Composite current collector and preparation method therefor, electrode sheet, battery, and electric device

Abstract

A composite current collector and a preparation method therefor, an electrode sheet, a battery, and an electric device. The composite current collector comprises a supporting layer, bonding layers, and conductive layers, and a bonding layer and a conductive layer are sequentially stacked on each of the two opposite surfaces of the supporting layer in a direction moving away from the supporting layer. The composite current collector effectively enhances the peel strength between the supporting layer and the conductive layer, and reduces the peeling risk of the composite current collector under long-term immersion in an electrolyte.

Description

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

[0001] Cross-references

[0002] This application refers to Chinese patent application No. 202311587450.0 filed on November 24, 2023, entitled "Composite current collector and its preparation method, electrode plate, battery and electrical device", which is incorporated into this application in its entirety by reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a composite current collector and a preparation method thereof, an electrode plate, a battery, and an electrical device. Background Art

[0004] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0005] Secondary batteries have advantages such as long cycle life, low environmental pollution, high output power, and high energy density, and are therefore widely used in electric vehicles and consumer electronics. The current collector is one of the indispensable components of secondary batteries, playing the role of current conduction and load support in secondary batteries. Compared with traditional current collectors, composite current collectors with a "metal layer-insulating polymer layer-metal layer" sandwich structure can improve the energy density of secondary batteries. However, the peeling force between the metal layer and the insulating polymer layer in this composite current collector is relatively low.

[0006] Summary of the Invention

[0007] Based on this, the present application provides a composite current collector and its preparation method, electrode plate, battery and electrical device, aiming to enhance 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 electrolyte.

[0008] In a first aspect of the present application, a composite current collector is provided, comprising a support layer, an adhesive layer and a conductive layer, wherein the adhesive layer and the conductive layer are sequentially stacked on two opposite surfaces of the support layer and in a direction away from the support layer.

[0009] In the above-mentioned composite current collector, the support layer and the conductive layer are connected by an adhesive layer, which solves the problem of thermal deformation of the support layer surface caused by evaporation 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.

[0010] In some embodiments, the bonding layer comprises a bonding agent, and the bonding agent includes one or more of a bonding composition, polyurethane, epoxy resin, polyacrylate, polyvinyl acetate, unsaturated polyester, phenolic resin, urea-formaldehyde resin, polyolefin resin, silicone resin, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, acrylic resin, polycarbonate and polyamide, and the bonding composition includes isocyanate and polyester polyol.

[0011] In some embodiments, the polyurethane includes one or more of thermoplastic polyurethane and reactive polyurethane.

[0012] In some embodiments, the adhesive comprises one or more of the adhesive composition and the polyurethane.

[0013] In some embodiments, the binder contains isocyanate groups and hydroxyl groups, and the molar ratio of the isocyanate groups to the hydroxyl groups is 0.85-1.5, and can be optionally 0.9-1.

[0014] In some embodiments, the peeling force between the support layer and the conductive layer is ≥150 N / m, and can be optionally 150 N / m to 600 N / m.

[0015] In some embodiments, based on the mass of the adhesive layer, the mass of the adhesive accounts for 50% to 100%.

[0016] In some embodiments, the thickness of the adhesive layer is 200 nm to 1500 nm, and can be optionally 300 nm to 700 nm.

[0017] In some embodiments, the bonding layer further comprises a passivating agent.

[0018] In some embodiments, the mass ratio of the binder to the passivator is 1 to 2.5, and can be optionally 1.2 to 2.

[0019] In some embodiments, the composite current collector further includes a passivation layer, the passivation layer is disposed between the bonding layer and the conductive layer, and the passivation layer contains a passivating agent.

[0020] In some embodiments, the ratio of the thickness of the bonding layer to the thickness of the passivation layer is ≥1, and can be selected from 1 to 500.

[0021] In some embodiments, the thickness of the passivation layer is 1 nm to 500 nm, and can be optionally 10 nm to 200 nm.

[0022] In some embodiments, the passivating agent includes one or more of an organic phosphate, a chromate, a dichromate, Al2O3, SiO2, and Si3N4.

[0023] In some embodiments, the organic phosphate includes one or more of hydroxyethylidene diphosphonic acid, diethylene triamine penta methylene phosphonic acid, triethylene tetraamine hexa methylene phosphonic acid, and ethylene diamine tetra methylene phosphonic acid.

[0024] In some embodiments, the chromate includes one or more of sodium chromate, potassium chromate, magnesium chromate, and silver chromate.

[0025] In some embodiments, the dichromate includes one or more of ammonium dichromate, potassium dichromate, sodium dichromate, and magnesium dichromate.

[0026] 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 proportion of phosphorus element and / or chromium element is ≤0.3%, and can be optionally 0.001% to 0.1%.

[0027] In some embodiments, the dyne value of the surface of the support layer close to the bonding layer is ≥40, and can be optionally 40-60.

[0028] In some embodiments, the roughness of the surface of the support layer close to the bonding layer is ≥0.1 μm, and can be optionally 0.1 μm to 2 μm.

[0029] In some embodiments, the roughness of the surface of the conductive layer away from the bonding layer is 0.1 μm to 2 μm.

[0030] In some embodiments, the thickness of the conductive layer is 500 nm to 2500 nm, and can be optionally 800 nm to 2000 nm.

[0031] In some embodiments, the conductive layer comprises a conductive material.

[0032] In some embodiments, based on the mass of the conductive layer, the mass proportion of the conductive material is ≥99.5%.

[0033] In some embodiments, the conductive material includes one or more of a metallic conductive material and a carbon-based conductive material.

[0034] In some embodiments, the metallic conductive material includes one or more of aluminum, copper, nickel, titanium, silver, nickel-copper alloy, and aluminum-zirconium alloy.

[0035] In some embodiments, the carbon-based conductive material includes one or more of graphite, acetylene black, graphene, and carbon nanotubes.

[0036] In some embodiments, the thickness of the support layer is 2 μm to 40 μm, and optionally 3 μm to 8 μm.

[0037] In some embodiments, the support layer includes one or more of a polymer material and a polymer-based composite material.

[0038] In some embodiments, the polymer material includes one or more of polyamide, polyimide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene, polypropylene, polypropylene, acrylonitrile-butadiene-styrene copolymer, polyvinyl alcohol, polystyrene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, sodium polystyrene sulfonate, polyacetylene, silicone rubber, polyformaldehyde, polyphenylene ether, polyphenylene sulfide, polyethylene glycol, polysulfur nitride polymer materials, polyphenylene, polypyrrole, polyaniline, polythiophene, polypyridine, cellulose, starch, protein, epoxy resin, phenolic resin, their derivatives, their cross-linked products and their copolymers.

[0039] 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-metallic material.

[0040] In some embodiments, the metal material includes one or more of aluminum, copper, nickel, iron, silver, titanium, and alloys thereof.

[0041] In some embodiments, the inorganic non-metallic material includes one or more of graphite, conductive carbon, aluminum oxide, silicon oxide, silicon carbide, and silicon dioxide.

