Battery cell tab connecting structure and secondary battery

Abstract

The utility model discloses a battery cell tab connecting structure and a secondary battery. The battery cell tab connecting structure comprises a battery cell body and a tab connecting structure, one end of the first tab is electrically connected with at least one end part of the battery cell body, the other end of the first tab is divided into N parts along the thickness direction, and N is greater than or equal to 2; the second tab comprises a welding end and an external connection end, and the welding end is cut into N parts along the thickness direction; wherein the N parts of first tabs and the N parts of second tabs are welded and connected in a one-to-one correspondence manner. According to the battery cell tab connecting structure provided by the utility model, one-time tab welding is changed into multi-time welding, and only the welding end of the second tab is cut, so that the welding effectiveness is improved, the abnormities of foil breakage and insufficient welding during welding are reduced, the problem of welding failure caused by over-thick tabs and foils is effectively solved, and the battery cell tab connecting structure is suitable for large-scale production. And the problem of packaging liquid leakage caused by traditional multi-tab packaging is avoided.

Description

Technical Field

[0001] The utility model relates to the field of secondary batteries, in particular to a battery cell tab connection structure and a secondary battery. Background Art

[0002] At present, the stacking process of battery cells mainly forms conductors by reserving blank areas in the current collector for welding with the tabs. The welding mainly uses ultrasound to overlap the blank areas of the current collector with the tabs, and connects the tabs and the current collector through ultrasonic energy.

[0003] With the consumer market's demand for energy density, the development of large-capacity battery cells has become a trend. For some thick and large battery cells, the more electrode layers there are, the higher the power required for welding. However, in actual use, there will still be over-welding or foil welding cracks on the surface directly in contact with the welding head. The side farther away from the welding head will have insufficient welding power, resulting in welding and the electrode not being bonded, which seriously affects the quality of the battery cell.

[0004] Therefore, an innovative technical solution is needed to improve the connection structure of the battery cell tabs. The design for such thick battery cells can effectively ensure welding reliability, reduce the abnormalities of welding foil cracking and welding cold joints, improve product quality and safety, and improve production efficiency. Utility Model Content

[0005] The purpose of the utility model is to provide a battery cell tab connection structure to address the deficiencies of the prior art and reduce the occurrence of foil rupture and cold welds during welding.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A battery cell tab connection structure,

[0008] Battery cell body;

[0009] a first electrode tab, wherein one end of the first electrode tab is electrically connected to at least one end of the battery cell body, and the other end of the first electrode tab is divided into N parts along the thickness direction, where N is greater than or equal to 2;

[0010] The second tab includes a welding end and an external connection end, wherein the welding end is cut into N parts along the thickness direction;

[0011] The N first electrode tabs and the N second electrode tabs are welded and connected in a one-to-one correspondence.

[0012] Preferably, the other end of the first electrode tab is divided into N equal parts along the thickness direction, and the welding end of the second electrode tab is cut into N equal parts along the thickness direction.

[0013] Preferably, a packaging area is provided between the welding end and the external connection end, and the packaging area is provided with tab glue, and the distance between the lower edge of the tab glue and the upper edge of the welding end is h, wherein h satisfies the relationship: 3mm≤h≤8mm.

[0014] Preferably, the total thickness of the first electrode tab is 300-2000 μm.

[0015] Preferably, the total thickness of the second electrode tab is 300-2000 μm.

[0016] Preferably, the thickness of each of the first electrode tabs is 100-200 μm.

[0017] Preferably, the thickness of each of the second electrode tabs is 100-200 μm.

[0018] Preferably, the width of the first electrode tab is 10-500 mm, and the width of the second electrode tab is 10-500 mm.

[0019] In addition, the present invention also provides a secondary battery, comprising the above-mentioned battery cell tab connection structure.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1) The battery cell tab connection structure provided by this utility model changes the tab welding process from a single welding process to multiple welding processes, and only the welding end of the second tab is cut. This improves welding efficiency, reduces foil cracking and weld defects during welding, effectively improves welding failures caused by excessive tab and foil thickness, and avoids package leakage problems caused by traditional multi-tab packaging. During pack assembly, only the external connection end of the second tab needs to be welded, eliminating the need for welding multiple tabs during pack assembly.

[0022] 2) In the battery cell tab connection structure provided by the present invention, a spacing h is set between the lower edge of the tab glue of the second tab and the upper edge of the welding end, and h is controlled to be 3-8mm. If h is too large, the cutting area will be relatively small, and the contact area during the trace connection will be relatively small, which will increase the difficulty of welding. If h is too small, the tab glue may be damaged when cutting the second tab, thereby affecting the battery cell packaging performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the battery cell tab connection structure according to an embodiment of the present invention.

[0024] Figure 2 Schematic diagram of a cross section of a second tab welding end according to an embodiment of the present invention.

[0025] Figure 3 FIG. 1 is a top view of a second electrode tab according to an embodiment of the present invention.

