Composite current collector roll welding tooth structure and welding strength optimization method thereof

Abstract

The invention provides a composite current collector roll welding tooth structure and a welding strength optimization method thereof.The welding tooth structure comprises a columnar welding head, three rows of welding teeth are arranged on the columnar surface of the welding head, a first interval is formed between the end faces of the adjacent rows of welding teeth, a second interval is formed between the end faces of each row of welding teeth, the adjacent rows of welding teeth are arranged in a complementary mode, and the first interval is larger than the second interval. The welding teeth are matched with a columnar welding seat during welding; the three rows of welding teeth are arranged in a staggered and complementary mode, so that the force application area for resisting straight pulling when the current collector is subjected to straight pulling force after welding is improved, and then the tensile strength of the current collector after welding is improved.

Description

Technical Field

[0001] The invention relates to the technical field of roll welding teeth, in particular to a composite current collector roll welding tooth structure and a method for optimizing welding strength thereof. Background Art

[0002] In recent years, more and more research has been done on composite current collectors with sandwich structures, which have the function of improving the energy density and safety of lithium batteries. The middle layer of the sandwich structure of the composite current collector is a polymer film with a thickness of several microns. Generally, a metal layer of a certain thickness is plated on both sides of the film by vacuum magnetron sputtering, vacuum evaporation, water electroplating and other processes. When the metal layer is copper, it is generally called composite copper foil, which is used as the negative electrode current collector of lithium batteries. When the metal layer is aluminum, it is generally called composite aluminum foil, which is used as the positive electrode current collector of lithium batteries. When the current collector is used in the battery cell, it is necessary to stack the areas of the multi-layer positive electrode sheet and the multi-layer negative electrode sheet that are not coated with battery materials by ultrasonic welding, and then ultrasonically weld them together with the pole ear to provide a current transmission path for the power load. When the composite current collector is used in the battery cell, due to the presence of the middle polymer film, it is necessary to pre-weld with two layers of conventional current collectors of the same metal material before pre-welding. The composite current collector is sandwiched between the two layers of conventional current collectors, and the three current collectors are stacked and ultrasonically welded. Patent document CN 115275214 A discloses a composite current collector transfer welding method, which can be used for spot welding of sheets by full welding or multi-point welding. The welding points of multi-point welding can be circular or rectangular, and the welding points are arranged in regular columns and rows. With the increasing maturity of the composite current collector coating process, its welding production process in the battery factory has been changed from sheets to coils. In this way, in order to improve production efficiency, the existing technology can realize the transformation from spot welding of coated battery material sheets to roll-to-roll welding of coils. This roll-to-roll welding process is generally called roll welding process. Patent document CN216528958U discloses a composite material roll welding integrated equipment, in which the material roll is set in the middle, and conventional foils are set on the upper and lower sides. After the three-layer superimposed area is aligned by the correction component, it is roll welded by the roll welding machine and then rolled up, that is, the roll welding of the pole piece prepared by the composite current collector is completed. Patent document CN207668689U discloses an ultrasonic roll welding mechanism, which is used to reduce the shaking of the welding head during the roll welding process to improve the welding quality. Patent document CN116060817A discloses a method, device and electronic device for determining the welding quality of a composite current collector. According to the roller position data of a roll welder, the roller impact force data of a roll welder, the roller vibration data of a roll welder, the linear speed data of a roll welder and the linear speed data of front and rear pressure rollers in the composite current collector to be detected, the target data features corresponding to the composite current collector to be detected when welding a target copper foil are determined; the target data features are input into a trained welding quality detection model to determine the target welding quality score of the target copper foil, wherein the trained welding quality detection model is trained based on the historical data features of welding the composite current collector to the historical copper foil; based on the target welding quality score, it is determined whether the welding quality of the composite current collector to the target copper foil is qualified.

