Negative pole piece, battery and electric device

Abstract

The invention discloses a negative electrode piece, a battery and a power utilization device, the negative electrode piece comprises a negative electrode current collector and a negative electrode active layer arranged on the surface of one side of the negative electrode current collector, the negative electrode current collector comprises a polymer base material layer, a viscous layer and an ultrathin copper foil which are sequentially stacked, and the thickness of the ultrathin copper foil is 0.8-4.5 [mu] m; the tensile strength of the negative current collector is greater than or equal to 180 Mpa, and the elongation at break is greater than or equal to 5%. The negative pole piece has the advantages of lightness, thinness, good mechanical property and the like, is used for preparing a battery, can make the battery lighter and thinner, further improves the energy density of the battery, and is further used for an electric device.

Description

Technical Field

[0001] The present application relates to the field of new energy technology, and more specifically, to a negative electrode plate, a battery, and an electrical device. Background Art

[0002] Lithium battery is a rechargeable battery that mainly relies on the migration of lithium ions between positive and negative electrodes to achieve charging and discharging. It has the advantages of high energy density, small size and long cycle life. It is widely used in consumer electronics, new energy vehicles and energy storage.

[0003] A pole piece consists of a current collector and an active layer disposed on its surface. A pole piece with an active layer on one side of the current collector is called a single-sided pole piece, while a pole piece with active layers on both sides of the current collector is called a double-sided pole piece. Single-sided pole pieces use less material, have lower costs, and lower energy density, making them more suitable for batteries used in low-power products such as handheld appliances, wearable electronics, and smart homes. Bifacial pole pieces, with active material on both sides, can increase capacity and energy density, making them suitable for batteries used in high-energy-density, high-power products such as electric vehicles, power tools, and drones.

[0004] During rolling, single-sided pole pieces can exhibit significant curvature or distortion due to the significant difference in ductility between the current collector and the active layer, severely impacting the subsequent winding process. Traditional single-sided pole pieces typically utilize thicker current collectors than double-sided pole pieces, while also reducing the compaction density of the single-sided pole piece to avoid distortion. This approach not only increases material costs and the difficulty of the production process, but also increases the thickness of the battery, sacrificing its energy density.

[0005] Furthermore, for the negative electrode sheet, copper foil is usually used to prepare the negative electrode current collector. In order to maintain the mechanical strength of the negative electrode current collector, the copper foil used is relatively thick, usually 6μm to 15μm. Since the density of copper is very high (about 8.96g / cm 3 ), such a design results in the current collector accounting for too high a proportion of weight in the battery, compressing the proportion of active materials, further limiting the improvement of battery energy density, and urgently needs to be improved. Summary of the Invention

[0006] Based on this, the present application provides a thin and light negative electrode sheet with good mechanical properties for use in preparing batteries, which can make the battery thinner and lighter, thereby improving the energy density of the battery, and further be used in electrical devices.

[0007] The technical solution of the present application is a negative electrode plate, comprising a negative electrode current collector and a negative electrode active layer arranged on a single side surface of the negative electrode current collector, wherein the negative electrode current collector comprises a polymer substrate layer, an adhesive layer and an ultra-thin copper foil stacked in sequence, wherein the thickness of the ultra-thin copper foil is 0.8μm to 4.5μm; the tensile strength of the negative electrode current collector is ≥180Mpa, and the elongation at break is ≥5%.

[0008] In one embodiment, the thickness of the polymer substrate layer is 1 μm to 6 μm.

[0009] In one embodiment, the material of the polymer substrate layer is one or more of polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polyimide (PI), polyamide (PA), polyester (PC), polyvinyl chloride (PVC), polystyrene (PS), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polybutylene terephthalate (PBT), acrylonitrile-styrene copolymer (SAN), acrylonitrile-butadiene-styrene terpolymer (ABS), polyarylsulfone (PASF), polyethylene naphthalate (PEN), poly-3,4-ethylenedioxythiophene (PEDOT), polyaniline (PANI) and polypyrrole (PPy).

[0010] In one embodiment, the thickness of the adhesive layer is 0.2 μm to 4 μm.

[0011] In one embodiment, the curing shrinkage of the adhesive layer is ≤3%.

[0012] In one embodiment, the bonding force between the adhesive layer and the polymer substrate layer is 3N / 25mm to 30N / 25mm.

[0013] In one embodiment, the bonding force between the adhesive layer and the ultra-thin copper foil is 3N / 25mm to 30N / 25mm.

[0014] In one embodiment, the adhesive layer is formed by curing an adhesive liquid, and the adhesive liquid comprises component A and component B; wherein the component A comprises a combination of one or more of polyurethane resin, acrylic resin, epoxy resin, polyester resin, polyimide, silicone polymer and modified compounds thereof; the component B comprises a combination of one or more of amino resin, isocyanate, aziridine crosslinking agent, carbodiimide, silane coupling agent and silicone tackifier; the weight ratio of the component A to the component B is (90-99): (1-5).

[0015] In one embodiment, the tensile strength of the ultra-thin copper foil is ≥300 MPa, and the elongation at break is ≥3%.

[0016] In one embodiment, the ultra-thin copper foil is produced by electrolysis, and the electroplating solution used in the electrolysis includes a mother solution and an additive, and the additive includes a combination of one or more of protein and hydroxyethyl cellulose.

[0017] In one embodiment, the additive includes, based on the concentration in the electroplating solution: 20 ppm to 60 ppm of protein component, the protein component includes proteins of different molecular weights, the molecular weights of the proteins of different molecular weights are gradually distributed within the range of [molecular weight Min, molecular weight Max], and the proportions of proteins of different molecular weights are uniform.

[0018] In one embodiment, the molecular weight Min is ≥ 180, and the molecular weight Max is ≤ 10,000.

[0019] In one embodiment, the protein component includes one or more combinations of collagen, gelatin, peptone and protein peptide.

[0020] In one embodiment, the additive comprises, based on the concentration in the electroplating solution, 20 ppm to 60 ppm of a hydroxyethyl cellulose mixture, wherein the hydroxyethyl cellulose mixture comprises hydroxyethyl cellulose of different viscosities.

[0021] In one embodiment, the hydroxyethyl cellulose mixture comprises at least hydroxyethyl celluloses of different viscosities with a viscosity difference of at least 1000 mPa·s.

[0022] In one embodiment, the viscosity of each hydroxyethyl cellulose is independently 15000 mPa·s to 100000 mPa·s.

[0023] In one embodiment, the mother liquor comprises:

[0024] Cu 2+ 65g / L~90g / L;

[0025] H2SO4 75g / L~100g / L;

[0026] Cl - 20ppm~30ppm.

[0027] In one embodiment, the surface density of the negative electrode active layer is 25 g / m 2 ~200g / m 2 .

[0028] In one embodiment, the compaction density of the negative electrode active layer is 0.8 g / cm 3 ~2.0g / cm 3 .

[0029] In one embodiment, the thickness of the negative electrode current collector is 3 μm to 12 μm.

[0030] The present application also provides a battery, comprising a positive electrode plate, a separator and the negative electrode plate as described above.

[0031] In one embodiment, the battery is an ultra-thin battery.

[0032] In one embodiment, the positive electrode plate includes a positive electrode current collector and a positive electrode active layer provided on a single side surface of the positive electrode current collector.

[0033] In one embodiment, the surface density of the positive electrode active layer is 50 g / m 2 ~350g / m 2 .

[0034] In one embodiment, the compaction density of the positive electrode active layer is 2.0 g / cm 3 ~4.0g / cm 3 .

[0035] The present application also provides an electrical device, which includes the battery as described above, and the battery provides electrical energy for the electrical device.

[0036] This application has at least the following beneficial effects:

[0037] The present application provides a single-sided negative electrode sheet, comprising a negative electrode current collector having a specific structure and performance and a negative electrode active layer arranged on a single side surface of the negative electrode current collector, wherein the negative electrode current collector comprises a polymer substrate layer, an adhesive layer and an ultra-thin copper foil (thickness of 0.8μm to 4.5μm) stacked in sequence. The polymer substrate and ultra-thin copper foil are stably bonded to form a laminated composite structure through an adhesive layer, giving the negative electrode current collector the advantages of both ultra-thin copper foil and polymer substrate. While reducing weight and thickness, and significantly reducing production costs, the negative electrode current collector also possesses excellent mechanical properties, with a tensile strength of ≥180 MPa and an elongation at break of ≥5%. This can prevent subsequent battery production problems such as broken strips during coating or warping or distortion during subsequent sheeting. Furthermore, the lightweight negative electrode current collector, combined with the negative electrode active layer disposed on a single surface, can significantly reduce the weight and thickness of the negative electrode sheet, thereby reducing the weight and thickness of the battery and increasing the battery's energy density. This makes it suitable for low-power scenarios such as handheld appliances, wearable electronics, and smart homes, broadening the application range of ultra-thin copper foil. Furthermore, the negative electrode sheet and battery also offer advantages such as safety, stability, simple preparation methods, and low production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the structure of the negative electrode current collector shown in one embodiment of the present application;

