Y-shaped tab connecting piece, welding method, battery and preparation method

Abstract

The invention provides a Y-shaped tab connecting piece, a welding method, a battery and a preparation method, the Y-shaped tab connecting piece comprises a guide handle and two bifurcation ends, the two bifurcation ends are in the horizontal direction, and the maximum bifurcation distance located on the inner side of the bifurcation is not smaller than the compaction thickness of a tab group of a laminated cell connected with the Y-shaped tab connecting piece. The compaction thickness is used for indicating the thickness and value of a metal layer of a tab group of the laminated cell, the width of the guide handle in the horizontal direction is not less than the compaction thickness, and the length of the guide handle in the vertical direction is determined according to the target effective open area of the tab group and the width of the tab group in the horizontal direction; the target effective overcurrent area is determined according to the maximum current required by the battery and the current density of the tab material.

Description

Technical Field

[0001] The present application relates to the technical field of battery preparation, and in particular to a Y-shaped tab connector, a welding method, a battery and a preparation method. Background Art

[0002] In order to meet the energy demand, it is necessary to stack the positive pole pieces, separators, and negative pole pieces of the single cell in parallel by lamination, winding, etc., and lead out the pole lug group from the current collector. The pole lug group is connected together with the metal guide handle or metal connecting piece by welding, so that the pole lug groups welded by each single cell can be connected in series or in parallel to prepare a battery that meets the energy demand. Generally, welding methods include ultrasonic, resistance welding, laser welding, etc., and the welding effect directly affects the overcurrent design and power usage of the cell. The stacking overlap of the pole lug group will affect the size of the effective overlap area, and the effective overlap area will further affect the welding effect. Due to engineering manufacturing tolerances, the stacking overlap will be less than or equal to 100%, affecting the welding accuracy and consistency.

[0003] The welding joints between the tab group and the metal guide handle or metal connecting piece can be welded by flat welding, cladding welding, and bending welding. Flat welding is the simplest but prone to cold welding. Cladding welding and bending welding are not prone to cold welding but have high requirements for equipment, resulting in high process costs. If there are welding defects such as cold welding and missing welding during the welding process, since the in-situ cured polymer battery cells usually have gas discharged during use, the welding points of the tab group will be wetted by the electrolyte. The high-temperature curing step in the battery preparation process will continue to produce gas and cause the electrolyte in the battery to expand and contract, further amplifying the welding defects. Summary of the invention

[0004] In view of this, the purpose of the present application is to provide at least a Y-shaped pole lug connecting piece, a welding method, a battery and a preparation method. By designing a Y-shaped pole lug connecting piece, the inner side of the fork of the Y-shaped pole lug connecting piece is used to connect the pole lug group of the stacked battery cell, and the maximum fork distance on the inner side of the fork should not be less than the metal layer thickness and value of the pole lug group of the stacked battery cell, and the target effective flow area is determined according to the maximum current required by the battery and the current density of the pole lug material, and then the length of the guide handle in the vertical direction is determined by the target effective flow area and the width of the pole lug group, which solves the technical problem in the prior art that the pole lug group of the battery cell is prone to welding defects such as missing welding and leaking welding, and achieves the technical effect of improving the welding quality by connecting the pole lug group through the Y-shaped pole lug connecting piece.

[0005] This application mainly includes the following aspects: In the first aspect, an embodiment of the present application provides a Y-shaped tab connecting piece, wherein the Y-shaped tab connecting piece includes a guide handle and two forked ends, wherein the maximum fork distance of the two forked ends in the horizontal direction and located on the inner side of the fork is not less than the compacted thickness of the tab group of the stacked battery cell connected to the Y-shaped tab connecting piece, and the compacted thickness is used to indicate the metal layer thickness and value of the tab group of the stacked battery cell, the guide handle width of the guide handle in the horizontal direction is not less than the compacted thickness, and the length of the guide handle in the vertical direction is determined based on the target effective current flow area of ​​the tab group and the width of the tab group in the horizontal direction, and the target effective current flow area is determined according to the maximum current required by the battery and the current density of the tab material.

[0006] Optionally, the guide handle width is the sum of widths corresponding to two forked ends, and / or the maximum fork distance is not less than the cell thickness of the laminated cell in the horizontal direction.

[0007] In the second aspect, an embodiment of the present application also provides a welding method for a Y-shaped pole lug connecting sheet, the method comprising: placing a stacked battery cell between an upper welding head and a lower welding head arranged opposite to each other on an ultrasonic welding machine, and controlling a preset welding area of ​​the pole lug group of the stacked battery cell to be located in an overlapping area where the upper welding head maps to the lower welding head; when the horizontal direction of the two forked ends of the Y-shaped pole lug connecting sheet is parallel to the thickness direction of the stacked battery cell, controlling the inner sides of the forks of the two forked ends of the Y-shaped pole lug connecting sheet to be close to the pole lug group of the stacked battery cell, so that the two forked ends gather the pole lug group of the stacked battery cell; starting the ultrasonic welding machine to move the upper welding head and the lower welding head toward each other, and welding the two forked ends of the Y-shaped pole lug connecting sheet to the pole lug group; wherein, the Y-shaped pole lug connecting sheet is the Y-shaped pole lug connecting sheet described in the first aspect or any possible embodiment of the first aspect.

