WO2024131866A1 - 负极集流体及其制备方法和锂离子电池 - Google Patents

负极集流体及其制备方法和锂离子电池 Download PDF

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WO2024131866A1
WO2024131866A1 PCT/CN2023/140407 CN2023140407W WO2024131866A1 WO 2024131866 A1 WO2024131866 A1 WO 2024131866A1 CN 2023140407 W CN2023140407 W CN 2023140407W WO 2024131866 A1 WO2024131866 A1 WO 2024131866A1
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layer
conductive layer
current collector
negative electrode
electrode current
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PCT/CN2023/140407
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English (en)
French (fr)
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李永伟
孙欣森
公秀凤
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安迈特科技(北京)有限公司
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Publication of WO2024131866A1 publication Critical patent/WO2024131866A1/zh

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    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
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    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
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    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
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    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
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    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/14—Metallic material, boron or silicon
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    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
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    • C23C14/24—Vacuum evaporation
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    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34—Sputtering
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    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34—Sputtering
    • C23C14/35—Sputtering by application of a magnetic field, e.g. magnetron sputtering
    • 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
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H01M4/662—Alloys
    • 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 technical field of current collectors, and in particular to a negative electrode current collector and a preparation method thereof, and a lithium-ion battery.
  • Lithium-ion batteries generally use aluminum as the positive electrode current collector metal material and copper as the negative electrode current collector metal material. This is because the oxidation potential of aluminum is high, and the size of the lattice octahedral voids of aluminum is similar to that of lithium, making it very easy for aluminum to react with lithium to form alloys such as LiAl, Li 3 Al 2 , and Li 4 Al 3 , which not only consumes a large amount of Li + , but also destroys the structure and morphology of aluminum itself. Therefore, aluminum can be used as the current collector of the positive electrode of lithium-ion batteries, but not as the current collector of the negative electrode of lithium-ion batteries. Cu has only a small lithium insertion capacity during the battery charge and discharge process, and maintains the stability of the structure and electrochemical properties, so it can be used as the current collector of the negative electrode of ion batteries.
  • the market demand has put forward higher and higher requirements on the energy density and weight of lithium-ion batteries.
  • Simple copper foil and aluminum foil can no longer meet the market demand, so people have developed composite current collectors.
  • the current composite current collectors generally have the problems of large mass, low mechanical strength, easy detachment of the conductive layer, easy corrosion by the electrolyte, and low conductivity.
  • the purpose of this application is to overcome the problems of the prior art in that the negative electrode current collector has heavy weight, low mechanical strength, easy detachment of the conductive layer, easy corrosion by the electrolyte, and high resistivity, and to provide a negative electrode current collector and a preparation method thereof and a lithium ion battery.
  • the first aspect of the present application provides a negative electrode current collector, which comprises a barrier layer I, a conductive layer I, a polymer layer, a conductive layer II and a barrier layer II in order.
  • the second aspect of the present application provides a method for preparing a negative electrode current collector, the method comprising: first preparing a conductive layer I and a conductive layer II on the upper surface and the lower surface of a polymer layer, respectively, and then preparing a blocking layer I on the conductive layer I, and preparing a blocking layer II on the conductive layer II.
  • the third aspect of the present application provides a lithium-ion battery comprising the negative electrode current collector described in the first aspect of the present application.
  • the negative electrode current collector provided in this application can replace the traditional copper foil as the negative electrode current collector, saving copper resources and costs and improving safety;
  • the negative electrode current collector provided in the present application can reduce the galvanic corrosion tendency and alloying degree of copper and aluminum by providing an intermediate layer I and an intermediate layer II;
  • the negative electrode current collector provided in the present application is provided with barrier layer I and barrier layer II, which can block the formation of Li-Al alloy and improve the conductivity of the negative electrode current collector.
  • FIG1 is a schematic diagram of the first structure of the negative electrode current collector described in the present application.
  • FIG2 is a schematic diagram of a second structure of the negative electrode current collector described in the present application.
  • FIG3 is a schematic diagram of a third structure of the negative electrode current collector described in the present application.
  • FIG. 4 is a cross-sectional TEM image of the negative electrode current collector obtained in Example 2.
  • any values of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values.
  • the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article.
  • the first aspect of the present application provides a negative electrode current collector, as shown in Figure 1, the negative electrode current collector comprises a barrier layer I 4, a conductive layer I 2, a polymer layer 1, a conductive layer II 3 and a barrier layer II 5 in sequence.
  • the barrier layer I 4 and the barrier layer II 5 are continuous and dense thin film structures, which can prevent the conductive materials in the conductive layer I 2 and the conductive layer II 3 from alloying, and can improve the conductivity of the current collector.
  • the material of the barrier layer I and the barrier layer II is different from the material of the conductive layer I and the conductive layer II.
  • the materials of the barrier layer I 4 and the barrier layer II 5 are independently selected from a single metal I or an alloy I; wherein the single metal I is selected from one of aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum and tungsten; preferably, the single metal I is selected from one of aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum and tungsten with a purity of ⁇ 98wt%, preferably a purity of 99-100wt%; wherein the metal in the alloy I is selected from at least one of aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum and tungsten, and the alloy I also includes an optional non-metal, and the non-metal is selected from at least one of carbon, nitrogen and silicon.
  • the alloy I is selected from at least one of copper-aluminum alloy, copper-nickel alloy,
  • the thickness of the blocking layer I 4 and the blocking layer II 5 are each independently selected from 1-1500nm, for example, 1nm, 10nm, 100nm, 500nm, 800nm, 1000nm, 1200nm, 1400nm, 1500nm, or any value between the aforementioned values, preferably 10-1000nm.
  • the function of the barrier layer is to block the exposure of Al at the negative terminal and also to have a conductive function.
  • the barrier layer of the present application is a continuous dense film; the barrier layer cannot be too thin, otherwise it will interdiffusion with the conductive layer in a short period of time (a few days or weeks), thereby exposing Al and losing the original function of the barrier layer; the barrier layer cannot be too thick, otherwise it will increase the process cost, material utilization efficiency, etc. Therefore, the thickness of the barrier layer is preferably 10-1000nm, more preferably 30nm-800nm.
  • the bonding force between the barrier layer I 4 and the conductive layer I 2 and the bonding force between the conductive layer II 3 and the barrier layer II 5 are both ⁇ 0.5N/15mm, for example, 0.5N/15mm, 1N/15mm, 2N/15mm, 2.5N/15mm, 3N/15mm, 4N/15mm, 6N/15mm, 8N/15mm, 10N/15mm, 20N/15mm, or any value between the aforementioned values.
  • the bonding force between the barrier layer I 4 and the conductive layer I 2 and the bonding force between the conductive layer II 3 and the barrier layer II 5 are tested by a universal tensile testing machine.
  • a universal tensile testing machine see the National Standard of the People's Republic of China GB/T2792-2014 (Test method for peel strength of adhesive tape).
  • the materials of the conductive layer I 2 and the conductive layer II 3 are independently selected from a single metal II or an alloy II; wherein the single metal II is selected from one of aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum and tungsten; preferably, the single metal II is selected from one of aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum and tungsten with a purity of ⁇ 98wt%, preferably 99-100wt%; wherein the metal in the alloy II is selected from at least one of aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum, tungsten, manganese, magnesium and zinc, and the alloy II also includes an optional non-metal, and the non-metal is selected from at least one of carbon, nitrogen and silicon.
  • the alloy II is selected from at least one of aluminum-copper alloy, aluminum-
  • the thickness of the conductive layer I 2 and the conductive layer II 3 are independently selected from 0.1-2 ⁇ m, for example, 0.1 ⁇ m, 0.2 ⁇ m, 0.3 ⁇ m, 0.5 ⁇ m, 0.8 ⁇ m, 1 ⁇ m, 1.2 ⁇ m, 1.5 ⁇ m, 1.8 ⁇ m, 2 ⁇ m, or any value between the aforementioned values, preferably 0.2-1.5 ⁇ m.
  • the conductive layer is a continuous film and has a conductive function.