[0039] Figure 2 This is a schematic structural diagram of a negative electrode sheet according to an embodiment of the present application;

[0040] Figure 3 This is a schematic diagram of the molecular weight distribution of a uniformly distributed protein according to an embodiment of the present application;

[0041] Figure 4 This is a scanning electron microscope image of a composite copper foil (negative electrode current collector) with a total thickness of about 6 μm shown in an embodiment of the present application;

[0042] Figure 5 This is a schematic structural diagram of a battery according to an embodiment of the present application;

[0043] Figure 6 The discharge curves of lithium batteries prepared with composite copper foil and pure copper foil as negative electrode current collectors at a current of 0.2C are shown in an embodiment of the present application;

[0044] Figure 7 The discharge curves of lithium batteries prepared with composite copper foil and pure copper foil as negative electrode current collectors at a current of 0.5C are shown in an embodiment of the present application;

[0045] Figure 8 The discharge curves of a lithium battery prepared with a 1C current using a composite copper foil and a pure copper foil as the negative electrode current collector as shown in an embodiment of the present application;

[0046] Explanation of reference numerals: negative electrode current collector 100 , polymer substrate layer 110 , adhesive layer 120 , ultra-thin copper foil 130 , negative electrode plate 10 , negative electrode active layer 200 , battery 1 , separator 20 , positive electrode plate 30 . DETAILED DESCRIPTION

[0047] The technical solutions of the present application will be described clearly and completely below in conjunction with the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are only some of the embodiments of the present application, not all of them, and are only used to illustrate the present application and should not be considered to limit the scope of the present application. In addition, the drawings are not drawn at a 1:1 scale, and the relative sizes of the various elements in the drawings are only drawn as examples to facilitate understanding of the present invention, but are not necessarily drawn according to the actual scale. The scales in the drawings do not constitute a limitation of the present invention.

[0048] The specific embodiments and accompanying drawings of this application are intended for illustrative purposes only and are not to be construed as limiting the present application. The present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided for the purpose of providing a more thorough and comprehensive understanding of the disclosure of this application.

[0049] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in this application and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0050] In this application, "and / or" includes any and all combinations of one or more related listed items. "Including", "having", and "comprising" described in this application are intended to cover non-exclusive inclusions. Unless clear limiting terms such as "only", "consisting of...", etc. are used, another component may be added.

[0051] In the present application, “preferably”, “more preferably”, “preferably”, “better”, etc. refer to embodiments of the present application that may provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the statement of one or more preferred embodiments does not imply that other embodiments are not available, nor is it intended to exclude other embodiments from the scope of the present application. That is, in the present application, “preferably”, “more preferably”, “preferably”, “better”, etc. are merely descriptions of implementation methods or examples with better effects, but do not constitute a limitation on the scope of protection of the present application. Similarly, “further”, “further”, “particularly”, etc. are only used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of protection of the present application.

[0052] In the present application, "A and B are independently selected from x, y or z" means that A and B are independent events, and event A does not affect the occurrence of event B. Therefore, when A is selected from x, B can be selected from any one of x, y or z; when A is selected from y, B can be selected from any one of x, y or z; when A is selected from z, B can be selected from any one of x, y or z.

[0053] When a numerical range is disclosed in this application, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed in this application should be understood to include any and all subranges subsumed therein.

[0054] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0055] In this application, “above” or “below” includes the number itself. For example, “1 below” includes 1.

[0056] In the present application, room temperature refers to 0°C to 60°C, including but not limited to 10°C to 40°C, or further 20°C to 30°C.

[0057] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one of the features.

[0058] In this application, "multiple" or "several" means at least two, such as two, three, etc., unless otherwise specifically defined. "Several" means at least one, such as one, two, three, etc., unless otherwise specifically defined. "At least one" means any one, any two, or any two or more. Unless otherwise specified, a term in the singular may include the plural form and is not to be construed as meaning one.

[0059] In the present application, directional words such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and should not be understood as limiting the specific scope of protection of the present application.

[0060] In this application, when describing positional relationships, unless otherwise specified, when an element, such as a layer, film, or substrate, is referred to as being "on" another layer, it can be directly on the other layer or intervening layers may be present. Furthermore, when a layer is referred to as being "under" another layer, it can be directly under or one or more intervening layers may be present. It is also understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers or one or more intervening layers may be present.

[0061] In the present application, molecular weight Min represents the minimum molecular weight, molecular weight Max represents the maximum molecular weight Max, and [molecular weight Min, molecular weight Max] represents the interval between the minimum molecular weight and the maximum molecular weight Max, including molecular weight Min and molecular weight Max.

[0062] In this application, the test method for the elongation at break of a material is well known to those skilled in the art and is not limited thereto. For example, the test method may refer to GB / T29847-2013, SJ / T 11483-2014, or GB / T1040.3-2006. The test instrument may use a universal tensile testing machine (also known as a universal material testing machine or a tensile testing machine) to test the tensile strength and elongation at break of the sample.

[0063] In the present application, the viscosity of hydroxyethyl cellulose is a 2 w % aqueous solution of the corresponding hydroxyethyl cellulose, measured by a Brook viscometer at 25° C., and the unit is mPa·s.

[0064] During actual rolling, single-sided pole pieces experience significant curvature or distortion due to uneven force on both sides, seriously impacting the winding process. Traditional single-sided pole pieces typically use thicker current collectors than double-sided pole pieces, while also reducing the compaction density of the single-sided pole piece to avoid distortion. This approach not only increases material costs and the difficulty of the production process, but also increases the thickness of the battery, sacrificing its energy density.

[0065] The metal foil used for battery negative electrode current collectors is typically copper foil. Currently, the mainstream electrolytic copper foil on the market has a thickness of 6 μm or greater, a tensile strength of 330 MPa or greater, and an elongation at break of 3.0% to 4.0%. As the thickness of the copper foil decreases, its mechanical properties and processability decline significantly. During transportation, storage, handling, placement, and lamination, the foil is prone to wrinkling, scratches, dents, or pits on the copper surface. During the coating and roller-pressing process of the battery active material, it is prone to bulges, holes, and even fractures (tape breakage). This not only affects battery safety but also increases manufacturing costs. For electrolytic ultra-thin or ultra-thin copper foils with a thickness of less than 4.5 μm, especially those with a thickness of less than or equal to 3.5 μm, the application range is very narrow and difficult to use in the battery field, especially for single-sided pole pieces. Improvements are urgently needed.

[0066] Based on this, the present application provides a thin and light negative electrode sheet with good mechanical properties. The technical solution is as follows: a negative electrode sheet, comprising a negative electrode collector and a negative electrode active layer arranged on a single side surface of the negative electrode collector, the negative electrode collector comprising a polymer substrate layer, an adhesive layer and an ultra-thin copper foil stacked in sequence, wherein the thickness of the ultra-thin copper foil is 0.8μm to 4.5μm; the tensile strength of the negative electrode collector is ≥180Mpa, and the elongation at break is ≥5%.

[0067] The polymer substrate and the ultra-thin copper foil are stably bonded to a stacked composite copper foil structure through a sticky layer, so that the negative electrode current collector has the advantages of both ultra-thin copper foil and substrate. Compared with pure copper foil negative electrode current collector, the composite copper foil negative electrode current collector of the present application not only reduces weight and thinness and greatly reduces production costs, but also gives the negative electrode current collector excellent mechanical properties and processability, which can avoid the subsequent battery active material coating and reduce the subsequent undesirable phenomena such as warping or twisting deformation. In addition, by combining the lightweight negative electrode current collector with the negative electrode active layer arranged on its single-side surface, the weight and thickness of the negative electrode sheet can be significantly reduced, thereby reducing the weight and thickness of the battery and improving the energy density of the battery. It is suitable for low-power scenarios such as handheld appliances, wearable electronics and smart homes.

[0068] For example, the schematic diagram of the composite copper foil negative electrode current collector can be found in Figure 1 , Figure 1 The composite current collector 100 includes a polymer substrate layer 110 , an adhesive layer 120 , and an ultra-thin copper foil 130 , which are stacked in sequence.

[0069] For example, the schematic diagram of the negative electrode plate can be found in Figure 2 , Figure 2 The middle negative electrode sheet 10 includes a negative electrode current collector 100 and a negative electrode active layer 200 provided on a single side surface of the negative electrode current collector.

[0070] In one embodiment, the tensile strength of the ultra-thin copper foil is ≥300 MPa, and the elongation at break is ≥3%.

[0071] In one embodiment, the ultra-thin copper foil has a thickness of 3 μm to 4.5 μm, a tensile strength of ≥300 MPa, and an elongation at break of ≥3.0%.

[0072] In one embodiment, the ultra-thin copper foil has a thickness of 3 μm to 4.5 μm, a tensile strength of 300 MPa or greater, and an elongation at break of 3.5% or greater. Furthermore, the ultra-thin copper foil has a thickness of 3 μm to 4.5 μm, a tensile strength of 320 MPa to 500 MPa, and an elongation at break of 3.5% or greater.

