A lithium-ion battery

Abstract

The application provides a lithium ion battery. The application provides a lithium ion battery, which comprises a current collector, the current collector comprises M metal layers and N polymer layers, and the metal layers and the polymer layers are stacked, wherein L metal layers comprise a tab connecting area and a non-tab connecting area, the thickness of the tab connecting area is greater than the thickness of the non-tab connecting area, M is greater than or equal to 1, N is greater than or equal to 1, L is greater than or equal to 1, and M is greater than or equal to L. The application provides a lithium ion battery, the welding strength of a tab is effectively improved by thickening treatment of a tab connecting area on a metal layer for connecting the tab, so that the bonding force between the tab and the current collector is improved, the contact impedance of the tab connecting area is reduced, and the connection yield of the tab and the metal layer is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a lithium ion battery, and relates to the technical field of lithium ion batteries. BACKGROUND

[0002] Due to high energy density and power density, the lithium ion battery is currently a widely used secondary battery. The conventional lithium ion battery current collector adopts a metal foil, the positive electrode usually uses a metal aluminum foil, and the negative electrode usually uses a metal copper foil. Once internal short circuit occurs in the lithium ion battery prepared by directly using the metal foil, the current cannot be cut off in the battery, resulting in heat accumulation and eventually triggering thermal runaway. In order to solve this problem, some researchers use a new type of polymer / metal composite current collector to replace the conventional metal current collector. This type of current collector usually uses an electrically non-conductive polymer film as a substrate, and a layer of metal material is plated on the upper and lower surfaces of the polymer film. For example, metal aluminum is plated on the upper and lower surfaces of the PET (polyethylene terephthalate) film as a positive electrode current collector, and metal copper is plated on the upper and lower surfaces of the PET (polyethylene terephthalate) film as a negative electrode current collector, which has achieved certain effect of improving the safety performance of the battery.

[0003] However, after the above polymer / metal composite current collector is connected with the tab, the bonding force between the tab and the current collector is poor, resulting in high contact resistance of the tab connection area. In addition, the connection yield of the tab connected to the composite current collector is also low, which ultimately affects the performance of the composite current collector and the lithium ion battery. Therefore, how to improve the contact resistance and connection yield of the tab connected to the polymer / metal composite current collector has attracted more and more attention. SUMMARY

[0004] The present application provides a lithium ion battery for solving the problem of high contact resistance and low connection yield of the tab on the existing polymer / metal composite current collector.

[0005] The first aspect of the present application provides a lithium ion battery, comprising a current collector, the current collector comprising M metal layers and N polymer layers, the metal layers and the polymer layers being stacked, wherein L metal layers comprise a tab connection area and a non-tab connection area, the thickness of the tab connection area is greater than the thickness of the non-tab connection area, M is greater than or equal to 1, N is greater than or equal to 1, L is greater than or equal to 1, and M is greater than or equal to L.

[0006] This invention provides a lithium-ion battery, including a current collector. This current collector structure is an improvement on existing composite current collectors. The current collector includes a polymer layer and a metal layer stacked together, with tabs connected to the metal layer. Therefore, the metal layer with tabs is divided into a tab connection region and a non-tab connection region. Those skilled in the art can determine the number of polymer and metal layers and the connection of the tabs according to existing technology and actual manufacturing needs. Subsequently, the metal layer in the tab connection region is thickened, so that the thickness of the metal layer in the final current collector structure is greater than the thickness of the metal layer in the non-tab connection region. Specifically, in the current collector manufacturing process, those skilled in the art can manufacture it according to actual needs and existing processes. For example, a current collector with a uniform metal layer thickness can be prepared first according to existing technology, and then the metal layer in the tab connection region can be thickened using conventional evaporation, sputtering, or electroplating methods. Alternatively, an area with the same area as the tab connection region can be reserved on the polymer layer first, and then a metal layer of the corresponding thickness can be directly disposed in the reserved area. Both methods can yield the current collector structure provided in this application. This invention does not further limit the manufacturing method. This invention provides a current collector that effectively improves the welding strength of the electrode by thickening the electrode connection area on the metal layer, thereby improving the bonding force between the electrode and the current collector, reducing the contact resistance of the electrode connection area, and improving the connection yield between the electrode and the metal layer.

[0007] This invention is applicable to various current collector structures, which are described in detail below:

[0008] In one specific embodiment, the current collector includes the polymer layer and the metal layer disposed on the upper or lower surface of the polymer layer.

[0009] Figure 1 This is a schematic diagram of a current collector structure provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the current collector provided in this embodiment includes a polymer layer 1 and a metal layer 2. The metal layer 2 is disposed on the upper surface of the polymer layer 1, and the metal layer 2 includes a tab connection region away from the upper surface of the polymer layer 1. Figure 1 Short and medium lines The part outlined in the box (the same applies below) and the non-electrode connection area ( Figure 1 Midpoint (The part outlined in the box, the same below) is connected to the electrode 3 and the electrode connection area, i.e., N=M=L=1.

[0010] In another specific embodiment, the current collector includes at least one unit, the unit including the polymer layer and a first metal layer disposed on the upper surface of the polymer layer and a second metal layer disposed on the lower surface of the polymer layer, wherein the first metal layer and / or the second metal layer in at least one unit includes a tab connection region and a non-tab connection region.

[0011] Figure 2 The schematic diagram of the current collector structure provided by another embodiment of the present application is shown in Figure 2 The current collector provided by the embodiment includes one polymer layer 1 and two metal layers, the two metal layers are a first metal layer 2-1 arranged on the upper surface of the polymer layer 1 and a second metal layer 2-2 arranged on the lower surface of the polymer layer 1, the upper surface of the first metal layer 2-1 away from the polymer layer 1 includes a tab connecting area and a non-tab connecting area, and the tab 3 is connected to the tab connecting area, i.e. N = L = 1, M = 2.

[0012] Figure 3 The schematic diagram of the current collector structure provided by another embodiment of the present application is shown in Figure 3 The current collector provided by the embodiment includes one polymer layer 1 and two metal layers, the two metal layers are a first metal layer 2-1 arranged on the upper surface of the polymer layer 1 and a second metal layer 2-2 arranged on the lower surface of the polymer layer 1, the upper surface of the first metal layer 2-1 away from the polymer layer 1 and the lower surface of the second metal layer 2-2 away from the polymer layer 1 both include a tab connecting area and a non-tab connecting area, and the tab connecting areas on the first metal layer 2-1 and the second metal layer 2-2 are both connected to the tab 3, i.e. N = 1, M = L = 2.

