Negative collector plate for ultrasonic spot bottom welding of large cylindrical lithium battery

Abstract

The utility model discloses a negative collector plate for ultrasonic spot bottom welding of a large cylindrical lithium battery. The negative collector plate comprises an ultrasonic welding needle, an ultrasonic welding needle raised welding head, a roll core, a steel shell, an ultrasonic welding bottom film, a collector plate and a laser welding groove, the steel shell is made of SPCC, the collector plate is round or strip-shaped, the collector plate is made of pure copper T2, the hardness of the collector plate is M-state HV48-59, the collector plate is plated with nickel on a single side, and the collector plate is used for preventing laser high reflection, an ultrasonic spot bottom welding surface is not plated with nickel, and self-discharge abnormity caused by nickel powder generated by ultrasonic spot bottom welding high-frequency vibration is prevented. And nickel plating affects the hardness of the collector plate and prevents the hardness from affecting the ultrasonic point bottom welding strength. According to the utility model, the resistance and point bottom pseudo soldering rate are reduced, the point bottom welding strength and the welding area are increased, so that the internal resistance of the battery is reduced to achieve the purpose of low charging and discharging temperature rise, the safety performance is improved, and high-rate charging and discharging can be realized; and the problem of rusting at a laser penetration welding shell bottom weld bead is solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to lithium battery negative current collecting disc technical field especially relates to a kind of negative current collecting disc for large cylindrical lithium battery ultrasonic spot bottom welding. BACKGROUND

[0002] The existing large cylindrical steel shell lithium battery full tab structure, negative current collecting disc and shell bottom main stream manufacturing process are resistance spot bottom welding form connection or laser penetration welding form, wherein resistance spot bottom welding drawbacks have that negative current collecting disc is fixed with shell bottom only by a welding spot, and welding area is small, and overcurrent capacity is low, and shell bottom rust problem is caused by the damage of nickel layer in shell bottom by laser penetration welding, which reduces the service life of battery and the investment cost of laser penetration welding equipment is high. SUMMARY

[0003] Based on the technical problems existing in the background art, the utility model provides a novel large cylindrical battery negative current collecting disc, the negative current collecting disc is designed as a single-sided copper-nickel plated structure, one side in contact with the ultrasonic welding needle is not plated with nickel, and the non-nickel plated side retains the soft state characteristics of copper for easy welding; the other side laser welding surface is plated with nickel to prevent high reflection during laser welding. The welding head of the ultrasonic welding needle is designed as a plurality of convex structures, which causes the negative current collecting disc and the shell bottom surface to rub against each other under the action of high-frequency vibration and pressure to form a plurality of small fusion nuclei between the molecular layers, the welding strength is high, the welding area is large, the abnormality of high temperature rise caused by large internal resistance due to resistance spot bottom virtual welding and small welding area is improved, and the rust problem of shell bottom caused by laser penetration welding is improved; compared with resistance welding and laser penetration welding, ultrasonic welding is a green, energy-saving and environmentally friendly welding method.

[0004] The utility model provides a kind of negative current collecting disc for large cylindrical lithium battery ultrasonic spot bottom welding, including ultrasonic welding needle, ultrasonic welding needle convex welding head, roll core, steel shell, ultrasonic welding bottom film, current collecting disc and laser welding recess;

[0005] The material of the steel shell is SPCC;

[0006] The current collecting disc is one of circular and strip-shaped;

[0007] The material of the current collecting disc is pure copper T2, with a hardness of M-state HV48-59, and a single-sided nickel plating for preventing laser high reflection. The ultrasonic spot bottom welding surface is not plated with nickel to prevent the generation of nickel powder due to high-frequency vibration during ultrasonic spot bottom welding, which causes abnormal self-discharge. The nickel plating affects the hardness of the current collecting disc, preventing the ultrasonic spot bottom welding strength from being affected by the hardness.

[0008] The two recesses are arranged at the welding position of the current collector plate and the winding core, so that the winding core is closely attached to the current collector plate without gap, and the abnormal explosion during welding is prevented.

