Negative electrode current collector, its manufacturing method and lithium ion battery

Abstract

This application relates to the technical field of current collectors, specifically to a negative electrode current collector, a manufacturing method thereof, and a lithium ion battery. The negative electrode current collector includes, in order, a barrier layer I, a conductive layer I, a polymer layer, a conductive layer II, and a barrier layer II. In the negative electrode current collector according to this application, the barrier layers I and II have a continuous, dense film structure, which can prevent alloying of the conductive materials in the conductive layers I and II and improve the conductivity of the current collector. This allows it to replace the conventional copper negative electrode current collector and has the advantages of low production costs, high corrosion resistance, electrochemical stability, thin thickness, light weight, low conductivity, and high safety, making it suitable for industrial widespread use.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to a Chinese patent application filed with the China Patent Office on December 23, 2022, bearing application number "2022116650818" and titled "Negative electrode current collector and manufacturing method thereof and lithium ion battery," the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the technical field of current collectors, and more particularly to a negative electrode current collector and its manufacturing method, and a lithium ion battery. [Background technology]

[0003] Lithium-ion batteries generally use aluminum as the metal material for the positive electrode current collector and copper as the metal material for the negative electrode current collector. This is because aluminum metal has a high oxidation potential and the size of the vacancies in its lattice octahedron is similar to that of lithium. Therefore, aluminum easily reacts with lithium to form alloys such as LiAl, Li3Al2, and Li4Al3, which not only consumes a large amount of Li+ but also destroys the structure and morphology of the aluminum metal itself. Therefore, aluminum can be used as the current collector for the positive electrode of a lithium-ion battery, but cannot be used as the current collector for the negative electrode of a lithium-ion battery. Cu has very low lithium absorption capacity during the battery charge and discharge process, and maintains stable structure and electrochemical performance, so it can be used as the current collector for the negative electrode of a lithium-ion battery.

[0004] With the continuous development of lithium-ion battery technology, market demand is placing increasingly higher requirements on the energy density and weight of lithium-ion batteries. Therefore, future lithium-ion battery current collectors will develop toward thinner, lighter materials, higher electrical conductivity, and higher chemical and electrochemical stability. Because simple copper foils and aluminum foils are no longer able to meet market demand, researchers have begun researching and developing composite current collectors. However, current composite current collectors generally suffer from problems such as large mass, low mechanical strength, susceptibility to conductive layer shedding, susceptibility to corrosion by electrolyte, and low electrical conductivity.

[0005] Therefore, there is an urgent need to provide a negative electrode current collector that has advantages such as corrosion resistance, electrochemical stability, thin thickness, light weight, and high conductivity, and a method for producing the same. Summary of the Invention [Problem to be solved by the invention]

[0006] The purpose of the present application is to provide a negative electrode current collector, a manufacturing method thereof, and a lithium-ion battery, in order to overcome the problems of the negative electrode current collectors in the prior art, such as heavy mass, low mechanical strength, easy detachment of the conductive layer, easy corrosion by the electrolyte, and high resistivity. [Means for solving the problem]

[0007] To achieve the above object, a first aspect of the present application provides a negative electrode current collector including, in order, a barrier layer I, a conductive layer I, a polymer layer, a conductive layer II, and a barrier layer II.

[0008] A second aspect of the present application provides a method for manufacturing a negative electrode current collector, the method including first forming a conductive layer I and a conductive layer II on an upper surface and a lower surface of a polymer layer, respectively, and then forming a barrier layer I on the conductive layer I and a barrier layer II on the conductive layer II.

[0009] A third aspect of the present application provides a lithium ion battery including the negative electrode current collector according to the first aspect of the present application. [Effects of the Invention]

[0010] Through the above technical solution, the beneficial technical effects obtained by the present application are as follows: 1) The negative electrode current collector according to the present application can replace conventional copper foil as a negative electrode current collector, saving copper resources and costs and improving safety. 2) The negative electrode current collector according to the present application can reduce the tendency for galvanic corrosion and the degree of alloying of copper and aluminum by providing intermediate layer I and intermediate layer II, 3) The negative electrode current collector according to the present invention is provided with barrier layer I and barrier layer II, which can block the formation of Li-Al alloys and improve the electrical conductivity of the negative electrode current collector. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a first structural schematic diagram of a negative electrode current collector described in the present application. FIG. [Figure 2] FIG. 2 is a second structural schematic diagram of the negative electrode current collector described in the present application. [Figure 3] FIG. 2 is a third structural schematic diagram of the negative electrode current collector described in the present application. [Figure 4] FIG. 2 is a cross-sectional TEM image of the negative electrode current collector obtained in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0012] The endpoints of any ranges disclosed herein and any value should not be construed as limiting the range or value to that exact range or value, but rather as including values ​​close to that range or value. Numerical ranges between the endpoints of each range, between the endpoints of each range and any single point value, and between any single point value can be combined with each other to form one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0013] A first aspect of the present application provides a negative electrode current collector, which includes, in order, 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, as shown in FIG.

