WO2024092882A1 - 复合铜集流体及其制备方法、极片、二次电池和用电装置 - Google Patents

复合铜集流体及其制备方法、极片、二次电池和用电装置 Download PDF

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WO2024092882A1
WO2024092882A1 PCT/CN2022/132110 CN2022132110W WO2024092882A1 WO 2024092882 A1 WO2024092882 A1 WO 2024092882A1 CN 2022132110 W CN2022132110 W CN 2022132110W WO 2024092882 A1 WO2024092882 A1 WO 2024092882A1
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layer
current collector
copper current
composite copper
polymer substrate
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PCT/CN2022/132110
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English (en)
French (fr)
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朱中亚
蒋文强
王帅
夏建中
李学法
张国平
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扬州纳力新材料科技有限公司
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Publication of WO2024092882A1 publication Critical patent/WO2024092882A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/04—Construction or manufacture in general
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of electrochemical technology, and in particular to a composite copper current collector and a preparation method thereof, a pole piece, a secondary battery and an electrical device.
  • composite copper current collectors based on polymer films have received extensive attention and application in the new energy industry.
  • Conventional composite copper current collectors usually include a polymer film layer and a metal copper layer formed on the polymer film layer by methods such as physical vapor deposition (PVD).
  • the corresponding preparation process usually includes: (1) depositing a layer of copper on the polymer film by physical vapor deposition (magnetron sputtering or evaporation) to prepare a composite copper current collector semi-finished product with a certain conductivity; (2) further treating the composite copper current collector semi-finished product by electroplating to prepare a composite copper current collector.
  • PVD physical vapor deposition
  • composite copper current collectors to reduce the cost of secondary batteries and improve the energy density and safety of batteries when used in secondary batteries.
  • the physical vapor deposition process involved in the preparation of conventional composite copper current collectors has the problem of high energy consumption, which will lead to an increase in the cost of composite copper current collectors.
  • the present application provides a composite copper current collector and a preparation method thereof, a pole piece, a secondary battery and an electrical device, which can reduce the energy consumption of preparing the composite copper current collector, thereby reducing the cost.
  • the first aspect of the present application provides a composite copper current collector, comprising:
  • an intermediate transition layer disposed on at least one side surface of the polymer substrate layer, wherein the intermediate transition layer comprises carbon nanomaterials and cellulose nanofibers;
  • a copper layer is disposed on a surface of the intermediate transition layer at a side relatively far from the polymer substrate layer.
  • the composite copper current collector satisfies at least one of the following conditions:
  • the mass proportion of the carbon nanomaterial in the intermediate transition layer is 52% to 88%;
  • the carbon nanomaterial comprises one or more of carbon nanotubes, graphene and carbon nanofibers.
  • the carbon nanotubes are single-walled carbon nanotubes.
  • the single-walled carbon nanotube has a diameter of 2 nm to 10 nm and a length of 1 ⁇ m to 5 ⁇ m.
  • the composite copper current collector satisfies at least one of the following conditions:
  • the graphene sheet has a diameter of 0.5 ⁇ m to 5 ⁇ m and a thickness of 0.8 nm to 1.2 nm;
  • the carbon nanofibers have a diameter of 50 nm to 200 nm and a length of 1 ⁇ m to 15 ⁇ m;
  • the cellulose nanofibers have a diameter of 5 nm to 20 nm, a length of 5 ⁇ m to 10 ⁇ m, and a carboxyl content of 0.5 mmol/g to 1.5 mmol/g.
  • the composite copper current collector satisfies at least one of the following conditions:
  • the thickness of the polymer substrate layer is 2 ⁇ m to 20 ⁇ m;
  • the thickness of the intermediate transition layer is greater than 500 nm, and can be selected to be 500 nm to 1500 nm;
  • the thickness of the copper layer is 500nm to 2000nm, and can be optionally 700nm to 1200nm.
  • the composite copper current collector satisfies at least one of the following conditions:
  • the polymer substrate layer contains at least one hole, and optionally, the average pore size of the hole is 50 nm to 150 nm;
  • the polymer substrate includes one or more of polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyimide, polypropylene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, polystyrene, polyamide and derivatives of the above polymers.
  • the composite copper current collector further includes a protective layer, which is disposed on the surface of the copper layer relatively away from the intermediate transition layer.
  • the protective layer has a thickness of 10 nm to 150 nm.
  • the composite copper current collector satisfies at least one of the following conditions:
  • the thickness of the protective layer is 20 nm to 100 nm.
  • the thickness of the protective layer is not more than one tenth of the thickness of the metal layer;
  • the material of the protective layer includes one or more of nickel, chromium, nickel-based alloy, copper-based alloy, copper oxide, aluminum oxide, nickel oxide, chromium oxide, cobalt oxide, graphite, carbon black, acetylene black, Ketjen black, carbon nano-quantum dots, carbon nanotubes, carbon nanofibers and graphene.
  • the second aspect of the present application provides a method for preparing a composite copper current collector, comprising:
  • the composite film is subjected to electroplating treatment, and a copper layer is deposited on the surface of the intermediate transition layer on the side away from the polymer substrate layer to obtain a composite copper current collector.
  • the method satisfies at least one of the following conditions:
  • the mass percentage concentration of the carbon nanomaterial in the transition liquid is 0.30wt.% to 1.0wt.%;
  • the ratio of the mass percentage concentration of the carbon nanomaterial to the mass percentage concentration of the cellulose nanofibers in the transition liquid is 4:1 to 8:1;
  • the transition liquid further comprises a surfactant, and optionally, the mass percentage concentration of the surfactant is 0.02wt.% to 0.2wt.%;
  • the surfactant includes one or more of sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, cetyltrimethylammonium bromide, sodium dodecyl sulfonate, polysorbate-20, polysorbate-80, polyoxyethylene monolaurate, polyoxyethylene monolaurate, disodium lauryl sulfosuccinate, potassium monododecyl phosphate and lauramidopropyl dimethylamine betaine;
  • the coating thickness of the transition liquid is 80 ⁇ m to 200 ⁇ m.
  • the method before coating the transition liquid on the surface of at least one side of the polymer substrate layer, the method further comprises:
  • the surface of the polymer substrate film is subjected to corona treatment to obtain the polymer substrate layer.
  • the power of the corona treatment is 10 kW to 30 kW;
  • the line speed of the corona treatment is 50 m/min to 200 m/min.
  • the method further comprises:
  • a protective layer is prepared on the surface of the copper layer away from the intermediate transition layer.
  • the method for preparing the protective layer includes one or more of physical vapor deposition, chemical vapor deposition, in-situ forming and coating.
  • the third aspect of the present application provides a pole piece, comprising the composite copper current collector of the first aspect of the present application or the composite copper current collector prepared according to the method of the second aspect of the present application.
  • the electrode sheet includes a positive electrode sheet and/or a negative electrode sheet.
  • the fourth aspect of the present application provides a secondary battery, comprising the electrode sheet of the third aspect of the present application.
  • a fifth aspect of the present application provides an electrical device, comprising the secondary battery of the fourth aspect of the present application.
  • the electric device of the present application includes the secondary battery provided by the present application, and thus has at least the same advantages as the secondary battery.
  • FIG1 is a schematic structural diagram of a composite copper current collector according to an embodiment of the present application.
  • FIG. 2 is a schematic structural diagram of a composite copper current collector according to another embodiment of the present application.
  • any lower limit can be combined with any upper limit to form an unclearly recorded range; and any lower limit can be combined with other lower limits to form an unclearly recorded range, and any upper limit can be combined with any other upper limit to form an unclearly recorded range.
  • each point or single value between the range endpoints is included in the range.
  • each point or single value can be combined as its own lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an unclearly recorded range.
  • a list of items connected by the terms “at least one of,” “at least one of,” “at least one of,” or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, the phrase “at least one of A and B” means only A; only B; or A and B. In another example, if items A, B, and C are listed, the phrase “at least one of A, B, and C” means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C.
  • Item A may contain a single component or multiple components.
  • Item B may contain a single component or multiple components.
  • Item C may contain a single component or multiple components.
  • the inventor discovered unexpectedly during the research process that in the current conventional composite copper current collector preparation process, the composite copper current collector semi-finished product prepared on the polymer film layer by physical vapor deposition will have hole defects on its surface. Since the hole defects are not conductive, copper atoms cannot be deposited at the hole defects during the subsequent electroplating process, so that the prepared composite copper current collector also has hole defects, affecting the performance and application of the composite copper current collector.
  • the inventor proposed the following technical solution of this application from the perspective of reducing and eliminating hole defects.
  • a first aspect of the embodiments of the present application provides a method for preparing a composite copper current collector, which may include the following steps:
  • the method provided in the present application firstly uses a surface coating process to coat an intermediate transition layer containing carbon nanomaterials and cellulose nanofibers on the surface of a polymer substrate layer, and then uses electroplating to deposit a copper layer on the surface of the intermediate transition layer to obtain a composite copper current collector.
  • the surface coating process can be used to replace the conventional physical vapor deposition process, and then the surface hole defects and other problems caused by the physical vapor deposition method in the preparation of the composite copper current collector can be avoided, the surface hole defects can be reduced or eliminated, and the performance of the composite copper current collector can be improved.
  • the preparation energy consumption increased by physical vapor deposition can also be reduced, which is conducive to reducing costs.
  • the formed intermediate transition layer also contains carbon nanomaterials and cellulose nanofibers, wherein the carbon nanomaterials can provide conductivity, which is beneficial to the deposition of the copper layer on the intermediate transition layer; and the cellulose nanofibers can provide adhesion, enhancing the adhesion between the intermediate transition layer and the polymer substrate layer.
  • step S10 may include two steps of coating and drying, namely:
  • the coating method of coating the transition liquid on the polymer substrate layer is not particularly limited and can be selected according to actual needs.
