Composite current collector and preparation method thereof, electrode plate, battery and power utilization device

Abstract

The invention relates to a composite current collector and a preparation method thereof, an electrode plate, a battery and an electric device. The composite current collector comprises a supporting layer, a bonding layer and a conducting layer, wherein the bonding layer and the conducting layer are sequentially stacked on the two opposite surfaces of the supporting layer in the direction away from the supporting layer; according to the composite current collector, the stripping force between the supporting layer and the conductive layer is effectively improved, and the stripping risk of the composite current collector under long-term soaking in electrolyte is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly to a composite current collector, a preparation method thereof, an electrode sheet, a battery and an electrical device. Background Art

[0002] The statements herein only provide background information related to the present application and do not necessarily constitute prior art.

[0003] Secondary batteries have advantages such as long cycle life, low environmental pollution, high output power and large energy density, and are therefore widely used in electric vehicles and consumer electronic products. The current collector is one of the indispensable components in secondary batteries and plays a role in current conduction and load bearing. Compared with traditional current collectors, a composite current collector with a "metal layer-insulating polymer layer-metal layer" sandwich structure can improve the energy density of secondary batteries, but the peeling force between the metal layer and the insulating polymer layer in this composite current collector is relatively low. Summary of the Invention

[0004] Based on this, the present application provides a composite current collector, a preparation method thereof, an electrode sheet, a battery and an electrical device, aiming to improve the peeling force between the support layer and the conductive layer and reduce the peeling risk of the composite current collector under long-term immersion in the electrolyte.

[0005] In a first aspect of the present application, a composite current collector is provided, which includes a support layer, an adhesive layer and a conductive layer, and the adhesive layer and the conductive layer are sequentially laminated on two opposite surfaces of the support layer along the direction away from the support layer.

[0006] In the above composite current collector, the support layer and the conductive layer are connected through the adhesive layer, which solves the problem of thermal deformation on the surface of the support layer caused by evaporation coating or magnetron sputtering in traditional composite current collectors, effectively improves the peeling force between the support layer and the conductive layer, and reduces the peeling risk of the composite current collector under long-term immersion in the electrolyte.

[0007] In some embodiments, the adhesive layer contains an adhesive, and the adhesive includes one or more of an adhesive composition, polyurethane, epoxy resin, polyacrylate, polyvinyl acetate, unsaturated polyester, phenolic resin, urea-formaldehyde resin, polyolefin resin, silicone resin, ethylene-acrylic copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, acrylic resin, polycarbonate and polyamide, and the adhesive composition includes isocyanate and polyester polyol.

[0008] In some embodiments, the polyurethane includes one or more of thermoplastic polyurethane and reactive polyurethane.

[0009] In some embodiments, the binder includes one or more of the binder composition and the polyurethane.

[0010] In some embodiments, the binder contains isocyanate groups and hydroxyl groups, and the molar ratio of the isocyanate groups to the hydroxyl groups is 0.85 to 1.5, optionally 0.9 to 1.

[0011] In some embodiments, the peel strength between the support layer and the conductive layer is ≥150 N / m, optionally 150 N / m to 600 N / m.

[0012] In some embodiments, based on the mass of the adhesive layer, the mass percentage of the binder is 50% to 100%.

[0013] In some embodiments, the thickness of the adhesive layer is 200 nm to 1500 nm, optionally 300 nm to 700 nm.

[0014] In some embodiments, the adhesive layer further includes a passivating agent.

[0015] In some embodiments, the mass ratio of the binder to the passivating agent is 1 to 2.5, optionally 1.2 to 2.

[0016] In some embodiments, the composite current collector further includes a passivation layer, the passivation layer is disposed between the adhesive layer and the conductive layer, and the passivation layer contains a passivating agent.

[0017] In some embodiments, the ratio of the thickness of the adhesive layer to the thickness of the passivation layer is ≥1, optionally 1 to 500.

[0018] In some embodiments, the thickness of the passivation layer is 1 nm to 500 nm, optionally 10 nm to 200 nm.

[0019] In some embodiments, the passivating agent includes one or more of organic phosphates, chromates, dichromates, Al 2 O 3 , SiO 2 and Si 3 N 4 in one or more.

[0020] In some embodiments, the organic phosphate includes one or more of hydroxyethylidene diphosphonic acid, diethylenetriamine pentamethylene phosphonic acid, triethylenetetramine hexamethylene phosphonic acid, and ethylenediamine tetramethylene phosphonic acid.

[0021] In some embodiments, the chromate includes one or more of sodium chromate, potassium chromate, magnesium chromate, and silver chromate.

[0022] In some embodiments, the dichromate includes one or more of ammonium dichromate, potassium dichromate, sodium dichromate, and magnesium dichromate.

[0023] In some embodiments, the passivator includes one or more of the organic phosphate, the chromate, and the dichromate, and based on the mass of the composite current collector, the mass ratio of phosphorus element and / or chromium element is ≤ 0.3%, and can be optionally 0.001% - 0.1%.

[0024] In some embodiments, the surface of the support layer close to the adhesive layer has a dyne value ≥ 40, and can be optionally 40 - 60.

[0025] In some embodiments, the surface roughness of the support layer close to the adhesive layer is ≥ 0.1 μm, and can be optionally 0.1 μm - 2 μm.

[0026] In some embodiments, the surface roughness of the side of the conductive layer away from the adhesive layer is 0.1 μm - 2 μm.

[0027] In some embodiments, the thickness of the conductive layer is 500 nm - 2500 nm, and can be optionally 800 nm - 2000 nm.

[0028] In some embodiments, the conductive layer contains a conductive material.

[0029] In some embodiments, based on the mass of the conductive layer, the mass ratio of the conductive material is ≥ 99.5%.

[0030] In some embodiments, the conductive material includes one or more of a metal conductive material and a carbon-based conductive material.

[0031] In some embodiments, the metal conductive material includes one or more of aluminum, copper, nickel, titanium, silver, nickel-copper alloy, and aluminum-zirconium alloy.

[0032] In some embodiments, the carbon-based conductive material includes one or more of graphite, acetylene black, graphene, and carbon nanotubes.

[0033] In some embodiments, the thickness of the support layer is 2 μm - 40 μm, and can be optionally 3 μm - 8 μm.

[0034] In some embodiments, the support layer includes one or more of a polymer material and a polymer-based composite material.

[0035] In some embodiments, the polymer material includes one or more of polyamide, polyimide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene, polypropylene, polypropylene styrene, acrylonitrile-butadiene-styrene copolymer, polyvinyl alcohol, polystyrene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, sodium polystyrene sulfonate, polyacetylene, silicone rubber, polyoxymethylene, polyphenylene ether, polyphenylene sulfide, polyethylene glycol, sulfur nitride polymers, polyphenylene, polypyrrole, polyaniline, polythiophene, polypyridine, cellulose, starch, protein, epoxy resin, phenolic resin, their derivatives, their crosslinked products, and their copolymers.

[0036] In some embodiments, the polymer-based composite material includes the polymer material and an additive, and the additive includes one or more of a metal material and an inorganic non-metal material.

[0037] In some embodiments, the metal material includes one or more of aluminum, copper, nickel, iron, silver, titanium, and their alloys.

[0038] In some embodiments, the inorganic non-metal material includes one or more of graphite, conductive carbon, alumina, silica, silicon carbide, and silicon dioxide.

[0039] In a second aspect of the present application, there is provided a method for preparing the composite current collector described in the first aspect of the present application, including the following steps:

[0040] Form the adhesive layer and the conductive layer that are sequentially stacked on two opposite surfaces of the support layer and in a direction away from the support layer.

[0041] The yield rate of the composite current collector prepared by the above preparation method is relatively high, which is beneficial to the mass production of the composite current collector.

[0042] In some embodiments, the step of forming the adhesive layer and the conductive layer that are sequentially stacked includes:

[0043] Dispose a first slurry containing an adhesive on the surface of at least one of the support layer and the conductive layer, and cure the first slurry to form the adhesive layer.

[0044] In some embodiments, the first slurry further includes a passivating agent.

[0045] In some embodiments, the mass ratio of the adhesive to the passivating agent in the first slurry is 1 to 2.5, and may be optionally 1.2 to 2.

[0046] In some embodiments, the method for preparing the composite current collector further includes: a step of forming a passivation layer between the adhesive layer and the conductive layer.

[0047] In some embodiments, the step of forming the passivation layer includes: disposing a second paste containing a passivating agent on one surface of the conductive layer, and curing the second paste to form the passivation layer.