[0014] Here, in the present application, the barrier layer I 4 and the barrier layer II 5 have a continuous and dense film structure, which can prevent alloying of the conductive materials in the conductive layer I 2 and the conductive layer II 3, and can improve the conductivity of the current collector.

[0015] In one embodiment, 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.

[0016] In one preferred embodiment, the materials of the barrier layer I 4 and the barrier layer II 5 are each independently selected from a single metal I or an alloy I, where 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 ≥98 wt%, preferably 99-100 wt%, where 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. The alloy I further contains an optional non-metal, where the non-metal is selected from at least one of carbon, nitrogen, and silicon. Preferably, the alloy I is selected from at least one of copper-aluminum alloy, copper-nickel alloy, copper-zinc alloy, and gunmetal.

[0017] In one preferred embodiment, the thickness of the barrier layer I 4 and the barrier layer II 5 is independently selected from 1 to 1500 nm, for example, 1 nm, 10 nm, 100 nm, 500 nm, 800 nm, 1000 nm, 1200 nm, 1400 nm, 1500 nm, or any value between the aforementioned values, preferably 10 to 1000 nm.

[0018] In the present application, the role of the barrier layer is to prevent exposure of Al at the negative electrode terminal while at the same time providing a conductive function. The barrier layer in the present application is a continuous, dense film, and the barrier layer must not be too thin, otherwise it will interdiffuse with the conductive layer within a short period of time (days or weeks), exposing Al and losing its original function as a barrier layer. The barrier layer must also not be too thick, otherwise it will increase process costs, material utilization efficiency, etc., so the thickness of the barrier layer is preferably 10 to 1000 nm, more preferably 30 nm to 800 nm.

[0019] In one preferred embodiment, the bonding strength between the barrier layer I4 and the conductive layer I2, and the bonding strength between the conductive layer II3 and the barrier layer II5 are both ≧0.5 N / 15 mm, such as 0.5 N / 15 mm, 1 N / 15 mm, 2 N / 15 mm, 2.5 N / 15 mm, 3 N / 15 mm, 4 N / 15 mm, 6 N / 15 mm, 8 N / 15 mm, 10 N / 15 mm, 20 N / 15 mm, or any value between the aforementioned values.

[0020] Here, in this application, the bonding strength between barrier layer I 4 and conductive layer I 2, and the bonding strength between conductive layer II 3 and barrier layer II 5 are tested using a universal tensile tester, and the specific test method is based on the National Standard of the People's Republic of China GB / T 2792-2014 (Test method for peel strength of adhesive tape).

[0021] In one preferred embodiment, the materials of the conductive layer I2 and the conductive layer II3 are each 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 ≥ 98 wt%, preferably 99-100 wt%, 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 further comprises an optional non-metal, wherein the non-metal is selected from at least one of carbon, nitrogen, and silicon. Preferably, the alloy II is selected from at least one of an aluminum copper alloy, an aluminum manganese alloy, an aluminum silicon alloy, an aluminum magnesium alloy, an aluminum magnesium silicon alloy, and an aluminum zinc alloy.

[0022] In one preferred embodiment, the thickness of the conductive layer I2 and the conductive layer II3 is independently selected from 0.1 to 2 μm, for example, 0.1 μm, 0.2 μm, 0.3 μm, 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, or any value between the aforementioned values, preferably 0.2 to 1.5 μm.

[0023] In the present application, the conductive layer is a continuous film and has a conductive function. The conductive layer should not be too thin, otherwise the size effect of the metal film will be too large, resulting in a very high resistivity and affecting the internal resistance of the battery core. The conductive layer should not be too thick, otherwise it will increase process costs and material utilization efficiency. Therefore, the thickness of the conductive layer is preferably 0.2 to 1.5 μm. In one preferred embodiment, the bonding strength between the conductive layer I 2 and the polymer layer I and the bonding strength between the polymer layer I and the conductive layer II 3 are both ≧0.5 N / 15 mm, for example, 0.5 N / 15 mm, 1 N / 15 mm, 2 N / 15 mm, 2.5 N / 15 mm, 3 N / 15 mm, 4 N / 15 mm, 6 N / 15 mm, 8 N / 15 mm, 10 N / 15 mm, 20 N / 15 mm, or any value between the aforementioned values.

[0024] Here, in this application, the bonding strength between the conductive layer I 2 and the polymer layer 1, and the bonding strength between the polymer layer and the conductive layer II are tested using a universal tensile tester, and the specific test method is based on the National Standard of the People's Republic of China GB / T 2792-2014 (Test method for peel strength of adhesive tape).