[0042] In a second aspect of the present application, a method for preparing the composite current collector according to the first aspect of the present application is provided, comprising the following steps:

[0043] The adhesive layer and the conductive layer are sequentially stacked on two opposite surfaces of the support layer and in a direction away from the support layer.

[0044] The composite current collector prepared by the above preparation method has a relatively high yield rate, which is conducive to the mass production of the composite current collector.

[0045] In some embodiments, the step of forming the adhesive layer and the conductive layer stacked in sequence includes:

[0046] A first slurry containing a binder is provided on a surface of at least one of the support layer and the conductive layer, and the first slurry is cured to form the bonding layer.

[0047] In some embodiments, the first slurry further comprises a passivating agent.

[0048] In some embodiments, the mass ratio of the binder to the passivator in the first slurry is 1 to 2.5, and can be optionally 1.2 to 2.

[0049] In some embodiments, the method for preparing the composite current collector further includes: forming a passivation layer between the bonding layer and the conductive layer.

[0050] In some embodiments, the step of forming the passivation layer includes: disposing a second slurry containing a passivating agent on one surface of the conductive layer, and curing the second slurry to form the passivation layer.

[0051] In some embodiments, the passivating agent includes one or more of an organic phosphate, a chromate, a dichromate, Al2O3, SiO2, and Si3N4.

[0052] In some embodiments, the organic phosphate includes one or more of hydroxyethylidene diphosphonic acid, diethylene triamine penta methylene phosphonic acid, triethylene tetraamine hexa methylene phosphonic acid, and ethylene diamine tetra methylene phosphonic acid.

[0053] In some embodiments, the chromate includes one or more of sodium chromate, potassium chromate, magnesium chromate, and silver chromate.

[0054] In some embodiments, the dichromate includes one or more of ammonium dichromate, potassium dichromate, sodium dichromate, and magnesium dichromate.

[0055] The third aspect of the present application provides an electrode plate, comprising 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.

[0056] The electrode plate of the present application includes at least one of the composite current collector provided in the present application and the composite current collector prepared by the preparation method provided in 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.

[0057] In a fourth aspect of the present application, a battery is provided, comprising the composite current collector described in the first aspect of the present application or the electrode plate described in the third aspect of the present application.

[0058] The battery of the present application includes the composite current collector provided by the present application or the electrode pole piece provided by the present application, and thus has at least the same advantages as the composite current collector or the electrode pole piece.

[0059] In a fifth aspect of the present application, an electrical device is provided, comprising the battery described in the fourth aspect of the present application.

[0060] The electric device of the present application includes the battery provided by the present application, and thus has at least the same advantages as the battery.

[0061] The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more of the accompanying drawings. The additional details or examples used to describe the accompanying drawings should not be considered as limiting the scope of the disclosed application, the embodiments or examples currently described, and any of the best modes currently understood for these applications. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the accompanying drawings:

[0063] FIG1 is a schematic diagram of a composite current collector according to one embodiment of the present application.

[0064] FIG2 is a schematic diagram of a composite current collector according to another embodiment of the present application.

[0065] FIG3 is a schematic diagram of a battery cell according to an embodiment of the present application.

[0066] FIG. 4 is an exploded view of the battery cell shown in FIG. 3 according to an embodiment of the present application.

[0067] FIG5 is a schematic diagram of a battery module according to an embodiment of the present application.

[0068] FIG6 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0069] FIG. 7 is an exploded view of the battery pack shown in FIG. 6 according to an embodiment of the present application.

[0070] FIG8 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.

[0071] Description of reference numerals:

[0072] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery cell; 51 shell; 52 electrode assembly; 53 cover plate; 6 power device; 7 composite current collector; 71 support layer; 72 adhesive layer; 73 conductive layer; 74 passivation layer. DETAILED DESCRIPTION

[0073] Below, some embodiments of the composite current collector and its preparation method, electrode plate, battery and electrical device of the present application are described in detail with appropriate reference to the 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 the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0074] " scope " disclosed in the present application can be limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and any end value can be included or not included independently, and can be arbitrarily combined, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 listed, and if the maximum range value 3,4 and 5 are also listed, then the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is merely an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to listing the parameter as, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and so on. For example, when a parameter is expressed as an integer selected from "2-10", this is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0075] In this application, "a plurality of" or "a plurality of" refers to a number greater than or equal to 2 unless otherwise specified. For example, "one or more" means one or more than or equal to two.

[0076] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0077] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment or implementation of the present application. The appearance of such phrases in various locations in the specification does not necessarily refer to the same embodiment, nor does it necessarily refer to independent or alternative embodiments that are mutually exclusive with other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments. References to "implementations" herein have a similar understanding.

[0078] It will be appreciated by those skilled in the art that, in the methods of various embodiments or examples, the order in which the steps are written does not imply a strict order of execution and does not constitute any limitation on the implementation process, and the detailed order of execution of each step should be determined by its function and possible inherent logic. Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0079] In this application, in the open technical features or technical solutions described with words such as "contain", "include", and "include", unless otherwise specified, additional members other than the listed members are not excluded, and it can be regarded as providing both closed features or solutions consisting of the listed members and open features or solutions that also include additional members in addition to the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or may not include additional members. It can be regarded as providing both the feature or solution of "A consists of a1, a2, and a3" and the feature or solution of "A includes not only a1, a2, and a3, but also other members". In this application, unless otherwise specified, 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.

[0080] In this application, the terms "optionally," "optional," and "optional" are optional and refer to either option being present or absent. If a technical solution contains multiple "options," each option is considered independent unless otherwise specified and there are no conflicts or constraints.

[0081] The composite current collector of the traditional "metal-insulating polymer-metal" sandwich structure usually adopts the method of evaporation or magnetron sputtering to prepare the conductive layer on the surface of the support layer. However, the above methods will cause problems such as thermal deformation of the surface of the support layer, resulting in a low peeling force between the support layer and the conductive layer, and a high risk of peeling 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, wherein the adhesive layer and the conductive layer are stacked in sequence on two opposite surfaces of the support layer and in a direction away from the support layer; the support layer and the conductive layer in the above composite current collector are connected by the adhesive layer, which solves the problem of thermal deformation of the support layer surface in the traditional composite current collector, effectively improves the peeling force between the support layer and the conductive layer, and reduces the risk of peeling of the composite current collector under long-term immersion in the electrolyte.

[0082] One embodiment of the present application provides a composite current collector, comprising a support layer, an adhesive layer, and a conductive layer. The adhesive layer and the conductive layer are sequentially stacked on two opposite surfaces of the support layer and in a direction away from the support layer.

[0083] In the above-mentioned composite current collector, the support layer and the conductive layer are connected by an adhesive layer, which solves the problem of thermal deformation of the support layer surface caused by evaporation 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.

[0084] In some embodiments, the composite current collector may be a positive electrode current collector, or may be a negative electrode current collector.

[0085] As a non-limiting example, the support layer has two surfaces opposite to each other in its thickness direction, and the adhesive layer and the conductive layer are sequentially stacked on the two opposite surfaces of the support layer.