[0048] In some embodiments, the passivating agent includes one or more of organic phosphates, chromates, dichromates, Al 2 O 3 , SiO 2 and Si 3 N 4 .

[0049] In some embodiments, the organic phosphate includes one or more of hydroxyethylidene diphosphonic acid, diethylenetriamine pentamethylenephosphonic acid, triethylenetetramine hexamethylenephosphonic acid, and ethylenediamine tetramethylenephosphonic acid.

[0050] In some embodiments, the chromate includes one or more of sodium chromate, potassium chromate, magnesium chromate, and silver chromate.

[0051] In some embodiments, the dichromate includes one or more of ammonium dichromate, potassium dichromate, sodium dichromate, and magnesium dichromate.

[0052] In a third aspect of the present application, there is provided an electrode tab, including at least one of the composite current collector described in the first aspect of the present application and the composite current collector prepared by the preparation method described in the second aspect of the present application.

[0053] The electrode tab of the present application includes at least one of the composite current collector provided by the present application and the composite current collector prepared by the preparation method provided by the present application, and thus has at least the same advantages as the composite current collector or the composite current collector prepared by the preparation method.

[0054] In a fourth aspect of the present application, there is provided a battery, including the composite current collector described in the first aspect of the present application or the electrode tab described in the third aspect of the present application.

[0055] The battery of the present application includes the composite current collector provided by the present application or the electrode tab provided by the present application, and thus has at least the same advantages as the composite current collector or the electrode tab.

[0056] In a fifth aspect of the present application, there is provided an electrical device, including the battery described in the fourth aspect of the present application.

[0057] The electrical device of the present application includes the battery provided by the present application, and thus has at least the same advantages as the battery.

[0058] Details of one or more embodiments of the present application are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the present application will become apparent from the specification, the drawings, and the claims. Description of the Drawings

[0059] To better describe and illustrate the embodiments or examples provided by the present application, reference may be made to one or more of the accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed application, the currently described embodiments or examples, and the currently understood best mode of these applications. Moreover, in all the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0060] Figure 1 Schematic diagram of a composite current collector according to an embodiment of the present application.

[0061] Figure 2 Schematic diagram of a composite current collector according to another embodiment of the present application.

[0062] Figure 3 Schematic diagram of a battery cell according to an embodiment of the present application.

[0063] Figure 4 is Figure 3 Exploded view of the battery cell shown in an embodiment of the present application.

[0064] Figure 5 Schematic diagram of a battery module according to an embodiment of the present application.

[0065] Figure 6 Schematic diagram of a battery pack according to an embodiment of the present application.

[0066] Figure 7 is Figure 6 Exploded view of the battery pack shown in an embodiment of the present application.

[0067] Figure 8 Schematic diagram of an electrical device powered by a secondary battery according to an embodiment of the present application.

[0068] Description of the Reference Numerals:

[0069] 1 Battery pack; 2 Upper box body; 3 Lower box body; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 Cover plate; 6 Electrical device; 7 Composite current collector; 71 Support layer; 72 Adhesive layer; 73 Conductive layer; 74 Passivation layer. Detailed Embodiments

[0070] Hereinafter, some embodiments of the composite current collector, its preparation method, electrode sheet, battery, and electrical device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually identical structures are omitted. This is to avoid making the following descriptions unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the accompanying drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0071] The "range" disclosed in the present application can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The range defined in this way can include or not include the end values. Any end value can be independently included or not included, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are also listed, the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present application, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" are fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when a certain parameter is expressed as an integer ≥2, it is equivalent to listing the parameter as integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when a certain parameter is expressed as an integer selected from "2 - 10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0072] In the present application, the terms "a plurality of", "a variety of", etc., unless otherwise specified, refer to a quantity greater than 2 or equal to 2. For example, "one or more" means one or greater than or equal to two.

[0073] If there is no special instruction, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0074] As used herein, the mention of "embodiment" means that the specific features, structures or characteristics described in connection with the embodiment may be included in at least one embodiment or implementation of the present application. The appearance of this phrase at various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments. The "implementation" mentioned herein has a similar understanding.

[0075] Those skilled in the art can understand that in the methods of each implementation or embodiment, the written order of each step does not mean a strict execution order that constitutes any limitation to the implementation process. The detailed execution order of each step should be determined according to its function and possible internal logic. If there is no special instruction, all steps of the present application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out sequentially, or may also include steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may also include steps (a), (c) and (b), or may also include steps (c), (a) and (b), etc.

[0076] In the present application, in an open technical feature or technical solution described by words such as "containing", "comprising", "including", etc., without other instructions, additional members other than the listed members are not excluded. It can be regarded as providing both a closed feature or solution composed of the listed members and an open feature or solution that also includes additional members outside the listed members. For example, A includes a1, a2 and a3. Without other instructions, it may also include other members or may not include additional members. It can be regarded as providing both a feature or solution that "A is composed of a1, a2 and a3" and a feature or solution that "A not only includes a1, a2 and a3, but also includes other members". In the present application, without other instructions, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0077] In the present application, "optionally", "optional", "option" mean that it is optional, that is, it refers to any one of two parallel options of "having" or "not having". If "optional" appears in multiple places in a technical solution, without special instructions and without contradictions or mutual restrictions, each "optional" is independent.

[0078] The composite current collector with the traditional "metal-insulating polymer-metal" sandwich structure usually prepares the conductive layer on the surface of the support layer by methods such as evaporation coating or magnetron sputtering. However, the above methods will cause problems such as thermal deformation on the surface of the support layer, resulting in a low peeling force between the support layer and the conductive layer and a high peeling risk under long-term immersion in the electrolyte. Based on this, the present application provides a composite current collector, including a support layer, an adhesive layer, and a conductive layer. The adhesive layer and the conductive layer are sequentially stacked on the two opposite surfaces of the support layer along the direction away from the support layer. In the above composite current collector, the support layer and the conductive layer are connected through the adhesive layer, which solves the problem of thermal deformation on the surface of the support layer in the traditional composite current collector, effectively improves the peeling force between the support layer and the conductive layer, and reduces the peeling risk of the composite current collector under long-term immersion in the electrolyte.

[0079] An embodiment of the present application provides a composite current collector, including a support layer, an adhesive layer, and a conductive layer. The adhesive layer and the conductive layer are sequentially stacked on the two opposite surfaces of the support layer along the direction away from the support layer.

[0080] In the above composite current collector, the support layer and the conductive layer are connected through the adhesive layer, which solves the problem of thermal deformation on the surface of the support layer caused by evaporation coating or magnetron sputtering in the traditional composite current collector, effectively improves the peeling force between the support layer and the conductive layer, and reduces the peeling risk of the composite current collector under long-term immersion in the electrolyte.

[0081] Optionally, the above composite current collector can be a positive current collector or a negative current collector.

[0082] As a non-limiting example, the support layer has two opposite surfaces in its own thickness direction, and the adhesive layer and the conductive layer are sequentially stacked on the two opposite surfaces of the support layer.

[0083] In some embodiments, referring to Figure 1 , the composite current collector 7 includes a support layer 71, an adhesive layer 72, and a conductive layer 73. The adhesive layer 72 and the conductive layer 73 are sequentially stacked on the two opposite surfaces of the support layer 71 along the direction away from the support layer 71.

[0084] In some embodiments, the adhesive layer contains an adhesive, and the adhesive includes one or more of an adhesive composition, polyurethane, epoxy resin, polyacrylate, polyvinyl acetate, unsaturated polyester, phenolic resin, urea-formaldehyde resin, polyolefin resin, silicone resin, ethylene-acrylic copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, acrylic resin, polycarbonate, and polyamide. The adhesive composition includes isocyanate and polyester polyol. Optionally, chemical titration or an infrared spectrometer can be used to test the components of the adhesive in the adhesive layer.

[0085] In some embodiments, the polyurethane includes one or more of thermoplastic polyurethane and reactive polyurethane.

[0086] In some embodiments, the binder includes one or more of a binder composition and polyurethane. Thereby, it is beneficial to further improve the peel strength between the support layer and the conductive layer, and further reduce the peeling risk of the composite current collector under long-term immersion in the electrolyte. The isocyanate in the binder composition contains isocyanate groups, the polyester polyol in the binder composition contains hydroxyl groups, and the polyurethane contains isocyanate groups and hydroxyl groups.