[0025] In one preferred embodiment, the resistivity of the conductive layer I 2 and the conductive layer II 3 is ≦8 μΩ·cm, for example, 1 μΩ·cm, 2 μΩ·cm, 3 μΩ·cm, 4 μΩ·cm, 5 μΩ·cm, 6 μΩ·cm, 7 μΩ·cm, 8 μΩ·cm, or any value between the aforementioned values, preferably 2 to 5 μΩ·cm. In this application, the test method for resistivity refers to the US ASTM F390 (Standard Test Method for Measuring Sheet Resistance of Metal Films by Collinear Four-Probe Method).

[0026] In one preferred embodiment, the material of the polymer layer 1 is selected from at least one of acrylonitrile-butadiene-styrene copolymer (ABS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyparaphenylene terephthalamide (PPA), polyimide (PI), polyamide (PA), polyethylene (PE), polystyrene (PS), polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polytetrafluoroethylene, polyphenylene ether (PPE), polypropylene (PP), polycarbonate (PC), polyoxymethylene (POM), epoxy resin, and phenolic resin.

[0027] In one preferred embodiment, the thickness of the polymer layer 1 is 1 to 15 μm, preferably 1 to 10 μm.

[0028] In the present application, the thickness of the polymer layer can be reduced to improve the energy density of the battery, but if the thickness of the polymer layer is too small, the electrode plate is likely to break during processing. Through research, the inventors of the present application have found that when the thickness of the polymer layer is within the above-mentioned limited range, the processing performance and electrical performance of the negative electrode current collector are better.

[0029] In one preferred embodiment, the tensile strength of the polymer layer 1 material is ≥ 150 MPa, for example, 150 MPa, 180 MPa, 200 MPa, 250 MPa, 300 MPa, 400 MPa, 500 MPa, 600 MPa, or any value between the aforementioned values, preferably 150-400 MPa. Here, in this application, the polymer layer is the base of the negative electrode current collector and mainly plays a supporting role, ensuring the mechanical strength of the composite current collector and extending its service life. In this application, the tensile strength test refers to China's HG / T 2580-2008 (Determination of Tensile Strength and Elongation at Break of Rubber or Plastic Coated Fabrics).

[0030] In one preferred embodiment, the polymer layer 1 material has a heat shrinkage of ≦3% after 30 minutes at 150° C., preferably 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, or any value between the aforementioned values. Here, the test for heat shrinkage after 30 minutes at 150° C. refers to ASTM D-1204 (Standard Test Method for Linear Dimensional Change of Nonrigid Thermoplastic Sheet or Film at Elevated Temperature) specified by the American Society for Testing and Materials.

[0031] In one preferred embodiment, the materials of the barrier layer I 4 and the barrier layer II 5 are the same, and the materials of the conductive layer I 2 and the conductive layer II 3 are the same.

[0032] In one preferred embodiment, as shown in FIG. 2 , the negative electrode current collector further includes an intermediate layer I6 and an intermediate layer II7, where the intermediate layer I6 is disposed between the barrier layer I4 and the conductive layer I2, and the intermediate layer II7 is disposed between the barrier layer II5 and the conductive layer II3.

[0033] That is, in the present application, 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, i.e., the structure includes barrier layer I, intermediate layer I, conductive layer I, polymer layer, conductive layer II, intermediate layer II, and barrier layer II, in that order. Here, in the present application, the intermediate layer I and intermediate layer II can reduce the tendency for galvanic corrosion and the degree of alloying of copper and aluminum, thereby providing stability to the lithium ion battery.

[0034] In one preferred embodiment, the materials of the intermediate layer I 6 and the intermediate layer II 7 are each independently selected from a single metal III, an alloy III, an oxide semiconductor, or a conductive compound.

[0035] wherein 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; wherein 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, and preferably selected from at least one of Ti, V, Cr, Mn, Fe, Co, Ni, and Cu; wherein the oxide semiconductor is selected from at least one of Cu2O, ZnO, SnO2, Fe2O3, TiO2, ZrO2, Co2O3, WO3, In2O3, Al2O3, and Fe3O4; Here, 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.

[0036] In one preferred embodiment, the intermediate layer I and the intermediate layer II are each independently made of at least one of nickel, a nickel-based alloy, a copper-based alloy, and titanium nitride, and preferably titanium nitride.

[0037] In one preferred embodiment, the thicknesses of the intermediate layers I 6 and II 7 are each independently 1 to 1000 nm, e.g., 1 nm, 10 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, or any value between the aforementioned values, preferably 5 to 500 nm. Here, in the present application, when the thicknesses of the intermediate layers I 6 and II 7 are within the above-mentioned ranges, the corrosion resistance of the negative electrode current collector can be further improved and the degree of alloying of the conductive layer can be reduced.

