Large-scale preparation method of electrochemical anode based on graphene film encapsulation

Abstract

This invention provides a method for large-scale preparation of electrochemical anodes based on graphene film encapsulation, comprising: placing a multilayer graphene / initial substrate composite structure in an etching solution to etch the initial substrate, obtaining a multilayer graphene film; transferring the multilayer graphene film to a cleaning solution for rinsing by rolling; and bonding the target substrate to the upper surface of the rinsed multilayer graphene film by rolling, thereby obtaining an electrochemical anode encapsulated in graphene film. This invention also provides a transfer preparation apparatus, including a first unwinding roller, an etching tank, a cleaning tank, a second unwinding roller, a bonding roller, and a take-up roller. This invention can solve the technical problem of complex processes in the prior art for large-scale preparation of electrochemical anodes using LB films.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage technology, specifically to a method for large-scale preparation of electrochemical anodes based on graphene film encapsulation. Background Technology

[0002] As non-renewable energy sources such as oil and natural gas become increasingly scarce, the demand for renewable energy is growing, which is driving the development of safe, stable, low-cost, and environmentally friendly electrochemical energy storage systems.

[0003] In electrochemical energy storage systems, zinc is used as an example of the material for preparing the anode. Zinc is an inexpensive and abundant metal with a high volumetric capacity (5855 mAh cm⁻¹). -3 Due to its low redox potential (-0.76V compared to the standard hydrogen electrode), aqueous zinc-ion batteries (AZIBs) are considered the most promising candidate for next-generation energy storage devices. However, in practical applications, the poor reversibility of the zinc anode significantly impacts electrochemical performance, primarily due to dendrite growth in zinc metal. This non-uniform dendrite growth severely disrupts the stability of the electrode / electrolyte interface, accelerates side reactions, and ultimately reduces electrochemical performance.

[0004] To address the aforementioned technical challenges in dendrite growth, the Langmuir-Blodgett (LB) method is commonly used for one-step synthesis of nitrogen-doped graphene oxide (NGO) artificial interface films. This method achieves a parallel ultrathin interface modification layer (≈120 nm) on zinc foil to improve zinc dendrite growth. However, using this method, during the preparation process, due to the beneficial zinc affinity of the parallel graphene layers and nitrogen (N) doped groups, zinc crystals are uniformly deposited in a directional manner on the graphene plane. Furthermore, because the adhesion of the LB film to the substrate relies on intermolecular forces, which are physical bonds, the film's mechanical properties are relatively poor. Moreover, to obtain a neatly arranged and ordered LB film, the material must contain amphoteric groups, which poses a challenge to the design of LB film-forming materials. Simultaneously, the equipment for LB film fabrication is expensive, and the fabrication process requires highly sophisticated technology, which significantly hinders the large-scale fabrication of electrochemical anodes.

[0005] Therefore, there is an urgent need for a simple and easy-to-implement method for large-scale preparation of electrochemical anodes. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention proposes a method for large-scale preparation of electrochemical anodes based on graphene film encapsulation, thereby solving the technical problem of complex processes in the large-scale preparation of electrochemical anodes using LB films in existing technologies.

[0007] The technical solution adopted in this invention is as follows:

[0008] In one aspect, a method for large-scale preparation of electrochemical anodes based on graphene film encapsulation is provided, comprising the following steps:

[0009] The multilayer graphene / initial substrate composite structure was placed in an etching solution to etch the initial substrate, thereby obtaining a multilayer graphene film.

[0010] The multilayer graphene film is transferred to the cleaning solution by rolling it up for rinsing.

[0011] The target substrate is rolled up and bonded to the upper surface of a rinsed multilayer graphene film to obtain an electrochemical anode encapsulated in graphene film.

[0012] Furthermore, the multilayer graphene / initial substrate composite structure was prepared by chemical vapor deposition.

[0013] Furthermore, the initial substrate comprises copper, nickel, or a copper-nickel alloy; when the initial substrate is copper, the etching solution comprises FeCl3 solution or (NH4)2S2O8 solution; when the initial substrate is nickel or a copper-nickel alloy, the etching solution comprises (NH4)2S2O8 solution.

[0014] Furthermore, the multilayer graphene film has 3-6 layers.

[0015] Furthermore, the cleaning solution includes deionized water, ethanol, or chloroform.

[0016] Furthermore, the target substrate includes zinc or aluminum.

