Composite collector

Abstract

Provided are a composite current collector and a manufacturing method thereof, and applications. The composite current collector includes a first metal layer (100), a second metal layer (200), and a polymer material layer (300). The polymer material layer (300) is located between the first metal layer (100) and the second metal layer (200). The composite current collector has a through-hole structure that penetrates the first metal layer (100), the second metal layer (200), and the polymer material layer (300). The through-hole structure has a pore diameter of 0.1 mm to 1 mm and a porosity of 0.1% to 5%. The composite current collector can conduct ions, reduce the polarization inside the battery, and improve the electrochemical performance of the battery.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and specifically, to a composite current collector and a method for manufacturing the same, as well as applications.

Background Art

[0002] Current metal composite current collectors are mainly copper current collectors or aluminum current collectors. Among them, both the copper current collector and the aluminum current collector consist of two parts, including a metal layer and a polymer layer located between the metal layers. However, the polymer layer in the middle of a normal metal composite current collector has a non-porous structure, that is, the porosity is 0, and the upper and lower metal layers cannot conduct ions on the upper and lower sides of the current collector. Therefore, there is a difference in the resistivity of the upper and lower metal layers, the formed ion field becomes non-uniform, the polarization inside the battery increases, and the electrochemical performance of the battery is affected.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Based on this, there is a need to provide a composite current collector and a method for manufacturing the same, as well as applications, which can conduct ions, reduce the polarization inside the battery, and improve the electrochemical performance of the battery.

Means for Solving the Problems

[0004] One aspect of the present invention provides a composite current collector including a first metal layer, a second metal layer, and a polymer material layer located between the first metal layer and the second metal layer, having a through-hole structure that penetrates the first metal layer, the second metal layer, and the polymer material layer, with a pore diameter of 0.1 mm to 1 mm and a porosity of 0.1% to 5%.

[0005] In some embodiments, the through-hole structure has a pore diameter of 0.5 mm to 1 mm and a porosity of 0.1% to 5%.

[0006] In some embodiments, the thickness of the composite current collector is 2 μm to 28 μm, the thicknesses of the first metal layer and the second metal layer may be separately 0.5 μm to 1.5 μm, and the thickness of the polymer material layer may be 1 μm to 25 μm.

[0007] In some embodiments, the material of the polymer material layer is selected from a composite of an insulating polymer material and an inorganic non-conductive filler, a composite of an insulating polymer material and a conductive filler, an insulating polymer material, or a conductive polymer material. The mass percentage of the insulating polymer material in the composite of the insulating polymer material and the inorganic non-conductive filler is 90% or more, and the mass percentage of the insulating polymer material in the composite of the insulating polymer material and the conductive filler is 90% or more.

[0008] In some embodiments, the insulating polymer material is cellulose and its derivatives, starch and its derivatives, protein and its derivatives, polyvinyl alcohol and its cross-linked polymers, polyethylene glycol and its cross-linked polymers, polyamide, , Poly-m-phenylene isophthalamide polyterephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, aramid, acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate, polybutylene terephthalate, polyparaphenylene terephthalamide, polypropylene ethylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, and polycarbonate, and / or the conductive polymer material is selected from doped poly sulfur nitride and / or doped polyacetylene, and / or The conductive filler is one or more selected from carbon black, carbon nanotubes, graphite, acetylene black, graphene, nickel, iron, copper, aluminum, alloys, graphite powder coated with nickel, and carbon fibers coated with nickel.

[0009] One aspect of the present invention is A method for manufacturing the above composite current collector is further provided, including forming the first metal layer and the second metal layer on both sides of the polymer material layer respectively, and perforating so as to penetrate the polymer material layer, the first metal layer and the second metal layer according to the distribution principle of the through-hole structure.

[0010] In some embodiments, the coating method is vacuum evaporation, and / or the perforating method is laser perforation. Optionally, the evaporation temperature of the evaporation material for the vacuum evaporation is 600°C to 1600°C, the degree of vacuum is less than 1×10 -2 Pa, and the evaporation rate is 10 m / min to 100 m / min. Optionally, the wavelength of the laser perforation is 400 nm to 700 nm.

[0011] Another aspect of the present invention further provides a positive electrode including the composite current collector described above and a positive electrode active material layer located on the surface of the composite current collector.

[0012] Yet another aspect of the present invention provides a battery including the positive electrode described above.