[0008] Optionally, the method further includes: pre-welding the tab group; and welding two forked ends of the Y-shaped tab connecting piece to the pre-welded tab group.

[0009] Optionally, after pre-welding the tab group, the method further comprises: neatly cutting a target end of the tab group after pre-welding, the target end being an end of the tab group close to the two bifurcated ends.

[0010] Optionally, before controlling the inner sides of the two forked ends of the Y-shaped tab connector to approach the tab group of the laminated battery cell, the method further comprises: neatly cutting the target end of the tab group, the target end being one end of the tab group close to the two forked ends.

[0011] In the third aspect, an embodiment of the present application further provides a battery, comprising a battery case, an electrolyte and a battery cell, wherein the battery cell comprises a Y-shaped pole tab connecting piece and a stacked battery cell, wherein the Y-shaped pole tab connecting piece is connected to a pole tab group of the stacked battery cell by welding, wherein the Y-shaped pole tab connecting piece is the Y-shaped pole tab connecting piece described in the first aspect or any possible embodiment of the first aspect.

[0012] Optionally, the tab group of the laminated battery cell includes a positive tab group and a negative tab group, and the Y-shaped tab connecting piece includes a positive Y-shaped tab connecting piece welded to the positive tab group and a negative Y-shaped tab connecting piece welded to the negative tab group.

[0013] Optionally, the battery includes a plurality of battery cells, and the battery includes at least one battery cell group, the number of battery cells in each battery cell group is the same, and the battery cell groups are connected in series or in parallel according to battery capacity requirements, wherein the battery cells in each battery cell group are connected in series or in parallel with the positive Y-type pole tab connecting piece and the negative Y-type pole tab connecting piece according to the battery cell group capacity requirements.

[0014] In the fourth aspect, an embodiment of the present application also provides a method for preparing a battery, wherein the battery comprises a battery case, an electrolyte and a battery cell, the battery cell comprises a Y-shaped pole tab connecting piece and a stacked battery cell, the Y-shaped pole tab connecting piece is connected to the pole tab group of the stacked battery cell by welding, the Y-shaped pole tab connecting piece is the Y-shaped pole tab connecting piece described in the first aspect or any possible embodiment of the first aspect, wherein the method comprises: after placing the battery cell and the electrolyte in the battery case, curing the battery according to a preset curing temperature; after performing a vacuum degassing operation on the cured battery according to a preset vacuum pressure, packaging the battery.

[0015] The embodiments of the present application provide a Y-shaped pole tab connecting piece, a welding method, a battery and a preparation method, wherein the Y-shaped pole tab connecting piece comprises a guide handle and two forked ends, wherein the maximum forked distance of the two forked ends in the horizontal direction and located on the inner side of the fork is not less than the compacted thickness of the pole tab group of the laminated battery cell connected to the Y-shaped pole tab connecting piece, and the compacted thickness is used to indicate the metal layer thickness and value of the pole tab group of the laminated battery cell, the guide handle width of the guide handle in the horizontal direction is not less than the compacted thickness, and the length of the guide handle in the vertical direction is determined based on the target effective flow area of ​​the pole tab group and the width of the pole tab group in the horizontal direction, and the target effective flow area is determined according to the maximum current required by the battery and the current density of the pole tab material. By designing a Y-shaped pole lug connecting piece, the inner side of the fork of the Y-shaped pole lug connecting piece is used to connect the pole lug group of the stacked battery cell, the maximum fork distance on the inner side of the fork should not be less than the metal layer thickness and value of the pole lug group of the stacked battery cell, and the target effective flow area is determined according to the maximum current required by the battery and the current density of the pole lug material, and the length of the guide handle in the vertical direction is determined by the target effective flow area and the width of the pole lug group, which solves the technical problem that the pole lug group of the battery cell is prone to welding defects such as missing welding and leaking welding in the prior art, and achieves the technical effect of improving the welding quality by connecting the pole lug group through the Y-shaped pole lug connecting piece.

[0016] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic structural diagram of a Y-shaped tab connecting piece provided in an embodiment of the present application is shown.

[0019] Figure 2 A flow chart of a welding method for a Y-shaped tab connecting piece provided in an embodiment of the present application is shown.

[0020] Figure 3 Schematic diagram showing a Y-shaped tab connecting piece welded to a tab group provided in an embodiment of the present application Figure 1 .

[0021] Figure 4 Schematic diagram showing a Y-shaped tab connecting piece welded to a tab group provided in an embodiment of the present application Figure 2 .

[0022] Figure 5 Schematic diagram showing a Y-shaped tab connecting piece welded to a tab group provided in an embodiment of the present application Figure 3 .

[0023] Figure 6 Schematic diagram showing a Y-shaped tab connecting piece welded to a tab group provided in an embodiment of the present application Figure 4 .

[0024] Figure 7 The schematic diagram of the common guide handle welding pole lug group provided in the embodiment of the present application is shown. Figure 1 .

