Novel distributed copper-aluminum composite current collector

Abstract

The invention relates to the technical field of batteries, in particular to a novel distributed copper-aluminum composite current collector. Plasma treatment is carried out on the polymer film, the surface energy of the film is improved through plasma activation, the reaction between the film and 3-aminopropyltrimethoxysilane is enhanced, and conditions are created for the subsequent grafting reaction of amino groups. After plasma treatment, the film is soaked in a solution containing amino silane, so that the amino silane reacts with functional groups on the surface of the film to form covalent bonds, and the amino groups are firmly grafted to the surface of the film. Titanium dioxide is added into the binder, so that the bonding strength of the binder is enhanced, then gaps among titanium dioxide are filled with boron nitride fibers, the boron nitride fibers and the titanium dioxide are loaded together through dopamine, the boron nitride fibers and the titanium dioxide have a synergistic effect, the bonding force between a metal layer and a polymer film is greatly enhanced, and the tensile strength of the film is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and specifically to a novel distributed copper-aluminum composite current collector. Background Art

[0002] Lithium batteries have the advantages of long recycling life, environmental protection and energy saving, and are an important energy storage technology. The current collector is one of the indispensable components in lithium batteries. The current collectors used in existing lithium batteries are pure copper foils for the negative electrode and pure aluminum foils for the positive electrode. Whether it is copper foil or aluminum foil, they are monomer materials, and there are some negative effects, such as higher process control requirements, increased costs or reduced energy density. Composite current collectors integrate the characteristics of being thin and light and having high safety, and have been widely studied in recent years. However, at present, only a single active material positive electrode material or negative electrode material is coated on the surface of the composite copper current collector or composite aluminum current collector, which limits the diversity of the structural design of lithium batteries and also limits the application of some advanced materials such as solid electrolytes. In addition, at present, the polymer film and the adhesive layer are not porous structures, which is not convenient for the movement of ions. Using a porous structure film as the polymer film layer can enhance the adhesion between the metal layer and the polymer film, but the tensile strength of the porous structure film is not high.

[0003] In order to solve the problems of poor adhesion and low tensile strength between the metal layer and the polymer film, the present invention provides a novel distributed copper-aluminum composite current collector. Summary of the Invention

[0004] The purpose of the present invention is to provide a novel distributed copper-aluminum composite current collector to solve the problems raised in the above background art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A novel distributed copper-aluminum composite current collector, which includes a polymer film, an adhesive layer, a copper layer, and an aluminum layer; the adhesive layer is attached to both sides of the polymer film; the copper layer and the aluminum layer are respectively attached to the polymer film through the adhesive layer.

[0007] Preferably, the adhesive layer is formed on the surface of the polymer film after coating, pressure lamination, and aging of the polyacrylic acid adhesive layer coating solution; the single-sided coating surface density of the polyacrylic acid adhesive layer coating solution is 0.1-10 g / m 2 .

[0008] Preferably, the thickness of the aluminum layer is 5-20 microns; the thickness of the copper layer is 2-15 microns.

[0009] Preferably, the preparation method of the polyacrylic acid adhesive layer coating solution includes the following steps:

[0010] Step 1: Take Tris solution, add hydrochloric acid, adjust the pH value to obtain a mixed solution; take anhydrous ethanol and the mixed solution, mix them evenly, add boron nitride fibers, ultrasonically disperse for 30 - 40 min, add dopamine hydrochloride, raise the temperature to 55 - 60 °C, stir for 3 - 4 h, add carboxylated titanium dioxide, stir for 1 - 2 h, add polyethylene glycol active ester, stir for 4 - 5 h, wash and dry to obtain a modified boron nitride - titanium dioxide composite;

[0011] Step 2: Take the modified boron nitride - titanium dioxide composite and polyacrylic acid binder, mix them and stir for 10 - 20 min, add sodium hydroxide, adjust the pH value, and stir for 20 - 30 min to obtain a polyacrylic acid binder layer coating solution.