[0087] In some embodiments, the binder contains isocyanate groups and hydroxyl groups, and the molar ratio of the isocyanate groups to the hydroxyl groups is 0.85 to 1.5. When the molar ratio of the isocyanate groups to the hydroxyl groups is within the above range, the content of polar groups in the adhesive layer is relatively high, enhancing the bonding force between the support layer and the conductive layer, thereby further improving the peel strength between the support layer and the conductive layer, and further reducing the peeling risk of the composite current collector under long-term immersion in the electrolyte. It can be understood that the molar ratio of the isocyanate groups to the hydroxyl groups in the isocyanate includes but is not limited to: 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.2, 1.3, 1.4, 1.5. Further, the molar ratio of the isocyanate groups to the hydroxyl groups in the binder is 0.9 to 1.

[0088] In some embodiments, the curing reaction conditions of the binder composition are 25°C to 50°C.

[0089] In some embodiments, the binder composition further includes water.

[0090] In some embodiments, the peel strength between the support layer and the conductive layer is ≥150 N / m. It can be understood that the peel strength between the support layer and the conductive layer includes but is not limited to: 150 N / m, 200 N / m, 250 N / m, 300 N / m, 350 N / m, 400 N / m, 450 N / m, 500 N / m, 550 N / m, 600 N / m. Optionally, the peel strength between the support layer and the conductive layer is 150 N / m to 600 N / m.

[0091] In some embodiments, based on the mass of the adhesive layer, the mass percentage of the binder is 50% to 100%. When the mass percentage of the binder in the adhesive layer is within the above range, it is beneficial to further improve the peel strength between the support layer and the conductive layer, and further reduce the peeling risk of the composite current collector under long-term immersion in the electrolyte.

[0092] In some embodiments, the thickness of the adhesive layer is 200 nm to 1500 nm. Controlling the thickness of the adhesive layer within the above range can improve the welding effect of the tab. It can be understood that the thickness of the adhesive layer includes but is not limited to: 200 nm, 300 nm, 500 nm, 700 nm, 900 nm, 1100 nm, 1300 nm, 1500 nm. Further, the thickness of the adhesive layer is 300 nm to 700 nm.

[0093] In some embodiments, the adhesive layer further contains a passivator. Thus, on the one hand, the adhesive layer containing the passivator can improve the bonding effect between the conductive layer and the support layer, and on the other hand, it can protect the conductive layer and improve the corrosion resistance of the conductive layer under long-term cyclic storage in the electrolyte, thereby further improving the peel strength and its reliability between the support layer and the conductive layer, and further reducing the peeling risk of the composite current collector under long-term immersion in the electrolyte. On the other hand, it can reduce the thickness of the composite current collector, improve its welding reliability, and reduce the energy density of the battery.

[0094] In some embodiments, the mass ratio of the binder to the passivator is 1 to 2.5. When the mass ratio of the binder to the passivator is within the above range, the adhesive layer has excellent bonding and passivation effects, thereby further improving the peel strength and its reliability between the support layer and the conductive layer, further reducing the peeling risk of the composite current collector under long-term immersion in the electrolyte, and improving the welding reliability of the composite current collector. The mass ratio of the binder to the passivator includes but is not limited to: 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.5. Optionally, the mass ratio of the binder to the passivator is 1.2 to 2.

[0095] In some embodiments, the composite current collector further includes a passivation layer, and the passivation layer is disposed between the adhesive layer and the conductive layer, and the passivation layer contains a passivator. The provided passivation layer can protect the conductive layer and improve the corrosion resistance of the conductive layer under long-term cyclic storage in the electrolyte, thereby further improving the peel strength and its reliability between the support layer and the conductive layer, and further reducing the peeling risk of the composite current collector under long-term immersion in the electrolyte.

[0096] In some embodiments, referring to Figure 2 , the composite current collector 7 further includes a passivation layer 74, and the passivation layer 74 is disposed between the adhesive layer 72 and the conductive layer 73, and the passivation layer contains a passivator. The passivation layer 74 disposed between the adhesive layer 72 and the conductive layer 73 can further improve the peel strength and its reliability between the support layer 71 and the conductive layer 73, and further reduce the peeling risk of the composite current collector 7 under long-term immersion in the electrolyte.

[0097] In some embodiments, the ratio of the thickness of the adhesive layer to the thickness of the passivation layer ≥ 1. Controlling the ratio of the thickness of the adhesive layer to the thickness of the passivation layer within the above range can, on the one hand, result in a relatively large peeling force between the support layer and the conductive layer, and on the other hand, lead to a better welding effect of the tab. The ratio of the thickness of the adhesive layer to the thickness of the passivation layer can be selected from 1 to 500.

[0098] In some embodiments, the thickness of the passivation layer is 1 nm to 500 nm. Thereby, the uniformity of the passivation of the composite current collector is improved, which further enhances the corrosion resistance of the conductive layer during long-term cyclic storage of the electrolyte, while taking into account the bonding effect between the conductive layer and the support layer and the welding effect of the composite current collector. The thickness of the passivation layer includes, but is not limited to: 1 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm. Further, the thickness of the passivation layer is 10 nm to 200 nm.

[0099] In some embodiments, the passivating agent includes one or more of organic phosphates, chromates, dichromates, Al 2 O 3 , SiO 2 and Si 3 N 4 . Optionally, the organic phosphate includes one or more of hydroxyethylidene diphosphonic acid, diethylenetriamine pentamethylene phosphonic acid, triethylenetetramine hexamethylene phosphonic acid, and ethylenediamine tetramethylene phosphonic acid. Optionally, the chromate includes one or more of sodium chromate, potassium chromate, magnesium chromate, and silver chromate. Optionally, the dichromate includes one or more of ammonium dichromate, potassium dichromate, sodium dichromate, and magnesium dichromate.

[0100] In some embodiments, the passivating agent includes one or more of organic phosphates, chromates, and dichromates, and based on the mass of the composite current collector, the mass proportion of phosphorus element and / or chromium element ≤ 0.3%. Thereby, the peeling force between the support layer and the conductive layer can be increased. The mass proportion of phosphorus element and / or chromium element includes, but is not limited to: 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%. Optionally, based on the mass of the composite current collector, the mass proportion of phosphorus element and / or chromium element is 0.001% to 0.1%.

[0101] In some embodiments, the dyne value of the surface of the support layer close to the adhesive layer is ≥40. When the dyne value of the surface of the support layer close to the adhesive layer is within the above range, the support layer has appropriate surface energy, thereby further enhancing the peel force between the support layer and the conductive layer and further reducing the peeling risk of the composite current collector under long-term immersion in the electrolyte. Optionally, the dyne value of the surface of the support layer close to the adhesive layer is 40 to 60.

[0102] In some embodiments, the surface roughness of the support layer close to the adhesive layer is ≥0.1 μm. When the surface roughness of the support layer close to the adhesive layer is within the above range, the contact area between the support layer and the binder in the adhesive layer is within an appropriate range, thereby further enhancing the peel force between the support layer and the conductive layer and further reducing the peeling risk of the composite current collector under long-term immersion in the electrolyte. Optionally, the surface roughness of the support layer close to the adhesive layer is 0.1 μm to 2 μm.

[0103] Optionally, in the composite current collector, the dyne value and surface roughness of the surface of the support layer close to the adhesive layer can be tested by the following method: Corrode and remove the conductive layer of the composite current collector, use a degumming cleaning agent to remove the adhesive layer, and then test the dyne value and surface roughness of the support layer surface; for the dyne value, use a dyne pen with a value above 40 to draw a line and observe whether there are breaks. If not, it means the dyne value can reach 40; the surface roughness can be tested by a surface roughness tester, and the wavelength can be selected as 0.8 μm; when the conductive layer includes aluminum, a sodium hydroxide solution with a certain concentration can be used to corrode and remove the conductive layer.

[0104] In some embodiments, the surface roughness of the side of the conductive layer away from the adhesive layer is 0.1 μm to 2 μm. Thereby, the bonding force between the conductive layer and the electrode active material layer can be enhanced while the composite current collector has good conductivity. It can be understood that the surface roughness of the side of the conductive layer away from the adhesive layer includes but is not limited to: 0.1 μm, 0.3 μm, 0.5 μm, 0.8 μm, 1 μm, 1.3 μm, 1.5 μm, 1.8 μm, 2 μm.