[0025] Figure 8 The schematic diagram of the common guide handle welding pole lug group provided in the embodiment of the present application is shown. Figure 2 . DETAILED DESCRIPTION

[0026] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of explanation and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn in real proportion. The flowchart used in this application shows the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowchart can be implemented out of sequence, and the steps without logical context can be reversed in order or implemented simultaneously. In addition, those skilled in the art, under the guidance of the content of the present application, can add one or more other operations to the flowchart, or remove one or more operations from the flowchart.

[0027] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0028] At present, lithium-ion batteries are widely used in 3C, energy storage, power batteries and other fields due to their high specific energy, long service life and high rate. However, with the increase of battery energy density and the increase of single cell capacity, battery safety issues are becoming increasingly serious. With the development of battery technology, solid-state batteries are considered to be an important direction for solving battery safety issues. In order to meet energy requirements, it is necessary to stack the positive pole pieces, diaphragms and negative pole pieces of the single cell in parallel by lamination, winding and other methods, and lead out the pole ear group from the current collector. The pole ear group is connected with the metal guide handle or metal connecting piece by welding, so as to prepare a battery that meets energy requirements by connecting the pole ear groups welded by each single cell in series or in parallel. The welding methods mainly include ultrasonic, resistance welding, laser welding and other methods. The welding effect directly affects the overcurrent design and power usage of the battery cell. The stacking overlap of the pole ear group will affect the size of the effective overlap area, and the effective overlap area will further affect the welding effect. Due to engineering manufacturing tolerances, the stacking overlap will be less than or equal to 100%, affecting the welding accuracy and consistency. In-situ cured polymer batteries are preferred in related fields due to their simple process and low battery interface impedance. However, in-situ curing is usually accompanied by gas production. After the welding points of the tab group are wetted by the electrolyte, the high-temperature curing process further amplifies the welding defects due to gas production and thermal expansion and contraction.

[0029] The welding joints between the tab group and the metal guide handle or metal connecting piece can be welded by flat welding, cladding welding, and bending welding. Flat welding is the simplest but prone to cold welding. Cladding welding and bending welding are not prone to cold welding but have high requirements for equipment, resulting in high process costs. If there are welding defects such as cold welding and missing welding during the welding process, since the in-situ cured polymer battery cells usually have gas discharged during use, the welding points of the tab group will be wetted by the electrolyte. The high-temperature curing step in the battery preparation process will continue to produce gas and cause the electrolyte in the battery to expand and contract, further amplifying the welding defects. In the prior art, a metal protective sheet is added to the back side of the electrode foil of the battery cell to improve the cold solder joint of the tab welding; or, a metal sheet is added to increase the welding energy process range to effectively improve the cold solder joint problem, but the addition of the metal protective sheet increases the weight of the welded tab group, increases the material cost and automation cost of the welding process and reduces the battery energy density; or, a protective sheet is added by bending 180 degrees to reduce the welding feeding process, but the protective sheet needs to be bent from 0 degrees horizontally to 180 degrees, which requires the welding machine to add a complex bending mechanism, and is prone to metal fatigue fracture problems, and the automation cost is high and the battery energy density is low.

[0030] Based on this, the embodiment of the present application provides a Y-shaped pole ear connecting piece, a welding method, a battery and a preparation method. By designing a Y-shaped pole ear connecting piece, the inner side of the fork of the Y-shaped pole ear connecting piece is used to connect the pole ear group of the laminated battery cell, and the maximum fork distance inside the fork should be no less than the metal layer thickness and value of the pole ear group of the laminated battery cell, and the target effective flow area is determined according to the maximum current required by the battery and the current density of the pole ear material, and then the length of the guide handle in the vertical direction is determined by the target effective flow area and the width of the pole ear group, which solves the technical problem that the pole ear group of the battery cell in the prior art is prone to welding defects such as lack of welding and leakage welding, and achieves the technical effect of improving the welding quality by connecting the pole ear group by the Y-shaped pole ear connecting piece, which is specifically as follows: See also Figure 1 , Figure 1 This is a schematic diagram of the structure of a Y-shaped tab connector provided in an embodiment of the present application. Figure 1 As shown, the Y-type pole lug connecting piece provided in the embodiment of the present application includes a guide handle A and two forked ends B, wherein the maximum fork distance d1 of the two forked ends in the horizontal direction and located on the inner side of the fork is not less than the compacted thickness of the pole lug group D of the laminated battery cell C connected by the Y-type pole lug connecting piece, and the compacted thickness is used to indicate the metal layer thickness and value of the pole lug group of the laminated battery cell, where the metal layer thickness of the pole lug group refers to the metal layer thickness and value of each pole lug, the metal layer of the positive pole lug is generally aluminum material, and the metal layer of the negative pole lug is generally nickel material or copper-plated nickel material, the guide handle width of the guide handle in the horizontal direction is not less than the compacted thickness, and the length h of the guide handle in the vertical direction is determined based on the target effective flow area of ​​the pole lug group and the width of the pole lug group in the horizontal direction, and the target effective flow area is determined according to the maximum current required by the battery and the current density of the pole lug material.