[0012] Preferably, the preparation method of the carboxylated titanium dioxide is as follows: Take anhydrous ethanol and deionized water, stir them evenly, add γ - aminopropyltriethoxysilane, and stir evenly to obtain a γ - aminopropyltriethoxysilane mixed solution; take anhydrous ethanol and deionized water, stir them evenly, add titanium dioxide, ultrasonically disperse, add ammonia water to adjust the pH value to 7, stir evenly at 40 - 45 °C, raise the temperature to 60 - 65 °C, dropwise add the γ - aminopropyltriethoxysilane mixed solution, react for 4 - 5 h, centrifuge, wash, and dry to obtain amino - functionalized titanium dioxide; take the amino - functionalized titanium dioxide and anhydrous ethanol, ultrasonically disperse, add acrylic acid and glyoxal, react at 40 - 45 °C for 5 - 6 h, centrifuge, wash, and dry to obtain carboxylated titanium dioxide.

[0013] Preferably, in Step 2, add sodium hydroxide and adjust the pH value to 7.5 - 8.5.

[0014] A preparation method of a novel distributed copper - aluminum composite current collector includes the following steps:

[0015] S1: Take a polymer film, clean and dry it, then perform plasma treatment. Immerse the polymer film after plasma treatment in a 3 - aminopropyltrimethoxysilane solution at an immersion temperature of 70 - 80 °C for 30 - 40 min to obtain a polymer film with amino groups;

[0016] S2: Unroll and re - roll the polymer film, and coat the polyacrylic acid binder layer coating solution on the upper and lower surfaces respectively to form a binder layer;

[0017] S3: Take an aluminum sheet and a copper sheet, roll the aluminum sheet into an aluminum foil; roll the copper sheet into a copper foil; respectively compound the aluminum foil and the copper foil with a high - thermal - conductivity binder layer to form a copper layer and an aluminum layer, and then obtain a high - thermal - conductivity distributed copper - aluminum composite current collector through heat aging.

[0018] Preferably, in S1, the plasma treatment power is 30 - 60 W, and the plasma treatment time is 5 - 15 min; the polymer film is a BOPP film;

[0019] Preferably, in S1, the preparation method of the 3 - aminopropyltrimethoxysilane solution is: take anhydrous ethanol, 3 - aminopropyltrimethoxysilane, and sodium acetate - glacial acetic acid buffer solution, mix them evenly to obtain the 3 - aminopropyltrimethoxysilane solution.

[0020] Preferably, in S2, the unwinding tension is 50 - 200 N, and the winding tension is 50 - 200 N.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0022] (1) The present invention performs plasma treatment on the polymer film, activates the surface energy of the film through plasma to enhance the reaction between the film and 3 - aminopropyltrimethoxysilane, and creates conditions for the subsequent grafting reaction of amino groups. After plasma treatment, the film is immersed in a solution containing amino silane, so that the amino silane reacts with the functional groups on the film surface to form covalent bonds, thereby firmly grafting the amino groups onto the film surface.

[0023] (2) The present invention adds 2 - 3 μm of titanium dioxide to the binder to enhance the bonding strength of the binder, and then adds boron nitride fibers with a diameter of 20 - 60 nm to fill the gaps between the titanium dioxides, and loads the two together with dopamine. The two work together to greatly enhance the bonding force between the metal layer and the polymer film and improve the tensile strength of the film. At the same time, the titanium dioxide and boron nitride fibers can form a porous structure between the polymer film and the binder, facilitating the movement of ions.

[0024] In the process of preparing the modified boron nitride - titanium dioxide composite, the present invention also adds polyethylene glycol active ester to modify the composite. The polyethylene glycol active ester can form stable amide bonds with the amino groups on the polymer film at pH 7.5 - 8.5, greatly enhancing the bonding force between the metal layer and the polymer film. Detailed Embodiments

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] There are no special restrictions on the purchasing manufacturers of all the raw materials involved in the present invention. Exemplarily, they include: the polymer film is a BOPP film, which can be purchased from Zhejiang Great Southeast and has a thickness of 5 μm; boron nitride fiber: with a diameter of 20 - 60 nm, which can be purchased from the Boron Nitride Material Research Center of Hebei University of Technology; titanium dioxide: 2 - 3 μm, model: T832269, which can be purchased from Macklin; polyethylene glycol active ester: MW5000, which can be purchased from Sigma Corporation; polyacrylic acid binder: model SY - 302, which can be purchased from Sanying New Materials; polyethyleneimine: model UN - 2580, which can be purchased from Youen Chemical Industry; copper sheet: item number ZTD2018090T2, which can be purchased from Xinyie Metals; aluminum sheet: item number lp123tt, which can be purchased from Flex Insulation Building Materials.