[0013] The current collector structure provided by the present application is also applicable to the current collector structure of multiple units, Figure 4 The schematic diagram of the current collector structure provided by another embodiment of the present application is shown in Figure 4 The current collector provided by the embodiment includes X units, X ≥ 2, each unit includes one polymer layer 1 and two metal layers, the two metal layers are a first metal layer 2-1 arranged on the upper surface of the polymer layer 1 and a second metal layer 2-2 arranged on the lower surface of the polymer layer 1, and the upper surface of the first metal layer 2-1 in the first unit includes a tab connecting area and a non-tab connecting area, and the tab 3 is connected to the tab connecting area, i.e. M ≥ 2, N ≥ 2, L = 1.

[0014] It can be understood that, Figure 4 Only the first unit and the Xth unit in the current collector structure are shown, and the repeated units (i.e. the repeated units both include the polymer layer 1, the first metal layer 2-1 and the second metal layer 2-2) are omitted; the active material layer is coated on the surface of the first metal layer and the second metal layer away from the polymer layer in each unit, and if the metal layer includes a tab connecting area and a non-tab connecting area, the active material layer should be coated on the non-tab connecting area, which can be set by those skilled in the art according to the prior art, and the present application will not be described here.

[0015] The number and connection position of the tabs can be set by those skilled in the art according to actual needs, and the tab connection area on the metal layer of the tab can be thickened, and the present application will not be listed in detail.

[0016] When the current collector includes two or more units, the applicant further finds that the connection between the units also has the problem of low connection yield and high contact resistance, which is similar to the connection of the tab. The thickening method of the metal layer of the tab connection area is also applicable to the connection of the metal layer between the units. Those skilled in the art can thicken the metal layer connection area on a metal layer for connecting with another metal layer according to actual needs, that is, a metal layer includes a metal layer connection area and a non-metal layer connection area, the metal layer connection area is used for connecting with the metal layer in another unit, to obtain a multi-unit current collector structure, and the thickness of the metal layer of the metal layer connection area is greater than the thickness of the metal layer of the non-metal layer connection area. In addition, it should be noted that, since the connection of the metal layer between the units involves the metal layer in the upper unit and the metal layer in the lower unit, both the metal layers can be thickened during actual preparation, or only one side of the metal layer can be thickened, and the number of the metal layers thickened by the present application is not limited.

[0017] In a specific embodiment, the current collector includes X units, wherein the first metal layer and / or the second metal layer in Z units include the tab connection area and the non-tab connection area, and the first metal layer and / or the second metal layer in at least one of the remaining (X-Z) units include the metal layer connection area and the non-metal layer connection area, wherein the thickness of the metal layer connection area is greater than the thickness of the non-metal layer connection area, X≥2, and Z≥1.

[0018] Figure 5 The current collector structure provided by another embodiment of the present application is shown in the schematic diagram as shown in Figure 5 The current collector provided by the present embodiment includes X units, X≥2, and each unit includes a polymer layer 1 and two metal layers, i.e., a first metal layer 2-1 arranged on the upper surface of the polymer layer 1 and a second metal layer 2-2 arranged on the lower surface of the polymer layer 1. The first metal layer 2-1 in the first unit away from the upper surface of the polymer layer 1 includes a tab connection area and a non-tab connection area, and a tab 3 is connected to the tab connection area. The first metal layer 2-1 and / or the second metal layer 2-2 in at least one of the second unit to the Xth unit away from the surface of the polymer layer includes a metal layer connection area and a non-metal layer connection area, wherein, Figure 5 only the metal layer connection area (the long dashed line in Figure 5 the boxed part, the same below) and the non-metal layer connection area (the long dashed line in Figure 5 ​The part highlighted in the Chinese text (the same applies below) is Z = 1.

[0019] In another specific embodiment, the current collector includes X units, at least one of the first metal layer and the second metal layer of the Z units includes the tab connection region and the non-tab connection region, and the other of the first metal layer and the second metal layer includes a metal layer connection region and a non-metal layer connection region, wherein the thickness of the metal layer connection region is greater than the thickness of the non-metal layer connection region, X≥2, Z≥1.

[0020] Figure 6 This is a schematic diagram of a current collector structure provided in another embodiment of the present invention, as shown below. Figure 6 As shown, the current collector provided in this embodiment includes X units, where X ≥ 2. Each unit includes a polymer layer 1 and two metal layers. The metal layers are a first metal layer 2-1 disposed on the upper surface of the polymer layer 1 and a second metal layer 2-2 disposed on the lower surface of the polymer layer 1. The surfaces of the first metal layer 2-1 in the first unit and the second metal layer 2-2 in the Xth unit away from the polymer layer 1 include a tab connection region and a non-tab connection region. At the same time, the surfaces of the second metal layer 2-2 in the first unit and the first metal layer 2-1 in the Xth unit away from the polymer layer 1 include a metal connection region and a non-metal connection region, where Z = 2.

[0021] Figure 7 This is a schematic diagram of a current collector structure provided in another embodiment of the present invention, as shown below. Figure 7 As shown, the current collector provided in this embodiment includes X units, where X≥2. Each unit includes a polymer layer 1 and two metal layers. The metal layers are a first metal layer 2-1 disposed on the upper surface of the polymer layer 1 and a second metal layer 2-2 disposed on the lower surface of the polymer layer 1. The surfaces of the first metal layer 2-1, the second metal layer 2-2 in the first unit and the second metal layer 2-2 in the Xth unit that are away from the polymer layer 1 all include a tab connection region and a non-tab connection region. Meanwhile, the surface of the first metal layer 2-1 in the Xth unit that is away from the polymer layer 1 includes a metal layer connection region and a non-metal layer connection region, where Z=1.

[0022] In another specific embodiment, the current collector comprises X units, where X ≥ 2. The first metal layer and / or the second metal layer in Z units include the tab connection region and the non-tab connection region. In at least one of the first and second metal layers in the Z units, one includes the tab connection region and the non-tab connection region, and the other includes a metal layer connection region and a non-metal layer connection region. Meanwhile, in at least one of the remaining XZ units, the first metal layer and / or the second metal layer includes a metal layer connection region and a non-metal layer connection region, wherein the thickness of the metal layer connection region is greater than the thickness of the non-metal layer connection region, where Z ≥ 1.

