Composite current collectors, electrode sheets, batteries, electrical equipment

Abstract

This application relates to a composite current collector, an electrode sheet, a battery, and an electrical device. The composite current collector comprises an insulating base and a conductive layer. The conductive layers are provided on both sides of the insulating base along the thickness direction of the insulating base. Along a direction perpendicular to the thickness direction of the composite current collector, the composite current collector includes an active material support region and a tab connection region, where the thickness of the insulating base in the tab connection region is smaller than that of the insulating base in the active material support region, and the thickness of the conductive layer in the tab connection region is greater than that of the conductive layer in the active material support region. This technical solution is advantageous for improving the degree of metallization at the edge of the composite current collector, and for improving the overcurrent behavior of the electrode sheet in the tab connection region when a tab is connected to the tab connection region.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority from Chinese Patent Application No. 202311010514.0, filed on August 11, 2023, entitled "Composite Current Collector, Electrode Sheet, Battery, Electrical Device," the entire contents of which are incorporated herein by reference.

[0002] The present application relates to a composite current collector, a pole sheet, a battery, and an electric device. [Background technology]

[0003] Lithium-ion batteries have the advantages of high energy density, high output power, long cycle life, and low environmental pollution, and are therefore widely used in electric vehicles and consumer electronics.

[0004] In conventional lithium-ion batteries, copper foil and aluminum foil are commonly used as current collectors to support and conduct current in lithium-ion batteries. In recent years, the demand for high energy density and thermal runaway prevention in lithium-ion batteries has been increasing, and many studies have focused on the application of composite current collectors. Summary of the Invention

[0005] An object of the present application is to provide a composite current collector, a pole sheet, a battery, and an electric device.

[0006] The embodiment of the present application is implemented as follows.

[0007] In a first aspect, an embodiment of the present application provides a composite current collector, comprising an insulating base and a conductive layer, the conductive layer being provided on both sides of the insulating base along the thickness direction of the insulating base.

[0008] Along a direction perpendicular to the thickness direction of the composite current collector, the composite current collector includes an active material support region and a tab connection region, wherein the thickness of the insulating base in the tab connection region is smaller than the thickness of the insulating base in the active material support region, and the thickness of the conductive layer in the tab connection region is greater than the thickness of the conductive layer in the active material support region.

[0009] In the above technical solution, the thickness of the insulating base in the tab connection region is smaller than that of the insulating base in the active material support region, and the thickness of the conductive layer in the tab connection region is greater than that of the conductive layer in the active material support region, which is advantageous in that it can improve the degree of metallization at the edge of the composite current collector, and thus, when the tab is connected to the tab connection region, it can advantageously improve the overcurrent effect of the pole sheet in the tab connection region.

[0010] In some preferred embodiments, the thickness of the composite current collector is the same at each position, the thickness of the insulating base in the active material support region is D1, the thickness of the insulating base in the tab connection region is D3, and D3 <D1である。

[0011] In the above technical solution, the thickness of the insulating base in the active material supporting region and the thickness of the insulating base in the tab connection region satisfy the above relationship, which is advantageous because it can improve the degree of metallization in the tab connection region of the composite current collector, and thus, when the tab is connected to the tab connection region, it is advantageous because it can improve the overcurrent effect of the pole sheet in the tab connection region.

[0012] In some preferred embodiments, the thickness of the conductive layer in the tab connection region is D4, the thickness of the insulating base in the tab connection region is D3, and the ratio of D4 to D3 is A, where A≧1, preferably 1≦A≦2.

[0013] Because the intermediate layer of a composite current collector is a non-conductive polymer, transition welding using metal is required at the tab welding surface, which increases the welding failure rate and makes the battery prone to failure at high rates. The above technical solution sets the thickness of the conductive layer in the tab connection area and the thickness of the insulating base in the tab connection area to satisfy the above relationship, thereby significantly improving the metallization level in the tab connection area of ​​the composite current collector, meeting the requirements for ultrasonic direct welding, eliminating the need for transition welding of the composite current collector, and greatly expanding the application of the composite current collector. The above technical solution eliminates the need for transition welding and meets the high-rate charge / discharge requirements of batteries, which is advantageous for meeting the thermal runaway requirements of batteries with higher requirements.

[0014] In some preferred embodiments, the thickness of the insulating base in the active material support region is D1, the thickness of the insulating base in the tab connection region is D3, the ratio of D1 to D3 is B, and B≧2.

[0015] In the above technical solution, by controlling the lower limit of the ratio of the thickness of the insulating base in the active material supporting region to the thickness of the insulating base in the tab connecting region within the above range, the overall strength and ductility of the insulating base can be effectively controlled to meet both the manufacturing requirements and the overall mechanical performance requirements of the composite current collector, while maintaining sufficient strength and ductility in the active material supporting region.

[0016] In some preferred embodiments, the insulating base of the active material support region has a thickness D1, where 3 μm≦D1≦10 μm.

[0017] In the above technical solution, by setting the thickness of the insulating base of the active material supporting region within the above range, the composite current collector can have good mechanical properties.

[0018] In some preferred embodiments, the thickness of the conductive layer of the active material support region is D2, where 0.5 μm≦D2≦1.5 μm.

[0019] In the above technical solution, by setting the thickness of the conductive layer of the active material supporting region within the above range, the composite current collector can have good current guiding effect.

[0020] In some preferred embodiments, the thickness of the insulating base in the tab connection region is D3, where D3≦3 μm, and preferably 1.5 μm≦D3≦3 μm.

[0021] In the above technical solution, by setting the thickness of the insulating base in the tab connection area within the above range, it is advantageous to achieve a good degree of metallization in the tab connection area, so that the tab connection area can meet the requirements of ultrasonic direct welding, and the composite current collector can be directly welded without using transition welding.

[0022] In some preferred embodiments, the thickness of the conductive layer in the tab connection region is D4, where D4≧1.5 μm, and preferably 1.5 μm≦D4≦4 μm.

[0023] In the above technical solution, by setting the thickness of the conductive layer in the tab connection region within the above range, it is advantageous to improve the strength performance of the edge of the composite current collector, and reduce the probability of the composite current collector being torn by a roll press in the later process of battery manufacturing.

[0024] In some preferred embodiments, the width of the tab connection region is L1, where L1≧10 mm, and preferably 10 mm≦L1≦40 mm.

[0025] In the above technical solution, by controlling the width of the tab connection area within the above range, not only can the shortest tab requirement for pole sheet welding be met, but also the tab length can be controlled to meet the tab folding space design of the battery and the tab length requirement due to winding.

[0026] In some preferred embodiments, the insulating base is doped with a conductive material.

[0027] Preferably, the conductive material comprises at least one of conductive carbon black, carbon nanotubes, acetylene black, or carbon fibers.