[0017] In a second aspect, an electrochemical anode preparation apparatus based on graphene film encapsulation is provided for implementing the preparation method described in the first aspect, comprising:

[0018] The first unwinding roll has a multilayer graphene / initial substrate composite structure wound on it;

[0019] An etching tank is located below the first unwinding roller; the etching tank is filled with etching liquid, and the gap between the upper surface of the etching liquid and the bottom of the first unwinding roller is not less than the thickness of the multilayer graphene / initial substrate composite structure.

[0020] A cleaning tank containing a cleaning solution;

[0021] The second unwinding roll has the target substrate wound on it.

[0022] A bonding roller is positioned above the tail end of the cleaning tank, and the gap between the upper surface of the cleaning liquid and the bottom of the bonding roller is no greater than the sum of the thicknesses of the multilayer graphene film and the target substrate; and

[0023] The take-up roller, by means of rotation, winds up the electrochemical anode wrapped with a graphene film obtained at the bonding roller.

[0024] Furthermore, it also includes a conveyor roller, which is located between the etching tank and the cleaning tank, and drives the multilayer graphene film to move into the cleaning tank by rotation.

[0025] Furthermore, it also includes a drying device, which is located between the bonding roller and the take-up roller.

[0026] Thirdly, an electrochemical anode based on graphene film encapsulation is provided, which is prepared using the method described in the first aspect.

[0027] As can be seen from the above technical solution, the beneficial technical effects of the present invention are as follows:

[0028] 1. Multilayer graphene films are directly bonded to target zinc or aluminum substrates via self-suspension and transport. This processing method is simple and easy to implement, enabling large-scale applications and providing a wider range of substrate options, allowing bonding to be achieved with any object of a fixed shape.

[0029] 2. The multilayer graphene film makes the zinc foil surface smoother, which can reduce the tip effect and avoid the formation of dendrites due to uneven growth of zinc ions during the deposition process.

[0030] 3. In the process of preparing the electrochemical anode, no additional protective film is required. A multilayer graphene film can be directly bonded to the zinc foil using a self-suspending method, thus providing a protective layer against corrosion. Furthermore, because the multilayer graphene film consists of 3-6 layers with a thickness of only 1-3 nm, its light weight is negligible, resulting in a negligible increase in cell mass. Higher battery capacity per unit mass can be achieved without an additional protective film. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0032] Figure 1 This is a flowchart of the electrochemical anode preparation method according to an embodiment of the present invention;

[0033] Figure 2(a) is a physical image of the copper-based multilayer graphene according to an embodiment of the present invention, and Figure 2(b) is the Raman spectrum corresponding to the cross-marked area in Figure 2(a).

[0034] Figure 3This is a cross-sectional view of copper-based multilayer graphene according to an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the etching and transfer of small-sized multilayer graphene according to an embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the electrochemical anode preparation equipment according to an embodiment of the present invention;

[0037] Figure label:

[0038] 101-Etching tank, 102-Cleaning tank, 201-First unwinding roller, 202-Transfer roller, 203-Laying roller, 204-Second unwinding roller, 205-Rewinding roller, 3-Drying equipment, 401-Multilayer graphene / initial substrate composite structure, 402-Multilayer graphene film, 403-Target substrate, 404-Electrochemical anode wrapped with graphene film. Detailed Implementation

[0039] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0040] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0041] Example

[0042] This embodiment provides a method for large-scale preparation of electrochemical anodes based on graphene film encapsulation, such as... Figure 1 As shown, it includes the following steps:

[0043] Step 1: Place the multilayer graphene / initial substrate composite structure in an etching solution to etch the initial substrate, thereby obtaining a multilayer graphene film.

[0044] In some embodiments, when the initial substrate is copper, the etching solution is selected as ferric chloride (FeCl3) solution or ammonium persulfate (NH4)2S2O8 solution; when the initial substrate is nickel or a copper-nickel alloy, the etching solution is selected as ammonium sulfate (NH4)2S2O8 solution. The etching time is not limited and is set according to the thickness of the initial substrate until the initial substrate is completely etched away.

[0045] Specifically, taking copper as the initial substrate as an example, the physical specimens of the multilayer graphene / initial substrate composite structure are shown in Figures 2(a) and 2(b), and their cross-sections are shown in Figure 3. The etching solution used is FeCl3 solution. To facilitate understanding by those skilled in the art, the etching process of a small-sized multilayer graphene / initial substrate composite structure is demonstrated. The etching process is as follows: Figure 4 As shown, from Figure 4 It can be seen that the obtained multilayer graphene film can self-suspend on the liquid surface.