[0023] Figure 8 This is a schematic diagram of a current collector structure provided in another embodiment of the present invention, as shown below. Figure 8 As shown, the current collector provided in this embodiment includes X units, where X ≥ 2. Each unit includes a polymer layer 1 and two metal layers. The metal layers are a first metal layer 2-1 disposed on the upper surface of the polymer layer 1 and a second metal layer 2-2 disposed on the lower surface of the polymer layer 1. The upper surface of the first metal layer 2-1 in the first unit includes a tab connection region and a non-tab connection region. The surface of the second metal layer 2-2 in the first unit away from the polymer layer 1 includes a metal layer connection region and a non-metal layer connection region. Simultaneously, the surfaces of the first metal layer 2-1 and / or the second metal layer 2-2 in at least one of the units from the second to the Xth unit also include a metal layer connection region and a non-metal layer connection region. Figure 8 Only the metal layer connection region and non-metal layer connection region of the first metal layer 2-1 and the second metal layer 2-2 in the Xth unit are shown, i.e., Z=1.

[0024] The applicant further discovered that the difference in thickness between the tab connection area and the non-tab connection area on the metal layer also has a certain impact on the current collector performance. Specifically, the thickness of the metal layer in the tab connection area is 1.05-10 times the thickness of the metal layer in the non-tab connection area.

[0025] Furthermore, the thickness of the metal layer in the tab connection area is 1.5-3 times the thickness of the metal layer in the non-tab connection area.

[0026] Similar to the effect of the thickness difference between the tab connection area and the non-tab connection area, the thickness difference between the metal layer connection area and the non-metal layer connection area also has a certain impact on the current collector performance. Specifically, the metal layer thickness of the metal layer connection area is 1.05-10 times the metal layer thickness of the non-metal layer connection area.

[0027] The current collector structure provided in this application effectively improves the welding strength between the electrode tab and the current collector. Specifically, the welding strength of the electrode tab is greater than or equal to 0.4 N / mm.

[0028] In summary, the application provides a current collector, by thickening the tab connecting area on the metal layer for connecting the tab, effectively improving the welding strength of the tab, thereby improving the bonding force of the tab and the current collector, reducing the contact resistance of the tab connecting area, and improving the connection yield of the tab and the metal layer.

[0029] On the basis of the current collector provided in the application, a person skilled in the art can prepare a positive electrode sheet according to the prior art, and prepare a lithium ion battery by matching the negative electrode sheet, the separator, the electrolyte, the tab, etc. The lithium ion battery provided in the application effectively reduces the ohmic impedance of the lithium ion battery and improves the welding yield of the lithium ion battery by using the current collector of the application.

[0030] The implementation of the application has at least the following advantages:

[0031] 1. The application provides a current collector, by thickening the tab connecting area on the metal layer for connecting the tab, effectively improving the welding strength of the tab, thereby improving the bonding force of the tab and the current collector, reducing the contact resistance of the tab connecting area, and improving the connection yield of the tab and the metal layer.

[0032] 2. When the current collector includes multiple units, by thickening the metal layer connecting area on the metal layer for connecting between units, the welding strength between units can be effectively improved, thereby reducing the contact resistance between units of the current collector and improving the connection yield between units of the current collector.

[0033] 3. The lithium ion battery provided in the application effectively reduces the ohmic impedance of the lithium ion battery and improves the welding yield of the lithium ion battery by using the current collector provided in the application. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The current collector structure schematic diagram provided for an embodiment of the application;

[0035] Figure 2 The current collector structure schematic diagram provided for another embodiment of the application;

[0036] Figure 3 The current collector structure schematic diagram provided for another embodiment of the application;

[0037] Figure 4 The current collector structure schematic diagram provided for another embodiment of the application;

[0038] Figure 5 The current collector structure schematic diagram provided for another embodiment of the application;

[0039] Figure 6 The current collector structure schematic diagram provided for another embodiment of the application;

[0040] Figure 7 This is a schematic diagram of a current collector structure provided in another embodiment of the present invention;

[0041] Figure 8 This is a schematic diagram of a current collector structure provided in another embodiment of the present invention. Attached image description:

[0043] 1-Polymer layer; 2-Metal layer; 2-1-First metal layer; 2-2-Second metal layer; 3-Taper. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0045] The positive electrode used in the following examples and comparative examples was purchased from Lianyungang Delixin Electronic Technology Co., Ltd., and the material of the positive electrode is aluminum; the negative electrode was purchased from Lianyungang Delixin Electronic Technology Co., Ltd., and the material of the negative electrode is one of nickel, copper-plated metallic nickel, and stainless steel.

[0046] Ultrasonic welding was performed using the UM-20 ultrasonic metal welding machine from Shenzhen Stergaoneng Electronics Technology Co., Ltd. The welding parameters were: welding power 3000W, welding frequency 20kHz, welding amplitude 40μm, welding time 0.42s, and welding pressure 0.3MPa.

[0047] Laser welding was performed using a ZXL-200W laser welding machine from Dongguan Zhengxin Laser Technology Co., Ltd. The welding parameters were: laser wavelength 1064nm, laser power 200W, pulse frequency 150Hz, and pulse width 10ms.

[0048] Example 1

[0049] The current collector structure provided in this embodiment is as follows: Figure 1 As shown, the polymer layer is PET, the metal layer is aluminum, the thickness of the polymer PET layer is 6μm, the thickness of the metal layer in the non-tab connection area is 1μm, the thickness of the metal layer in the tab connection area is 1.05μm, and the positive tab is welded to the tab connection area of ​​the aluminum metal layer by ultrasonic welding. The thickness of the positive tab is 0.1mm and the width is 6mm.

[0050] The LK-108A type tension tester of LiKong instrument technology Co., Ltd. is used to clamp the tab with a clamp, and then the tab is pulled off from the current collector by the tension tester to test the pulling force value N, the tab width is D, and the tab welding strength F=N / D can be calculated. The results show that the tab welding strength in this embodiment is 0.6 N / mm.

[0051] Example 2

[0052] The current collector structure provided in this embodiment is shown in Figure 1 The polymer layer is PET, the metal layer is aluminum, the thickness of the polymer PET layer is 6 μm, the thickness of the metal layer in the non-tab connecting area is 1 μm, the thickness of the metal layer in the tab connecting area is 1.5 μm, the positive tab is welded on the tab connecting area of the metal aluminum layer by ultrasonic welding, the thickness of the positive tab is 0.1 mm, and the width is 6 mm.