[0026] Among them, 1-battery cell; 2-first pole tab; 3-second pole tab; 31-pole tab glue; 32-welding end; 33-external connection end. DETAILED DESCRIPTION

[0027] In order to make the technical solutions and advantages of the present invention clearer, the present invention and its beneficial effects will be described in further detail below in conjunction with specific implementation methods and the accompanying drawings, but the implementation methods of the present invention are not limited thereto.

[0028] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of this utility model, "plurality" means two or more, unless otherwise specifically defined.

[0029] In order to make the technical solutions and advantages of the present invention clearer, the present invention and its beneficial effects will be described in further detail below in conjunction with specific implementation methods and the accompanying drawings, but the implementation methods of the present invention are not limited thereto.

[0030] like Figure 1-3 As shown, according to the first aspect of the present application, the present application aims to provide a battery cell tab connection structure, comprising:

[0031] Battery cell body 1;

[0032] A first tab 2, one end of which is electrically connected to at least one end of the cell body, and the other end of which is divided into N parts along the thickness direction, where N is greater than or equal to 2;

[0033] The second electrode tab 3 includes a welding end 32 and an external connection end 33, and the welding end 32 is cut into N parts along the thickness direction;

[0034] The N first electrode tabs 2 and the N second electrode tabs 3 are welded and connected in a one-to-one correspondence.

[0035] The other end of the first electrode tab is divided into N parts along the thickness direction, and the welding end 32 of the second electrode tab 3 is cut into N parts along the welding direction and then welded one by one. The welding is changed from one time to multiple times, and only the welding end 32 of the second electrode tab 3 is cut. This improves the welding effectiveness while improving the welding failure problem caused by the excessive thickness of the electrode tab and foil.

[0036] In some embodiments, the other end of the first electrode tab is divided into N equal parts along the thickness direction, and the welding end of the second electrode tab is cut into N equal parts along the thickness direction.

[0037] In some embodiments, a packaging area is provided between the welding end 32 and the external connection end 33. The packaging area is provided with tab glue 31. The distance between the lower edge of the tab glue 31 and the upper edge of the welding end 32 is h, where h satisfies the relationship: 3mm≤h≤8mm, and can be, for example, 3mm, 4mm, 5mm, 6mm, 7mm, or 8mm. If h is too large, the cutting area will be relatively small, and the contact area during trace welding will be relatively small, making welding more difficult. If h is too small, the tab glue may be damaged when cutting the second tab, thereby affecting the battery cell packaging performance.

[0038] In some embodiments, the total thickness of the first electrode tab 2 is 300-2000 μm, for example, 300 μm, 500 μm, 1000 μm, 1500 μm, or 2000 μm.

[0039] In some embodiments, the total thickness of the second electrode tab 3 is 300-2000 μm, for example, 300 μm, 500 μm, 1000 μm, 1500 μm, or 2000 μm.

[0040] In some embodiments, the thickness of each first electrode tab 2 is 100-200 μm, for example, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 110 μm, 120 μm, 130 μm, or 140 μm.

[0041] In some embodiments, the thickness of each second electrode tab 3 is 100-200 μm, for example, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 110 μm, 120 μm, 130 μm, or 140 μm.

[0042] In some embodiments, the width of the first tab 2 is 10-500 mm, and the width of the second tab 3 is 10-500 mm. If the thickness is too small, it will be difficult to split and difficult to form. If the thickness is too large, it will increase the difficulty of welding.

[0043] In some embodiments, the first electrode tab 2 is made of a conductive material, such as copper, aluminum, nickel, nickel-plated copper, tin-plated copper, or gold-plated copper.

[0044] In some embodiments, the second electrode tab 3 is made of a conductive material, such as copper, aluminum, nickel, nickel-plated copper, tin-plated copper, or gold-plated copper.

[0045] In some embodiments, the first electrode tab 2 and the second electrode tab 3 may be welded by any one of ultrasonic welding, laser welding, resistance welding, soft soldering, brazing, pulse welding, friction welding, and cold pressure welding.

[0046] In some embodiments, the area of ​​the first tab 2 and the second tab 3 when welded is ≥50mm 2 If the welding range is too small, the welding tension may be too small, resulting in welding failure.

[0047] In some embodiments, the power during welding of the first electrode tab 2 and the second electrode tab 3 is 500W-3000W.

[0048] According to the second aspect of the present application, the present application provides a secondary battery comprising a battery cell and an electrolyte, wherein the battery cell comprises a positive electrode sheet, a negative electrode sheet, a separator separated between the positive electrode sheet and the negative electrode sheet, and the above-mentioned battery cell tab connection structure.