[0003] The spot welding process performed by the spot welding head in the prior art solution has low production efficiency, and the rolling welding process can improve welding efficiency and welding quality; from the perspective of welding mechanism, the ultrasonic welding of the composite current collector and the conventional current collector requires the ultrasonic friction to generate heat to squeeze the polymer film in the current collector welding area, and the metals are melted and hot-pressed together. After welding, the composite current collector and the conventional current collector form an integral current collector. The welding process is a process in which the composite current collector is damaged. The tensile strength of the current collector is lower than the tensile strength of the composite current collector itself before welding. This requires the structural design of the welding teeth so that the performance of the current collector after welding is infinitely close to the various properties of the composite current collector before welding. The existing composite current collector welding quality evaluation method records the roller position data of the rolling welding machine, the roller impact force data of the rolling welding machine, the roller vibration data of the rolling welding machine, the linear speed data of the rolling welding machine, and the linear speed data of the front and rear pressure rollers, and compares them with the historical welding data. When the instant parameters are within the historical data range, the welding quality is judged to be intact. No actual measurement is taken from the finished welding product. The welding quality is judged to be acceptable based on the instant welding parameter records that meet the requirements. It is impossible to conduct quantitative evaluation and the actual welding quality cannot be guaranteed. Summary of the invention

[0004] The present invention has two purposes. The first aspect is to provide a composite current collector roll welding weld tooth structure, in which three rows of weld teeth are staggered and complementary to increase the force area resisting straight pulling when subjected to straight pulling force after welding, thereby increasing the tensile strength of the current collector after welding; the second aspect is to provide a welding strength optimization method for a composite current collector roll welding weld tooth structure, firstly, the tensile strength of the composite current collector is measured, which is the upper limit of the tensile strength after welding, and then the current collector after welding is sampled, and the straight pulling force, resistance, and the number of perforations caused by the weld teeth in the sample welding area are used as evaluation indicators. After comparing the standard deviation, the welding quality level is quantitatively evaluated to determine the optimal welding process parameters.

[0005] In order to achieve the first objective, the following technical solutions are proposed: A composite current collector roll welding tooth structure comprises a columnar welding head, wherein three rows of welding teeth are arranged on the cylindrical surface of the welding head, a first spacing is arranged between the end faces of adjacent rows of welding teeth, a second spacing is arranged between the end faces of each row of welding teeth, adjacent rows of welding teeth are arranged complementary, and the welding teeth are matched with a columnar welding seat during welding.

[0006] The present invention includes a columnar welding head and a columnar welding seat, wherein the two sides of the welding head are coaxially connected with a first connecting member and a second connecting member, wherein the first connecting member and the second connecting member are used to connect a fixing device, and the two sides of the welding seat are coaxially connected with a third connecting member and a fourth connecting member, wherein the third connecting member and the fourth connecting member are used to connect an ultrasonic device and a torque applying device, and a welding tooth structure is provided on the cylindrical surface of the welding head, wherein the welding tooth structure is designed in three rows, wherein a first spacing is provided between the end faces of the welding teeth of the rows and rows, and the welding marks formed on the current collector by the end faces of the welding teeth of the adjacent rows are arranged complementary in the welding belt direction, and a second spacing is provided between the end faces of the welding teeth of each row, so as to increase the force application area of ​​the current collector to resist the straight pulling force after welding, thereby improving the tensile strength of the current collector after welding, and the welding teeth are used in combination with the welding seat with a flat cylindrical surface during welding. The three rows of welding teeth of the present invention are staggered and complementary to increase the force application area of ​​the current collector to resist the straight pulling force after welding, thereby improving the tensile strength of the current collector after welding.

[0007] Preferably, the welding tooth is a rectangular protrusion, and the ratio of the side length of the welding tooth along the axial direction of the welding head to the side length of the welding tooth along the radial direction of the welding head is between 0.4 and 0.6.

[0008] The end face of the welding tooth of the present invention is rectangular, the side length along the axial direction of the welding head is L1, and the side length along the radial direction of the welding head is L2, and the two satisfy the relationship: 0.4≤L1 / L2≤0.6, preferably, L1 / L2=0.44.

[0009] Preferably, the side length of the welding teeth along the radial direction of the welding head is between 350 μm and 500 μm. The side length L2 along the radial direction of the welding head of the present invention satisfies 350 μm≤L2≤500 μm.

[0010] Preferably, the second spacing is the same as the side length of the welding teeth along the radial direction of the welding head.