[0053] The same welding strength test method as in Example 1 is used, and the results show that the tab welding strength in this embodiment is 1.1 N / mm.

[0054] Example 3

[0055] The current collector structure provided in this embodiment is shown in Figure 1 The polymer layer is PET, the metal layer is aluminum, the thickness of the polymer PET layer is 6 μm, the thickness of the metal layer in the non-tab connecting area is 1 μm, the thickness of the metal layer in the tab connecting area is 2 μm, the positive tab is welded on the tab connecting area of the metal aluminum layer by ultrasonic welding, the thickness of the positive tab is 0.1 mm, and the width is 6 mm.

[0056] The same welding strength test method as in Example 1 is used, and the results show that the tab welding strength in this embodiment is 1.6 N / mm.

[0057] Example 4

[0058] The current collector structure provided in this embodiment is shown in Figure 1 The polymer layer is PET, the metal layer is aluminum, the thickness of the polymer PET layer is 6 μm, the thickness of the metal layer in the non-tab connecting area is 1 μm, the thickness of the metal layer in the tab connecting area is 3 μm, the positive tab is welded on the tab connecting area of the metal aluminum layer by ultrasonic welding, the thickness of the positive tab is 0.1 mm, and the width is 6 mm.

[0059] The same welding strength test method as in Example 1 is used, and the results show that the tab welding strength in this embodiment is 2.2 N / mm.

[0060] Example 5

[0061] The current collector structure provided in this embodiment is shown in Figure 1As shown in the figure, the polymer layer is PET, the metal layer is aluminum, the thickness of the polymer PET layer is 6 μm, the thickness of the metal layer in the non-tab connecting area is 1 μm, the thickness of the metal layer in the tab connecting area is 5 μm, the positive tab is welded on the tab connecting area of the metal aluminum layer by ultrasonic welding, the thickness of the positive tab is 0.1 mm, and the width of the positive tab is 6 mm.

[0062] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this embodiment was 1.9 N / mm.

[0063] Example 6

[0064] The current collector structure provided in this embodiment is as shown in the figure. Figure 1 As shown in the figure, the polymer layer is PET, the metal layer is copper, the thickness of the polymer PET layer is 6 μm, the thickness of the metal layer in the non-tab connecting area is 1 μm, the thickness of the metal layer in the tab connecting area is 1.05 μm, the negative tab is welded on the tab connecting area of the metal copper layer by ultrasonic welding, the material of the negative tab is nickel, the thickness of the negative tab is 0.1 mm, and the width of the negative tab is 6 mm.

[0065] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this embodiment was 0.4 N / mm.

[0066] Example 7

[0067] The current collector structure provided in this embodiment is as shown in the figure. Figure 1 As shown in the figure, the polymer layer is PET, the metal layer is copper, the thickness of the polymer PET layer is 6 μm, the thickness of the metal layer in the non-tab connecting area is 1 μm, the thickness of the metal layer in the tab connecting area is 1.5 μm, the negative tab is welded on the tab connecting area of the metal copper layer by ultrasonic welding, the material of the negative tab is nickel, the thickness of the negative tab is 0.1 mm, and the width of the negative tab is 6 mm.

[0068] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this embodiment was 0.9 N / mm.

[0069] Example 8

[0070] The current collector structure provided in this embodiment is as shown in the figure. Figure 1 As shown in the figure, the polymer layer is PET, the metal layer is copper, the thickness of the polymer PET layer is 6 μm, the thickness of the metal layer in the non-tab connecting area is 1 μm, the thickness of the metal layer in the tab connecting area is 2 μm, the negative tab is welded on the tab connecting area of the metal copper layer by ultrasonic welding, the material of the negative tab is nickel, the thickness of the negative tab is 0.1 mm, and the width of the negative tab is 6 mm.

[0071] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this example was 1.5 N / mm.

[0072] Example 9

[0073] The current collector structure provided in this example is as shown in Figure 1 wherein the polymer layer is PET, the metal layer is copper, the thickness of the polymer PET layer is 6 μm, the thickness of the metal layer in the non-tab connecting area is 1 μm, the thickness of the metal layer in the tab connecting area is 3 μm, the negative tab is welded on the tab connecting area of the metal copper layer by ultrasonic welding, the material of the negative tab is nickel, the thickness of the negative tab is 0.1 mm, and the width of the negative tab is 6 mm.

[0074] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this example was 2.1 N / mm.

[0075] Example 10

[0076] The current collector structure provided in this example is as shown in Figure 1 wherein the polymer layer is PET, the metal layer is copper, the thickness of the polymer PET layer is 6 μm, the thickness of the metal layer in the non-tab connecting area is 1 μm, the thickness of the metal layer in the tab connecting area is 5 μm, the negative tab is welded on the tab connecting area of the metal copper layer by ultrasonic welding, the material of the negative tab is nickel, the thickness of the negative tab is 0.1 mm, and the width of the negative tab is 6 mm.

[0077] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this example was 1.8 N / mm.

[0078] Example 11

[0079] The current collector structure provided in this example is as shown in Figure 1 wherein the polymer layer is PP, the metal layer is aluminum, the thickness of the polymer PP layer is 4 μm, the thickness of the metal layer in the non-tab connecting area is 0.5 μm, the thickness of the metal layer in the tab connecting area is 5 μm, the positive tab is welded on the tab connecting area of the metal aluminum layer by ultrasonic welding, the thickness of the positive tab is 0.1 mm, and the width of the positive tab is 6 mm.

[0080] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this example was 1.9 N / mm.

[0081] Example 12

[0082] The current collector structure provided in this example is as shown in Figure 1As shown in the figure, the polymer layer is PET, the metal layer is copper, the thickness of the polymer PET layer is 5 μm, the thickness of the metal layer in the non-tab connecting area is 0.5 μm, the thickness of the metal layer in the tab connecting area is 5 μm, the negative tab is welded on the tab connecting area of the metal copper layer by ultrasonic welding, the material of the negative tab is nickel, the thickness of the negative tab is 0.1 mm, and the width of the negative tab is 6 mm.

[0083] The same welding strength test method as in Example 1 is adopted, and the results show that the tab welding strength in this embodiment is 1.7 N / mm.