[0028] In some preferred embodiments, the conductive material accounts for 3% to 10% by mass of the insulating base.

[0029] In the above technical solution, by controlling the proportion of conductive material added to the insulating base within the above range, the requirement for increasing the conductivity of welding can be met and the flux effect can be exerted, and the mechanical performance of the insulating base will not be affected by an excessive content.

[0030] In some preferred embodiments, the insulating base material comprises at least one of an organic polymer insulating material, an inorganic insulating material, or a composite material.

[0031] Preferably, the organic polymer insulating material comprises at least one of polyamide, polyethylene terephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate, polyparaphenylene terephthalamide, polyphenylene ether, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, or polycarbonate.

[0032] Preferably, the inorganic insulating material comprises at least one of alumina, silicon carbide, or silica.

[0033] Preferably, the composite material comprises at least one of an epoxy resin glass fiber reinforced composite material or a polyester resin glass fiber reinforced composite material.

[0034] In some preferred embodiments, the material of the conductive layer comprises at least one of a metallic conductive material or a carbon-based conductive material.

[0035] Preferably, the metallic conductive material comprises at least one of aluminum, copper, nickel, titanium, silver, a nickel-copper alloy, or an aluminum-zirconium alloy.

[0036] Preferably, the carbon-based conductive material includes at least one of graphite, acetylene black, graphene, or carbon nanotubes.

[0037] In a second aspect, the present embodiment provides a pole sheet including the composite current collector according to the first aspect.

[0038] In the above technical solution, the electrode sheet is provided with the composite current collector according to aspect 1, which can improve the manufacturing yield of the electrode sheet, and can be applied to a battery to improve the cycle performance and energy density of the battery.

[0039] In a third aspect, the present invention provides a battery including the electrode sheet according to the second aspect.

[0040] In the above technical solution, the battery is provided with the electrode sheet according to aspect 2, which is advantageous in that the battery can obtain a high energy density, meet the requirements for high-rate strong charging, and reduce the probability of thermal runaway.

[0041] In a fourth aspect, the present embodiment provides an electrical device including the battery according to the third aspect. [Brief explanation of the drawings]

[0042] In order to more clearly explain the technical solutions of the embodiments of the present application, the following will briefly describe the drawings necessary for the embodiments. It should be understood that the following drawings only illustrate some embodiments of the present application, and should not be considered as limiting the scope, and those skilled in the art can obtain other related drawings based on these drawings without paying creative labor.

[0043] [Figure 1] 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application. [Figure 2] FIG. 1 is an exploded view of a battery according to some embodiments of the present application. [Figure 3] FIG. 3 is an exploded view of the battery cell shown in FIG. [Figure 4] 1 is a partial structural schematic diagram of an electrode assembly according to some embodiments of the present application; [Figure 5] FIG. 2 is a partial structural schematic diagram of a positive electrode sheet according to some examples of the present application. [Figure 6] 1 is a structural schematic diagram of a composite current collector according to some examples of the present application. FIG. [Figure 7] FIG. 2 is another structural schematic diagram of a composite current collector according to some embodiments of the present application. [Figure 8] 1 is a structural schematic diagram of a die for manufacturing an insulating base according to some embodiments of the present application; [Figure 9] 1 is a structural schematic diagram of an edge thinning device for producing an insulating base of a composite current collector according to some embodiments of the present application; FIG. [Figure 10] 2 is a structural schematic diagram of a positive electrode active material coating layer of a composite current collector according to some examples of the present application. FIG.

[0044] (Explanation of symbols) Vehicle 1000, battery 100, controller 200, motor 300, casing 10, first section 11, second section 12, storage space 13, battery cell 20, housing 21, electrode assembly 22, electrode terminal 23, relief structure 24, case 211, lid 212, positive electrode sheet 221, negative electrode sheet 222, separator 223, positive electrode current collector 2211, positive electrode active material layer 2212, negative electrode current collector 2221, negative electrode active material layer 2222 DETAILED DESCRIPTION OF THE INVENTION

[0045] The following detailed description will be given of the embodiments of the technical solution of the present application with reference to the drawings. The following embodiments are merely for the purpose of more clearly explaining the technical solution of the present application, and are merely illustrative and do not limit the scope of protection of the present application.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. The terms used herein are merely for the purpose of describing specific examples and are not intended to limit the present application. The terms "including" and "having" and any variations thereof in the specification, claims, and description of the drawings of this application are intended to cover a non-exclusive "inclusion."

[0047] In describing the embodiments of the present application, the technical terms "first" and "second" are merely used to distinguish between different objects and should not be understood as expressing or implying relative importance, or implying the number, specific order, or superior-subordinate relationship of the technical features shown.

[0048] In the description of the embodiments of the present application, the orientations or positional relationships indicated by technical terms such as "inside" and "outside" are based on the drawings and are intended merely to facilitate explanation of the embodiments of the present application and simplify the description. They do not expressly or imply that the devices or elements described necessarily have a specific orientation or are configured or operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present application.

[0049] In the description of the embodiments of the present application, unless otherwise clearly specified or limited, the technical terms "attach," "connect," "connect," "fixed," etc. should be understood in a broad sense, and may refer to, for example, a fixed connection, a detachable connection, an integral connection, a direct connection, or an indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present application according to specific circumstances.

[0050] The term "embodiment" as referred to herein means that a particular feature, structure, or characteristic described with reference to the embodiment may be included in at least one embodiment of the present application. Terms appearing in various places in the specification do not necessarily refer to the same embodiment, nor are they exclusive, independent, or alternative embodiments to other embodiments. Those skilled in the art can clearly or implicitly understand that the embodiments described herein can be combined with other embodiments.

[0051] In the embodiments of the present application, the same reference numerals indicate the same elements, and for the sake of brevity, detailed descriptions of the same elements in different embodiments will be omitted. It should be understood that the height, length, width, etc. of each element in the embodiments of the present application shown in the drawings, and the overall height, length, width, etc. of the stacking device are merely illustrative and do not limit the present application in any way.

[0052] The composite current collector generally comprises a non-conductive polymer in the middle layer and a metal conductor on the surface layer, where the non-conductive polymer serves as structural support, and the metal conductor provides electrons to the electrode active material and connects the tabs, i.e., it serves as a current-conducting and current-collecting element and a current-carrying element for the pole sheet in the tab area.

[0053] However, the application of composite current collectors is limited by the inclusion of an intermediate layer that is a non-conductive polymer. Studies have shown that the non-conductive nature of the polymer results in a low degree of metallization in the tab connection areas at the edges of the composite current collector, reducing the overcurrent behavior of the composite current collector.

[0054] An embodiment of the present application provides a composite current collector, comprising an insulating base and a conductive layer, the conductive layer being disposed on both sides of the insulating base along the thickness direction of the insulating base.