[0031] Among them, the stacked battery cell includes multiple positive electrode sheets and multiple negative electrode sheets stacked crosswise, and a coating is inserted between adjacent positive electrode sheets and negative electrode sheets to isolate the positive electrode sheets and the negative electrode sheets. Positive electrode tabs are provided on the positive electrode sheets, and negative electrode tabs are provided on the negative electrode sheets. After the electrode sheets are stacked, the positive electrode tabs of the multiple positive electrode sheets serve as a positive electrode tab group, and the negative electrode tabs of the multiple negative electrode sheets serve as a negative electrode tab group.

[0032] That is to say, both the positive electrode tab group and the negative electrode tab group can be connected through the Y-shaped tab connecting piece.

[0033] like Figure 1As shown, the stacking direction of the tab group or the stacking direction of the tabs of the battery cell is taken as the horizontal direction (x-axis), and the direction perpendicular to the horizontal direction on the plane where the Y-shaped tab connecting piece is located is taken as the vertical direction (y-axis). The guide handle portion B of the Y-shaped tab connecting piece includes two forked ends (B1 and B2), and illustratively, the two forked ends are symmetrically arranged on both sides of the center line of the Y-shaped tab connecting piece in the vertical direction.

[0034] Among them, the cell thickness of the stacked battery cell in the horizontal direction can be understood as the thickness after multiple positive electrodes, multiple coatings and multiple negative electrodes are stacked in sequence, the sum of the metal layer thickness of the tab group can be understood as the sum of the metal layer thickness of each tab in the tab group, and the cell thickness is greater than the sum of the metal layer thickness of the tab group. In other words, the compacted thickness refers to the thickness after the metal layer of each tab in the tab group is compacted. Furthermore, in order for the tab group to be welded to the inner side of the fork of the two forked ends of the Y-shaped tab connecting piece, the maximum fork distance d1 on the inner side of the fork should be greater than or equal to the compacted thickness of the tab group of the stacked battery cell. Among them, the inner side of the fork refers to the side where the two forked ends meet, and the inner side of the fork is located on the side of the Y-shaped tab connecting piece away from the guide handle, that is Figure 1 The position indicated by the blue line in .

[0035] Moreover, the guide handle width d2 in the horizontal direction should be no less than the compacted thickness, so that after the subsequent welding of the pole lug group and the two forked ends of the Y-shaped pole lug connecting plate, the guide handle width is no less than the width of the pole lug group in the horizontal direction, and the target effective flow area of ​​the pole lug group will not be reduced due to welding.

[0036] Exemplarily, the length of the guide handle in the vertical direction is determined by: determining the target effective flow area according to the maximum current required by the battery and the current density of the tab material; determining the length of the guide handle in the vertical direction according to the target effective flow area and the width of the tab group in the horizontal direction.

[0037] Specifically, the target effective flow area of ​​the tab group is calculated according to the ratio of the maximum current required by the battery subsequently packaged into the battery cell and the current density of the tab material. The metal materials used in the positive tab group and the negative tab group are different, so the current densities corresponding to the positive tab group and the negative tab group are also different. Therefore, the target effective flow areas corresponding to the positive tab group and the negative tab group are also different. The current density of the tab material can be found in the power engineering manual. After determining the target effective flow area, the ratio of the target effective flow area to the width of the tab group in the horizontal direction is used as the length of the guide handle in the vertical direction, and this length is the minimum length of the guide handle, so that the area of ​​the guide handle part is not less than the target effective flow area, ensuring that the battery cell can meet the maximum current required by the battery.

[0038] Wherein, the guide handle width is the sum of the widths corresponding to the two forked ends respectively, and / or the maximum fork distance is not less than the cell thickness of the laminated cell in the horizontal direction.

[0039] For example, Figure 1 As shown, the sum of the width d3 of the forked end B1 and the width d4 of the forked end B2 of the two forked ends is equal to the guide handle width d2. Since the current passes through the forked end B1 and the forked end B2 in parallel and then merges to the guide handle, the cross-sectional area of ​​the flow cannot be reduced after the merger, but there is no need to set an excessively large cross-sectional area of ​​the flow, which will cause unnecessary weight increase. Therefore, the guide handle width is set equal to the sum of the widths of the two forked ends. In addition, the maximum bifurcation distance should be greater than or equal to the cell thickness of the laminated cell C in the horizontal direction. In the subsequent welding process, when the pole ear connecting piece moves closer to the pole ear group, it helps that the bifurcation between the two forked ends can automatically gather the pole ear group. Exemplarily, the width d3 of the forked end B1 and the width d4 of the forked end B2 are set to 200 microns, the guide handle width d2 is 400 μm, the length d5 ​​of the forked end is 8 millimeters, and the maximum bifurcation distance is 12 mm.

[0040] Among them, since the ultrasonic welding machine is generally a point welding, an effective current flow area is provided by connecting multiple points in parallel, and the welding is to connect the pole ear and the guide handle in the vertical direction, and the current transmission path is Z-shaped, when the width of the pole ear group is constant, more welds are added by increasing the length of the forked end. At the same time, combined with the engineering equipment process and the actual battery structure size, the length of the forked end is generally set at about 10 mm, and 8 mm is selected in the embodiment of the present application.