[0084] Example 13

[0085] The current collector structure provided in this embodiment is as shown in the figure Figure 1 As shown in the figure, the polymer layer is PET, the metal layer is copper, the thickness of the polymer PET layer is 5 μm, the thickness of the metal layer in the non-tab connecting area is 0.5 μm, the thickness of the metal layer in the tab connecting area is 5 μm, the negative tab is welded on the tab connecting area of the metal copper layer by ultrasonic welding, the material of the negative tab is nickel, the thickness of the negative tab is 0.1 mm, and the width of the negative tab is 6 mm.

[0086] The same welding strength test method as in Example 1 is adopted, and the results show that the tab welding strength in this embodiment is 1.7 N / mm.

[0087] Example 14

[0088] The current collector structure provided in this embodiment is as shown in the figure Figure 1 As shown in the figure, the polymer layer is PET, the metal layer is copper, the thickness of the polymer PET layer is 5 μm, the thickness of the metal layer in the non-tab connecting area is 0.5 μm, the thickness of the metal layer in the tab connecting area is 5 μm, the negative tab is welded on the tab connecting area of the metal copper layer by ultrasonic welding, the material of the negative tab is nickel, the thickness of the negative tab is 0.1 mm, and the width of the negative tab is 6 mm.

[0089] The same welding strength test method as in Example 1 is adopted, and the results show that the tab welding strength in this embodiment is 1.7 N / mm.

[0090] Example 15

[0091] The current collector structure provided in this embodiment is as shown in the figure Figure 2 As shown in the figure, the polymer layer is PET, the metal layer is copper, the thickness of the polymer PET layer is 5 μm, the thickness of the metal layer in the non-tab connecting area is 0.5 μm, the thickness of the metal layer in the tab connecting area is 5 μm, the negative tab is welded on the tab connecting area of the metal copper layer by ultrasonic welding, the material of the negative tab is nickel, the thickness of the negative tab is 0.1 mm, and the width of the negative tab is 6 mm.

[0092] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this example was 1.9 N / mm.

[0093] Example 16

[0094] The current collector structure provided in this example is shown in Figure 2 wherein the polymer layer is PP, the metal layer is copper, the thickness of the polymer PP layer is 25 μm, the thickness of the metal layer in the non-tab connecting area is 0.9 μm, the thickness of the metal layer in the tab connecting area is 1.6 μm, the negative tab is welded on the tab connecting area of the metal copper layer by ultrasonic welding, the material of the negative tab is nickel, the thickness of the negative tab is 0.08 mm, and the width of the negative tab is 6 mm.

[0095] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this example was 1.7 N / mm.

[0096] Example 17

[0097] The current collector structure provided in this example is shown in Figure 3 wherein the polymer layer is PP, the metal layer is aluminum, the thickness of the polymer PP layer is 8 μm, the thickness of the metal layer in the non-tab connecting area is 0.7 μm, the thickness of the metal layer in the tab connecting area is 1.2 μm, the positive tab is welded on the tab connecting area of the metal aluminum layer by ultrasonic welding, the thickness of the positive tab is 0.05 mm, and the width of the positive tab is 8 mm.

[0098] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this example was 1.5 N / mm.

[0099] Example 18

[0100] The current collector structure provided in this example is shown in Figure 3 wherein the polymer layer is PP, the metal layer is copper, the thickness of the polymer PP layer is 8 μm, the thickness of the metal layer in the non-tab connecting area is 0.7 μm, the thickness of the metal layer in the tab connecting area is 1.2 μm, the negative tab is welded on the tab connecting area of the metal copper layer by ultrasonic welding, the material of the negative tab is copper-plated nickel, the thickness of the negative tab is 0.05 mm, and the width of the negative tab is 8 mm.

[0101] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this example was 1.5 N / mm.

[0102] Example 19

[0103] The current collector structure provided in this example is shown in Figure 6As shown, X = 9, where the polymer layer is PET, the metal layer is aluminum, the thickness of the polymer PET layer is 9 μm, the thickness of the metal layer in the non-tab connection region and the non-metal layer connection region is 1 μm, and the tab connection region and the metal layer connection region (the metal layer connection region here is set on the metal layer of each layer that does not need to be connected to the tab, i.e.) Figure 6 The metal layer (which is omitted in the text) includes a metal layer connection area and a non-metal layer connection area. In the following embodiments, the metal layer connection area is the same. The thickness of the metal layer is 1.5 μm. The positive electrode tab is welded to the electrode tab connection area of ​​the aluminum metal layer by ultrasonic welding. The thickness of the positive electrode tab is 0.2 mm and the width is 12 mm.

[0104] Using the same welding strength test method as in Example 1, the results show that the electrode lug welding strength in this example is 2.6 N / mm.

[0105] Example 20

[0106] The current collector structure provided in this embodiment is as follows: Figure 6 As shown, X = 10, where the polymer layer is PET, the metal layer is stainless steel, the thickness of the polymer PET layer is 9μm, the thickness of the metal layer in the non-tab connection area and the non-metal layer connection area is 1μm, and the thickness of the metal layer in the tab connection area and the metal layer connection area is 1.5μm. The negative tab is welded to the tab connection area of ​​the stainless steel metal layer by laser welding. The material of the negative tab is stainless steel, the thickness of the negative tab is 0.2mm, and the width is 12mm.

[0107] Using the same welding strength test method as in Example 1, the results show that the welding strength of the electrode lug in this example is 2.4 N / mm.

[0108] Example 21

[0109] The current collector structure provided in this embodiment is as follows: Figure 7 As shown, X = 9, where the polymer layer is PP, the metal layer is aluminum, the thickness of the polymer PP layer is 8μm, the thickness of the metal layer in the non-tab connection area and the non-metal layer connection area is 0.8μm, and the thickness of the metal layer in the tab connection area and the metal layer connection area is 2μm. The positive tab is welded to the tab connection area of ​​the aluminum metal layer by laser welding. The thickness of the positive tab is 0.03mm and the width is 15mm.

[0110] Using the same welding strength test method as in Example 1, the results show that the electrode lug welding strength in this example is 2.9 N / mm.

[0111] Example 22

[0112] The current collector structure provided in this embodiment is as follows: Figure 7As shown in the figure, X = 10, wherein the polymer layer is PP, the metal layer is nickel, the thickness of the polymer PP layer is 8 μm, the thickness of the metal layer in the non-tab connecting area and the non-metal layer connecting area is 0.8 μm, the thickness of the metal layer in the tab connecting area and the metal layer connecting area is 2 μm, the negative tab is welded on the tab connecting area of the metal nickel layer by laser welding, the material of the negative tab is nickel, the thickness of the negative tab is 0.03 mm, and the width of the negative tab is 15 mm;

[0113] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this example was 2.7 N / mm.