[0105] In some embodiments, the thickness of the conductive layer is 500 nm to 2500 nm. Thereby, the internal resistance of the battery can be reduced and the weight energy density of the battery can be increased while the composite current collector has good conductivity. It can be understood that the thickness of the conductive layer includes but is not limited to: 500 nm, 800 nm, 1000 nm, 1200 nm, 1500 nm, 1800 nm, 2000 nm, 2200 nm, 2500 nm. Further, the thickness of the conductive layer is 800 nm to 2000 nm.

[0106] In some embodiments, the conductive layer contains a conductive material.

[0107] In some embodiments, for the mass meter based on the conductive layer, the mass proportion of the conductive material is ≥ 99.5%. Thus, the conductivity of the composite current collector can be improved while meeting the peel force requirements of the electrode tab.

[0108] In some embodiments, the conductive material includes one or more of a metal conductive material and a carbon-based conductive material. Optionally, the metal conductive material includes one or more of aluminum, copper, nickel, titanium, silver, nickel-copper alloy, and aluminum-zirconium alloy. Optionally, the carbon-based conductive material includes one or more of graphite, acetylene black, graphene, and carbon nanotubes.

[0109] In some embodiments, the thickness of the support layer is 2 μm to 40 μm. It can be understood that the thickness of the support layer includes but is not limited to: 2 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm. Optionally, the thickness of the support layer is 3 μm to 8 μm.

[0110] In some embodiments, the support layer includes one or more of a polymer material and a polymer-based composite material.

[0111] In some embodiments, the polymer material includes one or more of polyamide, polyimide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene, polypropylene, polypropylene styrene, acrylonitrile-butadiene-styrene copolymer, polyvinyl alcohol, polystyrene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, sodium polystyrene sulfonate, polyacetylene, silicone rubber, polyoxymethylene, polyphenylene ether, polyphenylene sulfide, polyethylene glycol, polyazotized sulfur-based polymer materials, polyphenylene, polypyrrole, polyaniline, polythiophene, polypyridine, cellulose, starch, protein, epoxy resin, phenolic resin, their derivatives, their crosslinked products, and their copolymers.

[0112] In some embodiments, the polymer-based composite material includes a polymer material and an additive, and the additive includes one or more of a metal material and an inorganic non-metallic material.

[0113] In some embodiments, the metal material includes one or more of aluminum, copper, nickel, iron, silver, titanium, and their alloys;

[0114] In some embodiments, the inorganic non-metallic material includes one or more of graphite, conductive carbon, alumina, silica, silicon carbide, and silica.

[0115] Another embodiment of the present application provides a method for preparing the above composite current collector, including the following steps:

[0116] A bonding layer and a conductive layer are sequentially formed on two opposite surfaces of the support layer and in a direction away from the support layer.

[0117] In the above preparation method, the conductive layer is adhered to the surface of the support layer through the adhesive layer, which solves the problem of thermal deformation on the surface of the support layer in the traditional composite current collector, effectively improves the peel strength between the support layer and the conductive layer, and reduces the peeling risk of the composite current collector under long-term immersion in the electrolyte. In addition, the yield rate of the composite current collector prepared by this preparation method is relatively high, which is beneficial to the mass production of the composite current collector.

[0118] In some embodiments, the step of forming the adhesive layer and the conductive layer stacked in sequence includes:

[0119] A first slurry containing a binder is disposed on the surface of at least one of the support layer and the conductive layer, and the first slurry is cured to form the adhesive layer. As a non-limiting example, the solvent in the first slurry may include water.

[0120] In some embodiments, the first slurry further contains a passivator. Thus, the prepared adhesive layer contains both a binder and a passivator. On the one hand, it can improve the bonding effect between the conductive layer and the support layer. On the other hand, it can protect the conductive layer and improve the corrosion resistance of the conductive layer under long-term cyclic storage in the electrolyte, thereby further enhancing the peel strength between the support layer and the conductive layer and its reliability, and further reducing the peeling risk of the composite current collector under long-term immersion in the electrolyte. On the other hand, it can reduce the thickness of the composite current collector, improve the welding reliability, and reduce the energy density of the battery.

[0121] In some embodiments, the mass ratio of the binder to the passivator in the first slurry is 1 to 2.5. It can be optionally 1.2 to 2. When the mass ratio of the binder to the passivator is within the above range, the prepared adhesive layer has excellent bonding and passivation effects, thereby further enhancing the peel strength between the support layer and the conductive layer and its reliability, and further reducing the peeling risk of the composite current collector under long-term immersion in the electrolyte. Optionally, the mass ratio of the binder to the passivator is 1.2 to 2.

[0122] In some embodiments, the preparation method of the composite current collector further includes: a step of forming a passivation layer between the adhesive layer and the conductive layer. The passivation layer can protect the conductive layer and improve the corrosion resistance of the conductive layer under long-term cyclic storage in the electrolyte, thereby further enhancing the peel strength between the support layer and the conductive layer and its reliability, and further reducing the peeling risk of the composite current collector under long-term immersion in the electrolyte.

[0123] In some embodiments, the step of forming the passivation layer includes: disposing a second paste containing a passivation agent on one surface of the conductive layer, and curing the second paste to form the passivation layer. It can be understood that when preparing the composite current collector including the passivation layer, a first paste containing a binder can be disposed on opposite surfaces of the support layer, and the first paste is cured to form a bonding layer, and then the passivation layer is laminated on the surface of the bonding layer away from the support layer; or a first paste containing a binder is disposed on the surface of the passivation layer away from the conductive layer, and the first paste is cured to form a bonding layer, and then the bonding layer is laminated on opposite surfaces of the support layer.

[0124] In some alternative embodiments, the passivation agent includes one or more of organic phosphates, chromates, dichromates, Al 2 O 3 , SiO 2 and Si 3 N 4 . Optionally, the organic phosphate includes one or more of hydroxyethylidene diphosphonic acid, diethylenetriamine pentamethylene phosphonic acid, triethylenetetramine hexamethylene phosphonic acid, and ethylenediamine tetramethylene phosphonic acid. Optionally, the chromate includes one or more of sodium chromate, potassium chromate, magnesium chromate, and silver chromate. Optionally, the dichromate includes one or more of ammonium dichromate, potassium dichromate, sodium dichromate, and magnesium dichromate.

[0125] Another embodiment of the present application provides an electrode tab, including at least one of the above composite current collector and the composite current collector prepared by the above preparation method. Thus, it is beneficial to improve the energy density and cycling performance of the battery. Optionally, the above electrode tab can be at least one of a positive electrode tab and a negative electrode tab.

[0126] Another embodiment of the present application further provides a battery, including the above composite current collector or electrode tab. Thus, it is beneficial to improve the energy density and cycling performance of the battery. The battery includes a primary battery and a secondary battery; the secondary battery includes but is not limited to: at least one of a lithium-ion secondary battery, a sodium-ion battery, and a magnesium-ion battery; the primary battery includes but is not limited to: a lithium primary battery.

[0127] Another embodiment of the present application further provides an electrical device, including the above battery.

[0128] In addition, the battery and the electrical device of the present application are described below with reference to the accompanying drawings as appropriate.

[0129] Under normal circumstances, a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the charge and discharge process of the battery, active ions are intercalated and deintercalated back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet, mainly to prevent short circuit between the positive and negative electrodes, and at the same time allows ions to pass through.

[0130] Positive electrode sheet

[0131] It can be understood that during the charge and discharge process of the battery, the deintercalation and consumption of lithium (Li) will occur, and the content of Li in the positive electrode sheet is different when the battery is discharged to different states. In the listing of the positive electrode active materials in this application, unless otherwise specified, the content of Li is the initial state of the material. When the positive electrode active material is applied to the positive electrode sheet in the battery system, after charge and discharge cycles, the content of Li in the positive electrode active material contained in the electrode sheet usually changes. Among them, the content of Li can be measured by molar content, but is not limited thereto. Regarding "the content of Li is the initial state of the material", the initial state of the material refers to the state before being fed into the positive electrode slurry. It can be understood that new materials obtained by appropriate modification based on the listed positive electrode active materials are also within the scope of the positive electrode active materials. The aforementioned appropriate modification refers to acceptable modification methods for the positive electrode active materials, and non-limiting examples include coating modification.

[0132] In the listing of the positive electrode active materials in this application, the content of oxygen (O) is only the theoretical state value, and the release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual content of O will fluctuate. Among them, the content of O can be measured by molar content, but is not limited thereto.

[0133] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material.

[0134] As a non-limiting example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode active material layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0135] In some embodiments, the positive electrode current collector can adopt the above-mentioned composite current collector of this application.