  • the coating method can be one or more of slit extrusion coating, blade coating, and extrusion coating.
  • the polymer substrate layer coated with the transition liquid coating layer on the surface may be placed in a hot air oven and dried at 70° C. to 100° C.
  • the mass percentage concentration of the carbon nanomaterial in the transition liquid is 0.30 wt.% to 1.0 wt.%.
  • the intermediate transition layer can have sufficient conductivity, thereby facilitating the deposition of the copper layer.
  • the ratio of the mass percentage concentration of the carbon nanomaterial to the mass percentage concentration of the cellulose nanofiber in the transition liquid is 4:1 to 8:1.
  • the ratio of the mass percentage concentration of the carbon nanomaterial to the mass percentage concentration of the cellulose nanofiber is within a suitable range, which can not only make the intermediate transition layer have sufficient conductivity, but also provide sufficient bonding performance for the intermediate transition layer. If the ratio of the two is low, the carbon nanomaterial content is too low, which may cause poor conductivity; if the ratio of the two is high, the carbon nanomaterial content is too high, and it is easy to agglomerate, resulting in poor conductivity.
  • the transition liquid further comprises a surfactant
  • the type of the surfactant is not particularly limited and can be selected according to actual needs.
  • the surfactant can include one or more of sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, sodium dodecyl sulfonate, polysorbate-20, polysorbate-80, polyoxyethylene monolaurate, polyoxyethylene monolaurate, disodium lauryl sulfosuccinate, potassium monododecyl phosphate, and lauramide propyl dimethylamine betaine.
  • the mass percentage concentration of the surfactant is 0.02 wt.% to 0.2 wt.%.
  • the mass percentage concentration of the surfactant within a suitable range is beneficial to promoting the dispersibility of the carbon nanomaterial in the transition liquid.
  • the type of the polymer substrate is not particularly limited and can be selected according to actual needs.
  • the polymer substrate can include one or more of materials such as polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polypropylene, polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polystyrene (PS), polyimide (PI) and their derivatives.
  • the polymer substrate is a porous structure with an average pore size of 50nm to 150nm. When the pore size is too small or too large, it is easy to cause the bonding force of the polymer substrate layer and the intermediate transition layer to decrease.
  • the polymer substrate layer can be prepared by a melt-extrusion-biaxial stretching method.
  • the coating thickness of the transition liquid is 80 ⁇ m to 200 ⁇ m. If the coating thickness is low, the intermediate transition layer is thin, which may result in poor conductivity and poor subsequent electroplating effect; if the coating thickness is high, the intermediate transition layer is thick, which may increase the thickness of the composite copper current collector and be unfavorable for the application of the composite copper current collector in secondary batteries.
  • the electroplating solution in the electroplating process in step S20 may include copper sulfate, sulfuric acid, concentrated hydrochloric acid, electrolyte additives, and other substances required for electroplating.
  • the concentration of copper sulfate can be 100 g/L to 180 g/L.
  • the concentration of copper sulfate can be 110 g/L, 120 g/L, 130 g/L, 140 g/L, 150 g/L, 160 g/L, 170 g/L, or within a range consisting of any of the above values.
  • the concentration of sulfuric acid can be 60 g/L to 120 g/L.
  • the concentration of sulfuric acid can be 70 g/L, 80 g/L, 90 g/L, 100 g/L, 110 g/L, or within a range consisting of any of the above values.
  • the concentration of concentrated hydrochloric acid can be 60 mg/L to 100 mg/L.
  • the concentration of concentrated hydrochloric acid can be 70 g/L, 80 g/L, 90 g/L or within a range consisting of any of the above values.
  • the concentration of the electrolyte additive may be 3 mg/L to 10 mg/L.
  • the concentration of the electrolyte additive may be 4 mg/L, 5 mg/L, 6 mg/L, 7 mg/L, 8 mg/L, 9 mg/L, or within a range of any of the above values.
  • the type of electrolyte additive is not particularly limited and can be selected according to actual needs.
  • the electrolyte additive can be one or more of a complexing agent, a promoter, and an inhibitor.
  • the complexing agent can include one or more of potassium sodium tartrate, sodium citrate, disodium ethylenediaminetetraacetate, and triethanolamine;
  • the promoter can include at least one of sodium polydisulfide propane sulfonate and sodium 3-mercapto-1-propane sulfonate; and the inhibitor can be polyethylene glycol.
  • the temperature of the electroplating solution can be controlled to be 25° C.
  • the average cathode current density can be controlled to be 1 A/dm 2 to 3 A/dm 2 .
  • step S10 the following steps are also included:
  • Performing corona treatment on the surface of the polymer substrate film in step S30 is beneficial to increasing the surface tension of the film and promoting the bonding force between the polymer substrate layer and the intermediate transition layer.
  • the power of the corona treatment may be 10 kW to 30 kW, and the current may be 4 A to 10 A.
  • the line speed of the corona treatment may be 50 m/min to 200 m/min.
  • Controlling the power and other parameters of the corona treatment within a suitable range is beneficial to further increase the surface tension of the film and promote the adhesion between the polymer substrate layer and the intermediate transition layer.
  • step S20 the following steps are further included:
  • step S40 The preparation of the protective layer in step S40 is helpful to prevent the conductive layer from being chemically corroded or physically damaged.
  • the method for preparing the protective layer includes one or more of physical vapor deposition, chemical vapor deposition, in-situ forming method and coating method.
  • physical vapor deposition is preferably vacuum evaporation and magnetron sputtering
  • chemical vapor deposition is preferably atmospheric pressure chemical vapor deposition and plasma enhanced chemical vapor deposition
  • the in-situ forming method is preferably a method of in-situ forming a metal oxide passivation layer on the surface of the metal layer
  • the coating method is preferably die coating, blade coating and extrusion coating.
  • the composite film layer formed after the electroplating treatment in step S20 can be cleaned in a pure water tank, and then passivated in a passivation tank to prepare a protective layer.
  • the passivation temperature can be 25°C
  • the passivation solution can be a 5g/L aqueous solution of potassium dichromate or chromic anhydride, and finally cleaned in a pure water tank. After cleaning, it can be dried in an oven at 70°C to 90°C to obtain a composite copper current collector containing a protective layer.
  • the second aspect of the embodiment of the present application provides a composite copper current collector, which can be prepared according to the method of the first aspect of the embodiment of the present application.
  • the composite copper current collector includes a polymer substrate layer 1, an intermediate transition layer 2 arranged on at least one side surface of the polymer substrate layer 1, and a copper layer 3 arranged on the surface of the intermediate transition layer on the side relatively away from the polymer substrate layer; wherein the intermediate transition layer 2 contains carbon nanomaterials and cellulose nanofibers.
  • the composite copper current collector provided by the present application has an intermediate transition layer between the polymer substrate layer and the copper layer, which can separate the polymer substrate layer from the copper layer, reduce or eliminate the hole defects formed when the polymer substrate layer and the copper layer are directly contacted and composited, and improve the performance of the composite copper current collector.
  • the carbon nanomaterial contained in the intermediate transition layer can provide conductivity and enhance the conductivity of the composite copper current collector; and the cellulose nanofiber contained in the intermediate transition layer can provide adhesion, enhance the adhesion between the intermediate transition layer and the polymer substrate layer, and improve the structural stability of the composite copper current collector.
  • the mass proportion of the carbon nanomaterial in the intermediate transition layer is 52% to 88%.
  • the mass proportion of the carbon nanomaterial in the intermediate transition layer is within a suitable range, which can effectively improve the conductivity of the composite copper current collector.
  • the mass proportion of the cellulose nanofibers in the intermediate transition layer is 7% to 20%.
  • the mass proportion of the cellulose nanofibers in the intermediate transition layer is within a suitable range, which can ensure that the intermediate transition layer and the polymer substrate layer have sufficient bonding force, so that the composite copper current collector has a higher structural stability.
  • the type of carbon nanomaterial is not specifically limited and can be selected according to actual needs.
  • the carbon nanomaterial includes one or more of carbon nanotubes, graphene, and carbon nanofibers.
  • the carbon nanotube is a single-walled carbon nanotube.
  • the single-walled carbon nanotube has a diameter of 2 nm to 10 nm and a length of 1 ⁇ m to 5 ⁇ m.
  • the graphene sheet has a diameter of 0.5 ⁇ m to 5 ⁇ m and a thickness of 0.8 nm to 1.2 nm.
  • the carbon nanofibers have a diameter of 50 nm to 200 nm and a length of 1 ⁇ m to 15 ⁇ m.
  • the size of the carbon nanomaterial is controlled within a suitable range, which is beneficial to improving the conductivity of the intermediate transition layer. If the size is smaller, the conductivity will be poor; if the size is larger, the uniformity and conductivity of the intermediate transition layer will deteriorate.
  • the cellulose nanofibers have a diameter of 5 nm to 20 nm, a length of 5 ⁇ m to 10 ⁇ m, and a carboxyl content of 0.5 mmol/g to 1.5 mmol/g. If the size of the cellulose nanofibers is small, it is not easy to effectively bond the carbon nanotubes; if the size of the cellulose nanofibers is large, the uniformity and conductivity of the intermediate transition layer will deteriorate.
  • the carboxyl content of the cellulose nanofibers is low, the dispersibility of the cellulose nanofibers is poor, which can easily lead to a poor coating effect of the transition liquid; if the carboxyl content is high, it is not easy to effectively bond the carbon nanotubes, resulting in poor stability of the intermediate transition layer.
  • the thickness of the polymer substrate layer is 2 ⁇ m to 20 ⁇ m.
  • the thickness of the polymer substrate layer is controlled within a suitable range, which can meet the application requirements of the composite copper-collecting fluid while taking into account the difficulty and cost of the preparation process.
  • the polymer substrate layer contains at least one hole, and optionally, the average pore size of the hole is 50 nm to 150 nm.
