Pole lug welding device and pole lug welding method of soft package battery and battery

Abstract

The invention provides a tab welding device and tab welding method for a soft package battery and the battery, the tab welding device comprises a machine body, a welding head, a welding seat and a positioning clamp, the welding seat is arranged on one side of the machine body, the welding head is connected with the machine body, and the welding head is located above the welding seat; the welding seat comprises a welding table, a first groove and a second groove are formed in the welding table, the first groove is communicated with the second groove, the first groove is used for placing a battery cell, the second groove is used for placing a first tab, the positioning clamp is arranged above the first groove and is detachably connected with the welding table, and the positioning clamp and the second groove are used for fixing a second tab; the first tab and the second tab are welded by adopting the welding device, so that the welding speed is high, the yield is high, the conditions of battery piece breakage and pole piece pulling can be greatly improved, and meanwhile, the internal resistance of a battery cell is reduced by 15%.

Description

Technical Field

[0001] The present invention relates to the technical field of tab welding, and in particular to a tab welding device and a tab welding method for a soft-pack battery, and a battery. Background Art

[0002] In the soft-pack battery made of stacked sheets, since each pole piece needs to be welded together and welded to the outer pole ear, the welding point of the inner and outer pole ear usually needs to reserve a certain area in the aluminum-plastic film to accommodate it. This area is an invalid area that cannot increase the battery capacity for the battery. In order to reduce the volume of this invalid area, folding welding technology is required. In recent years, lithium-ion battery technology with silicon as the main negative electrode active material has become more and more mature, but due to the characteristics of silicon itself, when silicon is used as the negative electrode material of lithium-ion batteries, the macro expansion of the negative electrode will increase to more than 50%, which is much higher than the 20% of graphite. In the battery folded and welded using the traditional method, the large expansion of the negative electrode will cause the pole piece to be pulled due to expansion. Slight pulling will cause the pole piece to wrinkle and increase the internal resistance and lithium precipitation. Severe pulling will cause the pole piece to break; therefore, how to overcome the above-mentioned technical problems and defects has become a key issue that needs to be solved. Summary of the invention

[0003] In order to solve the problem that the silicon-containing negative electrode has a high expansion rate and severe pulling of the pole tab, which leads to wrinkling of the pole piece, and then causes the internal resistance of the battery to increase and lithium deposition to occur, and if the expansion is large, the pulling will be more severe and even the pole tab will break, the present invention provides a pole tab welding device and a pole tab welding method for a soft-pack battery, and a battery.

[0004] The technical solution adopted by the present invention to solve the above technical problems is as follows: A first aspect of the present invention provides a tab welding device for a soft-pack battery, comprising a body, a welding head, a welding seat and a positioning fixture, wherein the welding seat is arranged on one side of the body, the welding head is connected to the body, and the welding head is located above the welding seat; the welding seat comprises a welding platform, and a first groove and a second groove are provided on the welding platform, the first groove is connected to the second groove, the first groove is used to place the battery cell, and the second groove is used to place the first tab, the positioning fixture is arranged above the first groove and is detachably connected to the welding platform, and the positioning fixture and the second groove are used to fix the second tab.

[0005] Optionally, a notch is provided at one end of the first groove away from the second groove.

[0006] Optionally, limiting holes are provided on both sides of the first groove, and the positioning fixture is provided with protrusions at positions corresponding to the limiting holes, and the protrusions are detachably connected to the limiting holes.

[0007] Optionally, the positioning fixture is provided with a first limiting groove and a second limiting groove at a position corresponding to the second groove, and the second limiting groove is connected to the first limiting groove.

[0008] A second aspect of the present invention provides a method for welding a tab of a soft-pack battery, which uses the above-mentioned tab welding device for a soft-pack battery to perform welding, and includes the following welding steps: Step 1, place the battery cell into the first groove, bend the first pole ear so that the large surface of the first pole ear changes from vertical to horizontal and contacts with the second groove of the welding station; Step 2, embedding the protrusion of the positioning fixture into the limiting hole of the welding platform; Step 3, placing one end of the second pole tab in the second limiting groove of the positioning fixture, and extending the other end of the second pole tab into the second groove of the welding platform; Step 4: Start the welding head to weld the first pole tab to the second pole tab.

[0009] Optionally, step 3 further includes sticking tab glue on the outer side of the portion of the second tab located in the first limiting groove.

[0010] Optionally, step 4 further includes the following steps: Step 41: Cut off the excess parts of the first electrode tab and the second electrode tab; Step 42: Fold the first pole tab and the second pole tab 90 degrees respectively to complete the deflection welding.