[0038] In one preferred embodiment, as shown in FIG. 3 , the negative electrode current collector further includes an adhesive layer I8 and an adhesive layer II9, where the adhesive layer I8 is disposed between the conductive layer I2 and the polymer layer 1 and is used to connect the conductive layer I2 and the polymer layer 1, and the adhesive layer II9 is ​​disposed between the conductive layer II3 and the polymer layer 1 and is used to connect the conductive layer II3 and the polymer layer 1.

[0039] That is, in the present application, the negative electrode current collector may have a structure of barrier layer I-intermediate layer I-conductive layer I-adhesive layer I-polymer layer-adhesive layer II-conductive layer II-intermediate layer II-barrier layer II, i.e., it includes barrier layer I, intermediate layer I, conductive layer I, adhesive layer I, polymer layer, adhesive layer II, conductive layer II, intermediate layer II, and barrier layer II, in that order.

[0040] In one preferred embodiment, the materials of Adhesive Layer I 8 and Adhesive Layer II 9 are each 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 at least one of nanosilica, nano aluminum oxide, and graphene oxide.

[0041] In one preferred embodiment, the thickness of the adhesive layer I 8 and adhesive layer II 9 is independently selected from 0.2 to 3 μm, for example, 0.2 μm, 0.8 μm, 1 μm, 2 μm, 3 μm, or any value between the aforementioned values, preferably 0.5 to 1 μm.

[0042] In one preferred embodiment, the materials of the intermediate layer I 6 and the intermediate layer II 7 are the same, and the materials of the adhesive layer I 8 and the adhesive layer II 9 are the same.

[0043] Here, a lithium ion battery manufactured using the negative electrode current collector according to the present application has a relatively good cycle life, a relatively small polarization of the battery, a relatively small tendency to be corroded by the battery electrolyte, and a relatively high energy density by weight. This changes the conventional view that aluminum can only be used as a positive electrode current collector, and brings about a significant change and innovation in the current collector structure of lithium ion batteries, which is of great significance.

[0044] In one preferred embodiment, the corrosion rate of the negative electrode current collector is ≦0.5 mm / a. In this application, the corrosion resistance of the negative electrode current collector is tested as follows: at room temperature, a three-electrode system is used, 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 organic solution of lithium hexafluorophosphate (wherein the mass ratio of diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethylene carbonate (EC) is 1:1:1), and the Tafel curve of the negative electrode current collector is measured using an electrochemical workstation. The comparative sample is a conventional copper-aluminum foil current collector. The table shows the corrosion rates of the negative electrode current collector and the conventional copper-aluminum foil current collector.

[0045] A second aspect of the present application provides a method for manufacturing a negative electrode current collector, wherein the method includes first forming a conductive layer I and a conductive layer II on an upper surface and a lower surface of a polymer layer, respectively, and then forming a barrier layer I on the conductive layer I and a barrier layer II on the conductive layer II.

[0046] In one preferred embodiment, the method includes first fabricating a conductive layer I and a conductive layer II on the upper and lower surfaces of the polymer layer, respectively, by vapor deposition, and then fabricating a barrier layer I on the conductive layer I and a barrier layer II on the conductive layer II by vapor deposition or sputtering.

[0047] In one preferred embodiment, before forming conductive layers I and II on the upper and lower surfaces of polymer layer 1 by vapor deposition, adhesive layers I and II are formed by coating them on the upper and lower surfaces of the polymer layer, respectively.

[0048] In one preferred embodiment, before forming a barrier layer I and a barrier layer II on the conductive layer I and the conductive layer II by vapor deposition or sputtering, an intermediate layer I is formed on the conductive layer I by magnetron sputtering, reactive sputtering or activated reactive vapor deposition, and an intermediate layer II is formed on the conductive layer II.

[0049] In one preferred embodiment, the vapor deposition is vacuum deposition, and the operating conditions of the vacuum deposition include a vacuum degree higher than 10 Pa, a chill roll temperature of -25°C to 35°C, an ES distance of ≥ 50 mm, and an evaporation temperature of ≥ 800°C.

[0050] In one preferred embodiment, the operating conditions of the magnetron sputtering include a vacuum degree higher than 10 Pa, a main roll temperature of −25° C. to 35° C., a main roll running speed of 20 m / min or less, and a sputtering power of 20 kW or less.

[0051] In one preferred embodiment, the operating conditions of the activated reactive evaporation include a vacuum degree higher than 10 Pa, a chill roll temperature of -25°C to 35°C, an ES distance of ≥ 50 mm, and an evaporation temperature of ≥ 400°C.

