Lithium ion battery suitable for PACK laser welding

Abstract

The utility model discloses a lithium ion battery suitable for PACK laser welding, which comprises a lithium ion battery suitable for PACK laser welding, a positive electrode end aluminum sheet, a positive electrode end top cover, a steel shell, a negative electrode end aluminum sheet, an ultrasonic welding spot, a PACK aluminum busbar, a positive electrode end laser welding track, a negative electrode end laser welding track and a module, the positive electrode end and the negative electrode end of the lithium ion battery suitable for PACK laser welding are both provided with sunken grooves, and the positive electrode end aluminum sheet is located in the sunken groove of the positive electrode end of the lithium ion battery suitable for PACK laser welding and welded to the positive electrode end top cover. According to the utility model, the aluminum sheets are welded on the positive and negative end faces of the steel shell lithium battery, so that the steel shell lithium battery can be welded with the aluminum busbars and the positive and negative end aluminum sheets in PACK welding, and finally, the advantages of good welding effect, small welding heat affected zone, incapability of welding through the battery, light PACK weight and low cost are achieved.

Description

Technical Field

[0001] This utility model relates to the field of lithium-ion battery technology, and in particular to a lithium-ion battery suitable for PACK laser welding. Background Technology

[0002] In existing large cylindrical steel-cased lithium batteries, the busbars to the positive and negative terminals of the battery are typically laser-welded during PACK welding. Common busbar materials include nickel-plated copper, pure nickel, nickel-plated steel, and aluminum. While nickel-plated copper, pure nickel, and nickel-plated steel exhibit good welding results with steel-cased lithium batteries, their high melting points require high-power laser welding. Welding the negative terminal can easily lead to weld penetration and leakage, over-welding causing the separator to melt and resulting in internal short circuits. Furthermore, the weight of nickel-plated copper, pure nickel, and nickel-plated steel busbars increases the overall weight of the PACK module, and their high material cost increases PACK costs. Aluminum busbars offer advantages over the aforementioned materials, including a low melting point, low power laser welding with minimal heat impact, and lighter weight, reducing overall PACK weight and lower material costs. However, aluminum busbars are prone to explosions and inclusions in the molten pool during laser welding with steel-cased batteries. Compared to steel-cased lithium batteries, aluminum-cased lithium batteries in the industry use aluminum rivets for both the positive and negative terminals. When welding the PACK, aluminum busbars are used to weld to the aluminum rivets at the positive and negative terminals. Aluminum to aluminum is welded by laser welding, which has advantages such as good welding effect, low welding power, light weight, and low price. Utility Model Content

[0003] Based on the technical problems existing in the background technology, this utility model proposes a lithium-ion battery suitable for PACK laser welding.

[0004] This utility model proposes a lithium-ion battery suitable for PACK laser welding, comprising a lithium-ion battery suitable for PACK laser welding, a positive terminal aluminum sheet, a positive terminal top cover, a steel shell, a negative terminal aluminum sheet, an ultrasonic welding joint, a PACK aluminum busbar, a positive terminal laser welding trajectory, a negative terminal laser welding trajectory, and a module. The positive and negative terminals of the lithium-ion battery suitable for PACK laser welding are provided with recessed grooves. The positive terminal aluminum sheet is located in the recessed groove of the positive terminal of the lithium-ion battery suitable for PACK laser welding and is welded to the positive terminal top cover. The negative terminal aluminum sheet is located in the recessed groove of the negative terminal of the lithium-ion battery suitable for PACK laser welding and is welded to the steel shell. The battery structure dimensions remain unchanged and do not affect the PACK structure dimensions.

[0005] As a preferred embodiment of this utility model, the PACK aluminum busbar is made of aluminum, which is lightweight and can reduce the weight of the PACK, has a low melting point and is easy to laser weld, and is inexpensive and can reduce costs.

[0006] As a preferred embodiment of this utility model, the PACK aluminum busbar is welded to a lithium-ion battery suitable for PACK laser welding, achieving the same welding method and effect for steel-cased batteries as for aluminum-cased batteries in PACK welding.

[0007] In a preferred embodiment of this invention, the upper surface of the positive end aluminum sheet is horizontal to the edge of the positive end top cover.

[0008] In a preferred embodiment of this utility model, the bottom surface of the negative end aluminum sheet is horizontal to the bottom edge of the steel shell.

[0009] As a preferred embodiment of this utility model, the welding method between the positive end aluminum sheet and the positive end top cover is one of ultrasonic welding, resistance welding, and laser welding.

[0010] As a preferred embodiment of this utility model, the welding method between the negative end aluminum sheet and the steel shell is one of ultrasonic welding, resistance welding, and laser welding.

[0011] As a preferred embodiment of this utility model, the welding method between the PACK aluminum busbar and the lithium-ion battery suitable for PACK laser welding is laser welding.