  • the hole in the polymer substrate layer can further enhance the bonding force between the intermediate transition layer and the polymer substrate layer. When the pore size is small or large, it is easy to cause the bonding force between the polymer substrate layer and the intermediate transition layer to decrease.
  • the type of polymer substrate is not particularly limited and can be selected according to actual needs.
  • the polymer substrate can include one or more of polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyimide, polypropylene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, polystyrene, polyamide and derivatives of the above polymers.
  • the thickness of the intermediate transition layer is greater than 500 nm, and can be selected from 500 nm to 1500 nm.
  • the intermediate transition layer can give the polymer substrate layer a certain conductivity, thereby achieving the purpose of preparing the copper layer by electroplating.
  • its thickness should not be less than 500 nm; further considering the requirements of the battery application end for the thin composite copper current collector, the thickness of the intermediate transition layer can be selected from 500 nm to 1500 nm.
  • the intermediate transition layer can be set on the surface of one side of the polymer substrate layer, or it can be set on the surfaces of the opposite sides of the polymer substrate layer at the same time; when set at the same time, the thickness of the intermediate transition layers on both sides can be the same or different, and the specific setting method can be selected according to actual needs.
  • the copper layer has a thickness of 500 nm to 2000 nm, and can be 700 nm to 1200 nm. In the embodiments of the present application, the copper layer can play a role of conducting electricity.
  • the copper layer can be arranged on the surface of the intermediate transition layer located on one side of the polymer substrate layer, or can be arranged on the surface of the intermediate transition layer located on both sides of the polymer substrate layer at the same time; when set at the same time, the thickness of the copper layer on both sides can be the same or different, and the specific setting method can be selected according to actual needs.
  • the composite copper current collector may further include a protective layer 4 , and the protective layer 4 is disposed on a surface of the copper layer 3 that is relatively far from the intermediate transition layer 2 .
  • the thickness of the protective layer is 10 nm to 150 nm, and the thickness of the protective layer is no more than one tenth of the thickness of the metal layer.
  • the thickness of the protective layer is 20 nm to 100 nm.
  • the protective layer is mainly used to prevent the conductive layer from being chemically corroded or physically damaged.
  • the thickness of the protective layer is within an appropriate range, which can provide a good protective effect while not affecting the conductivity of the conductive layer. If the protective layer is too thin, the protective effect will not be obvious; if the protective layer is too thick, the conductivity may be affected.
  • the material of the protective layer includes one or more of nickel, chromium, nickel-based alloys, copper-based alloys, copper oxide, aluminum oxide, nickel oxide, chromium oxide, cobalt oxide, graphite, carbon black, acetylene black, Ketjen black, carbon nano-quantum dots, carbon nanotubes, carbon nanofibers and graphene.
  • the protective layer can be set on the surface of the copper layer located on one side of the polymer substrate layer, or can be set on the surface of the copper layer located on both sides of the polymer substrate layer at the same time; when set at the same time, the material and thickness of the protective layers on both sides must be consistent.
  • a third aspect of the embodiments of the present application provides a pole piece, comprising the composite copper current collector of the first aspect of the present application or the composite copper current collector prepared by the method of the second aspect of the present application.
  • the electrode sheet includes a positive electrode sheet and/or a negative electrode sheet.
  • a fourth aspect of the embodiments of the present application provides a secondary battery, comprising the electrode sheet according to the third aspect of the present application.
  • the secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator.
  • active ions are embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet.
  • the electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet.
  • the separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.
  • the fifth aspect of the embodiment of the present application provides an electrical device, including the secondary battery of the fourth aspect of the present application.
  • the secondary battery can be used as a power source for the device, and can also be used as an energy storage unit for the device.
  • the device can be, but is not limited to, a mobile device, an electric vehicle, an electric train, a ship and a satellite, an energy storage system, etc.
  • it can be a notebook computer, a pen-input computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini CD, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large household battery, etc.
  • a porous polypropylene film with a thickness of 3 ⁇ m and an average pore size of 50 nm was selected as the base film and placed in a corona treatment device.
  • the corona treatment power was 10 kW
  • the current was 4 A
  • the treatment line speed was 50 m/min, so as to obtain a corona-treated polypropylene film.
  • a certain amount of single-walled carbon nanotubes (diameter 2 nm, length 1 ⁇ m), cellulose nanofibers (2 wt.% hydrogel, fibers with a diameter of 5.0 nm, a length of 5.0 ⁇ m, and a carboxyl content of 0.5 mmol/g), and sodium dodecylbenzene sulfonate were weighed and added to pure water.
  • the mixture was stirred for 10 min and then ultrasonically dispersed for 60 min (ultrasonic power of 600 W and ultrasonic frequency of 40 kHz) to obtain a uniform aqueous dispersion of 0.30 wt.% carbon nanotubes, 0.075 wt.% cellulose nanofibers, and 0.02 wt.% sodium dodecylbenzene sulfonate, i.e., the concentration ratio of carbon nanotubes to cellulose nanofibers was 4:1.
  • a corona-treated polypropylene film was used as the substrate and placed 2 mm below the slit extrusion die.
  • the prepared coating liquid was extruded from the slit extrusion die and evenly coated on the polypropylene film.
  • the coating thickness was 150 ⁇ m. After coating, it was placed in a 100°C hot air oven for drying. After drying, the above coating-drying treatment was repeated on the other side of the base film to obtain a polypropylene film (composite copper current collector semi-finished product) with an intermediate transition layer on the surface.
  • the polypropylene film with the intermediate transition layer on the surface prepared above is placed in an electroplating device for electroplating.
  • the electroplating is divided into the following three steps:
  • the electroplating solution is 150 g/L copper sulfate, 120 g/L sulfuric acid, 60 mg/L concentrated hydrochloric acid, 7 mL/L electrolyte additive (LD-5120M product of Chongqing Lidao Company), the electroplating solution temperature is 25°C, and the average cathode current density is 2 A/dm 2 .
  • Passivation After electroplating, the plated film is placed in a pure water cleaning tank for cleaning, and then passivated in a passivation tank to prepare a surface protective layer.
  • the passivation solution is a 5g/L potassium dichromate aqueous solution at a temperature of 25°C, and finally cleaned in a pure water tank.
  • Drying Dry the cleaned composite film in an oven at 70° C. to prepare an electroplated conductive copper layer and a protective layer with a coating thickness of 1 ⁇ m, that is, to obtain a composite copper current collector.
  • Example 2 It is basically the same as Example 1, except that the concentration of the cellulose nanofibers in the coating solution is 0.050 wt.%, that is, the concentration ratio of the carbon nanotubes to the cellulose nanofibers is 6:1.
  • Example 2 It is basically the same as Example 1, except that the concentration of the cellulose nanofibers in the coating solution is 0.0375 wt.%, that is, the concentration ratio of the carbon nanotubes to the cellulose nanofibers is 8:1.
  • the method is basically the same as Example 2, except that the concentration of carbon nanotubes in the coating solution is 0.60 wt.%, and the concentration of cellulose nanofibers is 0.10 wt.%.
  • the method is basically the same as Example 2, except that the concentration of carbon nanotubes in the coating solution is 1.00 wt.%, and the concentration of cellulose nanofibers is 0.1667 wt.%.
  • the method is basically the same as Example 4, except that the concentration of sodium dodecylbenzenesulfonate in the coating liquid is 0.1 wt.%.
  • the method is basically the same as Example 4, except that the concentration of sodium dodecylbenzene sulfonate in the coating liquid is 0.2 wt.%.
  • Example 6 It is basically the same as Example 6, except that the average pore size of the porous polypropylene membrane is 100 nm.
  • Example 6 It is basically the same as Example 6, except that the average pore size of the porous polypropylene membrane is 150 nm.
  • Example 8 It is basically the same as Example 8, except that the diameter of the carbon nanotube is 6 nm and the length is 3 ⁇ m.
  • Example 8 It is basically the same as Example 8, except that the diameter of the carbon nanotube is 10 nm and the length is 5 ⁇ m.
  • Example 10 It is basically the same as Example 10, except that the diameter of the cellulose nanofibers is 12.0 nm, the length is 7.0 ⁇ m, and the carboxyl content is 1.0 mmol/g.
  • Example 10 It is basically the same as Example 10, except that the diameter of the cellulose nanofibers is 20.0 nm, the length is 10.0 ⁇ m, and the carboxyl content is 1.5 mmol/g.
  • Example 12 It is basically the same as Example 12, except that graphene is used instead of carbon nanotubes, and the diameter of the graphene sheet is 3 ⁇ m and the thickness is 0.8 nm.
  • Example 12 It is basically the same as Example 12, except that the porous polypropylene membrane is replaced by a polyvinylidene fluoride membrane with an average pore size of 100 nm.
  • Example 2 It is basically the same as Example 1, except that the concentration of the cellulose nanofibers is 0.07692 wt.%, that is, the concentration ratio of the carbon nanotubes to the cellulose nanofibers is 3.9:1.
  • Example 2 It is basically the same as Example 1, except that the concentration of the cellulose nanofibers is 0.03704 wt.%, that is, the concentration ratio of the carbon nanotubes to the cellulose nanofibers is 8.1:1.
  • the method is basically the same as Example 2, except that the concentration of carbon nanotubes in the coating solution is 0.29 wt.%, and the concentration of cellulose nanofibers is 0.0483 wt.%.
  • the method is basically the same as Example 2, except that the concentration of carbon nanotubes in the coating solution is 1.01 wt.%, and the concentration of cellulose nanofibers is 0.1683 wt.%.
  • the method is basically the same as Example 4, except that the concentration of sodium dodecylbenzene sulfonate in the coating liquid is 0.01 wt.%.
  • the method is basically the same as Example 4, except that the concentration of sodium dodecylbenzene sulfonate in the coating liquid is 0.21 wt.%.
  • Example 6 It is basically the same as Example 6, except that the average pore size of the porous polypropylene membrane is 49 nm.