[0055] Along a direction perpendicular to the thickness direction of the composite current collector, the composite current collector includes an active material support region and a tab connection region, wherein the thickness of the insulating base in the tab connection region is smaller than the thickness of the insulating base in the active material support region, and the thickness of the conductive layer in the tab connection region is greater than the thickness of the conductive layer in the active material support region.

[0056] In the above technical solution, the thickness of the insulating base in the tab connection region is smaller than that of the insulating base in the active material support region, and the thickness of the conductive layer in the tab connection region is greater than that of the conductive layer in the active material support region, which is advantageous for improving the degree of metallization of the edge of the composite current collector, and thus for improving the overcurrent effect of the pole sheet in the tab connection region when the tab is connected to the tab connection region.

[0057] The electrode sheet according to the present application includes the composite current collector described above.

[0058] By providing the electrode sheet with the composite current collector according to aspect 1, the manufacturing yield of the electrode sheet can be increased, and when this is applied to a battery, it contributes to improving the cycle performance and energy density of the battery.

[0059] The battery according to the present application includes the above-described electrode sheet, and by providing the electrode sheet according to aspect 2, the battery is advantageous in that it can achieve a high energy density, meet the requirements for high-rate strong charging, and reduce the probability of thermal runaway.

[0060] An electrical device according to an embodiment of the present application includes the battery described above.

[0061] Referring to FIG. 1, FIG. 1 is a structural schematic diagram of a vehicle 1000 according to some embodiments of the present application. The vehicle 1000 may be a fuel-powered vehicle, a gas-powered vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, a range-extended vehicle, etc. A battery 100 is provided inside the vehicle 1000, and may be provided at the bottom, front, or rear of the vehicle 1000. The battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source for the vehicle 1000. The vehicle 1000 may include a controller 200 and a motor 300, and the controller 200 is used to control the power supply of the battery 100 to the motor 300, for example, for starting, navigation, and operating power needs during driving of the vehicle 1000.

[0062] In some embodiments of the present application, the battery 100 may not only serve as the operating power source for the vehicle 1000, but may also provide the driving force for the vehicle 1000, replacing or partially replacing fuel oil or natural gas.

[0063] In this application, a battery 100 refers to a single physical module that includes one or more battery cells 20 and provides voltage and capacity. The battery 100 generally includes a housing 10 for packaging the one or more battery cells 20. The housing 10 can prevent liquids and other foreign objects from affecting the charging and discharging of the battery cells 20.

[0064] Referring to FIG. 2, FIG. 2 is an exploded view of a battery 100 according to some embodiments of the present application. The battery 100 may include a housing 10 and battery cells 20, and the battery cells 20 are housed in the housing 10. The housing 10 is used to house the battery cells 20, and the housing 10 may have a variety of structures. In some embodiments, the housing 10 may include a first part 11 and a second part 12 that fit together, and the first part 11 and the second part 12 collectively define a housing space 13 for housing the battery cells 20. The second part 12 may have a hollow structure with one end open, the first part 11 having a plate-like structure, and the first part 11 is fitted to the open side of the second part 12 to form the housing 10 having the storage space 13, and both the first part 11 and the second part 12 may have a hollow structure with one end open, and the open side of the first part 11 is fitted to the open side of the second part 12 to form the housing 10 having the storage space 13. Naturally, the first part 11 and the second part 12 may have various shapes such as a cylindrical body or a rectangular parallelepiped.

[0065] The battery 100 may have one or more battery cells 20. When there are multiple battery cells 20, the multiple battery cells 20 may be connected in series, in parallel, or in a composite connection. A composite connection means that the multiple battery cells 20 are connected not only in series but also in parallel. The multiple battery cells 20 may be connected in direct, in parallel, or in a composite connection, and the entire configuration of the multiple battery cells 20 may be housed within the housing 10. The multiple battery cells 20 may be connected in series, in parallel, or in a composite connection to form a battery module, and the multiple battery modules may then be further connected in series, in parallel, or in a composite connection to form a whole and housed within the housing 10. The battery 100 may further include other structures. For example, the multiple battery cells 20 may be electrically connected by bus bars, thereby realizing parallel, series, or composite connections of the multiple battery cells 20.

[0066] Among them, each battery cell 20 may be a lithium ion battery such as a secondary battery or a primary battery, or may be a lithium sulfur battery, a sodium ion battery, or a magnesium ion battery, but is not limited thereto.

[0067] 3, which is an exploded view of the battery cell 20 shown in FIG. 2. The battery cell 20 refers to the smallest unit that constitutes the battery 100. The battery cell 20 includes a housing 21, an electrode assembly 22, and an electrolyte, and both the electrode assembly 22 and the electrolyte are housed within the housing 21.

[0068] The housing 21 may include a case 211 and a lid 212. The case 211 is an assembly that, together with the lid 212, forms an internal sealed space for the battery cell 20. The formed sealed space is used to accommodate the electrode assembly 22, an electrolyte, and other components. The lid 212 is a member that fits over the opening of the case 211 to isolate the internal environment of the battery cell 20 from the external environment, and the shape of the lid 212 is adapted to fit the case 211. The lid 212 may further be provided with functional components such as an electrode terminal 23 and a relief structure 24. A seal ring may be provided between the opening of the case 211 and the lid 212 to achieve a seal between the case 211 and the lid 212.

[0069] The case 211 and the lid 212 may have various shapes and dimensions, such as a rectangular parallelepiped, a cylindrical shape, or a hexagonal prism. Specifically, the shapes of the case 211 and the lid 212 can be determined depending on the specific shape and dimensions of the electrode assembly 22. The case 211 and the lid 212 may be made of a variety of materials, including, but not limited to, metals such as copper, iron, aluminum, stainless steel, and aluminum alloys. The seal ring may be made of a variety of materials, including, but not limited to, materials that are resistant to electrolyte corrosion, highly tough, and fatigue-resistant, such as polypropylene (PP), polycarbonate (PC), and polyethylene terephthalate (PET). A plating layer may be formed on the outer surface of the case 211, and the plating layer may be made of a variety of materials, including, but not limited to, corrosion-resistant materials such as Ni and Cr.

[0070] 4, the electrode assembly 22 may be composed of a positive electrode sheet 221, a negative electrode sheet 222, and a separator 223. The separator 223 is positioned between the positive electrode sheet 221 and the negative electrode sheet 222 to separate them. The electrode assembly 22 may have a wound structure or a stacked structure, and the present application is not limited thereto.

[0071] 5, the negative electrode sheet 222 includes a negative electrode current collector 2221 and a negative electrode active material layer 2222. The negative electrode active material layer 2222 includes a negative electrode active material. The negative electrode active material includes at least one of graphite, silicon, a silicon alloy, and a tin alloy.