[0086] In some embodiments, referring to FIG. 1 , the composite current collector 7 includes a support layer 71 , an adhesive layer 72 , and a conductive layer 73 , which are sequentially stacked on opposite surfaces of the support layer 71 and away from the support layer 71 .

[0087] In some embodiments, the bonding layer comprises a bonding agent, the bonding agent comprising one or more of a bonding composition, polyurethane, epoxy resin, polyacrylate, polyvinyl acetate, unsaturated polyester, phenolic resin, urea-formaldehyde resin, polyolefin resin, silicone resin, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, acrylic resin, polycarbonate and polyamide, and the bonding composition comprises isocyanate and polyester polyol.

[0088] In some embodiments, the composition of the adhesive in the adhesive layer can be tested using chemical titration or infrared spectroscopy.

[0089] In some embodiments, the polyurethane comprises one or more of a thermoplastic polyurethane and a reactive polyurethane.

[0090] In some embodiments, the binder comprises one or more of a bonding composition and a polyurethane. This further enhances the peeling force between the support layer and the conductive layer and reduces the risk of peeling of the composite current collector during long-term immersion in the electrolyte. The isocyanate in the bonding composition contains an isocyanate group, the polyester polyol in the bonding composition contains a hydroxyl group, and the polyurethane contains both an isocyanate group and a hydroxyl group.

[0091] In some embodiments, the binder contains isocyanate groups and hydroxyl groups, and the molar ratio of isocyanate groups to hydroxyl groups is 0.85 to 1.5. The molar ratio of isocyanate groups to hydroxyl groups is within the above range, so that the content of polar groups in the adhesive layer is relatively high, which enhances the bonding force between the support layer and the conductive layer, thereby further improving the peeling force between the support layer and the conductive layer, and further reducing the risk of peeling of the composite current collector under long-term immersion in the electrolyte. It can be understood that the molar ratio of isocyanate groups to hydroxyl groups in 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. Furthermore, the molar ratio of isocyanate groups to hydroxyl groups in the binder is 0.9 to 1.

[0092] In some embodiments, the curing reaction condition of the bonding composition is 25°C to 50°C.

[0093] In this application, °C means degrees Celsius.

[0094] In some embodiments, the bonding composition further includes water.

[0095] In some embodiments, the peel force between the support layer and the conductive layer is ≥150 N / m (Newtons / meter). It is understood that the peel force 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, and 600 N / m.

[0096] In some embodiments, the peeling force between the support layer and the conductive layer is 150 N / m to 600 N / m.

[0097] In some embodiments, the binder comprises 50% to 100% by weight of the adhesive layer. A binder content within this range further enhances the peeling force between the support layer and the conductive layer, and further reduces the risk of peeling of the composite current collector during long-term immersion in the electrolyte.

[0098] 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 is 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, and 1500 nm. Furthermore, the thickness of the adhesive layer is 300 nm to 700 nm.

[0099] In this application, nm means nanometer.

[0100] In some embodiments, the adhesive layer further comprises a passivating agent. Thus, the adhesive layer comprising the passivating agent can, on the one hand, improve the bonding effect between the conductive layer and the support layer, and on the other hand, protect the conductive layer and improve the corrosion resistance of the conductive layer during long-term circulation storage in the electrolyte, thereby further improving the peeling force and reliability between the support layer and the conductive layer, and further reducing the risk of peeling of the composite current collector during long-term immersion in the electrolyte. Furthermore, the thickness of the composite current collector can be reduced, improving its welding reliability, and reducing the energy density of the battery.

[0101] In some embodiments, the mass ratio of the binder to the passivator is 1 to 2.5. The mass ratio of the binder to the passivator is within the above range, so that the bonding layer has both excellent bonding and passivation effects, thereby further improving the peeling force and reliability between the support layer and the conductive layer, further reducing the risk of peeling 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, and 2.5.

[0102] In some embodiments, the mass ratio of the binder to the passivator is 1.2-2.

[0103] In some embodiments, the composite current collector further includes a passivation layer disposed between the adhesive layer and the conductive layer, the passivation layer comprising a passivating agent. The passivation layer protects the conductive layer and improves the corrosion resistance of the conductive layer during long-term electrolyte storage and circulation, thereby further improving the peeling force and reliability between the support layer and the conductive layer, and further reducing the risk of peeling of the composite current collector during long-term electrolyte immersion.

[0104] In some embodiments, referring to FIG2 , the composite current collector 7 further includes a passivation layer 74 disposed between the bonding layer 72 and the conductive layer 73. The passivation layer 74 includes a passivating agent. The passivation layer 74 disposed between the bonding layer 72 and the conductive layer 73 can further enhance the peeling force and reliability between the support layer 71 and the conductive layer 73, and further reduce the risk of peeling of the composite current collector 7 during long-term immersion in the electrolyte.

[0105] In some embodiments, the ratio of the thickness of the bonding layer to the thickness of the passivation layer is ≥ 1. Controlling the ratio of the thickness of the bonding layer to the thickness of the passivation layer within the above range can, on the one hand, increase the peeling force between the support layer and the conductive layer, and on the other hand, improve the welding effect of the tab.

[0106] In some embodiments, the ratio of the thickness of the adhesive layer to the thickness of the passivation layer is 1-500.

[0107] In some embodiments, the thickness of the passivation layer is 1 nm to 500 nm. This improves the uniformity of the passivation of the composite current collector, thereby further improving the corrosion resistance of the conductive layer under long-term circulation 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, and 500 nm. Furthermore, the thickness of the passivation layer is 10 nm to 200 nm.

[0108] In some embodiments, the passivating agent includes one or more of an organophosphate, a chromate, a dichromate, Al2O3, SiO2, and Si3N4.

[0109] In some embodiments, the organophosphate includes one or more of hydroxyethylidene diphosphonic acid, diethylene triamine penta methylene phosphonic acid, triethylene tetraamine hexa methylene phosphonic acid, and ethylene diamine tetra methylene phosphonic acid.

[0110] In some embodiments, the chromate includes one or more of sodium chromate, potassium chromate, magnesium chromate, and silver chromate.

[0111] In some embodiments, the dichromate includes one or more of ammonium dichromate, potassium dichromate, sodium dichromate, and magnesium dichromate.

[0112] In some embodiments, the passivating agent includes one or more of an organic phosphate, a chromate, and a dichromate, and the weight percentage of phosphorus and / or chromium, based on the weight of the composite current collector, is ≤ 0.3%. This can improve the peeling force between the support layer and the conductive layer. The weight percentages of phosphorus and / or chromium include, but are not limited to, 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, and 0.3%.

[0113] In some embodiments, 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%.

[0114] In some embodiments, the dyne value of the surface of the support layer near the bonding layer is ≥ 40. The dyne value of the surface of the support layer near the bonding layer is within the above range, so that the support layer has a suitable surface energy, thereby further improving the peeling force between the support layer and the conductive layer, and further reducing the risk of peeling of the composite current collector under long-term immersion in the electrolyte.

[0115] In some embodiments, the dyne value of the support layer near the bonding layer is 40-60.