[0027] Example 1: A novel distributed copper - aluminum composite current collector, comprising the following steps:

[0028] Step 1: Preparation of a polymer film with amino groups:

[0029] Take the polymer film BOPP film, clean and dry it, and then perform plasma treatment for 10 min with a plasma treatment power of 50 W;

[0030] Take 280 ml of absolute ethanol, 50 ml of 3 - aminopropyltrimethoxysilane, and 20 ml of sodium acetate - glacial acetic acid buffer solution with a pH value of 5, mix them evenly to obtain a 3 - aminopropyltrimethoxysilane solution;

[0031] Quickly put the plasma - treated polymer film into the 3 - aminopropyltrimethoxysilane solution for soaking at an immersion temperature of 75 °C for 35 min to obtain a polymer film with amino groups;

[0032] Step 2: Preparation of carboxylated titanium dioxide:

[0033] Take 135 mL of absolute ethanol, 15 mL of deionized water, stir evenly, add 0.5 g of γ - aminopropyltriethoxysilane, and stir for 55 min to obtain a γ - aminopropyltriethoxysilane mixture; take 64 mL of absolute ethanol, 16 mL of deionized water, stir evenly, add 1 g of titanium dioxide, ultrasonically disperse for 70 min, add ammonia water to adjust the pH value to 7, stir at 43 °C for 55 min, raise the temperature to 63 °C, dropwise add the γ - aminopropyltriethoxysilane mixture, react for 4.5 h, centrifuge, wash, and dry to obtain amino - functionalized titanium dioxide;

[0034] Take 1 g of amino - functionalized titanium dioxide, 100 mL of absolute ethanol, ultrasonically disperse for 50 min, add 0.3 g of acrylic acid and 0.4 g of glyoxal, react at 43 °C for 5.5 h, centrifuge, wash, and dry to obtain carboxylated titanium dioxide;

[0035] Step 3: Preparation of modified boron nitride-titanium dioxide composite:

[0036] Prepare a 10 mmol / L Tris solution, add hydrochloric acid, and adjust the pH value to 8.5 to obtain a mixed solution; take 100 mL of absolute ethanol and 350 mL of the mixed solution, mix them evenly, add 2 g of boron nitride fiber, disperse it by ultrasonic for 35 min, add 1 g of hydrochloric acid dopamine, raise the temperature to 58 °C, stir for 3.5 h, add 1.5 g of carboxylated titanium dioxide, stir for 1.5 h, add 2 g of polyethylene glycol active ester, stir for 4.5 h, wash and dry to obtain the modified boron nitride-titanium dioxide composite;

[0037] Step 4: Preparation of the bonding layer: By weight percentage, mix 18% of the modified boron nitride-titanium dioxide composite and 82% of the polyacrylic acid binder, stir for 15 min, add sodium hydroxide, adjust the pH value to 7.5, stir for 25 min to obtain the polyacrylic acid bonding layer coating solution, unwind and rewind the polymer film with amino groups; the unwinding tension is 100 N and the rewinding tension is 100 N; coat the polyacrylic acid bonding layer coating solution on the upper and lower surfaces respectively, and the single-sided coating surface density is 3 g / m 2 , to form the bonding layer;

[0038] Step 5: Preparation of the copper-aluminum composite current collector:

[0039] Take an aluminum sheet and a copper sheet, roll the aluminum sheet into an aluminum foil with a thickness of 6 μm; roll the copper sheet into a copper foil with a thickness of 6 μm; respectively compound the aluminum foil and the copper foil with the bonding layer, the compounding pressure is 1 MPa, the compounding temperature is 35 °C, and the compounding speed is 150 m / min; the aging temperature is 40 °C and the aging time is 20 s to obtain a 20-μm copper-aluminum composite current collector.