  • the conductive layer cannot be too thin, otherwise the resistivity will be very high due to the large size effect of the metal film, affecting the internal resistance of the battery cell; the conductive layer cannot be too thick, otherwise it will increase the process cost, material utilization efficiency, etc. Therefore, the thickness of the conductive layer is preferably 0.2-1.5 ⁇ m.
  • the bonding force between the conductive layer I 2 and the polymer layer 1 and the bonding force between the polymer layer 1 and the conductive layer II 3 are both ⁇ 0.5N/15mm, for example, 0.5N/15mm, 1N/15mm, 2N/15mm, 2.5N/15mm, 3N/15mm, 4N/15mm, 6N/15mm, 8N/15mm, 10N/15mm, 20N/15mm, or any value between the aforementioned values.
  • the bonding force between the conductive layer I 2 and the polymer layer 1 and the bonding force between the polymer layer and the conductive layer II are tested using a universal tensile testing machine.
  • a universal tensile testing machine see the National Standard of the People's Republic of China GB/T 2792-2014 (Test method for peel strength of adhesive tape).
  • the resistivity of the conductive layer I 2 and the conductive layer II 3 is ⁇ 8 ⁇ cm, for example, 1 ⁇ cm, 2 ⁇ cm, 3 ⁇ cm, 4 ⁇ cm, 5 ⁇ cm, 6 ⁇ cm, 7 ⁇ cm, 8 ⁇ cm, or any value between the aforementioned values, preferably 2-5 ⁇ cm.
  • the resistivity test method refers to ASTM F390 (Standard Test Method for Determining the Sheet Resistance of Metal Films by Colinear Four-Probe Method) of the United States.
  • the material of the polymer layer 1 is selected from at least one of acrylonitrile-butadiene-styrene copolymer (ABS), polyterephthalate (PET), polybutylene terephthalate (PBT), poly(p-phenylene terephthalamide) (PPA), polyimide (PI), polyamide (PA), polyethylene (PE), polystyrene (PS), polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polytetrafluoroethylene, polypropylene (PPE), polypropylene (PP), polycarbonate (PC), polyoxymethylene (POM), epoxy resin and phenolic resin.
  • ABS acrylonitrile-butadiene-styrene copolymer
  • PET polyterephthalate
  • PBT polybutylene terephthalate
  • PPA poly(p-phenylene terephthalamide)
  • PI polyimide
  • PA polyamide
  • PA polyethylene
  • PS
  • the thickness of the polymer layer 1 is 1-15 ⁇ m, preferably 1-10 ⁇ m.
  • reducing the thickness of the polymer layer can improve the energy density of the battery, but if the thickness of the polymer layer is too small, it is easy to break during the processing of the electrode sheet.
  • the inventor of the present application has found through research that when the thickness of the polymer layer is within the above-defined range, the processing performance and electrical performance of the negative electrode current collector are better.
  • the tensile strength of the polymer layer 1 material is ⁇ 150MPa, such as 150MPa, 180MPa, 200MPa, 250MPa, 300MPa, 400MPa, 500MPa, 600MPa, or any value between the aforementioned values, preferably 150-400MPa.
  • the polymer layer is the substrate of the negative electrode current collector, which mainly plays a supporting role, can ensure the mechanical strength of the composite current collector and extend the service life.
  • the tensile strength test is shown in China's HG/T 2580-2008 (Determination of tensile strength and elongation at break of rubber or plastic coated fabrics).
  • the thermal shrinkage rate of the polymer layer 1 material after treatment at 150°C for 30 minutes is ⁇ 3%, preferably 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, or any value between the aforementioned values.
  • the test of thermal shrinkage rate after treatment at 150°C for 30 minutes is specified in ASTM D-1204 (Test method for linear dimensional change of non-rigid thermoplastic plastic sheets or films at high temperatures) specified by the American Society for Testing and Materials.
  • the material of the blocking layer I 4 and the blocking layer II 5 are the same, and the material of the conductive layer I 2 and the conductive layer II 3 are the same.
  • the negative electrode current collector further includes an intermediate layer I 6 and an intermediate layer II 7, wherein the intermediate layer I 6 is arranged between the blocking layer I 4 and the conductive layer I 2, and the intermediate layer II 7 is arranged between the blocking layer II 5 and the conductive layer II 3.
  • the structure of the negative electrode current collector may be barrier layer I-intermediate layer I-conductive layer I-polymer layer-conductive layer II-intermediate layer II-barrier layer II, that is, barrier layer I, intermediate layer I, conductive layer I, polymer layer, conductive layer II, intermediate layer II and barrier layer II in sequence.
  • intermediate layer I and intermediate layer II can slow down the galvanic corrosion tendency and alloying degree of copper and aluminum, and provide stability of lithium-ion batteries.
  • the materials of the intermediate layer I 6 and the intermediate layer II 7 are independently selected from a single metal III, an alloy III, an oxide semiconductor or a conductive compound.
  • the single metal III is selected from one of Cu, Cr, Ta, Zn, Cd, In, Tl, Mn, Co, Mo, Fe, Sn, Ge, Bi, Sb, Re, Ti, V, Ni, Nb and Tc, preferably selected from one of Ti, V, Cr, Mn, Fe, Co, Ni and Cu;
  • the metal in the alloy III is selected from at least one of Cu, Cr, Ta, Zn, Cd, In, Tl, Mn, Co, Mo, Fe, Sn, Ge, Bi, Sb, Re, Ti, V, Ni, Nb and Tc, preferably selected from at least one of Ti, V, Cr, Mn, Fe, Co, Ni and Cu;
  • the oxide semiconductor is at least one selected from Cu 2 O, ZnO, SnO 2 , Fe 2 O 3 , TiO 2 , ZrO 2 , Co 2 O 3 , WO 3 , In 2 O 3 , Al 2 O 3 and Fe 3 O 4;
  • the conductive compound is selected from at least one of TiB2 , TiC, TiN, ZrB2 , ZrC, ZrN, VB2 , VC, VN, NbB2 , NbC, NbN, TaB2 , TaC , CrB2 , Cr3C2 , CrN , Mo2C , Mo2B5 , W2B5 , WC and LaB6 .
  • the intermediate layer I and the intermediate layer II are respectively and independently at least one of nickel, nickel-based alloy, copper-based alloy and titanium nitride, preferably titanium nitride.
  • the thickness of the intermediate layer I 6 and the intermediate layer II 7 is 1-1000nm, for example, 1nm, 10nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, or any value between the aforementioned values, preferably 5-500nm.
  • the corrosion resistance of the negative electrode collector can be further improved and the alloying degree of the conductive layer can be reduced.
  • the negative electrode current collector also includes a bonding layer I 8 and a bonding layer II 9; wherein the bonding layer I 8 is arranged between the conductive layer I 2 and the polymer layer 1, for connecting the conductive layer I 2 and the polymer layer 1; the bonding layer II 9 is arranged between the conductive layer II 3 and the polymer layer 1, for connecting the conductive layer II 3 and the polymer layer 1.
  • the structure of the negative electrode current collector can be blocking layer I-intermediate layer I-conductive layer I-bonding layer I-polymer layer-bonding layer II-conductive layer II-intermediate layer II-blocking layer II, that is, it includes blocking layer I, intermediate layer I, conductive layer I, bonding layer I, polymer layer, bonding layer II, conductive layer II, intermediate layer II and blocking layer II in sequence.
  • the materials of the bonding layer I 8 and the bonding layer II 9 are independently selected from at least one of ethyl cellulose, methylene succinic acid, styrene, carboxymethyl cellulose, guanidinoacetic acid, isocyanate, polyurethane, chitosan, polycaprolactone and styrene-butadiene latex, and optionally nano-silicon dioxide, nano-aluminum oxide and graphene oxide. At least one of.
  • the thickness of the bonding layer I 8 and the bonding layer II 9 are each independently selected from 0.2-3 ⁇ m, for example, 0.2 ⁇ m, 0.8 ⁇ m, 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, or any value between the aforementioned values, preferably 0.5-1 ⁇ m.
  • the material of the intermediate layer I 6 and the intermediate layer II 7 are the same, and the material of the bonding layer I 8 and the bonding layer II 9 are the same.