[0072] 5, the positive electrode sheet 221 includes a positive electrode current collector 2211 and a positive electrode active material layer 2212. The positive electrode active material layer 2212 includes a positive electrode active material.

[0073] In some embodiments of the present application, the negative electrode current collector 2221 and the positive electrode current collector 2211 can both be selected as composite current collectors.

[0074] In some embodiments of the present application, a composite current collector includes an insulating base and a conductive layer, wherein the conductive layers are disposed on both sides of the insulating base along a thickness direction of the insulating base, and the composite current collector includes an active material support region and a tab connection region along a direction perpendicular to the thickness direction of the composite current collector, wherein the thickness of the insulating base in the tab connection region is smaller than the thickness of the insulating base in the active material support region, and the thickness of the conductive layer in the tab connection region is greater than the thickness of the conductive layer in the active material support region.

[0075] In the above technical solution, the thickness of the insulating base in the tab connection region is smaller than that of the insulating base in the active material support region, and the thickness of the conductive layer in the tab connection region is greater than that of the conductive layer in the active material support region, which is more advantageous for improving the degree of metallization of the edge of the composite current collector, and thus, when the tab is connected to the tab connection region, it is advantageous for improving the overcurrent effect of the pole sheet in the tab connection region.

[0076] Furthermore, in some embodiments of the present application, the tab connection region refers to a region of the composite current collector for connecting a tab, for example, the region of the current collector that is occupied by a tab when the tab is welded to the composite current collector. More preferably, the tab connection region may be provided on one edge of the composite current collector or on both edges of the composite current collector.

[0077] 10, in some embodiments of the present application, the active material support region refers to a region coated with an active material layer, and may be, for example, a region coated with a positive electrode active material layer or a region coated with a negative electrode active material layer. More preferably, the active material support region is provided in the middle region of the composite current collector.

[0078] Furthermore, in some embodiments of the present application, the "thickness of the insulating base of the tab connection region" refers to the thickness of the region when the cross-sectional shape is regular (the thickness is the same at each position within the region), and refers to the average thickness of the entire region when the cross-sectional shape is irregular (the thickness is not exactly the same at each position within the region, or the thickness varies gradually at each position within the region). The "thicknesses" of the other regions described above also follow the same rules. For example, when the cross-sectional shape is irregular, the "thickness of the conductive layer of the tab connection region" refers to the average thickness of the region.

[0079] Further, referring to FIG. 6, in some embodiments of the present application, the thickness of each position of the composite current collector is the same, the thickness of the insulating base in the active material support region (region H in FIG. 6) is D1, the thickness of the insulating base in the tab connection region (region J in FIG. 6) is D3, and D3 <D1である。

[0080] In the above technical solution, the thickness of the insulating base in the active material supporting region and the thickness of the insulating base in the tab connecting region satisfy the above relationship, which is advantageous to improve the degree of metallization in the tab connecting region of the composite current collector, so that when the tab is connected to the tab connecting region, the overcurrent effect of the pole sheet in the tab connecting region is improved.

[0081] Furthermore, conventional composite current collectors typically feature an integrated polymer support layer, with the conductive layer and polymer support layer having uniform thicknesses in both the active material-bearing and tab regions. The support layer is typically thicker than the conductive layer. Because the base film of the support layer in the edge tab region is an insulator, conventional ultrasonic direct welding cannot weld the upper and lower conductive layers together. Instead, two transition metal foils must be welded to the upper and lower conductive layers, respectively, before finally performing multi-layer ultrasonic welding on the electrode sheet tab. However, transition welding poses significant challenges to the reliability of composite current collector welding. If the ultrasonic energy is too low, the metal layers cannot be effectively fused together, resulting in incomplete welding. If the ultrasonic energy is too high, the metal layers are easily destroyed by vibration, which also affects the current-carrying capacity. This type of transition welding not only increases the weld reject rate, but also makes the battery susceptible to high-rate failures.

[0082] In some embodiments of the present application, referring to FIG. 6, the thickness of the conductive layer in the tab connection region is D4, the thickness of the insulating base in the tab connection region is D3, the ratio of D4 to D3 is A, and A≧1.

[0083] The above technical solution significantly improves the metallization degree of the tab connection area of ​​the composite current collector by ensuring that the thickness of the conductive layer in the tab connection area and the thickness of the insulating base in the tab connection area satisfy the above relationship. The commonly used thickness of composite current collectors (3.5 μm to 11.5 μm) meets the requirements for ultrasonic direct welding, eliminating the need for transition welding of the composite current collector and expanding the application of the composite current collector. The above technical solution is advantageous because it eliminates the need for transition welding, significantly reduces the welding failure rate, effectively reduces the probability of failure at high battery rates, and meets the higher requirements for thermal runaway in batteries.

[0084] In other preferred embodiments of the present application, only one side tab may be provided, in which case the composite current collector only provides a tab connection area on one side.

[0085] More preferably, in some embodiments of the present application, 1≦A≦2.

[0086] Illustratively, in some embodiments of the present application, A is 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, or a value within a range formed by any two of the above numbers.

[0087] Further, in some embodiments of the present application, referring to FIG. 6 , the thickness of the insulating base in the active material support region is D1, the thickness of the insulating base in the tab connection region is D3, the ratio of D1 to D3 is B, and B≧2.

[0088] In the above technical solution, by controlling the lower limit of the ratio of the thickness of the insulating base in the active material supporting region to the thickness of the insulating base in the tab connecting region within the above range, the overall strength and ductility of the insulating base can be effectively controlled to meet both the manufacturing requirements and the overall mechanical performance requirements of the composite current collector, while maintaining sufficient strength and ductility in the active material supporting region.

[0089] Furthermore, in some embodiments of the present application, referring to FIG. 6, the thickness of the insulating base of the active material support region is D1, and 3 μm≦D1≦10 μm.

[0090] In the above technical solution, by setting the thickness of the insulating base of the active material supporting region within the above range, the composite current collector can have good mechanical properties.

[0091] Illustratively, in some embodiments of the present application, D1 is 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or a value within a range formed by any two of the above numerical values.

[0092] Furthermore, in some embodiments of the present application, with reference to FIG. 6, the thickness of the conductive layer of the active material support region is D2, and 0.5 μm≦D2≦1.5 μm.

[0093] In the above technical solution, by setting the thickness of the conductive layer of the active material supporting region within the above range, the composite current collector can have good current conductivity effect.

[0094] Illustratively, in some embodiments of the present application, D2 is 0.5 μm, 600 nm, 800 nm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, or a value within a range formed by any two of the above numerical values.

[0095] Furthermore, in some embodiments of the present application, referring to FIG. 6, the thickness of the insulating base in the tab connection region is D3, and D3≦3 μm.