[0040] Example 2: A novel distributed copper-aluminum composite current collector, including the following steps:

[0041] Step 1: Preparation of the polymer film with amino groups:

[0042] Take the polymer film BOPP film, clean and dry it, and then perform plasma treatment for 5 min, and the plasma treatment power is 60 W;

[0043] Take 280 ml of absolute ethanol, 50 ml of 3-aminopropyltrimethoxysilane, and 20 ml of sodium acetate-acetic acid buffer solution with a pH value of 5, mix them evenly to obtain a 3-aminopropyltrimethoxysilane solution;

[0044] Quickly put the plasma-treated polymer film into the 3-aminopropyltrimethoxysilane solution and soak it, the soaking temperature is 80 °C, and soak for 30 min to obtain the polymer film with amino groups;

[0045] Step 2: Preparation of carboxylated titanium dioxide:

[0046] Take 135 mL of absolute ethanol and 15 mL of deionized water, stir evenly, add 0.5 g of γ-aminopropyltriethoxysilane, and stir for 50 min to obtain a γ-aminopropyltriethoxysilane mixed solution; take 64 mL of absolute ethanol and 16 mL of deionized water, stir evenly, add 1 g of titanium dioxide, ultrasonically disperse for 60 min, add ammonia water to adjust the pH value to 7, stir at 40 °C for 50 min, raise the temperature to 60 °C, dropwise add the γ-aminopropyltriethoxysilane mixed solution, react for 4 h, centrifuge, wash, and dry to obtain amino-functionalized titanium dioxide;

[0047] Take 1 g of amino-functionalized titanium dioxide and 100 mL of absolute ethanol, ultrasonically disperse for 40 min, add 0.3 g of acrylic acid and 0.4 g of glyoxal, react at 40 °C for 5 h, centrifuge, wash, and dry to obtain carboxylated titanium dioxide;

[0048] Step 3: Preparation of modified boron nitride-titanium dioxide composite:

[0049] Prepare a 10 mmol / L Tris solution, add hydrochloric acid to adjust the pH value to 8.5 to obtain a mixed solution; take 100 mL of absolute ethanol and 350 mL of the mixed solution, mix evenly, add 2 g of boron nitride fibers, ultrasonically disperse for 30 min, add 1 g of hydrochloric acid dopamine, raise the temperature to 55 °C, stir for 3 h, add 1.5 g of carboxylated titanium dioxide, stir for 1 h, add 2 g of polyethylene glycol active ester, stir for 4 h, wash, and dry to obtain a modified boron nitride-titanium dioxide composite;

[0050] Step 4: Preparation of the adhesive layer: By weight percentage, mix 18% of the modified boron nitride-titanium dioxide composite and 82% of the polyacrylic acid binder, stir for 10 min, add sodium hydroxide to adjust the pH value to 7.5, stir for 20 min to obtain a polyacrylic acid adhesive layer coating solution, unwind and rewind a polymer film with amino groups; the unwind tension is 120 N, and the rewind tension is 120 N; coat the polyacrylic acid adhesive layer coating solution on the upper and lower surfaces respectively, and the single-sided coating surface density is 3 g / m 2 , to form an adhesive layer;

[0051] Step 5: Preparation of the copper-aluminum composite current collector:

[0052] Take aluminum sheets and copper sheets, roll the aluminum sheets into aluminum foils with a thickness of 6 μm; roll the copper sheets into copper foils with a thickness of 6 μm; respectively laminate the aluminum foils and copper foils with the adhesive layer, the lamination pressure is 0.5 MPa, the lamination temperature is 30 °C, and the lamination speed is 100 m / min; the aging temperature is 35 °C, and the aging time is 30 s to obtain a 20-μm copper-aluminum composite current collector.