  • the lithium-ion battery prepared using the negative electrode current collector provided in the present application has a good cycle life, small battery polarization, little tendency to be corroded by the battery electrolyte, and a high weight energy density, which changes the traditional view that aluminum can only be used as a positive electrode current collector, and has a major change and innovation in the current collector structure of lithium-ion batteries, which is of great significance.
  • the corrosion rate of the negative electrode current collector is ⁇ 0.5mm/a.
  • the test method for the corrosion resistance of the negative electrode current collector is: at room temperature, using a three-electrode system, the working electrode is the negative electrode current collector electrode, the counter electrode is a platinum electrode, the reference electrode is a non-mercury ion electrode, the electrolyte is a 1 mol/L lithium hexafluorophosphate organic solution (wherein the mass ratio of diethyl carbonate (DEC), dimethyl carbonate (DMC) and ethylene carbonate (EC) is 1:1:1), using an electrochemical workstation, measuring the Tafel curve of the negative electrode current collector, the comparison sample is a traditional copper-aluminum foil current collector, and the corrosion rates of the negative electrode current collector and the traditional copper-aluminum foil current collector are listed.
  • DEC diethyl carbonate
  • DMC dimethyl carbonate
  • EC ethylene carbonate
  • the second aspect of the present application provides a method for preparing a negative electrode current collector, wherein the method comprises: first preparing a conductive layer I and a conductive layer II on the upper surface and the lower surface of a polymer layer, respectively, and then preparing a blocking layer I on the conductive layer I, and preparing a blocking layer II on the conductive layer II.
  • the method comprises: first preparing a conductive layer I and a conductive layer II on the upper surface and the lower surface of the polymer layer respectively by evaporation, and then preparing a blocking layer I on the conductive layer I and a blocking layer II on the conductive layer II by evaporation or sputtering.
  • the adhesive layer I and the adhesive layer II are respectively prepared by coating on the upper and lower surfaces of the polymer layer.
  • the intermediate layer I is prepared on the conductive layer I by magnetron sputtering, reactive sputtering or active reactive evaporation, and the intermediate layer II is prepared on the conductive layer II.
  • the evaporation is vacuum evaporation
  • the operating conditions of the vacuum evaporation include: vacuum degree higher than 10-3Pa; cold roller temperature of -25°C to 35°C; ES distance ⁇ 50mm; evaporation temperature ⁇ 800°C.
  • the operating conditions of the magnetron sputtering include: vacuum degree higher than 10-3Pa; main roller temperature of -25°C to 35°C; main roller speed of less than 20m/min; sputtering power of less than 20kW.
  • the operating conditions of the active reaction evaporation include: vacuum degree higher than 10-3Pa; cold roller temperature of -25°C to 35°C; ES distance ⁇ 50mm; evaporation temperature ⁇ 400°C.
  • vacuum degree is as follows: the rarefaction of gas in vacuum state. The smaller the value, the thinner the gas and the higher the vacuum degree.
  • ES distance refers to the distance between the evaporation source and the substrate.
  • the evaporation source refers to the conductive metal material that is heated and evaporated in the vacuum evaporation chamber and vaporized.
  • the substrate refers to the pre-evaporated film material, such as a polymer film.
  • the preparation method of titanium nitride is active reaction evaporation (ARE), that is, in the vacuum deposition coating process, a certain amount of active reaction gas (such as N2 ) that reacts with metal vapor is introduced into the vacuum chamber, and various different discharge methods are used to activate and ionize the molecules and atoms of the metal vapor and the reaction gas, promote the chemical reaction between them, and obtain a compound coating on the surface of the workpiece.
  • ARE active reaction evaporation
  • the third aspect of the present application provides a lithium-ion battery comprising the negative electrode current collector described in the first aspect of the present application.
  • Thickness GB/T 11378-2005 (Metallic coating thickness measurement profilometer method).
  • Sheet resistance/resistivity American ASTM F390 (Standard test method for determining the sheet resistance of metal films by the collinear four-probe method).
  • Bonding strength GB/T 2792-2014 (Test method for peel strength of adhesive tape).
  • HG/T 2580-2008 Determination of tensile strength and elongation at break of rubber or plastic coated fabrics.
  • Wetting tension GB/T 22638.4-2016 (Aluminum foil test method Part 4: Determination of surface wetting tension).
  • Test method for corrosion resistance of negative electrode composite current collector at room temperature, using a three-electrode system, with the working electrode being the negative electrode
  • the current collector is a platinum electrode
  • the reference electrode is a non-mercury ion electrode
  • the electrolyte is a 1 mol/L lithium hexafluorophosphate organic solution (wherein the mass ratio of diethyl carbonate (DEC), dimethyl carbonate (DMC) and ethylene carbonate (EC) is 1:1:1)
  • an electrochemical workstation is used to measure the metal foil, the Tafel curve of the coupled metal platinum sheet, and the corrosion resistance is calculated using the Tafel curve.
  • corrosion resistance is characterized by corrosion rate.
  • the corrosion rate of the negative electrode composite current collector is ⁇ 0.1 mm/a.
  • Preparation method of battery cell negative electrode active material is coated on the surface of composite current collector, after drying, negative electrode coil is obtained, after roller pressing and die cutting, compacted positive and negative electrode sheets are obtained, which are stacked by Z-shaped stacking machine, and the tabs are welded and packaged to obtain uninjected battery cells, which are aged after liquid injection and hot pressed to activate into battery cells, aged, and finally sealed to obtain battery cells.
  • metal Al was vacuum deposited on the upper and lower surfaces of 6 ⁇ m PET respectively, and then 300nm metal Cu was deposited on the surface of metal Al respectively.
  • the composite current collector after film formation was used as the negative electrode current collector, and a battery cell was prepared through the above process.
  • the performance of the battery cell was tested, and the electrochemical performance of the composite current collector material was characterized.
  • the test results are shown in Tables 1 and 2.
  • 1 ⁇ m metal Al was vacuum deposited on the upper and lower surfaces of 6 ⁇ m PET respectively, and then 800nm metal Cu was deposited on the surface of Al respectively.
  • the composite current collector after film formation was used as the negative electrode current collector, and a battery cell was prepared through the above process.
  • the performance of the battery cell was tested, and the electrochemical performance of the composite current collector material was characterized.
  • the test results are shown in Tables 1 and 2.
  • FIG4 is a cross-sectional TEM image of the negative electrode current collector obtained in Example 2. It can be seen from FIG4 that the thickness of the barrier layer is dense and continuous enough to prevent LiAl from reacting, so that this structural material can be applied to the negative electrode.
  • metal Al was vacuum deposited on the upper and lower surfaces of 6 ⁇ m PET respectively.
  • 30nm metal Ni was magnetron sputtering deposited on the upper and lower surfaces of Al respectively.
  • 300nm metal Cu was vacuum deposited on the upper and lower surfaces of Ni respectively.
  • the composite current collector after film formation was used as the negative electrode current collector, and a battery cell was prepared through the above process.
  • the performance of the battery cell was tested, and the electrochemical performance of the composite current collector material was characterized.
  • the test results are shown in Tables 1 and 2.
  • metal Al was vacuum deposited on the upper and lower surfaces of 6 ⁇ m PET respectively.
  • 30nm metal Ni was magnetron sputtering deposited on the surface of Al respectively.
  • 800nm metal Cu was vacuum deposited on the upper and lower surfaces of metal Ni respectively.
  • the composite current collector after film formation was used as the negative electrode current collector, and a battery cell was prepared through the above process.
  • the performance of the battery cell was tested, and the electrochemical performance of the composite current collector material was characterized.
  • the test results are shown in Tables 1 and 2.
  • metal Al was vacuum deposited on the upper and lower surfaces of 6 ⁇ m PET respectively.
  • 30nm metal chemical TiN was deposited on the surface of Al by active reaction evaporation (ARE).
  • 300nm metal Cu was vacuum deposited on the upper and lower surfaces of metal compound TiN respectively.
  • the composite current collector after film formation was used as the negative electrode current collector, and a battery cell was prepared through the above process.
  • the performance of the battery cell was tested, and the electrochemical performance of the composite current collector material was characterized.