[0096] In the above technical solution, by setting the thickness of the insulating base in the tab connection area within the above range, it is advantageous to achieve a good degree of metallization in the tab connection area, so that the tab connection area can meet the requirements of ultrasonic direct welding, and the composite current collector can be directly welded without using transition welding.

[0097] More preferably, in some embodiments of the present application, 1.5 μm≦D3≦3 μm.

[0098] Illustratively, in some embodiments of the present application, D3 is 1.5 μm, 1.6 μm, 1.8 μm, 2.0 μm, 2.2 μm, 2.3 μm, 2.5 μm, 2.6 μm, 2.8 μm, 3.0 μm, or a value within a range formed by any two of the above numerical values.

[0099] Furthermore, after the composite current collector undergoes the coating process, the welded area is always exposed to the outside and directly contacts the device's drive roller system. Due to the speed difference between the device and the current collector, the boundary between the welded area and the coated area is prone to wear and scratches, damaging and even tearing the submicron conductive layer, increasing the sheet resistance of the electrode sheet and ultimately causing a loss of conductive capability. The above-mentioned incomplete welds and damaged electrode sheets must be removed during the battery manufacturing process, resulting in reduced yield and increased manufacturing costs. If incomplete welds or damaged conductive layers are not recognized during the production process, they are likely to be corroded by the electrolyte after insertion into the battery, resulting in further deterioration of cycle performance and reliability issues. Furthermore, after conventional transition welding, the height of the tab fold of the electrode sheet of the composite current collector is unintentionally increased by approximately 7 mm, significantly reducing the battery's space utilization rate.

[0100] Furthermore, in some embodiments of the present application, referring to FIG. 6, the thickness of the conductive layer in the tab connection region is D4, and D4≧1.5 μm.

[0101] In the above technical solution, the thickness of the conductive layer in the tab connection region is set within the above range, which is advantageous to improve the edge strength performance of the composite current collector, reduce the probability of the composite current collector being torn by roll pressing in the post-processing of the battery, and also reduce the height of the electrode sheet of the composite current collector, thereby improving the space utilization rate of the battery.

[0102] More preferably, in some embodiments of the present application, 1.5 μm≦D4≦4 μm.

[0103] Illustratively, in some embodiments of the present application, D4 is 1.5 μm, 1.8 μm, 2.0 μm, 2.5 μm, 2.8 μm, 3.0 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4.0 μm, or a value within a range formed by any two of the above numerical values.

[0104] Furthermore, in some embodiments of the present application, the thicknesses of the conductive layers provided on both sides of the insulating base may be set to be the same, or the thicknesses of the conductive layers provided on both sides of the insulating base may be set to be different.

[0105] Illustratively, in some embodiments of the present application, the thicknesses D4 of the conductive layers provided in the tab connection regions of the insulating base may be the same, for example, both 1.5 μm, or may be different, for example, 1.5 μm on one side and 2.0 μm on the other side.

[0106] For example, in some embodiments of the present application, the thickness D2 of the conductive layer of the active material support region provided on both sides of the insulating base may be the same, for example, 0.5 μm for both, or may be different, for example, 0.5 μm on one side and 600 nm on the other side.

[0107] Furthermore, in some embodiments of the present application, the width of the tab connection region is L1, and L1≧10 mm.

[0108] In the above technical solution, by controlling the width of the tab connection area within the above range, not only can the shortest tab requirement for pole sheet welding be met, but also the tab length can be controlled to meet the tab folding space design of the battery and the tab length requirement due to winding.

[0109] More preferably, in some embodiments of the present application, 10 mm≦L1≦40 mm.

[0110] Illustratively, in some embodiments of the present application, L1 is 10 mm, 12 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 38 mm, 40 mm, or a value within a range formed by any two of the above numerical values.

[0111] In some embodiments of the present application, the method for testing the tab area length is a width test on a scale.

[0112] Furthermore, in some embodiments of the present application, referring to FIG. 7, a conductive material (black circles in FIG. 7) is added to the insulating base.

[0113] Furthermore, in some embodiments of the present application, the conductive material comprises at least one of conductive carbon black, carbon nanotubes, acetylene black, or carbon fibers.

[0114] Illustratively, in some embodiments of the present application, the conductive material may include any one selected from conductive carbon black, carbon nanotubes, acetylene black, and carbon fiber. Alternatively, in some embodiments of the present application, the conductive material may include a mixture of conductive carbon black and carbon nanotubes, and these materials may be mixed in any mass ratio. Alternatively, in some embodiments of the present application, the conductive material may be acetylene black, or a mixture of acetylene black and carbon fiber, and these materials may be mixed in any mass ratio. Alternatively, in some embodiments of the present application, the conductive material may be a mixture of conductive carbon black, carbon nanotubes, acetylene black, and carbon fiber, and these materials may be mixed in any mass ratio.

[0115] Furthermore, in some embodiments of the present application, the conductive material is added in an amount of 3% to 10% by mass of the insulating base.

[0116] In the above technical solution, by controlling the proportion of conductive material added to the insulating base within the above range, the requirement for improving the conductivity of welding can be met and the flux effect can be achieved, and the mechanical performance of the insulating base will not be affected by an excessive content.

[0117] More preferably, in some embodiments of the present application, the conductive material is added in an amount of 3.1% to 9.9% by mass of the insulating base.

[0118] For example, in some embodiments of the present application, the conductive material may be added in an amount of 3.2%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 8%, 9%, or 9.5% by mass of the insulating base, or the conductive material may be added in an amount within a range formed by any two of the above numerical values.

[0119] In some embodiments of the present application, the method for testing the components of the insulating-based conductive material is to obtain the content of trace elements by ICP elemental analysis.

[0120] Furthermore, in some embodiments of the present application, the insulating base material comprises at least one of an organic polymer insulating material, an inorganic insulating material, or a composite material.

[0121] Illustratively, in some embodiments of the present application, the insulating base material may include any one selected from an organic polymer insulating material, an inorganic insulating material, or a composite material. Alternatively, in some embodiments of the present application, the insulating base material may include a mixture of an organic polymer insulating material and an inorganic insulating material, and these materials may be mixed in any proportion. Alternatively, in some embodiments of the present application, the insulating base material may include a mixture of an organic polymer insulating material, an inorganic insulating material, and a composite material, and these materials may be mixed in any proportion.

[0122] Furthermore, in some embodiments herein, the organic polymer insulating material comprises at least one of polyamide, polyethylene terephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate, polyparaphenylene terephthalamide, polyphenylene ether, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, or polycarbonate.

[0123] Illustratively, in some embodiments of the present application, the organic polymer insulating material is selected from polyethylene, polypropylene, or polystyrene. Alternatively, in some embodiments of the present application, the organic polymer insulating material includes a mixture of polyoxymethylene and epoxy resin, and these materials may be mixed in any proportion. Alternatively, in some embodiments of the present application, the organic polymer insulating material includes a mixture of polytetrafluoroethylene, polyvinylidene fluoride, and silicone rubber, and these materials may be mixed in any proportion.