[0011] Optionally, the first pole lug is an inner pole lug, and the second pole lug is an outer pole lug.

[0012] Optionally, a plurality of the first pole ears are provided, and a plurality of the second pole ears are correspondingly provided.

[0013] A third aspect of the present invention provides a battery, which is prepared by the above-mentioned method for welding the tabs of a soft-pack battery.

[0014] According to the tab welding device for a soft-pack battery provided by the present invention, by adopting the above-mentioned welding device to weld the first tab and the second tab, not only the welding speed is fast and the yield is high, but also the battery breakage and tab pulling conditions can be greatly improved, and at the same time the internal resistance of the battery cell can be reduced by 15%. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 It is a structural schematic diagram of a tab welding device for a soft-pack battery provided by an embodiment of the present invention; Figure 2 It is a structural schematic diagram of a positioning fixture in a tab welding device for a soft-pack battery provided by an embodiment of the present invention; Figure 3 It is a schematic diagram of welding a tab in a tab welding device for a soft-pack battery provided in one embodiment of the present invention; Figure 4 It is a schematic diagram of attaching tab glue in a tab welding device for a soft-pack battery provided in one embodiment of the present invention; Figure 5 It is a top view schematic diagram of a battery cell after being attached with lug glue according to an embodiment of the present invention; Figure 6 It is a top view schematic diagram of a battery core after welding the second pole ear provided by one embodiment of the present invention; Figure 7 This is a bottom view schematic diagram of a battery cell after welding the second electrode tab provided by an embodiment of the present invention; Figure 8 It is a schematic diagram of a battery cell provided by an embodiment of the present invention with redundant parts of the first pole tab and the second pole tab cut off; The reference numerals in the drawings of the specification are as follows: 1-body; 2-welding head; 3-welding seat; 31-soldering table; 311-first groove; 312-second groove; 313-notch; 314-limiting hole; 4-positioning fixture; 41-bump; 42-first limiting groove; 43-second limiting groove; 5-ear glue; 6-battery cell; 61-first ear; 62-second ear. DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0018] In the description of the present invention, it should be understood that the terms "longitudinal", "radial", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0019] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] like Figure 1 As shown, in one embodiment, the first aspect of the present invention provides a tab welding device for a soft-pack battery, comprising a body 1, a welding head 2, a welding seat 3 and a positioning fixture 4, the welding seat 3 is arranged on one side of the body 1, the welding head 2 is connected to the body 1, and the welding head 2 is located above the welding seat 3; the welding seat 3 comprises a welding platform 31, and a first groove 311 and a second groove 312 are provided on the welding platform 31, the first groove 311 is connected to the second groove 312, the first groove 311 is used to place the battery cell 6, and the second groove 312 is used to place the first tab 61, the positioning fixture 4 is arranged above the first groove 311 and is detachably connected to the welding platform 31, and the positioning fixture 4 and the second groove 312 are used to fix the second tab 62.

[0021] Specifically, one end of the first pole ear 61 is connected to one end of the lower surface of the battery cell 6, and the other end of the first pole ear 61 extends to a position flush with the upper surface of the battery cell 6 and is bent. A portion of the bent first pole ear 61 is fitted with the end of the battery cell 6, and the other portion of the bent first pole ear 61 is flush with the upper surface of the battery cell 6; the battery cell 6 is placed in the first groove 311, the size of the first groove 311 is the same as the size of the battery cell 6, the first pole ear 61 is located in the second groove 312, the positioning fixture 4 is connected to the welding table 31, the second pole ear 62 is placed between the positioning fixture 4 and the second groove 312, and the first pole ear 61 and the second pole ear 62 are welded by ultrasonic welding.

[0022] The present application adopts the above-mentioned welding device to weld the first pole ear 61 and the second pole ear 62, which not only has a fast welding speed and a high yield, but also can greatly improve the battery breakage and pole piece pulling conditions, while reducing the internal resistance of the battery cell 6 by 15%.

[0023] like Figure 1 As shown, in one embodiment, a notch 313 is provided at one end of the first groove 311 away from the second groove 312 .

[0024] Specifically, the notch 313 is U-shaped, and the other end of the notch 313 extends into the first groove 311 , so that the battery cell 6 can be placed in the first groove 311 through the notch 313 , so that the battery cell 6 can be replaced conveniently when welding is completed.

[0025] like Figure 1-Figure 2 As shown, in one embodiment, limiting holes 314 are provided on both sides of the first groove 311 , and the positioning fixture 4 is provided with protrusions 41 at positions corresponding to the limiting holes 314 , and the protrusions 41 are detachably connected to the limiting holes 314 .