[0073] In one embodiment, the ultra-thin copper foil has a thickness of 3 μm to 4 μm, a tensile strength of 300 MPa or greater, and an elongation at break of 3.0% or greater. Furthermore, the ultra-thin copper foil has a thickness of 3 μm to 4 μm, a tensile strength of 320 MPa to 370 MPa, and an elongation at break of 3.5% or greater.

[0074] In one embodiment, the ultra-thin copper foil has a thickness of 3 μm to 3.5 μm, a tensile strength of ≥300 MPa, and an elongation at break of ≥3%.

[0075] In one embodiment, the ultra-thin copper foil has a thickness of 2 μm to 3 μm, a tensile strength of ≥250 MPa, and an elongation at break of ≥3%. Furthermore, the ultra-thin copper foil has a thickness of 2 μm to 3 μm, and a tensile strength of 250 MPa to 340 MPa.

[0076] In one embodiment, the ultra-thin copper foil has a thickness of 1 μm to 3 μm, a tensile strength of ≥200 MPa, and an elongation at break of ≥2.5%.

[0077] In one embodiment, the ultra-thin copper foil is produced by electrolysis, and the electroplating solution used in the electrolysis includes a mother liquor and an additive, wherein the additive includes a combination of one or more of protein and hydroxyethyl cellulose. The protein additive hinders the discharge of copper ions, thereby refining the copper grains, making the surface of the copper foil smoother, reducing the surface roughness, and promoting the formation of a specific crystal plane preferred orientation of the copper foil, or improving the density of the electrolytic ultra-thin copper foil through the complex network structure of hydroxyethyl cellulose and copper ions, thereby significantly improving the mechanical properties of the electrolytic ultra-thin copper foil, so that the copper foil still has good mechanical properties (such as some ultra-thin copper foils with a thickness of 3μm to 4μm, a tensile strength of ≥300Mpa, and an elongation at break of ≥3%) and processability when the thickness is less than 4.5μm.

[0078] In one embodiment, the additive comprises, based on the concentration in the plating solution, 20ppm to 60ppm of a protein component, wherein the protein component comprises proteins of different molecular weights, the molecular weights of the proteins of different molecular weights are gradually distributed within the range of [molecular weight Min, molecular weight Max], and the proportions of the proteins of different molecular weights are uniform. For example, the protein components used in one embodiment have different molecular weight proteins and their quantity distribution as shown in FIG. Figure 3 shown.

[0079] Furthermore, the molecular weight of proteins of different molecular weights may increase in a step-wise manner; further, the difference (error) in the percentage of proteins of different molecular weights in the protein fraction is less than or equal to 10%; the percentage refers to the percentage of the protein fraction as a whole. Furthermore, the molecular weight is the weight-average molecular weight Mw.

[0080] Since conventional proteins commonly added to electrolyte solutions are mostly derived from direct enzymatic hydrolysis of specific collagen, the protein composition is generally concentrated in a certain molecular weight range or a certain range of proteins, and is formed by other molecular weight proteins with a smaller proportion. The proportion of proteins of different molecular weights is arranged in a single peak structure. For example, in the molecular weight range of [1000, 3000], the proportion of proteins of a certain molecular weight range (such as 2500-2700) is greater than 60%, and the proportion of proteins of other molecular weights is less than 10%. However, the present application creatively proposes to use different molecular weight proteins with similar quantities in the distribution range as additives to the electrolyte solution. For example, in the range of [1000, 3000], proteins of different molecular weights of 1000, 1300, 1600, 2100, 2500, and 2900 are mixed, and the proportion of each molecular weight protein is basically similar or equal, such as (the quantity) is between 13% and 20%. (It should be understood by those skilled in the art that due to technical limitations or unstable factors, a small proportion within the error range may be allowed. This endpoint value is also for example only). After adding this type of protein component as one of the additive components, the inventors of the present application found that compared to traditional proteins with molecular weights concentrated in a certain value / a certain molecular weight distribution, the use of the protein of the present application with a uniform molecular weight distribution and a uniform proportion as an additive significantly improved the mechanical properties of the electrolytic ultra-thin copper foil, which was significantly better than the traditional protein additives. It can significantly improve the elongation at break and tensile strength of the corresponding electrolytic ultra-thin copper foil. The inventors speculate that this is because the adsorption sites of single molecular weight proteins are limited, so the improvement of mechanical properties on the formed copper layer is limited. When different molecular weight proteins are used in a uniform proportion, they can provide uniform adsorption and binding at multiple sites, thereby further improving the flatness of the ultra-thin copper foil and the corresponding elongation at break and tensile strength.

[0081] In one embodiment, the molecular weight Min is ≥ 180, and the molecular weight Max is ≤ 10000. Furthermore, the difference between the molecular weight Max and the molecular weight Min is ≥ 1800. Furthermore, protein components within different molecular weight distribution widths can be used as additives, and this application does not impose any special restrictions on this. For example, [molecular weight Min, molecular weight Max] can be [1000, 3000], [3000, 5000] or [5000, 10000]. In one embodiment, this application uses proteins of different molecular weights to be evenly and equally distributed in the interval [1000, 3000], and the ultra-thin copper foil obtained by electrolysis has excellent mechanical properties.

[0082] In one embodiment, the protein component includes one or more combinations of collagen, gelatin, peptone and protein peptide.

[0083] In one embodiment, the additive comprises, based on the concentration in the electroplating solution, 20 ppm to 60 ppm of a hydroxyethyl cellulose mixture, wherein the hydroxyethyl cellulose mixture comprises hydroxyethyl cellulose of different viscosities.

[0084] When the hydroxyethyl cellulose mixture containing different viscosity hydroxyethyl cellulose is added in the electroplating solution containing copper ion, the compactness, tensile strength of the ultra-thin copper foil produced by electrolysis are further enhanced. It is speculated that it may be due to containing different viscosities (understandably, viscosity is relevant to molecular weight, and different viscosities in this application can be regarded as different molecular weights) hydroxyethyl cellulose in the hydroxyethyl cellulose mixture, along with the combination of hydroxyethyl cellulose and copper ion, different molecular weight hydroxyethyl celluloses i.e. realize the combination between copper ions in different directions and different distances, the hydroxyethyl cellulose of different molecular weights can be connected to form a complex copper ion distribution network, form a complex structure that is widely distributed and copper ion is dense, and then significantly improve compactness, stability of the ultra-thin copper foil obtained by electrolysis, collaborate to enhance the tensile strength and the elongation at break of the ultra-thin copper foil of electrolysis. On the other hand, after connecting, improving the compactness of the ultra-thin copper foil of electrolysis in conjunction with copper ion by hydroxyethyl cellulose, pinhole quantity can be significantly reduced and ultra-thin copper foil transmittance can be reduced.

[0085] It is understood that the viscosity of the hydroxyethyl cellulose mixture can be adjusted by changing the proportion of hydroxyethyl cellulose with different viscosities.

[0086] In one embodiment, the viscosity of each hydroxyethyl cellulose is independently 15000 mPa·s to 100000 mPa·s, including but not limited to 15000 mPa·s, 20000 mPa·s, 24000 mPa·s, 25000 mPa·s, 30000 mPa·s, 35000 mPa·s, 40000 mPa·s, 45000 mPa·s, 50000 mPa·s, 55000 mPa·s, 60000 mPa·s, 65000 mPa·s, 70000 mPa·s, 75000 mPa·s, 80000 mPa·s, 85000 mPa·s, 90000 mPa·s, 95000 mPa·s or 100000 mPa·s. The hydroxyethyl cellulose component of the above viscosity can better connect and combine copper ions, thereby facilitating the improvement of the density of the corresponding electrolytic ultra-thin copper foil obtained, reducing pinholes, lowering light transmittance, etc., and significantly improving the corresponding tensile strength.

[0087] In one embodiment, the hydroxyethyl cellulose mixture includes at least hydroxyethyl celluloses of different viscosities with a viscosity difference of at least 1000 mPa·s. Furthermore, the hydroxyethyl cellulose mixture includes at least hydroxyethyl celluloses of different viscosities with a viscosity difference of at least 3000 mPa·s. When the different hydroxyethyl celluloses have a certain degree of viscosity / molecular weight difference, it facilitates cross-linking of copper ions over a wider distance range, forming a complex and extensive cross-linking network, further improving the density and stability of the resulting ultra-thin copper foil, thereby increasing the tensile strength of the electrolytic ultra-thin copper foil.

[0088] In one embodiment, the hydroxyethyl cellulose mixture is formed by mixing two or more hydroxyethyl celluloses having viscosities of 20,000 mPa·s, 24,000 mPa·s, 30,000 mPa·s, and 90,000 mPa·s. The combination of these hydroxyethyl celluloses significantly improves the mechanical properties of the electrolytic ultra-thin copper foil.