[0012] The beneficial effects of this utility model are:

[0013] 1. By welding aluminum sheets to the positive and negative terminals of the steel-cased lithium battery, aluminum busbars can be used to weld the positive and negative terminal aluminum sheets to the PACK during the PACK welding process. This results in advantages such as good welding effect, small heat-affected zone, no battery burn-through, light PACK weight, and reduced cost.

[0014] 2. The positive terminal top cover and negative terminal bottom cover are designed with recessed grooves, in which aluminum adapter plates are welded. The aluminum plates are pre-welded to the positive terminal cap and the negative terminal steel shell bottom. The recessed grooves on the positive and negative terminal surfaces do not change the overall height of the battery after the aluminum adapter plates are welded, and will not affect the overall structural dimensions of the PACK after welding. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the lithium-ion battery in this utility model;

[0016] Figure 2 In this utility model Figure 1 Enlarged view of the a structure;

[0017] Figure 3 This is an enlarged view of structure b in this utility model;

[0018] Figure 4 This is a schematic diagram of the positive end aluminum sheet and the ultrasonic welding joint in this utility model;

[0019] Figure 5 This is a schematic diagram of the negative end aluminum sheet and the ultrasonic welding joint in this utility model;

[0020] Figure 6 This is a schematic diagram of the structure of the PACK aluminum busbar in this utility model;

[0021] Figure 7 This is a schematic diagram of the positive extreme laser welding trajectory, the negative extreme laser welding trajectory, and the module in this utility model.

[0022] In the diagram: 1. Lithium-ion battery suitable for PACK laser welding; 2. Positive end aluminum sheet; 3. Positive end top cover; 4. Steel shell; 5. Negative end aluminum sheet; 6. Ultrasonic welding joint; 7. PACK aluminum busbar; 8. Positive end laser welding trajectory; 9. Negative end laser welding trajectory; 10. Module. Detailed Implementation

[0023] The present invention will be further explained below with reference to specific embodiments. Example

[0024] refer to Figure 1-7 This embodiment proposes a lithium-ion battery suitable for PACK laser welding, including a lithium-ion battery 1 suitable for PACK laser welding, a positive terminal aluminum sheet 2, a positive terminal top cover 3, a steel shell 4, a negative terminal aluminum sheet 5, an ultrasonic welding point 6, a PACK aluminum busbar 7, a positive terminal laser welding trajectory 8, a negative terminal laser welding trajectory 9, and a module 10. The positive and negative terminals of the lithium-ion battery 1 suitable for PACK laser welding are provided with recessed grooves. The positive terminal aluminum sheet 2 is located in the recessed groove of the positive terminal of the lithium-ion battery 1 suitable for PACK laser welding and is welded to the positive terminal top cover 3. The negative terminal aluminum sheet 5 is located in the recessed groove of the negative terminal of the lithium-ion battery 1 suitable for PACK laser welding and is welded to the steel shell 4. The battery structure size remains unchanged and does not affect the PACK structure size.

[0025] The positive terminal aluminum sheet 2 and the positive terminal top cover 3 are welded together during the cap manufacturing process. The negative terminal aluminum sheet 5 and the bottom of the steel shell 4 are welded together after the steel shell 4 is stamped and nickel-plated. After the battery is assembled, there is no need to weld the aluminum sheet again, which simplifies the battery production process and improves production efficiency.

[0026] The ultrasonic welding needle and resistance welding needle are designed with a convex structure at the head. The number of convex points can be adjusted according to the welding effect. During the welding process, under the action of high frequency vibration and pressure, multiple small molten nuclei are formed at the multiple convex points of the ultrasonic welding head to achieve the welding purpose. The welding area is large, the welding strength is high, and the welding appearance is beautiful. The aluminum sheet is welded to the positive and negative ends by ultrasonic welding points 6. There are 4 or more ultrasonic welding points 6.

[0027] The lithium-ion battery 1 suitable for PACK laser welding can achieve the purpose of using PACK aluminum busbar 7 during PACK welding by welding aluminum sheets at the positive and negative ends. Aluminum has a low melting point, and laser welding can use low power and a small heat-affected area, avoiding abnormalities such as battery leakage due to high power welding and internal short circuit caused by heat shrinkage of the core separator due to high power.

[0028] The PACK aluminum busbar 7 is made of aluminum, which is lightweight, reducing the weight of the PACK; has a low melting point, making it easy to laser weld; and is inexpensive, reducing costs. The module 10 welds the PACK aluminum busbar 7 to the lithium-ion battery 1, which is suitable for PACK laser welding, using laser welding. This achieves the same welding method and effect in PACK welding as in aluminum-cased batteries for steel-cased batteries. The upper surface of the positive terminal aluminum sheet 2 is horizontal with the edge of the positive terminal top cover 3, and the bottom surface of the negative terminal aluminum sheet 5 is horizontal with the bottom edge of the steel shell 4. The welding method for the positive terminal aluminum sheet 2 and the positive terminal top cover 3 is one of ultrasonic welding, resistance welding, or laser welding. The welding method for the negative terminal aluminum sheet 5 and the steel shell 4 is one of ultrasonic welding, resistance welding, or laser welding. The welding method for the PACK aluminum busbar 7 and the lithium-ion battery 1, which is suitable for PACK laser welding, is laser welding.

