Composite current collector, electrode assembly, method for manufacturing the same, and secondary battery

Abstract

The present application provides a composite current collector, which includes an organic support layer having an air permeability of 50s / 100mL or more and a conductive layer disposed on one surface of the organic support layer, so that the organic support layer can also function as a separator, thereby increasing the volumetric energy density of a secondary battery using the composite current collector.

Description

Technical Field

[0001] This application relates to the field of electrochemistry, and particularly to a composite current collector, a method for manufacturing the same, a secondary battery including the same, and a power consumption device.

Background Art

[0002] In recent years, with the increasingly wide application range of lithium-ion batteries, lithium-ion batteries have been widely applied in multiple fields such as energy storage power systems such as hydraulic power, thermal power, wind power, and solar power plants, and electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. Due to the remarkable development of lithium-ion batteries, higher requirements are also demanded for their energy density, cycle performance, safety performance, etc.

[0003] The electrode plate of the prior art includes a metal current collector and an active material layer formed on two surfaces of the current collector. And electrode plates with different polarities are separated from each other by a separator. Such an electrode plate structure requires the separator to be wound or laminated in two layers during manufacturing, and its manufacturing process is complicated. And in a secondary battery using such an electrode plate structure, its ion passage is long, which affects the charge and discharge characteristics.

Summary of the Invention

[0004] This application is made in view of the above problems, and its purpose is to provide a composite current collector, a method for manufacturing the same, a secondary battery including the same, and a power consumption device. The composite current collector can omit the separator installed between the electrode plates, simplify the manufacturing process, shorten the ion passage, and improve the charge and discharge characteristics. And since the space for installing the separator can be saved, more active material can be applied per unit volume, thus improving the energy density.

[0005] To achieve the above object, a first aspect of the present application provides a composite current collector, which includes an organic support layer having an air permeability of 50 s / 100 mL or more and a conductive layer disposed on one surface of the organic support layer.

[0006] By using an organic layer with an air permeability of 50 s / 100 mL or more as the support layer of the composite current collector, the support layer can be used as a separator, thereby omitting the separator installed between the electrode plates, simplifying the manufacturing process, shortening the ion passage, and improving the charge and discharge characteristics. And since the space for installing the separator can be saved, more active material can be applied per unit volume, thus improving the energy density.

[0007] In some embodiments, the air permeability of the organic support layer is 50 s / 100 mL to 2000 s / 100 mL, and optionally 100 s / 100 mL to 500 s / 100 mL. By controlling the air permeability of the organic support layer within the above range, the ion permeability can be ensured and the wettability of the electrolyte can be improved, and the lithium ions in the electrolyte can pass through smoothly. If the air permeability is too low, the separator pores correspond to closed pores, and the lithium ions in the electrolyte cannot pass through the separator, and high ion conduction performance cannot be realized. If the air permeability is too high, it corresponds to penetration, and large particle ions of other substances also permeate, and the performance as a separator is lost. Thereby, by reasonably setting the air permeability, the charge and discharge characteristics of the secondary battery can be further improved.

[0008] In some embodiments, the conductive layer has voids, and the porosity of the conductive layer is 10% to 95%, optionally 10% to 50%. By controlling the porosity of the conductive layer within the above range, a desired ionic conductivity can be satisfied, and the charge and discharge characteristics of the secondary battery can be further improved. When the porosity is within an appropriate range, it is possible to avoid insufficient ionic conductivity, while avoiding the situation where ions penetrate into the conductive layer but there is no extra space for excess ions to permeate through the organic support layer. In addition, the upper limit of the fiber void air permeability of the organic support layer has a positive correlation with the upper limit porosity of the conductive layer, and the ion permeability can be ensured.

[0009] In some embodiments, the organic support layer is a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof. By manufacturing the organic support layer using the above materials, a support layer with high ion permeability can be reliably formed.

[0010] In some embodiments, the thickness of the conductive layer is 200 nm to 3000 nm, optionally 500 nm to 1500 nm. By setting the thickness of the conductive layer within the above range, it is advantageous for improving the volume energy density of the secondary battery. When an abnormality such as a nail puncture occurs in the secondary battery, the burrs generated in the conductive layer are significantly reduced, the short-circuit resistance of the secondary battery is increased, the short-circuit current is decreased, and the short-circuit heat generation is decreased, thereby improving the safety performance of the secondary battery. On the other hand, it is advantageous for the composite current collector to have good electrical conductivity and current collection performance, and it is difficult for damage to occur during the processing and use of the composite current collector, so that the composite current collector has good mechanical stability and a long service life.

[0011] In some embodiments, the conductive layer includes a pore-forming transition layer, a build-up layer, a functional layer, and a protective layer laminated in order from the organic support layer. Thereby, an ion passage can be favorably formed in the conductive layer and the thickness of the conductive layer can be easily adjusted. Further, the protective layer can prevent the occurrence of damage such as chemical corrosion or mechanical destruction in the conductive layer, and ensure the high operating stability and long service life of the composite current collector. In addition, the protective layer can further enhance the mechanical strength of the composite current collector.

[0012] In some embodiments, the materials of the pore-forming transition layer, the build-up layer, and the functional layer are one or more of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, iron, iron alloy, silver, and silver alloy. The protective layer includes one or more of a metal, a metal oxide, and a conductive carbon, preferably one or more of nickel, chromium, nickel-based alloy, copper-based alloy, alumina, cobalt oxide, chromium oxide, nickel oxide, graphite, superconducting carbon, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber. Thereby, the protective layer can play a role in protecting the conductive layer against chemical corrosion and mechanical destruction, further improve the interface between the composite current collector and the active material layer, enhance the bonding force between the composite current collector and the positive electrode active material layer, and improve the performance of the secondary battery.

[0013] In some embodiments, the thickness of the pore-forming transition layer is 2 nm to 100 nm, optionally 10 nm to 50 nm; the thickness of the build-up layer is 5 nm to 300 nm, optionally 20 nm to 100 nm; and the thickness of the functional layer is 500 nm to 5000 nm, optionally 500 nm to 2000 nm. Thereby, the ion conduction performance, the electrical conductivity, and the mechanical stability of the composite current collector can be made compatible.

[0014] A primer layer containing an adhesive and a conductive agent is further provided between the active material layer and the conductive layer. The primer layer can improve the interface of the composite current collector, and can well overcome the defects of the composite current collector such as low conductivity, low overcurrent tolerance, and easy breakage of the conductive layer in the composite current collector, effectively repair the surface of the current collector, and construct a conductive network between the current collector, the conductive primer layer and the active material, so as to improve the electron transport efficiency, reduce the resistance between the current collector and the electrode active material layer, effectively reduce the DC internal resistance of the secondary battery, improve the output performance of the secondary battery, and ensure that phenomena such as large polarization and lithium precipitation do not easily occur in the battery cell during long-term cycling, that is, effectively improve the long-term reliability of the secondary battery.