[0116] In some embodiments, the surface roughness of the support layer near the bonding layer is ≥ 0.1 μm (micrometer). The surface roughness of the support layer near the bonding layer is within the above range, so that the contact area between the support layer and the binder in the bonding layer is within a suitable range, thereby further improving the peeling force between the support layer and the conductive layer and further reducing the risk of peeling of the composite current collector under long-term immersion in the electrolyte.

[0117] In some embodiments, the roughness of the surface of the support layer close to the bonding layer is 0.1 μm to 2 μm.

[0118] In some embodiments, in the composite current collector, the dyne value and roughness of the surface of the support layer close to the bonding layer can be tested by the following method: corroding and removing the conductive layer of the composite current collector, removing the bonding layer with a debonding agent, and then testing the dyne value and roughness of the surface of the support layer; the dyne value is measured by drawing a line with a dyne pen above 40 to observe whether there are breakpoints. If not, it means that the dyne value can reach 40; the roughness can be tested by a roughness tester, and the wavelength can be selected as 0.8 μm; when the conductive layer includes aluminum, a certain concentration of sodium hydroxide solution can be used to corrode and remove the conductive layer.

[0119] In some embodiments, the surface roughness of the conductive layer on the side away from the bonding layer is 0.1 μm to 2 μm. This can improve the bonding strength between the conductive layer and the electrode active material layer while maintaining good conductivity of the composite current collector. It is understood that the surface roughness of the conductive layer on the side away from the bonding 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, and 2 μm.

[0120] In some embodiments, the thickness of the conductive layer is 500 nm to 2500 nm. This can reduce the internal resistance of the battery and increase the battery's gravimetric energy density while maintaining good conductivity of the composite current collector. It is 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, and 2500 nm. Furthermore, the thickness of the conductive layer is 800 nm to 2000 nm.

[0121] In some embodiments, the conductive layer comprises a conductive material.

[0122] In some embodiments, the conductive material accounts for ≥99.5% of the conductive layer's mass, thereby improving the conductivity of the composite current collector while meeting the peeling force requirements of the electrode sheet.

[0123] In some embodiments, the conductive material includes one or more of a metallic conductive material and a carbon-based conductive material.

[0124] In some embodiments, the metallic conductive material includes one or more of aluminum, copper, nickel, titanium, silver, nickel-copper alloy, and aluminum-zirconium alloy.

[0125] In some embodiments, the carbon-based conductive material includes one or more of graphite, acetylene black, graphene, and carbon nanotubes.

[0126] In some embodiments, the thickness of the support layer is 2 μm to 40 μm. It is 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, and 40 μm.

[0127] In some embodiments, the thickness of the support layer is 3 μm to 8 μm.

[0128] In some embodiments, the support layer comprises one or more of a polymer material and a polymer-based composite material.

[0129] In some embodiments, the polymer material includes one or more of polyamide, polyimide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene, polypropylene, polypropylene, acrylonitrile-butadiene-styrene copolymer, polyvinyl alcohol, polystyrene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, sodium polystyrene sulfonate, polyacetylene, silicone rubber, polyformaldehyde, polyphenylene ether, polyphenylene sulfide, polyethylene glycol, polysulfur nitride polymer materials, polyphenylene, polypyrrole, polyaniline, polythiophene, polypyridine, cellulose, starch, protein, epoxy resin, phenolic resin, their derivatives, their cross-linked products and their copolymers.

[0130] 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.

[0131] In some embodiments, the metal material includes one or more of aluminum, copper, nickel, iron, silver, titanium, and alloys thereof;

[0132] In some embodiments, the inorganic non-metallic material includes one or more of graphite, conductive carbon, aluminum oxide, silicon oxide, silicon carbide, and silicon dioxide.

[0133] Another embodiment of the present application provides a method for preparing the composite current collector, comprising the following steps:

[0134] An adhesive layer and a conductive layer are sequentially stacked on two opposite surfaces of the support layer and in a direction away from the support layer.

[0135] In the above preparation method, the conductive layer is bonded to the surface of the support layer through the adhesive layer, which solves the problem of thermal deformation of the support layer surface in the traditional composite current collector, effectively improves the peeling force between the support layer and the conductive layer, and reduces the risk of peeling of the composite current collector under long-term immersion in the electrolyte; in addition, the composite current collector prepared by this preparation method has a relatively high yield, which is conducive to mass production of composite current collectors.

[0136] In some embodiments, the step of forming the adhesive layer and the conductive layer stacked in sequence includes:

[0137] A first slurry containing a binder is provided on a surface of at least one of the support layer and the conductive layer, and the first slurry is cured to form a bonding layer. As a non-limiting example, the solvent in the first slurry may include water.

[0138] In some embodiments, the first slurry further comprises a passivator. Thus, the resulting adhesive layer comprises both a binder and a passivator, which, on the one hand, 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 circulation and storage of the electrolyte, thereby further improving the peeling force and reliability between the support layer and the conductive layer, and further reducing the risk of peeling of the composite current collector under long-term immersion in the electrolyte. Furthermore, it can reduce the thickness of the composite current collector, improve welding reliability, and reduce the energy density of the battery.

[0139] In some embodiments, the mass ratio of the binder to the passivator in the first slurry is 1 to 2.5. When the mass ratio of the binder to the passivator is within the above range, the prepared bonding layer has both excellent bonding and passivation effects, thereby further improving the peeling force and reliability between the support layer and the conductive layer, and further reducing the risk of peeling of the composite current collector under long-term immersion in the electrolyte.

[0140] In some embodiments, the mass ratio of the binder to the passivator is 1.2-2.

[0141] In some embodiments, the method for preparing the composite current collector further includes 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 during long-term electrolyte circulation and storage, thereby further improving the peeling force and reliability between the support layer and the conductive layer, and further reducing the risk of peeling of the composite current collector during long-term immersion in the electrolyte.

[0142] In some embodiments, the step of forming the passivation layer includes: disposing a second slurry containing a passivator on one surface of the conductive layer, and curing the second slurry to form the passivation layer. It is understood that when preparing a composite current collector including a passivation layer, a first slurry containing a binder can be disposed on two opposing surfaces of a support layer, the first slurry can be cured to form a bonding layer, and the passivation layer can be laminated on the surface of the bonding layer away from the support layer; or a first slurry containing a binder can be disposed on the surface of the passivation layer away from the conductive layer, the first slurry can be cured to form a bonding layer, and the bonding layer can be laminated on two opposing surfaces of the support layer.

[0143] In some optional embodiments, the passivating agent includes one or more of an organic phosphate, a chromate, a dichromate, Al2O3, SiO2, and Si3N4.

[0144] In some embodiments, the organophosphate includes one or more of hydroxyethylidene diphosphonic acid, diethylene triamine penta methylene phosphonic acid, triethylene tetraamine hexa methylene phosphonic acid, and ethylene diamine tetra methylene phosphonic acid.

[0145] In some embodiments, the chromate includes one or more of sodium chromate, potassium chromate, magnesium chromate, and silver chromate.

[0146] In some embodiments, the dichromate includes one or more of ammonium dichromate, potassium dichromate, sodium dichromate, and magnesium dichromate.