[0053] Example 3: A new type of distributed copper-aluminum composite current collector, comprising the following steps:

[0054] Step 1: Preparation of a polymer film with amino groups:

[0055] Take the polymer film BOPP film, clean and dry it, and then perform plasma treatment for 15 minutes with a plasma treatment power of 30 W;

[0056] Take 280 ml of absolute ethanol, 50 ml of 3-aminopropyltrimethoxysilane, and 20 ml of sodium acetate-acetic acid buffer solution with a pH value of 5, mix them evenly to obtain a 3-aminopropyltrimethoxysilane solution;

[0057] Quickly put the plasma-treated polymer film into the 3-aminopropyltrimethoxysilane solution and soak it at a soaking temperature of 70 °C for 40 minutes to obtain a polymer film with amino groups;

[0058] Step 2: Preparation of carboxylated titanium dioxide:

[0059] Take 135 mL of absolute ethanol and 15 mL of deionized water, stir evenly, add 0.5 g of γ-aminopropyltriethoxysilane, and stir for 60 minutes to obtain a γ-aminopropyltriethoxysilane mixture; take 64 mL of absolute ethanol and 16 mL of deionized water, stir evenly, add 1 g of titanium dioxide, ultrasonically disperse for 90 minutes, add ammonia water to adjust the pH value to 7, stir at 45 °C for 60 minutes, raise the temperature to 65 °C, dropwise add the γ-aminopropyltriethoxysilane mixture, react for 5 hours, centrifuge, wash, and dry to obtain amino-functionalized titanium dioxide;

[0060] Take 1 g of amino-functionalized titanium dioxide and 100 mL of absolute ethanol, ultrasonically disperse for 60 minutes, add 0.3 g of acrylic acid and 0.4 g of glyoxal, react at 45 °C for 6 hours, centrifuge, wash, and dry to obtain carboxylated titanium dioxide;

[0061] Step 3: Preparation of modified boron nitride-titanium dioxide composite:

[0062] Prepare a 10 mmol / L Tris solution, add hydrochloric acid to adjust the pH value to 8.5 to obtain a mixed solution; take 100 mL of absolute ethanol and 350 mL of the mixed solution, mix them evenly, add 2 g of boron nitride fiber, ultrasonically disperse for 40 minutes, add 1 g of hydrochloric acid dopamine, raise the temperature to 60 °C, stir for 4 hours, add 1.5 g of carboxylated titanium dioxide, stir for 2 hours, add 2 g of polyethylene glycol active ester, stir for 5 hours, wash, and dry to obtain a modified boron nitride-titanium dioxide composite;

[0063] Step 4: Preparation of the bonding layer: By weight percentage, mix 18% of the modified boron nitride-titanium dioxide composite and 82% of the polyacrylic acid binder, stir for 20 min, add sodium hydroxide, adjust the pH value to 8, and stir for 30 min to obtain the polyacrylic acid bonding layer coating solution. Unwind and rewind the polymer film with amino groups; the unwinding tension is 200 N, and the rewinding tension is 200 N; Coat the polyacrylic acid bonding layer coating solution on the upper and lower surfaces respectively, and the single-sided coating areal density is 3 g / m 2 , to form the bonding layer;

[0064] Step 5: Preparation of the copper-aluminum composite current collector:

[0065] Take an aluminum sheet and a copper sheet, roll the aluminum sheet into an aluminum foil with a thickness of 6 μm; roll the copper sheet into a copper foil with a thickness of 6 μm; Composite the aluminum foil and the copper foil with the bonding layer respectively, the composite pressure is 1.5 MPa, the composite temperature is 40 °C, and the composite speed is 200 m / min; The aging temperature is 50 °C and the aging time is 30 s to obtain a 20-μm copper-aluminum composite current collector.

[0066] Comparative Example 1: A novel distributed copper-aluminum composite current collector, without pre-treating the polymer film BOPP film, and the rest is the same as in Example 1:

[0067] Step 1: Preparation of carboxylated titanium dioxide:

[0068] Take 135 mL of absolute ethanol and 15 mL of deionized water, stir evenly, add 0.5 g of γ-aminopropyltriethoxysilane, and stir for 55 min to obtain a γ-aminopropyltriethoxysilane mixed solution; Take 64 mL of absolute ethanol and 16 mL of deionized water, stir evenly, add 1 g of titanium dioxide, ultrasonically disperse for 70 min, add ammonia water to adjust the pH value to 7, stir at 43 °C for 55 min, raise the temperature to 63 °C, and dropwise add the γ-aminopropyltriethoxysilane mixed solution, react for 4.5 h, centrifuge, wash, and dry to obtain amino-functionalized titanium dioxide;