[0015] The second aspect of the present application provides an electrode assembly, which includes a first electrode plate and a second electrode plate. One of the first electrode plate and the second electrode plate includes the composite current collector of the first aspect of the present application. An active material layer is provided on the conductive layer of the composite current collector, and the organic support layer of one of the first electrode plate and the second electrode plate and the active material layer of the other of the first electrode plate and the second electrode plate are installed to be in close contact. Thereby, the electrode plate including the composite current collector of the first aspect of the present application can be used in admixture with a general electrode plate having the opposite polarity, and the use of the separator can be further reduced.

[0016] The third aspect of the present application provides an electrode assembly, which includes a first electrode plate and a second electrode plate each including the composite current collector of the first aspect of the present application. An active material layer is provided on the conductive layer of the composite current collector, and the organic support layer of the first electrode plate and the active material layer of the second electrode plate are installed to be in close contact, and the organic support layer of the second electrode plate and the active material layer of the first electrode plate are installed to be in close contact. Thereby, by using electrode plates including the composite current collectors of the first aspect of the present application with different polarities, a secondary battery can be formed without installing a separator.

[0017] A fourth aspect of the present application provides a method for manufacturing a composite current collector described in the first aspect of the present application, the method including the following steps (1) to (3): Step (1): forming an organic support layer having an air permeability of 50 s / 100 mL or more; Step (2): forming a pore-forming transition layer on one surface of the organic support layer by a vapor growth method using a mask with voids; Step (3): electroplating a conductive metal layer on the pore-forming transition layer to form it.

[0018] By the above method, by using a mask to form voids in the conductive metal layer, high ion conduction performance can be formed, and the charge and discharge characteristics of the secondary battery can be further improved. Note that the pore-forming transition layer can easily form a porous electroplated layer as a base for the electroplated layer, and the thickness of the conductive metal layer can be easily adjusted by electroplating.

[0019] In some embodiments, further, it includes step (4) of forming a protective layer on the conductive metal layer.

[0020] Thereby, the protective layer can prevent the occurrence of damage such as chemical corrosion or mechanical destruction in the conductive layer, and ensure high operating stability and long service life of the composite current collector. Note that the protective layer can further increase the mechanical strength of the composite current collector.

[0021] In some embodiments, in step (2), the size and porosity of the voids in the pore-forming transition layer are adjusted according to the size and density of the voids in the mask. Thereby, the ion conduction performance and the conductive performance of the composite current collector can be made compatible.

[0022] In some embodiments, in the step (2), in a vacuum plating chamber, a conductive material is evaporated at a temperature of 1300°C to 2000°C, cooled, and deposited on the organic support layer to form the pore-forming transition layer. Thereby, the bonding force between the conductive metal layer and the organic support layer can be improved, and the supporting role of the organic support layer for the conductive metal layer can be effectively exerted.

[0023] In some embodiments, in the step (4), the protective layer is formed on the conductive metal layer by at least one of a vapor growth method, an in-situ formation method, or a coating method. Thereby, it is advantageous for improving the bonding force between the conductive layer and the protective layer, so that the protective role of the protective layer for the composite current collector can be better exerted, and the high operating performance of the composite current collector can be ensured.

[0024] The fifth aspect of the present application provides a method for manufacturing an electrode assembly, and the method includes: preparing a first electrode plate including a first composite current collector, wherein the first composite current collector is the composite current collector of the first aspect of the present application, and an active material layer is provided on the conductive layer of the composite current collector; preparing a second electrode plate including a second current collector and active material layers provided on two surfaces of the second current collector; preparing a separator; stacking the first electrode plate, the second electrode plate, and the separator in sequence such that the organic support layer of the first composite current collector of the first electrode plate contacts one of the active material layers of the second electrode plate, and the other active material layer of the second electrode plate contacts the separator, to obtain a stacked structure, and winding the stacked structure.

[0025] Thereby, the use of one layer of separator for manufacturing the electrode assembly can be reduced.

[0026] The sixth aspect of the present application provides a method for manufacturing an electrode assembly, and the method includes: To prepare a first electrode plate including a first current collector composite and a second electrode plate including a second current collector composite, wherein the first current collector composite and the second current collector composite are each the current collector composite of the first aspect of the present application, and an active material layer is provided on the conductive layer of the current collector composite. Winding the first electrode plate and the second electrode plate such that the organic support layer of the first current collector composite of the first electrode plate contacts the active material layer of the second electrode plate, and the organic support layer of the second current collector composite of the second electrode plate contacts the active material layer of the first electrode plate.

[0027] Thereby, an electrode assembly can be manufactured without a separator.

[0028] The seventh aspect of the present application provides a secondary battery, which includes at least one of the electrode assemblies described in the second and third aspects of the present application and the electrode assemblies manufactured by the manufacturing method described in the fifth and sixth aspects of the present application.

[0029] The eighth aspect of the present application provides a power consumption device, which includes the secondary battery described in the seventh aspect of the present application.

[0030] According to the present application, it is possible to achieve both the cycle performance, rate performance and low internal resistance of the secondary battery.

Brief Description of the Drawings

[0031]

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Embodiments for Carrying Out the Invention

[0032] The following will specifically disclose embodiments of the positive electrode material and its manufacturing method, secondary battery, battery module, battery pack, and power consumption device of the present application in detail with appropriate reference to the drawings. However, detailed descriptions that are not necessary may be omitted. For example, detailed descriptions of well-known matters and duplicate descriptions of structures that are actually the same may be omitted. This is to avoid making the following description unnecessarily long and to enable those skilled in the art to easily understand. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not for limiting the subject matter described in the claims.

[0033] The "range" disclosed in this application is limited in the form of a lower limit and an upper limit. A given range is limited by selecting one lower limit and one upper limit that define the boundaries of the specific range. The range thus defined may or may not include the end values and may be arbitrarily combined, that is, any lower limit and any upper limit may be combined to form one range. For example, if ranges of 60 to 120 and 80 to 110 are given for a specific parameter, ranges of 60 to 110 and 80 to 120 are also understood to be contemplated. Note that if minimum range values 1 and 2, and maximum range values 3, 4, and 5 are listed, the following ranges of 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 are all expected. In this application, unless otherwise stated, the numerical range "a to b" is a shorthand representation of all combinations of real numbers between a and b, where both a and b are real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" are listed in this specification, and "0 to 5" is merely an abbreviated representation of these numerical combinations. Also, when it is described that a certain parameter is an integer ≧ 2, this is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0034] Unless otherwise specifically described, all embodiments and selectable embodiments of this application may be combined with each other to form a new technical solution.

[0035] Unless otherwise specifically described, all technical features and selectable technical features of this application may be combined with each other to form a new technical solution.

[0036] Unless otherwise specifically described, the "comprising" and "including" mentioned in this application represent an open type and may also be a closed type. For example, the above "comprising" and "including" may further comprise or include other components not listed, or may represent comprising or including only the listed components.