[0147] Another embodiment of the present application provides an electrode plate comprising at least one of the composite current collector and the composite current collector prepared by the above preparation method, thereby facilitating improvement of the energy density and cycle performance of the battery.

[0148] In some embodiments, the electrode plate may be at least one of a positive electrode plate and a negative electrode plate.

[0149] Yet another embodiment of the present application provides a battery comprising the composite current collector or electrode sheet described above. This advantageously improves the battery's energy density and cycle performance. The battery comprises 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; and the primary battery includes, but is not limited to, a lithium primary battery.

[0150] Yet another embodiment of the present application provides an electrical device comprising the above-mentioned battery.

[0151] In addition, the battery and the electric device of the present application will be described below with reference to the drawings as appropriate.

[0152] Typically, a secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are inserted and removed between the positive and negative electrodes. The electrolyte conducts ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0153] Positive electrode

[0154] It is understandable that the battery will be accompanied by lithium (Li) deintercalation and consumption during the charge and discharge process, and the content of Li in the positive electrode plate is different when the battery is discharged to different states. In the list of positive electrode active materials in this application, unless otherwise specified, the content of Li is the initial state of the material. The positive electrode active material is applied to the positive electrode plate in the battery system, and after the charge and discharge cycle, the content of Li in the positive electrode active material contained in the plate will usually change. Among them, the content of Li can be measured by molar content, but is not limited to this. Regarding "the content of Li is the initial state of the material", the initial state of the material refers to the state before the material is added to the positive electrode slurry. It is understandable that new materials obtained by appropriate modification on the basis of the listed positive electrode active materials are also within the scope of positive electrode active materials. The aforementioned appropriate modification refers to acceptable modification methods for positive electrode active materials, and non-limiting examples include coating modification.

[0155] In the examples of positive electrode active materials in this application, the oxygen (O) content is only a theoretical value. Lattice oxygen release will cause the molar content of oxygen to change, and the actual O content will fluctuate. The O content can be measured by molar content, but is not limited to this.

[0156] 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, wherein the positive electrode active material layer includes a positive electrode active material.

[0157] As a non-limiting example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0158] In some embodiments, the positive electrode current collector may be the composite current collector described above in this application.

[0159] In some embodiments, the positive electrode current collector may be a metal foil or other composite current collector. For example, aluminum foil may be used as the metal foil. 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 base layer. Other composite current collectors can 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), polyethylene (PE), etc.

[0160] In some embodiments, the positive electrode active material may be a positive electrode active material for a battery that is well known in the art. As a non-limiting example, the positive electrode active material may include one or more of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide (such as LiCoO2), 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 olivine-structured lithium-containing phosphates may include, but are not limited to, one or more of 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 iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Non-limiting examples of lithium cobalt oxides may include LiCoO2; non-limiting examples of lithium nickel oxides may include LiNiO2; non-limiting examples of lithium manganese oxides may include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxides may include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ) etc. Non-limiting examples of lithium nickel cobalt aluminum oxide may include LiNi 0.8 Co 0.15 Al 0.05 O2.

[0161] The positive electrode active material includes a sodium ion active material.

[0162] As an example, the sodium ion active material may include one or more of the following materials: sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds. However, the present application is not limited to these materials, and other conventionally known materials that can be used as sodium ion battery positive electrode active materials may also be used.

[0163] As an optional technical solution of the present application, in the sodium transition metal oxide, 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 sodium transition metal oxides may be Na x MO2, wherein M may include one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, and 0<x≤1.

[0164] As an optional technical solution of the present application, the polyanionic compound can be a compound having sodium ions, transition metal ions and tetrahedral (YO4) n- A class of compounds with anionic units. Transition metals 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; n represents (YO4) n- valence.

[0165] Polyanionic compounds can also be sodium ions, transition metal ions, tetrahedral (YO4) n- A class of compounds containing anion units and halogen anions. Transition metals 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 (YO4) n- valence state; the halogen can be one or more of F, Cl and Br.

[0166] Polyanionic compounds can also be sodium ions, tetrahedral (YO4) n- Anion unit, polyhedron unit (ZOy ) m+ and an optional halogen anion. Y can be one or more of P, S and Si, and n represents (YO4) n- valence state; 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 (ZO y ) m+ valence state; the halogen can be one or more of F, Cl and Br.

[0167] Polyanionic compounds may include NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated as NVP), Na4Fe3(PO4)2(P2O7), NaM'PO4F and Na3(VO y )2(PO4)2F 3-2y (0≤y≤1) wherein M′ in NaM′PO4F may include one or more of V, Fe, Mn and Ni.

[0168] Prussian blue compounds can be 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 include Na a Me b Me' c (CN)6, wherein 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.

[0169] In some embodiments, the positive electrode active material layer may further optionally include a binder. As non-limiting examples, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0170] In some embodiments, the positive electrode active material layer may further include a conductive agent. As non-limiting examples, 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.

[0171] In some embodiments, a positive electrode sheet can be prepared by dispersing the components for preparing the positive electrode sheet, such as the positive electrode active material, conductive agent, binder, and any other components, in a solvent to form a positive electrode slurry; coating the positive electrode slurry on at least one side of a positive electrode current collector, and performing drying, cold pressing, and other processes to obtain a positive electrode sheet. The type of solvent can be selected from, but not limited to, any of the aforementioned embodiments, such as N-methylpyrrolidone (NMP). The surface of the positive electrode current collector coated with the positive electrode slurry can be a single surface of the positive electrode current collector or both surfaces of the positive electrode current collector. The surface of the positive electrode current collector coated with the positive electrode slurry can be a single surface of the positive electrode current collector or both surfaces of the positive electrode current collector. The solid content of the positive electrode slurry can be 40 wt% to 80 wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000 mPa·s to 25000 mPa·s. When applying the positive electrode slurry, the coating unit area density based on dry weight (excluding solvent) can be 15 mg / cm 2 -35mg / cm 2 The compaction density of the positive electrode can be 3.0g / cm 3 -3.6g / cm 3 , optional 3.3g / cm 3 -3.5g / cm 3 .

[0172] Negative electrode

[0173] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material.

[0174] As a non-limiting example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer is disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0175] In some embodiments, the negative electrode current collector may be the composite current collector described above.

[0176] In some embodiments, the negative electrode current collector may be a metal foil or other composite current collector. For example, copper foil may be used as the metal foil. 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 can be obtained by forming a metal material on a 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), polyethylene (PE), etc.

[0177] In some embodiments, the negative electrode active material may adopt negative electrode active materials for batteries that are well known in the art. As non-limiting examples, 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, lithium titanate, etc. Silicon-based materials may include one or more of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. 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 traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0178] In some embodiments, the negative electrode active material layer may further 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).

[0179] In some embodiments, the negative electrode active material layer may further include a conductive agent, which may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0180] In some embodiments, the negative electrode active material layer may further optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0181] In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (a non-limiting example of the solvent is deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on at least one side of the negative electrode current collector, and after drying, cold pressing and other processes, 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 on a dry weight basis (excluding the solvent) can be 75g / m 2 -220g / m 2 The compaction density of the negative electrode can be 1.0g / cm 3 -1.8g / cm 3 .