[0026] Specifically, by embedding the protrusion 41 into the limiting hole 314, the positioning fixture 4 and the welding platform 31 are fixed in the direction of the plane where the welding platform 31 is located, preventing the positioning fixture 4 from moving along the plane where the welding platform 31 is located, thereby placing the second pole ear 62 between the positioning fixture 4 and the second groove 312 to limit the second pole ear 62.

[0027] like Figure 2 As shown, in one embodiment, a first limiting groove 42 and a second limiting groove 43 are provided at a position of the positioning fixture 4 corresponding to the second groove 312 , and the second limiting groove 43 is connected to the first limiting groove 42 .

[0028] Specifically, the first limiting groove 42 is used to limit the position of the pole ear glue 5, and the second limiting groove 43 is used to limit the position of the end of the second pole ear 62. The pole ear glue 5 is adhered to the outside of the second pole ear 62 and the second pole ear 62 is fixed to the first pole ear 61. The welding position is located in the area on the surface of the second pole ear 62 that is not covered by the pole ear glue 5.

[0029] like Figure 3-Figure 8 As shown, in one embodiment, the second aspect of the present invention provides a method for welding a tab of a soft-pack battery, which is welded using the above-mentioned tab welding device for a soft-pack battery, and includes the following welding steps: Step 1, place the battery cell 6 into the first groove 311, bend the first pole tab 61 so that the large surface of the first pole tab 61 changes from vertical to horizontal and contacts with the second groove 312 of the welding platform 31; Step 2, embed the protrusion 41 of the positioning fixture 4 into the limiting hole 314 of the welding platform 31; Step 3, placing one end of the second pole tab 62 in the second limiting groove 43 of the positioning fixture 4, and extending the other end of the second pole tab 62 into the second groove 312 of the welding platform 31; Step 4: Start the welding head 2 to weld the first electrode tab 61 and the second electrode tab 62 .

[0030] Specifically, the battery cell 6 is placed in the first groove 311. At this time, one end of the first pole ear 61 is connected to one end of the lower surface of the battery cell 6, and the other end of the first pole ear 61 is attached to the end of the battery cell 6 and extends in a direction perpendicular to the upper surface of the battery cell 6. The first pole ear 61 is located between the first groove 311 and the second groove 312. Then, the other end of the first pole ear 61 is bent at a position flush with the upper surface of the battery cell 6. A portion of the bent first pole ear 61 is attached to the end of the battery cell 6, and another portion of the bent first pole ear 61 is located in the second groove 312. Afterwards, the protrusion 41 of the positioning fixture 4 is embedded in the limiting hole 314, so that the positioning fixture 4 and the welding platform 31 are fixed in the direction of the plane where the welding platform 31 is located, and the second pole ear 62 is placed between the positioning fixture 4 and the second groove 312, and the first pole ear 61 and the second pole ear 62 are welded by ultrasonic welding.

[0031] The present application adopts the above-mentioned welding device to weld the first pole ear 61 and the second pole ear 62, which not only has a fast welding speed and a high yield, but also can greatly improve the battery breakage and pole piece pulling conditions, while reducing the internal resistance of the battery cell 6 by 15%.

[0032] like Figure 4-Figure 5 As shown, in one embodiment, step 3 further includes pasting the tab glue 5 on the outer side of the portion of the second tab 62 located in the first limiting groove 42 .

[0033] Specifically, the first limiting groove 42 is used to limit the position of the pole ear glue 5. The pole ear glue 5 is set in the first limiting groove 42 and adhered to the outside of the second pole ear 62, so as to fix the second pole ear 62 to the first pole ear 61, and the welding position is located in the area on the surface of the second pole ear 62 that is not covered by the pole ear glue 5.

[0034] like Figure 6-Figure 8 As shown, in one embodiment, step 4 further includes the following steps: Step 41: Cut off the redundant parts of the first electrode tab 61 and the second electrode tab 62; Step 42: Fold the first electrode tab 61 and the second electrode tab 62 by 90 degrees respectively to complete the deflection welding.

[0035] In step 41 , the redundant parts of the first pole tab 61 and the second pole tab 62 are cut off so that the first pole tab 61 and the second pole tab 62 after folding are of moderate length and convenient for connection with the pole.

[0036] In step 42, the first pole tab 61 and the second pole tab 62 are folded in the direction of the thickness of the battery cell 6, each folded 90°, thereby reducing the volume occupied by the first pole tab 61 and the second pole tab 62 in the length direction of the battery cell 6, thereby relatively increasing the length of the battery cell 6 and improving the capacity of the battery.