[0037] Unless otherwise specified, in this application, the term "or" is inclusive. For example, the phrase "A or B" represents "A, B, or both A and B". More specifically, any one of the following conditions satisfies the condition of "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), or both A and B are true (or exist).

[0038] In one embodiment of the present application, a composite current collector is provided, which includes an organic support layer with an air permeability of 50 s / 100 mL or more, and a conductive layer disposed on one surface of the organic support layer.

[0039] The applicant of the present application has discovered the following. That is, by using an organic layer with an air permeability of 50 s / 100 mL or more as the support layer of the composite current collector, the support layer can be used as a separator, thereby omitting the separator installed between the electrode plates, simplifying the manufacturing process, shortening the ion passage, and improving the charge and discharge characteristics. And since the space for installing the separator can be saved, more active material can be applied per unit volume, thus improving the energy density.

[0040] In addition, the following will describe the composite current collector, secondary battery, and power consumption device of the present application with appropriate reference to the drawings.

[0041] [Composite Current Collector] FIG. 1 is a schematic cross-sectional view of a composite current collector according to an embodiment of the present application. As shown in FIG. 1, the composite current collector 610 includes an organic support layer 611 with an air permeability of 50 s / 100 mL or more, and a conductive layer 612 on one surface of the organic support layer 611 where the active material layer 62 is disposed.

[0042] In some embodiments, optionally, the air permeability of the organic support layer 611 is 50 s / 100 mL to 2000 s / 100 mL, and optionally 100 s / 100 mL to 500 s / 100 mL. By controlling the air permeability of the organic support layer within the above range, the ion permeability can be ensured and the wettability of the electrolyte can be improved, and the lithium ions in the electrolyte can pass smoothly. If the air permeability is too low, the separator voids correspond to closed pores, and the lithium ions in the electrolyte cannot pass through the separator, and high ion conduction performance cannot be realized. If the air permeability is too high, it corresponds to penetration, and large particle ions of other substances also permeate, and the performance as a separator is lost. Therefore, by reasonably setting the air permeability, the charge and discharge characteristics of the secondary battery can be further improved.

[0043] In some embodiments, optionally, the conductive layer 612 has voids, and the porosity of the conductive layer 612 is 10% to 95%, and optionally 10% to 50%. By controlling the porosity of the conductive layer 612 within the above range, the desired ion conductivity can be satisfied and the charge and discharge characteristics of the secondary battery can be further improved. By having the porosity within an appropriate range, it is possible to avoid insufficient ion conductivity, while at the same time avoiding the situation where ions penetrate into the conductive layer but there is no extra space for excess ions to permeate through the organic support layer 611. Note that the upper limit of the fiber void air permeability of the organic support layer 611 has a positive correlation with the upper limit porosity of the conductive layer, and the ion permeability can be ensured.

[0044] In some embodiments, in order to improve the electrolyte infiltration rate and allow ions to pass through quickly, the average pore diameter of the conductive layer 612 may be set to 100 nm to 1000 nm.

[0045] In some embodiments, optionally, the organic support layer 611 is a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof. By manufacturing the organic support layer using the above materials, a support layer with high ion permeability can be reliably formed.

[0046] In some embodiments, optionally, the thickness of the organic support layer 611 is, for example, 1000 to 8000 nm. Thereby, sufficient support strength can be provided.

[0047] In some embodiments, optionally, when the air permeability is 50 s / 100 mL to 2000 s / 100 mL, the material of the organic support layer may be one or more of polyamide (PA), polyimide (PI), polyester-based, polyolefin-based, polyalkyne-based, siloxane polymer, polyether-based, polyalcohol-based, polysulfone-based, polysaccharide-based polymer, amino acid-based polymer, polythiazyl-based, aromatic ring polymer, heteroaromatic ring polymer, epoxy resin, phenolic resin, their derivatives, their crosslinked products, and their copolymers. Further, the material of the organic support layer is, for example, polycaprolactam (commonly known as nylon 6), polyhexamethylene adipamide (commonly known as nylon 66), polyparaphenylene terephthalamide (PPTA), polymetaphenylene isophthalamide (PMIA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polycarbonate (PC), polyethylene (PE), polypropylene (PP), polypropylene ethylene (PPE), polyvinyl alcohol (PVA), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTEE), sodium polystyrene sulfonate (PSS), polyacetylene, polypyrrole (PPy), polyaniline (PAN), polythiophene (PT), polypyridine (PPY), silicone rubber, polyoxymethylene (POM), polyphenyl, polyphenylene oxide (PPO), polyphenylene sulfide (PPS), polyethylene glycol (PEG), acrylonitrile-butadiene-styrene copolymer (ABS), cellulose, starch, protein, their derivatives, their crosslinked products, and their copolymers.

[0048] In some embodiments, optionally, the thickness of the conductive layer 612 is from 200 nm to 3000 nm, and optionally from 500 nm to 1500 nm. When the thickness of the conductive layer is within the above range, it is advantageous for improving the volume energy density of the secondary battery. When an abnormality such as a nail puncture occurs in the secondary battery, the burrs generated in the conductive layer are significantly reduced, the short-circuit resistance of the secondary battery is increased, the short-circuit current is decreased, and the short-circuit heat generation is decreased, thereby improving the safety performance of the secondary battery. On the other hand, it is advantageous for the composite current collector to have good electrical conductivity and current collection performance, and it is difficult for damage to occur during the processing and use of the composite current collector. Thereby, the composite current collector has good mechanical stability and a long service life.

[0049] In some embodiments, optionally, as shown in FIG. 2, the conductive layer 612 includes a pore-forming transition layer 6121, a build-up layer 6122, a functional layer 6123, and a protective layer 6124 that are sequentially laminated from the organic support layer 611. Thereby, an ion passage can be well formed in the conductive layer 612 and the thickness of the conductive layer 612 can be easily adjusted. In addition, the protective layer 6124 can prevent the occurrence of damage such as chemical corrosion or mechanical destruction in the conductive layer 612, and can ensure the high operating stability and long service life of the composite current collector 610. Note that the protective layer 6124 can further increase the mechanical strength of the composite current collector 610.

[0050] In some embodiments, optionally, the materials of the pore-forming transition layer 6121, the build-up layer 6122, and the functional layer 6123 are one or more of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, iron, iron alloy, silver, and silver alloy. The protective layer 6124 is one or more of a metal, a metal oxide, and a conductive carbon, preferably one or more of nickel, chromium, nickel-based alloy, copper-based alloy, alumina, cobalt oxide, chromium oxide, nickel oxide, graphite, superconducting carbon, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber. Thereby, the protective layer 6124 can play a protective role in preventing chemical corrosion and mechanical damage to the conductive layer, further improving the interface between the composite current collector and the active material layer, enhancing the bonding force between the composite current collector and the positive electrode active material layer, and improving the performance of the secondary battery.