  • the test results are shown in Tables 1 and 2.
  • metal Al was vacuum deposited on the upper and lower surfaces of 6 ⁇ m PET respectively.
  • 30nm metal chemical TiN was deposited on the surface of Al by active reaction evaporation (ARE).
  • 800nm metal Cu was vacuum deposited on the upper and lower surfaces of metal compound TiN respectively.
  • the composite current collector after film formation was used as the negative electrode current collector, and a battery cell was prepared through the above process.
  • the performance of the battery cell was tested, and the electrochemical performance of the composite current collector material was characterized.
  • the test results are shown in Tables 1 and 2.
  • nano-silica modified itaconic acid was coated on the upper and lower surfaces of 6 ⁇ m PET by a coater. After drying, 1 ⁇ m metal Al was vacuum deposited on the surface of the bonding layer at one time, and then 300nm metal Cu was deposited on the surface of Al.
  • the composite current collector after film formation was used as the negative electrode current collector, and a battery cell was prepared through the above process.
  • the performance of the battery cell was tested, and the electrochemical performance of the composite current collector material was characterized.
  • the test results are shown in Tables 1 and 2.
  • nano-silica modified itaconic acid was coated on the upper and lower surfaces of 6 ⁇ m PET respectively. After drying, 1 ⁇ m metal Al was vacuum deposited on the surface of the bonding layer at one time, and then 800nm metal Cu was deposited on the surface of Al.
  • the composite current collector after film formation was used as the negative electrode current collector, and a battery cell was prepared through the above process.
  • the performance of the battery cell was tested, and the electrochemical performance of the composite current collector material was characterized.
  • the test results are shown in Tables 1 and 2.
  • 1 ⁇ m nano-silica modified itaconic acid was coated on the upper and lower surfaces of 6 ⁇ m PET respectively.
  • 1 ⁇ m metal Al was vacuum deposited on the surface of the bonding layer at one time, and then 30nm metal Ni was magnetron sputtering deposited on the surface of Al, and then 300nm metal Cu was deposited on the surface of metal Ni at one time.
  • the composite current collector after film formation was used as the negative electrode current collector, and a battery cell was prepared through the above process.
  • the performance of the battery cell was tested, and the electrochemical performance of the composite current collector material was characterized.
  • the test results are shown in Tables 1 and 2.
  • 1 ⁇ m nano-silica modified itaconic acid was coated on the upper and lower surfaces of 6 ⁇ m PET respectively.
  • 1 ⁇ m metal Al was vacuum deposited on the surface of the bonding layer at one time, and then 30nm metal Ni was magnetron sputtered on the surface of Al, and then 800nm metal Cu was deposited on the surface of metal Ni at one time.
  • the composite current collector after film formation was used as the negative electrode current collector, and a battery cell was prepared through the above process.
  • the performance of the battery cell was tested, and the electrochemical performance of the composite current collector material was characterized.
  • the test results are shown in Tables 1 and 2.
  • nano-silica modified itaconic acid was coated on the upper and lower surfaces of 6 ⁇ m PET respectively by a coater. After drying, 1 ⁇ m metal Al was vacuum deposited on the surface of the bonding layer at one time. Then, 30nm metal chemical TiN was deposited on the surface of Al by active reaction evaporation (ARE). Finally, 300nm metal Cu was deposited on the surface of the metal compound TiN at one time.