[0052] The description of the degree of vacuum indicates the degree of gas thinning in a vacuum state, and the smaller the value, the thinner the gas and the higher the degree of vacuum.

[0053] In this application, the ES distance refers to the distance between the evaporation source and the substrate.

[0054] The evaporation source refers to a conductive metal material that is heated and evaporated in a vacuum deposition chamber, and the substrate refers to a pre-deposited film material, such as a polymer film.

[0055] In this application, when the intermediate layer I and the intermediate layer II are selected from titanium nitride, the manufacturing method of titanium nitride is activated reactive evaporation (ARE), that is, in the vacuum deposition coating process, a certain amount of activated reactive gas (e.g., 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 reactive gas, promoting the chemical reaction between them, and obtaining a compound plating layer on the surface of the workpiece.

[0056] The activated reactive deposition process can be carried out as follows.

[0057] The chamber was evacuated and the aluminum foil substrate was simultaneously baked to remove gas, maintaining a vacuum of 10 Pa or higher before deposition. The electron gun was turned on, the Ti plating material was melted and degassed, and N2 reactive gas was introduced through the needle valve. The baffle was opened, and a compound plating layer was obtained on the aluminum foil substrate.

[0058] A third aspect of the present application provides a lithium ion battery including the negative electrode current collector according to the first aspect of the present application.

[0059] In order to provide a better understanding of the present application, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the embodiments of the present application, and it is obvious that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments, and all other embodiments obtained by those skilled in the art based on the embodiments of the present application without any creative efforts fall within the scope of protection of the present application.

[0060] Unless otherwise specified, all reagents used in the examples of this application are commercially available products and can be purchased through commercial channels.

[0061] In the following examples and comparative examples, Thickness: GB / T 11378-2005 ((Metallic Coating Layer Thickness Measurement by Contour Meter Method) Sheet resistance / Resistivity: US ASTM F390 (Standard Test Method for Measuring the Sheet Resistance of Metallic Films by the Collinear Four-Probe Technique). Bond strength: GB / T 2792-2014 (Test method for peel strength of adhesive tape). Mechanical properties: 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). Heat shrinkage: GB / T 12027-2004 Experimental method for measuring the rate of dimensional change of plastic films and sheets due to heating

[0062] Test method for corrosion resistance of negative electrode composite current collector: At room temperature, a three-electrode system was used, the working electrode was the negative electrode current collector, the counter electrode was a platinum electrode, and the reference electrode was a non-mercury ion electrode. The electrolyte was a 1 mol / L organic solution of lithium hexafluorophosphate (wherein the mass ratio of diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethylene carbonate (EC) was 1:1:1). An electrochemical workstation was used to measure the metal foil sheet, and the Tafel curve of the metal platinum sheet was combined to calculate the corrosion resistance.

[0063] In this application, corrosion resistance is characterized by the corrosion rate, and the corrosion rate of the negative electrode composite current collector in this application is ≦0.1 mm / a.

[0064] Battery core manufacturing method: After applying the negative active material to the surface of the composite current collector and drying, the negative electrode winding is obtained. After being roll-pressed and punched, the positive and negative electrode plates are compacted and stacked in a Z-type laminator. The tabs are welded and packaged to obtain an unfilled battery core. After filling, the battery is aged and hot-pressed to activate the battery core, and then aged. Finally, the battery is packaged and obtained. [Example]

[0065] First, 1 μm of metallic Al was vacuum-deposited on each of the top and bottom surfaces of a 6 μm thick PET sheet, and then 300 nm of metallic Cu was deposited on each of the surfaces of the metallic Al.

[0066] The composite current collector after film formation was used as the negative electrode current collector, and a battery core was fabricated using the above process. The performance of the battery core was tested, and the electrochemical performance of the composite current collector material was characterized. The test results are shown in Tables 1 and 2. [Example]

[0067] First, 1 μm of metallic Al was vacuum-deposited on each of the top and bottom surfaces of a 6 μm thick PET sheet, and then 800 nm of metallic Cu was deposited on each of the Al surfaces.

[0068] The composite current collector after film formation was used as the negative electrode current collector, and a battery core was fabricated using the above process. The performance of the battery core was tested, and the electrochemical performance of the composite current collector material was characterized. The test results are shown in Tables 1 and 2.

[0069] FIG. 4 is a cross-sectional TEM image of the negative electrode current collector obtained in Example 2. As can be seen from FIG. 4, the thickness of the barrier layer is sufficiently dense and continuous to prevent the reaction of LiAl, and this structural material can be applied to negative electrode terminals. [Example]

[0070] First, 1 μm of metallic Al was vacuum-deposited on each of the top and bottom surfaces of a 6 μm thick PET sheet. Next, 30 nm of metallic Ni was deposited on each of the top and bottom surfaces of the Al by magnetron sputtering, and 300 nm of metallic Cu was vacuum-deposited on each of the top and bottom surfaces of the metallic Ni.