[0051] In some embodiments, optionally, the thickness of the pore-forming transition layer 6121 is 2 nm to 100 nm, optionally 10 nm to 50 nm, the thickness of the build-up layer 6122 is 5 nm to 300 nm, optionally 20 nm to 100 nm, and the thickness of the functional layer 6123 is 500 nm to 5000 nm, optionally 500 nm to 2000 nm. Thereby, the ion conduction performance, the electrical conductivity, and the mechanical stability of the composite current collector 610 can be made compatible.

[0052] In some embodiments, optionally, the thickness of the protective layer 6124 is 20 nm to 100 nm. Thereby, oxidation of the conductive layer can be prevented.

[0053] In some embodiments, optionally, as shown in FIG. 3, an undercoat layer 64 containing an adhesive and a conductive agent is further provided between the active material layer 62 and the conductive layer 612. The undercoat layer 64 can improve the interface of the composite current collector 610, and can well overcome the defects of the composite current collector such as low conductivity, low overcurrent tolerance, and easy breakage of the conductive layer in the composite current collector. By effectively repairing the surface of the current collector and constructing a conductive network between the current collector, the conductive undercoat layer and the active material, the electron transport efficiency is improved, the resistance between the current collector and the electrode active material layer is reduced, thereby effectively reducing the DC internal resistance of the secondary battery, improving the output performance of the secondary battery, and ensuring that phenomena such as large polarization and lithium precipitation do not easily occur in the battery cell during long-term cycling, that is, effectively improving the long-term reliability of the secondary battery.

[0054] Obviously, the composite current collector in the present application may be used for the positive electrode plate or the negative electrode plate. When used for the positive electrode plate, accordingly, the composite current collector and the active material layer are the positive current collector and the positive electrode active material layer, respectively. When used for the negative electrode plate, accordingly, the composite current collector and the active material layer are the negative current collector and the negative electrode active material layer, respectively.

[0055] When the composite current collector 610 of the present application is the positive current collector, the positive electrode plate includes the positive composite current collector and a positive electrode active material layer provided on one surface of the positive current collector. The positive electrode active material layer contains a positive electrode active material.

[0056] In some embodiments, the positive electrode active material may employ a positive electrode active material for batteries well-known in the art. As an example, the positive electrode active material may include at least one material among olivine-structured lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, in this application, it is not limited to these materials, and other conventional materials that can be used as the positive electrode active material of the battery may also be used. These positive electrode active materials may be used alone or in combination of two or more. Here, examples of lithium transition metal oxides are lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which may also be abbreviated as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which may also be abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which may also be abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which may also be abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which may also be abbreviated as NCM811), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05It may contain, but is not limited to, at least one of O2) and its modified compounds. Examples of lithium-containing phosphates with an olivine structure include lithium iron phosphate (e.g., LiFePO4 (which may also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon, but are not limited thereto.

[0057] In some embodiments, the positive electrode active material layer may optionally further contain an adhesive. As an example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0058] In some embodiments, the positive electrode active material layer may optionally further contain a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0059] In some embodiments, the positive electrode plate can be manufactured in the following manner. The above components for manufacturing the positive electrode plate, such as the positive electrode active material, the conductive agent, the adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry. The positive electrode slurry is applied to the positive electrode current collector composite, and after processes such as drying and cold pressing, a positive electrode plate is obtained.

[0060] When the current collector 610 of the present application is a negative electrode current collector, the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer disposed on one surface of the negative electrode current collector. The negative electrode active material layer contains a negative electrode active material.

[0061] In some embodiments, the negative electrode active material may employ a negative electrode active material for batteries well-known in the art. As an example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of silicon alone, silicon oxide, silicon carbon composite, silicon nitride composite, and silicon alloy. The tin-based material may be selected from at least one of tin alone, tin oxide, and tin alloy. However, in the present application, it is not limited to these materials, and other conventional materials that can be used as the negative electrode active material of the battery may be used. These negative electrode active materials may be used alone or in combination of two or more.

[0062] In some embodiments, the negative electrode active material layer may optionally further include an adhesive. The adhesive may be selected from at least one 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).

[0063] In some embodiments, the negative electrode active material layer may optionally further include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0064] In some embodiments, the negative electrode active material layer optionally further contains other auxiliaries, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0065] In some embodiments, the negative electrode plate can be manufactured in the following manner. The above components for manufacturing the negative electrode plate, such as the negative electrode active material, the conductive agent, the adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry. The negative electrode slurry is applied to the negative electrode composite current collector, and after processes such as drying and cold pressing, a negative electrode plate is obtained.

[0066] [Method for manufacturing a composite current collector] In another embodiment of the present application, a method for manufacturing a composite current collector is provided, including the following steps (1) to (3): Step (1): Form an organic support layer with an air permeability of 50 s / 100 mL or more. Step (2): Using a mask with voids, form a pore-forming transition layer on one surface of the organic support layer by vapor phase growth method. Step (3): Electroplate a conductive metal layer on the pore-forming transition layer to form it.

[0067] By the above method, by using a mask to form voids in the conductive metal layer, high ion conduction performance can be formed, and the charge and discharge characteristics of the secondary battery can be further improved. In addition, the pore-forming transition layer can easily form a conductive metal layer with voids as a base for the electroplated layer, and the thickness of the conductive metal layer can be easily adjusted by electroplating.

[0068] In some embodiments, further, Step (4): Form a protective layer on the conductive metal layer.

[0069] Thereby, the protective layer can prevent the occurrence of damage such as chemical corrosion or mechanical destruction in the conductive layer, and ensure the high operating stability and long service life of the composite current collector. In addition, the protective layer can further increase the mechanical strength of the composite current collector.

[0070] In some embodiments, in the step (2), the size and porosity of the pore-forming transition layer are adjusted according to the size and density of the voids in the mask. Thereby, the ion conduction performance and the conductive performance of the composite current collector can be made compatible with each other.

[0071] In some embodiments, in the step (2), in a vacuum plating chamber, a conductive material is evaporated at a temperature of 1300°C to 2000°C, cooled, and deposited on the organic support layer to form the pore-forming transition layer. Thereby, the bonding force between the conductive metal layer and the organic support layer can be improved, and the supporting role of the organic support layer for the conductive metal layer can be effectively exerted.

[0072] In some embodiments, in the step (4), the protective layer is formed on the conductive metal layer by at least one of a vapor growth method, an in-situ formation method, or a coating method. Thereby, it is advantageous for improving the bonding force between the conductive layer and the protective layer, so that the protective role of the protective layer for the composite current collector can be better exerted, and the high operating performance of the composite current collector can be ensured.

[0073] In some embodiments, in the step (3), the build-up layer and the functional layer can be respectively formed by two electroplating processes. Thereby, conductive metal layers with different thicknesses can be easily formed.

[0074] [Electrode Assembly] In one embodiment of the present application, an electrode assembly is provided. The electrode assembly 52 includes a positive electrode plate (first electrode plate) 6, a negative electrode plate (second electrode plate) 7, and a separator 8 that plays a role in preventing short circuit between the positive and negative electrodes when manufacturing the electrode assembly in a winding process and allows ions to pass through. In this specification, the positive electrode plate is referred to as the first electrode plate, and the negative electrode plate is referred to as the second electrode plate, but it may also be reversed.