  • Example 6 It is basically the same as Example 6, except that the average pore size of the porous polypropylene membrane is 151 nm.
  • Example 8 It is basically the same as Example 8, except that the diameter of the carbon nanotube is 1 nm and the length is 0.5 ⁇ m.
  • Example 8 It is basically the same as Example 8, except that the diameter of the carbon nanotube is 11 nm and the length is 5.5 ⁇ m.
  • Example 10 It is basically the same as Example 10, except that the diameter of the cellulose nanofibers is 4.0 nm, the length is 4.0 ⁇ m, and the carboxyl content is 0.4 mmol/g.
  • Example 10 It is basically the same as Example 10, except that the diameter of the cellulose nanofibers is 21.0 nm, the length is 11.0 ⁇ m, and the carboxyl content is 1.6 mmol/g.
  • the method is basically the same as Example 1, except that the polypropylene film is not subjected to corona treatment.
  • the method is basically the same as Example 1, except that: the preparation step (2) of the intermediate transition layer is omitted; before the preparation of the conductive copper layer and the protective layer, a composite copper current collector semi-finished product is first prepared by a conventional magnetron sputtering (physical vapor deposition) process; the basic process of magnetron sputtering is to use copper metal as a target material and argon gas as a gas source; the pressure in the chamber during operation is (1.0 ⁇ 10 -6 ) torr, the power supply of the DC magnetron sputtering is 200 W, and a 90 nm thick copper layer is plated on the polypropylene film by magnetron sputtering in a vacuum sputtering chamber.
  • a conventional magnetron sputtering physical vapor deposition
  • the semi-finished composite copper current collector sample prepared above was placed in an argon ion polisher (Fischione 1061) and cut using an argon ion beam ( ⁇ 1 mm). After cutting, the sample was sprayed with gold to prepare a cross-sectional sample.
  • the prepared cross-sectional sample was then placed in a field emission electron microscope (Zeiss Gemini Sigma 300 VP SEM), magnified 50,000 times, and after adjusting the clarity, the cross-sectional morphology of the sample was observed and a photo was output; finally, the thickness of the intermediate transition layer in the cross-sectional morphology photo was marked using the measurement software provided by the electron microscope, thereby obtaining the thickness data of the intermediate transition layer.
  • a layer of Permacel P-94 double-sided adhesive is bonded to a 1mm thick aluminum foil, a composite copper current collector semi-finished product or composite copper current collector is bonded on the double-sided adhesive, and a layer of ethylene acrylic acid copolymer film (DuPont Nurcel0903, thickness 50 ⁇ m) is covered on the sample, and then hot-pressed at 1.3 ⁇ 105N/ m2 and 120°C for 10s, cooled to room temperature, and cut into 150mm ⁇ 15mm strips. Finally, the ethylene acrylic acid copolymer film of the sample strip is fixed to the upper fixture of the tensile machine, and the rest is fixed to the lower fixture. After fixing, the two are peeled at an angle of 180° and a speed of 100mm/min. The peeling force is tested, that is, the bonding force between the intermediate transition layer and the conductive copper layer or the bonding force between the intermediate transition layer and the polymer substrate is obtained.
  • the composite copper current collector is placed in a surface quality detection system (micro-vision charge coupled device CCD), the surface is scanned, and then the optical signal is converted into an electrical signal and transmitted to a computer.
  • CCD surface quality detection system
  • the number of surface holes with a pore size less than 100 ⁇ m per unit area of the composite copper current collector is counted (it is generally required that the finished product should not have holes larger than 100 ⁇ m), and the number of holes per unit area can be obtained.
  • the flat composite copper current collector semi-finished product and the composite copper current collector sample are placed on a sample table, and the square resistance of the sample is tested using a four-probe square resistance meter.