  • ARE active reaction evaporation
  • the composite current collector after film formation was used as the negative electrode current collector, and a battery cell was prepared through the above process.
  • the performance of the battery cell was tested, and the electrochemical performance of the composite current collector material was characterized.
  • the test results are shown in Tables 1 and 2.
  • nano-silica modified itaconic acid was coated on the upper and lower surfaces of 6 ⁇ m PET respectively by a coater. After drying, 1 ⁇ m metal Al was vacuum deposited on the surface of the bonding layer at one time. Then, 30nm metal chemical TiN was deposited on the surface of Al by active reaction evaporation (ARE). Finally, 800nm metal Cu was deposited on the surface of the metal compound TiN at one time.
  • ARE active reaction evaporation
  • the composite current collector after film formation was used as the negative electrode current collector, and a battery cell was prepared through the above process.
  • the performance of the battery cell was tested, and the electrochemical performance of the composite current collector material was characterized.
  • the test results are shown in Tables 1 and 2.
  • 1 ⁇ m metal Al was directly evaporated on the upper and lower surfaces of 6 ⁇ m PET respectively.
  • the composite current collector after film formation was used as the negative electrode current collector, and a battery cell was prepared through the above process.
  • the performance of the battery cell was tested, and the electrochemical performance of the composite current collector material was characterized.
  • the test results are shown in Tables 1 and 2.

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Abstract

本申请涉及集流体技术领域，具体涉及一种负极集流体及其制备方法和锂离子电池。所述负极集流体依次包括阻挡层I、导电层I、聚合物层、导电层II和阻挡层II。本申请中提供的负极集流体，阻挡层I和阻挡层II为连续、致密的薄膜结构，可以防止导电层I和导电层II中的导电材料合金化，能提高集流体的导电性，可替代传统的铜作为负极集流体，具有生产成本低、耐腐蚀性能好、电化学稳定、厚度薄、质量轻、导电率小和安全性高的优点，适合工业化推广。

Description

负极集流体及其制备方法和锂离子电池
相关申请的交叉引用
本申请要求在2022年12月23日提交中国专利局、申请号为“2022116650818”，申请名称为“负极集流体及其制备方法和锂离子电池”中国专利申请的优先权，全部内容通过引用结合在本申请中。
技术领域
本申请涉及集流体技术领域，具体涉及一种负极集流体及其制备方法和锂离子电池。
背景技术
锂离子电池一般选用铝作正极集流体金属材料，铜作负极集流体金属材料。这是因为，金属铝的氧化电位高，且金属铝的晶格八面体空隙大小与锂大小相近，使得金属铝极易与锂发生反应形成LiAl、Li3Al2、Li4Al3等合金，不仅消耗大量的Li+，还会破坏金属铝本身的结构和形态，因而铝能作为锂离子电池正极的集流体，但是不能作为锂离子电池负极的集流体。Cu在电池充放电过程中，只有很少的嵌锂容量，并且保持了结构和电化学性能的稳定，因而可作为离子电池负极的集流体。
随着锂离子电池技术的不断发展，市场需求对锂离子电池的能量密度和重量提出了越来越高的要求。这使得未来的锂离子电池的集流体向着薄而轻、高导电、高化学与电化学稳定性的方向发展。简单的铜箔和铝箔已经无法满足市场需求，因而人们研发了复合集流体。但是，目前的复合集流体普遍存在质量大、机械强度低、导电层易脱落、易被电解液腐蚀、导电率低的问题。
因此，亟待提供一种具有耐腐蚀、电化学稳定、厚度薄、质量轻、导电率高等优点的负极集流体及其制备方法。
发明内容
本申请的目的是为了克服现有技术存在的负极集流体质量重、机械强度低、导电层易脱落、易被电解液腐蚀、电阻率大的问题，提供一种负极集流体及其制备方法和锂离子电池。
为了实现上述目的，本申请的第一方面提供了一种负极集流体，所述负极集流体按照顺序依次包括阻挡层I、导电层I、聚合物层、导电层II和阻挡层II。
本申请的第二方面提供了一种负极集流体的制备方法，所述方法包括：先在聚合物层的上表面和下表面上分别制备导电层I和导电层II，之后再在所述导电层I上制备阻挡层I，在所述导电层II上制备阻挡层II。
本申请的第三方面提供了一种包括本申请第一方面所述的负极集流体的锂离子电池。
通过上述技术方案，本申请所取得的有益技术效果如下：
1)本申请中提供的负极集流体，可替代传统的铜箔作为负极集流体，节约铜资源和成本，提高安全性；
2)本申请中提供的负极集流体，通过设置中间层I和中间层II，可减缓铜铝的电偶腐蚀倾向和合金化程度；
3)本申请中提供的负极集流体，设置阻挡层I和阻挡层II，可阻隔Li-Al合金的生成，提高负极集流体的导电率。
附图说明
图1是本申请所述的负极集流体的第一种结构示意图；
图2是本申请所述的负极集流体的第二种结构示意图；
图3是本申请所述的负极集流体的第三种结构示意图；
图4为实施例2得到的负极集流体的截面TEM图。
附图标记说明
1聚合物层；2导电层I；3导电层II；4阻挡层I；5阻挡层II；6中间层I；7中间层II；8粘结层I；9粘结层II。
具体实施方式
在本文中所披露的范围的端点和任何值都不限于该精确的范围或值，这些范围或值应当理解为包含接近这些范围或值的值。对于数值范围来说，各个范围的端点值之间、各个范围的端点值和单独的点值之间，以及单独的点值之间可以彼此组合而得到一个或多个新的数值范围，这些数值范围应被视为在本文中具体公开。
本申请的第一方面提供了一种负极集流体，如图1所示，所述负极集流体按照顺序依次包括阻挡层I 4、导电层I 2、聚合物层1、导电层II 3和阻挡层II 5。
其中，在本申请中，阻挡层I 4和阻挡层II 5为连续、致密的薄膜结构，可以防止导电层I 2和导电层II 3中的导电材料合金化，能提高集流体的导电性。
在一个实施方式中，所述阻挡层I和阻挡层II的材料与所述导电层I和导电层II的材料不同。
在一个优选的实施方式中，所述阻挡层I 4和阻挡层II 5的材料分别独立地选自单一金属I或合金I；其中，所述单一金属I选自铝、铜、镍、铁、钛、银、金、钴、铬、钼和钨中的一种；优选地，所述单一金属I选自纯度≥98wt％，优选纯度为99-100wt％的铝、铜、镍、铁、钛、银、金、钴、铬、钼和钨的一种；其中，所述合金I中的金属选自铝、铜、镍、铁、钛、银、金、钴、铬、钼、钨中的至少一种，所述合金I还包括任选的非金属，所述非金属选自碳、氮和硅中的至少一种。优选地，所述合金I选自铜铝合金、铜镍合金、铜锌合金和铜锡合金中的至少一种。