[0011] The distance L4 between the end faces of each row of welding teeth of the welding teeth of the present invention satisfies the relationship: L4=L2.

[0012] Preferably, the first spacing is between 400 μm and 600 μm.

[0013] The distance L3 between adjacent rows of end faces of three rows of welding teeth of the present invention satisfies the relationship: 400 μm≤L3≤600 μm, preferably, L3=500 μm.

[0014] Preferably, the width of the welding seat is between 1.2 times and 1.5 times the total width of the three rows of welding teeth.

[0015] The width L5 of the welding seat used in the present invention satisfies the relationship: 1.2*(3L1+2L3)≤L5≤1.5*(3L1+2L3).

[0016] In order to achieve the second objective, the following technical solutions are proposed: A method for optimizing the welding strength of a composite current collector roll welding tooth structure, using the composite current collector roll welding tooth structure, comprises the following steps: S1, select a certain type of composite aluminum foil A and obtain its physical property information; S2, calculate the straight tension of a certain type of composite aluminum foil A according to the physical property information; S3, setting several groups of welding parameters and performing roll welding on a certain type of composite aluminum foil A; S4, obtaining reference indicators of roll welding samples under different sets of welding parameters; S5, selecting a set of welding parameters with the best reference index as production welding parameters.

[0017] Preferably, the reference indicators include the number of perforations, straight pull force and resistance value.

[0018] Preferably, S5 comprises the following steps: Obtain the standard deviation and average value of the resistance value and the straight pull force, obtain the average value of the number of perforations, and select a set of welding parameters with a small standard deviation of the resistance value and the straight pull force, a large average value of the resistance value and the straight pull force, and a small average value of the number of perforations as production welding parameters.

[0019] Preferably, the physical property information includes thickness and transverse tensile strength.

[0020] The specific steps of the present invention are as follows: S1, take a composite current collector foil W15mm*L20cm size sample and test the thickness T with a Mahr thickness gauge, and test the transverse tensile strength P with a tensile machine; S2, calculate the straight tension of the light foil according to the formula F = PS = PWT, unit N; S3, setting several sets of welding parameters for roll welding; S4, take samples for testing at different welding parameters and record the number of perforations, straight pull force and resistance value of the samples; S5, calculate the average value and standard deviation of the straight pull force and resistance value, and calculate the average value of the number of perforations. The welding quality is better when the average value of the straight pull force and resistance value is large, the standard deviation is small, and the average value of the number of perforations is small, and the corresponding welding parameters are better.

[0021] The beneficial effects of the present invention are as follows: providing a composite current collector roll welding weld tooth structure, wherein three rows of weld teeth are arranged in a staggered and complementary manner to increase the force area for resisting straight pulling when subjected to straight pulling force after welding, thereby increasing the tensile strength of the current collector after welding; providing a welding strength optimization method for a composite current collector roll welding weld tooth structure, firstly measuring the tensile strength of the composite current collector, which is the upper limit of the tensile strength after welding, and then sampling the current collector after welding, using straight pulling force, resistance, and the number of perforations caused by the weld teeth in the welding area of ​​the sample as evaluation indicators, and through standard deviation comparison, quantitatively evaluating the welding quality level, determining the optimal welding process parameters, and improving the welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the weld tooth structure of the composite current collector of the present invention - a front view; Figure 2 It is a partial enlarged schematic diagram of the A region of the roll welding tooth structure of the composite current collector of the present invention; Figure 3 It is a schematic diagram of the right view B of the roll welding tooth structure of the composite current collector of the present invention; Figure 4 It is a schematic diagram of the use state of the composite current collector roll welding welding teeth of the present invention - a side view; Figure 5 It is a schematic diagram of the steps in the method of the present invention; Among them: 1, welding head; 2, welding head; 1.1, first connecting piece; 1.2, second connecting piece; 2.1, third connecting piece; 2.2, fourth connecting piece. DETAILED DESCRIPTION

[0023] Embodiment 1: refer to Figure 1 , Figure 2 , Figure 3 and Figure 4 , Figure 1 The rectangular coordinate system is recorded as (a, r), a is the axial direction of the main view, and r is the radial direction; r1, r2, and r3 are respectively the three rows of welding teeth in the radial r plane; r3, r2, and r1 are respectively the first row of welding teeth, the second row of welding teeth, and the third row of welding teeth when viewed from the right view B direction.