[0089] In one embodiment, the additive described in the present application is compounded by a protein component and a hydroxyethyl cellulose mixture. For example, in terms of concentration in the electroplating solution, the additive includes: 20ppm to 60ppm of protein component and 20ppm to 60ppm of hydroxyethyl cellulose mixture. Through the coordinated effect of the protein component and the hydroxyethyl cellulose mixture, the performance of the ultra-thin copper foil obtained by electrolysis can be improved in many aspects, including flatness, density, tensile strength, elongation at break and surface gloss, etc., to prepare an electrolytic ultra-thin copper foil with excellent comprehensive performance. Even if the thickness of the ultra-thin copper foil is less than 4.5μm, or even less than 3.5μm, it still has good mechanical properties and processability.

[0090] In one embodiment, the additive further includes, based on the concentration in the electroplating solution, 5 ppm to 20 ppm of a brightener. The brightener can be used to adjust the brightness of the copper foil surface, inhibit impurity formation, and ensure the weather resistance of the coating.

[0091] In one embodiment, the brightener comprises a combination of one or more of a sulfur-containing organic brightener, 4-phenylimidazole, 2-benzylimidazolidine, hexylbenzylamine salt, and diphenylvinylpyridine. Further, the sulfur-containing organic brightener comprises one or more of the group consisting of: sodium polydisulfide propane sulfonate (SPS), sodium thiazolinyl disulfide propane sulfonate, sodium trimethylformamide sulfonate, sodium N,N-dimethyldithioformamide propane sulfonate, sodium 3-mercapto-1-propane sulfonate, sodium diphenylamine sulfonate, L-dithiothreitol, sodium 3-(phenylthiazole-2-mercapto) propane sulfonate, sodium 2-hydroxy-3-mercaptosulfurate, tetrahydrothiazolidinethione, sodium phenyl polydisulfide propane sulfonate, sodium alcoholthiopropane sulfonate, sodium ethyldithiocarbonate propyl sulfonate, thiourea, polyisothiourea propane sulfonic acid inner salt, or 2-hydroxyphenylthiourea.

[0092] In one embodiment, the additive further includes a wetting agent at a concentration of 5 ppm to 20 ppm in the electroplating solution. The wetting agent helps the electroplating liquid better cover the workpiece surface, reduces bubble formation, and promotes uniform distribution of the electroplating solution, thereby improving the uniformity and quality of the coating.

[0093] In one embodiment, the wetting agent includes one or more of polyethylene glycol (PEG), octylphenol polyoxyethylene ether (OPE) or polypropylene glycol (PPG).

[0094] In one embodiment, the additives include a brightener and a wetting agent, wherein the brightener is sodium polydisulfide dipropylene sulfonate and the wetting agent is polyethylene glycol.

[0095] In one embodiment, the additive also includes a leveling agent to improve the surface flatness of the copper foil, refine the grain size, promote preferred crystal orientation, reduce warpage, enhance oxidation resistance and corrosion resistance, and improve mechanical properties and processing performance. Furthermore, the additive includes 0.01 ppm to 20 ppm of the leveling agent, measured at a concentration in the electroplating solution.

[0096] In one embodiment, the leveling agent includes one or more of the group consisting of nitrogen-containing organic leveling agents or agarose. Furthermore, the nitrogen-containing organic compound leveling agent includes one or more of the group consisting of diaminopolyethylene glycol or amine organic compounds. Furthermore, the amine organic compound includes one or more of the group consisting of Janus green, polyethyleneimine compounds, 1,1-dimethylpropargylamine, alkylated polyethyleneimine, quaternary ammonium salts, benzotriazole, or arginine. Furthermore, the polyethyleneimine compound includes one or more of the group consisting of polyethyleneimine, polyethyleneimine alkyl compounds, N-acetylethyleneimine, polyethyleneimine alkane, or ethoxypolyethyleneimine.

[0097] In one embodiment, the mother liquor comprises:

[0098] Cu 2+ 65g / L~90g / L;

[0099] H2SO4 75g / L~100g / L;

[0100] Cl - 20ppm~30ppm.

[0101] The electroplating solution containing the aforementioned additives can form an electrolytic copper foil with improved mechanical properties as the electrolysis process proceeds. Furthermore, the overall system is relatively stable, effectively leveraging the effects of the electroplating solution mother solution and the additives.

[0102] In one embodiment, the method for preparing the electrolytic ultra-thin copper foil comprises the following steps:

[0103] S100, preparing an electroplating solution and supplying the electroplating solution between the anode structure and the cathode structure;

[0104] S200, at a plating temperature of 45°C to 55°C, and a current density of 40A / dm 2 ~70A / dm 2 Under the conditions, the electroplating solution is circulated to electrolyze the foil to obtain the corresponding electrolytic ultra-thin copper foil;

[0105] In step S100 , a plating mother solution is first prepared, and then the additives described above are adaptively added to the plating mother solution to prepare an electroplating solution.

[0106] It can be understood that the anode structure may be an anode plate, the cathode structure may be a cathode plate or a cathode roller, and the electrolytic copper foil production process may be a continuous plating process.

[0107] In one embodiment, the surface roughness of the ultra-thin copper foil is Ra≤0.3μm; however, the ultra-thin copper foil also has a certain surface roughness. In addition to directly improving the conductive performance, it can promote the formation of a mechanical bite interface between the ultra-thin copper foil and the adhesive layer, thereby enhancing the bonding between the ultra-thin copper foil and the adhesive layer.

[0108] In one embodiment, the thickness of the polymer substrate layer is 1 μm to 6 μm. Furthermore, the thickness of the polymer substrate layer is 1.9 μm to 5 μm. Furthermore, the thickness of the polymer substrate layer is 3 μm to 5 μm.

[0109] In one embodiment, the material of the polymer substrate layer is a combination of one or more of polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polyimide (PI), polyamide (PA), polyester (PC), polyvinyl chloride (PVC), polystyrene (PS), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polybutylene terephthalate (PBT), acrylonitrile-styrene copolymer (SAN), acrylonitrile-butadiene-styrene terpolymer (ABS), polyarylsulfone (PASF), polyethylene naphthalate (PEN), poly-3,4-ethylenedioxythiophene (PEDOT), polyaniline (PANI) and polypyrrole (PPy). Further, the material of the polymer substrate layer is a combination of one or more of PET, PP and PI. Further, the material of the polymer substrate layer is a combination of one or more of PET and PP. Exemplarily, the material of the polymer substrate layer is PET.

[0110] In one embodiment, the curing shrinkage of the adhesive layer is ≤3%, and it has excellent heat resistance. The adhesive layer in this application can achieve adhesion between the substrate layer and the ultra-thin copper foil, overcoming the instability of direct bonding between the polymer substrate layer and the ultra-thin copper foil; at the same time, it can also effectively prevent shrinkage during the curing stage, preventing the shrinkage from causing the substrate layer and the ultra-thin copper foil to deform and shrink, facilitating the maintenance of the planar shape to closely fit the polymer substrate layer and the copper foil plane; and it can also prevent the coverage area of ​​the adhesive layer from shrinking after shrinkage, ensuring the adhesive action area and improving the bonding strength. Furthermore, the curing shrinkage of the adhesive layer is ≤2%; furthermore, the curing shrinkage of the adhesive layer ranges from 0.1% to 0.5%. For example, the thermal shrinkage of the adhesive layer in this application is tested according to the JISC2151 specification.

[0111] In one embodiment, the bonding force between the adhesive layer and the polymer substrate layer is 3N / 25mm to 30N / 25mm, which makes the composite copper foil negative electrode current collector structure very stable.

[0112] In one embodiment, the bonding force between the adhesive layer and the ultra-thin copper foil is 3N / 25mm to 30N / 25mm, which makes the composite copper foil negative electrode current collector structure very stable.

[0113] In one embodiment, the thickness of the adhesive layer is 0.2 μm to 4 μm. Further, the thickness of the adhesive layer is 0.2 μm to 3 μm. Further, the thickness of the adhesive layer is 0.5 μm to 2.5 μm.

[0114] It is understandable that in the present application, the polymer substrate layer can be directly bonded to the copper foil via an adhesive layer to form a negative electrode current collector. Compared to forming copper foil on the surface of the polymer substrate layer by methods such as magnetron sputtering or water electroplating, the present application utilizes the adhesive properties of the adhesive layer to directly composite the copper foil and the polymer substrate layer to form a negative electrode current collector. The process is simpler and faster, does not require complex and expensive production equipment, and is easy to achieve mass production, overcoming the problem of difficult mass production of composite copper foil or negative electrode current collectors. It is understandable that the adhesive layer can be a pre-formed semi-cured layer structure, which is directly composited with the polymer substrate layer and ultra-thin copper foil; it can also be formed by applying an adhesive liquid on the surface of the substrate layer to form a viscous layer, and further composited with the ultra-thin copper foil.

[0115] It can be understood that the adhesive layer is formed by curing an adhesive liquid, and the adhesive liquid can be derived from commercial products, such as commercial polyurethane glue, acrylic resin glue, epoxy resin glue and UV curing glue, or can be homemade.