[0046] In some embodiments, the resulting multilayer graphene film has 3-6 layers.

[0047] Step 2: Transfer the multilayer graphene film to the cleaning solution by rolling it up for rinsing.

[0048] In some embodiments, the cleaning solution may be deionized water, ethanol or chloroform, to clean the residual etching solution on the multilayer graphene film, and the rinsing time is preferably 10 minutes.

[0049] Step 3: The target substrate is rolled up and bonded to the upper surface of the rinsed multilayer graphene film to obtain an electrochemical anode wrapped in graphene film.

[0050] In some embodiments, the target substrate may be zinc or aluminum. Using these two metals to prepare the anode can eliminate the need for a conductive agent, increase the density of the active material, and thus increase the overall energy density of the battery.

[0051] In a specific implementation, the raw materials used in the above preparation method include multilayer graphene / initial substrate structures, and the preparation method is illustrated by CVD (chemical vapor deposition):

[0052] (1) Pump the CVD equipment to <3Pa, check for leaks in the equipment, and after the pressure rise rate is <0.2Pa / min, directly charge the CVD equipment with growth gas.

[0053] (2) Introduce a gas with a C / H ratio of 1000:10 to 1000:100 into the equipment. The carbon-containing gas includes CH4 and C2H2, etc. The H2 is an Ar / H2 gas with a H2 ratio of 10%. Ar is used as a transport gas to change the equipment from a vacuum state of <3Pa to an atmospheric pressure state.

[0054] (3) After the equipment is charged to normal pressure, the CVD equipment is heated from 25°C to 1000°C within 1.5 hours.

[0055] (4) After the equipment reaches 1000℃, it begins to rotate the initial substrate material. The transmission speed of the initial substrate material can be set to 1mm / min to 1000mm / min until roll-to-roll growth yields a multilayer graphene / initial substrate structure of a preset length. In a specific manner, the initial substrate material can be copper foil, nickel foil, or copper-nickel alloy with different component ratios, and the preset length is not less than 1000 meters.

[0056] The equipment used, such as Figure 5 As shown, it includes:

[0057] The first unwinding roller 201 has a multi-layer graphene / initial substrate composite structure 401 wound on it, and its position is not limited.

[0058] An etching tank 101 is located below the first unwinding roller and contains etching solution. The gap between the upper surface of the etching solution and the bottom of the first unwinding roller is not less than the thickness of the multilayer graphene / initial substrate composite structure. After the initial substrate is etched away in the etching tank by the etching solution, a multilayer graphene film 402 is obtained. The shape and size of the etching tank are not limited, but are determined according to the length and width of the multilayer graphene film to be processed.

[0059] Cleaning tank 102 is filled with cleaning solution to rinse away residual etching solution on the multilayer graphene film; the shape and size of the cleaning tank are not limited, but are determined according to the length and width of the multilayer graphene film to be processed.

[0060] The second unwinding roller 204 has the target substrate 403 wound on it, and its position is not limited.

[0061] A bonding roller 203 is positioned above the tail end of the cleaning tank. The gap between the upper surface of the cleaning liquid and the bottom of the bonding roller is no greater than the sum of the thicknesses of the multilayer graphene film and the target substrate. When the bonding roller rotates, it rolls the target substrate onto the upper surface of the multilayer graphene film, and uses friction to bond the target substrate and the multilayer graphene film together, resulting in an electrochemical anode 404 wrapped in graphene film.

[0062] The take-up roller 205 rotates to take up the electrochemical anode wrapped with graphene film obtained at the bonding roller, and its position is not limited.

[0063] For the above equipment, the rotational speeds of the unwinding roller, the conveying roller, and the rewinding roller can be set to allow the multilayer graphene / initial substrate composite structure to be etched away in the etching tank and then rinsed in the cleaning tank.

[0064] In some embodiments, to make the transfer of the multilayer graphene film from the etching tank to the cleaning tank smoother, a conveying roller 202 can be added. The conveying roller is located between the etching tank and the cleaning tank and drives the multilayer graphene film to move towards the cleaning tank by rotating.

[0065] In some embodiments, a drying device 3 may be added, which is located between the bonding roller and the winding roller to dry the electrochemical anode wrapped with graphene film before winding, and to blow away any residual cleaning liquid. The choice of drying device is not limited, and it can be implemented by any feasible method in the prior art, such as a dryer.