[0024] The present embodiment proposes a composite current collector roll welding weld tooth structure, including a columnar welding head 1 and a columnar welding seat 2, wherein the welding head 1 is coaxially connected with a first connecting member 1.1 and a second connecting member 1.2 on both sides, and the first connecting member 1.1 and the second connecting member 1.2 are used to connect a fixing device, and the welding seat 2 is coaxially connected with a third connecting member 2.1 and a fourth connecting member 2.2 on both sides, and the third connecting member 2.1 and the fourth connecting member 2.2 are used to connect an ultrasonic device and a torque applying device, and a weld tooth structure is provided on the cylindrical surface of the welding head 1, and the weld tooth structure is designed in three rows, and a first spacing is provided between the end faces of the weld teeth of the rows and the weld marks formed on the current collector by the end faces of the weld teeth of adjacent rows are arranged complementary in the welding tape direction, and a second spacing is provided between the end faces of the weld teeth of each row, which is used to increase the force application area of ​​the current collector to resist the straight pulling when it is subjected to straight pulling force after welding, thereby improving the tensile strength of the current collector after welding, and the weld teeth are used in combination with the welding seat 2 whose cylindrical surface is a plane during welding. The three rows of welding teeth of the present invention are arranged in a staggered and complementary manner to increase the force application area for resisting the straight pulling force after welding, thereby increasing the tensile strength of the current collector after welding.

[0025] Embodiment 2: This embodiment optimizes the size of the welding teeth on the basis of the embodiment 1, and proposes a composite current collector rolling welding welding tooth structure, including a columnar welding head 1 and a columnar welding seat 2, the welding head 1 is coaxially connected with a first connecting member 1.1 and a second connecting member 1.2 on both sides, the first connecting member 1.1 and the second connecting member 1.2 are used to connect the fixing device, the welding seat 2 is coaxially connected with a third connecting member 2.1 and a fourth connecting member 2.2 on both sides, the third connecting member 2.1 and the fourth connecting member 2.2 are used to connect the ultrasonic device and the torque applying device, a welding tooth structure is provided on the cylindrical surface of the welding head 1, and the welding tooth structure is designed in three rows, a first spacing is provided between the end faces of the welding teeth of the rows, and the welding marks formed on the current collector by the end faces of the welding teeth of adjacent rows are arranged complementary in the welding tape direction, a second spacing is provided between the end faces of the welding teeth of each row, which is used to increase the force application area of ​​the current collector to resist the straight pulling when it is subjected to the straight pulling force after welding, thereby improving the tensile strength of the current collector after welding, and the welding teeth are used in combination with the welding seat 2 whose cylindrical surface is a plane during welding. The three rows of welding teeth of the present invention are arranged in a staggered and complementary manner to increase the force application area for resisting the straight pulling force after welding, thereby increasing the tensile strength of the current collector after welding.

[0026] The end face of the welding tooth of the present invention is rectangular, the side length along the axial direction of the welding head is L1, and the side length along the radial direction of the welding head is L2, and the two satisfy the relationship: 0.4≤L1 / L2≤0.6 and 350μm≤L2≤500μm, preferably, L1 / L2=0.44.

[0027] The distance L4 between the end faces of each row of welding teeth of the welding teeth of the present invention satisfies the relationship: L4=L2.

[0028] The distance L3 between adjacent rows of end faces of three rows of welding teeth of the present invention satisfies the relationship: 400 μm≤L3≤600 μm, preferably, L3=500 μm.

[0029] The width L5 of the welding seat used in the present invention satisfies the relationship: 1.2*(3L1+2L3)≤L5≤1.5*(3L1+2L3).