[0009] The two elliptical grooves and the two circular grooves are arranged on the current collector plate, so that the electrolyte is infiltrated during liquid injection, and the weight reduction effect is achieved.

[0010] The two reinforcing ribs are arranged on the current collector plate, so that the overall rigidity of the current collector plate is effectively increased, and the deformation of the current collector plate is prevented.

[0011] The foolproof notch is arranged on the current collector plate, so that the assembly error is prevented during welding of the current collector plate and the negative end of the winding core.

[0012] The material of the ultrasonic welding needle and the ultrasonic welding bottom film is tool steel.

[0013] The ultrasonic welding needle is provided with a plurality of convex point structures on the convex welding head, and the number of the convex point structures can be adjusted according to the welding effect. During the welding process, a plurality of small fusion cores are formed at the design positions of the plurality of convex points on the ultrasonic welding head under the action of high-frequency vibration and pressure, so that the welding purpose is achieved. The welding area is large, the welding strength is high, and the edge of the convex welding head of the ultrasonic welding needle is provided with a round corner to prevent the sharp edge of the welding needle head from breaking the current collector plate after welding.

[0014] The center of the ultrasonic welding bottom film is provided with a cavity to prevent the shell bottom from being rubbed and the nickel from falling off during high-frequency vibration of the ultrasonic point bottom welding.

[0015] A negative current collector plate ultrasonic point bottom welding method for large cylindrical lithium battery ultrasonic point bottom welding, comprising the following steps:

[0016] S1: The negative end of the winding core is assembled and welded with the negative current collector plate. The one side of the negative current collector plate with the laser welding recess is not plated with nickel and is in contact with the negative end surface. The other side of the negative current collector plate is plated with nickel. The positive end of the winding core is welded with the positive current collector plate. The positive end of the winding core is sleeved with an insulating piece wrapped with high-temperature adhesive tape and then enters the steel shell.

[0017] S2: After entering the steel shell, the negative current collector plate is closely attached to the shell bottom of the steel shell.

[0018] S3: After entering the steel shell, the winding core penetrates the ultrasonic welding needle. The negative current collector plate and the shell bottom of the steel shell are melted together under the action of the pressure, pre-pressing time, welding time, welding frequency and pressure maintaining time of the ultrasonic welding machine. A plurality of small fusion cores are formed at the design positions of the plurality of convex points on the convex welding head of the ultrasonic welding needle, so that the welding purpose is achieved. The ultrasonic point bottom welding form is adopted.

[0019] S4: The subsequent production process of the battery is carried out.

[0020] The utility model discloses a beneficial effect is: reduce resistance and point bottom false soldering rate, increase point bottom welding strength and welding area to reduce battery internal resistance to reach the purpose of low temperature rise of charge and discharge, improve safety performance, can big ratio charge and discharge, improve laser penetration welding shell bottom weld groove rust problem of place;

[0021] A negative pole current collecting disc is not plated with nickel on the ultrasonic point bottom welding surface, and is plated with nickel on the laser welding surface, the ultrasonic point bottom welding process is used to replace the traditional resistance point bottom welding and laser penetration welding process, the ultrasonic point bottom welding needle head is designed as the structure of multiple convex points, which is easier to weld the negative current collecting disc and the shell under pressure and high-frequency vibration, and increases welding area and welding strength. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is the structure schematic diagram of the utility model;

[0023] Figure 2 It is the structure schematic diagram of the utility model's A;

[0024] Figure 3 It is the structure schematic diagram of the utility model's ultrasonic welding needle convex welding head;

[0025] Figure 4 It is the structure schematic diagram of the utility model's current collecting disc's A section;

[0026] Figure 5 It is the structure schematic diagram of the utility model's current collecting disc's B section;

[0027] Figure 6 It is the structure schematic diagram of the utility model's current collecting disc's C section;

[0028] Figure 7 It is the ultrasonic point bottom welding form of the utility model;

[0029] Figure 8 It is the structure schematic diagram of the utility model's nickel-plated welding surface;

[0030] Figure 9 It is the structure schematic diagram of the utility model's current collecting disc's B section side view.