  • Example 1 By comparing Example 1 with Comparative Example 13, it can be seen that when the polypropylene film is not subjected to corona treatment, the adhesion between the polymer substrate and the intermediate transition layer, as well as the adhesion between the intermediate transition layer and the copper layer are significantly reduced; by comparing Example 1 with Comparative Example 14, it can be seen that by replacing the coating process proposed in the present application with the magnetron sputtering process, the number of holes in the prepared composite copper current collector is significantly increased, indicating that compared with the conventional physical vapor deposition process for preparing the composite copper current collector, the method provided in the present application can effectively reduce hole defects, thereby improving the performance of the composite copper current collector.

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Abstract

本申请提供一种复合铜集流体及其制备方法、极片、二次电池和用电装置，复合铜集流体包括：聚合物基材层；设置于聚合物基材层的至少一侧表面上的中间过渡层，其中，中间过渡层中包含碳纳米材料和纤维素纳米纤维；和设置于中间过渡层的相对远离聚合物基材层一侧的表面上的铜层。

Description

复合铜集流体及其制备方法、极片、二次电池和用电装置
相关申请
本申请要求2022年11月02日申请的，申请号为2022113613889，名称为“复合铜集流体及其制备方法、极片、二次电池和用电装置”的中国专利申请的优先权，在此将其全文引入作为参考。
技术领域
本申请涉及电化学技术领域，特别是涉及一种复合铜集流体及其制备方法、极片、二次电池和用电装置。
背景技术
目前，基于高分子聚合物膜的复合铜集流体得到新能源行业的广泛关注和应用。常规的复合铜集流体通常包括高分子聚合物膜层，以及通过物理气相沉积(PVD)等方法在高分子聚合物膜层上形成的金属铜层。相应的制备过程通常包括：(1)采用物理气相沉积(磁控溅射或者蒸镀)的方法在高分子聚合物膜上沉积一层铜，制备出具备一定导电能力的复合铜集流体半成品；(2)利用电镀对复合铜集流体半成品做进一步处理，从而制备出复合铜集流体。相比传统的集流体(铜箔)，基于高分子聚合物膜的复合铜集流体具备成本低、质量轻、内部绝缘性好等特点。这些特点使得复合集铜流体在二次电池中应用时能够降低二次电池的成本、并提升电池的能量密度及安全性。然而，常规复合铜集流体的制备过程中所涉及的物理气相沉积工艺存在能耗高的问题，高能耗会带来复合铜集流体成本的提高。
发明内容
基于此，本申请提供一种复合铜集流体及其制备方法、极片、二次电池和用电装置，可以降低复合铜集流体的制备能耗，从而降低成本。
本申请的第一方面提供了一种复合铜集流体，包括：
聚合物基材层；
设置于所述聚合物基材层的至少一侧表面上的中间过渡层，其中，所述中间过渡层中 包含碳纳米材料和纤维素纳米纤维；和
设置于所述中间过渡层的相对远离所述聚合物基材层一侧的表面上的铜层。
在本申请的一些实施方式中，所述复合铜集流体满足如下条件中的至少一者：
(1)所述碳纳米材料在所述中间过渡层中的质量占比为52％至88％；
(2)所述纤维素纳米纤维在所述中间过渡层中的质量占比为7％至20％；
(3)所述碳纳米材料包括碳纳米管、石墨烯和碳纳米纤维中的一种或多种，可选地，所述碳纳米管为单壁碳纳米管，
进一步可选地，所述单壁碳纳米管的直径为2nm至10nm，长度为1μm至5μm。
在本申请的一些实施方式中，所述复合铜集流体满足如下条件中的至少一者：
(1)所述石墨烯的片径为0.5μm至5μm，厚度为0.8nm至1.2nm；
(2)所述碳纳米纤维的直径为50nm至200nm，长度为1μm至15μm；
(3)所述纤维素纳米纤维的直径为5nm至20nm，长度为5μm至10μm，羧基含量为0.5mmol/g至1.5mmol/g。
在本申请的一些实施方式中，所述复合铜集流体满足如下条件中的至少一者：
(1)所述聚合物基材层的厚度为2μm至20μm；
(2)所述中间过渡层的厚度为500nm以上，可选为500nm至1500nm；
(3)所述铜层的厚度为500nm至2000nm，可选为700nm至1200nm。
在本申请的一些实施方式中，所述复合铜集流体满足如下条件中的至少一者：
(1)所述聚合物基材层中包含至少一个孔洞，可选地，所述孔洞的平均孔径为50nm至150nm；
(2)所述聚合物基材包括聚丙烯、聚乙烯、聚对苯二甲酸乙二醇酯、聚对苯二甲酸丁二醇酯、聚萘二甲酸乙二醇酯、聚酰亚胺、聚丙乙烯、聚氯乙烯、聚偏氟乙烯、聚四氟乙烯、聚苯硫醚、聚苯醚、聚苯乙烯、聚酰胺及上述聚合物的衍生物中的一种或多种。
在本申请的一些实施方式中，所述复合铜集流体还包括保护层，所述保护层设置于所述铜层的相对远离所述中间过渡层一侧的表面上，可选地，所述保护层的厚度为10nm至150nm。
在本申请的一些实施方式中，所述复合铜集流体满足如下条件中的至少一者：
(1)所述保护层的厚度为20nm至100nm，可选地，所述保护层的厚度不高于所述金属层厚度的十分之一；
(2)保护层的材料包括镍、铬、镍基合金、铜基合金、氧化铜、氧化铝、氧化镍、氧化铬、氧化钴、石墨、炭黑、乙炔黑、科琴黑、碳纳米量子点、碳纳米管、碳纳米纤维 和石墨烯中的一种或多种。
本申请的第二方面提供了一种用于制备复合铜集流体的方法，包括：
在所述聚合物基材层的至少一侧的表面上涂覆过渡液，形成中间过渡层，得到复合膜，其中，所述过渡液中包含碳纳米材料和纤维素纳米纤维；和
对所述复合膜做电镀处理，在所述中间过渡层的远离所述聚合物基材层一侧的表面上沉积铜层，得到复合铜集流体。
在本申请的一些实施方式中，所述方法满足如下条件中的至少一者：
(1)所述过渡液中所述碳纳米材料的质量百分浓度为0.30wt.％至1.0wt.％；
(2)所述过渡液中所述碳纳米材料的质量百分浓度与所述纤维素纳米纤维的质量百分浓度之比为4:1至8:1；
(3)所述过渡液中还包含表面活性剂，可选地，所述表面活性剂的质量百分浓度为0.02wt.％至0.2wt.％；
可选地，所述表面活性剂包括十二烷基苯磺酸钠、十二烷基硫酸钠、十六烷基三甲基溴化铵、十二烷基磺酸钠、聚山梨醇酯-20、聚山梨酯-80、聚氧乙烯单月桂酸酯、聚氧乙烯单月桂酸酯、月桂基磺化琥珀酸单酯二钠、单十二烷基磷酸酯钾和月桂酰胺丙基二甲胺乙内酯中的一种或多种；
(4)所述过渡液的涂覆厚度为80μm至200μm。
在本申请的一些实施方式中，在所述聚合物基材层至少一侧的表面上涂覆过渡液之前，还包括：
对聚合物基材膜的表面做电晕处理，得到所述聚合物基材层，
可选地，所述电晕处理的功率为10kW至30kW；
可选地，所述电晕处理的线速度为50m/min至200m/min。
在本申请的一些实施方式中，在所述中间过渡层的远离所述聚合物基材层一侧的表面上沉积铜层之后，还包括：
在所述铜层的远离所述中间过渡层一侧的表面上制备保护层，
可选地，制备所述保护层的方法包括物理气相沉积、化学气相沉积、原位成型法和涂布法中的一种或多种。
本申请的第三方面提供了一种极片，包括本申请第一方面的复合铜集流体或根据本申请第二方面的方法制备的复合铜集流体。
在本申请的一些实施方式中，所述极片包括正极极片和/或负极极片。
本申请的第四方面提供了一种二次电池，包括本申请第三方面的极片。
本申请的第五方面提供了一种用电装置，包括本申请第四方面的二次电池。
本申请的用电装置包括本申请提供的二次电池，因而至少具有与所述二次电池相同的优势。
本申请的一个或多个实施例的细节在下面的附图和描述中提出。本申请的其它特征、目的和优点将从说明书、附图以及权利要求书变得明显。
附图说明
为了更清楚地说明本申请实施例或传统技术中的技术方案，下面将对实施例或传统技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据公开的附图获得其他的附图。
图1为本申请一实施方式的复合铜集流体的结构示意图。
图2为本申请另一实施方式的复合铜集流体的结构示意图。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
为了简便，本申请仅明确地公开了一些数值范围。然而，任意下限可以与任何上限组合形成未明确记载的范围；以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，尽管未明确记载，但是范围端点间的每个点或单个数值都包含在该范围内。因而，每个点或单个数值可以作为自身的下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
除非另有定义，本文所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同。本文中在本申请的说明书中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请。需要说明的是，除非另有说明，本文所使用的术语“和/或”包括一个或多个相关的所列项目的任意的和所有的组合，“以上”、“以下”为包含本数，“一种或多种”中的“多种”的含义是两种以上。
除非另有说明，本申请中使用的术语具有本领域技术人员通常所理解的公知含义。除 非另有说明，本申请中提到的各参数的数值可以用本领域常用的各种测量方法进行测量(例如，可以按照在本申请的实施例中给出的方法进行测试)。
术语“中的至少一者”、“中的至少一个”、“中的至少一种”或其他相似术语所连接的项目的列表可意味着所列项目的任何组合。例如，如果列出项目A及B，那么短语“A及B中的至少一者”意味着仅A；仅B；或A及B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的至少一者”意味着仅A；或仅B；仅C；A及B(排除C)；A及C(排除B)；B及C(排除A)；或A、B及C的全部。项目A可包含单个组分或多个组分。项目B可包含单个组分或多个组分。项目C可包含单个组分或多个组分。