[0182] In this application, mPa·s means millipascal·second, g / m 2 Indicates grams per square meter, g / cm 3 Indicates grams per cubic centimeter.

[0183] In some embodiments, the positive electrode current collector and / or the negative electrode current collector adopts the composite current collector described above in this application. It is understood that only the positive electrode current collector can adopt the composite current collector described above in this application, or only the negative electrode current collector can adopt the composite current collector described above in this application. Of course, both the positive electrode current collector and the negative electrode current collector can also adopt the composite current collector described above in this application.

[0184] electrolytes

[0185] The electrolyte conducts ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0186] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0187] In some embodiments, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO2F2), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorodioxalatophosphate (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP).

[0188] 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), butylene carbonate One or more of 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.

[0189] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0190] 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), trifluoromethylethylene carbonate (TFPC), and the like.

[0191] Isolation film

[0192] In some embodiments, the secondary battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0193] In some embodiments, the material of the separator can include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can 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 can be the same or different, without particular limitation.

[0194] In some embodiments, the isolation film has a thickness of 6 μm-40 μm, and optionally 12 μm-20 μm.

[0195] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0196] In some embodiments, the secondary battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0197] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the secondary battery can also be a soft shell, such as a pouch-type soft shell. The material of the soft shell can be plastic. Further, non-limiting examples of plastic can include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0198] A secondary battery includes at least one battery cell. A secondary battery may include one or more battery cells.

[0199] In this application, unless otherwise specified, a "battery cell" refers to a basic unit that can achieve the mutual conversion of chemical energy and electrical energy. Further, generally speaking, it includes at least a positive electrode plate, a negative electrode plate, and an electrolyte. During the battery's charge and discharge process, active ions are embedded in and out of the positive and negative electrode plates. The electrolyte plays the role of conducting active ions between the positive and negative electrode plates.

[0200] The present application has no particular limitation on the shape of the battery cell, which can be cylindrical, square, or any other shape. For example, FIG3 shows a battery cell 5 with a square structure as an example.

[0201] In some embodiments, referring to Figure 4, the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can be formed into an electrode assembly 52 through a winding process or a lamination 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 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to actual needs.

[0202] The secondary battery may be a battery module 4 or a battery pack 1 .

[0203] A battery module includes at least one battery cell. The number of battery cells contained in a battery module can be one or more, and those skilled in the art can select an appropriate number based on the application and capacity of the battery module.

[0204] FIG5 shows an example battery module 4. Referring to FIG5 , in the battery module 4, multiple battery cells 5 may be arranged sequentially along the length of the battery module 4. Of course, they may also be arranged in any other manner. Furthermore, the multiple battery cells 5 may be secured together using fasteners.

[0205] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0206] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules. Those skilled in the art may select an appropriate number based on the application and capacity of the battery pack.

[0207] Figures 6 and 7 illustrate an example battery pack 1. Referring to Figures 6 and 7 , the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be positioned over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0208] In addition, the present application also provides an electrical device, which includes the secondary battery provided in the present application. The secondary battery can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device can include, but is not limited to, mobile devices, electric vehicles, electric trains, ships, satellites, energy storage systems, etc. Among them, mobile devices can be, for example, mobile phones, laptops, etc.; electric vehicles can be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc., but are not limited to these.

[0209] As an electrical device, a secondary battery can be selected according to its usage requirements.

[0210] FIG8 shows an example of an electric device 6. The electric device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the electric device's requirements for high power and high energy density of secondary batteries, a battery pack or battery module may be used.

[0211] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is generally required to be lightweight and thin, and may use a secondary battery as a power source.

[0212] Below, the embodiment of the present application is described. The embodiment described below is exemplary, is only used to explain the present application, and is not to be construed as limiting the present application. Where the technology or conditions are not specified in the embodiment, the technology or conditions described in the literature in this area or the product instructions are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially.

[0213] Example 1

[0214] (1) Preparation of composite current collector

[0215] The passivating agent potassium dichromate is evenly coated on the surface of the thick conductive layer with a thickness of 5 μm by gravure coating to form a passivation layer with a thickness of 100 nm. The conductive layer is an aluminum layer.

[0216] A 6 μm thick PET (polyethylene terephthalate) film was corona treated to obtain a support layer by making the dyne value of both surfaces of the PET film in the thickness direction be 42 and the roughness be 0.15 μm.

[0217] Polyurethane glue was applied on both surfaces of the support layer in the thickness direction, and then baked in an oven at 110°C to form a bonding layer with a thickness of 500 nm.

[0218] The passivated thick conductive layer is stacked on both surfaces of the support layer in the thickness direction, pressed (pressing temperature is 100°C), and aged at a temperature of 85±5°C to obtain a composite current collector with a thick conductive layer.

[0219] The thick conductive layer was corroded to a thickness of 1000 nm by a sodium hydroxide etching thinning process, thereby obtaining a composite current collector with a final conductive layer thickness of 1000 nm.

[0220] The roughness of the surface of the conductive layer away from the support layer is controlled to be 1.2 μm through an etching thinning process.

[0221] (2) Preparation of secondary batteries

[0222] (2.1) Preparation of positive electrode sheet

[0223] The positive electrode active material NCM 811 , conductive carbon black SP and binder PVDF are dispersed in solvent NMP in a weight ratio of 98:1:1 and mixed evenly to obtain a positive electrode slurry; the positive electrode slurry is evenly coated on the double-sided surface of the composite current collector prepared in the above step (1), and after drying and cold pressing, a positive electrode sheet is obtained. The compaction density of the positive electrode sheet is 3.4g / cm 3 .

[0224] (2.2) Preparation of negative electrode sheet

[0225] The negative electrode active material graphite, thickener sodium carboxymethyl cellulose, binder styrene butadiene rubber, and conductive agent acetylene black were mixed in a mass ratio of 97:1:1:1, and deionized water was added to obtain a negative electrode slurry under the action of a vacuum mixer; the negative electrode slurry was evenly coated on both sides of the copper foil; the copper foil was dried at room temperature and then transferred to a 120°C oven for drying for 1 hour, and then super-cold pressed and cut to obtain a negative electrode sheet. The compaction density of the negative electrode sheet was 1.6 g / cm 3 .

[0226] (2.3) Isolation membrane

[0227] Use a separator with PP laminated on both sides of PE (PP / PE / PP).

[0228] (2.4) Preparation of electrolyte

[0229] The organic solvent is a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC), with a volume ratio of 30:70. In an argon atmosphere glove box with a water content of <10 ppm (parts per million), fully dried lithium salt LiPF6 is dissolved in the organic solvent and mixed thoroughly to obtain an electrolyte solution. The concentration of the lithium salt is 1 mol / L (mole / liter).