[0075] In some embodiments, the positive electrode plate among the positive electrode plate and the negative electrode plate is the electrode plate having the above structure of the present application. The negative electrode plate among the positive electrode plate and the negative electrode plate is an electrode plate having a conventional structure, but the reverse may also be true.

[0076] As shown in FIG. 4, the positive electrode plate 6 includes a composite current collector 610, an active material layer 62 disposed on one surface of the composite current collector 610, and an electrical connection member 63 electrically connected to the conductive layer 612 of the composite current collector 610.

[0077] The negative electrode plate 7 includes a negative electrode current collector 71, negative electrode active material layers 72 formed on two surfaces of the negative electrode current collector 71, and an electrical connection member 73 electrically connected to the negative electrode current collector 71. When viewed from the longitudinal direction X of the electrode plate, the organic support layer 611 of the positive electrode plate 6 is disposed so as to be in close contact with the negative electrode active material layer 72 of the negative electrode plate 7.

[0078] FIG. 5 is a plan view after winding of the electrode assembly 52 shown in FIG. 4. After the electrode assembly is wound, the positive electrode active material layer of the positive electrode plate 6 is in close contact with the separator 8, and the organic support layer of the positive electrode plate 6 is disposed so as to be in close contact with one negative electrode active material layer 72 of the negative electrode plate 7.

[0079] Thereby, it is not necessary to provide a separator between the positive electrode plate 6 and the negative electrode plate 7 of the present embodiment, and the organic support layer 611 acts as a separator between the positive electrode plate 6 and the negative electrode plate 7. The negative electrode plate 7 and the positive electrode plate 6 are separated by a separator 8.

[0080] FIG. 6 is a cross-sectional view of an electrode assembly 52A according to an embodiment of the present application. FIG. 7 is a plan view after winding of the electrode assembly 52A shown in FIG. 6. The difference between the electrode assembly 52A and the above-described electrode assembly 52 is that the positive electrode plate and the negative electrode plate are each an electrode plate having the above structure of the present application. That is, the negative electrode plate 6A includes a current collector 610A, an active material layer 62A disposed on one surface of the current collector 610A, and an electrical connection member 63A electrically connected to the current collector 610A.

[0081] As shown in FIGS. 6 and 7, in the present embodiment, the organic support layer 611 of the positive electrode plate 6 is installed so as to be in close contact with the negative electrode active material layer 62A of the negative electrode plate 6A, and the organic support layer 611A of the negative electrode plate 6A is installed so as to be in close contact with the positive electrode active material layer 62 of the positive electrode plate 6. Thereby, it is not necessary to install a separator between the positive and negative electrode plates 6 and 6A of the present embodiment, and the organic support layers 611 and 611A act as a separator between the positive and negative electrode plates 6 and 6A.

[0082] In addition, although the above embodiment has been described by taking the form of winding the electrode plates as an example, it is also applicable to laminated electrode plates.

[0083] [Method for manufacturing an electrode assembly] In another embodiment of the present application, a method for manufacturing an electrode assembly is provided, and the method includes: preparing a first electrode plate including a first current collector composite body, wherein the first current collector composite body is the current collector composite body of the first aspect of the present application; preparing a second electrode plate including a second current collector and active material layers installed on two surfaces of the second current collector; preparing a separator; stacking the first electrode plate, the second electrode plate, and the separator in this order such that the organic support layer of the first current collector composite body of the first electrode plate contacts one of the active material layers of the second electrode plate, and the other active material layer of the second electrode plate contacts the separator to obtain a stacked structure, and winding the stacked structure.

[0084] Thereby, the use of one layer of separator for manufacturing the electrode assembly can be reduced.

[0085] In another embodiment of the present application, a method for manufacturing an electrode assembly is provided, and the method includes: preparing a first electrode plate including a first current collector composite body and a second electrode plate including a second current collector composite body, wherein the first current collector composite body and the second current collector composite body are respectively the current collector composite bodies of the first aspect of the present application; Winding the first electrode plate and the second electrode plate such that the organic support layer of the first current collector of the first electrode plate contacts the active material layer of the second electrode plate and the organic support layer of the second current collector of the second electrode plate contacts the active material layer of the first electrode plate.

[0086] Thereby, a secondary battery can be manufactured without a separator.

[0087] [Secondary battery] In one embodiment of the present application, a secondary battery is provided. The secondary battery includes the composite current collector or the electrode assembly of the present application described above.

[0088] The secondary battery further includes an electrolyte. During the charge and discharge process of the battery, active ions reciprocate between the positive electrode plate and the negative electrode plate for intercalation and deintercalation. The electrolyte plays a role in conducting ions between the positive electrode plate and the negative electrode plate.

[0089] (Electrolyte) The electrolyte plays a role in conducting ions between the positive electrode plate and the negative electrode plate. The present application does not specifically limit the type of the electrolyte, and it can be selected according to the needs. For example, the electrolyte may be liquid, gel-like or all-solid.

[0090] In some embodiments, the electrolyte employs an electrolytic solution. The electrolytic solution includes an electrolyte salt and a solvent.

[0091] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate and lithium tetrafluoro(oxalato)phosphate.

[0092] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone.

[0093] In some embodiments, the electrolyte may optionally further contain an additive. For example, the additive may include a negative electrode film-forming additive and a positive electrode film-forming additive, or may further include an additive that can improve some performances of the battery, such as an additive that improves the overcharge performance of the battery, an additive that improves the high-temperature or low-temperature performance of the battery, and the like.

[0094] (Separator) In some embodiments, to play a role in preventing short circuit between the positive and negative electrodes and allowing ions to pass through, the secondary battery may further include a separator disposed between the positive electrode plate and the negative electrode plate. However, since the support layer in the electrode plate of the present application can also act as a separator, in the secondary battery of the present application, when the positive electrode plate and the negative electrode plate are separated by the support layer, it may not be necessary to separately provide a separator. In the present application, there is no particular limitation on the type of the separator, and any separator having a porous structure with well-known good chemical stability and mechanical stability may be selected.

[0095] In some embodiments, the material of the separator may be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer thin film or a multi-layer composite thin film, and there is no particular limitation. When the separator is a multi-layer composite thin film, the materials of each layer may be the same or different, and there is no particular limitation.

[0096] In some embodiments, the positive electrode plate, the negative electrode plate, and the separator installed as required may manufacture the electrode assembly by a winding process or a lamination process.

[0097] In some embodiments, the secondary battery may include an exterior. This exterior may be used for packaging the above electrode assembly and electrolyte.

[0098] In some embodiments, the exterior of the secondary battery may be a rigid shell such as a rigid plastic shell, an aluminum shell, or a steel shell. The exterior of the secondary battery may also be a soft bag, for example, a bag-type soft bag. The material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0099] In the present application, the shape of the secondary battery is not particularly limited, and it may be cylindrical, square, or any other shape. For example, FIG. 8 shows a secondary battery 5 having a square structure as an example.