[0031] In the drawing: 1, ultrasonic welding needle, 2, ultrasonic welding needle convex welding head, 3, winding core, 4, negative pole current collecting disc, 5, steel shell, 6, ultrasonic welding bottom film, 8, oval notch, 9, reinforcing rib, 10, laser welding recessed groove place, 11, foolproof gap, 12, circular notch. DETAILED DESCRIPTION

[0032] The utility model will be further explained in connection with specific embodiment. EMBODIMENT

[0033] REFERENCE Figures 1-9The embodiment provides a negative current collector disc for ultrasonic spot welding of a large cylindrical lithium battery, which comprises an ultrasonic welding needle 1, an ultrasonic welding needle convex welding head 2, a roll core 3, a steel shell 5, an ultrasonic welding bottom film 6, a current collector disc and a laser welding groove 10.

[0034] The steel shell 5 is made of SPCC.

[0035] The current collector disc is in one of a circular shape and a strip shape.

[0036] The current collector disc is made of pure copper T2 and has a hardness of M-mode HV48-59, and is single-sided plated with nickel, which is used for preventing laser high reflection, ultrasonic spot welding surface is not plated with nickel to prevent nickel powder from being generated due to ultrasonic spot welding high-frequency vibration to cause self-discharge abnormality, and the plating of nickel affects the hardness of the current collector disc to prevent the hardness from affecting the ultrasonic spot welding strength.

[0037] The current collector disc is provided with two grooves at a welding position of the current collector disc and the roll core 3, and is closely attached to the roll core 3 without a gap, so that explosion abnormality is prevented during welding.

[0038] The current collector disc is provided with two elliptical notches 8 and two circular notches 12, so that the electrolyte is infiltrated during liquid injection, and the weight is reduced.

[0039] The current collector disc is provided with two reinforcing ribs 9, and the reinforcing ribs 9 effectively increase the overall rigidity of the current collector disc to prevent the current collector disc from being deformed.

[0040] The current collector disc is provided with a foolproof notch 11, and the current collector disc is prevented from being assembled incorrectly when the current collector disc is welded to a negative electrode end of the roll core 3.

[0041] The ultrasonic welding needle 1 and the ultrasonic welding bottom film 6 are made of tool steel.

[0042] The ultrasonic welding needle convex welding head 2 is provided with a plurality of convex point structures, the number of which can be adjusted according to welding effect, a plurality of small fusion cores are formed at the plurality of convex point design positions of the ultrasonic welding head under the action of high-frequency vibration and pressure during the welding process, the welding area is large, the welding strength is high, and the edge of the ultrasonic welding needle convex welding head 2 is provided with a round corner to prevent the edge of the welding needle head from being sharp after welding and the current collector disc from being pressed and broken.

[0043] The ultrasonic welding bottom film 6 is provided with a cavity at a central position, which prevents traces and nickel falling from being rubbed on the shell bottom during ultrasonic spot welding high-frequency vibration.

[0044] A negative current collector disc for ultrasonic spot welding of a large cylindrical lithium battery and an ultrasonic spot welding method thereof are provided.

[0045] S1: the negative terminal of the winding core 3 is assembled and welded with the negative current collector disc 4, the side of the negative current collector disc 4 which is not plated with nickel and which is laser welded is in contact with the negative terminal surface, the other side of the negative current collector disc 4 which is plated with nickel is laser welded, the positive terminal of the winding core 3 is welded with the positive current collector disc, and the positive terminal of the winding core 3 is sleeved with an insulating sheet and high-temperature adhesive tape and then enters the steel shell 5;

[0046] S2: after entering the steel shell 5, the negative current collector disc 4 is tightly attached to the bottom of the steel shell 5;

[0047] S3: after entering the steel shell 5, the winding core 3 penetrates the ultrasonic welding needle 1, and the negative current collector disc 4 and the bottom of the steel shell 5 are fused together under the action of the pressure, pre-pressing time, welding time, welding frequency and pressure maintaining time of the ultrasonic welding machine, a plurality of small fusion cores are formed by the plurality of protrusions at the ultrasonic welding needle protrusion welding head 2, the welding purpose is achieved, and the ultrasonic point bottom welding form is adopted;

[0048] S4: the subsequent production process of the battery is performed.