[0013] Still another aspect of the present invention further provides a power consumption device including the battery described above.

Advantages of the Invention

[0014] In the composite current collector related to the above, a porous composite current collector is manufactured by providing through holes and adjusting the pore diameter and distance of the through holes. When there is a difference in resistivity between the first metal layer and the second metal layer of the composite current collector and the ion fields do not match, ions can pass through the through-hole structure. As a result, the ion concentrations on the surfaces of the first metal layer and the second metal layer are gradually made substantially the same, the polarization on the surfaces of the first metal layer and the second metal layer of the composite current collector is reduced, the electrical performance of the battery is improved, especially the internal resistance of the battery is reduced, and its rate performance is improved.

Brief Description of the Drawings

[0015] To more clearly explain the specific embodiments of the present invention or the technical solutions in the prior art, the drawings necessary for use in the following description of the specific embodiments or the prior art will be briefly introduced below. The drawings in the following description are only some embodiments of the present invention, and it is obvious that those skilled in the art can obtain other drawings based on these drawings without creative labor.

[0016]

Figure 1

Figure 2

Explanation of Reference Numerals

[0017] 100 First metal layer, 200 Second metal layer, 300 Polymer material layer, 400 Pore channel.

Modes for Carrying Out the Invention

[0018] Provide a detailed reference to the embodiments of the present invention and explain one or more examples thereof below. Each example provided is for the purpose of interpreting the present invention and does not limit the present invention. In fact, it is obvious to those skilled in the art that various modifications and changes can be made to the present invention without departing from the scope or spirit of the present invention. For example, features described or depicted as part of one embodiment can be used in another embodiment to obtain a further embodiment.

[0019] Accordingly, it is intended to cover such modifications and changes as fall within the scope of the utility model registration claims appended hereto and the equivalents thereof. Other objects, features, and aspects of the present invention will be disclosed in or will become apparent from the following detailed description. It should be understood by those skilled in the art that this discussion is only an explanation of exemplary embodiments and is not intended to limit the broader aspects of the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used in this document have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In this document, the terms used in the specification of the present invention are only for the purpose of explaining specific examples and are not intended to limit the present invention. The term "and / or" used in this document includes any and all combinations of one or more of the associated listed items.

[0021] Unless otherwise indicated by what is shown in the examples of the operations or otherwise stated, all numbers used in the specification and the claims for utility model registration to represent the amounts of components, physicochemical properties, etc. are to be understood as being modified in all cases by the term "about". For example, thus, unless there is a contrary description, all numerical parameters recited in the above specification and the appended claims for utility model registration are approximate values, and those skilled in the art can appropriately change these approximate values by utilizing the desired properties required by the teachings disclosed in this manuscript. The use of numerical ranges indicated by endpoints includes all numbers within the range and any range within the range. For example, 1 to 5 includes 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4, and 5, etc.

[0022] The first object of the present invention is to provide a composite current collector including a first metal layer, a second metal layer, and a polymer material layer located between the first metal layer and the second metal layer, having a through-hole structure that penetrates the first metal layer, the second metal layer, and the polymer material layer, with a pore diameter of 0.1 mm to 1 mm and a porosity of 0.1% to 5%.

[0023] In the composite current collector related to the above, a porous composite current collector is manufactured by providing through-holes and adjusting the pore diameter and distance of the through-holes. When there is a difference in the resistivity between the first metal layer and the second metal layer of the composite current collector and the ion fields do not match, ions can pass through the through-hole structure. Thereby, the ion concentrations on the surfaces of the first metal layer and the second metal layer are made substantially the same, the polarization on the surfaces of the first metal layer and the second metal layer of the composite current collector is reduced, the electrical performance of the battery is improved, particularly the internal resistance of the battery is reduced, and its rate performance is improved.

[0024] In one embodiment, the pore diameter of the through-hole structure may be any value between 0.1 mm and 1 mm, preferably any value between 0.5 mm and 1 mm, and may be, for example, 0.6 mm, 0.7 mm, 0.8 mm, or 0.9 mm.

[0025] In one embodiment, the porosity may be any value between 0.1% and 5%, for example, it may be 0.5%, 1%, 2%, 3%, 4%, or 4.5%.

[0026] In one embodiment, the center distance between two adjacent through holes may be any value between 5 mm and 10 mm, for example, it may be 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, or 9.5 mm, and preferably, it is any value between 8 mm and 10 mm.