[0100] In some embodiments, referring to FIG. 9, the exterior may include a housing 51 and a cover plate 53. Here, the housing 51 may include a bottom plate and side plates connected on the bottom plate, and the bottom plate and the side plates surround to form an accommodation cavity. The housing 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can close the accommodation cavity by being provided to cover the opening. The positive electrode plate, the negative electrode plate, and the separator installed as required can form an electrode assembly 52 by a winding process or a lamination process. The electrode assembly 52 is packaged in the accommodation cavity. The electrolyte infiltrates the electrode assembly 52. The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art may select according to actual specific needs.

[0101] In some embodiments, the secondary battery may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more. Specifically, those skilled in the art may select the number based on the application and capacity of the battery module.

[0102] [Battery Module] FIG. 10 shows a battery module 4 as an example. Referring to FIG. 10, in the battery module 4, a plurality of secondary batteries 5 may be arranged in sequence along the longitudinal direction of the battery module 4. Of course, they may be arranged according to any other method. Further, the plurality of secondary batteries 5 may be fixed with a fastener.

[0103] Optionally, the battery module 4 may further include a housing having an accommodation space for accommodating a plurality of secondary batteries 5.

[0104] In some embodiments, the above battery module may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more. Specifically, those skilled in the art may select the number based on the application and capacity of the battery pack.

[0105] [Battery Pack] FIGS. 11 and 12 show a battery pack 1 as an example. Referring to FIGS. 11 and 12, the battery pack 1 may include a battery case and a plurality of battery modules 4 installed in the battery case. The battery case includes an upper case 2 and a lower case 3. The upper case 2 is provided to cover the lower case 3 and can form a sealed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery case according to any method.

[0106] [Power Consumption Device] The present application further provides a power consumption device including at least one of a secondary battery, a battery module, or a battery pack according to the present application. The secondary battery, battery module, or battery pack may be used as a power source of the power consumption device or as an energy storage unit of the power consumption device. The power consumption device may include, but is not limited to, mobile equipment (such as mobile phones, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, and the like.

[0107] As the power consumption device, a secondary battery, a battery module, or a battery pack may be selected according to the demand in its use.

[0108] FIG. 13 shows a power consumption device as an example. This power consumption device is, for example, a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the requirements of high output and high energy density for the secondary battery, a battery pack or a battery module can be used.

[0109] Another example of the device may be a mobile phone, a tablet computer, a laptop computer, etc. This device is generally required to be lightweight and can employ a secondary battery as a power source.

[0110] Examples The manufacturing methods of the current collectors used in the electrode plates in each of the examples and comparative examples are as follows.

[0111] 1. Manufacturing of the composite current collector: A support layer with a thickness of 5000 nm and a certain air permeability (50 s / 100 mL or more) was selected, and a conductive layer with a certain thickness was formed on its surface by using a mask with voids by means such as vacuum evaporation or electroplating. The air permeability can be tested with reference to the standard GB / T 36363-2018.

[0112] Here, the formation conditions of the vacuum evaporation method are as follows. The surface-cleaned support layer is placed in the vacuum plating chamber, and high-purity metal wire in the metal evaporation chamber is melted and evaporated at a high temperature of 1300°C to 2000°C. After evaporation, the metal passes through the cooling system in the vacuum plating chamber and finally deposits on the surface of the support layer to form the conductive layer.

[0113] The formation conditions of the electroplating method are as follows.

[0114] (1) Current density: The current applied per unit electroplating area. Generally, the higher the current density, the thicker the film, but if it is too high, the plating layer will burn and become rough.

[0115] (2) Electroplating position: The position of the object to be plated in the plating solution or the position corresponding to the anode, which affects the distribution of the film thickness.

[0116] (3) Stirring condition: The better the stirring effect, the higher the electroplating efficiency. There are stirring methods such as air, water flow, and cathode.

[0117] (4) Current waveform: Generally, the higher the filtering degree, the more uniform the plating layer structure.

[0118] (5) Plating solution temperature: For gold plating, it is about 50 - 60°C, for nickel plating, it is about 50 - 60°C, for tin-lead plating, it is about 17 - 23°C, and for palladium-nickel plating, it is about 45 - 55°C.

[0119] (6) Plating solution pH value: For gold plating, it is about 4.0 - 4.8, for nickel plating, it is about 3.8 - 4.4, and for palladium-nickel plating, it is about 8.0 - 8.5.

[0120] (7) Plating solution specific gravity: Basically, the lower the specific gravity, the worse the chemical solution conductivity and the lower the electroplating efficiency.

[0121] 2. Manufacturing of the electrode plate: 1) Positive electrode plate without a conductive undercoat layer: 92 wt% of positive electrode active material (when no specific material is specified, NCM333 is used by default), 5 wt% of conductive agent Super-P (abbreviated as "SP"), and 3 wt% of PVDF are uniformly stirred with NMP as the solvent to form a positive electrode active material layer slurry (the composition of the active material layer slurry in some examples may vary, in which case the specific description in that example shall prevail). The slurry is applied by pressing and coating in a partitioned manner onto one surface of the composite current collector manufactured by the above method, and dried at 85 °C to obtain a positive electrode active material layer. Then, the current collector with each coating layer is cold-pressed and cut, and then dried under vacuum conditions at 85 °C for 4 hours, and tabs are welded to obtain a positive electrode plate.

[0122] 2) Conventional positive electrode plate: The current collector is an Al foil sheet with a thickness of 12 μm. Similar to the manufacturing method of the above positive electrode plate, the positive electrode active material layer slurry is directly applied to the surface of the Al foil sheet current collector, and then post-treated to obtain a conventional positive electrode plate.

[0123] 3) Positive electrode plate with a conductive undercoat layer: A conductive material (e.g., conductive carbon black) and an adhesive (e.g., PVDF or polyacrylic acid, etc.) and an optional active material in a certain mixing ratio (4:1) are dissolved in a suitable solvent (e.g., NMP or water), uniformly stirred, and blended into an undercoat slurry.

[0124] The undercoat slurry is uniformly applied to the surface of the conductive layer of the composite current collector, the coating speed is 20 m / min, and the undercoat layer is dried, with the oven temperature being 70 - 100 °C and the drying time being 5 min.

[0125] After the undercoat layer was completely dried, 92 wt% of the positive electrode active material, 5 wt% of the conductive agent Super-P (abbreviated as "SP"), and 3 wt% of PVDF were uniformly stirred with NMP as the solvent and compounded into the positive electrode active material layer slurry. Using extrusion coating, the positive electrode active material layer slurry was partitioned and coated on the surface of the undercoat layer, and after drying at 85 °C, a positive electrode active material layer was obtained. Next, post-treatment was performed to obtain a positive electrode plate having a conductive undercoat layer.