本申请的上述申请内容并不意欲描述本申请中的每个公开的实施方式或每种实现方式。如下描述更具体地举例说明示例性实施方式。在整篇申请中的多处，通过一系列实施例提供了指导，这些实施例可以以各种组合形式使用。在各个实例中，列举仅作为代表性组，不应解释为穷举。
发明人在研究过程中发现意外发现，在目前的常规复合铜集流体的制备过程中，通过物理气相沉积法在高分子聚合物膜层上制备形成的复合铜集流体半成品表面会存在孔洞缺陷，由于孔洞缺陷处不导电，在后续的电镀过程中导致铜原子无法在孔洞缺陷处沉积，从而使制备的复合铜集流体成品也存在孔洞缺陷，影响复合铜集流体的性能及应用。为解决前述技术问题，发明人从减少和消除孔洞缺陷的角度出发，提出了本申请如下的技术方案。
本申请实施方式的第一方面提供了一种用于制备复合铜集流体的方法，可以包括如下步骤：
S10、在所述聚合物基材层的至少一侧的表面上涂覆过渡液，形成中间过渡层，得到复合膜，其中，所述过渡液中包含碳纳米材料和纤维素纳米纤维；
S20、对所述复合膜做电镀处理，在所述中间过渡层的远离所述聚合物基材层一侧的表面上沉积铜层，得到复合铜集流体。
本申请提供的方法首先采用表面涂覆的工艺在聚合物基材层的表面上涂覆一层包含碳纳米材料和纤维素纳米纤维的中间过渡层，然后利用电镀处理在中间过渡层的表面上沉积铜层，得到复合铜集流体。由此，在复合铜集流体的制备过程中，可实现利用表面涂覆的工艺代替常规的物理气相沉积工艺，继而可规避物理气相沉积法在制备复合铜集流体时造成的表面孔洞缺陷等问题，减少或消除表面孔洞缺陷，提升复合铜集流体的性能。此外，通过利用表面涂覆工艺代替物理气相沉积工艺，还可降低因物理气相沉积而增加的制备能耗，从而有利于降低成本。
可以理解的是，由于过渡液中包含碳纳米材料和纤维素纳米纤维，因此形成的中间过渡层中也包含碳纳米材料和纤维素纳米纤维，其中，碳纳米材料可提供导电性，有利于铜层在中间过渡层上的沉积；而纤维素纳米纤维可提供粘结性，增强中间过渡层与聚合物基材层的粘结力。
在一些实施方式中，步骤S10可以包括涂覆和烘干两个步骤，即：
S100、将过渡液涂覆在聚合物基材层的至少一侧的表面上，形成过渡液涂层；
S110、对表面涂布有过渡液涂层的聚合物基材层做烘干处理。
在一些实施例中，将过渡液涂覆在聚合物基材层上的涂覆方式不做特别的限定，可根据实际需求进行选择。例如，涂覆方式可以为狭缝挤出涂布、刮刀涂布、挤压涂布等中的一种或多种。
作为烘干处理的一个非限制性示例，可以将表面涂布有过渡液涂层的聚合物基材层置于热风烘箱内，于70℃至100℃下进行烘干。
在一些实施方式中，所述过渡液中所述碳纳米材料的质量百分浓度为0.30wt.％至1.0wt.％。碳纳米材料的质量百分浓度在合适范围内，可使中间过渡层具备足够的导电性，从而有利于铜层的沉积。
在一些实施方式中，所述过渡液中所述碳纳米材料的质量百分浓度与所述纤维素纳米纤维的质量百分浓度之比为4:1至8:1。碳纳米材料的质量百分浓度与纤维素纳米纤维的质量百分浓度之比在合适范围内，既可使中间过渡层具备足够的导电性，也可为中间过渡层提供足够的粘结性能。若二者的比例较低，则碳纳米材料含量过低，可能会使导电性变差；若二者的比例较高，则碳纳米材料含量过高，易发生团聚，导致导电性变差。
在一些实施方式中，所述过渡液中还包含表面活性剂，表面活性剂的种类不做特别的限定，可根据实际需求进行选择。例如，所述表面活性剂可以包括十二烷基苯磺酸钠、十二烷基硫酸钠、十六烷基三甲基溴化铵、十二烷基磺酸钠、聚山梨醇酯-20、聚山梨酯-80、聚氧乙烯单月桂酸酯、聚氧乙烯单月桂酸酯、月桂基磺化琥珀酸单酯二钠、单十二烷基磷酸酯钾和月桂酰胺丙基二甲胺乙内酯中的一种或多种。
在一些实施例中，所述表面活性剂的质量百分浓度为0.02wt.％至0.2wt.％。表面活性剂的质量百分浓度在合适范围内，有利于促进碳纳米材料在过渡液中的分散性。
在一些实施例中，所述聚合物基材的种类不做特别的限定，可根据实际需求进行选择。例如，聚合物基材可以包括聚丙烯(PP)、聚乙烯(PE)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚萘二甲酸乙二醇酯(PEN)、聚丙乙烯、聚氯乙烯(PVC)、聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚苯硫醚(PPS)、聚苯醚(PPO)、聚苯乙烯 (PS)、聚酰亚胺(PI)等材料以及它们的衍生物中的一种或多种。可选地，聚合物基材为多孔结构，平均孔径为50nm至150nm。当孔径过小或者过大时，易导致聚合物基材层与中间过渡层的粘结力降低。
在一些实施例中，聚合物基材层可通过熔融-挤出-双向拉伸法制备获得。
在一些实施方式中，所述过渡液的涂覆厚度为80μm至200μm。若涂覆厚度较低，则中间过渡层较薄，易使导电性较差，导致后续电镀的效果较差；若涂覆厚度较高，则中间过渡层较厚，会增加复合铜集流体的厚度，不利于复合铜集流体在二次电池中的应用。
在一些实施方式中，步骤S20中电镀处理的电镀液中可以包括硫酸铜、硫酸、浓盐酸、电解液添加剂以及进行电镀需要的其他物质等。
在一些实施例中，硫酸铜的浓度可以为100g/L至180g/L。例如，硫酸铜的浓度可以为110g/L，120g/L，130g/L，140g/L，150g/L，160g/L，170g/L或处于以上任何数值所组成的范围内。
在一些实施例中，硫酸的浓度可以为60g/L至120g/L。例如，硫酸的浓度可以为70g/L，80g/L，90g/L，100g/L，110g/L或处于以上任何数值所组成的范围内。
在一些实施例中，浓盐酸的浓度可以为60mg/L至100mg/L。例如，浓盐酸的浓度可以为70g/L，80g/L，90g/L或处于以上任何数值所组成的范围内。
在一些实施例中，电解液添加剂的浓度可以为3mg/L至10mg/L。例如，电解液添加剂的浓度可以为4mg/L，5mg/L，6mg/L，7mg/L，8mg/L，9mg/L或处于以上任何数值所组成的范围内。
在一些实施例中，电解液添加剂的种类不做特别的限定，可根据实际需求进行选择。例如，电解液添加剂可以为络合剂、促进剂和抑制剂中的一种或多种。可选地，络合剂可以包括酒石酸钾钠、柠檬酸钠、乙二胺四乙酸二钠及三乙醇胺中的一种或多种；促进剂可以包括聚二硫二丙烷磺酸钠和3-巯基-1-丙烷磺酸钠中的至少一种；抑制剂可以为聚乙二醇。
在一些实施例中，进行上述电镀处理时，电镀液的温度可控制为25℃，平均阴极电流密度可控制为1A/dm 2至3A/dm 2。
在一些实施方式中，在步骤S10之前，还包括如下步骤：
S30、对聚合物基材膜的表面做电晕处理，得到所述聚合物基材层。
步骤S30中对聚合物基材膜的表面做电晕处理有利于提高膜表面张力，促进聚合物基材层与中间过渡层的粘结力。
在一些实施方式中，所述电晕处理的功率可以为10kW至30kW，电流可以为4A至10A。
在一些实施方式中，所述电晕处理的线速度可以为50m/min至200m/min。
上述电晕处理的功率等参数控制在合适范围内，有利于进一步提高膜表面张力，促进聚合物基材层与中间过渡层的粘结力。
在一些实施方式中，在步骤S20之后，还包括如下步骤：
S40、在所述铜层的远离所述中间过渡层一侧的表面上制备保护层。
步骤S40中保护层的制备有利于防止导电层被化学腐蚀或物理损坏。
在一些实施方式中，制备所述保护层的方法包括物理气相沉积、化学气相沉积、原位成型法和涂布法中的一种或多种。其中，物理气相沉积优选真空蒸镀及磁控溅射；化学气相沉积优选常压化学气相沉积及等离子体增强化学气相沉积；原位成型法优选在金属层表面原位形成金属氧化物钝化层的方法；涂布法优选模头涂布、刮刀涂布和挤压涂布。
作为制备保护层的一个非限制性示例，可将步骤S20中电镀处理后形成的复合膜层在纯水槽中进行清洗，然后在钝化槽内进行钝化制备保护层，钝化温度为可以为25℃，钝化液可以为5g/L的重铬酸钾或铬酐的水溶液，最后再通过纯水槽进行清洗。清洗完成后，可在70℃至90℃烘箱内进行干燥，得到含保护层的复合铜集流体。
本申请实施方式的第二方面提供了一种复合铜集流体，可根据本申请实施方式第一方面的方法制备而得，如附图1所示，复合铜集流体包括聚合物基材层1，设置于所述聚合物基材层1的至少一侧表面上的中间过渡层2，和设置于所述中间过渡层的相对远离所述聚合物基材层一侧的表面上的铜层3；其中，所述中间过渡层2中包含碳纳米材料和纤维素纳米纤维。
本申请提供的复合铜集流体在聚合物基材层与铜层之间设置有中间过渡层，中间过渡层可将聚合物基材层与铜层隔开，减少或消除聚合物基材层与铜层直接接触复合时形成的孔洞缺陷，提升复合铜集流体的性能。其中，中间过渡层中包含的碳纳米材料可提供导电性，增强复合铜集流体的导电性能；而中间过渡层中包含的纤维素纳米纤维则可提供粘结性，增强中间过渡层与聚合物基材层间的粘结力，提升复合铜集流体的结构稳定性。
在一些实施方式中，所述碳纳米材料在所述中间过渡层中的质量占比为52％至88％。碳纳米材料在中间过渡层中的质量占比在合适范围内，可有效提升复合铜集流体的导电性能。
在一些实施方式中，所述纤维素纳米纤维在所述中间过渡层中的质量占比为7％至20％。纤维素纳米纤维在中间过渡层中的质量占比在合适范围内，可保证中间过渡层与聚合物基材层间具备足够的粘结力，使复合铜集流体具备较高的结构稳定性。
在一些实施方式中，碳纳米材料的种类不做具体的限定，可根据实际需求进行选择。 例如，所述碳纳米材料包括碳纳米管、石墨烯和碳纳米纤维中的一种或多种。
在一些实施方式中，所述碳纳米管为单壁碳纳米管，可选地，所述单壁碳纳米管的直径为2nm至10nm，长度为1μm至5μm。
在一些实施方式中，所述石墨烯的片径为0.5μm至5μm，厚度为0.8nm至1.2nm。
在一些实施方式中，所述碳纳米纤维的直径为50nm至200nm，长度1μm至15μm。
碳纳米材料的尺寸控制在相应的合适范围内，有利于提升中间过渡层的导电性。若尺寸较小，则导电性会较差；若尺寸较大，则中间过渡层的均匀性和导电性会变差。
在一些实施方式中，所述纤维素纳米纤维的直径为5nm至20nm，长度为5μm至10μm，羧基含量为0.5mmol/g至1.5mmol/g。若纤维素纳米纤维的尺寸较小，则不易有效地粘结碳纳米管；若纤维素纳米纤维的尺寸较大，则中间过渡层的均匀性和导电性会变差。若纤维素纳米纤维的羧基含量较低，则纤维素纳米纤维的分散性较差，易导致过渡液的涂覆效果变差；若羧基含量较高，则不易有效地粘结碳纳米管，导致中间过渡层的稳定性变差。