[0124] Furthermore, in some embodiments of the present application, the inorganic insulating material comprises at least one of alumina, silicon carbide, or silica.

[0125] For example, in some embodiments of the present application, the inorganic insulating material may include any one selected from alumina, silicon carbide, and silica. Alternatively, in some embodiments of the present application, the inorganic insulating material may include a mixture of alumina and silicon carbide, and these materials may be mixed in any ratio. Alternatively, in some embodiments of the present application, the inorganic insulating material may include a mixture of alumina, silicon carbide, and silica, and these materials may be mixed in any ratio.

[0126] Further, in some embodiments of the present application, the composite material comprises at least one of an epoxy resin fiberglass reinforced composite material or a polyester resin fiberglass reinforced composite material.

[0127] For example, in some embodiments of the present application, the composite material may include any one selected from an epoxy resin glass fiber reinforced composite material and a polyester resin glass fiber reinforced composite material, or may include a mixture of an epoxy resin glass fiber reinforced composite material and a polyester resin glass fiber reinforced composite material, and these materials may be mixed in any ratio.

[0128] Furthermore, in some embodiments of the present application, the material of the conductive layer includes at least one of a metallic conductive material or a carbon-based conductive material.

[0129] Illustratively, in some embodiments of the present application, the material of the conductive layer includes either a metallic conductive material or a carbon-based conductive material, or the material of the conductive layer includes a mixture of a metallic conductive material and a carbon-based conductive material, and these materials may be mixed in any ratio.

[0130] Furthermore, in some embodiments of the present application, the metallic conductive material comprises at least one of aluminum, copper, nickel, titanium, silver, a nickel-copper alloy, or an aluminum-zirconium alloy.

[0131] Illustratively, in some embodiments of the present application, the metallic conductive material includes aluminum, copper, or nickel, or in some embodiments of the present application, the metallic conductive material includes a mixture of aluminum and copper, which may be mixed in any proportion.

[0132] Furthermore, in some embodiments of the present application, the carbon-based conductive material includes at least one of graphite, acetylene black, graphene, or carbon nanotubes.

[0133] Illustratively, in some embodiments of the present application, the carbon-based conductive material includes any one selected from graphite, acetylene black, graphene, and carbon nanotubes, or includes a mixture of graphite and acetylene black, which may be mixed in any proportion, or includes a mixture of graphite, acetylene black, and graphene, which may be mixed in any proportion.

[0134] Furthermore, in some embodiments of the present application, the insulating base is formed by coextrusion drawing under pressure using a die with a specific structure. Illustratively, in some embodiments of the present application, Fig. 8 shows a bullet-shaped die, which can be used to form the insulating base by coextrusion drawing under pressure.

[0135] Further, referring to FIG. 9 , in some embodiments of the present application, a multi-stage roll press processing device is added before the stretched film, and the freshly extruded cast piece is roll-pressed into a thin piece and stretched, thereby forming a special structure in the insulating base, in which the tab connection region is thin and the active material support region is thick.

[0136] Furthermore, in some embodiments of the present application, when a conductive material is added to the insulating base, the conductive material must be added in a corresponding mass % when the base particles of the insulating base material are melted, and then co-extrusion drawing must be performed to form an insulating base with the conductive material added thereto having the above-mentioned special structure.

[0137] Furthermore, in some embodiments of the present application, the conductive layer can be formed on both sides of the insulating base by at least one of water plating, vapor deposition, or electroless plating.

[0138] More preferably, in some embodiments of the present application, the vapor deposition method may be physical vapor deposition. The physical vapor deposition method may be at least one of evaporation and sputtering. The evaporation method may be at least one of vacuum evaporation, thermal evaporation, and electron beam evaporation. The sputtering method may be magnetron sputtering.

[0139] Furthermore, in some embodiments of the present application, the conductive layer in the edge tab connection region can be thickened by increasing the current and plating solution concentration distribution in the edge region using a two-end conduction method using water plating, and thinning the intermediate active material support region with an anode shield, preferably using a copper sulfate solution as the solution and a non-soluble anode plate as the anode to deposit metal.

[0140] More preferably, in some embodiments of the present application, when vapor deposition is performed, the conductive layer in the tab connection region of the edge is thickened, and a method of multiple vapor deposition can be adopted, in which after the vapor deposition of the conductive layer in the middle region is completed, wire feeding and vapor deposition of the tab at the edge is performed alone, and the edge is thickened in a method without wire feeding and vapor deposition in other regions.

[0141] In the following, some specific examples are given to better illustrate the present invention.

[0142] (Insulating base manufacturing)

[0143] The die shown in Figure 8 was used for pressing. After melting the base particles or slices of insulating base material, they were pressed and formed into a thick slab using the die shown in Figure 8. The slab was stretched by setting different draw ratios in the machine direction (MD) and then in the transverse direction (TD). Here, the edge tab area was thinned using the insulating base production edge thinning device shown in Figure 9. After the first stretch, a roll press device was added to further roll-press the thinned slab into a thin film, and then a multi-stage stretching process was performed to finally form a thin film. Here, the conductive material was added in the molten state of the slices or base particles, followed by co-extrusion stretching.

[0144] (Manufacturing composite current collectors)

[0145] The insulating base fabricated as described above was subjected to surface cleaning and then placed in a vacuum deposition chamber. A high-purity metal wire was melted and evaporated in the metal evaporation chamber at high temperatures of 1600°C to 2000°C. The evaporated metal passed through the chamber's cooling system and was finally deposited on both sides of the insulating base to form a conductive layer. The metal wire melting mechanism consisted of multiple independently controlled melting units (including a deposition boat, a wire feed mechanism, and a heating current circuit) arranged along the width of the insulating base. The conductive layer in the edge tab connection region was thickened by performing multiple depositions while only the edge wire feed mechanism was turned on and the middle wire feed mechanism was turned off.

[0146] (Performance test of composite current collector)

[0147] (1) The test method for insulating base thickness / conductive layer thickness is as follows: A cross-sectional sample of the composite current collector is prepared using liquid nitrogen quenching or argon ion etching, and the thickness of the conductive layer and support layer is measured by observing the secondary electron phase morphology of the cross-section of the sample under a scanning electron microscope (1000-5000x magnification). The minimum resolution is on the order of nanometers.