在一个优选的实施方式中，所述阻挡层I 4和阻挡层II 5的厚度分别独自地选自1-1500nm，例如1nm、10nm、100nm、500nm、800nm、1000nm、1200nm、1400nm、1500nm，或前述数值之间的任意值，优选为10-1000nm。
在本申请中，阻挡层的作用是阻挡Al在负极端的暴露，同时具有导电作用。本申请的阻挡层是连续致密薄膜；阻挡层不能太薄，否则短时间内(几天或几周)就会和导电层发生互扩散，而使得Al暴露，失去阻挡层原本的作用；阻挡层也不能太厚，否则会增加工艺成本，材料使用效率等等，因此，阻挡层的厚度优选为10-1000nm，更优选为30nm-800nm。
在一个优选的实施方式中，所述阻挡层I 4与导电层I 2之间的结合力和所述导电层II 3和阻挡层II 5之间的结合力均≥0.5N/15mm，例如0.5N/15mm、1N/15mm、2N/15mm、2.5N/15mm、3N/15mm、4N/15mm、6N/15mm、8N/15mm、10N/15mm、20N/15mm，或前述数值之间的任意值。
其中，在本申请中，阻挡层I 4与导电层I 2之间的结合力和导电层II 3和阻挡层II 5之间的结合力采用万能拉力机进行测试，具体测试方法见中华人民共和国国家标准GB/T2792-2014(胶粘带剥离强度的试验方法)。
在一个优选的实施方式中，所述导电层I 2和导电层II 3的材料分别独自地选自单一金属II或合金II；其中，所述单一金属II选自铝、铜、镍、铁、钛、银、金、钴、铬、钼和钨中的一种；优选地，所述单一金属II选自纯度≥98wt％，优选纯度为99-100wt％的铝、铜、镍、铁、钛、银、金、钴、铬、钼和钨中的一种；其中，所述合金II中的金属选自铝、铜、镍、铁、钛、银、金、钴、铬、钼、钨、锰、镁和锌中的至少一种，所述合金II还包括任选的非金属，所述非金属选自碳、氮、硅中的至少一种。优选地，所述合金II选自铝铜合金、铝锰合金、铝硅合金、铝镁合金、铝镁硅合金和铝锌合金中的至少一种。
在一个优选的实施方式中，所述导电层I 2和导电层II 3的厚度分别独立地选自0.1-2μm，例如0.1μm、0.2μm、0.3μm、0.5μm、0.8μm、1μm、1.2μm、1.5μm、1.8μm、2μm，或前述数值之间的任意值，优选为0.2-1.5μm。
在本申请中，导电层为连续薄膜且具有导电作用。导电层不能太薄，否则由于金属薄膜的尺寸效应过于大，电阻率会很高，影响电芯的内阻；导电层也不能太厚，否则会增加工艺成本，材料使用效率等等，因此，导电层的厚度优选为0.2-1.5μm。在一个优选的实施方式中， 所述导电层I 2与聚合物层1之间的结合力和所述聚合物层1与导电层II 3之间的结合力均≥0.5N/15mm，例如0.5N/15mm、1N/15mm、2N/15mm、2.5N/15mm、3N/15mm、4N/15mm、6N/15mm、8N/15mm、10N/15mm、20N/15mm，或前述数值之间的任意值。
其中，在本申请中，导电层I 2与聚合物层1之间的结合力和聚合物层与导电层II之间的结合力采用万能拉力机进行测试，具体测试方法见中华人民共和国国家标准GB/T 2792-2014(胶粘带剥离强度的试验方法)。
在一个优选的实施方式中，所述导电层I 2和导电层II 3的电阻率≤8μΩ·cm，例如1μΩ·cm、2μΩ·cm、3μΩ·cm、4μΩ·cm、5μΩ·cm、6μΩ·cm、7μΩ·cm、8μΩ·cm，或前述数值之间的任意值，优选为2-5μΩ·cm。在本申请中，电阻率的测试方法参考美国的ASTMF390(用共线四探针法测定金属薄膜的薄膜电阻的标准试验方法)。
在一个优选的实施方式中，所述聚合物层1的材料选自丙烯腈-丁二烯-苯乙烯共聚物(ABS)、聚对苯二甲酸酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚对苯二甲酰对苯二胺(PPA)、聚酰亚胺(PI)、聚酰胺(PA)、聚乙烯(PE)、聚苯乙烯(PS)、聚偏氟乙烯(PVDF)、聚氯乙烯(PVC)、聚四氟乙烯、聚丙乙烯(PPE)、聚丙烯(PP)、聚碳酸酯(PC)、聚甲醛(POM)、环氧树脂和酚醛树脂中的至少一种。
在一个优选的实施方式中，所述聚合物层1的厚度为1-15μm，优选为1-10μm。
在本申请中，降低聚合物层的厚度，可提高电池的能量密度，但聚合物层的厚度太小，在极片加工的过程中容易发生断裂。本申请的发明人经过研究发现，聚合物层的厚度在上述限定的范围内时，负极集流体的加工性能和电学性能更佳。
在一个优选的实施方式中，所述聚合物层1材料的抗拉强度≥150MPa，例如150MPa、180MPa、200MPa、250MPa、300MPa、400MPa、500MPa、600MPa，或前述数值之间的任意值，优选为150-400MPa。其中，在本申请中，聚合物层为负极集流体的基底，主要起支撑作用，可保证复合集流体的机械强度，延长使用寿命。在本申请中，抗拉强度的测试见中国的HG/T 2580-2008(橡胶或塑料涂覆织物拉伸强度和拉断伸长率的测定)。
在一个优选的实施方式中，所述聚合物层1材料在150℃下处理30min后的热收缩率≤3％，优选为0.5％、1％、1.5％、2％、2.5％、3％，或前述数值之间的任意值。其中，150℃下处理30min后的热收缩率的测试见美国材料与试验协会规定的ASTM D-1204(高温下非硬性热塑塑料薄板或薄膜线性尺寸变化的测试方法)。
在一个优选的实施方式中，所述阻挡层I 4和阻挡层II 5的材料相同，所述导电层I 2和导电层II 3的材料相同。
在一个优选的实施方式中，如图2所示，所述负极集流体还包括中间层I 6和中间层II 7，其中，所述中间层I 6设置在阻挡层I 4和导电层I 2之间，所述中间层II 7设置在阻挡层II 5和导电层II 3之间。
也即，在本申请中，所述负极集流体的结构可以是阻挡层I-中间层I-导电层I-聚合物层-导电层II-中间层II-阻挡层II，即依次包括阻挡层I、中间层I、导电层I、聚合物层、导电层II、中间层II和阻挡层II。其中，在本申请中，中间层I和中间层II可以减缓铜铝的电偶腐蚀倾向和合金化程度，提供锂离子电池的稳定性。
在一个优选的实施方式中，所述中间层I 6和中间层II 7的材料分别独立地选自单一金属III、合金III、氧化物半导体或导电化合物。
其中，所述单一金属III选自Cu、Cr、Ta、Zn、Cd、In、Tl、Mn、Co、Mo、Fe、Sn、Ge、Bi、Sb、Re、Ti、V、Ni、Nb和Tc中的一种，优选选自Ti、V、Cr、Mn、Fe、Co、Ni和Cu中的一种；
其中，所述合金III中的金属选自Cu、Cr、Ta、Zn、Cd、In、Tl、Mn、Co、Mo、Fe、Sn、Ge、Bi、Sb、Re、Ti、V、Ni、Nb和Tc中的至少一种，优选选自Ti、V、Cr、Mn、Fe、Co、Ni和Cu中的至少一种；
其中，所述氧化物半导体选自Cu2O、ZnO、SnO2、Fe2O3、TiO2、ZrO2、Co2O3、WO3、In2O3、Al2O3和Fe3O4中的至少一种；
其中，所述导电化合物选自TiB2、TiC、TiN、ZrB2、ZrC、ZrN、VB2、VC、VN、NbB2、NbC、NbN、TaB2、TaC、CrB2、Cr3C2、CrN、Mo2C、Mo2B5、W2B5、WC和LaB6中的至少一种。
在一个优选的实施方式种，所述中间层I和中间层II分别独自为镍、镍基合金、铜基合金和氮化钛中的至少一种，优选为氮化钛。
在一个优选的实施方式中，所述中间层I 6和中间层II 7的厚度分别独自地为1-1000nm，例如1nm、10nm、100nm、200nm、300nm、400nm、500nm、600nm、700nm、800nm、900nm、1000nm，或前述数值之间的任意值，优选5-500nm。其中，在本申请中，中间层I 6和中间层II 7的厚度在上述限定范围内时，可进一步改善负极集流体的耐腐蚀性，降低导电层的合金化程度。
在一个优选的实施方式中，如图3所示，所述负极集流体还包括粘结层I 8和粘结层II 9；其中，所述粘结层I 8设置在导电层I 2和聚合物层1之间，用于连接导电层I 2和聚合物层1；所述粘结层II 9设置在导电层II 3和聚合物层1之间，用于连接导电层II 3和聚合物层1。
也即，在本申请中，所述负极集流体的结构可以是阻挡层I-中间层I-导电层I-粘结层I-聚合物层-粘结层II-导电层II-中间层II-阻挡层II，即依次包括阻挡层I、中间层I、导电层I、粘结层I、聚合物层、粘结层II、导电层II、中间层II和阻挡层II。
在一个优选的实施方式中，所述粘结层I 8和粘结层II 9的材料分别独立地选自乙基纤维素、亚甲基丁二酸、苯乙烯、羧甲基纤维素、胍基乙酸、异氰酸酯、聚氨酯、壳聚糖、聚己内酯和丁苯胶乳中的至少一种，以及任选的纳米二氧化硅、纳米三氧化二铝和氧化石墨烯中 的至少一种。
在一个优选的实施方式中，所述粘结层I 8和粘结层II 9的厚度分别独自地选自0.2-3μm，例如0.2μm、0.8μm、1μm、2μm、3μm，或前述数值之间的任意值，优选0.5-1μm。