[0030] Embodiment 3: This embodiment proposes a method for optimizing the welding strength of a composite current collector roll welding tooth structure based on embodiment 1. Figure 5 , the specific steps are as follows: S1, take a composite current collector foil W15mm*L20cm size sample and test the thickness T with a Mahr thickness gauge, and test the transverse tensile strength P with a tensile machine; S2, calculate the straight tension of the light foil according to the formula F = PS = PWT, unit N; S3, setting several sets of welding parameters for roll welding; S4, take samples for testing at different welding parameters and record the number of perforations, straight pull force and resistance value of the samples; S5, calculate the average value and standard deviation of the straight pull force and resistance value, and calculate the average value of the number of perforations. The welding quality is better when the average value of the straight pull force and resistance value is large, the standard deviation is small, and the average value of the number of perforations is small, and the corresponding welding parameters are better.

[0031] This embodiment is described in detail using 9 test examples and 3 comparative examples.

[0032] Test Example 1: Select composite current collector light foil W15mm*L20cm; refer to Figure 1 The three rows of welding teeth of the welding head 1 are arranged in a complementary manner between adjacent rows. The radial side length L2 of the end face rectangle of the welding tooth along the welding head is 500μm, L1 / L2 is 0.44, that is, L1 is 220μm, and the adjacent spacing L3 between the end faces of the three rows of welding teeth is 500μm.

[0033] The optimization method for the roll welding strength of a certain type of composite aluminum foil A is carried out according to the following steps: The quality evaluation method for the roll welding strength of a certain type of composite aluminum foil A is carried out according to the following steps: S1, composite aluminum foil A is selected as the positive electrode current collector; S2, the basic physical properties of which are shown in Table 1; S3, rolling the composite aluminum foil A after coating and rolling, the rolling welding parameters are: welding speed 7.5m / min, welding pressure 130N, amplitude 12%; S4, take samples of the welded material in succession and number them 1-12, with a sample width of 15 mm, test the tension with a tensile testing machine, and test the resistance with a DC resistance meter. During the resistance test, the positive and negative probes are pressed 7.5 mm away from the welding area, and the number of perforations of each sample is recorded; S5, calculate the average value and standard deviation of the tensile force and resistance sample measurement values, and compare them with the welding indicators of other welding parameter groups. The welding parameter group with a larger average value and a smaller standard deviation is better.

[0034] Test Example 2: The welding pressure in this test example is set to 160N, and other parameters and operation steps are the same as those in test example 1, including the following steps: S1, the composite aluminum foil A is selected as the positive electrode current collector; S2, the basic physical properties of which are shown in Table 1; S3, rolling the composite aluminum foil A after coating and rolling, the rolling welding parameters are: welding speed 7.5m / min, welding pressure 160N, amplitude 12%; S4, take samples of the welded material in succession and number them 1-12, with a sample width of 15 mm, test the tension with a tensile testing machine, and test the resistance with a DC resistance meter. During the resistance test, the positive and negative probes are pressed 7.5 mm away from the welding area, and the number of perforations of each sample is recorded; S5, calculate the average value and standard deviation of the tensile force and resistance sample measurement values, and compare them with the welding indicators of other welding parameter groups. The welding parameter group with a larger average value and a smaller standard deviation is better.

[0035] Test Example 3: The welding pressure in this test example is set to 180N, and other parameters and operation steps are the same as those in Test Example 1, including the following steps: S1, the composite aluminum foil A is selected as the positive electrode current collector; S2, the basic physical properties of which are shown in Table 1; S3, rolling the composite aluminum foil A after coating and rolling, the rolling welding parameters are: welding speed 7.5m / min, welding pressure 180N, amplitude 12%; S4, take samples of the welded material in succession and number them 1-12, with a sample width of 15 mm, test the tension with a tensile testing machine, and test the resistance with a DC resistance meter. During the resistance test, the positive and negative probes are pressed 7.5 mm away from the welding area, and the number of perforations of each sample is recorded; S5, calculate the average value and standard deviation of the tensile force and resistance sample measurement values, and compare them with the welding indicators of other welding parameter groups. The welding parameter group with a larger average value and a smaller standard deviation is better.

[0036] Table 2 shows the welding indicators of Test Example 1, Test Example 2, and Test Example 3.