[0049] In the embodiment, the steel shell 5 is made of SPCC nickel-plated material, the bottom thickness is 0.7 mm, the negative current collector disc 4 is made of pure copper T2, the side which is laser welded with the negative terminal surface of the winding core 3 is plated with nickel, the other side which is in contact with the ultrasonic welding needle 1 is not plated with nickel, the state of the copper is M, the hardness is HV48-59, the outer diameter is φ38.5 mm, the raw material thickness is 0.3 mm, the winding core 3 is sleeved with an insulating sheet and high-temperature adhesive tape after being welded with the positive and negative current collector discs, and then enters the shell;

[0050] The ultrasonic welding needle 1 is inserted, as shown in Figure 6 and Figure 7 , the negative current collector disc 4 and the bottom are welded by adopting ultrasonic point bottom welding, the ultrasonic welding head is designed as 19 protrusions, the high-frequency vibration wave is transmitted to the negative current collector disc 4 and the bottom, the negative current collector disc 4 and the bottom surface are rubbed with each other to form fusion between the molecular layers under the condition of pressure, a plurality of small fusion cores are formed, and the welding strength and welding area are improved.

[0051] In the embodiment, it can be known from the above large cylindrical current collector disc and ultrasonic point bottom welding method that the negative current collector disc 4 is designed with a notch to facilitate liquid injection and achieve the effect of weight reduction, the reinforcing rib 9 is designed to increase the rigidity of the current collector disc to prevent deformation, the foolproof notch 11 is designed to distinguish the front and back surfaces to prevent assembly errors, the two laser welding grooves are designed to be more tightly attached to the winding core 3 without gaps to prevent abnormal explosion during welding, and the single-side nickel plating is designed to prevent laser high reflection on the laser welding surface.

[0052] As shown in Figure 8 , the ultrasonic point bottom welding surface is not plated with nickel to prevent nickel powder from causing self-discharge abnormality due to ultrasonic point bottom welding high-frequency vibration, and the nickel plating affects the hardness of the current collector disc to prevent the hardness from affecting the ultrasonic point bottom welding strength.

[0053] The head of the ultrasonic welding needle 1 is designed with convex point structure, and the number of convex points can be adjusted according to the welding effect. Under the action of high-frequency vibration and pressure in the welding process, multiple small fusion cores are formed at the multiple convex point design positions of the ultrasonic welding head, so that the welding purpose is achieved. The welding area is large, the welding strength is high, the production efficiency is high, the problems of abnormality such as virtual welding of the point bottom and large internal resistance caused by small area and high temperature rise of charging and discharging are improved, and the problem of rusting of the laser penetration welding shell bottom is improved.

[0054] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A negative current collector plate for ultrasonic spot butt welding of large cylindrical lithium batteries, characterized in that, It comprises an ultrasonic welding needle (1), an ultrasonic welding needle convex welding head (2), a winding core (3), a negative current collector (4), a steel shell (5), an ultrasonic welding bottom film (6) and a laser welding groove (10); The material of the steel shell (5) is SPCC; The negative current collector (4) is one of a circular shape and a strip shape; The material of the negative current collector (4) is pure copper T2, the hardness is M mode HV48-59, and the single side is plated with nickel, which is used for preventing high laser reflection; Two grooves are arranged at the welding position of the negative current collector (4) and the winding core (3); Two oval notches (8) and two circular notches (12) are arranged on the negative current collector (4); Two reinforcing ribs (9) are arranged on the negative current collector (4), which are used for preventing the deformation of the negative current collector (4); A foolproof notch (11) is arranged on the negative current collector (4); The materials of the ultrasonic welding needle (1) and the ultrasonic welding bottom film (6) are tool steel; A plurality of convex structures are arranged on the ultrasonic welding needle convex welding head (2), and a round corner is arranged at the edge of the ultrasonic welding needle convex welding head (2); A cavity is arranged at the center position of the ultrasonic welding bottom film (6).

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