[0027] In one embodiment, the thickness of the composite current collector may be between 2 μm and 28 μm, for example, it may be 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, or 25 μm. Preferably, the thicknesses of the first metal layer and the second metal layer may each separately be between 0.5 μm and 1.5 μm, and the thickness of the polymer material layer may be between 1 μm and 25 μm.

[0028] In one embodiment, the material of the polymer material layer may be any material commonly used in this field, including but not limited to a composite of an insulating polymer material and an inorganic non-conductive filler, a composite of an insulating polymer material and a conductive filler, an insulating polymer material, or a conductive polymer material. In the composite of an insulating polymer material and an inorganic non-conductive filler, the mass percentage of the insulating polymer material is 90% or more, and in the composite of an insulating polymer material and a conductive filler, the mass percentage of the insulating polymer material is 90% or more.

[0029] The insulating polymer material includes cellulose and its derivatives, starch and its derivatives, protein and its derivatives, polyvinyl alcohol and its cross-linked polymers, polyethylene glycol and its cross-linked polymers, polyamide, polyterephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, aramid , Poly-m-phenylene isophthalamide, one or more selected from acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate, polybutylene terephthalate, polyparaphenylene terephthalamide, polypropylene ethylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber and polycarbonate may also be used, The conductive polymer material may be selected from doped poly sulfur nitride and / or doped polyacetylene.

[0030] The inorganic non-conductive filler may be one or more selected from ceramic materials, glass materials and ceramic composite materials, The conductive filler may be at least one selected from conductive carbon materials, metal materials and composite conductive materials. The carbon material may be selected from carbon black, carbon nanotubes, graphite, acetylene black and graphene. The metal material may be selected from nickel, iron, copper, aluminum and alloys. Among them, the alloy contains one or more of nickel, iron, copper and aluminum. The composite conductive material may be one or more selected from graphite powder coated with nickel and carbon fiber coated with nickel.

[0031] In one embodiment, the polymer material layer has a puncture strength of 100 gf or more, a longitudinal direction (MD) tensile strength of 180 MPa or more, a longitudinal direction (MD) elongation rate of 10% or more, a transverse direction (TD) tensile strength of 180 MPa or more, and a transverse direction (TD) elongation rate of 10% or more.

[0032] In one embodiment, the composite current collector is a positive current collector, and its puncture strength is 50 gf or more, the longitudinal direction (MD) tensile strength is 180 MPa or more, the longitudinal direction (MD) elongation rate is 10% or more, the transverse direction (TD) tensile strength is 180 MPa or more, and the transverse direction (TD) elongation rate is 10% or more.

[0033] In one embodiment, the peel force between the first metal layer and the second metal layer and the polymer material layer is 5 N / m or more.

[0034] In one embodiment, the first metal layer and the second metal layer may be a copper metal layer or an aluminum metal layer. Preferably, the purity of the first metal layer and the second metal layer is 99.8% or more.

[0035] One aspect of the present invention further provides a method for manufacturing the above composite current collector, including forming a first metal layer and a second metal layer on both sides of a polymer material layer respectively, and perforating through the polymer material layer, the first metal layer and the second metal layer according to the distribution principle of the through-hole structure.

[0036] In one embodiment, the coating method may be vacuum evaporation, and the parameters of the vacuum evaporation may be such that the evaporation temperature of the evaporation material is 600°C to 1600°C, the degree of vacuum is less than 1×10 -2 Pa, and the evaporation rate is 10 m / min to 100 m / min. For example, the degree of vacuum may be 0.1×10 -2 Pa to 0.8×10 -2 Pa. The evaporation rate is the moving speed of the polymer material layer.

[0037] In one embodiment, the perforating method may be laser perforation. Preferably, the wavelength of the laser perforation may be 400 nm to 700 nm.

[0038] In one embodiment, the manufacturing method further includes steps of winding and vacuum packaging.

[0039] Another aspect of the present invention further provides a positive electrode including the composite current collector described above and a positive electrode active material layer located on the surface of the composite current collector.

[0040] In one embodiment, the positive electrode active material in the positive electrode active material layer may be any positive electrode active material known in the art. For example, it may be lithium cobaltate, lithium iron phosphate, NCA, NCM, lithium manganate, lithium nickelate, NCMA or a cobalt-free positive electrode.