[0136] In some embodiments, the positive electrode current collector may be a metal foil or other composite current collector. For example, as the metal foil, aluminum foil may be used. Other composite current collectors may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. Other composite current collectors may be obtained by forming a metal material on a polymer material substrate. In the positive electrode current collector, non-limiting examples of the metal material may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. In the positive electrode current collector, non-limiting examples of the polymer material substrate may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0137] In some embodiments, the positive electrode active material may be a positive electrode active material for a battery known in the art. As non-limiting examples, the positive electrode active material may include one or more of the following materials: lithium phosphate with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as the positive electrode active material of the battery may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of the lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (such as LiCoO 2 ), lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. Non-limiting examples of the lithium phosphate with an olivine structure may include, but are not limited to, lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon. Non-limiting examples of the lithium cobalt oxide may include LiCoO 2 ; non-limiting examples of the lithium nickel oxide may include LiNiO 2 ; non-limiting examples of the lithium manganese oxide may include LiMnO 2 , LiMn 2 O 4 , etc.; non-limiting examples of the lithium nickel cobalt manganese oxide may include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (which may also be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (which may also be abbreviated as NCM 523 ), LiNi 0.5Co 0.25 Mn 0.25 O 2 (which can also be abbreviated as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O 2 (which can also be abbreviated as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O 2 (which can also be abbreviated as NCM 811 ) etc. Non-limiting examples of lithium nickel cobalt aluminum oxide can include LiNi 0.8 Co 0.15 Al 0.05 O 2 .

[0138] The positive electrode active material includes a sodium ion active material.

[0139] As an example, the sodium ion active material can include one or more of the following materials: one or more of sodium transition metal oxides, polyanion-type compounds, and Prussian blue compounds. However, this application is not limited to these materials, and other conventionally known materials that can be used as the positive electrode active material of a sodium ion battery can also be used.

[0140] As an alternative technical solution of this application, in the sodium transition metal oxide, the transition metal can include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. A non-limiting example of the sodium transition metal oxide can be Na x MO 2 , where M can include one or several of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu, and 0 < x ≤ 1.

[0141] As an alternative technical solution of this application, the polyanion-type compound can be a type of compound having sodium ions, transition metal ions, and a tetrahedral (YO 4 ) n- anion unit. The transition metal can include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be one or more of P, S, and Si; n represents the valence state of (YO 4 ) n- .

[0142] The polyanion-type compound can also be a compound having sodium ions, transition metal ions, and a tetrahedral (YO 4 ) n-A class of compounds of anionic units and halogen anions. The transition metal may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y may be one or more of P, S, and Si, and n represents the valence state of (YO 4 ) n- . The halogen may be one or more of F, Cl, and Br.

[0143] The polyanionic compound may also be a class of compounds having sodium ions, tetrahedral (YO 4 ) n- anionic units, polyhedral units (ZO y ) m+ and optionally halogen anions. Y may be one or more of P, S, and Si, and n represents the valence state of (YO 4 ) n- ; Z represents a transition metal, which may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, and m represents the valence state of (ZO y ) m+ ; The halogen may be one or more of F, Cl, and Br.

[0144] The polyanionic compound may include NaFePO 4 , Na 3 V 2 (PO 4 ) 3 (sodium vanadium phosphate, abbreviated as NVP), Na 4 Fe 3 (PO 4 ) 2 (P 2 O 7 ), NaM’PO 4 F and Na 3 (VO y ) 2 (PO 4 ) 2 F 3-2y (0 ≤ y ≤ 1), one or more of them. Among them, M’ in NaM’PO 4 F may include one or more of V, Fe, Mn, and Ni.

[0145] Prussian blue compounds may be a class of compounds having sodium ions, transition metal ions, and cyanide ions (CN - ). The transition metal may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Non-limiting examples of Prussian blue compounds may be Na a Meb Me’ c (CN) 6 , where Me and Me’ can each independently be one or more of Ni, Cu, Fe, Mn, Co, and Zn, 0 < a ≤ 2, 0 < b < 1, 0 < c < 1.

[0146] In some embodiments, the positive electrode active material layer may further optionally include a binder. As a non-limiting example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride - tetrafluoroethylene - propylene terpolymer, vinylidene fluoride - hexafluoropropylene - tetrafluoroethylene terpolymer, tetrafluoroethylene - hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0147] In some embodiments, the positive electrode active material layer may further optionally include a conductive agent. As a non-limiting example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0148] In some embodiments, the positive electrode plate can be prepared by the following method: dispersing the components for preparing the positive electrode plate, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent to form a positive electrode slurry; coating the positive electrode slurry on at least one surface of the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode plate can be obtained. The type of the solvent can be selected from but not limited to any one of the foregoing embodiments, such as N-methylpyrrolidone (NMP). The surface of the positive electrode current collector on which the positive electrode slurry is coated can be a single surface of the positive electrode current collector or two surfaces of the positive electrode current collector. The solid content of the positive electrode slurry can be 40wt% - 80wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000mPa·s - 25000mPa·s. When coating the positive electrode slurry, the coating unit surface density in terms of dry weight (deducting the solvent) can be 15mg / cm 2 -35mg / cm 2 . The tap density of the positive electrode plate can be 3.0g / cm 3 -3.6g / cm 3 , and can be optionally 3.3g / cm 3 -3.5g / cm 3 .

[0149] Negative electrode plate

[0150] The negative electrode plate includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material.

[0151] As a non-limiting example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0152] In some embodiments, the negative electrode current collector may adopt the above-mentioned composite current collector of the present application.

[0153] In some embodiments, the negative electrode current collector may adopt a metal foil or other composite current collector. For example, as the metal foil, a copper foil may be used. Other composite current collectors may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. Other composite current collectors may be obtained by forming a metal material on the polymer material substrate. In the negative electrode current collector, non-limiting examples of the metal material may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. In the negative electrode current collector, non-limiting examples of the polymer material substrate may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0154] In some embodiments, the negative electrode active material may adopt a negative electrode active material for a battery well-known in the art. As a non-limiting example, the negative electrode active material may include one or more of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based materials may include one or more of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based materials may include one or more of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as the negative electrode active material of the battery may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0155] In some embodiments, the negative electrode active material layer may also optionally include a binder. The binder may include one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0156] In some embodiments, the negative electrode active material layer may also optionally include a conductive agent. The conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0157] In some embodiments, the negative electrode active material layer may further optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)), etc.

[0158] In some embodiments, the negative electrode sheet can be prepared in the following manner: dispersing the components for preparing the negative electrode sheet described above, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (non-limiting examples of the solvent include deionized water) to form a negative electrode slurry; coating the negative electrode slurry on at least one surface of the negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode sheet can be obtained. The surface of the negative electrode current collector coated with the negative electrode slurry can be a single surface of the negative electrode current collector or two surfaces of the negative electrode current collector. The solid content of the negative electrode slurry can be 40wt%-60wt%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000mPa·s - 10000mPa·s. When coating the negative electrode slurry, the coating unit surface density in terms of dry weight (deducting the solvent) can be 75g / m 2 -220g / m 2 . The tap density of the negative electrode sheet can be 1.0g / cm 3 -1.8g / cm 3 .

[0159] In some embodiments, the positive electrode current collector and / or the negative electrode current collector adopt the above-mentioned composite current collector of the present application. It can be understood that it can be that only the positive electrode current collector adopts the above-mentioned composite current collector of the present application, or only the negative electrode current collector adopts the above-mentioned composite current collector of the present application. Of course, it can also be that both the positive electrode current collector and the negative electrode current collector adopt the above-mentioned composite current collector of the present application.

[0160] Electrolyte

[0161] The electrolyte has the function of conducting ions between the positive electrode sheet and the negative electrode sheet. The present application does not particularly limit the type of the electrolyte, and it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like or all-solid-state.

[0162] In some embodiments, the electrolyte adopts an electrolytic solution. The electrolytic solution includes an electrolyte salt and a solvent.

[0163] In some embodiments, the electrolyte salt may include lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO 2 F 2) one or more of lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluoro(bis(oxalato))phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0164] In some embodiments, the solvent may include ethylene carbonate (EC, ), propylene carbonate (PC, ), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butenyl carbonate ( ), fluoroethylene carbonate (FEC), methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone, or one or more thereof.

[0165] In some embodiments, the electrolyte may also optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives for improving battery overcharge performance, additives for improving battery high-temperature or low-temperature performance, etc.