[0116] In one embodiment, the adhesive layer is formed by curing an adhesive liquid, and the adhesive liquid comprises component A and component B; wherein the component A comprises a combination of one or more of polyurethane resin, acrylic resin, epoxy resin, polyester resin, polyimide, silicone polymer and modified compounds thereof; the component B comprises a combination of one or more of amino resin, isocyanate, aziridine crosslinking agent, carbodiimide, silane coupling agent and silicone tackifier; the weight ratio of the component A to the component B is (90-99): (1-5).

[0117] Illustratively, the component A is compounded from a polyurethane resin, a polyimide and a modified silicone polymer.

[0118] In one embodiment, the polyurethane resin in component A has a polyester backbone portion and a polyether backbone portion, and the mass ratio of the polyester backbone portion to the polyether backbone portion in the polyurethane resin is in the range of (1:9) to (5:5); the polyester backbone can be formed by a polyester polyol compound, which is formed by low molecular weight polyols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, neopentyl glycol, 1,2 Compounds produced by reacting 1,3-butanediol, 1,4-butanediol, 3-methylpentanediol, 1,6-hexanediol, hydrogenated bisphenol A, trimethylolpropane, and glycerol with polybasic acids such as succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, tetrahydrophthalic acid, methylene-terminated tetrahydrophthalic acid, and hexahydrophthalic acid have an ester structure and terminal hydroxyl groups. The polyether backbone can be formed from a polyether polyol, preferably a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms (such as ethylene oxide, propylene oxide, and butylene oxide) to a diol containing a bisphenol backbone. Examples of the diol containing a bisphenol backbone include methylene bisphenol, ethylidene bisphenol, butylidene bisphenol, and isopropylidene bisphenol. The number of moles of alkylene oxide added is preferably 1 to 10.

[0119] In one embodiment, the amino resin in component B can be selected from commercially available Cytec 216, Cytec 301, Cytec 303, Cytec 327, Cytec 325, Cytec 370, Cytec 385, Cytec 659, Cytec 683, Cytec 1156, Cytec 1123, Cytec MM-100, INEOS 717, INEOS 718, INEOS R747, INEOS R757, INEOS 917, INEOS MF927, INEOS MF984, INEOS MF985, INEOS MF986, INEOS MF988, INEOS M195, INEOS MR921, INEOS CE7103, INEOS CE8824, OS 303-98, OS At least one of 325-80, methyl etherified amino resin 5717W, fully methyl etherified amino resin MR603, MELCROSS-83, Changxing ETERMINO9411, and ETE RMINO9412; other amino resins may also be used.

[0120] In one embodiment, the temperature range for the gel setting stage during the adhesive layer curing process is 80°C to 90°C, and the temperature range for the post-compounding aging stage is 50°C to 90°C. Specifically, after the adhesive layer is laminated with the substrate layer and copper foil, it is placed at 50°C to 90°C for 24 to 48 hours to mature to obtain the negative electrode current collector. This aging process can fully utilize the adhesive layer and improve the composite effect.

[0121] In one embodiment, the adhesive liquid further comprises a filler component C, wherein the weight ratio of component A, component B, and filler component C is: (90-99): (1-5): (1-5). Further, the filler component C comprises a combination of one or more of silicon dioxide, aluminum hydroxide, aluminum oxide, talc, aluminum nitride, boron nitride, silicon carbide, barium sulfate, barium titanate, strontium titanate, boehmite, calcium carbonate, calcium silicate, mica, magnesium oxide, magnesium hydroxide, kaolin, starch, montmorillonite, titanium dioxide, zinc sulfide, calcium bicarbonate, calcium phosphate, calcium hydrogen phosphate, calcium sulfate, carbon black, graphite, multi-walled and single-walled carbon nanotubes, carbon nanofibers, polytetrafluoroethylene particles, polyurethane particles, rubber particles, polyamide particles, silicone particles, graphene, nanotube structures, and antimony trioxide.

[0122] In one embodiment, the thickness of the negative electrode current collector is 3 μm to 12 μm. Furthermore, the thickness of the negative electrode current collector is 3 μm to 8 μm.

[0123] Testing has shown that the composite copper foil negative electrode current collectors described in some embodiments of this application have a tensile strength of 180 MPa or greater, and an elongation at break of 5% or greater. Furthermore, the composite copper foil negative electrode current collectors described in some embodiments of this application have a tensile strength of 200 MPa or greater, and an elongation at break of 5% or greater. Furthermore, the composite copper foil negative electrode current collectors described in some embodiments of this application have a tensile strength of 250 MPa or greater, and an elongation at break of 6% or greater.

[0124] In one embodiment, the method for preparing the composite copper foil negative electrode current collector as described above comprises the following steps:

[0125] The polymer substrate and the ultra-thin copper foil are laminated together through an adhesive layer to prepare the composite copper foil negative electrode current collector.

[0126] Compared with forming composite copper foil on the surface of a polymer substrate layer by magnetron sputtering or water electroplating, or first preparing a composite copper foil containing a thick layer of copper and then thinning the thick layer of copper, the present application utilizes the adhesive properties of the adhesive layer to directly composite ultra-thin or ultra-thin copper foil with a polymer substrate layer to form a composite copper foil. The process is simpler and faster, does not require complex and expensive production equipment, and is easy to achieve mass production, overcoming the problem of difficult mass production of composite copper foil.

[0127] In one embodiment, the adhesive layer may be a pre-formed semi-cured layer structure, which is directly laminated with the polymer substrate layer and the ultra-thin copper foil.

[0128] In one embodiment, an adhesive liquid is first coated on the surface of the polymer substrate layer to form an adhesive layer, which is then further laminated with an ultra-thin copper foil.

[0129] In one embodiment, an adhesive liquid is first coated on the surface of the ultra-thin copper foil to form an adhesive layer, which is then further laminated with a polymer substrate layer.

[0130] It can be understood that the present application has no special restrictions on the negative electrode active layer. For example, the components, dosage, layer thickness, surface density and compaction density of the negative electrode active layer can be set according to conventional requirements in the field.

[0131] In one embodiment, the negative electrode active layer includes a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder. Furthermore, the weight ratio of the negative electrode active material, the negative electrode conductive agent, and the negative electrode binder is (80-99.9):(0.001-20):(0.001-20).

[0132] In one embodiment, the negative electrode active material comprises a combination of one or more of carbon-based materials, silicon-based materials, alloy materials, lithium titanate materials, and metallic lithium. Furthermore, the negative electrode active material may be selected from, but not limited to, artificial graphite, natural graphite, soft carbon, hard carbon, mesocarbon microbeads, graphene, carbon fibers, carbon nanotubes, elemental silicon, silicon oxides, silicon-carbon composites, lithium titanate, or a combination of one or more of these materials with transition metals or non-transition metals added thereto. Exemplarily, the negative electrode active material is artificial graphite.

[0133] In one embodiment, the negative electrode conductive agent can be a conductive material commonly used in the art, including but not limited to at least one of graphite, carbon nanotubes, nanofibers, carbon black, and graphene. Furthermore, the negative electrode conductive agent can be selected from a combination of one or more of SP, KS-6, acetylene black, Ketjen Black (ECP), SFG-6, vapor-grown carbon fiber (VGCF), carbon nanotubes (CNTs), graphene, and composite conductive agents thereof. Exemplarily, the negative electrode conductive agent is SP.

[0134] In one embodiment, the negative electrode binder may be a binder commonly used in the art, including but not limited to: a combination of 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). Exemplarily, the negative electrode binder is SBR.

[0135] In one embodiment, the negative electrode active layer may further include other additives, such as a thickener, such as sodium carboxymethyl cellulose (CMC-Na). Based on the total weight of the negative electrode active layer, the weight proportion of the other additives in the negative electrode active layer is 0 to 15 wt%. Furthermore, the weight proportion of the thickener in the negative electrode active layer is 0.001 wt% to 5 wt%.

[0136] In one embodiment, the surface density of the negative electrode active layer is 25 g / m 2 ~200g / m 2 Furthermore, the surface density of the negative electrode active layer is 50g / m 2 ~100g / m 2 Furthermore, the surface density of the negative electrode active layer is 50g / m 2 ~80g / m 2 Furthermore, the surface density of the negative electrode active layer is 55g / m 2 ~75g / m 2 .

[0137] In one embodiment, the compaction density of the negative electrode active layer is 0.8 g / cm 3 ~2.0g / cm 3 Furthermore, the compaction density of the negative electrode active layer is 1.0 g / cm 3 ~1.8g / cm 3 Furthermore, the compaction density of the negative electrode active layer is 1.2 g / cm 3 ~1.8g / cm 3 .

[0138] It can be understood that the present application has no special restrictions on the preparation method of the negative electrode sheet, and it can be prepared according to conventional methods in the art.