[0126] 4) Negative electrode plate having a conductive undercoat layer: Artificial graphite of the negative electrode active material, conductive agent Super-P, thickener CMC, and adhesive SBR were added to deionized water as the solvent in a mass ratio of 96.5:1.0:1.0:1.5 and uniformly mixed to obtain a negative electrode active material layer slurry. Using extrusion coating, the negative electrode active material layer slurry was partitioned and coated on one surface of the composite current collector manufactured by the above method, and after drying at 85 °C, a negative electrode active material layer was obtained.

[0127] Then, the current collector having each coating layer was cold-pressed and then cut, and then dried under vacuum conditions at 110 °C for 4 hours, and tabs were welded to obtain a negative electrode plate.

[0128] 5) Conventional negative electrode plate: The current collector is a Cu foil sheet with a thickness of 8 μm, which is similar to the manufacturing method of the above negative electrode plate. The negative electrode active material layer slurry was directly coated on the surface of the Cu foil sheet current collector, and then post-treatment was performed to obtain a conventional negative electrode plate.

[0129] 6) Negative electrode plate having a conductive undercoat layer: A conductive material (for example, conductive carbon black) and an adhesive (for example, PVDF or polyacrylic acid, etc.) and an optional active material in a certain mixing ratio (4:1) were dissolved in a suitable solvent (for example, NMP or water), and uniformly stirred and compounded into an undercoat slurry.

[0130] The undercoat slurry was uniformly coated on the surface of the conductive layer of the composite current collector, the coating speed was 20 m / min, and the undercoat layer was dried, the oven temperature was 70 - 100 °C, and the drying time was 5 min.

[0131] After the undercoat layer was completely dried, artificial graphite of the negative electrode active material, conductive agent Super-P, thickener CMC, and adhesive SBR were added to deionized water as the solvent at a mass ratio of 96.5:1.0:1.0:1.5, and uniformly mixed to obtain a negative electrode active material layer slurry. Using pressing coating, the negative electrode active material layer slurry was partitioned and coated on the undercoat layer of the current collector, dried at 85°C, and then a negative electrode active material layer was obtained. Next, post-treatment was performed to obtain a negative electrode plate having a conductive undercoat layer in the extending region.

[0132] 3. Battery manufacturing: According to the conventional battery manufacturing process, a positive electrode plate (compression density: 3.4 g / cm3), a negative electrode plate (compression density: 1.6 g / cm3), and a PP / PE / PP separator (select two separators, one separator, or no separator as required) were wound together to form a bare cell, then placed in a battery casing, and an electrolyte (EC:EMC volume ratio is 3:7, and LiPF6 is 1 mol / L) was injected. Next, processes such as sealing and formation were performed, and finally a lithium-ion secondary battery (hereinafter abbreviated as a battery) was obtained.

[0133] 4. Battery test method: 1) Rate performance test: Under the condition of 25±5°C, the battery was discharged at a constant current of 1.0 CmA until 3.0 V. After being fully charged, it was left standing for 2 hours. The appearance of the battery was visually inspected, and the size, open circuit voltage, and internal resistance of the battery were measured. After the test was completed, three 1.0 CmA cycles (discharge, full charge, discharge, full charge, discharge, 50% charge or full charge) were performed, and the discharge capacity of the third cycle was tested at the median voltage.

[0134] 2) Cycle performance test After the battery was fully charged under the condition that the ambient temperature was 25±5°C, it was left standing for 10 min, discharged at 10.0 CmA or the nominal rate current until 3.0 V, left standing for 10 min, and the above steps were repeated cyclically until the discharge capacity of the battery became the discharge capacity of the third cycle where the continuous two times ≤ 80%.

[0135] 3) Test method for DCR (direct current internal resistance): According to the physical formula R = V / I, the test equipment forced a large constant direct current (currently, generally a large current of 40A - 80A is used) to flow through the battery within a short time (generally 2 - 3 seconds), measured the voltage across the battery at this time, and calculated the current internal resistance of the battery based on the formula.

[0136] 5. Test Results and Discussions: 5.1 Influence of the Parameters of the Organic Support Layer on the Performance of the Secondary Battery Basically according to the parameters in Table 1 and Table 2 below, based on the composite current collectors 1 - 9 and Examples 1 - 7 and Comparative Examples 1 - 2 for manufacturing secondary batteries described in the above "1. Manufacturing of the Composite Current Collector", "2. Manufacturing of the Electrode Plate", and "3. Manufacturing of the Battery", tests were conducted.

Table 1

Table 2

[0137] As can be seen from the results in Tables 1 and 2, by comparing Examples 1 - 7 with Comparative Examples 1 - 2, it was found that by setting the air permeability of the organic support layer within the range of 50 - 2000 s / 100 mL, better rate characteristics and cycle characteristics can be obtained compared to Comparative Examples 1 and 2.

[0138] 5.2 Influence of the Parameters of the Conductive Layer on the Performance of the Secondary Battery Basically according to the parameters in Table 3 and Table 4 below, based on the composite current collectors 10 - 20 and Examples 8 - 18 and Comparative Example 3 for manufacturing secondary batteries described in the above "1. Manufacturing of the Composite Current Collector", "2. Manufacturing of the Electrode Plate", and "3. Manufacturing of the Battery", tests were conducted.

Table 3

Table 4

[0139] As can be seen from the results of Tables 3 and 4, by comparing Examples 8 to 11 with Examples 15 to 16, it was found that by setting the thickness of the conductive layer within the range of 200 to 3000 nm, the internal resistance of the secondary battery can be reduced, and excellent rate characteristics and cycle characteristics can be maintained.

[0140] As can be seen from the results of Tables 3 and 4, by comparing Examples 8, 12 to 14 with Examples 17 to 18, it was found that by setting the porosity of the conductive layer within the range of 10% to 95%, a low internal resistance of the secondary battery, and excellent rate characteristics and cycle characteristics can be maintained.

[0141] As can be seen from the results of Tables 3 and 4, by comparing Examples 8 to 18 with Comparative Example 3, it was found that the secondary battery having the composite current collector of the present application has a low internal resistance and excellent rate characteristics and cycle characteristics.

[0142] 5.3 Influence of the Structure of the Composite Current Collector on the Volume Energy Density of the Secondary Battery According to the parameters in Table 5 below, basically, based on Examples 3, 19 and Comparative Example 3 for manufacturing secondary batteries described in "1. Manufacture of the composite current collector", "2. Manufacture of the electrode plate" and "3. Manufacture of the battery" above, a volume energy density test was conducted.

Table 5

[0143] As can be seen from the results of Table 5, by comparing Examples 10 and 19 with Comparative Example 3, it was found that the secondary battery having the composite current collector of the present application has a high energy density. And from the comparison between Examples 10 and 19, it was found that the secondary battery in which both the positive and negative electrode plates have the composite current collector has a higher volume energy density.

[0144] 5.4 Influence of the Undercoat Layer on the Performance of the Secondary Battery Basically, according to the parameters in Table 6 below, a volume energy density test was conducted based on Example 3, Example 19, and Comparative Example 3 for manufacturing a secondary battery as described in "1. Manufacturing of the composite current collector", "2. Manufacturing of the electrode plate", and "3. Manufacturing of the battery".