[0166] In some embodiments, the additives in the electrolyte may include, but are not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethyl ethylene carbonate (TFPC), etc.

[0167] Separator

[0168] In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of the separator, and any well-known porous structure separator with good chemical stability and mechanical stability can be selected.

[0169] In some embodiments, the material of the separator may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0170] In some embodiments, the thickness of the separator is 6 μm - 40 μm, and may be optionally 12 μm - 20 μm.

[0171] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be made into an electrode assembly by a winding process or a stacking process.

[0172] In some embodiments, the secondary battery may include an outer package. The outer package may be used to encapsulate the above-mentioned electrode assembly and electrolyte.

[0173] In some embodiments, the outer package of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The outer package of the secondary battery may also be a soft package, such as a pouch soft package. The material of the soft package may be plastic. Further, non-limiting examples of the plastic may include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate, etc.

[0174] The secondary battery includes at least one battery cell. The secondary battery may include one or more battery cells.

[0175] In this application, unless otherwise specified, a "battery cell" refers to a basic unit capable of converting chemical energy and electrical energy into each other. Further, generally, it includes at least a positive electrode plate, a negative electrode plate, and an electrolyte. During the charge and discharge process of the battery, active ions are embedded and removed back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in conducting active ions between the positive electrode plate and the negative electrode plate.

[0176] This application has no particular limitation on the shape of the battery cell, and it may be cylindrical, square, or any other arbitrary shape. For example, Figure 3 is a battery cell 5 with a square structure as an example.

[0177] In some embodiments, referring to Figure 4 , the outer package may include a housing 51 and a cover plate 53. Among them, the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. The number of electrode assemblies 52 included in the battery cell 5 may be one or more, and those skilled in the art can select according to actual needs.

[0178] The secondary battery may be a battery module 4 or a battery pack 1.

[0179] The battery module includes at least one battery cell. The number of battery cells included in the battery module may be one or more, and those skilled in the art can select a suitable number according to the application and capacity of the battery module.

[0180] Figure 5 is a battery module 4 as an example. Referring to Figure 5, in the battery module 4, multiple battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other way. Further, the multiple battery cells 5 can be fixed by fasteners.

[0181] Optionally, the battery module 4 can further include a housing having an accommodation space, and the multiple battery cells 5 are accommodated in the accommodation space.

[0182] In some embodiments, the above battery module can also be assembled into a battery pack. The number of battery modules included in the battery pack can be one or more, and those skilled in the art can select a suitable number according to the application and capacity of the battery pack.

[0183] Figure 6 and Figure 7 is the battery pack 1 as an example. Refer to Figure 6 and Figure 7 , in the battery pack 1, a battery box and multiple battery modules 4 arranged in the battery box can be included. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in the battery box in any way.

[0184] In addition, the present application also provides an electric device. The electric device includes the secondary battery provided by the present application. The secondary battery can be used as the power source of the electric device or as the energy storage unit of the electric device. The electric device can include mobile devices, electric vehicles, electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto. Among them, the mobile device can be, for example, a mobile phone, a laptop computer, etc.; the electric vehicle can be, for example, a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc., but is not limited thereto.

[0185] As the electric device, the secondary battery can be selected according to its usage requirements.

[0186] Figure 8 is the electric device 6 as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the high-power and high-energy density requirements of the electric device for the secondary battery, a battery pack or a battery module can be adopted.

[0187] Another example of the device can be a mobile phone, a tablet computer, a laptop computer, etc. This device usually requires being thin and light, and a secondary battery can be used as the power source.

[0188] The embodiments of the present application will be described below. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application. For technologies or conditions not specified in the embodiments, they shall be carried out according to the technologies or conditions described in the literature in the field or according to the product specifications. Reagents or instruments not specified by the manufacturer can all be obtained as conventional products through commercial purchase.

[0189] Example 1

[0190] (1) Preparation of the composite current collector

[0191] The passivator potassium dichromate was uniformly coated on the surface of the thick conductive layer with a thickness of 5 μm by the gravure method to form a passivation layer with a thickness of 100 nm. The conductive layer was an aluminum layer;

[0192] The PET (polyethylene terephthalate) film with a thickness of 6 μm was subjected to corona treatment so that the dyne values of the two surfaces of the PET film in the thickness direction were 42 and the roughness was 0.15 μm, obtaining a support layer;

[0193] Polyurethane glue was coated on the two surfaces of the support layer in the thickness direction, and then placed in an oven at 110 °C for baking to form a bonding layer with a thickness of 500 nm;

[0194] The passivated thick conductive layer was laminated on the two surfaces of the support layer in the thickness direction, and pressed (the pressing temperature was 100 °C). After curing, the curing temperature was 85 ± 5 °C, obtaining a composite current collector of the thick conductive layer.

[0195] Through the sodium hydroxide etching and thinning process, the thickness of the thick conductive layer was etched to 1000 nm, obtaining a composite current collector with a final conductive layer thickness of 1000 nm.

[0196] The roughness of the surface of the conductive layer on the side away from the support layer was controlled to be 1.2 μm through the etching and thinning process.

[0197] (2) Preparation of the secondary battery

[0198] (2.1) Preparation of the positive electrode plate

[0199] The positive electrode active material NCM 811 , conductive carbon black SP and binder PVDF were dispersed in the solvent NMP in a weight ratio of 98:1:1 and mixed evenly to obtain a positive electrode slurry; the positive electrode slurry was uniformly coated on the bilateral surfaces of the composite current collector prepared in the above step (1). After drying and cold pressing, a positive electrode plate was obtained, and the tap density of the positive electrode plate was 3.4 g / cm 3 .

[0200] (2.2) Preparation of the negative electrode plate

[0201] Mix the graphite as the negative electrode active material, sodium carboxymethyl cellulose as the thickener, styrene-butadiene rubber as the binder, and acetylene black as the conductive agent in a mass ratio of 97:1:1:1, add deionized water, and obtain the negative electrode slurry under the action of a vacuum mixer; uniformly coat the negative electrode slurry on both sides of the copper foil; dry the copper foil at room temperature and then transfer it to an oven at 120 °C for drying for 1 h, and then obtain the negative electrode sheet through cold pressing and slitting. The compaction density of the negative electrode sheet is 1.6 g / cm 3 。

[0202] (2.3)Separator

[0203] Select a separator with PP laminated on both sides of PE (PP / PE / PP).

[0204] (2.4)Preparation of electrolyte

[0205] The organic solvent is a mixed solution containing ethylene carbonate (EC) and ethyl methyl carbonate (EMC). Among them, the volume ratio of EC to EMC is 30:70. In a glove box with an argon atmosphere with a water content of <10 ppm, dissolve the fully dried lithium salt LiPF 6 in the organic solvent and mix evenly to obtain the electrolyte. Among them, the concentration of the lithium salt is 1 mol / L.

[0206] (2.5)Preparation of battery

[0207] Stack the positive electrode sheet, separator, and negative electrode sheet in sequence, with the separator between the positive and negative electrode sheets to play a role in isolation. After winding into a bare battery core, use the double-sided metal edge wrapping method to roll weld and transfer the welding tabs, install them into an aluminum-plastic film, then bake at 80 °C to remove water, inject the non-aqueous electrolyte, seal, and after processes such as standing, hot and cold pressing, formation, clamping, and grading, obtain the finished battery.

[0208] Example 2-24

[0209] Basically the same as Example 1, the difference is that: in step (1), the preparation method of the composite current collector is different. Specifically, the composition and thickness of the adhesive layer and the composition and thickness of the passivation layer are changed. See Table 1 for details.

[0210] Example 25

[0211] Basically the same as Example 1, the difference is that: in step (1), the preparation method of the composite current collector is different.

[0212] The preparation method of the composite current collector in this example is as follows:

[0213] Prepare a slurry by mixing potassium dichromate as the passivating agent and polyurethane glue in a mass ratio of 1:1. Coat the slurry on the surface of the thick conductive layer with a thickness of 5 μm, and then put it into an oven at 110 °C for baking to form an adhesive layer with a thickness of 700 nm;

[0214] The PET film with a thickness of 6 μm is subjected to corona treatment so that the dyne value of the two surfaces of the PET film in the thickness direction is 42 and the roughness is 0.15 μm, and a support layer is obtained;

[0215] Passivate the thick conductive layer on the two surfaces in the thickness direction of the support layer, press (the pressing temperature is 100 °C), and after curing, the curing temperature is 85 ± 5 °C, to obtain a composite current collector with a thick conductive layer.