[0037] Test example 4: The welding speed of this test example is 15m / min, the welding pressure is set to 160N, and the other parameters and operation steps are the same as those of Test Example 1, including the following steps: The following steps are involved: S1, composite aluminum foil A is selected as the positive electrode current collector; S2, the basic physical properties of which are shown in Table 1; S3, rolling the composite aluminum foil A after coating and rolling, the rolling welding parameters are: welding speed 15m / min, welding pressure 160N, amplitude 12%; S4, take samples of the welded material in succession and number them 1-12, with a sample width of 15 mm, test the tension with a tensile testing machine, and test the resistance with a DC resistance meter. During the resistance test, the positive and negative probes are pressed 7.5 mm away from the welding area, and the number of perforations of each sample is recorded; S5, calculate the average value and standard deviation of the tensile force and resistance sample measurement values, and compare them with the welding indicators of other welding parameter groups. The welding parameter group with a larger average value and a smaller standard deviation is better.

[0038] Test Example 5: The welding pressure of this test example is set to 200N, and other parameters and operation steps are the same as those of test example 4, including the following steps: The following steps are involved: S1, composite aluminum foil A is selected as the positive electrode current collector; S2, the basic physical properties of which are shown in Table 1; S3, rolling the composite aluminum foil A after coating and rolling, the rolling welding parameters are: welding speed 15m / min, welding pressure 200N, amplitude 12%; S4, take samples of the welded material in succession and number them 1-12, with a sample width of 15 mm, test the tension with a tensile testing machine, and test the resistance with a DC resistance meter. During the resistance test, the positive and negative probes are pressed 7.5 mm away from the welding area, and the number of perforations of each sample is recorded; S5, calculate the average value and standard deviation of the tensile force and resistance sample measurement values, and compare them with the welding indicators of other welding parameter groups. The welding parameter group with a larger average value and a smaller standard deviation is better.

[0039] Test Example 6: The welding pressure of this test example is set to 300N, and other parameters and operation steps are the same as those of test example 4, including the following steps: The following steps are involved: S1, composite aluminum foil A is selected as the positive electrode current collector; S2, the basic physical properties of which are shown in Table 1; S3, rolling the composite aluminum foil A after coating and rolling, the rolling welding parameters are: welding speed 15m / min, welding pressure 300N, amplitude 12%; S4, take samples of the welded material in succession and number them 1-12, with a sample width of 15 mm, test the tension with a tensile testing machine, and test the resistance with a DC resistance meter. During the resistance test, the positive and negative probes are pressed 7.5 mm away from the welding area, and the number of perforations of each sample is recorded; S5, calculate the average value and standard deviation of the tensile force and resistance sample measurement values, and compare them with the welding indicators of other welding parameter groups. The welding parameter group with a larger average value and a smaller standard deviation is better.

[0040] The welding indicators of Test Examples 4, 5 and 6 are compared in the table.

[0041] Test Example 7: The welding speed of this test example is 30m / min, the welding pressure is set to 300N, and the other parameters and operation steps are the same as those of Test Example 1, including the following steps: S1, the composite aluminum foil A is selected as the positive electrode current collector; S2, the basic physical properties of which are shown in Table 1; S3, rolling the composite aluminum foil A after coating and rolling, the rolling welding parameters are: welding speed 30m / min, welding pressure 300N, amplitude 12%; S4, take samples of the welded material in succession and number them 1-12, with a sample width of 15 mm, test the tension with a tensile testing machine, and test the resistance with a DC resistance meter. During the resistance test, the positive and negative probes are pressed 7.5 mm away from the welding area, and the number of perforations of each sample is recorded; S5, calculate the average value and standard deviation of the tensile force and resistance sample measurement values, and compare them with the welding indicators of other welding parameter groups. The welding parameter group with a larger average value and a smaller standard deviation is better.

[0042] Test Example 8: The welding pressure of this test example is set to 350N, and other parameters and operation steps are the same as those of test example 7, including the following steps: S1, the composite aluminum foil A is selected as the positive electrode current collector; S2, the basic physical properties of which are shown in Table 1; S3, rolling the composite aluminum foil A after coating and rolling, the rolling welding parameters are: welding speed 30m / min, welding pressure 350N, amplitude 12%; S4, take samples of the welded material in succession and number them 1-12, with a sample width of 15 mm, test the tension with a tensile testing machine, and test the resistance with a DC resistance meter. During the resistance test, the positive and negative probes are pressed 7.5 mm away from the welding area, and the number of perforations of each sample is recorded; S5, calculate the average value and standard deviation of the tensile force and resistance sample measurement values, and compare them with the welding indicators of other welding parameter groups. The welding parameter group with a larger average value and a smaller standard deviation is better.