在一些实施方式中，所述聚合物基材层的厚度为2μm至20μm。聚合物基材层的厚度控制在合适范围内，在满足复合集铜流体应用要求的同时，还可兼顾制备工艺的难度和成本的高低。
在一些实施方式中，所述聚合物基材层中包含至少一个孔洞，可选地，所述孔洞的平均孔径为50nm至150nm。聚合物基材层中的孔洞可进一步提升中间过渡层与聚合物基材层之间的粘结力。当孔径较小或者较大时，易导致聚合物基材层与中间过渡层的粘结力降低。
在一些实施方式中，聚合物基材的种类没有特别的限定，可根据实际需求进行选择。例如，所述聚合物基材可以包括聚丙烯、聚乙烯、聚对苯二甲酸乙二醇酯、聚对苯二甲酸丁二醇酯、聚萘二甲酸乙二醇酯、聚酰亚胺、聚丙乙烯、聚氯乙烯、聚偏氟乙烯、聚四氟乙烯、聚苯硫醚、聚苯醚、聚苯乙烯、聚酰胺及上述聚合物的衍生物中的一种或多种。
在一些实施方式中，所述中间过渡层的厚度为500nm以上，可选为500nm至1500nm。中间过渡层可赋予聚合物基材层一定的导电性，从而实现电镀制备铜层的目的。考虑到中间过渡层的导电要求，其厚度应不低于500nm；进一步考虑到电池应用端对复合铜集流体轻薄的要求，中间过渡层的厚度可选为500nm至1500nm。
可以理解的是，中间过渡层可设置于聚合物基材层一侧的表面上，也可同时设置于聚合物基材层相对两侧的表面上；当同时设置时，两侧的中间过渡层的厚度可以相同，也可以不同，具体的设置方式可根据实际需求进行选择。
在一些实施方式中，所述铜层的厚度为500nm至2000nm，可选为700nm至1200nm。 本申请实施方式中，铜层可起到导电的作用。
可以理解的是，铜层可设置于位于聚合物基材层一侧的中间过渡层的表面上，也可同时设置于位于聚合物基材层两侧的中间过渡层的表面上；当同时设置时，两侧的铜层的厚度可以相同，也可以不同，具体的设置方式可根据实际需求进行选择。
在一些实施方式中，如附图2所示，所述复合铜集流体还可以包括保护层4，所述保护层4设置于所述铜层3相对远离所述中间过渡层2一侧的表面上。
在一些实施例中，所述保护层的厚度为10nm至150nm，且所述保护层的厚度不超过金属层厚度的十分之一。可选地，所述保护层的厚度为20nm至100nm。
保护层主要为防止导电层被化学腐蚀或物理损坏，保护层的厚度在合适范围内，在起到较好的保护效果的同时，还不会影响导电层的导电性。若保护层太薄，则易使保护效果不明显；若保护层太厚，则可能会影响导电性。
在一些实施方式中，保护层的材料包括镍、铬、镍基合金、铜基合金、氧化铜、氧化铝、氧化镍、氧化铬、氧化钴、石墨、炭黑、乙炔黑、科琴黑、碳纳米量子点、碳纳米管、碳纳米纤维和石墨烯中的一种或多种。
可以理解的是，保护层可设置于位于聚合物基材层一侧的铜层的表面上，也可同时设置于位于聚合物基材层两侧的铜层的表面上；当同时设置时，两侧保护层的材料、厚度需一致。
本申请实施方式的第三方面提供了一种极片，包括本申请第一方面的复合铜集流体或通过本申请第二方面的方法制得的复合铜集流体。
在一些实施方式中，所述极片包括正极极片和/或负极极片。
本申请实施方式的第四方面提供了一种二次电池，包括本申请第三方面的极片。
在一些实施方式中，二次电池包括正极极片、负极极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
本申请实施方式的第五方面提供了一种用电装置，包括本申请第四方面的二次电池。所述二次电池可以用作所述装置的电源，也可以用作所述装置的能量存储单元。所述装置可以但不限于是移动设备、电动车辆、电气列车、船舶及卫星、储能系统等。例如，可以为笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、 备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池等。
实施例
以下为具体实施例，下述实施例更具体地描述了本申请公开的内容，这些实施例仅仅用于阐述性说明，因为在本申请公开内容的范围内进行各种修改和变化对本领域技术人员来说是明显的。除非另有声明，以下实施例中所报道的所有份、百分比、和比值都是基于重量计，而且实施例中使用的所有试剂都可商购获得或是按照常规方法进行合成获得，并且可直接使用而无需进一步处理，以及实施例中使用的仪器均可商购获得。
实施例1
(1)聚合物基材的电晕处理
选取厚度为3μm、平均孔径为50nm的多孔聚丙烯膜为基膜，置于电晕处理装置中，电晕处理的功率为10kW，电流为4A，处理线速度为50m/min，即得到电晕处理的聚丙烯膜。
(2)中间过渡层的制备
称取一定量的单壁碳纳米管(直径为2nm，长度为1μm)、纤维素纳米纤维(2wt.％水凝胶，所含纤维直径为5.0nm，长度为5.0μm，羧基含量为0.5mmol/g)、十二烷基苯磺酸钠加入到纯水中，先搅拌10min，然后超声分散60min(超声功率为600W，超声频率为40kHz)，得到0.30wt.％的碳纳米管、0.075wt.％的纤维素纳米纤维、0.02wt.％的十二烷基苯磺酸钠的均匀水分散液，即碳纳米管与纤维素纳米纤维的浓度之比为4:1。
以电晕处理的聚丙烯膜为基材，置于狭缝挤出式模头正下方2mm处，将上述制备好的涂覆液从狭缝挤出式模头中挤出，均匀涂覆在聚丙烯膜上，涂覆厚度为150μm，涂覆完成后，进入到100℃热风箱内烘干，烘干完成后，对基膜的另外一面重复进行上述的涂布-烘干处理，即得到表面含有中间过渡层的聚丙烯膜(复合铜集流体半成品)。
(3)导电铜层及保护层的制备
将上述制备的表面含有中间过渡层的聚丙烯膜置于电镀装置内进行电镀处理，电镀分为如下三个过程：
电镀：电镀液为150g/L硫酸铜、120g/L硫酸、60mg/L浓盐酸、7mL/L的电解液添加剂(重庆立道公司的LD-5120M产品)，电镀液温度为25℃，平均阴极电流密度为2A/dm 2。
钝化：电镀结束后，将镀好的薄膜置于纯水清洗槽中进行清洗，然后在钝化槽内进行钝化，制备表面保护层，钝化液为5g/L重铬酸钾的水溶液，温度为25℃，最后再通过纯水槽进行清洗。
干燥：在烘箱温度为70℃的条件下对清洗后的复合膜进行干燥，制备出镀层厚度为1μm的电镀导电铜层及保护层，即得到复合铜集流体。
实施例2
与实施例1基本相同，区别在于：涂覆液中纤维素纳米纤维的浓度为0.050wt.％，即碳纳米管与纤维素纳米纤维的浓度之比为6:1。
实施例3
与实施例1基本相同，区别在于：涂覆液中纤维素纳米纤维的浓度为0.0375wt.％，即碳纳米管与纤维素纳米纤维的浓度之比为8:1。
实施例4
与实施例2基本相同，区别在于：涂覆液中碳纳米管的浓度为0.60wt.％，纤维素纳米纤维的浓度为0.10wt.％。
实施例5
与实施例2基本相同，区别在于：涂覆液中碳纳米管的浓度为1.00wt.％，纤维素纳米纤维的浓度为0.1667wt.％。
实施例6
与实施例4基本相同，区别在于：涂覆液中十二烷基苯磺酸钠的浓度为0.1wt.％。
实施例7
与实施例4基本相同，区别在于：涂覆液中十二烷基苯磺酸钠的浓度为0.2wt.％。
实施例8
与实施例6基本相同，区别在于：多孔聚丙烯膜的平均孔径为100nm。
实施例9
与实施例6基本相同，区别在于：多孔聚丙烯膜的平均孔径为150nm。
实施例10
与实施例8基本相同，区别在于：碳纳米管的直径为6nm，长度为3μm。
实施例11
与实施例8基本相同，区别在于：碳纳米管的直径为10nm，长度为5μm。
实施例12
与实施例10基本相同，区别在于：纤维素纳米纤维的直径为12.0nm，长度为7.0μm，羧基含量为1.0mmol/g。
实施例13
与实施例10基本相同，区别在于：纤维素纳米纤维的直径为20.0nm，长度为10.0μm， 羧基含量为1.5mmol/g。
实施例14
与实施例12基本相同，区别在于：用石墨烯代替碳纳米管，石墨烯的片径为3μm、厚度0.8nm。
实施例15
与实施例12基本相同，区别在于：将多孔聚丙烯膜替换为平均孔径为100nm的聚偏二氟乙烯膜。
对比例1
与实施例1基本相同，区别在于：纤维素纳米纤维的浓度为0.07692wt.％，即碳纳米管与纤维素纳米纤维的浓度之比为3.9:1。
对比例2
与实施例1基本相同，区别在于：纤维素纳米纤维的浓度为0.03704wt.％，即碳纳米管与纤维素纳米纤维的浓度之比为8.1:1。
对比例3
与实施例2基本相同，区别在于：涂覆液中碳纳米管的浓度为0.29wt.％，纤维素纳米纤维的浓度为0.0483wt.％。
对比例4
与实施例2基本相同，区别在于：涂覆液中碳纳米管的浓度为1.01wt.％，纤维素纳米纤维的浓度为0.1683wt.％。
对比例5
与实施例4基本相同，区别在于：涂覆液中十二烷基苯磺酸钠的浓度为0.01wt.％。
对比例6
与实施例4基本相同，区别在于：涂覆液中十二烷基苯磺酸钠的浓度为0.21wt.％。
对比例7
与实施例6基本相同，区别在于：多孔聚丙烯膜的平均孔径为49nm。
对比例8
与实施例6基本相同，区别在于：多孔聚丙烯膜的平均孔径为151nm。
对比例9
与实施例8基本相同，区别在于：碳纳米管的直径为1nm，长度为0.5μm。
对比例10
与实施例8基本相同，区别在于：碳纳米管的直径为11nm，长度为5.5μm。
对比例11
与实施例10基本相同，区别在于：纤维素纳米纤维的直径为4.0nm，长度为4.0μm，羧基含量为0.4mmol/g。
对比例12
与实施例10基本相同，区别在于：纤维素纳米纤维的直径为21.0nm，长度为11.0μm，羧基含量为1.6mmol/g。
对比例13
与实施例1基本相同，区别在于：聚丙烯膜不进行电晕处理。
对比例14
与实施例1基本相同，区别在于：省略中间过渡层的制备步骤(2)，在导电铜层及保护层的制备之前，先以传统的磁控溅射(物理气相沉积)工艺制备复合铜集流体半成品，磁控溅射的基本工艺为以铜金属为靶材，以氩气为气源，工作时舱体内的压力为(1.0×10 -6)torr，直流磁控溅射的电源为200W，在真空溅射舱体内通过磁控溅射的方法在聚丙烯膜上镀一层90nm厚的铜层。
将实施例1至15及对比例1至14制得的复合铜集流体进行相关的性能测试，测试结果如下表1和表2所示；其中，“/”表示不存在该项性能。
测试部分
(1)中间过渡层的厚度
首先，将上述制备的复合铜集流体半成品样品置于氩离子抛光仪(Fischione 1061)中利用氩离子束(～1mm)来切割样品，切割完成后，对样品进行喷金处理，从而制备出断面样品。然后将制备的断面样品置于场发射电镜(Zeiss Gemini Sigma 300 VP SEM)中，放大5万倍，调节清晰后，观察样品的断面形貌并输出照片；最后，利用电镜自带的测量软件，标注出断面形貌照片中中间过渡层的厚度，从而获得中间过渡层的厚度数据。