[0216] Through the sodium hydroxide etching and thinning process, the thickness of the thick conductive layer is etched to 1000 nm to obtain a composite current collector with a final conductive layer thickness of 1000 nm.

[0217] Control the roughness of the surface of the conductive layer far from the support layer to 1.2 μm through the etching and thinning process.

[0218] Examples 26 - 43

[0219] Basically the same as Example 1, the difference is that: in step (1), the preparation method of the composite current collector is different, specifically, the composition and thickness of the adhesive layer are changed, as shown in Table 1 for details.

[0220] Comparative Example 1

[0221] Basically the same as Example 1, the difference is that: in step (1), the preparation method of the composite current collector is different;

[0222] The preparation method of the composite current collector in this comparative example is as follows:

[0223] The PET film with a thickness of 6 μm is subjected to corona treatment so that the dyne value of the two surfaces of the PET film in the thickness direction is 42 and the roughness is 0.15 μm, and a support layer is obtained;

[0224] Use the evaporation method to prepare a conductive layer on the two surfaces in the thickness direction of the support layer. The unilateral thickness of the conductive layer is 1000 nm, and then by controlling the number of evaporation passes and the wire feeding speed during evaporation, the deposition grain size is changed to make the roughness of the surface of the conductive layer far from the support layer 1.2 μm.

[0225] The binders and passivators used in the composite current collectors prepared in Examples 1 - 43 can all be obtained commercially.

[0226] The product parameters of the composite current collectors prepared in Examples 1 - 43 and Comparative Example 1 are shown in Tables 1 - 2.

[0227] Product parameter testing and performance testing

[0228] (1) Test method for the molar ratio of isocyanate groups and hydroxyl groups

[0229] (1.1) Test method for isocyanate groups

[0230] The content of isocyanate groups in the binder was tested by potentiometric titration. The specific steps were as follows: Weigh 0.2 g to 0.3 g of the sample into a 250 mL beaker, add 10 mL of chloroform to dissolve the sample, and then accurately add 20.00 mL of 0.2 mol / L hexahydropyridine chlorobenzene solution with a pipette. After the reaction was complete for 30 min, add 150 mL of absolute ethanol, then perform magnetic stirring, insert the reference electrode and the composite electrode. Under continuous stirring, perform potentiometric titration with 0.1 mol / L hydrochloric acid standard solution, record the corresponding volume and pH while titrating. When approaching the end point, record the corresponding pH value after adding a continuous increment (0.1 mL) of the titrant each time. Stop when the pH change becomes slow; at the same time, perform a blank experiment.

[0231] W 1 (%) = (V 0 - V 1 ) * C * 4.202 / m Formula I

[0232] In Formula I, W 1 is the mass percentage content of isocyanate groups in the binder, V 1 is the volume of HCl standard consumed in the blank experiment (mL), V 0 is the volume of HCl standard consumed in the experiment (mL), C is the actual concentration of the hydrochloric acid standard solution (mol / L), and m is the mass of the sample.

[0233] (1.2) Test method for hydroxyl groups

[0234] Using toluenesulfonic acid as a catalyst, in ethyl acetate, the acetylation reaction of acetic anhydride with hydroxyl groups was carried out. The excess acetic anhydride was hydrolyzed with a mixed solution of pyridine and water, and the generated acetic acid was then titrated with a sodium hydroxide standard titration solution to calculate the content of hydroxyl groups in the binder.

[0235] The specific steps were as follows: Take a sample (the sampling amount is about 145 / estimated hydroxyl value. If the estimated hydroxyl value is 70 mg KOH / g, then it is 145 / 70 = 2 g) into a 250 ml iodine flask, add 10 mL of acetylating agent, cover the flask stopper, heat in a water bath at (50 ± 2) °C, shake to make the sample dissolve evenly, and then heat at 50 °C for 20 min (shake it every few minutes). Take out the iodine flask and cool it. Rinse the bottle mouth, bottle stopper, and bottle wall with 10 mL to 20 mL of hydrolysis solution with a volume ratio of pyridine: water of 3:1. Let it stand for 5 min to hydrolyze the excess acetic anhydride. Add 3 to 5 drops of 1% phenolphthalein indicator, and titrate with 0.5 moL / L sodium hydroxide standard titration solution until a pink color appears and does not fade for 15 s, which is the end point. Perform a blank test in the same way at the same time.

[0236] Qv = 56.1 * (V 3 - V 2 ) c / m 0 + Av Equation II

[0237] In Equation II, Qv is the hydroxyl value of the sample (mg KOH / g); V 2 is the volume of the standard sodium hydroxide solution consumed in titrating the blank (mL); V 3 is the volume of the standard sodium hydroxide solution consumed in titrating the test sample (mL); c is the concentration of the standard sodium hydroxide titration solution (mol / L); m 0 is the mass of the test sample (g); 56.1 is the molar mass of potassium hydroxide (g / mol); Av is the acid value of the sample (mgKOH / g).

[0238] Based on the W 1 and Qv tested according to steps (1.1) and (1.2), calculate the molar ratio of isocyanate groups and hydroxyl groups in the binder.

[0239] (2) Test method for the thickness of each layer

[0240] Prepare a cross-sectional sample of the composite current collector using the liquid nitrogen quenching method or the argon ion etching method. Observe the secondary electron phase morphology of the sample cross-section using a scanning electron microscope magnified (1000 - 30000 times). The minimum resolution can reach the nanometer level, and measure the thickness of the support layer, adhesive layer, passivation layer, or conductive layer.

[0241] (3) Test method for phosphorus element, chromium element, and materials in the conductive layer

[0242] Perform the test using ICP (inductively coupled plasma) elemental analysis method.

[0243] (4) Test method for the peel strength between the support layer and the conductive layer

[0244] After the composite current collector is non-corona surface bonded to the EAA (ethylene acrylic acid copolymer) film, then cover a 12 μm PET on the EAA film and bond it on a heat sealer. The temperature of the heat sealer is 120 °C, and the pressure of the heat sealer is 0.2 MPa. Cut the bonded sample into a sample with a length of 100 mm and a width of 20 mm. Use 3M double-sided tape to stick the non-bonded surface of the conductive layer on the steel plate; clamp the sample on the fixture of a tensile machine and perform a 180 °C peel test under the conditions of a spacing of 50 mm and a speed of 300 mm / min. Read the peel strength value and convert it into the unit of N / m. There are 5 parallel samples, and finally take the average value of the peel strengths of the 5 parallel samples.

[0245] (5) Test method for the peel strength between the support layer and the conductive layer after the composite current collector is immersed in the electrolyte

[0246] Cut the composite current collector into samples with a size of 30 mm × 10 mm, place them in an aluminum-plastic film, add 20 g of electrolyte, seal it, and then soak it at a high temperature of 60 °C. After 72 h, take out the samples for peel strength testing. After the samples are attached to the non-corona surface of the EAA film, cover the EAA film with a 12-μm PET and attach them on a heat sealer. The temperature of the heat sealer is 120 °C, and the pressure of the heat sealer is 0.2 MPa. Cut the attached samples into samples with a length of 100 mm and a width of 20 mm, and use 3M double-sided tape to attach the non-attached surface of the conductive layer to the steel plate; clamp the samples on the fixture of a tensile machine, and conduct a 180 °C peel test under the conditions of a spacing of 50 mm and a speed of 300 mm / min, read the peel strength value, convert it into the unit of N / m, with 3 groups of parallel samples, and finally take the average value of the peel strength of the 3 groups of parallel samples.

[0247] The peel strength test results between the support layer and the conductive layer of the composite current collectors prepared in Examples 1-43 and Comparative Example 1 are shown in Table 3.

[0248] Table 1

[0249]

[0250] In Table 1, " / " indicates the absence of the substance or parameter.

[0251] Table 2

[0252]

[0253]

[0254] Table 3

[0255]

[0256]

[0257] As can be seen from Tables 1-3, there is no adhesive layer between the support layer and the conductive layer in the composite current collector of Comparative Example 1. Compared with the composite current collector of Comparative Example 1, the peel strength between the support layer and the conductive layer of the composite current collectors of Examples 1-43 is relatively high, and after the composite current collector is soaked in the electrolyte, the peel strength between the support layer and the conductive layer is also relatively high, indicating that the support layer and the conductive layer of the composite current collectors of Examples 1-43 of the present application are connected through an adhesive layer, effectively improving the peel strength between the support layer and the conductive layer and reducing the peeling risk of the composite current collector under long-term immersion in the electrolyte.