[0041] Yet another aspect of the present invention provides a battery including the positive electrode described above.

[0042] In one embodiment, the battery may further include a negative electrode and an electrolyte.

[0043] The negative electrode may similarly be any negative electrode commonly used in the art, such as graphite, lithium, or lithium titanate.

[0044] In one embodiment, the electrolyte may be a solid electrolyte, a semi-solid electrolyte, or a liquid electrolyte solution. The solid electrolyte and the semi-solid electrolyte may be an oxide electrolyte or a sulfide electrolyte, and the solute in the liquid electrolyte solution may be lithium hexafluorophosphate.

[0045] In one embodiment, the above battery may further include a separator, and the separator may be any separator known in the art, such as a PE wet separator, a PP dry separator, or a two-layer PE / PP coated separator.

[0046] The shape of the battery is not limited and may be, for example, cylindrical, square, or an aluminum laminate film pouch.

[0047] In one embodiment, the battery may be a lithium-ion battery.

[0048] Yet another aspect of the present invention further provides a power consumption device including the battery described above.

[0049] In one embodiment, specific types of the power consumption device include, but are not limited to, mobile terminals (such as mobile phones, mobile computers, etc.), smart wearable devices, power tools (such as electric drills, motors, etc.), electric vehicles, mobile batteries, etc.

[0050] Hereinafter, the present invention will be described in more detail with reference to specific examples and comparative examples.

[0051] Example 1 (1) Manufacture of the porous composite current collector As shown in FIGS. 1 and 2, in this embodiment, both the first metal layer 100 and the second metal layer 200 are metal aluminum layers, the polymer material layer 300 is a PET film, and the pore structure penetrates the porous composite current collector in its thickness direction to form pore channels 400. The specific manufacturing steps are as follows.

[0052] In step 1), a first metal aluminum layer and a second metal aluminum layer with a thickness of 1 μm and a purity of 99.9% are respectively vacuum-deposited on both sides of a PET film with a thickness of 6 μm to manufacture a composite current collector with a thickness of 8 μm. Among them, regarding the parameters of the vacuum deposition, specifically, the degree of vacuum is 0.5×10 -2 Pa, the temperature of the vapor deposition material is 650°C, and the vapor deposition rate is 100 m / min.

[0053] In step 2), the composite current collector manufactured in step 1) is perforated in its thickness direction by a laser drilling method to manufacture a porous composite current collector having pore channels 400. Among them, the depth of the pore channels 400 is 8 μm, the pore diameter is 0.5 mm, the center distance between adjacent circular holes is 8 mm, and the wavelength of the laser drilling is 600 nm.

[0054] The measured piercing strength of the porous composite current collector is 200 gf, the longitudinal direction (MD) tensile strength is 210 MPa, the longitudinal direction (MD) elongation rate is 35%, the transverse direction (TD) tensile strength is 190 MPa, and the transverse direction (TD) elongation rate is 15%.

[0055] The measured peeling force between the first metal layer 100 or the second metal layer 200 and the polymer material layer 300 is 5 N / m.

[0056] (2) Assembly of the battery The positive electrode is composed of the porous composite current collector manufactured in (1) and the lithium iron phosphate active material coated on the porous composite current collector. The negative electrode is graphite. The electrolyte is a liquid electrolyte with lithium hexafluorophosphate as the solute, The separator is a polyethylene (PE) microporous separator, The above components are assembled into a lithium iron phosphate battery with a model number of 50 Ah, and relevant performance tests are carried out. The test results are shown in Table 1.

[0057] Example 2 The method for manufacturing the porous composite current collector according to this example is almost the same as that of Example 1, but different in that the pore diameter is 1 mm. The specific steps are as follows.

[0058] As shown in FIGS. 1 and 2, in this example, both the first metal layer 100 and the second metal layer 200 are metal aluminum layers, the polymer material layer 300 is a PET film, and the pore structure penetrates the porous composite current collector in its thickness direction to form a pore channel 400. The specific manufacturing steps are as follows.

[0059] In step 1), a first metal aluminum layer and a second metal aluminum layer with a thickness of 1 μm and a purity of 99.9% are respectively vacuum-deposited on both sides of a PET film with a thickness of 6 μm to manufacture a composite current collector with a thickness of 8 μm. Among them, regarding the parameters of the vacuum deposition, specifically, the degree of vacuum is 0.5×10 -2 Pa, the temperature of the deposition material is 650 °C, and the deposition rate is 100 m / min.