[0029] The specific manufacturing process of this utility model is as follows:

[0030] S1: The top cap 3 of the positive end is pre-welded together with the aluminum sheet 2 of the positive end;

[0031] S2: The bottom of the steel shell 4 is pre-welded together with the negative end aluminum sheet 5;

[0032] S3: Using welded aluminum sheets to produce caps and steel shells for lithium-ion batteries suitable for PACK laser welding 1;

[0033] S4: Select batteries with the same consistency and weld them to the positive end aluminum sheet 2 via positive end laser welding trajectory 8 and to the negative end aluminum sheet 5 via negative end laser welding trajectory 9. Finally, the batteries are welded into a module 10.

[0034] The following are the design data for this utility model:

[0035] 1. The cap has a top cover thickness of 1mm, a recessed groove depth of 0.8mm, an aluminum sheet thickness of 0.8mm and a diameter of φ13.5mm. During cap production, the aluminum sheet and the top cover are ultrasonically welded, and the flatness after welding is 0.02mm.

[0036] 2. The steel shell 4 has a bottom thickness of 0.7mm, a recessed groove depth of 0.8mm, and an aluminum sheet thickness of 0.8mm and a diameter of φ35mm. During the production of steel shell 4, the aluminum sheet and the bottom of the shell are welded by ultrasonic welding, and the flatness after welding is 0.03mm.

[0037] 3. Using welded aluminum sheet caps and steel shells, lithium-ion batteries are produced through a grooving sealing mechanical stamping process. The battery diameter is φ40.2mm and the height is 135mm.

[0038] 4. The aluminum busbar 7 in the PACK is 2mm thick, and its external dimensions are designed according to the PACK structure;

[0039] 5. The PACK aluminum busbar 7 is welded to the battery to form a series-parallel module by laser welding. The busbar is welded to the positive terminal aluminum sheet 2 of the battery with a welding diameter of φ5mm and a welding width of 2mm. The busbar is welded to the negative terminal aluminum sheet 5 of the battery with a welding diameter of φ10mm and a welding width of 2mm.

[0040] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A lithium-ion battery suitable for PACK laser welding, comprising a lithium-ion battery (1) suitable for PACK laser welding, a positive terminal aluminum sheet (2), a positive terminal top cover (3), a steel shell (4), a negative terminal aluminum sheet (5), an ultrasonic welding point (6), a PACK aluminum busbar (7), a positive terminal laser welding trajectory (8), a negative terminal laser welding trajectory (9), and a module (10), characterized in that, The lithium-ion battery (1) suitable for PACK laser welding has recessed grooves on both the positive and negative terminals. The positive terminal aluminum sheet (2) is located in the recessed groove of the positive terminal of the lithium-ion battery (1) suitable for PACK laser welding and is welded to the positive terminal top cover (3). The negative terminal aluminum sheet (5) is located in the recessed groove of the negative terminal of the lithium-ion battery (1) suitable for PACK laser welding and is welded to the steel shell (4). The battery structure size remains unchanged and does not affect the PACK structure size.

2. A lithium-ion battery suitable for PACK laser welding according to claim 1, characterized in that, The PACK aluminum busbar (7) is made of aluminum, which is lightweight and can reduce the weight of the PACK. It has a low melting point, is easy to laser weld, and is inexpensive, which can reduce costs.

3. A lithium-ion battery suitable for PACK laser welding according to claim 1, characterized in that, The PACK aluminum busbar (7) is welded to the lithium-ion battery (1) suitable for PACK laser welding, achieving the same welding method and effect for steel-cased batteries as for aluminum-cased batteries in PACK welding.

4. A lithium-ion battery suitable for PACK laser welding according to claim 1, characterized in that, The upper surface of the positive end aluminum sheet (2) is horizontal with the edge of the positive end top cover (3).

5. A lithium-ion battery suitable for PACK laser welding according to claim 1, characterized in that, The bottom surface of the negative end aluminum sheet (5) is horizontal with the bottom edge of the steel shell (4).

6. A lithium-ion battery suitable for PACK laser welding according to claim 1, characterized in that, The welding method of the positive end aluminum sheet (2) and the positive end top cover (3) is one of ultrasonic welding, resistance welding, and laser welding.

7. A lithium-ion battery suitable for PACK laser welding according to claim 1, characterized in that, The welding method between the negative end aluminum sheet (5) and the steel shell (4) is one of ultrasonic welding, resistance welding, or laser welding.

8. A lithium-ion battery suitable for PACK laser welding according to claim 3, characterized in that, The welding method between the PACK aluminum busbar (7) and the lithium-ion battery (1) suitable for PACK laser welding is laser welding.

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