[0114] Example 23

[0115] The current collector structure provided in this example is as shown in the figure Figure 8 As shown in the figure, X = 9, wherein the polymer layer is PP, the metal layer is aluminum, the thickness of the polymer PP layer is 8 μm, the thickness of the metal layer in the non-tab connecting area and the non-metal layer connecting area is 0.6 μm, the thickness of the metal layer in the tab connecting area and the metal layer connecting area is 1 μm, the positive tab is welded on the tab connecting area of the metal aluminum layer by ultrasonic welding, the thickness of the positive tab is 1 mm, and the width of the positive tab is 10 mm;

[0116] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this example was 2 N / mm.

[0117] Example 24

[0118] The current collector structure provided in this example is as shown in the figure Figure 8 As shown in the figure, X = 10, wherein the polymer layer is PP, the metal layer is nickel, the thickness of the polymer PP layer is 8 μm, the thickness of the metal layer in the non-tab connecting area and the non-metal layer connecting area is 0.6 μm, the thickness of the metal layer in the tab connecting area and the metal layer connecting area is 1 μm, the negative tab is welded on the tab connecting area of the metal nickel layer by ultrasonic welding, the material of the negative tab is nickel, the thickness of the negative tab is 1 mm, and the width of the negative tab is 10 mm;

[0119] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this example was 1.9 N / mm.

[0120] Comparative Example 1

[0121] The current collector provided in this comparative example includes a polymer layer and a metal layer, and the metal layer is arranged on the upper surface of the polymer layer, wherein the polymer layer is PET, the metal layer is aluminum, the thickness of the polymer PET layer is 6 μm, the thickness of the metal layer is 1 μm, the positive tab is welded on the metal aluminum layer by ultrasonic welding, the thickness of the positive tab is 0.1 mm, and the width of the positive tab is 6 mm;

[0122] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this comparative example was 0.2 N / mm.

[0123] Comparative Example 2

[0124] The current collector provided in this comparative example includes a polymer layer and a metal layer, and the metal layer is disposed on the upper surface of the polymer layer, wherein the polymer layer is PET, the metal layer is copper, the thickness of the polymer PET layer is 6 pm, and the thickness of the metal layer is 1 pm. The negative tab is welded on the metal copper layer by ultrasonic welding, the material of the negative tab is nickel, the thickness of the negative tab is 0.1 mm, and the width of the negative tab is 6 mm.

[0125] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this comparative example was 0.1 N / mm.

[0126] Comparative Example 3

[0127] The current collector provided in this comparative example includes a polymer layer and a metal layer, and the metal layer is disposed on the upper surface and the lower surface of the polymer layer, wherein the polymer layer is PP, the metal layer is aluminum, the thickness of the polymer PET layer is 22 pm, and the thickness of the metal layer is 1.1 pm. The positive tab is welded on the metal aluminum layer on the upper surface of the polymer layer by ultrasonic welding, the thickness of the tab is 0.08 mm, and the width of the tab is 8 mm.

[0128] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this comparative example was 0.3 N / mm.

[0129] Comparative Example 4

[0130] The current collector provided in this comparative example includes a polymer layer and a metal layer, and the metal layer is disposed on the upper surface and the lower surface of the polymer layer, wherein the polymer layer is PP, the metal layer is copper, the thickness of the polymer PET layer is 25 pm, and the thickness of the metal layer is 0.9 pm. The negative tab is welded on the metal copper layer on the upper surface of the polymer layer by ultrasonic welding, the material of the negative tab is nickel, the thickness of the negative tab is 0.08 mm, and the width of the negative tab is 6 mm.

[0131] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this comparative example was 0.2 N / mm.

[0132] Comparative Example 5

[0133] The current collector provided by the comparative example includes a polymer layer and a metal layer, the metal layer is arranged on the upper surface and the lower surface of the polymer layer, wherein the polymer layer is PP, the metal layer is aluminum, the thickness of the polymer PP layer is 8 μm, the thickness of the metal layer is 0.7 μm, the positive tab is welded on the metal aluminum layer on the upper surface and the lower surface of the polymer layer by ultrasonic welding, the thickness of the positive tab is 0.05 mm, and the width of the positive tab is 8 mm.

[0134] The same welding strength test method as in Example 1 is used, and the results show that the tab welding strength in the comparative example is 0.2 N / mm.

[0135] Comparative Example 6

[0136] The current collector provided by the comparative example includes a polymer layer and a metal layer, the metal layer is arranged on the upper surface and the lower surface of the polymer layer, wherein the polymer layer is PP, the metal layer is copper, the thickness of the polymer PP layer is 8 μm, the thickness of the metal layer is 0.7 μm, the negative tab is welded on the metal aluminum layer on the upper surface and the lower surface of the polymer layer by ultrasonic welding, the material of the negative tab is metal nickel plated with copper on the surface, the thickness of the negative tab is 0.05 mm, and the width of the negative tab is 8 mm.

[0137] The same welding strength test method as in Example 1 is used, and the results show that the tab welding strength in the comparative example is 0.2 N / mm.

[0138] Comparative Example 7

[0139] The current collector provided by the comparative example includes 9 units, each unit includes a polymer layer and a metal layer, the metal layer is arranged on the upper surface and the lower surface of the polymer layer; wherein the polymer layer is PP, the metal layer is aluminum, the thickness of the polymer PP layer is 8 μm, the thickness of the metal layer is 0.6 μm, the positive tab is welded on the metal aluminum layer on the upper surface of the polymer layer of the first unit by ultrasonic welding, the thickness of the positive tab is 1 mm, and the width of the positive tab is 10 mm.

[0140] The same welding strength test method as in Example 1 is used, and the results show that the tab welding strength in the comparative example is 0.2 N / mm.

[0141] Comparative Example 8

[0142] The current collector provided by the comparative example includes 10 units, each unit includes a polymer layer and a metal layer, the metal layer is arranged on the upper surface and the lower surface of the polymer layer; wherein the polymer layer is PP, the metal layer is nickel, the thickness of the polymer PP layer is 8 μm, the thickness of the metal layer is 0.6 μm, the negative tab is welded on the metal nickel layer on the upper surface of the polymer layer of the first unit by ultrasonic welding, the material of the negative tab is nickel, the thickness of the tab is 1 mm, and the width of the tab is 10 mm.