[0043] Test Example 9: The welding pressure of this test example is set to 400N, and other parameters and operation steps are the same as those of test example 7, including the following steps: S1, composite aluminum foil A is selected as the positive electrode current collector; S2, the basic physical properties of which are shown in Table 1; S3, rolling the composite aluminum foil A after coating and rolling, the rolling welding parameters are: welding speed 30m / min, welding pressure 400N, amplitude 12%; S4, take samples of the welded material in succession and number them 1-12, with a sample width of 15 mm, test the tension with a tensile testing machine, and test the resistance with a DC resistance meter. During the resistance test, the positive and negative probes are pressed 7.5 mm away from the welding area, and the number of perforations of each sample is recorded; S5, calculate the average value and standard deviation of the tensile force and resistance sample measurement values, and compare them with the welding indicators of other welding parameter groups. The welding parameter group with a larger average value and a smaller standard deviation is better.

[0044] Table 2 shows the welding indicators of Test Examples 7, 8 and 9.

[0045] Comparative Example 1: The welding teeth of the comparative welding head adopt a conventional alignment arrangement, and other parameters and operation steps are the same as those of Experimental Example 1, including the following steps: S1, composite aluminum foil A is selected as the positive electrode current collector; S2, the basic physical properties of which are shown in Table 1; S3, rolling the composite aluminum foil A after coating and rolling, the rolling welding parameters are: welding speed 7.5m / min, welding pressure 130N, amplitude 12%; S4, take samples of the welded material in succession and number them 1-12, with a sample width of 15 mm, test the tension with a tensile testing machine, and test the resistance with a DC resistance meter. During the resistance test, the positive and negative probes are pressed 7.5 mm away from the welding area, and the number of perforations of each sample is recorded; S5, calculate the average value and standard deviation of the tensile force and resistance sample measurement values, and compare them with the welding indicators of other welding parameter groups. The welding parameter group with a larger average value and a smaller standard deviation is better.

[0046] Comparative Example 2: The welding teeth of the comparative welding head adopt a conventional alignment arrangement, and other parameters and operation steps are the same as those of Experimental Example 4, including the following steps: The following steps are involved: S1, composite aluminum foil A is selected as the positive electrode current collector; S2, the basic physical properties of which are shown in Table 1; S3, rolling the composite aluminum foil A after coating and rolling, the rolling welding parameters are: welding speed 15m / min, welding pressure 160N, amplitude 12%; S4, take samples of the welded material in succession and number them 1-12, with a sample width of 15 mm, test the tension with a tensile testing machine, and test the resistance with a DC resistance meter. During the resistance test, the positive and negative probes are pressed 7.5 mm away from the welding area, and the number of perforations of each sample is recorded; S5, calculate the average value and standard deviation of the tensile force and resistance sample measurement values, and compare them with the welding indicators of other welding parameter groups. The welding parameter group with a larger average value and a smaller standard deviation is better.

[0047] Comparative Example 3: The welding teeth of the comparative welding head adopt a conventional alignment arrangement, and other parameters and operation steps are the same as those of Experimental Example 7, including the following steps: S1, composite aluminum foil A is selected as the positive electrode current collector; S2, the basic physical properties of which are shown in Table 1; S3, rolling the composite aluminum foil A after coating and rolling, the rolling welding parameters are: welding speed 30m / min, welding pressure 300N, amplitude 12%; S4, take samples of the welded material in succession and number them 1-12, with a sample width of 15 mm, test the tension with a tensile testing machine, and test the resistance with a DC resistance meter. During the resistance test, the positive and negative probes are pressed 7.5 mm away from the welding area, and the number of perforations of each sample is recorded; S5, calculate the average value and standard deviation of the tensile force and resistance sample measurement values, and compare them with the welding indicators of other welding parameter groups. The welding parameter group with a larger average value and a smaller standard deviation is better.