[0066] Through the technical solution of this embodiment, the multilayer graphene film is directly bonded to zinc foil after being transported by means of self-suspension. This processing method is simple and easy to implement, and can easily achieve large-scale application. In addition, it has a wider selection of substrates, and any object with a fixed shape can be used as the target substrate for bonding.

[0067] In terms of performance, a self-suspended method is used to attach multilayer graphene films onto zinc foil. To address the poor reversibility of the zinc anode in zinc-ion aqueous batteries, a medium is used to cover the zinc foil electrode, thereby inducing zinc ion deposition. The multilayer graphene film makes the zinc foil surface smoother, reducing the tip effect and preventing uneven growth of zinc ions and dendrite formation during deposition. Compared with existing LB film deposition, transferring multilayer graphene films prepared by CVD onto zinc foil using a self-suspended method results in greater stability because the graphene film encapsulating the anode is a continuous film rather than fragmented graphene, which is easily detached and separated.

[0068] Compared with existing technologies, the technical solution of this embodiment does not require an additional protective film during the preparation of the electrochemical anode. A multilayer graphene film is directly bonded to the zinc foil using a self-suspending method, thus providing a protective layer against corrosion. For the battery, since the film covering on the anode does not contribute to capacity, and because the multilayer graphene film consists of 3-6 layers with a thickness of only 1-3 nm, its light weight is negligible in increasing the cell's mass. Therefore, a higher battery capacity per unit mass can be provided without using an additional protective film.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for large-scale preparation of electrochemical anodes based on graphene film encapsulation, characterized in that, Includes the following steps: The multilayer graphene / initial substrate composite structure is placed in an etching solution to etch the initial substrate, thereby obtaining a multilayer graphene film. The multilayer graphene film is self-suspended on the surface of the etching solution. The multilayer graphene film suspended on the surface of the etching solution is transferred to the cleaning solution for rinsing by rolling. The target substrate is rolled up and bonded to the upper surface of a rinsed multilayer graphene film to obtain an electrochemical anode wrapped in graphene film. The target substrate includes zinc or aluminum.

2. The method for large-scale preparation of electrochemical anodes based on graphene film encapsulation according to claim 1, characterized in that, The multilayer graphene / initial substrate composite structure was prepared by chemical vapor deposition.

3. The method for large-scale preparation of electrochemical anodes based on graphene film encapsulation according to claim 1, characterized in that, The initial substrate includes copper, nickel, or a copper-nickel alloy; when the initial substrate is copper, the etching solution includes FeCl3 solution or (NH4)2S2O8 solution; when the initial substrate is nickel or a copper-nickel alloy, the etching solution includes (NH4)2S2O8 solution.

4. The method for large-scale preparation of electrochemical anodes based on graphene film encapsulation according to claim 1, characterized in that, The multilayer graphene film has 3-6 layers.

5. The method for large-scale preparation of electrochemical anodes based on graphene film encapsulation according to claim 1, characterized in that, The cleaning solution includes deionized water, ethanol, or chloroform.

6. An apparatus for preparing an electrochemical anode based on graphene film coating, used to implement the preparation method according to any one of claims 1-5, characterized in that, include: The first unwinding roll has a multilayer graphene / initial substrate composite structure wound on it; An etching tank is located below the first unwinding roller; the etching tank is filled with etching liquid, and the gap between the upper surface of the etching liquid and the bottom of the first unwinding roller is not less than the thickness of the multilayer graphene / initial substrate composite structure. A cleaning tank containing a cleaning solution; The second unwinding roll has the target substrate wound on it. A bonding roller is positioned above the tail end of the cleaning tank, and the gap between the upper surface of the cleaning liquid and the bottom of the bonding roller is no greater than the sum of the thicknesses of the multilayer graphene film and the target substrate. and A take-up roller, which rotates to take up the electrochemical anode wrapped with a graphene film obtained at the bonding roller.

7. The electrochemical anode preparation device based on graphene film encapsulation according to claim 6, characterized in that, It also includes a conveyor roller, which is located between the etching tank and the cleaning tank and drives the multilayer graphene film to move towards the cleaning tank by rotating.

8. The electrochemical anode preparation device based on graphene film encapsulation according to claim 6, characterized in that, It also includes a drying device, which is located between the bonding roller and the take-up roller.

9. An electrochemical anode based on graphene film coating, characterized in that, It is prepared by the method described in any one of claims 1-5.

Images