[0143] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this comparative example was 0.1 N / mm.

[0144] Comparative Example 9

[0145] The current collector provided in this comparative example included 9 units, each unit including a polymer layer and a metal layer disposed on the upper and lower surfaces of the polymer layer; wherein the polymer layer was PET, the metal layer was aluminum, the thickness of the polymer PET layer was 9 pm, and the thickness of the metal layer was 1 pm. The positive tab was welded on the upper surface of the polymer layer of the first unit and the metal aluminum layer on the lower surface of the polymer layer of the 9th unit by ultrasonic welding, the thickness of the positive tab was 0.2 mm, and the width was 12 mm.

[0146] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this comparative example was 0.3 N / mm.

[0147] Comparative Example 10

[0148] The current collector provided in this comparative example included 10 units, each unit including a polymer layer and a metal layer disposed on the upper and lower surfaces of the polymer layer; wherein the polymer layer was PET, the metal layer was stainless steel, the thickness of the polymer PET layer was 9 pm, and the thickness of the metal layer was 1 pm. The negative tab was welded on the upper surface of the polymer layer of the first unit and the metal stainless steel layer on the lower surface of the polymer layer of the 10th unit by laser welding, the material of the negative tab was stainless steel, the thickness of the negative tab was 0.2 mm, and the width was 12 mm.

[0149] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this comparative example was 0.3 N / mm.

[0150] Comparative Example 11

[0151] The current collector provided in this comparative example included 9 units, each unit including a polymer layer and a metal layer disposed on the upper and lower surfaces of the polymer layer; wherein the polymer layer was PP, the metal layer was aluminum, the thickness of the polymer PP layer was 8 pm, and the thickness of the metal layer was 0.8 pm. The positive tab was welded on the upper surface of the polymer layer of the first unit, the lower surface of the polymer layer of the first unit, and the metal aluminum layer on the lower surface of the polymer layer of the 9th unit by laser welding, the thickness of the positive tab was 0.03 mm, and the width was 15 mm.

[0152] The same welding strength test method as in Example 1 was used, and the results showed that the tab welding strength in this comparative example was 0.3 N / mm.

[0153] Comparative Example 12

[0154] The current collector provided by the comparative example includes 10 units, each unit includes a polymer layer and a metal layer arranged on the upper surface and the lower surface of the polymer layer; wherein the polymer layer is PP, the metal layer is nickel, the thickness of the polymer PP layer is 8 μm, the thickness of the metal layer is 0.8 μm, the negative tab is welded on the metal nickel layer on the upper surface and the lower surface of the first unit polymer layer and the lower surface of the 10th unit polymer layer by laser welding, the material of the negative tab is nickel, the thickness of the negative tab is 0.03 mm, and the width of the negative tab is 15 mm.

[0155] The same welding strength test method as in Example 1 is used, and the results show that the tab welding strength in the comparative example is 0.2 N / mm.

[0156] On the basis of the current collectors provided in the above examples and comparative examples, lithium ion batteries are prepared. In the following examples and comparative examples, the lithium cobaltate positive material is purchased from Beijing Dangsheng Material Technology Co., Ltd., and the specific capacity is 181 mAh / g; the graphite negative material is purchased from Shanghai Sunson Technology Co., Ltd., and the specific capacity is 359 mAh / g.

[0157] The polyethylene (PE) porous separator is a wet-process separator ND12 produced by Shanghai Enxin New Material Technology Co., Ltd., and the thickness is 12 μm; the electrolyte is LBC445B33 type electrolyte from Shenzhen Xinzhubang Technology Co., Ltd.

[0158] Example 25

[0159] 95 parts by mass of lithium cobaltate positive material, 2 parts by mass of acetylene black conductive agent, 0.5 parts by mass of carbon nanotube conductive agent, 2.5 parts by mass of PVDF binder, and 60 parts by mass of solvent NMP are stirred by a double-planetary stirrer under vacuum at a condition of revolution 30 r / min and rotation 1500 r / min for 4 h to disperse into a uniform slurry, which is coated on the current collector provided in Example 1, then dried at 120°C and rolled under a pressure of 40 tons, and cut into a positive tab. The tab surface density of the positive tab is 20 mg / cm 2 , and the compacted density is 4.16 g / cm 3 .

[0160] 95 parts by mass of the graphite negative electrode material, 1.5 parts by mass of acetylene black conductive agent, 0.5 parts by mass of carbon nanotube conductive agent, 2.0 parts by mass of butadiene-styrene rubber (SBR) binder, 1.0 parts by mass of carboxymethyl cellulose (CMC), and 100 parts by mass of solvent water were stirred by a double planetary mixer under vacuum at a condition of 30 r / min in revolution and 1500 r / min in rotation for 4 h, dispersed into a uniform slurry, coated on the current collector provided in Example 6, and then dried at 110°C and roll-pressed under a pressure of 40 tons, and cut into a negative electrode sheet. The sheet surface density of the negative electrode sheet was 10 mg / cm 2 , and the compacted density was 1.74 g / cm 3 .

[0161] The above positive electrode sheet and negative electrode sheet, in combination with a polyethylene (PE) porous separator and an electrolyte, were prepared into a lithium ion battery C1 by a conventional preparation process.

[0162] Example 26

[0163] The lithium ion battery C2 was prepared by using the current collector provided in Example 2 as the positive electrode, the current collector provided in Example 7 as the negative electrode, and the same preparation method as that in Example 25.

[0164] Example 27

[0165] The lithium ion battery C3 was prepared by using the current collector provided in Example 3 as the positive electrode, the current collector provided in Example 8 as the negative electrode, and the same preparation method as that in Example 25.

[0166] Example 28

[0167] The lithium ion battery C4 was prepared by using the current collector provided in Example 4 as the positive electrode, the current collector provided in Example 9 as the negative electrode, and the same preparation method as that in Example 25.

[0168] Example 29

[0169] The lithium ion battery C5 was prepared by using the current collector provided in Example 5 as the positive electrode, the current collector provided in Example 10 as the negative electrode, and the same preparation method as that in Example 25.

[0170] Example 30

[0171] The lithium ion battery C6 was prepared by using the current collector provided in Example 11 as the positive electrode, the current collector provided in Example 12 as the negative electrode, and the same preparation method as that in Example 25.