[0139] In one embodiment, the method for preparing the negative electrode sheet includes the following steps:

[0140] Dispersing the above-mentioned components for preparing the negative electrode sheet, such as the modified negative electrode active material, the negative electrode conductive agent, the negative electrode binder and the additives, in a solvent (such as deionized water) to form a negative electrode slurry;

[0141] The negative electrode slurry is coated on the negative electrode current collector, and after drying and roller pressing processes, the negative electrode sheet is prepared.

[0142] In one embodiment, the method for preparing the negative electrode sheet includes the following steps:

[0143] The components for preparing the negative electrode sheet, such as the negative electrode active material, the negative electrode conductive agent, the negative electrode binder and the additives, are mixed by a dry process to form a negative electrode mixture;

[0144] The negative electrode mixture is coated on the negative electrode current collector and rolled to prepare the negative electrode sheet.

[0145] The present application also provides a battery comprising a positive electrode sheet, a separator, and the negative electrode sheet as described above. The battery has the advantages of being light and thin, having high energy density, good cycle performance, and being safe and reliable.

[0146] In one embodiment, the battery is a lithium battery.

[0147] In one embodiment, the positive electrode plate is a single-sided plate, comprising a positive electrode current collector and a positive electrode active layer provided on a single side surface of the positive electrode current collector.

[0148] It can be understood that the present application has no special restrictions on the positive electrode current collector and the positive electrode active layer. For example, the material and thickness of the positive electrode current collector, the components, dosage, layer thickness, surface density and compaction density of the positive electrode active layer can all be set according to conventional requirements in the field.

[0149] In one embodiment, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.). Exemplarily, the positive electrode current collector is aluminum foil.

[0150] In one embodiment, the positive electrode active layer includes a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder. Furthermore, the weight ratio of the positive electrode active material, the positive electrode conductive agent, and the positive electrode binder is (80-99.9):(0.001-20):(0.001-20).

[0151] In one embodiment, the positive electrode active material may be a positive electrode active material commonly used in the art, such as a lithium ion positive electrode active material. Further, the lithium ion positive electrode active material is selected from a combination of one or more of lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. Among them, examples of lithium transition metal oxides may include but are not limited to lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (NCM), lithium nickel cobalt aluminum oxide (NCA), lithium iron phosphate, lithium manganese phosphate and lithium manganese iron phosphate. Exemplarily, the positive electrode active material is a lithium nickel cobalt manganese oxide ternary positive electrode material.

[0152] In one embodiment, the positive electrode conductive agent can be a conductive material commonly used in the art, including but not limited to at least one of graphite, carbon nanotubes, nanofibers, carbon black, and graphene. Furthermore, the positive electrode conductive agent can be selected from a combination of one or more of SP, KS-6, acetylene black, Ketjen black ECP, SFG-6, vapor-grown carbon fiber (VGCF), carbon nanotubes (CNTs), graphene, and composite conductive agents thereof. Exemplarily, the positive electrode conductive agent is SP.

[0153] In one embodiment, the positive electrode binder can be a binder commonly used in the art, including but not limited to: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, hydrogenated nitrile rubber, styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), carboxymethyl chitosan (CMCS) and a fluorine-containing acrylate resin. Exemplarily, the positive electrode binder is PVDF.

[0154] In one embodiment, the surface density of the positive electrode active layer is 50 g / m 2 ~350g / m 2 Furthermore, the surface density of the positive electrode active layer is 100g / m 2 ~250g / m 2 Furthermore, the surface density of the positive electrode active layer is 100g / m 2 ~200g / m 2 Furthermore, the surface density of the positive electrode active layer is 105 g / m 2 ~130g / m 2 .

[0155] In one embodiment, the compaction density of the positive electrode active layer is 2.0 g / cm 3 ~4.0g / cm 3 Furthermore, the compaction density of the positive electrode active layer is 2.8 g / cm 3 ~3.6g / cm 3 Furthermore, the compaction density of the positive electrode active layer is 2.9 g / cm 3 ~3.5g / cm 3 Furthermore, the compaction density of the positive electrode active layer is 3.0 g / cm 3 ~3.3g / cm 3 .

[0156] It is understandable that the present application has no special restrictions on the preparation method of the positive electrode sheet, and it can be prepared according to conventional methods in the art.

[0157] In one embodiment, the method for preparing the positive electrode sheet includes the following steps:

[0158] Dispersing the above components for preparing the positive electrode sheet in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry;

[0159] The positive electrode slurry is coated on the current collector, and after drying and roller pressing processes, the positive electrode sheet is prepared.

[0160] In one embodiment, the method for preparing the positive electrode sheet includes the following steps:

[0161] The components for preparing the positive electrode sheet, such as the positive electrode active material, the positive electrode conductive agent, and the positive electrode binder, are mixed by a dry process to form a positive electrode mixture;

[0162] The positive electrode mixture is coated on the positive electrode current collector and rolled to prepare the positive electrode sheet.

[0163] It can be understood that the diaphragm is arranged between the positive electrode plate and the negative electrode plate. This application does not impose any special restrictions on the type and layer thickness of the diaphragm. A conventional diaphragm with good chemical stability and mechanical stability in the field can be selected, and the thickness can be set according to the conventional requirements in the field.

[0164] In one embodiment, the separator comprises a combination of one or more of polypropylene, polyethylene, polyethylene terephthalate, cellulose, polyimide, polyamide, spandex, and aramid. Exemplarily, the separator is a composite film of polypropylene and polyethylene.

[0165] It is understood that the battery described in this application may include not only a positive electrode plate, a separator, and a negative electrode plate, but also a battery electrolyte. Furthermore, this application does not impose any particular restrictions on the composition and concentration of the battery electrolyte.

[0166] In one embodiment, the battery electrolyte includes an electrolyte salt and a solvent. The present application does not impose any particular limitation on the types of the electrolyte salt and the solvent.

[0167] In one embodiment, the electrolyte salt includes but is not limited to: a combination of one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorophosphate, lithium difluorodioxalatophosphate and lithium tetrafluorooxalatophosphate.

[0168] In one embodiment, the solvent includes but is not limited to: ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), dibutyl carbonate (DBC), ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dioxolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. One or more combinations thereof.

[0169] In one embodiment, the concentration of the electrolyte salt is 0.5 mol / L to 2 mol / L. Further, the concentration of the electrolyte salt is 0.5 mol / L to 1.5 mol / L. Further, the concentration of the electrolyte salt is 1.0 mol / L to 1.5 mol / L.

[0170] It is understood that the battery electrolyte may also optionally include functional additives. For example, the functional 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.

[0171] As will be understood, the battery further includes a housing for packaging the positive electrode sheet, negative electrode sheet, separator, and electrolyte. For example, the housing can be a hard shell, such as a hard plastic shell, aluminum shell, or steel shell; or a soft shell, such as a bag-type soft shell, made of plastic, further including polypropylene, polybutylene terephthalate, and polybutylene succinate; or the housing can be an aluminum-plastic film.

[0172] The present application does not impose any particular limitation on the shape of the battery, which may be cylindrical, square, or any other shape. In one embodiment, the battery is a square battery.

[0173] At present, electronic products are developing in the direction of miniaturization, portability and ultra-thinness. Batteries are the key components of electronic products. To achieve the lightness and thinness of electronic products, the problem of ultra-thin batteries must be solved first. This application uses ultra-thin copper foil for the negative electrode current collector to prepare a single-sided electrode, which significantly reduces the weight and thickness of the electrode, and can further prepare ultra-thin batteries. Compared with traditional square batteries, which are limited by the winding process and module structure, the thickness is generally above 40mm, resulting in low volume utilization and uneven heat dissipation. The ultra-thin battery provided by this application can overcome the defects of traditional square batteries, and has the advantages of being green and environmentally friendly, having a long cycle life, low self-consumption, and not catching fire or exploding in the case of over-discharge, short circuit, puncture, thermal shock, and heavy object impact. Furthermore, the thickness of the ultra-thin battery described in this application is 0.5mm to 1.0mm.

[0174] The present application also provides an electrical device, which includes the battery as described above, and the battery provides electrical energy for the electrical device.

[0175] In one embodiment, the electrical device needs to be able to continuously collect information, thus requiring battery energy storage to provide a long battery life. Furthermore, to provide greater user comfort and convenience, the electrical device must be compact and lightweight. Furthermore, some electrical devices come into close contact with the user, making product safety particularly important. The battery described in this application offers advantages such as lightness, high energy density, excellent cycle performance, and safety and reliability, providing excellent overall performance that can simultaneously meet these requirements.

[0176] Exemplarily, power-consuming devices include low-power products such as lighting equipment, handheld appliances, wearable electronics, and smart homes. Exemplarily, power-consuming devices include, but are not limited to, lighting equipment, AR / VR / MR headsets, smart audio glasses, Bluetooth headsets, wearable speakers, smart watches, smart bracelets, smart rings, phone cards, bank cards, smart cards, information cards, smart clothing (such as heated clothing), smart shoes, smart belts, smart bandages, portable sensors, smart tags, smart door locks, cameras, remote controls, medical devices, or tracking devices.