Table 6

[0145] As can be seen from the results in Table 6, by comparing Example 10 with Examples 20 and 21, it was found that the secondary batteries of Examples 20 and 21 having an undercoat layer had lower internal resistance.

[0146] It should be noted that this application is not limited to the above embodiments. The above embodiments are merely examples, and within the scope of the technical solution of this application, embodiments having substantially the same configuration in terms of technical idea and exhibiting the same actions and effects are all included within the technical scope of this application. In addition, within the scope not departing from the gist of this application, various modifications that can be conceived by those skilled in the art can be implemented for the embodiments, and other forms constructed by combining some components in the embodiments are also included within the scope of this application.

Explanation of Reference Numerals

[0147] 1 Battery pack, 2 Upper case, 3 Lower case, 4 Battery module, 5 Secondary battery, 51 Housing, 52, 52A Electrode assembly, 53 Top cover assembly, 610, 610A Composite current collector, 611, 611A Organic support layer, 612, 612A Conductive layer, 62, 62A Active material layer, 6121 Pore-forming transition layer, 6122 Build-up layer, 6123 Functional layer, 6124 Protection layer, 63, 63A Electrical connection member, 64 Undercoat layer, 6, 6A, 7 Electrode plate, 71 Current collector, 72 Active material layer, 73 Electrical connection member, 8 Separator.

Claims

1. A composite current collector, comprising: an organic support layer having an air permeability of 50 s / 100 mL to 2000 s / 100 mL; and a conductive layer disposed on one surface of the organic support layer, wherein the conductive layer includes a pore-forming transition layer, a build-up layer, a functional layer, and a protective layer laminated in sequence from the organic support layer, wherein the materials of the pore-forming transition layer, the build-up layer, and the functional layer are one or more of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, iron, iron alloy, silver, and silver alloy; the protective layer includes one or more of a metal, a metal oxide, and a conductive carbon, the composite current collector.

2. The composite current collector according to claim 1, wherein the air permeability of the organic support layer is 100 s / 100 mL to 500 s / 100 mL.

3. The conductive layer has voids, The composite current collector according to claim 1 or 2, wherein the porosity of the conductive layer is 10% to 95%.

4. The composite current collector according to claim 3, wherein the porosity of the conductive layer is 10% to 50%.

5. The composite current collector according to any one of claims 1 to 4, wherein the organic support layer is a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof.

6. The composite current collector according to any one of claims 1 to 5, wherein the thickness of the conductive layer is 200 nm to 3000 nm.

7. The composite current collector according to claim 6, wherein the thickness of the conductive layer is 500 nm to 1500 nm.

8. The composite current collector according to claim 1, wherein the protective layer includes one or more of nickel, chromium, nickel-based alloy, copper-based alloy, alumina, cobalt oxide, chromium oxide, nickel oxide, graphite, superconducting carbon, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

9. The thickness of the pore-forming transition layer is 2 nm to 100 nm, the thickness of the build-up layer is 5 nm to 300 nm, the thickness of the functional layer is 500 nm to 5000 nm, the composite current collector according to claim 1.

10. The thickness of the pore-forming transition layer is 10 nm to 50 nm, and / or the thickness of the build-up layer is 20 nm to 100 nm, and / or the thickness of the functional layer is 500 nm to 2000 nm, the composite current collector according to claim 9.

11. The composite current collector according to any one of claims 1 to 10, wherein an undercoat layer containing an adhesive and a conductive agent is further provided between the active material layer and the conductive layer.

12. An electrode assembly, comprising a first electrode plate and a second electrode plate, wherein one of the first electrode plate and the second electrode plate includes the composite current collector according to any one of claims 1 to 11 and an active material layer provided on the conductive layer of the composite current collector, The electrode assembly, wherein the organic support layer of one of the first electrode plate and the second electrode plate and the active material layer of the other of the first electrode plate and the second electrode plate are arranged to be in close contact with each other.

13. An electrode assembly, comprising a first electrode plate and a second electrode plate, wherein the first electrode plate and the second electrode plate each include the composite current collector according to any one of claims 1 to 11 and an active material layer provided on the conductive layer of the composite current collector, wherein the organic support layer of the first electrode plate and the active material layer of the second electrode plate are arranged to be in close contact with each other, and The electrode assembly, wherein the organic support layer of the second electrode plate and the active material layer of the first electrode plate are arranged to be in close contact with each other.

14. A method for manufacturing a composite current collector, comprising: step (1) of forming an organic support layer having an air permeability of 50 s / 100 mL to 2000 s / 100 mL; step (2) of forming a pore-forming transition layer on one surface of the organic support layer by a vapor phase growth method using a mask with voids; step (3) of forming a build-up layer and a functional layer on the pore-forming transition layer by electroplating twice respectively; step (4) of forming a protective layer on the functional layer.

15. The method for manufacturing a composite current collector according to claim 14, wherein in step (2), the size and porosity of the voids in the pore-forming transition layer are adjusted according to the size and density of the voids in the mask.

16. The method for manufacturing a composite current collector according to claim 14, wherein in step (2), a conductive material is evaporated at a temperature of 1300 °C to 2000 °C in a vacuum plating chamber, cooled, and deposited on the organic support layer to form the pore-forming transition layer.

17. The method for manufacturing a composite current collector according to claim 14, wherein in step (4), the protective layer is formed on the functional layer by at least one of a vapor phase growth method, an in-situ formation method, or a coating method.

18. A method for manufacturing an electrode assembly, Preparing a first electrode plate including a first current collector composite, wherein the first current collector composite is the current collector composite according to any one of claims 1 to 11, and an active material layer is provided on the conductive layer of the current collector composite; Preparing a second electrode plate including a second current collector and active material layers provided on two surfaces of the second current collector; Preparing a single separator; Stacking the first electrode plate, the second electrode plate, and the separator in this order such that the organic support layer of the first current collector composite of the first electrode plate contacts one active material layer of the second electrode plate, and the other active material layer of the second electrode plate contacts the separator, to obtain a stacked structure, and winding the stacked structure, which is a method for manufacturing an electrode assembly.

19. A method for manufacturing an electrode assembly, comprising: Preparing a first electrode plate including a first current collector composite and a second electrode plate including a second current collector composite, wherein the first current collector composite and the second current collector composite are each the current collector composite according to any one of claims 1 to 11, and an active material layer is provided on the conductive layer of the current collector composite; Winding the first electrode plate and the second electrode plate such that the organic support layer of the first current collector composite of the first electrode plate contacts the active material layer of the second electrode plate, and the organic support layer of the second current collector composite of the second electrode plate contacts the active material layer of the first electrode plate, which is a method for manufacturing an electrode assembly.

20. A secondary battery, comprising: The secondary battery including the electrode assembly according to claim 12 or 13.

21. An electric power consuming device, comprising: The electric power consuming device including the secondary battery according to claim 20.

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