[0069] Take 1 g of amino-functionalized titanium dioxide and 100 mL of absolute ethanol, ultrasonically disperse for 50 min, add 0.3 g of acrylic acid and 0.4 g of glyoxal, react at 43 °C for 5.5 h, centrifuge, wash, and dry to obtain carboxylated titanium dioxide;

[0070] Step 2: Preparation of the modified boron nitride-titanium dioxide composite:

[0071] Prepare a 10 mmol / L Tris solution, add hydrochloric acid, and adjust the pH value to 8.5 to obtain a mixed solution; take 100 mL of absolute ethanol and 350 mL of the mixed solution, mix them evenly, add 2 g of boron nitride fibers, disperse them by ultrasonic for 35 min, add 1 g of dopamine hydrochloride, heat up to 58 °C, stir for 3.5 h, add 1.5 g of carboxylated titanium dioxide, stir for 1.5 h, add 2 g of polyethylene glycol active ester, stir for 4.5 h, wash and dry to obtain a modified boron nitride-titanium dioxide composite;

[0072] Step 3: Preparation of the bonding layer: By weight percentage, mix 18% of the modified boron nitride-titanium dioxide composite and 82% of the polyacrylic acid binder, stir for 15 min, add sodium hydroxide, adjust the pH value to 7.5, and stir for 25 min to obtain a polyacrylic acid bonding layer coating solution. Unroll and rewind the polymer film with amino groups; the unrolling tension is 100 N, and the rewinding tension is 100 N; coat the polyacrylic acid bonding layer coating solution on both the upper and lower surfaces respectively, and the single-sided coating surface density is 3 g / m 2 , to form a bonding layer;

[0073] Step 4: Preparation of the copper-aluminum composite current collector:

[0074] Take an aluminum sheet and a copper sheet, roll the aluminum sheet into an aluminum foil with a thickness of 6 μm; roll the copper sheet into a copper foil with a thickness of 6 μm; respectively laminate the aluminum foil and the copper foil with the bonding layer, the lamination pressure is 1 MPa, the lamination temperature is 35 °C, and the lamination speed is 150 m / min; the aging temperature is 60 °C, and the aging time is 20 s to obtain a 20-μm copper-aluminum composite current collector.

[0075] Comparative Example 2: A new type of distributed copper-aluminum composite current collector, without adding boron nitride, and the rest is the same as in Example 1:

[0076] Step 1: Preparation of the polymer film with amino groups:

[0077] Take the polymer film BOPP film, clean and dry it, and then perform plasma treatment for 10 min, and the plasma treatment power is 50 W;

[0078] Take 280 ml of absolute ethanol, 50 ml of 3-aminopropyltrimethoxysilane, and 20 ml of sodium acetate-acetic acid buffer solution with a pH value of 5, mix them evenly to obtain a 3-aminopropyltrimethoxysilane solution;

[0079] Quickly put the polymer film treated with plasma into the 3-aminopropyltrimethoxysilane solution and soak it, the soaking temperature is 75 °C, and soak for 35 min to obtain a polymer film with amino groups;

[0080] Step 2: Preparation of carboxylated titanium dioxide:

[0081] Take 135 mL of absolute ethanol and 15 mL of deionized water, stir evenly, add 0.5 g of γ-aminopropyltriethoxysilane, and stir for 55 min to obtain a γ-aminopropyltriethoxysilane mixture; take 64 mL of absolute ethanol and 16 mL of deionized water, stir evenly, add 1 g of titanium dioxide, ultrasonically disperse for 70 min, add ammonia water to adjust the pH value to 7, stir at 43 °C for 55 min, raise the temperature to 63 °C, dropwise add the γ-aminopropyltriethoxysilane mixture, react for 4.5 h, centrifuge, wash, and dry to obtain amino-functionalized titanium dioxide;

[0082] Take 1 g of amino-functionalized titanium dioxide and 100 mL of absolute ethanol, ultrasonically disperse for 50 min, add 0.3 g of acrylic acid and 0.4 g of glyoxal, react at 43 °C for 5.5 h, centrifuge, wash, and dry to obtain carboxyl-functionalized titanium dioxide;