在一个优选的实施方式中，所述中间层I 6和中间层II 7的材料相同，所述粘结层I 8和粘结层II 9的材料相同。
其中，利用本申请中提供的负极集流体制备得到的锂离子电池的循环寿命较好，电池的极化较小，受电池电解液的腐蚀倾向小，且重量能量密度较高，改变了传统意义上铝只能做正极集流体的观点，对锂离子电池的集流体结构有着重大的变革和创新，意义重大。
在一个优选的实施方式中，所述负极集流体的腐蚀速率≤0.5mm/a。其中，在本申请中，负极集流体的耐腐蚀性能的测试方法为：室温条件下，利用三电极体系，工作电极为负极集流体电极，对电极为铂电极，参比电极为非水银离子电极，电解液为1mol/L的六氟磷酸锂有机溶液(其中，碳酸二乙酯(DEC)、碳酸二甲酯(DMC)和碳酸乙烯酯(EC)的质量比为1∶1∶1)，使用电化学工作站，测量负极集流体的塔菲尔(tafel)曲线，对比试样为传统铜铝箔集流体，列表给出负极集流体、传统铜铝箔集流体的腐蚀速率。
本申请的第二方面提供了一种负极集流体的制备方法，其中，所述方法包括：先在聚合物层的上表面和下表面上分别制备导电层I和导电层II，之后再在所述导电层I上制备阻挡层I，在所述导电层II上制备阻挡层II。
在一个优选的实施方式中，所述方法包括：先通过蒸镀在聚合物层的上表面和下表面上分别制备导电层I和导电层II，之后再通过蒸镀或溅射在所述导电层I上制备阻挡层I、在所述导电层II上制备阻挡层II。
在一个优选的实施方式中，在通过蒸镀在聚合物层1的上表面和下表面上制备导电层I和导电层II之前，通过涂覆在所述聚合物层的上表面和下表面分别制备粘结层I和粘结层II。
在一个优选的实施方式中，在通过蒸镀或溅射在所述导电层I和导电层II上制备阻挡层I和阻挡层II之前，通过磁控溅射、反应溅射或活性反应蒸镀在所述导电层I上制备中间层I，在所述导电层II上制备中间层II。
在一个优选的实施方式中，所述蒸镀为真空蒸镀，所述真空蒸镀的操作条件包括：真空度高于10-3Pa；冷辊温度为-25℃至35℃；ES距离≥50mm；蒸发温度≥800℃。
在一个优选的实施方式中，所述磁控溅射的操作条件包括：真空度高于10-3Pa；主辊温度为-25℃至35℃；主辊走速为20m/min以下；溅射功率为20kW以下。
在一个优选的实施方式中，所述活性反应蒸镀的操作条件包括：真空度高于10-3Pa；冷辊温度为-25℃至35℃；ES距离≥50mm；蒸发温度≥400℃。
关于真空度的说明如下：真空状态下气体的稀薄程度，数值越小，表示气体越稀薄，真空度越高。
在本申请中，ES距离是指蒸发源与基材的距离。
蒸发源是指在真空蒸镀腔室内加热蒸发并使之气化的导电金属材料。基材是指预蒸镀的膜材，比如聚合物薄膜。
在本申请中，当所述中间层I和中间层II选自氮化钛时，氮化钛的制备方式为活性反应蒸镀(ARE)，即在真空沉积镀膜过程中，在真空室中导入一定量的、与金属蒸气起反应的活性反应气体(例如N2)，并用各种不同的放电方式，使金属蒸气和反应气体的分子、原子激活、离化，促进其间的化学反应，在工件表面获得化合物镀层。
所述活性反应蒸镀的操作可如下进行：
抽真空，同时对基材铝箔烘烤除气，使蒸镀前的真空度维持在10-3Pa或更高。接通电子枪电源，对镀料Ti熔化除气，通过针形阀充入反应气体N2，打开挡板，在基材铝箔上获得化合物镀层。
本申请的第三方面提供了一种包括本申请第一方面所述的负极集流体的锂离子电池。
为了进一步理解本申请，下面将结合本申请实施例，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。
如无特殊说明，本申请实施例中所涉及的试剂均为市售产品，均可以通过商业渠道购买获得。
以下实施例和对比例中，
厚度：GB/T 11378-2005(金属覆盖层覆盖层厚度测量轮廓仪法)。
方阻/电阻率：美国的ASTM F390(用共线四探针法测定金属薄膜的薄膜电阻的标准试验方法)。
结合力：GB/T 2792-2014(胶粘带剥离强度的试验方法)。
机械性能：HG/T 2580-2008(橡胶或塑料涂覆织物拉伸强度和拉断伸长率的测定)。
润湿张力：GB/T 22638.4-2016(铝箔试验方法第4部分：表面润湿张力的测定)。
热收缩：GB/T 12027-2004塑料薄膜和薄片加热尺寸变化率实验方法
负极复合集流体的耐蚀性能的测试方法：室温条件，利用三电极体系，工作电极为负极 集流体，对电极为铂电极，参比电极为非水银离子电极，电解液为1mol/L的六氟磷酸锂有机溶液(其中，碳酸二乙酯(DEC)、碳酸二甲酯(DMC)和碳酸乙烯酯(EC)的质量比为1∶1∶1)，使用电化学工作站，测量金属箔片，耦合金属铂片的塔菲尔(tafel)曲线，利用塔菲尔(tafel)曲线计算耐蚀性能。
在本申请中，用腐蚀速率表征耐蚀性。本申请中负极复合集流体的腐蚀速率≤0.1mm/a。
电芯的制备方法：在复合集流体表面涂敷负极活性材料，经过烘干后，得到负极极卷，经辊压模切后，得到压实的正负极片，通过Z字型叠片机叠片，极耳焊接包装后得到未注液电芯，注液后陈化进行热压化成激活成电芯，陈化，最终二封，得到电芯。
实施例1
先分别在6μm PET的上下表面一次性真空沉积1μm金属Al，然后分别在金属Al的的表面沉积300nm金属Cu。
将成膜后的复合集流体作为负极集流体，经过上述过程制备成电芯，对电芯的性能进行测试，并对复合集流体材料的电化学性能进行表征。测试结果如表1和表2所示。
实施例2
先分别在6μm PET的上下表面一次性真空沉积1μm金属Al，然后分别在Al的表面沉积800nm金属Cu。
将成膜后的复合集流体作为负极集流体，经过上述过程制备成电芯，对电芯的性能进行测试，并对复合集流体材料的电化学性能进行表征。测试结果如表1和表2所示。
图4为实施例2得到的负极集流体的截面TEM图，从图4可以看出，阻挡层厚度足够致密连续，可以阻挡LiAl发生反应，使得此结构材料可应用于负极端。
实施例3
先分别在6μm PET上下表面一次性真空沉积1μm金属Al，然后分别在Al得上下表面磁控溅射沉积30nm金属Ni，在金属Ni的上下表面一次性真空沉积300nm金属Cu。
将成膜后的复合集流体作为负极集流体，经过上述过程制备成电芯，对电芯的性能进行测试，并对复合集流体材料的电化学性能进行表征。测试结果如表1和表2所示。
实施例4
先分别在6μm PET上下表面一次性真空沉积1μm金属Al，然后分别在Al的表面磁控溅射沉积30nm金属Ni，在金属Ni的上下表面一次性真空沉积800nm金属Cu。
将成膜后的复合集流体作为负极集流体，经过上述过程制备成电芯，对电芯的性能进行测试，并对复合集流体材料的电化学性能进行表征。测试结果如表1和表2所示。
实施例5
先分别在6μm PET上下表面一次性真空沉积1μm金属Al，然后分别在Al的表面活性反应蒸镀(ARE)沉积30nm金属化学物TiN，在金属化合物TiN的上下表面一次性真空沉积300nm金属Cu。
将成膜后的复合集流体作为负极集流体，经过上述过程制备成电芯，对电芯的性能进行测试，并对复合集流体材料的电化学性能进行表征。测试结果如表1和表2所示。
实施例6
先分别在6μm PET上下表面一次性真空沉积1μm金属Al，然后分别在Al的表面活性反应蒸镀(ARE)沉积30nm金属化学物TiN，在金属化合物TiN的上下表面一次性真空沉积800nm金属Cu。
将成膜后的复合集流体作为负极集流体，经过上述过程制备成电芯，对电芯的性能进行测试，并对复合集流体材料的电化学性能进行表征。测试结果如表1和表2所示。
实施例7
先分别在6μm PET的上下表面涂布机涂敷1μm的纳米二氧化硅改性衣康酸，经烘干，分别在粘结层的表面一次性真空沉积1μm金属Al，然后分别在Al的表面沉积300nm金属Cu。
将成膜后的复合集流体作为负极集流体，经过上述过程制备成电芯，对电芯的性能进行测试，并对复合集流体材料的电化学性能进行表征。测试结果如表1和表2所示。
实施例8
先分别在6μm PET上下表面涂布机涂敷1μm的纳米二氧化硅改性衣康酸，经烘干，分别在粘结层的表面一次性真空沉积1μm金属Al，然后分别在Al的表面沉积800nm金属Cu。
将成膜后的复合集流体作为负极集流体，经过上述过程制备成电芯，对电芯的性能进行测试，并对复合集流体材料的电化学性能进行表征。测试结果如表1和表2所示。
实施例9
先分别在6μm PET上下表面涂布机涂敷1μm的纳米二氧化硅改性衣康酸，经烘干，分别在粘结层的表面一次性真空沉积1μm金属Al，然后分别在Al的表面磁控溅射沉积30nm金属Ni，再分别在金属Ni的表面一次性沉积300nm金属Cu。
将成膜后的复合集流体作为负极集流体，经过上述过程制备成电芯，对电芯的性能进行测试，并对复合集流体材料的电化学性能进行表征。测试结果如表1和表2所示。
实施例10
先分别在6μm PET上下表面涂布机涂敷1μm的纳米二氧化硅改性衣康酸，经烘干，分别在粘结层的表面一次性真空沉积1μm金属Al，然后分别在Al的表面磁控溅射沉积30nm金属Ni，再分别在金属Ni的表面一次性沉积800nm金属Cu。