[0071] The composite current collector after film formation was used as the negative electrode current collector, and a battery core was fabricated using the above process. The performance of the battery core was tested, and the electrochemical performance of the composite current collector material was characterized. The test results are shown in Tables 1 and 2. [Example]

[0072] First, 1 μm of metallic Al was vacuum-deposited on each of the top and bottom surfaces of a 6 μm thick PET sheet. Next, 30 nm of metallic Ni was deposited on each of the Al surfaces by magnetron sputtering, and 800 nm of metallic Cu was vacuum-deposited on each of the top and bottom surfaces of the metallic Ni.

[0073] The composite current collector after film formation was used as the negative electrode current collector, and a battery core was fabricated using the above process. The performance of the battery core was tested, and the electrochemical performance of the composite current collector material was characterized. The test results are shown in Tables 1 and 2. [Example]

[0074] First, 1 μm of metallic Al was vacuum-deposited on each of the top and bottom surfaces of a 6 μm thick PET sheet. Next, 30 nm of the metal chemical TiN was deposited on each of the Al surfaces by activated reactive evaporation (ARE). Finally, 300 nm of metallic Cu was vacuum-deposited on each of the top and bottom surfaces of the metal compound TiN.

[0075] The composite current collector after film formation was used as the negative electrode current collector, and a battery core was fabricated using the above process. The performance of the battery core was tested, and the electrochemical performance of the composite current collector material was characterized. The test results are shown in Tables 1 and 2. [Example]

[0076] First, 1 μm of metallic Al was vacuum-deposited on each of the top and bottom surfaces of a 6 μm thick PET sheet. Next, 30 nm of the metal chemical TiN was deposited on each of the Al surfaces using activated reactive evaporation (ARE). Finally, 800 nm of metallic Cu was vacuum-deposited on each of the top and bottom surfaces of the metal compound TiN.

[0077] The composite current collector after film formation was used as the negative electrode current collector, and a battery core was fabricated using the above process. The performance of the battery core was tested, and the electrochemical performance of the composite current collector material was characterized. The test results are shown in Tables 1 and 2. [Example]

[0078] First, 1 μm of nanosilica-modified itaconic acid was applied to the top and bottom surfaces of 6 μm PET using a coater, followed by drying. 1 μm of metallic Al was vacuum-deposited onto the surface of each adhesive layer at once, and then 300 nm of metallic Cu was deposited onto the surface of the Al.

[0079] The composite current collector after film formation was used as the negative electrode current collector, and a battery core was fabricated using the above process. The performance of the battery core was tested, and the electrochemical performance of the composite current collector material was characterized. The test results are shown in Tables 1 and 2. [Example]

[0080] First, 1 μm of nanosilica-modified itaconic acid was applied to the top and bottom surfaces of 6 μm PET using a coater, followed by drying. 1 μm of metallic Al was vacuum-deposited onto the surface of each adhesive layer at once, and then 800 nm of metallic Cu was deposited onto the surface of the Al.

[0081] The composite current collector after film formation was used as the negative electrode current collector, and a battery core was fabricated using the above process. The performance of the battery core was tested, and the electrochemical performance of the composite current collector material was characterized. The test results are shown in Tables 1 and 2. [Example]

[0082] First, 1 μm of nanosilica-modified itaconic acid was applied to the top and bottom surfaces of 6 μm PET using a coater, followed by drying. 1 μm of metallic Al was vacuum-deposited onto the surface of each adhesive layer in one go. Next, 30 nm of metallic Ni was deposited onto the surface of the Al by magnetron sputtering, and then 300 nm of metallic Cu was deposited onto the surface of the metallic Ni in one go.

[0083] The composite current collector after film formation was used as the negative electrode current collector, and a battery core was fabricated using the above process. The performance of the battery core was tested, and the electrochemical performance of the composite current collector material was characterized. The test results are shown in Tables 1 and 2. [Example]

[0084] First, 1 μm of nanosilica-modified itaconic acid was applied to the top and bottom surfaces of 6 μm PET using a coater, followed by drying. 1 μm of metallic Al was vacuum-deposited onto the surface of each adhesive layer in one go. Next, 30 nm of metallic Ni was deposited onto the surface of the Al by magnetron sputtering, and then 800 nm of metallic Cu was deposited onto the surface of the metallic Ni in one go.