(2)粘结力测试
在一个1mm厚的铝箔上粘接一层Permacel P-94双面胶，在双面胶的上方粘接复合铜集流体半成品或复合铜集流体，在样品上方覆盖一层乙烯丙烯酸共聚物薄膜(杜邦Nurcel0903，厚度为50μm)，然后在1.3×105N/m 2、120℃下热压10s，冷却至室温，裁成150mm×15mm的小条。最后将样品小条的乙烯丙烯酸共聚物薄膜固定于拉力机的上夹具，其余部分固定在下夹具，固定好后二者以180°的角度、100mm/min的速度进行剥离，测试剥离力，即得到中间过渡层与导电铜层间的粘结力或中间过渡层与聚合物基材间的粘结力。
(3)复合铜集流体单位面积上的孔洞数量
将复合铜集流体置于表面质量检测系统(微觉视电荷耦合器件CCD)中，对表面进行扫描，然后将光信号转换为电信号输送到计算机上，对复合铜集流体单位面积上孔径小于100μm的表面孔洞数进行统计(一般要求成品不能有超过100μm的孔洞)，即可获得单位面积上的孔洞数量。
(4)方阻测试
将平整的复合铜集流体半成品和复合铜集流体样品置于样品台上，利用四探针方阻仪对样品的方阻进行测试。
表1
Figure PCTCN2022132110-appb-000001
表2
Figure PCTCN2022132110-appb-000002
对比实施例1至3及对比例1至2可以看出，当碳纳米材料与纤维素纳米纤维的浓度之比在本申请的保护范围内时，提高二者的浓度之比，中间过渡层的厚度降低、聚合物基材与中间过渡层的粘结力以及中间过渡层与铜层的粘结力均降低；制备的复合铜集流体半成品及复合铜集流体的方阻先降低后升高，兼顾粘结力及方阻的变化，优选的二者浓度之比为6:1。在超出本申请的保护范围之后，复合铜集流体半成品及复合铜集流体的性能会降低。
对比实施例2、4、5及对比例3至4可以看出，当碳纳米材料的浓度在本申请保护范围内时，提高碳纳米材料的浓度，中间过渡层的厚度增加、聚合物基材与中间过渡层的粘 结力以及中间过渡层与铜层的粘结力先升高后降低；制备的复合铜集流体半成品及复合铜集流体的方阻降低，兼顾粘结力及方阻的变化，优选的碳纳米材料的浓度为0.60wt.％。在超出本申请的保护范围之后，复合铜集流体半成品及复合铜集流体的性能会降低。
对比实施例4、6、7及对比例5至6可以看出，当表面活性剂的浓度在本申请保护范围内时，提高表面活性剂的浓度，中间过渡层厚度略有增加、聚合物基材与中间过渡层的粘结力以及中间过渡层与铜层的粘结力先升高后降低；制备的复合铜集流体半成品及复合铜集流体的方阻略有降低，兼顾粘结力及方阻的变化，优选的表面活性剂的浓度为0.10wt.％。在超出本申请的保护范围之后，复合铜集流体半成品及复合铜集流体的性能会降低。
对比实施例6、8、9及对比例7至8可以看出，当聚合物基材层中孔洞的平均孔径在本申请保护范围内时，提高平均孔径，聚合物基材与中间过渡层的粘结力以及中间过渡层与铜层的粘结力先升高后降低，优选的孔洞的平均孔径为100nm。在超出本申请的保护范围之后，复合铜集流体半成品及复合铜集流体的性能会降低。
对比实施例8、10、11以及对比例9至10可以看出，当碳纳米管的尺寸在本申请的保护范围内时，提高碳纳米管的尺寸，中间过渡层的厚度略有提升、聚合物基材与中间过渡层的粘结力以及中间过渡层与铜层的粘结力先升高后降低，优选的碳纳米管的直径为6nm，长度为3μm。在超出本申请的保护范围之后，复合铜集流体半成品及复合铜集流体的性能会降低。
对比实施例10、12、13与对比例11、12可以看出，当纤维素纳米纤维的尺寸及羧基含量在本申请的保护范围内时，提高纤维素纳米纤维的尺寸及羧基含量，中间过渡层的厚度增大、聚合物基材与中间过渡层的粘结力以及中间过渡层与铜层的粘结力先升高后降低，优选的纤维素纳米纤维的直径为12.0nm，长度为7μm，羧基含量为1.0mmol/g。在超出本申请的保护范围之后，复合铜集流体半成品及复合铜集流体的性能会降低。
对比实施例1与对比例13可以看出，聚丙烯膜不进行电晕处理，聚合物基材与中间过渡层的粘结力以及中间过渡层与铜层的粘结力明显降低；对比实施例1与对比例14可以看出，以磁控溅射工艺替代本申请提出的涂覆工艺，制备的复合铜集流体的孔洞数量明显提升，说明与常规的物理气相沉积制备复合铜集流体的工艺相比，本申请提供的方法可有效减少孔洞缺陷，进而提升复合铜集流体的性能。
以上所述实施例的各技术特征可以进行任意的组合，为使描述简洁，未对上述实施例中的各个技术特征所有可能的组合都进行描述，然而，只要这些技术特征的组合不存在矛盾，都应当认为是本说明书记载的范围。
以上所述实施例仅表达了本申请的几种实施方式，其描述较为具体和详细，但并不能 因此而理解为对申请专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本申请构思的前提下，还可以做出若干变形和改进，这些都属于本申请的保护范围。因此，本申请专利的保护范围应以所附权利要求为准。

Claims (15)

  1. 一种复合铜集流体，包括：
    聚合物基材层；
    设置于所述聚合物基材层的至少一侧表面上的中间过渡层，其中，所述中间过渡层中包含碳纳米材料和纤维素纳米纤维；和
    设置于所述中间过渡层的相对远离所述聚合物基材层一侧的表面上的铜层。
  2. 根据权利要求1所述的复合铜集流体，其中，所述复合铜集流体满足如下条件中的至少一者：
    (1)所述碳纳米材料在所述中间过渡层中的质量占比为52％至88％；
    (2)所述纤维素纳米纤维在所述中间过渡层中的质量占比为7％至20％；和
    (3)所述碳纳米材料包括碳纳米管、石墨烯和碳纳米纤维中的一种或多种，可选地，所述碳纳米管为单壁碳纳米管，
    进一步可选地，所述单壁碳纳米管的直径为2nm至10nm，长度为1μm至5μm。
  3. 根据权利要求2所述的复合铜集流体，其中，所述复合铜集流体满足如下条件中的至少一者：
    (1)所述石墨烯的片径为0.5μm至5μm，厚度为0.8nm至1.2nm；
    (2)所述碳纳米纤维的直径为50nm至200nm，长度1μm至15μm；和
    (3)所述纤维素纳米纤维的直径为5nm至20nm，长度为5μm至10μm，羧基含量为0.5mmol/g至1.5mmol/g。
  4. 根据权利要求1至3任一项所述的复合铜集流体，其中，所述复合铜集流体满足如下条件中的至少一者：
    (1)所述聚合物基材层的厚度为2μm至20μm；
    (2)所述中间过渡层的厚度为500nm以上，可选为500nm至1500nm；和
    (3)所述铜层的厚度为500nm至2000nm，可选为700nm至1200nm。
  5. 根据权利要求1至4任一项所述的复合铜集流体，其中，所述复合铜集流体满足如下条件中的至少一者：
    (1)所述聚合物基材层中包含至少一个孔洞，可选地，所述孔洞的平均孔径为50nm至150nm；和
    (2)所述聚合物基材包括聚丙烯、聚乙烯、聚对苯二甲酸乙二醇酯、聚对苯二甲酸丁二醇酯、聚萘二甲酸乙二醇酯、聚酰亚胺、聚丙乙烯、聚氯乙烯、聚偏氟乙烯、聚四氟 乙烯、聚苯硫醚、聚苯醚、聚苯乙烯、聚酰胺及上述聚合物的衍生物中的一种或多种。
  6. 根据权利要求1至5任一项所述的复合铜集流体，其中，所述复合铜集流体还包括保护层，所述保护层设置于所述铜层的相对远离所述中间过渡层一侧的表面上，可选地，所述保护层的厚度为10nm至150nm。
  7. 根据权利要求6所述的复合铜集流体，其中，所述复合铜集流体满足如下条件中的至少一者：
    (1)所述保护层的厚度为20nm至100nm，可选地，所述保护层的厚度不高于所述金属层厚度的十分之一；和
    (2)保护层的材料包括镍、铬、镍基合金、铜基合金、氧化铜、氧化铝、氧化镍、氧化铬、氧化钴、石墨、炭黑、乙炔黑、科琴黑、碳纳米量子点、碳纳米管、碳纳米纤维和石墨烯中的一种或多种。
  8. 一种用于制备复合铜集流体的方法，包括：
    在所述聚合物基材层的至少一侧的表面上涂覆过渡液，形成中间过渡层，得到复合膜，其中，所述过渡液中包含碳纳米材料和纤维素纳米纤维；和
    对所述复合膜做电镀处理，在所述中间过渡层的远离所述聚合物基材层一侧的表面上沉积铜层，得到复合铜集流体。
  9. 根据权利要求8所述的方法，其中，所述方法满足如下条件中的至少一者：
    (1)所述过渡液中所述碳纳米材料的质量百分浓度为0.30wt.％至1.0wt.％；
    (2)所述过渡液中所述碳纳米材料的质量百分浓度与所述纤维素纳米纤维的质量百分浓度之比为4:1至8:1；
    (3)所述过渡液中还包含表面活性剂，可选地，所述表面活性剂的质量百分浓度为0.02wt.％至0.2wt.％；
    可选地，所述表面活性剂包括十二烷基苯磺酸钠、十二烷基硫酸钠、十六烷基三甲基溴化铵、十二烷基磺酸钠、聚山梨醇酯-20、聚山梨酯-80、聚氧乙烯单月桂酸酯、聚氧乙烯单月桂酸酯、月桂基磺化琥珀酸单酯二钠、单十二烷基磷酸酯钾和月桂酰胺丙基二甲胺乙内酯中的一种或多种；和
    (4)所述过渡液的涂覆厚度为80μm至200μm。
  10. 根据权利要求8或9所述的方法，其中，在所述聚合物基材层至少一侧的表面上涂覆过渡液之前，还包括：
    对聚合物基材膜的表面做电晕处理，得到所述聚合物基材层，
    可选地，所述电晕处理的功率为10kW至30kW；
    可选地，所述电晕处理的线速度为50m/min至200m/min。
  11. 根据权利要求8至10任一项所述的方法，其中，在所述中间过渡层的远离所述聚合物基材层一侧的表面上沉积铜层之后，还包括：
    在所述铜层的远离所述中间过渡层一侧的表面上制备保护层，
    可选地，制备所述保护层的方法包括物理气相沉积、化学气相沉积、原位成型法和涂布法中的一种或多种。
  12. 一种极片，包括权利要求1至7任一项所述的复合铜集流体或通过权利要求8至11任一项所述方法制得的复合铜集流体。
  13. 根据权利要求12所述的极片，其中，所述极片包括正极极片和/或负极极片。
  14. 一种二次电池，包括权利要求12或13所述的极片。
  15. 一种用电装置，包括权利要求14所述的二次电池。
PCT/CN2022/132110 2022-11-02 2022-11-16 复合铜集流体及其制备方法、极片、二次电池和用电装置 WO2024092882A1 (zh)

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