[0230] (2.5) Preparation of batteries

[0231] The positive electrode sheet, separator and negative electrode sheet are stacked in order, so that the separator is placed between the positive and negative electrode sheets to play an isolating role. After winding into a bare battery cell, the double-sided metal edging method is used to roller weld the electrode ears, and then fill them with aluminum-plastic film. After baking at 80°C to remove water, non-aqueous electrolyte is injected and sealed. After standing, hot and cold pressing, formation, clamping, capacity division and other processes, the finished battery is obtained.

[0232] Examples 2-24

[0233] The method is basically the same as Example 1, except that the preparation method of the composite current collector in step (1) is different, specifically, the composition and thickness of the bonding layer and the composition and thickness of the passivation layer are changed, see Table 1 for details.

[0234] Example 25

[0235] The process is basically the same as Example 1, except that the preparation method of the composite current collector in step (1) is different.

[0236] The preparation method of the composite current collector in this embodiment is as follows:

[0237] A passivation agent, potassium dichromate, and polyurethane adhesive were prepared into a slurry in a mass ratio of 1:1. The slurry was coated on the surface of a 5 μm thick conductive layer and then baked in an oven at 110°C to form a 700 nm thick bonding layer.

[0238] A PET film having a thickness of 6 μm was subjected to corona treatment so that the dyne value of both surfaces of the PET film in the thickness direction was 42 and the roughness was 0.15 μm, thereby obtaining a support layer;

[0239] The passivated thick conductive layer is stacked on both surfaces of the support layer in the thickness direction, pressed (pressing temperature is 100°C), and aged at a temperature of 85±5°C to obtain a composite current collector with a thick conductive layer.

[0240] The thick conductive layer was corroded to a thickness of 1000 nm by a sodium hydroxide etching thinning process, thereby obtaining a composite current collector with a final conductive layer thickness of 1000 nm.

[0241] The roughness of the surface of the conductive layer away from the support layer is controlled to be 1.2 μm through an etching thinning process.

[0242] Examples 26-43

[0243] The method is basically the same as Example 1, except that the preparation method of the composite current collector in step (1) is different, specifically, the composition and thickness of the bonding layer are changed, see Table 1 for details.

[0244] Comparative Example 1

[0245] Basically the same as Example 1, except that: the preparation method of the composite current collector in step (1) is different;

[0246] The preparation method of the composite current collector in this comparative example is as follows:

[0247] A PET film having a thickness of 6 μm was subjected to corona treatment so that the dyne value of both surfaces of the PET film in the thickness direction was 42 and the roughness was 0.15 μm, thereby obtaining a support layer;

[0248] A conductive layer was prepared on both surfaces of the support layer in the thickness direction by the evaporation method. The thickness of the conductive layer on one side was 1000 nm. Then, the size of the deposited grains was changed by controlling the number of evaporation passes and the wire feeding speed during evaporation, so that the roughness of the surface of the conductive layer away from the support layer was 1.2 μm.

[0249] The binder and passivating agent used in the composite current collectors prepared in Examples 1-43 can be obtained commercially.

[0250] The product parameters of the composite current collectors prepared in Examples 1-43 and Comparative Example 1 are shown in Tables 1 and 2.

[0251] Product parameter testing and performance testing

[0252] (1) Test method for the molar ratio of isocyanate groups to hydroxyl groups

[0253] (1.1) Test method for isocyanate groups

[0254] The content of isocyanate groups in the binder was tested using potentiometric titration. The specific steps are as follows: weigh 0.2g to 0.3g of sample into a 250mL beaker, add 10mL of chloroform to dissolve the sample, and then use a pipette to accurately add 20.00mL of 0.2mol / L hexahydropyridine chlorobenzene solution. After 30 minutes of complete reaction, add 150mL of anhydrous ethanol, then perform magnetic stirring, insert a reference electrode and a composite electrode, and under constant stirring, perform potentiometric titration with a 0.1mol / L hydrochloric acid standard solution. Record the corresponding volume and pH as the titrant is added. When approaching the endpoint, record the corresponding pH value after each continuous increase (0.1mL) of titrant is added. Stop when the pH changes slowly; perform a blank test at the same time. W1(%) = (V0-V1)*C*4.202 / m Formula I

[0255] In formula I, W1 is the mass percentage of isocyanate groups in the binder, V1 is the standard volume of HCl consumed in the blank experiment (mL), V0 is the standard volume of HCl 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.

[0256] (1.2) Test method for hydroxyl groups

[0257] Using toluenesulfonic acid as a catalyst, acetic anhydride and hydroxyl groups are acetylated in ethyl acetate. Excess acetic anhydride is hydrolyzed with a mixture of pyridine and water, and the generated acetic acid is titrated with a standard sodium hydroxide solution to calculate the content of hydroxyl groups in the binder.

[0258] The specific steps are as follows: Place a sample (approximately 145 / estimated hydroxyl value; if the estimated hydroxyl value is 70 mgKOH / g, then 145 / 70 = 2 g) into a 250 mL iodine flask. Add 10 mL of acetylating agent, cap the flask, and heat in a (50 ± 2)°C water bath. Shake to dissolve the sample evenly, then heat at 50°C for 20 minutes (shaking every few minutes). Remove the iodine flask and cool. Rinse the flask mouth, flask stopper, and flask walls with 10 mL to 20 mL of a 3:1 (volume ratio) pyridine:water hydrolysis solution. Allow to stand for 5 minutes 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 titrant until a pink color appears. The endpoint is reached if the color does not fade after 15 seconds. Perform a blank test simultaneously using the same method. Qv = 56.1*(V3-V2)c / m0+Av (Formula II)

[0259] In formula II, Qv is the hydroxyl value of the sample (mgKOH / g); V2 is the volume of the sodium hydroxide standard solution consumed in the titration blank (mL); V3 is the volume of the sodium hydroxide standard solution consumed in the titration sample (mL); c is the concentration of the sodium hydroxide standard titration solution (mol / L); m0 is the mass of the sample (g); 56.1 is the molar mass of potassium hydroxide (g / mol); and Av is the acid value of the sample (mg KOH / g).

[0260] According to W1 and Qv obtained in steps (1.1) and (1.2), the molar ratio of isocyanate groups to hydroxyl groups in the binder is calculated.

[0261] (2) Testing method for thickness of each layer

[0262] The composite current collector cross-section sample is prepared using liquid nitrogen quenching or argon ion etching, and the secondary electron phase morphology of the sample cross-section is observed using a scanning electron microscope (1000-30000 times) with a minimum resolution of nanometers, and the thickness of the support layer, bonding layer, passivation layer or conductive layer is measured.

[0263] (3) Testing methods for phosphorus, chromium, and materials in the conductive layer

[0264] The elemental analysis was performed using ICP (inductively coupled plasma) method.

[0265] (4) Testing method for peeling force between support layer and conductive layer

[0266] After laminating the composite current collector to the non-corona surface of the EAA (ethylene acrylic acid copolymer) film, 12μm PET is covered on the EAA film and laminated on a heat sealer at a temperature of 120°C and a pressure of 0.2MPa. The laminated sample is cut into 100mm (millimeter) long and 20mm wide samples, and the non-laminated surface of the conductive layer is attached to a steel plate with 3M double-sided tape; the sample is clamped in the fixture of a tensile testing machine and subjected to a 180°C peel test at a spacing of 50mm and a speed of 300mm / min (millimeter / minute). The peel force is read and converted into N / m. Five groups of parallel samples are tested, and the average peel force of the five groups of parallel samples is finally taken.