[0060] In step 2), the composite current collector manufactured in step 1) is perforated in its thickness direction by a laser drilling method to manufacture a porous composite current collector. Among them, the depth of the pore channel 400 is 8 μm, the pore diameter is 1 mm, the center distance between adjacent circular holes is 8 mm, and the wavelength of the laser drilling is 600 nm.

[0061] Example 3 The method for manufacturing the porous composite current collector according to this example is almost the same as that of Example 1, but different in that the center distance between adjacent circular holes is 5 mm. The specific steps are as follows.

[0062] As shown in FIGS. 1 and 2, in this embodiment, both the first metal layer 100 and the second metal layer 200 are metal aluminum layers, the polymer material layer 300 is a PET film, and the pore structure penetrates the porous composite current collector in its thickness direction to form pore channels 400. The specific manufacturing steps are as follows.

[0063] In step 1), a first metal aluminum layer and a second metal aluminum layer with a thickness of 1 μm and a purity of 99.9% are respectively vacuum-deposited on both sides of a PET film with a thickness of 6 μm to manufacture a composite current collector with a thickness of 8 μm. Among them, regarding the parameters of the vacuum deposition, specifically, the vacuum degree is 0.5×10 -2 Pa, the temperature of the deposition material is 650 °C, and the deposition rate is 100 m / min.

[0064] In step 2), the composite current collector manufactured in step 1) is perforated in its thickness direction by a laser drilling method to manufacture a porous composite current collector. Among them, the depth of the pore channels 400 is 8 μm, the pore diameter is 0.5 mm, the center distance between adjacent circular holes is 5 mm, and the wavelength of the laser drilling is 500 nm.

[0065] Example 4 The method for manufacturing the porous composite current collector according to this embodiment is substantially the same as that of Example 1, but different in that the center distance between adjacent circular holes is 10 mm. The specific steps are as follows.

[0066] As shown in FIGS. 1 and 2, in this embodiment, both the first metal layer 100 and the second metal layer 200 are metal aluminum layers, the polymer material layer 300 is a PET film, and the pore structure penetrates the porous composite current collector in its thickness direction to form pore channels 400. The specific manufacturing steps are as follows.

[0067] In step 1), a first metal aluminum layer and a second metal aluminum layer, each with a thickness of 1 μm and a purity of 99.9%, are vacuum-deposited on both sides of a PET film with a thickness of 6 μm to produce a composite current collector with a thickness of 8 μm. Among them, specifically regarding the parameters of the vacuum deposition, the vacuum degree is 0.5×10 -2 Pa, the temperature of the deposition material is 650 °C, and the deposition rate is 100 m / min.

[0068] In step 2), the composite current collector produced in step 1) is perforated in its thickness direction by a laser drilling method to produce a porous composite current collector. Among them, the depth of the pore channel 400 is 8 μm, the pore diameter is 0.5 mm, the center distance between adjacent circular pores is 10 mm, and the wavelength of the laser drilling is 600 nm.

[0069] Example 5 The method for manufacturing the porous composite current collector according to this example is substantially the same as that of Example 1, except that the polymer material layer 300 is a conductive thin film made of polyethylene and graphite with a mass ratio of 9:1. The specific steps are as follows.

[0070] As shown in FIGS. 1 and 2, in this example, both the first metal layer 100 and the second metal layer 200 are metal aluminum layers, the polymer material layer 300 is a conductive thin film made of polyethylene and graphite (with a mass ratio of 9:1), and the pore structure penetrates the porous composite current collector in its thickness direction to form a pore channel 400. The specific manufacturing steps are as follows.

[0071] In step 1), a first metal aluminum layer and a second metal aluminum layer, each with a thickness of 1 μm and a purity of 99.9%, are vacuum-deposited on both sides of a conductive thin film made of polyethylene and graphite (with a mass ratio of 9:1) and having a thickness of 6 μm to produce a composite current collector with a thickness of 8 μm. Among them, specifically regarding the parameters of the vacuum deposition, the vacuum degree is 0.5×10 -2 Pa, the temperature of the deposition material is 650 °C, and the deposition rate is 100 m / min.

[0072] In step 2), the composite current collector manufactured in step 1) is perforated in its thickness direction by a laser drilling method to manufacture a porous composite current collector. Among them, the depth of the pore channel 400 is 8 μm, the pore diameter is 0.5 mm, the center distance between adjacent circular holes is 8 mm, and specifically, the wavelength of the laser drilling parameters is 600 nm.