[0085] The composite current collector after film formation was used as the negative electrode current collector, and a battery core was fabricated using the above process. The performance of the battery core was tested, and the electrochemical performance of the composite current collector material was characterized. The test results are shown in Tables 1 and 2. [Example]

[0086] First, 1 μm of nanosilica-modified itaconic acid was applied to the top and bottom surfaces of 6 μm PET using a coater, and then dried. 1 μm of metallic Al was vacuum-deposited on the surface of each adhesive layer in one go, and then 30 nm of the metal chemical TiN was deposited on the surface of the Al using activated reactive evaporation (ARE), and then 300 nm of metallic Cu was deposited on the surface of the metal compound TiN in one go.

[0087] The composite current collector after film formation was used as the negative electrode current collector, and a battery core was fabricated using the above process. The performance of the battery core was tested, and the electrochemical performance of the composite current collector material was characterized. The test results are shown in Tables 1 and 2. [Example]

[0088] First, 1 μm of nanosilica-modified itaconic acid was applied to the top and bottom surfaces of 6 μm PET using a coater, followed by drying. 1 μm of metallic Al was vacuum-deposited onto the surface of each adhesive layer in one go. Next, 30 nm of the metal chemical TiN was deposited onto the surface of the Al using activated reactive evaporation (ARE). Finally, 800 nm of metallic Cu was deposited onto the surface of the metal compound TiN in one go.

[0089] The composite current collector after film formation was used as a negative electrode current collector, and a battery core was manufactured through the above process. The performance of the battery core was tested, and the electrochemical performance of the composite current collector material was characterized. The test results are shown in Tables 1 and 2. Comparative Example

[0090] 1 μm of metallic Al was directly vapor-deposited on the top and bottom surfaces of the 6 μm thick PET.

[0091] The composite current collector after film formation was used as the negative electrode current collector, and a battery core was fabricated using the above process. The performance of the battery core was tested, and the electrochemical performance of the composite current collector material was characterized. The test results are shown in Tables 1 and 2. JPEG2026502435000002.jpg84170JPEG2026502435000003.jpg75170

[0092] As can be seen from the results of the battery cores in Tables 1 and 2, those using Examples 1 to 12 of the present application have the ability to be used as negative electrode current collectors, which is a groundbreaking change in that Al cannot be used for negative electrodes.

[0093] Although the preferred embodiments of the present application have been described in detail above, the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including combining each technical feature in any other suitable manner, and these simple modifications and combinations should also be considered as the contents disclosed in the present application, and all fall within the protection scope of the present application. [Explanation of symbols]

[0094] 1 polymer layer 2 Conductive Layer I 3 Conductive layer II 4 Barrier Layer I 5 Barrier Layer II 6 Middle layer I 7 Middle layer II 8 Adhesive layer I 9 Adhesive layer II

Claims

1. 1. A negative electrode current collector, comprising, in order, a barrier layer I, a conductive layer I, a polymer layer, a conductive layer II, and a barrier layer II.

2. The negative electrode current collector according to claim 1 , wherein 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.

3. the materials of the barrier layer I and the barrier layer II are each independently selected from a single metal I or an alloy I; wherein the single metal I is selected from the group consisting of aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum, and tungsten; Preferably, said single metal I is selected from one of the following: aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum and tungsten, with a purity of ≥ 98 wt%, preferably with a purity of 99-100 wt%, 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; more preferably, the alloy I is selected from at least one of copper-aluminum alloy, copper-nickel alloy, copper-zinc alloy, and gunmetal; Preferably, the thickness of said barrier layer I and barrier layer II is independently selected from 1 to 1500 nm, preferably 10 to 1000 nm; 3. The negative electrode current collector according to claim 1, wherein a bonding strength between the barrier layer I and the conductive layer I and a bonding strength between the conductive layer II and the barrier layer II are both preferably ≧0.5 N / 15 mm.

4. the materials of the conductive layer I and the conductive layer II are each 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, said single metal II is selected from one of the following: aluminum, copper, nickel, iron, titanium, silver, gold, cobalt, chromium, molybdenum and tungsten, with a purity of ≥ 98 wt%, preferably with a purity of 99-100 wt%, 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 non-metal in the alloy II is selected from silicon and / or carbon; preferably, the alloy II is selected from at least one of aluminum-copper alloy, aluminum-manganese alloy, aluminum-silicon alloy, aluminum-magnesium alloy, aluminum-magnesium-silicon alloy, and aluminum-zinc alloy; Preferably, the thickness of the conductive layer I and the conductive layer II is independently selected from 0.1 to 2 μm, preferably 0.2 to 1.5 μm; Preferably, the bonding strength between the conductive layer I and the polymer layer and the bonding strength between the polymer layer and the conductive layer II are both ≧0.5 N / 15 mm; The negative electrode current collector according to claim 1 , wherein the resistivity of each of the conductive layers I and II is preferably ≦8 μΩ·cm.