[0172] Example 31

[0173] A lithium ion battery C7 was prepared using the current collector provided in Example 13 as the positive electrode, the current collector provided in Example 14 as the negative electrode, and using the same preparation method as Example 25.

[0174] Example 32

[0175] A lithium ion battery C8 was prepared using the current collector provided in Example 15 as the positive electrode, the current collector provided in Example 16 as the negative electrode, and using the same preparation method as Example 25.

[0176] Example 33

[0177] A lithium ion battery C9 was prepared using the current collector provided in Example 17 as the positive electrode, the current collector provided in Example 18 as the negative electrode, and using the same preparation method as Example 25.

[0178] Example 34

[0179] A lithium ion battery C10 was prepared using the current collector provided in Example 19 as the positive electrode, the current collector provided in Example 20 as the negative electrode, and using the same preparation method as Example 25.

[0180] Example 35

[0181] A lithium ion battery C11 was prepared using the current collector provided in Example 21 as the positive electrode, the current collector provided in Example 22 as the negative electrode, and using the same preparation method as Example 25.

[0182] Example 36

[0183] A lithium ion battery C12 was prepared using the current collector provided in Example 23 as the positive electrode, the current collector provided in Example 24 as the negative electrode, and using the same preparation method as Example 25.

[0184] Comparative Example 13

[0185] A lithium ion battery Al was prepared using the current collector provided in Comparative Example 1 as the positive electrode, the current collector provided in Comparative Example 2 as the negative electrode, and using the same preparation method as Example 25.

[0186] Comparative Example 14

[0187] A lithium ion battery A2 was prepared using the current collector provided in Comparative Example 3 as the positive electrode, the current collector provided in Comparative Example 4 as the negative electrode, and using the same preparation method as Example 25.

[0188] Comparative Example 15

[0189] A lithium ion battery A3 was prepared by using the current collector provided by Comparative Example 5 as the positive electrode, the current collector provided by Comparative Example 6 as the negative electrode, and the same preparation method as that of Example 25.

[0190] Comparative Example 16

[0191] A lithium ion battery A4 was prepared by using the current collector provided by Comparative Example 7 as the positive electrode, the current collector provided by Comparative Example 8 as the negative electrode, and the same preparation method as that of Example 25.

[0192] Comparative Example 17

[0193] A lithium ion battery A5 was prepared by using the current collector provided by Comparative Example 9 as the positive electrode, the current collector provided by Comparative Example 10 as the negative electrode, and the same preparation method as that of Example 25.

[0194] Comparative Example 18

[0195] A lithium ion battery A6 was prepared by using the current collector provided by Comparative Example 11 as the positive electrode, the current collector provided by Comparative Example 12 as the negative electrode, and the same preparation method as that of Example 25.

[0196] The ohmic resistance and the battery welding yield of the lithium ion batteries C1-C12 prepared in Examples 25-36 and the lithium ion batteries A1-A6 prepared in Comparative Examples 13-18 were further tested, and the results are shown in Table 1.

[0197] The ohmic resistance test method comprises: testing the ohmic resistance of the battery by using an internal resistance tester (RBM-200 intelligent battery internal resistance tester from Shenzhen Chaosisi Technology Co., Ltd.), and the frequency of the alternating current signal is set to 1 KHz.

[0198] The battery welding yield test method comprises: preparing 100 identical lithium ion batteries, and visually inspecting and testing the welding strength of the welding points of each lithium ion battery, requiring that each layer of metal layer is connected together and the metal layer and the external tab are also connected together through visual inspection, and at the same time, the welding strength of each layer of metal layer is required to be not less than 80% of the normal welding strength value through the tension tester, if the visual inspection and the welding strength test of one layer of metal layer do not meet the requirements, the lithium ion battery is considered to be a defective product, the number of good products is counted, and the yield rate = good product number / 100*100%.

[0199] Table 1: Performance test results of lithium ion batteries C1-C12 and A1-A6

[0200] Ohmic impedance (mΩ) Battery weld yield C1 128 98％ C2 123 99％ C3 120 99％ C4 117 99％ C5 124 98％ C6 133 97％ C7 116 99％ C8 127 99％ C9 131 99％ C10 109 98％ C11 118 98％ C12 138 98％ A1 221 68％ A2 205 72％ A3 219 70％ A4 224 69％ A5 207 75％ A6 214 73％

[0201] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A lithium-ion battery, characterized in that, It includes a current collector, a positive tab, and a negative tab. The current collector includes M metal layers and N polymer layers, which are stacked. The metal layers and polymer layers are stacked. The L metal layers include a tab connection region and a non-tab connection region. The thickness of the tab connection region is greater than the thickness of the non-tab connection region. M≥1, N≥1, L≥1, M≥L. The current collector comprises X units, each unit comprising the polymer layer, a first metal layer disposed on the upper surface of the polymer layer, and a second metal layer disposed on the lower surface of the polymer layer. In Z units, the first metal layer and / or the second metal layer comprises the tab connection region and the non-tab connection region. In at least one of the remaining (XZ) units, the first metal layer and / or the second metal layer comprises a metal layer connection region and the non-metal layer connection region. The thickness of the metal layer connection region is greater than the thickness of the non-metal layer connection region, X≥2, Z≥1. The current collector comprises X units, wherein at least one of the first metal layer and the second metal layer of the Z units includes the tab connection region and the non-tab connection region, and the other of the first metal layer and the second metal layer includes a metal layer connection region and a non-metal layer connection region, wherein the thickness of the metal layer connection region is greater than the thickness of the non-metal layer connection region, X≥2, Z≥1; The thickness of the metal layer in the metal layer connection region is 1.05-10 times the thickness of the metal layer in the non-metal layer connection region; The welding strength of the electrode lug is greater than or equal to 0.4 N / mm; The positive electrode tab is welded to the electrode connection area of ​​the metal layer by ultrasonic welding; the negative electrode tab is welded to the electrode connection area of ​​the metal layer by laser welding.

2. The lithium-ion battery according to claim 1, characterized in that, The thickness of the metal layer in the tab connection area is 1.05-10 times the thickness of the metal layer in the non-tab connection area.

3. The lithium-ion battery according to claim 1, characterized in that, The thickness of the metal layer in the tab connection area is 1.5-3 times the thickness of the metal layer in the non-tab connection area.

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