[0037] like Figure 6-Figure 8 As shown, in one embodiment, the first pole tab 61 is an inner pole tab, and the second pole tab 62 is an outer pole tab.

[0038] Specifically, the first pole ear 61 is connected to the battery cell 6, and the second pole ear 62 is welded to the first pole ear 61 after the first pole ear 61 is bent. This not only has a fast welding speed and a high yield, but also can greatly improve the battery breakage and pole piece pulling conditions, while reducing the internal resistance of the battery cell 6 by 15%.

[0039] like Figure 6-Figure 8 As shown, in one embodiment, a plurality of first pole tabs 61 are provided, and a plurality of second pole tabs 62 are correspondingly provided.

[0040] Specifically, one or more pole tabs may be provided at the same end of the battery cell 6 . Relatively, the number of the second pole tabs 62 is the same as the number of the first pole tabs 61 , so that after the first pole tabs 61 are bent, the second pole tabs 62 are welded to the corresponding first pole tabs 61 .

[0041] A third aspect of the present invention provides a battery, which is prepared by the above-mentioned method for welding the tabs of a soft-pack battery.

[0042] The battery of the present application is a lithium-ion battery, and its negative electrode adopts a silicon-based negative electrode. The welding method of the present application is used to weld the first pole ear 61 and the second pole ear 62. Not only is the welding speed fast and the yield rate high, but it can also avoid the high expansion rate of the silicon negative electrode, severe pulling of the pole ear, and wrinkling of the pole piece, which in turn causes the internal resistance of the battery to increase and lithium precipitation to occur. If the expansion is large and the pulling is more severe, it may even cause the problem of the pole ear breaking. The battery breakage and pole piece pulling are greatly improved, and at the same time the internal resistance of the battery cell 6 is reduced by 15%, thereby improving the production yield of lithium-ion batteries containing silicon negative electrodes.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A tab welding device for a soft-pack battery, characterized in that: It includes a body, a welding head, a welding seat and a positioning fixture, the welding seat is arranged on one side of the body, the welding head is connected to the body, and the welding head is located above the welding seat; the welding seat includes a welding platform, and the welding platform is provided with a first groove and a second groove, the first groove is connected to the second groove, the first groove is used to place the battery cell, and the second groove is used to place the first pole ear, the positioning fixture is arranged above the first groove and is detachably connected to the welding platform, and the positioning fixture and the second groove are used to fix the second pole ear.

2. The tab welding device for a soft-pack battery according to claim 1, characterized in that: A notch is provided at one end of the first groove away from the second groove.

3. The tab welding device for a soft-pack battery according to claim 1, characterized in that: Limiting holes are arranged on both sides of the first groove, and bumps are arranged at positions of the positioning fixture corresponding to the limiting holes, and the bumps are detachably connected to the limiting holes.

4. The tab welding device for a soft-pack battery according to claim 1, characterized in that: The positioning fixture is provided with a first limiting groove and a second limiting groove at a position corresponding to the second groove, and the second limiting groove is communicated with the first limiting groove.

5. A method for welding a tab of a soft-pack battery, using the tab welding device for a soft-pack battery according to any one of claims 1 to 4 for welding, characterized in that: The welding steps include: Step 1, place the battery cell into the first groove, bend the first pole ear, so that the large surface of the first pole ear changes from vertical to horizontal, and contacts with the second groove of the welding station; Step 2, embedding the protrusion of the positioning fixture into the limiting hole of the welding platform; Step 3, placing one end of the second pole tab in the second limiting groove of the positioning fixture, and extending the other end of the second pole tab into the second groove of the welding platform; Step 4: Start the welding head to weld the first pole tab to the second pole tab.

6. The method for welding the tabs of a soft-pack battery according to claim 5, characterized in that: The step 3 also includes pasting tab glue on the outer side of the portion of the second tab located in the first limiting groove.

7. The method for welding the tabs of a soft-pack battery according to claim 5, characterized in that: The step 4 also includes the following steps: Step 41: Cut off the excess parts of the first electrode tab and the second electrode tab; Step 42: Fold the first pole tab and the second pole tab 90 degrees respectively to complete the deflection welding.

8. The method for welding the tabs of a soft-pack battery according to claim 5, characterized in that: The first pole lug is an inner pole lug, and the second pole lug is an outer pole lug.

9. The method for welding the tabs of a soft-pack battery according to claim 5, characterized in that: A plurality of the first electrode tabs are provided, and a plurality of the second electrode tabs are correspondingly provided.

10. A battery, characterized in that: The battery is prepared by the tab welding method for a soft-pack battery according to any one of claims 5 to 9.

Images