[0041] Based on the same application concept, a welding method corresponding to the Y-type pole ear connecting piece provided in the above embodiment is also provided in the embodiment of the present application. Since the principle of solving the problem by the welding method in the embodiment of the present application is similar to that of the Y-type pole ear connecting piece in the above embodiment of the present application, the implementation of the welding method can refer to the implementation of the method, and the repeated parts will not be repeated.

[0042] See also Figure 2 , Figure 2 A flowchart of a welding method for a Y-shaped tab connector provided in an embodiment of the present application. The welding method for a Y-shaped tab connector provided in an embodiment of the present application, wherein the Y-shaped tab connector is a Y-shaped tab connector as described in any of the above embodiments, comprises: S101: placing the laminated battery core between an upper welding head and a lower welding head disposed opposite to each other on an ultrasonic welding machine, and controlling a preset welding area of ​​a tab group of the laminated battery core to be located in an overlapping area mapped from the upper welding head to the lower welding head.

[0043] See also Figure 3 , Figure 3Schematic diagram of a Y-shaped tab connecting piece welded to a tab group provided in an embodiment of the present application Figure 1 .like Figure 3 As shown, an upper welding head E1 and a lower welding head E2 are arranged facing each other on the ultrasonic welding machine, and during the welding process, the distance between the upper welding head and the lower welding head in the horizontal direction is gradually shortened, so as to achieve the welding between the Y-shaped tab connecting sheet and the tab group.

[0044] Among them, the preset welding area refers to the area to be welded on the upper pole ear group, and it should be ensured that the preset welding area can be covered after the distance between the upper welding head and the lower welding head in the horizontal direction is gradually shortened. Therefore, the overlapping area obtained by projecting the upper welding head to the lower welding head along the horizontal direction should at least cover the preset welding area.

[0045] S102: When the horizontal direction of the two forked ends of the Y-shaped tab connecting sheet is parallel to the thickness direction of the laminated battery cell, the inner sides of the forks of the two forked ends of the Y-shaped tab connecting sheet are controlled to be close to the tab group of the laminated battery cell so that the two forked ends gather the tab group of the laminated battery cell.

[0046] That is to say, the horizontal direction of the two forked ends of the Y-shaped pole ear connecting piece is controlled to be parallel to the overlapping direction of the pole pieces in the laminated battery cell. At this time, the Y-shaped pole ear connecting piece and the pole ear group are controlled to move toward each other, or in other words, the distance between the Y-shaped pole ear connecting piece and the pole ear group in the vertical direction is controlled to gradually shorten. Exemplarily, the intersection of the two forked ends in the Y-shaped pole ear connecting piece on the inner side of the fork should be aligned with the center of the thickness of the battery cell of the laminated battery cell, so that the two forked ends can better gather the pole ear group, that is, it is only necessary to control the Y-shaped pole ear connecting piece and the pole ear group to move toward each other, and set the maximum fork distance to be not less than the battery cell thickness, then no other operations are required to gather the pole ear group, and the pole ear group can be automatically gathered during the movement.

[0047] S103: starting the ultrasonic welding machine to move the upper welding head and the lower welding head toward each other, and welding the two forked ends of the Y-shaped tab connecting piece to the tab group.

[0048] That is to say, after the two forked ends of the Y-shaped pole ear connecting piece gather the pole ear group, the upper welding head and the lower welding head of the ultrasonic welding machine can be controlled to start moving toward each other, and the upper welding head and the lower welding head are closed to complete the welding, and then the pole ear side of the stacked battery cell is connected to the Y-shaped pole ear connecting piece.

[0049] Wherein, the method further includes: pre-welding the tab group; welding the two forked ends of the Y-shaped tab connecting piece to the tab group after the pre-welding.

[0050] That is to say, the tab group can also be pre-welded with low energy in advance, and then the pre-welded tab group and the two forked ends of the Y-shaped tab connecting piece can be welded to prevent the tab group from failing to gather and causing the Y-shaped tab connecting piece to be effectively welded. Since the tab metal foil of the battery cell is thin, the pre-welded part needs to control the welding energy to be low. The low-energy pre-welding here is also performed by an ultrasonic welding machine, and other welding methods can also be selected, which is not limited in this application.

[0051] See also Figure 4 , Figure 4 Schematic diagram of a Y-shaped tab connecting piece welded to a tab group provided in an embodiment of the present application Figure 2 .like Figure 4 As shown, after pre-welding the tab group of the stacked battery cell, the pre-weld end D1 of the tab group is obtained, the tab group with the pre-weld end D1 and the two forked ends of the Y-shaped tab connecting piece are moved toward each other in the vertical direction, and the pre-weld end D1 of the tab group and the two forked ends of the Y-shaped tab connecting piece are welded by the upper welding head and the lower welding head.

[0052] After pre-welding the tab group, the method further comprises: neatly cutting the target end of the tab group after pre-welding, wherein the target end is an end of the tab group close to the two bifurcated ends.

[0053] That is to say, one end of the tab group is used to connect the electrode sheet, and the other end of the tab group is the end that needs to be welded to the Y-shaped tab connecting sheet, that is, the end close to the two forked ends of the Y-shaped tab connecting sheet.