5. a material of the polymer layer selected from at least one of acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate, polybutylene terephthalate, polyparaphenylene terephthalamide, polyimide, polyamide, polyethylene, polystyrene, polyvinylidene fluoride, polyvinyl chloride, polytetrafluoroethylene, polyphenylene ether, polypropylene, polycarbonate, polyoxymethylene, epoxy resin, and phenolic resin; Preferably, the tensile strength of the material of said polymer layer is ≧150 MPa, preferably 150-400 MPa; Preferably, the material of the polymer layer has a heat shrinkage rate of ≦3% after treatment at 150° C. for 30 minutes; The negative electrode current collector according to any one of claims 1 to 4, wherein the thickness of the polymer layer is preferably 1 to 15 µm, more preferably 1 to 10 µm.

6. the negative electrode current collector further includes an intermediate layer I and an intermediate layer II, wherein the intermediate layer I is disposed between the barrier layer I and the conductive layer I, and the intermediate layer II is disposed between the barrier layer II and the conductive layer II; Preferably, the materials of the intermediate layer I and the intermediate layer II are each independently selected from a single metal III, an alloy III, an oxide semiconductor, or a conductive compound; wherein 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; wherein 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, and preferably selected from at least one of Ti, V, Cr, Mn, Fe, Co, Ni, and Cu; wherein the oxide semiconductor is selected from at least one of Cu2O, ZnO, SnO2, Fe2O3, TiO2, ZrO2, Co2O3, WO3, In2O3, Al2O3, and Fe3O4; wherein 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; Preferably, the intermediate layer I and the intermediate layer II are each independently at least one of nickel, a nickel-based alloy, a copper-based alloy, and titanium nitride, and preferably titanium nitride; The negative electrode current collector according to any one of claims 1 to 5, wherein the thickness of the intermediate layer I and the intermediate layer II is preferably independently 1 to 1000 nm, more preferably 5 to 500 nm.

7. the negative electrode current collector further includes an adhesive layer I and an adhesive layer II, wherein the adhesive layer I is disposed between the conductive layer I and the polymer layer, and the adhesive layer II is disposed between the conductive layer II and the polymer layer; Preferably, the materials of the adhesive layer I and the adhesive layer II are each 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 at least one of nanosilica, nano aluminum oxide, and graphene oxide; The negative electrode current collector according to any one of claims 1 to 6, wherein the thicknesses of the adhesive layer I and the adhesive layer II are each independently selected from 0.2 to 3 µm, and preferably 0.5 to 1 µm.

8. the barrier layer I and the barrier layer II are made of the same material, the conductive layer I and the conductive layer II are made of the same material, The negative electrode current collector according to claim 7 , wherein the intermediate layer I and the intermediate layer II are preferably made of the same material, and the adhesive layer I and the adhesive layer II are preferably made of the same material.

9. A method for manufacturing a negative electrode current collector, the method comprising: first forming a conductive layer I and a conductive layer II on an upper surface and a lower surface of a polymer layer, respectively; thereafter forming a barrier layer I on the conductive layer I; and thereafter forming a barrier layer II on the conductive layer II; Preferably, the method comprises first producing a conductive layer I and a conductive layer II on the upper and lower surfaces of the polymer layer, respectively, by vapor deposition, and then producing a barrier layer I on the conductive layer I and a barrier layer II on the conductive layer II by vapor deposition or sputtering, Preferably, before producing the conductive layers I and II on the upper and lower surfaces of the polymer layer by vapor deposition, the adhesive layers I and II are produced by coating the upper and lower surfaces of the polymer layer, respectively; Preferably, before forming a barrier layer I and a barrier layer II on the conductive layer I and the conductive layer II by vapor deposition or sputtering, an intermediate layer I is formed on the conductive layer I by magnetron sputtering, reactive sputtering or activated reactive vapor deposition, and an intermediate layer II is formed on the conductive layer II; Preferably, the vapor deposition is vacuum deposition, and the operating conditions of the vacuum deposition include: a vacuum degree higher than 10 Pa; a chill roll temperature of −25° C. to 35° C.; an ES distance of ≧50 mm; and an evaporation temperature of ≧800° C.; Preferably, the operating conditions of the magnetron sputtering include a degree of vacuum higher than 10 Pa, a main roll temperature of −25° C. to +35° C., a main roll running speed of 20 m / min or less, and a sputtering output of 20 kW or less; Preferably, the operating conditions of the activated reactive vapor deposition include a degree of vacuum higher than 10 Pa, a chill roll temperature of −25° C. to 35° C., an ES distance of ≧50 mm, and an evaporation temperature of ≧400° C.

10. A lithium ion battery, wherein the lithium ion battery comprises the negative electrode current collector of any one of claims 1 to 8.

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