[0177] 1. Test method:

[0178] (1) Surface density of copper foil or composite copper foil: Weigh the copper foil and calculate the surface density of the copper foil by calculating the ratio of the copper foil mass to the area. Calculate the surface density of the composite copper foil by calculating the ratio of the composite copper foil mass to the area. The unit is g / m 2 .

[0179] (2) Copper foil square resistance: The copper foil square resistance is tested using an HPS2523 coating true current resistance tester at room temperature. The unit is mΩ.

[0180] (3) The mechanical properties test method of copper foil or negative electrode current collector (composite copper foil) refers to GB / T29847-2013, and the testing instrument is Dongguan Sitai ST-D200.

[0181] (4) Thickness of lithium battery: GH-D electronic thickness gauge.

[0182] (5) The electrical performance test method of lithium batteries is as follows:

[0183] ①Capacity and energy test methods:

[0184] Weigh the lithium battery and record the battery weight M0. Charge it to 4.3V at 0.2C constant current at 25±2℃, then charge it to a cutoff current of 0.02C at constant voltage, and then discharge it to a cutoff voltage of 3.0V at 0.2C constant current. The discharge capacity is recorded as C.0.2 , the discharge energy is recorded as W0, and the energy density = W0 / M0.

[0185] ②Rate performance test method:

[0186] 0.5C capacity retention rate: Charge the battery to 4.3V at 0.2C constant current at 25±2℃, then charge it to a cutoff current of 0.02C at constant voltage, and then discharge the battery to a cutoff voltage of 3.0V at 0.5C constant current. The discharge capacity is recorded as C 0.5 , 0.5C capacity retention rate = (C 0.5 / C 0.2 )*100%;

[0187] 1C capacity retention rate: Charge the battery to 4.3V at 0.2C constant current at 25±2℃, then charge it to a cut-off current of 0.02C at constant voltage, and then discharge it to a cut-off voltage of 3.0V at 1C constant current. The discharge capacity is recorded as C1, and 1C capacity retention rate = (C1 / C 0.2 )*100%.

[0188] ③Battery testing system: Ningbo BT5V30AC32-32AT.

[0189] 2. Ingredients:

[0190] (1) Electrolytic ultra-thin copper foil can be purchased or made by yourself. The method of making electrolytic ultra-thin copper foil by yourself is as follows:

[0191] S100, preparing an electroplating solution according to the formula in Table 1, and supplying the electroplating solution between the anode plate and the cathode roller;

[0192] S200, at a plating temperature of 45°C to 55°C, and a current density of 40A / dm 2 ~70A / dm 2 The plating solution was circulated under the following conditions to electrolyze the foil to obtain ultra-thin copper foil of corresponding thickness (it can be understood that the thickness refers to the average thickness, which is limited by the measurement method and has an error within the acceptable range in this field). The performance test of the obtained electrolytic ultra-thin copper foil was then carried out. The performance test results of each group of ultra-thin copper foil are shown in Table 2 below.

[0193] Table 1

[0194]

[0195] The proteins used are collagen (P) and hydroxyethyl cellulose (HEC, unit is mPa·s). Specifically, the protein component 1 (P1) comprises proteins with different molecular weights distributed and uniformly distributed in the range of [1000, 3000] ([1000, 1500], [1500, 2000], [2000, 2500], and [2500, 3000], all accounting for 20% to 30%); the protein component 2 (P2) comprises proteins with a weight average molecular weight of [1000, 5000] ([1000, 2000], [2000, 3000], [2500, 3000], all accounting for 20% to 30%). The invention relates to a hydroxyethyl cellulose composition comprising proteins of different molecular weights uniformly distributed in the range of 0.30% to 30% (the proportions are 20% to 30%); the hydroxyethyl cellulose 1 (HEC1) is a hydroxyethyl cellulose mixture formed by mixing hydroxyethyl celluloses having viscosities of 24000 mPa·s and 30000 mPa·s in a weight ratio of 1:1; the hydroxyethyl cellulose 2 (HEC2) is a hydroxyethyl cellulose mixture formed by mixing hydroxyethyl celluloses having viscosities of 30000 mPa·s and 90000 mPa·s in a weight ratio of 1:1, and "-" indicates that no addition is made.

[0196] Table 2

[0197]

[0198]

[0199] As shown in Table 2, for copper foil of the same thickness, the use of a uniformly distributed protein component or hydroxyethyl cellulose mixture as an electroplating bath additive significantly improves the tensile strength and elongation at break of the resulting ultra-thin copper foil. Combining the protein component with the hydroxyethyl cellulose mixture further significantly enhances the mechanical properties. Furthermore, the ultra-thin copper foil exhibits low sheet resistance and excellent electrical properties, meeting industry requirements.

[0200] (2) The adhesive can be purchased or homemade. The commercially available product is Yantai polyurethane glue TS-9015. The homemade adhesive is made by mixing components A, B and C in a weight ratio of 93:3:3, and the dispersion medium is water. Component A is compounded by commercially available water-based polyurethane dispersion, commercially available polyimide and commercially available polyether polyester modified organosiloxane. The weight ratio of water-based polyurethane dispersion to polyimide is 3:2, and the weight proportion of polyether polyester modified organosiloxane in component A is 0.2%. Component B is commercially available Cytec 303 amino resin, and filler component C is commercially available graphite.

[0201] Component A, component B, and component C were coated on a release film in a weight ratio of 93:3:3 to prepare adhesive layers of different thicknesses. During the curing process, the temperature of the gel setting stage was 80°C, the temperature of the aging stage was 70°C, and the time was 40 hours. The specific thickness and performance test results are shown in Table 3 below.

[0202] Table 3

[0203]

[0204] As can be seen from Table 3, the adhesive layer has a low curing shrinkage and excellent heat resistance.

[0205] (3) The polymer substrate is PET substrate, and PET of different thicknesses are all from commercial products.

[0206] (4) The negative electrode active layer is made of artificial graphite, conductive carbon black, CMC-Na and SBR, and the raw materials are all commercially available.

[0207] (5) Positive electrode: The commercially available ternary positive electrode is a single-sided electrode.

[0208] (6) Diaphragm: PP-PE-PP composite diaphragm, commercially available.

[0209] (7) Battery electrolyte: ternary battery electrolyte, sourced from the market.

[0210] Example 1

[0211] Example 1 provides Figure 1 The negative electrode current collector 100 shown includes a polymer substrate layer 110, an adhesive layer 120, and an ultra-thin copper foil 130 stacked together, as follows:

[0212] A commercially available glue, or the above-mentioned component A, component B and filler component C in a weight ratio of 93:3:3 was used as a bonding liquid to bond the PET substrate to a portion of the electrolytic ultra-thin copper foil in Table 1 to prepare a negative electrode current collector with a total thickness of approximately 6 μm to 6.5 μm as shown in Table 4 (it can be understood that the current collector thickness refers to the average thickness, which is limited by the measurement method and has an error within the acceptable range in this field. The adhesive layers not described in Table 4 are all the adhesive layers shown in Table 3). The commercially available glue was cured at room temperature; the temperature of the gel setting stage during the curing process of the homemade adhesive layer 120 was 80 to 60°C. 90 ° C, the adhesive layer 120 is compounded with the polymer substrate layer 110 and the copper foil 130, and then placed at 70 ° C to 80 ° C for 24 h to 48 h for aging to obtain negative electrode current collectors 100 (composite current collectors) with multi-layer composite structures No. 1 to 13. Commercially available 6 μm copper foil is used as the negative electrode current collector No. 14. The performance test results of each negative electrode current collector are shown in Table 4 below, where the adhesion 1 refers to the adhesion between the adhesive layer and the substrate layer, and the adhesion 2 refers to the adhesion between the adhesive layer and the copper foil, and the unit is N / 25 mm; in addition, the electron microscope image of the negative electrode current collector structure with a total thickness of about 6 μm is shown in Figure 4 .

[0213] Table 4

[0214]

[0215]

[0216] As can be seen from Table 4, the present application stacks a polymer substrate layer, an adhesive layer, and an ultra-thin copper foil with specific mechanical properties to prepare a composite copper foil negative electrode current collector. The negative electrode current collector has the advantages of both ultra-thin copper foil and polymer substrate, and it also gives the negative electrode current collector excellent mechanical properties while reducing weight and thickness and significantly reducing production costs.

[0217] Example 2

[0218] Example 2 provides Figure 2 The negative electrode sheet 10 shown is a single-sided sheet, comprising the negative electrode current collectors 100 No. 1 to 13 shown in Example 1 and the negative electrode active layer 200 provided on a single side of the negative electrode current collector 100, as well as another negative electrode sheet 10', which differs from the negative electrode sheet 10 in that it uses the commercially available 6 μm pure copper foil No. 14 shown in Table 4 as the negative electrode current collector, as shown in Table 4.