[0083] Step 3: Preparation of modified titanium dioxide:

[0084] Take 100 mL of absolute ethanol, add 1.5 g of carboxyl-functionalized titanium dioxide, ultrasonically disperse for 35 min, raise the temperature to 58 °C, add 2 g of polyethylene glycol active ester, stir for 4.5 h, wash, and dry to obtain modified titanium dioxide;

[0085] Step 4: Preparation of the adhesive layer: By weight percentage, mix 18% of modified titanium dioxide and 82% of polyacrylic acid binder, stir for 15 min, add sodium hydroxide, adjust the pH value to 7.5, stir for 25 min to obtain a polyacrylic acid adhesive layer coating solution, unwind and rewind a polymer film with amino groups; the unwind tension is 100 N, and the rewind tension is 100 N; coat the polyacrylic acid adhesive layer coating solution on the upper and lower surfaces respectively, and the single-sided coating surface density is 3 g / m 2 , to form an adhesive layer;

[0086] Step 5: Preparation of the copper-aluminum composite current collector:

[0087] Take an aluminum sheet and a copper sheet, roll the aluminum sheet into an aluminum foil with a thickness of 6 μm; roll the copper sheet into a copper foil with a thickness of 6 μm; respectively compound the aluminum foil and the copper foil with the adhesive layer, the compounding pressure is 1 MPa, the compounding temperature is 35 °C, and the compounding speed is 150 m / min; the aging temperature is 60 °C, and the aging time is 20 s to obtain a 20-μm copper-aluminum composite current collector.

[0088] Experiment:

[0089] The copper-aluminum composite current collectors prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests. The two ends of a tensile testing machine were used to fix the samples; the tensile testing machine was started, and the samples were stretched. When fracture occurred, the recorded data was the tensile strength. The two ends of a tensile testing machine were used to fix the samples; the tensile testing machine was started to conduct a tensile test on the samples, and the length L0 between the upper and lower clamps before the test was set to 50 mm. The samples were stretched at a tensile speed of 100 mm / min until the distance between the two clamps when the sample was just broken was recorded as L1. Then the elongation of the sample = (L1 - L0) / L0. The polyacrylic acid adhesive layer coating solutions prepared in Examples 1-3 and Comparative Examples 1-2 were taken and respectively coated on the polymer films with amino groups and the untreated polymer films prepared in Examples 1-3 and Comparative Examples 1-2, and dried to form films. The coating thickness was 2 μm. A QFH-A film scribing tool was used to conduct an adhesion test on the polyacrylic acid adhesive layer coating solution film layer on the surface of the polymer film. First, 5 parallel incisions 15 mm long were made on the polyacrylic acid adhesive layer coating solution film layer, and the distance between each incision was 1 mm. Then a vertical incision was made on the parallel incisions, and the depth of the incisions was greater than the film thickness. The degree of peeling of the polyacrylic acid adhesive layer coating solution film layer was observed to characterize the adhesion between the polyacrylic acid adhesive layer coating solution and the polymer film. The obtained data is shown in the following table: The test results are shown in the following table:

[0090]

[0091] Conclusion: It can be seen from the comparison of the data in the table that in Comparative Example 1, the polymer film BOPP film was not pretreated, and there were no grafted amino groups on the film, so it was impossible to form stable amide bonds with polyethylene glycol active esters, and the film layer peeled off, with a peeling rate of 50%-65%, and the adhesion between the polyacrylic acid adhesive layer coating solution and the polymer film became poor. In Comparative Example 2, boron nitride was not added, the adhesion became poor, and the tensile strength of the film decreased.

[0092] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A novel distributed copper-aluminum composite current collector, Characterized in that: The novel distributed copper-aluminum composite current collector includes a polymer film, an adhesive layer, a copper layer, and an aluminum layer; the adhesive layer is attached to both sides of the polymer film; the copper layer and the aluminum layer are respectively adhered to the polymer film through the adhesive layer.