[0049] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material. The positive electrode active material may include but is not limited to a chemical formula such as Li a Ni x Co y M z O 2-b N b (wherein 0.95≤a≤1.2, x>0, y≥0, z≥0, and x+y+z=1, 0≤b≤1, M is selected from a combination of one or more of Mn and Al, and N is selected from a combination of one or more of F, P, and S), the positive electrode active material may also be, but is not limited to, LiCoO2, LiNiO2, LiVO2, LiCrO2, LiMn2O4, LiCoMnO4, Li2NiMn3O8, LiNi 0.5 Mn 1.5 The positive electrode active material may be a combination of one or more of O4, LiCoPO4, LiMnPO4, LiFePO4, LiNiPO4, LiCoFSO4, CuS2, FeS2, MoS2, NiS, TiS2, etc. The positive electrode active material may also be subjected to a modification treatment. Methods for modifying the positive electrode active material should be known to those skilled in the art. For example, the positive electrode active material may be modified by coating, doping, etc. The materials used for the modification treatment may include, but are not limited to, a combination of one or more of Al, B, P, Zr, Si, Ti, Ge, Sn, Mg, Ce, W, etc. The positive electrode current collector is generally a structure or part for collecting current. The positive electrode current collector may be any material suitable for use as a positive electrode current collector for lithium-ion batteries in the art. For example, the positive electrode current collector may include, but is not limited to, metal foil, and more specifically, may include, but is not limited to, aluminum foil.

[0050] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on at least one surface of the negative electrode current collector. The negative electrode active material layer can be one or more materials including but not limited to graphite, soft carbon, hard carbon, carbon fiber, mesophase carbon microbeads, silicon-based materials, tin-based materials, lithium titanate or other metals that can form alloys with lithium.

[0051] Graphite can be selected from one or more of artificial graphite, natural graphite, and modified graphite; silicon-based materials can be selected from one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, and silicon alloys; and tin-based materials can be selected from one or more of elemental tin, tin oxide compounds, and tin alloys. The negative electrode current collector is typically a structure or component that collects current. The negative electrode current collector can be any material suitable for use as a negative electrode current collector in lithium-ion batteries. For example, the negative electrode current collector can include, but is not limited to, metal foil, and more specifically, can include, but is not limited to, copper foil.

[0052] The separator can be made of various materials suitable for lithium-ion battery separators in the art, for example, it can be a combination of one or more materials including but not limited to polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester and natural fiber.

[0053] The lithium-ion battery also includes an electrolyte, which includes an organic solvent, an electrolyte lithium salt, and additives. The electrolyte lithium salt can be LiPF6 and / or LiBOB, as used in high-temperature electrolytes; can also be at least one of LiBF4, LiBOB, and LiPF6, as used in low-temperature electrolytes; can also be at least one of LiBF4, LiBOB, LiPF6, and LiTFSI, as used in overcharge-preventing electrolytes; or can be at least one of LiClO4, LiAsF6, LiCF3SO3, and LiN(CF3SO2)2. The organic solvent can be a cyclic carbonate, including PC and EC; a chain carbonate, including DFC, DMC, or EMC; or a carboxylic acid ester, including MF, MA, EA, and MP. Additives include, but are not limited to, at least one of a film-forming additive, a conductive additive, a flame retardant additive, an overcharge prevention additive, an additive to control the H2O and HF content in the electrolyte, an additive to improve low-temperature performance, and a multifunctional additive.

[0054] Based on the disclosure and teachings of the above description, those skilled in the art will be able to make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments described above. Any obvious improvements, substitutions, or modifications made by those skilled in the art based on the present invention fall within the scope of protection of the present invention. In addition, although certain specific terms are used in this description, these terms are for convenience only and do not constitute any limitation on the present invention.

Claims

1. A battery cell tab connection structure, It is characterized by including: Battery cell body; a first electrode tab, wherein one end of the first electrode tab is electrically connected to at least one end of the battery cell body, and the other end of the first electrode tab is divided into N parts along the thickness direction, where N is greater than or equal to 2; The second tab includes a welding end and an external connection end, wherein the welding end is cut into N parts along the thickness direction; The N first electrode tabs and the N second electrode tabs are welded and connected in a one-to-one correspondence.

2. The battery cell tab connection structure according to claim 1, characterized in that: The other end of the first electrode tab is divided into N equal parts along the thickness direction, and the welding end of the second electrode tab is cut into N equal parts along the thickness direction.

3. The battery cell tab connection structure according to claim 1, wherein: A packaging area is further provided between the welding end and the external connection end. The packaging area is provided with tab glue. The distance between the lower edge of the tab glue and the upper edge of the welding end is h, where h satisfies the relationship: 3mm≤h≤8mm.

4. The battery cell tab connection structure according to claim 1, wherein: The total thickness of the first electrode tab is 300-2000 μm.

5. The battery cell tab connection structure according to claim 1, characterized in that: The total thickness of the second electrode tab is 300-2000 μm.

6. The battery cell tab connection structure according to claim 1, characterized in that: The thickness of each of the first electrode tabs is 100-200 μm.

7. The battery cell tab connection structure according to claim 1, characterized in that: The thickness of each of the second electrode tabs is 100-200 μm.

8. The battery cell tab connection structure according to claim 1, characterized in that: The width of the first electrode tab is 10-500 mm.

9. The battery cell tab connection structure according to claim 1, characterized in that: The width of the second electrode tab is 10-500 mm.

10. A secondary battery, characterized in that: The invention comprises the battery cell tab connection structure according to any one of claims 1 to 9.

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