[0054] See also Figure 5 , Figure 5 Schematic diagram of a Y-shaped tab connecting piece welded to a tab group provided in an embodiment of the present application Figure 3 .like Figure 5 As shown, after the tab group of the laminated battery cell is pre-welded, the pre-welded end D1 of the tab group is trimmed to obtain the trimmed end D2 to be welded, the tab group with the end D2 to be welded and the two forked ends of the Y-shaped tab connecting piece are moved toward each other in the vertical direction, and the end D2 to be welded of the tab group is welded to the two forked ends of the Y-shaped tab connecting piece by the upper welding head and the lower welding head.

[0055] Among them, cutting the pre-weld end D1 of the tab group can pre-cut the part to be welded neatly, especially for thicker battery cells (such as bare battery cells greater than 10mm). After the multiple layers of tabs are stacked, they gather toward the middle, which will cause the front end of the tab group to form a slope. Subsequent welding may cause incomplete welds in the front row, and only welding the middle tab group will cause poor contact of some tabs. Therefore, it is necessary to cut the pre-weld end D1 of the tab group to obtain a neat end D2 to be welded.

[0056] Before controlling the inner sides of the two forked ends of the Y-shaped tab connector to approach the tab group of the laminated battery cell, the method further includes: neatly cutting the target end of the tab group, the target end being one end of the tab group close to the two forked ends.

[0057] That is to say, it is also possible to directly cut the pole lug group without pre-welding, and then move the cut pole lug group and the two forked ends of the Y-shaped pole lug connecting piece toward each other in the vertical direction, and weld the cut pole lug group and the two forked ends of the Y-shaped pole lug connecting piece through the upper welding head and the lower welding head.

[0058] See also Figure 6 , Figure 6 Schematic diagram of a Y-shaped tab connecting piece welded to a tab group provided in an embodiment of the present application Figure 4 .like Figure 6 As shown, after the Y-shaped tab connector is welded to the tab group, the guide handle portion of the Y-shaped tab connector should have at least an area where the tab group is not welded. This area is used to connect multiple tab groups in series or in parallel, and should not be less than the target effective overcurrent area. In other words, the guide handle portion will be used for welding in series or in parallel at the cell level later, so when welding the tab groups of a cell together, the guide handle portion should be kept from being welded to the tab group.

[0059] Based on the same application concept, a battery corresponding to the Y-shaped pole ear connecting piece provided in the above embodiment is also provided in the embodiment of the present application. Since the principle of solving the problem by the battery in the embodiment of the present application is similar to that of the Y-shaped pole ear connecting piece in the above embodiment of the present application, the implementation of the battery can refer to the implementation of the method, and the repeated parts will not be repeated.

[0060] A battery provided in an embodiment of the present application includes a battery case, an electrolyte and a battery cell, wherein the battery cell includes a Y-shaped pole tab connecting piece and a stacked battery cell, wherein the Y-shaped pole tab connecting piece is connected to a pole tab group of the stacked battery cell by welding, wherein the Y-shaped pole tab connecting piece is a Y-shaped pole tab connecting piece as described in any of the above embodiments.

[0061] Among them, the tab group of the laminated battery cell includes a positive tab group and a negative tab group, and the Y-shaped tab connecting piece includes a positive Y-shaped tab connecting piece welded to the positive tab group and a negative Y-shaped tab connecting piece welded to the negative tab group.

[0062] That is to say, the electrolyte and the battery cell are placed in the battery shell, and the battery cell includes a Y-shaped tab connecting piece and a stacked battery cell welded thereto. The tab group of the stacked battery cell includes a positive tab group and a negative tab group, and the Y-shaped tab connecting piece includes a positive Y-shaped tab connecting piece and a negative Y-shaped tab connecting piece. The positive tab group of the stacked battery cell is welded with a positive Y-shaped tab connecting piece, and the negative tab group of the stacked battery cell is welded with a negative Y-shaped tab connecting piece.

[0063] Wherein, the battery includes multiple cells, and the battery includes at least one cell group, the number of cells in each cell group is the same, and the cell groups are connected in series or in parallel according to the battery capacity requirements, wherein the cells in each cell group are connected in series or in parallel with the positive Y-type pole ear connecting piece and the negative Y-type pole ear connecting piece according to the cell group capacity requirements.

[0064] That is to say, multiple battery cells are arranged in the battery casing, and the multiple battery cells are divided into at least one battery cell group. If there is only one battery cell group, the multiple battery cells in the battery cell group are connected in series or in parallel through the positive Y-type pole ear connecting piece and the negative Y-type pole ear connecting piece. If there are multiple battery cell groups, the multiple battery cell groups can be connected in series or in parallel, and the multiple battery cells in each battery cell group are connected in series or in parallel through the positive Y-type pole ear connecting piece and the negative Y-type pole ear connecting piece. After the multiple battery cells of a battery cell group are connected in series or in parallel, the multiple battery cell groups are connected in series or in parallel through the positive electrode of the battery cell and the negative electrode of the battery cell.

[0065] Based on the same application concept, the embodiments of the present application also provide a method for preparing a battery corresponding to the Y-shaped pole ear connecting piece provided in the above embodiments. Since the principle of solving the problem by the method for preparing the battery in the embodiments of the present application is similar to that of the Y-shaped pole ear connecting piece in the above embodiments of the present application, the implementation of the method for preparing the battery can refer to the implementation of the method, and the repeated parts will not be repeated.