[0267] (5) Testing method for the peeling force between the support layer and the conductive layer after the composite current collector is soaked in electrolyte

[0268] The composite current collector was cut into 30mm×10mm samples, placed in an aluminum-plastic film, and encapsulated with 20g of electrolyte. After immersion at 60℃, the sample was taken out after 72h for peeling force test. After the sample was bonded to the non-corona surface of the EAA film, 12μm PET was covered on the EAA film and bonded on a heat sealer with a temperature of 120℃ and a pressure of 0.2MPa. The bonded sample was cut into 100mm long and 20mm wide samples, and the non-bonded surface of the conductive layer was attached to the steel plate with 3M double-sided tape; the sample was clamped on the fixture of the tensile testing machine and subjected to a 180℃ peeling test at a spacing of 50mm and a speed of 300mm / min. The peeling force was read and converted into N / m. Three groups of parallel samples were tested, and the average peeling force of the three groups of parallel samples was finally taken.

[0269] The peeling force 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.

[0270] Table 1

[0271] In Table 1, “ / ” indicates that the substance or parameter does not exist.

[0272] Table 2

[0273] Table 3

[0274] It can be seen from Tables 1 to 3 that no bonding layer is provided 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 peeling force 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 collectors are soaked in electrolyte, the peeling force between the support layer and the conductive layer is also relatively high. This indicates that the support layer and the conductive layer of the composite current collectors of Examples 1-43 of the present application are connected by a bonding layer, which 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 electrolyte.

[0275] The above description of the various embodiments tends to emphasize the differences between the various embodiments. The same or similar aspects can be referenced with each other and will not be repeated herein for the sake of brevity.

[0276] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A composite current collector, comprising a support layer, a bonding layer and a conductive layer, wherein the bonding layer and the conductive layer are sequentially stacked on two opposite surfaces of the support layer and in a direction away from the support layer.

2. The composite current collector according to claim 1, wherein: The bonding layer contains a bonding agent, which includes one or more of a bonding composition, polyurethane, epoxy resin, polyacrylate, polyvinyl acetate, unsaturated polyester, phenolic resin, urea-formaldehyde resin, polyolefin resin, silicone resin, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, acrylic resin, polycarbonate and polyamide, and the bonding composition includes isocyanate and polyester polyol.

3. The composite current collector according to claim 2, wherein: The adhesive comprises one or more of the adhesive composition and the polyurethane.

4. The composite current collector according to claim 2 or 3, wherein: 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.

5. The composite current collector according to claim 4, wherein: The molar ratio of the isocyanate group to the hydroxyl group is 0.9-1.

6. The composite current collector according to any one of claims 1 to 5, wherein: The peeling force between the support layer and the conductive layer is ≥150 N / m.

7. The composite current collector according to any one of claims 1 to 6, wherein: The peeling force between the support layer and the conductive layer is 150 N / m to 600 N / m.

8. The composite current collector according to any one of claims 2 to 7, wherein: Based on the mass of the adhesive layer, the mass proportion of the adhesive is 50% to 100%.

9. The composite current collector according to any one of claims 2 to 8, wherein: The thickness of the bonding layer is 200nm to 1500nm.

10. The composite current collector according to any one of claims 2 to 9, wherein: The thickness of the bonding layer is 300nm-700nm.

11. The composite current collector according to any one of claims 2 to 10, wherein: The bonding layer further comprises a passivator, and the mass ratio of the bonding agent to the passivator is 1 to 2.

5.

12. The composite current collector according to claim 11, wherein: The mass ratio of the binder to the passivator is 1.2-2.

13. The composite current collector according to any one of claims 1 to 12, wherein: The composite current collector further includes a passivation layer, which is disposed between the bonding layer and the conductive layer, and contains a passivating agent.

14. The composite current collector according to claim 13, wherein: The passivation layer has one or more of the following features: (1) The ratio of the thickness of the bonding layer to the thickness of the passivation layer is ≥ 1; (2) The thickness of the passivation layer is 1 nm to 500 nm.

15. The composite current collector according to any one of claims 11 to 14, wherein: The passivating agent includes one or more of organic phosphates, chromates, dichromates, Al2O3, SiO2 and Si3N4.

16. The composite current collector according to claim 15, wherein: The passivating agent 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 proportion of phosphorus element and / or chromium element is ≤0.3%.

17. The composite current collector according to any one of claims 1 to 16, wherein: The support layer has one or more of the following features: (1) The dyne value of the surface of the support layer close to the bonding layer is ≥40; (2) The roughness of the surface of the support layer close to the bonding layer is ≥0.1 μm.

18. The composite current collector according to any one of claims 1 to 17, wherein: The roughness of the surface of the conductive layer on a side away from the bonding layer is 0.1 μm to 2 μm.

19. The composite current collector according to any one of claims 1 to 18, wherein: The thickness of the conductive layer is 500nm to 2500nm.

20. The composite current collector according to any one of claims 1 to 19, wherein: The conductive layer includes a conductive material, and based on the mass of the conductive layer, the mass proportion of the conductive material is ≥99.5%.

21. The composite current collector according to any one of claims 1 to 20, wherein: The thickness of the support layer is 2 μm to 40 μm.

22. The composite current collector according to any one of claims 1 to 21, wherein: The support layer comprises one or more of a polymer material and a polymer-based composite material; The polymer-based composite material comprises the polymer material and an additive, wherein the additive comprises one or more of a metal material and an inorganic non-metal material.

23. The method for preparing the composite current collector according to any one of claims 1 to 22, comprising the following steps: The bonding layer and the conductive layer are sequentially stacked on two opposite surfaces of the support layer and in a direction away from the support layer.

24. The preparation method according to claim 23, wherein: The step of forming the adhesive layer and the conductive layer stacked in sequence comprises: A first slurry containing a binder is disposed on a surface of at least one of the support layer and the conductive layer, and the first slurry is cured to form the bonding layer.

25. The preparation method according to claim 24, wherein: The first slurry further includes a passivator, and the mass ratio of the binder to the passivator in the first slurry is 1 to 2.

5.

26. The preparation method according to any one of claims 23 to 25, wherein: The step further includes: forming a passivation layer between the bonding layer and the conductive layer; The step of forming the passivation layer includes: disposing a second slurry containing a passivator on one surface of the conductive layer, and curing the second slurry to form the passivation layer.

27. The preparation method according to claim 25 or 26, wherein: The passivating agent includes one or more of organic phosphates, chromates, dichromates, Al2O3, SiO2 and Si3N4.

28. An electrode plate, comprising at least one of the composite current collector according to any one of claims 1 to 22 and the composite current collector prepared by the preparation method according to any one of claims 23 to 27.

29. A battery comprising the composite current collector according to any one of claims 1 to 22 or the electrode plate according to claim 28.

30. An electrical device comprising the battery according to claim 29.

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