[0258] The descriptions of the above embodiments tend to emphasize the differences between the embodiments. The same or similar parts can be referred to each other. For the sake of brevity, they are not elaborated herein.

[0259] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples, and embodiments having the same constitution in essence as the technical idea and achieving the same effect within the scope of the technical solution of this application are all included in the technical scope of this application. In addition, within the scope of not departing from the gist of this application, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways constructed by combining some constituent elements in the embodiments are also included in the scope of this application.

Claims

1. A composite current collector, characterized in that, it includes a support layer, an adhesive layer and a conductive layer, and the adhesive layer and the conductive layer are sequentially laminated on two opposite surfaces of the support layer in a direction away from the support layer.

2. The composite current collector according to claim 1, characterized in that, the adhesive layer contains an adhesive, and the adhesive includes one or more of an adhesive composition, polyurethane, epoxy resin, polyacrylate, polyvinyl acetate, unsaturated polyester, phenolic resin, urea-formaldehyde resin, polyolefin resin, silicone resin, ethylene-acrylic copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, acrylic resin, polycarbonate and polyamide, and the adhesive composition includes isocyanate and polyester polyol; Optionally, the polyurethane includes one or more of thermoplastic polyurethane and reactive polyurethane.

3. The composite current collector according to claim 2, characterized in that, the adhesive includes one or more of the adhesive composition and the polyurethane; Optionally, the adhesive contains isocyanate groups and hydroxyl groups, and the molar ratio of the isocyanate groups to the hydroxyl groups is 0.85 to 1.5, further optionally 0.9 to 1.

4. The composite current collector according to claim 1, characterized in that, the peel strength between the support layer and the conductive layer is ≥150 N / m, optionally 150 N / m to 600 N / m.

5. The composite current collector according to any one of claims 1 to 4, characterized in that, based on the mass of the adhesive layer, the mass proportion of the adhesive is 50% to 100%.

6. The composite current collector according to any one of claims 1 to 4, characterized in that, the thickness of the adhesive layer is 200 nm to 1500 nm, optionally 300 nm to 700 nm.

7. The composite current collector according to any one of claims 1 to 4, characterized in that, the adhesive layer further contains a passivating agent; Optionally, the mass ratio of the adhesive to the passivating agent is 1 to 2.5, further optionally 1.2 to 2.

8. The composite current collector according to any one of claims 1 to 4, characterized in that, the composite current collector further includes a passivation layer, the passivation layer is provided between the adhesive layer and the conductive layer, and the passivation layer contains a passivating agent.

9. The composite current collector according to claim 8, characterized in that, the passivation layer has one or more of the following characteristics: (1) The ratio of the thickness of the adhesive layer to the thickness of the passivation layer is ≥1, optionally 1 to 500; (2) The thickness of the passivation layer is 1 nm to 500 nm, optionally 10 nm to 200 nm.

10. The composite current collector according to any one of claims 7 to 9, characterized in that, The passivator includes one or more of organic phosphates, chromates, dichromates, Al 2 O 3 , SiO 2 , and Si 3 N 4 ; Optionally, the organic phosphate includes one or more of hydroxyethane diphosphonic acid, diethylenetriamine pentamethylene phosphonic acid, triethylenetetramine hexamethylene phosphonic acid and ethylenediamine tetramethylene phosphonic acid; Optionally, the chromate includes one or more of sodium chromate, potassium chromate, magnesium chromate and silver chromate; Optionally, the dichromate includes one or more of ammonium dichromate, potassium dichromate, sodium dichromate, and magnesium dichromate.

11. The composite current collector according to claim 10, wherein, the passivator includes one or more of the organic phosphate, the chromate, and the dichromate, and based on the mass of the composite current collector, the mass ratio of phosphorus element and / or chromium element is ≤ 0.3%, and can be optionally 0.001% - 0.1%.

12. The composite current collector according to any one of claims 1 to 11, wherein, the support layer has one or more of the following characteristics: (1) The dyne value of the surface of the support layer close to the adhesive layer is ≥ 40, and can be optionally 40 - 60; (2) The surface roughness of the support layer close to the adhesive layer is ≥ 0.1μm, and can be optionally 0.1μm - 2μm.

13. The composite current collector according to any one of claims 1 to 11, wherein, the surface roughness of the side of the conductive layer away from the adhesive layer is 0.1μm - 2μm.

14. The composite current collector according to any one of claims 1 to 11, wherein, the thickness of the conductive layer is 500nm - 2500nm, and can be optionally 800nm - 2000nm.

15. The composite current collector according to any one of claims 1 to 11, wherein, the conductive layer contains a conductive material; Optionally, based on the mass of the conductive layer, the mass ratio of the conductive material is ≥ 99.5%; Optionally, the conductive material includes one or more of a metal conductive material and a carbon-based conductive material; Further optionally, the metal conductive material includes one or more of aluminum, copper, nickel, titanium, silver, nickel-copper alloy, and aluminum-zirconium alloy; Further optionally, the carbon-based conductive material includes one or more of graphite, acetylene black, graphene, and carbon nanotubes.

16. The composite current collector according to any one of claims 1 to 11, wherein, the thickness of the support layer is 2μm - 40μm, and can be optionally 3μm - 8μm.

17. The composite current collector according to any one of claims 1 to 11, wherein, the support layer includes one or more of a polymer material and a polymer-based composite material; Optionally, the polymer material includes one or more of polyamide, polyimide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene, polypropylene, polypropylene styrene, acrylonitrile-butadiene-styrene copolymer, polyvinyl alcohol, polystyrene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, sodium polystyrene sulfonate, polyacetylene, silicone rubber, polyoxymethylene, polyphenylene ether, polyphenylene sulfide, polyethylene glycol, polyazotized sulfur-based polymer materials, polyphenylene, polypyrrole, polyaniline, polythiophene, polypyridine, cellulose, starch, protein, epoxy resin, phenolic resin, their derivatives, their crosslinked products, and their copolymers. Optionally, the polymer-based composite material includes the polymer material and additives, and the additives include one or more of metal materials and inorganic non-metallic materials; Further optionally, the metal materials include one or more of aluminum, copper, nickel, iron, silver, titanium, and their alloys; Further optionally, the inorganic non-metallic materials include one or more of graphite, conductive carbon, alumina, silica, silicon carbide, and silicon dioxide.

18. The method for preparing a composite current collector according to any one of claims 1 to 17, characterized in that, comprises the following steps: Form the adhesive layer and the conductive layer which are sequentially stacked on two opposite surfaces of the support layer and in a direction away from the support layer.

19. According to the preparation method of claim 18, characterized in that, The step of forming the adhesive layer and the conductive layer which are sequentially stacked includes: Dispose a first slurry containing an adhesive on the surface of at least one of the support layer and the conductive layer, and cure the first slurry to form the adhesive layer.

20. According to the preparation method of claim 19, characterized in that, The first slurry further contains a passivating agent; Optionally, the mass ratio of the adhesive to the passivating agent in the first slurry is 1 to 2.5, and further optionally 1.2 to 2.

21. According to the preparation method of claim 18, characterized in that, further includes: The step of forming a passivation layer between the adhesive layer and the conductive layer; Optionally, the step of forming the passivation layer includes: Dispose a second slurry containing a passivating agent on one surface of the conductive layer, and cure the second slurry to form the passivation layer.

22. According to the preparation method of claim 20 or 21, characterized in that, The passivator includes one or more of organic phosphates, chromates, dichromates, Al 2 O 3 , SiO 2 and Si 3 N 4 ; Optionally, the organic phosphates include one or more of hydroxyethylidene diphosphonic acid, diethylenetriamine pentamethylene phosphonic acid, triethylenetetramine hexamethylene phosphonic acid, and ethylenediamine tetramethylene phosphonic acid; Optionally, the chromates include one or more of sodium chromate, potassium chromate, magnesium chromate, and silver chromate; Optionally, the dichromates include one or more of ammonium dichromate, potassium dichromate, sodium dichromate, and magnesium dichromate.

23. An electrode pole piece, characterized in that, includes at least one of the composite current collectors according to any one of claims 1 to 17 and the composite current collectors prepared by the preparation method according to any one of claims 18 to 22.

24. A battery, characterized in that, includes the composite current collector according to any one of claims 1 to 17 or the electrode pole piece according to claim 23.

25. An electrical device, characterized in that, includes the battery according to claim 24.

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