[0148] (2) The strength and ductility of the composite current collector were tested as follows. The sample was cut into a long piece with a top width of 15 mm along the MD direction, and the strength and elongation of the tab connection region were tested. The results are shown in Table 2. In Table 2, the strength of the tab connection region is represented by the average strength value, and the elongation of the tab connection region is represented by the average elongation value. Average intensity = sum of intensity values ​​of 10 samples / 10 Average elongation rate = Sum of elongation rates of 10 samples / 10

[0149] Examples and Comparative Examples

[0150] Composite current collectors were prepared, and the performance parameters of the composite current collectors of the examples and comparative examples are shown in Table 1.

[0151] In Table 1, D1 is the thickness of the insulating base of the active material support region; D2 is the thickness of the conductive layer in the active material support region; D3 is the thickness of the insulating base in the tab connection area; D4 is the thickness of the conductive layer in the tab connection region; The ratio of D4 to D3 is A, The ratio of D1 to D3 is B.

[0152] (Lithium-ion battery manufacturing and detection)

[0153] Using a typical battery coating process, positive or negative electrode slurry was applied to the surface of a current collector, and after drying at 100°C, a positive or negative electrode sheet was obtained. Tab connection areas of different widths for welding metal tabs were secured on both sides of the electrode sheet, and the surface active material layers of the positive and negative electrode sheets were pressed using a typical battery cold pressing process. Here, the pressed density of the positive electrode sheet was 3.4 g / cm. 3 The press density of the negative electrode sheet was 1.6 g / cm 3 It was decided.

[0154] During cold pressing, the number of times the split bands and tabs were torn was collected, and the data was tallied once every 1000 m.

[0155] Then, using a typical battery manufacturing process, the positive electrode sheet, separator, and negative electrode sheet were wound together around a bare cell, and the positive and negative electrode tabs were multi-layer welded using ultrasonic welding, eliminating the transition welding process. The welding power was 4 kW to 6 kW, and the amplitude was 25 to 60 μm. In Example 7 and Comparative Example 1, transition welding was used, where two narrow current collectors were attached to each other along the base of the tab in the welding area, and the welding area was then welded to the fixed-width substrate using roll welding to form the entire tab.

[0156] To evaluate the reliability of the welds of the multi-layer tabs, the pull strength of the ultrasonic welds of the tabs was evaluated.

[0157] (1) The ultrasonic welding tensile strength of the multi-layer tab was measured using a high-speed tensile testing machine.

[0158] The weld tensile strength of the multi-layer tab after welding was measured using a high-speed tensile testing machine. The tab after ultrasonic welding was cut along its base, and the sample was stretched at a speed of 5 mm / min. The maximum force at which the weld broke was read, and this was taken as the weld tensile strength (N).

[0159] (2) 32 samples were selected for testing. The samples were randomly selected for the welded battery. The average ultrasonic welding tensile force of the samples was used to evaluate the mechanical bonding effect of the weld and determine whether there was imperfect welding. The formulas for calculating the average tensile force and standard deviation are as follows: Average welding tensile force = sum of welding tensile force values ​​of 32 samples / 32 The effects of the welding results of the composite current collectors of each example and comparative example are shown in Table 2, and the welding tensile force in Table 2 is the average welding tensile force. Table 2 also shows the number of cold press cleavage times (times / 1000 m).

[0160] To evaluate the reliability of the single layer tab welding employing transition welding in the comparative example, the transition welding tensile strength of the single layer of the tab is evaluated.

[0161] (1) The welding tensile strength of the single-layer transition tab was measured using a high-speed tensile testing machine.

[0162] The weld tensile strength of the single-layer tab after welding was measured using a high-speed tensile testing machine. The tab was cut into a fixed sample 50 mm wide along the diaphragm area. The length should be easy to test. The sample was stretched at a rate of 5 mm / min, and the maximum force value at the time of weld fracture was read and used as the weld tensile strength (N).

[0163] (2) 32 samples were selected for testing. The samples were randomly selected for the welded battery. The average welding tensile force of the samples was used to evaluate the mechanical bonding effect of the weld and determine whether there was imperfect welding. The formulas for calculating the average tensile force and standard deviation are as follows: Average welding tensile force = sum of welding tensile force values ​​of 32 samples / 32

[0164] The welded cell was then placed in a battery case, and electrolyte (EC:EMC volume ratio 3:7, LiPF6 1 mol / L) was poured in, followed by sealing, chemical conversion, and other processes to finally obtain a lithium-ion battery.

[0165] The influence of different conductive layer thicknesses in the tab connection region on the cell DCR was observed by collecting DCR data for 10 cells in a short period of time.

[0166] (1) A DCR test was performed using a cell test device. The specific test method is as follows: By adjusting the cell capacity to 50% SOC, the voltage V1 was recorded, and the cell was discharged for 30 seconds at a discharge current of 4C to obtain a voltage value V2. In this case, DCR = (V1 - V2) / 4C (discharge current). DCR value = sum of DCR values ​​of 10 samples / 10

[0167] (2) Temperature rise test: Before placing the cell in the case, a temperature detection wire was attached to the ultrasonic welding point with Teflon tape, and then the package was filled with electrolyte. The strong charging effect was evaluated by measuring the difference in temperature rise at the ultrasonic welding point using a multipyrometer while discharging at different current rates (3C, 4C, 5C).

[0168] Temperature rise at ultrasonic welding point = Sum of temperature rise at ultrasonic welding points of 10 samples / 10

[0169] The results of lithium battery performance testing are shown in Table 2.

[0170] [Table 1]

[0171] [Table 2]

[0172] From Table 2 above, it can be seen that Comparative Example 1 is a composite current collector with a normal monolithic structure, and the discharge temperature rise at different rates of the ultrasonic welded portions of each of the above Examples of the present application is superior to Comparative Example 1. This shows that the composite current collectors according to the Examples of the present application improve the overcurrent effect of the electrode sheets in the tab connection area.

[0173] Furthermore, by comparing Examples 1 to 6 with Comparative Example 1, it can be seen that the welding tensile strength of Examples 1 to 6 was significantly improved. The reason for this is that the ordinary composite current collector in Comparative Example 1 has a low degree of metallization in the tab connection area, and if direct ultrasonic welding is performed, the problem of incomplete welding is very likely to occur, resulting in a significant decrease in welding tensile strength or even in the inability to weld. Comparative Example 1 cannot employ direct welding, and therefore requires transition welding.

[0174] Furthermore, comparing Examples 2 to 6, when the insulating base thickness D3 of the tab connection region is less than 1.5 μm, the elongation rate of the tab connection region of the composite current collector is low, which may result in problems of cold press cracking and poor welding, and when the insulating base thickness D3 of the tab connection region is greater than 3 μm, the overall strength of the tab connection region is reduced, the elongation rate of the entire tab connection region is reduced, and the frequency of cold press cracking increases. Therefore, when 1.5 μm≦D3≦3 μm, the strength and elongation rate of the tab connection region are excellent, and the welding reliability is high.

