160] A computer-readable medium includes both permanent and non-permanent, removable and non-removable media and can implement information storage by any method or technology. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic tape disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to store information accessible by a computing device. As defined herein, a computer-readable medium does not include transitory computer-readable media such as modulated data signals and carrier waves.

[0161] In the description of the present invention, it should be understood that if terms such as "upper", "lower", "front", "rear", "left", and "right" are used to indicate the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated position or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention.

[0162] It should be noted that in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent in such process, method, commodity or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the existence of additional identical elements in the process, method, commodity or device comprising the element.

[0163] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0164] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. A weld evaluation method, characterized in that: include: The battery is subjected to multiple groups of gas injection tests, wherein the maximum pressure of the gas injected in different groups of air injection tests is different, and the same group includes multiple charging and discharging tests, and the maximum pressure of the gas injected in multiple charging and discharging tests in the same group is the same; Obtaining the number of breaths corresponding to each group of gas injection tests, wherein one group of gas injection tests corresponds to one number of breaths, and the number of breaths represents the number of gas charging and discharging tests corresponding to when cracks occur in the battery weld during the group of gas injection tests; Based on the number of breaths of each group of gas injection tests, a fatigue life curve of the weld of the battery over the entire life cycle is obtained; Perform multiple cycles of charge and discharge tests on the battery, and obtain fatigue strength of the corresponding charge and discharge tests, wherein one cycle of charge and discharge tests corresponds to one fatigue strength; The reliability of the battery weld is determined based on the fatigue strength of each cycle of charge and discharge testing, the fatigue life curve and a preset upper limit of the loss degree.

2. The method according to claim 1, characterized in that Each of the above-mentioned inflation and deflation tests includes: Injecting gas into the battery within a first time range so that the gas pressure in the battery reaches a maximum pressure of a corresponding air injection test; Within a second time range, controlling the gas pressure in the battery to maintain a corresponding maximum pressure; Within a third time range, releasing the gas in the battery so that the gas pressure in the battery returns to the pressure before the gas is injected; In a fourth time range, the gas pressure in the battery is controlled to maintain the pressure before the gas is injected.

3. The method according to claim 2, characterized in that The method of obtaining the number of breaths corresponding to each group of gas injection tests includes: For any set of gas injection tests, during multiple charging and discharging tests of the set of gas injection tests, detecting whether the battery is leaking; If the battery leaks, it is determined that the weld of the battery is cracked, and the number of gas charging and discharging tests performed until the weld of the battery is cracked is recorded as the number of breaths of the gas injection test.

4. The method according to claim 3, characterized in that The fatigue life curve of the weld of the battery in the whole life cycle is obtained based on the breathing number of each group of gas injection tests, including: According to the fatigue strength and breathing number corresponding to each group of gas injection tests, a fatigue life curve of the weld of the battery over the entire life cycle is fitted, wherein the vertical axis of the fatigue life curve is the fatigue strength, and the horizontal axis of the fatigue life curve is the breathing number.

5. The method according to claim 1, characterized in that The method of performing multiple cycles of charge and discharge tests on the battery and obtaining fatigue strength of the corresponding charge and discharge tests includes: Performing multiple cycles of charge and discharge tests on the battery, wherein one cycle of charge and discharge test includes a charging process, a first static process, a discharging process, and a second static process; For any cycle of charge and discharge test, the corresponding fatigue strength is collected and calculated, wherein one cycle of charge and discharge test corresponds to one fatigue strength.

6. The method according to claim 5, characterized in that For any cycle of charge and discharge test, the corresponding fatigue strength is collected and calculated, including: For any cycle of charge and discharge test, during the charge and discharge test, the maximum expansion force and the minimum expansion force on the large surface of the battery are collected through the pressure sensor; Calculating the expansion force difference between the maximum expansion force and the minimum expansion force; The ratio of the expansion force difference to the area of ​​the large surface of the battery is calculated to obtain the actual pressure on the large surface of the battery, and the actual pressure on the large surface of the battery is recorded as the fatigue strength of the battery in this charge and discharge test.

7. The method according to claim 1, characterized in that Determining the reliability of the battery weld according to the fatigue strength of each cycle of charge and discharge test, the fatigue life curve and a preset upper limit of the loss degree includes: For any cycle of the charge-discharge test fatigue strength, the fatigue strength is input into the fatigue life curve to obtain the corresponding breathing number, wherein one fatigue strength corresponds to one breathing number; The reciprocals of the breathing times are accumulated to obtain the fatigue loss degree of the battery weld; If the fatigue loss degree of the battery weld is less than the upper limit of the loss degree, it is determined that the reliability of the battery weld meets the requirement; If the fatigue loss degree of the battery weld is greater than the upper limit of the loss degree, it is determined that the reliability of the battery weld does not meet the requirements.

8. A weld evaluation device, characterized in that: include: Gas injection unit, breathing number acquisition unit, fatigue curve evaluation unit, charge and discharge test unit and reliability evaluation unit; The gas injection unit is used to perform multiple groups of gas injection tests on the battery, wherein the maximum pressure of the gas injected in different groups of air injection tests is different, and the same group includes multiple charging and discharging tests, and the maximum pressure of the gas injected in the multiple charging and discharging tests in the same group is the same; The breathing number obtaining unit is used to obtain the breathing number corresponding to each group of gas injection tests, wherein one group of gas injection tests corresponds to one breathing number, and the breathing number represents the number of charging and discharging tests corresponding to when cracks appear in the battery weld during the group of gas injection tests; The fatigue curve evaluation unit is used to obtain a fatigue life curve of the weld of the battery over the entire life cycle based on the number of breaths of each group of gas injection tests; The charge and discharge test unit is used to perform multiple cycles of charge and discharge tests on the battery and obtain fatigue strength of the corresponding charge and discharge tests, wherein one cycle of charge and discharge tests corresponds to one fatigue strength; The reliability evaluation unit is used to determine the reliability of the battery weld according to the fatigue strength of each cycle of charge and discharge test, the fatigue life curve and a preset upper limit value of the loss degree.

9. A computer-readable storage medium having a program stored thereon, characterized in that: When the program is executed by a processor, the weld evaluation method according to any one of claims 1 to 7 is implemented.

10. An electronic device, characterized in that: The electronic device includes at least one processor, and at least one memory and a bus connected to the processor; wherein the processor and the memory communicate with each other through the bus; the processor is used to call program instructions in the memory to execute the weld evaluation method according to any one of claims 1 to 7.

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