2. The novel distributed copper-aluminum composite current collector according to claim 1, Characterized in that: The adhesive layer is formed on the surface of the polymer film after coating, pressure lamination, and aging of the polyacrylic acid adhesive layer coating solution; the single-sided coating surface density of the polyacrylic acid adhesive layer coating solution is 0.1-10 g / m 2 .

3. The novel distributed copper-aluminum composite current collector according to claim 1, Characterized in that: The thickness of the aluminum layer is 5-20 microns; the thickness of the copper layer is 2-15 microns.

4. The novel distributed copper-aluminum composite current collector according to claim 2, Characterized in that: The preparation method of the polyacrylic acid adhesive layer coating solution includes the following steps: Step 1: Take a Tris solution, add hydrochloric acid, adjust the pH value to obtain a mixed solution; take anhydrous ethanol and the mixed solution, mix them evenly, add boron nitride fibers, ultrasonically disperse for 30-40 min, add dopamine hydrochloride, raise the temperature to 55-60 °C, stir for 3-4 h, add carboxylated titanium dioxide, stir for 1-2 h, add polyethylene glycol active ester, stir for 4-5 h, wash and dry to obtain a modified boron nitride-titanium dioxide composite; Step 2: Take the modified boron nitride-titanium dioxide composite and a polyacrylic acid binder, mix and stir for 10-20 min, add sodium hydroxide, adjust the pH value, and stir for 20-30 min to obtain a polyacrylic acid adhesive layer coating solution.

5. The novel distributed copper-aluminum composite current collector according to claim 4, Characterized in that: The preparation method of the carboxylated titanium dioxide is as follows: Take anhydrous ethanol and deionized water, stir evenly, add γ-aminopropyltriethoxysilane, stir evenly to obtain a γ-aminopropyltriethoxysilane mixed solution; take anhydrous ethanol and deionized water, stir evenly, add titanium dioxide, ultrasonically disperse, add ammonia water to adjust the pH value to 7, stir evenly at 40-45 °C, raise the temperature to 60-65 °C, dropwise add the γ-aminopropyltriethoxysilane mixed solution, react for 4-5 h, centrifuge, wash and dry to obtain amino-functionalized titanium dioxide; take the amino-functionalized titanium dioxide and anhydrous ethanol, ultrasonically disperse, add acrylic acid and glyoxal, react at 40-45 °C for 5-6 h, centrifuge, wash and dry to obtain carboxylated titanium dioxide.

6. The novel distributed copper-aluminum composite current collector according to claim 4, Characterized in that: In step 2, add sodium hydroxide and adjust the pH value to 7.5-8.

5.

7. A preparation method of a novel distributed copper-aluminum composite current collector, Characterized in that: Includes the following steps: S1: Take a polymer film, clean and dry it, then perform plasma treatment, immerse the polymer film treated with plasma in a 3-aminopropyltrimethoxysilane solution, the immersion temperature is 70-80 °C, and the immersion time is 30-40 min to obtain a polymer film with amino groups; S2: Unroll and rewind the polymer film, and coat the polyacrylic acid adhesive layer coating solution on the upper and lower surfaces respectively to form an adhesive layer; S3: Take aluminum sheets and copper sheets, roll the aluminum sheets into aluminum foils; roll the copper sheets into copper foils; respectively compound the aluminum foils and copper foils with a high thermal conductivity adhesive layer to form a copper layer and an aluminum layer, and then obtain a high thermal conductivity distributed copper-aluminum composite current collector through heat aging.

8. A novel distributed copper-aluminum composite current collector according to claim 7, characterized in that: In S1, the plasma treatment power is 30 - 60 W, and the plasma treatment time is 5 - 15 min; the polymer film is a BOPP film.

9. A novel distributed copper-aluminum composite current collector according to claim 7, characterized in that: In S1, the preparation method of the 3-aminopropyltrimethoxysilane solution is: take anhydrous ethanol, 3-aminopropyltrimethoxysilane, and sodium acetate-acetic acid buffer solution, mix them evenly to obtain the 3-aminopropyltrimethoxysilane solution.

10. A novel distributed copper-aluminum composite current collector according to claim 7, characterized in that: In S2, the unwind tension is 50 - 200 N, and the rewind tension is 50 - 200 N.

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