[0066] A method for preparing a battery is also provided in an embodiment of the present application, wherein the battery comprises a battery housing, an electrolyte and a battery cell, wherein the battery cell comprises a Y-shaped pole tab connecting piece and a stacked battery cell, wherein the Y-shaped pole tab connecting piece is connected to a pole tab group of the stacked battery cell by welding, and the Y-shaped pole tab connecting piece is a Y-shaped pole tab connecting piece as described in any of the above embodiments, wherein the method comprises: after placing the battery cell and the electrolyte in the battery housing, curing the battery at a preset curing temperature; after performing a vacuum degassing operation on the cured battery at a preset vacuum pressure, packaging the battery.

[0067] Specifically, after welding the tab group and the Y-type tab connecting piece of the stacked battery cell, the welded battery cell is placed in a battery shell, and then the electrolyte is injected into the battery shell, and the electrolyte injection ratio is 2 g / Ah (gram / ampere-hour). The battery after the electrolyte injection is subjected to high-temperature curing at a preset curing temperature (generally 75°C) for 4 hours, and the battery shell is evacuated to control the battery shell to a vacuum environment to remove the gas in the battery shell, and then the battery is charged and discharged at 0.1C, and finally the battery is packaged.

[0068] For example, multiple batteries can be produced by changing the design specifications of the tab connector to determine the specifications of the tab connector with the best battery quality and the lowest cost. Table 1 is a process parameter table of batteries made by designing tab connectors under different variable conditions.

[0069] Table 1:

[0070] Exemplarily, after the battery is prepared and packaged, the internal resistance of the battery can be tested by an internal resistance meter. It is also possible to charge three parallel samples at a constant current and constant voltage of 3C, and compare the differences by calculating the charging constant current ratio. During the charging process, charge to the charging cut-off voltage, record the charging capacity Q1, and then automatically reduce the charging current through the charging device control to continue charging until the charging current is reduced to a specified value, then the charging is completed and the charging capacity Q2 is recorded, and Q1 / (Q1+Q2) is specified as the charging constant current ratio. The defective rate of the battery can also be tested, and multiple batteries are produced. After each battery is welded, X-ray detection is automatically used to determine the virtual welding and over-welding, and the production data is statistically obtained to obtain the defective rate. The process cost is estimated according to the operation time, and one more process takes longer and costs more. The weight of the pole ear is calculated based on the change in the total mass after molding. The shape of the pole ear connecting piece changes but the weight remains unchanged. Adding a protective sheet increases the weight of the welding process by 50%, and two pieces increase by 100%.

[0071] That is to say, embodiments 1 to 8 all use Y-shaped pole ear connecting pieces to connect the pole ear groups. Embodiments 1 to 6 are based on the premise that the width of the forked end B1 and the width of the forked end B2 divide the guide handle width in half, and the size of the Y-shaped pole ear connecting piece is changed by changing the relationship between the maximum fork distance d1 of the two forked ends in the horizontal direction and located on the inner side of the fork and the compaction thickness. Embodiments 7 to 8 are based on the premise that the maximum fork distance d1 of the two forked ends in the horizontal direction and located on the inner side of the fork is equal to the compaction thickness, and the size of the Y-shaped pole ear connecting piece is changed by setting the width of the forked end B1 and the width of the forked end B2 not to divide the guide handle width in half. Specifically, the energy of the upper welding head on the ultrasonic trigger side is more stable, and the energy of the lower welding head on the receiving side is relatively weak and unstable, and then when the widths of the two forked ends are different, different effects may be caused on the defects in the welding thickness direction of the multi-layer. Furthermore, the upper welding head should generally be close to the wider side of the forked end, that is, in the welding process of Example 7, the forked end B1 is the end close to the upper welding head, and in the welding process of Example 8, the forked end B2 is the end close to the upper welding head. The forked end close to the upper welding head can be changed by flipping the Y-shaped pole ear connecting piece during welding.

[0072] Among them, in Comparative Examples 1 to 5, only a common guide handle is set to weld the tab group, that is, the bifurcated end of the Y-shaped tab connecting piece is removed and only the common guide handle part is retained, and the common guide handle is welded to the tab group, and the upper welding head and the lower welding head are selected separately for welding. Among them, Comparative Example 4 is to set a metal protective sheet on one side of the tab group, and weld one side of the tab group by a welding head close to the metal sheet protective sheet, such as Figure 7 As shown, Figure 7 Schematic diagram of a common guide handle welding a group of tabs provided in an embodiment of the present application Figure 1 , the common guide handle P1 is welded to the tab group by the upper welding head E1 on the ultrasonic welding machine, and a metal protection sheet F1 is welded to one side of the tab group. Comparative Example 5 is to set metal protection sheets on both sides of the tab group, weld the metal sheet protection sheets to both sides of the tab group by the upper welding head and the lower welding head of the ultrasonic welding machine, and weld the common guide handle to the tab group, such as Figure 8 As shown, Figure 8 Schematic diagram of a common guide handle welding a group of tabs provided in an embodiment of the present application Figure 2 The common guide handle P1 is welded together with the tab group through any welding head of the ultrasonic welding machine, and a metal protection sheet F1 is welded on one side of the tab group, and another metal protection sheet F2 is welded on the other side of the tab group.