[0073] Comparative Example 1 The manufacturing method of this comparative example is almost the same as that of Example 1, but it is different in that the current collector is not perforated, that is, the pore channel 400 is not formed. The specific steps are as follows.

[0074] (I) Manufacture of composite current collector In step 1), a first metal aluminum layer and a second metal aluminum layer with a thickness of 1 μm and a purity of 99.9% are respectively vacuum-deposited on both sides of a PET film with a thickness of 6 μm to manufacture a composite current collector with a thickness of 8 μm. Among them, specifically, the parameters of the vacuum deposition are that the vacuum degree is 0.5×10 -2 Pa, the temperature of the evaporation material is 650 °C, and the evaporation rate is 100 m / min.

[0075] The measured puncture strength of the composite current collector is 190 gf, the longitudinal direction (MD) tensile strength is 220 MPa, the longitudinal direction (MD) elongation rate is 43%, the transverse direction (TD) tensile strength is 200 MPa, and the transverse direction (TD) elongation rate is 21%.

[0076] The measured peel force between the first metal layer 100 or the second metal layer 200 and the polymer material layer 300 is 5 N / m.

[0077] (II) Assembly of battery The positive electrode is composed of the composite current collector manufactured in (I) and the lithium iron phosphate active material coated on the composite current collector. The negative electrode is graphite. The electrolyte is a liquid electrolyte with lithium hexafluorophosphate as the solute. The separator is a polyethylene (PE) microporous separator, The above-mentioned various components are assembled into a lithium iron phosphate battery with a model number of 50 Ah, and relevant performance tests are carried out. The test results are shown in Table 1.

[0078] Comparative Example 2 The manufacturing method of this comparative example is almost the same as that of Example 1, but it is different in that the pore diameter is 2 mm. The specific steps are as follows.

[0079] (1) Manufacture of the porous composite current collector As shown in FIGS. 1 and 2, in this example, both the first metal layer 100 and the second metal layer 200 are metal aluminum layers, the polymer material layer 300 is a PET film, and the pore structure penetrates the porous composite current collector in its thickness direction to form pore channels 400. The specific manufacturing steps are as follows.

[0080] In step 1), a first metal aluminum layer and a second metal aluminum layer with a thickness of 1 μm and a purity of 99.9% are respectively vacuum-deposited on both sides of a PET film with a thickness of 6 μm to manufacture a composite current collector with a thickness of 8 μm. Among them, regarding the parameters of the vacuum deposition, specifically, the vacuum degree is 0.5×10 -2 Pa, the temperature of the vapor deposition material is 650 °C, and the vapor deposition rate is 100 m / min.

[0081] In step 2), the composite current collector manufactured in step 1) is perforated in its thickness direction by a laser drilling method to manufacture a porous composite current collector having pore channels 400. Among them, the depth of the pore channels 400 is 8 μm, the pore diameter is 2 mm, the center distance between adjacent circular holes is 8 mm, and regarding the parameters of the laser drilling, specifically, the wavelength is 600 nm.

[0082] (2) Assembly of the battery The positive electrode is composed of the porous composite current collector manufactured in (1) and the lithium iron phosphate active material coated on the porous composite current collector, The negative electrode is graphite, The electrolyte is a liquid electrolyte with lithium hexafluorophosphate as the solute. The separator is a polyethylene (PE) microporous separator. The above components are assembled into a lithium iron phosphate battery with a model number of 50 Ah, and related performance tests are conducted. The test results are shown in Table 1.

[0083] Performance Test For the polarization internal resistance test, capacity retention rate, and charge-discharge cycle performance test, refer to Chinese national standard GB18287_2000, and the test results are shown in Table 1.

[0084] 1) Regarding the capacity retention rate, at 25°C, cycle 1000 times at a 3C rate, and test the capacity retention rate of the lithium iron phosphate batteries assembled in Example 1 and Comparative Examples 1-2. The test results are shown in Table 1.

[0085] 2) Regarding the charge-discharge cycle performance test, when the capacity retention rate is 80%, measure the cycle performance of the lithium iron phosphate batteries assembled in Example 1 and Comparative Examples 1-2 at a 1C rate charge and 1C rate discharge (1C / 1C), and show the number of cycles in Table 1.