将成膜后的复合集流体作为负极集流体，经过上述过程制备成电芯，对电芯的性能进行测试，并对复合集流体材料的电化学性能进行表征。测试结果如表1和表2所示。
实施例11
先分别在6μm PET上下表面涂布机涂敷1μm的纳米二氧化硅改性衣康酸，经烘干，分别在粘结层的表面一次性真空沉积1μm金属Al，然后分别在Al的表面活性反应蒸镀(ARE)沉积30nm金属化学物TiN，再分别在金属化合物TiN的表面一次性沉积300nm金属Cu。
将成膜后的复合集流体作为负极集流体，经过上述过程制备成电芯，对电芯的性能进行测试，并对复合集流体材料的电化学性能进行表征。测试结果如表1和表2所示。
实施例12
先分别在6μm PET上下表面涂布机涂敷1μm的纳米二氧化硅改性衣康酸，经烘干，分别在粘结层的表面一次性真空沉积1μm金属Al，然后分别在Al的表面活性反应蒸镀(ARE)沉积30nm金属化学物TiN，再分别在金属化合物TiN的表面一次性沉积800nm金属Cu。
将成膜后的复合集流体作为负极集流体，经过上述过程制备成电芯，对电芯的性能进行测试，并对复合集流体材料的电化学性能进行表征。测试结果如表1和表2所示。
对比例
分别在6μm PET的上下表面直接蒸镀1μm金属Al。
将成膜后的复合集流体作为负极集流体，经过上述过程制备成电芯，对电芯的性能进行测试，并对复合集流体材料的电化学性能进行表征。测试结果如表1和表2所示。
表1复合集流体材料性能

表2复合集流体电芯性能

通过表1和表2的电芯结果可以看出，采用本申请实施例1-12的具有可以作为负极集流体的能力，这对Al不能应用于负极是一个颠覆性的变更。
以上详细描述了本申请的优选实施方式，但是，本申请并不限于此。在本申请的技术构思范围内，可以对本申请的技术方案进行多种简单变型，包括各个技术特征以任何其它的合适方式进行组合，这些简单变型和组合同样应当视为本申请所公开的内容，均属于本申请的保护范围。

Claims (10)

  1. 一种负极集流体，其特征在于，所述负极集流体依次包括阻挡层I、导电层I、聚合物层、导电层II和阻挡层II。
  2. 根据权利要求1所述的负极集流体，其中，所述阻挡层I和阻挡层II的材料与所述导电层I和导电层II的材料不同。
  3. 根据权利要求1或2所述的负极集流体，其中，所述阻挡层I和阻挡层II的材料分别独立地选自单一金属I或合金I；
    其中，所述单一金属I选自铝、铜、镍、铁、钛、银、金、钴、铬、钼和钨中的一种；
    优选地，所述单一金属I选自纯度≥98wt％，优选纯度为99-100wt％的铝、铜、镍、铁、钛、银、金、钴、铬、钼和钨中的一种；
    其中，所述合金I中的金属选自铝、铜、镍、铁、钛、银、金、钴、铬、钼和钨中的至少一种，进一步优选地，所述合金I选自铜铝合金、铜镍合金、铜锌合金和铜锡合金中的至少一种；
    优选地，所述阻挡层I和阻挡层II的厚度分别独自选自1-1500nm，优选为10-1000nm；
    优选地，所述阻挡层I与导电层I之间的结合力和所述导电层II和阻挡层II之间的结合力均≥0.5N/15mm。
  4. 根据权利要求1-3中任意一项所述的负极集流体，其中，所述导电层I和导电层II的材料分别独立地选自单一金属II或合金II；
    其中，所述单一金属II选自铝、铜、镍、铁、钛、银、金、钴、铬、钼和钨中的一种；
    优选地，所述单一金属II选自纯度≥98wt％，优选纯度为99-100wt％的铝、铜、镍、铁、钛、银、金、钴、铬、钼和钨中的一种；
    其中，所述合金II中的金属选自铝、铜、镍、铁、钛、银、金、钴、铬、钼、钨、锰、镁和锌中的至少一种，所述合金II中的非金属选自硅和/或碳；优选地，所述合金II选自铝铜合金、铝锰合金、铝硅合金、铝镁合金、铝镁硅合金和铝锌合金中的至少一种；
    优选地，所述导电层I和导电层II的厚度分别独自选自0.1-2μm，优选为0.2-1.5μm；
    优选地，所述导电层I与聚合物层之间的结合力和所述聚合物层与导电层II之间的结合力均≥0.5N/15mm；
    优选地，所述导电层I和导电层II的电阻率均≤8μΩ·cm。
  5. 根据权利要求1-4中任意一项所述的负极集流体，其中，所述聚合物层的材料选自丙烯腈-丁二烯-苯乙烯共聚物、聚对苯二甲酸酯、聚对苯二甲酸丁二醇酯、聚对苯二甲酰对苯二胺、聚酰亚胺、聚酰胺、聚乙烯、聚苯乙烯、聚偏氟乙烯、聚氯乙烯、聚四氟乙烯、聚丙 乙烯、聚丙烯、聚碳酸酯、聚甲醛、环氧树脂和酚醛树脂中的至少一种；
    优选地，所述聚合物层的材料的抗拉强度≥150MPa，优选为150-400MPa；
    优选地，所述聚合物层的材料在150℃下处理30min后的热收缩率≤3％；
    优选地，所述聚合物层的厚度为1-15μm，优选为1-10μm。
  6. 根据权利要求1-5中任意一项所述的负极集流体，其中，所述负极集流体还包括中间层I和中间层II，其中，所述中间层I设置在阻挡层I和导电层I之间，所述中间层II设置在阻挡层II和导电层II之间；
    优选地，所述中间层I和中间层II的材料分别独立地选自单一金属III、合金III、氧化物半导体或导电化合物；
    其中，所述单一金属III选自Cu、Cr、Ta、Zn、Cd、In、Tl、Mn、Co、Mo、Fe、Sn、Ge、Bi、Sb、Re、Ti、V、Ni、Nb和Tc中的一种，优选选自Ti、V、Cr、Mn、Fe、Co、Ni和Cu中的一种；
    其中，所述合金III中的金属选自Cu、Cr、Ta、Zn、Cd、In、Tl、Mn、Co、Mo、Fe、Sn、Ge、Bi、Sb、Re、Ti、V、Ni、Nb和Tc中的至少一种，优选选自Ti、V、Cr、Mn、Fe、Co、Ni和Cu中的至少一种；
    其中，所述氧化物半导体选自Cu2O、ZnO、SnO2、Fe2O3、TiO2、ZrO2、Co2O3、WO3、In2O3、Al2O3和Fe3O4中的至少一种；
    其中，所述导电化合物选自TiB2、TiC、TiN、ZrB2、ZrC、ZrN、VB2、VC、VN、NbB2、NbC、NbN、TaB2、TaC、CrB2、Cr3C2、CrN、Mo2C、Mo2B5、W2B5、WC和LaB6中的至少一种；
    优选地，所述中间层I和中间层II分别独自为镍、镍基合金、铜基合金和氮化钛中的至少一种，优选为氮化钛；
    优选地，所述中间层I和中间层II的厚度分别独自地为1-1000nm，优选5-500nm。
  7. 根据权利要求1-6中任意一项所述的负极集流体，其中，所述负极集流体还包括粘结层I和粘结层II；其中，所述粘结层I设置在导电层I和聚合物层之间，所述粘结层II设置在导电层II和聚合物层之间；
    优选地，所述粘结层I和粘结层II的材料分别独立地选自乙基纤维素、亚甲基丁二酸、苯乙烯、羧甲基纤维素、胍基乙酸、异氰酸酯、聚氨酯、壳聚糖、聚己内酯和丁苯胶乳中的至少一种，以及任选的纳米二氧化硅、纳米三氧化二铝和氧化石墨烯中的至少一种；
    优选地，所述粘结层I和粘结层II的厚度分别独自地选自0.2-3μm，优选0.5-1μm。
  8. 根据权利要求7所述的负极集流体，其中，所述阻挡层I和阻挡层II的材料相同，所述导电层I和导电层II的材料相同；
    优选地，所述中间层I和中间层II的材料相同，所述粘结层I和粘结层II的材料相同。
  9. 一种负极集流体的制备方法，其特征在于，所述方法包括：先在聚合物层的上表面和下表面上分别制备导电层I和导电层II，之后再在所述导电层I上制备阻挡层I，在所述导电层II上制备阻挡层II；
    优选地，所述方法包括：先通过蒸镀在聚合物层的上表面和下表面上分别制备导电层I和导电层II，之后再通过蒸镀或溅射在所述导电层I上制备阻挡层I、在所述导电层II上制备阻挡层II；
    优选地，在通过蒸镀在聚合物层的上表面和下表面上制备导电层I和导电层II之前，通过涂覆在所述聚合物层的上表面和下表面分别制备粘结层I和粘结层II；
    优选地，在通过蒸镀或溅射在所述导电层I和导电层II上制备阻挡层I和阻挡层II之前，通过磁控溅射、反应溅射或活性反应蒸镀在所述导电层I上制备中间层I，在所述导电层II上制备中间层II；
    优选地，所述蒸镀为真空蒸镀，所述真空蒸镀的操作条件包括：真空度高于10-3Pa；冷辊温度为-25℃至35℃；ES距离≥50mm；蒸发温度≥800℃；
    优选地，所述磁控溅射的操作条件包括：真空度高于10-3Pa；主辊温度为-25℃至+35℃；主辊走速为20m/min以下；溅射功率为20kW以下；
    优选地，所述活性反应蒸镀的操作条件包括：真空度高于10-3Pa；冷辊温度为-25℃至35℃；ES距离≥50mm；蒸发温度≥400℃。
  10. 一种锂离子电池，其中，所述锂离子电池包括权利要求1-8中任意一项所述的负极集流体。
PCT/CN2023/140407 2022-12-23 2023-12-20 负极集流体及其制备方法和锂离子电池 WO2024131866A1 (zh)

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