[0073] Furthermore, the present application designs the shape and size of the Y-shaped pole ear connecting piece according to the battery overcurrent and the thickness of the battery cell, locates the junction of the forked ends of the Y-shaped pole ear connecting piece through the center position of the battery cell thickness, and assembles the solid-state battery through an integrated flat pressing and flat welding process, which effectively reduces the amplification of welding defects caused by high-temperature in-situ curing gas production, reduces welding equipment and process requirements, reduces welding defects, improves battery welding quality and consistency, and is beneficial to improving the overall performance of batteries, modules, and systems.

[0074] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. In the several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0075] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0076] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0077] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, and other media that can store program codes.

[0078] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A Y-shaped tab connector, characterized in that: The Y-shaped tab connector includes a guide handle and two forked ends. Among them, the maximum bifurcation distance between the two bifurcated ends in the horizontal direction and located on the inner side of the bifurcation is not less than the compacted thickness of the tab group of the stacked battery cell connected by the Y-shaped tab connecting piece, and the compacted thickness is used to indicate the metal layer thickness and value of the tab group of the stacked battery cell, the guide handle width in the horizontal direction is not less than the compacted thickness, and the length of the guide handle in the vertical direction is determined based on the target effective current flow area of ​​the tab group and the width of the tab group in the horizontal direction, and the target effective current flow area is determined according to the maximum current required by the battery and the current density of the tab material.

2. The Y-shaped tab connector according to claim 1, characterized in that: The guide handle width is the sum of the widths of the two forked ends. And / or, the maximum bifurcation distance is not less than the cell thickness of the laminated cell in the horizontal direction.

3. A method for welding a Y-shaped tab connecting piece, characterized in that: The method comprises: Placing the laminated battery core between an upper welding head and a lower welding head disposed opposite to each other on an ultrasonic welding machine, and controlling the preset welding area of ​​the tab group of the laminated battery core to be located in the overlapping area mapped from the upper welding head to the lower welding head; When the horizontal direction of the two forked ends of the Y-shaped pole tab connecting sheet is parallel to the thickness direction of the laminated battery core, the inner sides of the forks of the two forked ends of the Y-shaped pole tab connecting sheet are controlled to be close to the pole tab group of the laminated battery core, so that the two forked ends gather the pole tab group of the laminated battery core; Starting the ultrasonic welding machine to move the upper welding head and the lower welding head toward each other, and welding the two bifurcated ends of the Y-shaped tab connecting piece to the tab group; Wherein, the Y-shaped tab connecting piece is the Y-shaped tab connecting piece as described in any one of claims 1 to 2.

4. The method according to claim 3, characterized in that The method further comprises: Pre-welding the tab group; The two bifurcated ends of the Y-shaped tab connecting piece are welded to the tab group behind the pre-welded piece.

5. The method according to claim 4, characterized in that After pre-welding the tab group, the method further comprises: The target end of the tab group after pre-welding is neatly cut, and the target end is one end of the tab group close to the two bifurcated ends.

6. The method according to claim 3, characterized in that Before controlling the inner sides of the forked ends of the Y-shaped tab connector to approach the tab groups of the laminated battery cell, the method further includes: The target end of the tab group is cut neatly, and the target end is one end of the tab group close to the two bifurcated ends.

7. A battery, characterized in that: The battery comprises a battery housing, an electrolyte and a battery cell, wherein the battery cell comprises a Y-shaped tab connecting piece and a laminated battery cell, wherein the Y-shaped tab connecting piece is connected to the tab group of the laminated battery cell by welding. Wherein, the Y-shaped tab connecting piece is the Y-shaped tab connecting piece as described in any one of claims 1 to 2.

8. The battery according to claim 7, characterized in that The tab group of the laminated battery cell includes a positive tab group and a negative tab group, and the Y-shaped tab connecting piece includes a positive Y-shaped tab connecting piece welded to the positive tab group and a negative Y-shaped tab connecting piece welded to the negative tab group.

9. The battery according to claim 8, characterized in that The battery comprises a plurality of cells, the battery comprises at least one cell group, each cell group has the same number of cells, and each cell group is connected in series or in parallel according to battery capacity requirements. Among them, the battery cells in each battery cell group are connected in series or in parallel with the positive Y-shaped pole tab connecting piece and the negative Y-shaped pole tab connecting piece according to the capacity requirements of the battery cell group.

10. A method for preparing a battery, characterized in that: The battery comprises a battery shell, an electrolyte and a battery cell, the battery cell comprises a Y-shaped tab connecting piece and a laminated battery cell, the Y-shaped tab connecting piece is connected to the tab group of the laminated battery cell by welding, and the Y-shaped tab connecting piece is the Y-shaped tab connecting piece according to any one of claims 1 to 2, Wherein, the method comprises: After placing the battery cell and the electrolyte in the battery housing, curing the battery according to a preset curing temperature; After the cured battery is vacuum degassed at a preset vacuum pressure, the battery is packaged.

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