[0086]

Table 1

[0087] As can be seen from the above test results, by providing a pore structure in the composite current collector, the ion concentrations of the upper and lower metal layers of the current collector can be made substantially the same. Thereby, the polarization on the surfaces of the upper and lower metal layers of the porous composite current collector is reduced, and the electrical performance of the battery, especially the internal resistance and rate performance of the battery, is improved. Also, by further adjusting parameters of the pore structure such as the pore diameter and the center distance between pores, etc., the porous composite current collector can have excellent mechanical strength while reducing its polarization. Also, when the pore diameter increases or the number of pores increases, the strength of the composite current collector also decreases.

[0088] Each of the technical features of the above embodiments can be arbitrarily combined. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, all of them should be regarded as within the scope described in this specification.

[0089] The above embodiments only illustrate some embodiments of the present invention, and the description is specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be noted that those skilled in the art can make some modifications and improvements to the present invention on the premise of not departing from the concept of the present invention, and all of these belong to the scope of the present invention. Therefore, the protection scope of the present invention should be based on the scope of claims of the attached utility model registration.

Claims

1. A composite current collector comprising a first metal layer, a second metal layer, and a polymer material layer located between the first metal layer and the second metal layer, having a through-hole structure that penetrates the first metal layer, the second metal layer, and the polymer material layer, with a pore diameter of 0.1 mm to 1 mm and a porosity of 0.1% to 5%.

2. The composite current collector according to claim 1, wherein the through-hole structure has a pore diameter of 0.5 mm to 1 mm and a porosity of 0.1% to 5%.

3. The thickness is 2 μm to 28 μm, and the thicknesses of the first metal layer and the second metal layer may each be separately 0.5 μm to 1.5 μm, and the thickness of the polymer material layer may be 1 μm to 25 μm. The composite current collector according to claim 1, characterized in that.

4. The material of the polymer material layer is selected from a composite of an insulating polymer material and an inorganic non-conductive filler, a composite of an insulating polymer material and a conductive filler, an insulating polymer material, or a conductive polymer material. In the composite of the insulating polymer material and the inorganic non-conductive filler, the mass percentage of the insulating polymer material is 90% or more, and in the composite of the insulating polymer material and the conductive filler, the mass percentage of the insulating polymer material is 90% or more. The composite current collector according to any one of claims 1 to 3, characterized in that.

5. The insulating polymer material is one or more selected from cellulose and its derivatives, starch and its derivatives, protein and its derivatives, polyvinyl alcohol and its cross-linked polymers, polyethylene glycol and its cross-linked polymers, polyamide, polyterephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, aramid, polydiformylphenylenediamine, acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate, polybutylene terephthalate, polyparaphenylene terephthalamide, polypropylene ethylene, polyoxymethylene, epoxy resin, phenol resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, and polycarbonate, and / or, The conductive polymer material is selected from doped poly sulfur nitride and / or doped polyacetylene, and / or, The inorganic non-conductive filler is one or more selected from ceramic materials, glass materials, and ceramic composite materials, and / or the conductive filler is one or more selected from carbon black, carbon nanotubes, graphite, acetylene black, graphene, nickel, iron, copper, aluminum, alloys, graphite powder coated with nickel, and carbon fiber coated with nickel. The composite current collector according to claim 4, wherein

6. A method for manufacturing the composite current collector according to any one of claims 1 to 5, forming the first metal layer and the second metal layer on both sides of the polymer material layer, respectively, and including a step of perforating so as to penetrate the polymer material layer, the first metal layer, and the second metal layer according to the distribution principle of the through-hole structure. A method for manufacturing a composite current collector, characterized in that

7. the plating method is vacuum evaporation, and / or the perforating method is laser perforation, Optionally, the evaporation temperature of the plating material for vacuum evaporation is 600°C to 1600°C, the degree of vacuum is less than 1×10 －２ Pa, and the deposition rate is 10 m / min to 100 m / min. optionally, the wavelength of the laser perforation is 400 nm to 700 nm. The method for manufacturing a composite current collector according to claim 6, characterized in that

8. A positive electrode comprising the composite current collector according to any one of claims 1 to 5 and a positive electrode active material layer located on the surface of the composite current collector, characterized in that

9. A battery comprising the positive electrode according to claim 8, characterized in that

10. A power consumption device comprising the battery according to claim 9, characterized in that

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