[0175] Furthermore, by comparing Examples 8 to 11 with Comparative Example 1, it can be seen that the welding tensile strength of Examples 8 to 11 was significantly increased. The reason for this is that the ordinary composite current collector in Comparative Example 1 has a low degree of metallization in the tab connection area, and when direct ultrasonic welding is performed, the problem of incomplete welding is very likely to occur, resulting in a significant decrease in welding tensile strength or inability to weld.

[0176] Furthermore, by comparing Examples 8 to 11, it was found that when the ratio A of the thickness D4 of the conductive layer in the tab connection region to the thickness D3 of the insulating base in the tab connection region was less than 1, the elongation rate of the tab connection region of the composite current collector was low, which could result in problems of cold press cracking and poor welding. When the ratio A of the thickness D4 of the conductive layer in the tab connection region to the thickness D3 of the insulating base in the tab connection region was greater than 2, the degree of metallization in the tab connection region of the composite current collector was too high, which was likely to cause problems such as a large deposition amount in the tab connection region during the manufacturing process and the generation of voids. Due to the high overall strength, the heating and welding tensile strength at different rates were both improved, but the low elongation rate resulted in a significant increase in the number of cold press cracking times. Therefore, when 1≦A≦2, the strength and elongation rate of the tab connection region were excellent, and the welding reliability was high, which could directly meet the demands for direct ultrasonic welding of the composite current collector and meet the requirements for high-rate discharge safety and reliability of the battery.

[0177] Furthermore, comparing Examples 12 to 17, when the conductive material content in the insulating base was less than 3%, the cell's final temperature rise performance at different rates did not improve, while when the conductive material content in the insulating base was greater than 10%, the conductive material content was too high, resulting in a decrease in the overall elongation of the composite current collector, increased brittleness, an increased probability of cold press cracking, a greater risk of poor welding, increased problems with incomplete welding, and an increase in abnormal cell temperature rise. This indicates that when the conductive material content accounts for 3% to 10% of the insulating base mass, the composite current collector has excellent mechanical properties, and the battery's DCR and temperature rise performance at different rates are improved.

[0178] The performance of Example 7 and Comparative Example 1 are compared and shown in Tables 3 and 4.

[0179] [Table 3]

[0180] [Table 4]

[0181] As can be seen from Table 4 above, in Example 7 and Comparative Example 1, cells were manufactured using the conventional transition welding method of a composite current collector, rather than using direct ultrasonic welding. In Example 7 of this embodiment, the ratio A of the metal thickness D4 of the tab region to the polymer layer thickness D3 of the tab region was less than 1, which may have an impact on manufacturing in terms of cold press cracking. However, after manufacturing a cell using selected regions, the metallization strength of the tab region in Example 7 was high, the polymer layer thickness ratio was small, and the transition weld strength was increased, and overcurrent temperature rise was improved compared to the conventional structure of the Comparative Example.

[0182] It is clear that the above-described embodiments are only some of the embodiments of the present application, but not all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the application for which protection is sought, but only represents selected embodiments of the present application. Based on the embodiments of the present application, any other embodiments that a person skilled in the art can obtain without paying creative labor fall within the scope of protection of the present application.

Claims

1. An insulating base; a conductive layer provided on both sides of the insulating base along a thickness direction of the insulating base; A composite current collector comprising: Along a direction perpendicular to a thickness direction of the composite current collector, the composite current collector includes an active material support region and a tab connection region, a thickness of the insulating base in the tab connection region is smaller than a thickness of the insulating base in the active material support region; A composite current collector, wherein the thickness of the conductive layer in the tab connection region is greater than the thickness of the conductive layer in the active material support region.

2. The thickness of each position of the composite current collector is the same, 2. The composite current collector of claim 1, wherein the thickness of the insulating base in the active material support region is D1, the thickness of the insulating base in the tab connection region is D3, and D3<D1.

3. 3. The composite current collector according to claim 1, wherein the thickness of the conductive layer in the tab connection region is D4, the ratio of D4 to D3 is A, and A≧1.

4. 4. The composite current collector according to claim 1, wherein 1≦A≦2.

5. 5. The composite current collector according to claim 1, wherein the ratio of D1 to D3 is B, and B≧2.

6. 6. The composite current collector according to claim 1, wherein the insulating base of the active material supporting region has a thickness D1, and the thickness D1 satisfies the following condition: 3 μm≦D1≦10 μm.

7. 7. The composite current collector according to claim 1, wherein the thickness of the conductive layer in the active material supporting region is D2, and 0.5 μm≦D2≦1.5 μm.

8. 8. The composite current collector according to claim 1, wherein the insulating base in the tab connection region has a thickness D3, and D3≦3 μm.

9. 9. The composite current collector according to claim 8, wherein 1.5 μm≦D3≦3 μm.

10. 10. The composite current collector of claim 1, wherein the conductive layer in the tab connection region has a thickness D4, and D4≧1.5 μm.

11. 11. The composite current collector according to claim 10, wherein 1.5 μm≦D4≦4 μm.

12. 12. The composite current collector according to claim 1, wherein the width of the tab connection region is L1, and L1≧10 mm.

13. 13. The composite current collector according to claim 12, wherein 10 mm≦L1≦40 mm.

14. 14. The composite current collector according to claim 1, wherein the insulating base is doped with a conductive material.

15. 15. The composite current collector of claim 14, wherein the conductive material comprises at least one of conductive carbon black, carbon nanotubes, acetylene black, or carbon fibers.

16. 16. The composite current collector according to claim 15, wherein the conductive material accounts for 3% to 10% by mass of the insulating base.

17. 17. The composite current collector of claim 1, wherein the insulating base material comprises at least one of an organic polymer insulating material, an inorganic insulating material, or a composite material.

18. 18. The composite current collector according to claim 17, wherein the organic polymer insulating material comprises at least one of polyamide, polyethylene terephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate, polyparaphenylene terephthalamide, polyphenylene ether, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, and polycarbonate; and / or the inorganic insulating material comprises at least one of alumina, silicon carbide, and silica; and / or the composite material comprises at least one of an epoxy resin glass fiber reinforced composite material and a polyester resin glass fiber reinforced composite material.

19. 19. The composite current collector according to claim 1, wherein the material of the conductive layer comprises at least one of a metallic conductive material and a carbon-based conductive material.

20. The metallic conductive material comprises at least one of aluminum, copper, nickel, titanium, silver, a nickel-copper alloy, or an aluminum-zirconium alloy; and / or 20. The composite current collector according to claim 19, wherein the carbon-based conductive material comprises at least one of graphite, acetylene black, graphene, and carbon nanotubes.

21. 21. A polar sheet comprising the composite current collector of any one of claims 1 to 20.

22. A battery comprising the electrode sheet of claim 21.

23. An electrical device comprising the battery of claim 22.

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