[0048] Table 2 is a comparison of welding indicators of different welding parameter groups of the test examples and comparative examples. From the comparison of test example 1 and comparative example 1, it can be seen that under the setting of welding speed 7.5m / min, welding pressure 130N, and amplitude 12%, the welding tension of the complementary arrangement of the new welding teeth of the present invention can be increased by 38.8% relative to the conventional aligned arrangement of welding teeth, and the resistance is lower; from the comparison of test example 4 and comparative example 2, it can be seen that under the setting of welding speed 15m / min, welding pressure 160N, and amplitude 12%, the welding tension of the complementary arrangement of the new welding teeth of the present invention can be increased by 61.0% relative to the conventional aligned arrangement of welding teeth; from the comparison of test example 7 and comparative example 3, it can be seen that under the setting of welding speed 30m / min, welding pressure 350N, and amplitude 12%, the welding tension of the complementary arrangement of the new welding teeth structure of the present invention can be increased by 28.7% relative to the conventional aligned arrangement of welding teeth, that is, the complementary arrangement of the welding teeth of the present invention can significantly increase the welding tension. By comparing Test Examples 1-3, Test Examples 4-6, and Test Examples 7-9, the optimal welding pressure under different welding speeds can be easily obtained. The welding quality evaluation method of the present invention is easy to operate and simple to analyze.

Claims

1. A composite current collector roll welding tooth structure, characterized in that: The invention comprises a columnar welding head (1), wherein three rows of welding teeth are arranged on the cylindrical surface of the welding head (1), a first spacing is arranged between the end faces of the welding teeth in adjacent rows, a second spacing is arranged between the end faces of the welding teeth in each row, the welding teeth in adjacent rows are arranged complementary, and the welding teeth are matched with a columnar welding seat (2) during welding.

2. The composite current collector roll welding tooth structure according to claim 1, characterized in that: The welding tooth is a rectangular protrusion, and the ratio of the side length of the welding tooth along the axial direction of the welding head to the side length of the welding tooth along the radial direction of the welding head is between 0.4 and 0.

6.

3. The composite current collector roll welding tooth structure according to claim 2, characterized in that: The side length of the welding teeth along the radial direction of the welding head is between 350 μm and 500 μm.

4. The composite current collector roll welding tooth structure according to claim 2, characterized in that: The second spacing is the same as the side length of the welding teeth along the radial direction of the welding head.

5. A composite current collector roll welding tooth structure according to any one of claims 1 to 4, characterized in that: The first spacing is between 400 μm and 600 μm.

6. A composite current collector roll welding tooth structure according to any one of claims 1 to 4, characterized in that: The width of the welding seat (2) is between 1.2 and 1.5 times the total width of the three rows of welding teeth.

7. A method for optimizing the welding strength of a composite current collector roll welding tooth structure, using a composite current collector roll welding tooth structure as claimed in claim 1, characterized in that: The following steps are involved: S1, select a certain type of composite aluminum foil A and obtain its physical property information; S2, calculate the straight tension of a certain type of composite aluminum foil A according to the physical property information; S3, setting several groups of welding parameters and performing roll welding on a certain type of composite aluminum foil A; S4, obtaining reference indicators of roll welding samples under different sets of welding parameters; S5, selecting a set of welding parameters with the best reference index as production welding parameters.

8. The method for optimizing the welding strength of a composite current collector roll welding tooth structure according to claim 7, characterized in that: The reference indicators include the number of perforations, straight pull force and resistance value.

9. The method for optimizing the welding strength of a composite current collector roll welding tooth structure according to claim 8, characterized in that: The S5 comprises the following steps: Obtain the standard deviation and average value of the resistance value and the straight pull force, obtain the average value of the number of perforations, and select a set of welding parameters with a small standard deviation of the resistance value and the straight pull force, a large average value of the resistance value and the straight pull force, and a small average value of the number of perforations as production welding parameters.

10. The method for optimizing the welding strength of a composite current collector roll welding tooth structure according to claim 7, characterized in that: The physical property information includes thickness and transverse tensile strength.

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