[0219] Artificial graphite, SP, SBR and CMC-Na were dispersed in deionized water in a weight ratio of 93:5:2.5:0.8 to form a negative electrode slurry;

[0220] The negative electrode slurry is coated on the negative electrode current collector, dried and cold pressed to prepare the negative electrode sheet. The surface density of the negative electrode active layer is 64g / m 2±1g / m 2 , compacted density is 1.5g / cm 3 ±0.1g / cm 3 , and during the process of coating the negative electrode slurry on each negative electrode current collector, the negative electrode current collector did not break, and during the subsequent sheet pressing process, the electrode sheets only slightly warped or twisted. In addition, it should be noted that the numbering sequence of the negative electrode sheets corresponds to the numbering sequence of the negative electrode collectors. For example, negative electrode collector No. 1 is used to prepare negative electrode sheet No. 1, negative electrode collector No. 2 is used to prepare negative electrode sheet No. 2, and so on, and negative electrode collector No. 13 is used to prepare negative electrode sheet No. 13.

[0221] Example 3

[0222] Example 3 provides Figure 5 The lithium battery 1 shown includes the laminated No. 1 to No. 13 composite copper foil negative electrode sheets 10, separator 20, and positive electrode sheet 30 shown in Example 2, and another lithium battery 1', which differs from the lithium battery 1 in that the No. 14 pure copper foil negative electrode sheet shown in Example 2 is used to replace the negative electrode sheet 10, as follows:

[0223] (1) Negative electrode sheets: negative electrode sheets No. 1 to No. 14 shown in Example 2 were used respectively.

[0224] (2) Diaphragm: Use commercially available PP-PE-PP composite diaphragm.

[0225] (3) Positive electrode: A commercially available ternary nickel-cobalt-manganese positive electrode is used. The positive electrode current collector is aluminum foil, and the positive electrode active layer is made of nickel-cobalt-manganese ternary material, conductive carbon black and PVDF. The surface density is 115g / m 2 ±2g / m 2 , compacted density is 3.1g / cm 3 ±0.1g / cm 3 .

[0226] (4) Electrolyte: A commercially available ternary battery electrolyte was used, wherein the electrolyte salt was lithium hexafluorophosphate, the solvent was a mixed solvent of ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate, and the concentration of the electrolyte salt was 1.0 mol / L to 1.2 mol / L.

[0227] (5) Assemble the negative electrode sheet, separator and positive electrode sheet, weld the tabs, use aluminum plastic film as the outer shell, inject the battery electrolyte, and form the battery to prepare soft pack batteries. Each battery is an ultra-thin battery. The thickness of each lithium battery measured by the GH-D electronic thickness gauge is within the range of 0.5mm to 1mm. The battery performance test results are shown in Table 5 below, where the numbering sequence of the soft pack batteries corresponds to the numbering sequence of the negative electrode sheets. For example, the No. 1 negative electrode sheet is used to prepare the No. 1 soft pack battery, the No. 2 negative electrode sheet is used to prepare the No. 2 soft pack battery... and so on. The No. 13 negative electrode sheet is used to prepare the No. 13 soft pack battery.

[0228] Table 5 Performance results of soft pack batteries

[0229]

[0230] As can be seen from Table 5, compared with pure copper foil, the composite copper foil negative electrode current collector of the present application has the advantages of both ultra-thin copper foil and polymer substrate, and is lighter and thinner. By combining the lightweight negative electrode current collector with the negative electrode active layer arranged on its single-side surface, the weight and thickness of the negative electrode sheet can be significantly reduced, thereby reducing the weight and thickness of the battery, improving the energy density of the battery, and the capacity retention rate is comparable, and some embodiments are even higher than pure copper foil.

[0231] Figures 6 to 8 The discharge curves of the No. 10 lithium battery (composite copper foil as current collector) and the No. 14 lithium battery (pure copper foil as negative electrode current collector) shown in Example 3 of this application are respectively discharged at 0.2C, 0.5C and 1C currents. Figures 6 to 8 It can be seen that the resistance of the composite copper foil is higher than that of the pure copper foil. The lithium battery made with the composite copper foil as the negative electrode current collector has a larger internal resistance, a slightly lower discharge voltage than the battery made with pure copper foil as the negative electrode current collector, and a higher specific capacity.

[0232] In summary, compared with pure copper foil, the present application compounds ultra-thin copper foil and polymer substrate to prepare a composite copper foil negative electrode collector that is lighter and thinner. It can be used for battery negative electrode plates to prepare ultra-thin batteries, and can improve the energy density and specific capacity of the battery, and has good rate performance and broad application prospects.

[0233] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0234] The embodiments described above only express several implementation methods of the present application, which are convenient for understanding the technical solutions of the present application in a specific and detailed manner, but they cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all fall within the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description and drawings can be used to interpret the content of the claims.

Claims

1. A negative electrode plate, characterized in that: The negative electrode current collector comprises a negative electrode current collector and a negative electrode active layer arranged on a single side surface of the negative electrode current collector, wherein the negative electrode current collector comprises a polymer substrate layer, an adhesive layer and an ultra-thin copper foil stacked in sequence, wherein the thickness of the ultra-thin copper foil is 0.8μm to 4.5μm; the tensile strength of the negative electrode current collector is ≥180Mpa, and the elongation at break is ≥5%.

2. The negative electrode sheet according to claim 1, characterized in that: The ultra-thin copper foil is prepared by electrolysis, and the electroplating solution used in the electrolysis comprises a mother solution and an additive, wherein the additive comprises a combination of one or more of protein and hydroxyethyl cellulose.

3. The negative electrode sheet according to claim 2, characterized in that: Satisfy one or more of the following (1) to (2): (1) Based on the concentration in the electroplating solution, the additive includes: 20 ppm to 60 ppm of a protein component, wherein the protein component includes proteins of different molecular weights, the molecular weights of the proteins of different molecular weights are gradually distributed within the range of [molecular weight Min, molecular weight Max], and the proportions of the proteins of different molecular weights are uniform; (2) Based on the concentration in the electroplating solution, the additive includes: 20 ppm to 60 ppm of a hydroxyethyl cellulose mixture, wherein the hydroxyethyl cellulose mixture includes hydroxyethyl cellulose of different viscosities.

4. The negative electrode sheet according to claim 3, characterized in that: Satisfy one or more of the following (1) to (3): (1) Molecular weight Min ≥ 180, molecular weight Max ≤ 10000; (2) the viscosity of each hydroxyethyl cellulose is independently 15000 mPa·s to 100000 mPa·s; (3) The mother liquor comprises: With 2+ 65g / L~90g / L; H2SO4 75g / L~100g / L; Cl - 20ppm~30ppm。 5. The negative electrode sheet according to any one of claims 1 to 4, characterized in that: Satisfy one or more of the following (1) to (7): (1) The thickness of the polymer substrate layer is 1 μm to 6 μm; (2) The thickness of the adhesive layer is 0.2 μm to 4 μm; (3) The curing shrinkage of the adhesive layer is ≤3%; (4) The bonding force between the adhesive layer and the polymer substrate layer is 3N / 25mm to 30N / 25mm; (5) The bonding force between the adhesive layer and the ultra-thin copper foil is 3N / 25mm to 30N / 25mm; (6) The material of the polymer substrate layer is one or more of polyethylene terephthalate, polyethylene, polypropylene, polyimide, polyamide, polyester, polyvinyl chloride, polystyrene, polytetrafluoroethylene, polyvinylidene fluoride, polybutylene terephthalate, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene terpolymer, polyarylsulfone, polyethylene naphthalate, poly-3,4-ethylenedioxythiophene, polyaniline and polypyrrole; (7) The adhesive layer is formed by curing an adhesive liquid, and the adhesive liquid comprises a component A and a component B; wherein the component A comprises a combination of one or more of polyurethane resin, acrylic resin, epoxy resin, polyester resin, polyimide, silicone polymer and modified compounds thereof; the component B comprises a combination of one or more of amino resin, isocyanate, aziridine crosslinking agent, carbodiimide, silane coupling agent and silicone tackifier; the weight ratio of the component A to the component B is (90-99): (1-5).

6. The negative electrode sheet according to any one of claims 1 to 4, characterized in that: The negative electrode active layer satisfies one or more of the following (1) to (2): (1) The surface density of the negative electrode active layer is 25 g / m 2 ~200g / m 2 ; (2) The compaction density of the negative electrode active layer is 0.8 g / cm 3 ~2.0g / cm 3 .

7. A battery, characterized in that: The invention comprises a positive electrode sheet, a separator and the negative electrode sheet according to any one of claims 1 to 6.

8. The battery according to claim 7, characterized in that The positive electrode sheet includes a positive electrode current collector and a positive electrode active layer provided on a single side surface of the positive electrode current collector, wherein the positive electrode active layer satisfies one or more of the following (1) to (2): (1) The surface density of the positive electrode active layer is 50 g / m 2 ~350g / m 2 ; (2) The compaction density of the positive electrode active layer is 2.0 g / cm 3 ~4.0g / cm 3 .

9. The battery according to claim 7 or 8, characterized in that The battery is an ultra-thin battery.

10. An electrical device, characterized in that: The battery comprises the battery according to any one of claims 7 to 9, wherein the battery provides electrical energy for the electrical device.

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