A method for preparing a roll-to-roll graphene heat sink

Abstract

The present invention discloses a roll-to-roll method for preparing a graphene heat sink. The roll-to-roll method comprises attaching GO (graphene oxide) to one surface of a multilayer graphene sheet to obtain a GO-covered multilayer graphene sheet. After attachment, two sheets of the GO-covered multilayer graphene sheet are laminated with the GO surfaces facing each other and then rolled to obtain a sandwich structure. The outer surfaces of the sandwich structure are connected to positive and negative electrodes for discharge, respectively, and the GO sheets facing each other are subjected to high-temperature reduction to RGO. The present invention discloses a method for instantaneously reducing GO using capacitor discharge to achieve roll-to-roll preparation of heat sinks. Compared with the high-temperature graphitization method commonly used in the prior art, this method can greatly reduce energy consumption. According to an estimated total energy of 1 kW per single capacitor discharge, this method reduces energy consumption per unit area by at least 50% compared to temperatures reaching 2800-3000°C.

Description

Technical Field

[0001] The invention discloses a method for preparing a roll-to-roll graphene heat sink, and relates to the technical field of graphene heat sink preparation. Background Art

[0002] The main material of the graphite heat sink is artificial graphite sheet. Reference patent (CN 103080005A) discloses artificial graphite film and its manufacturing method. This method produces the artificial graphite film by high-temperature carbonization and graphitization of a polyimide film. The method first involves heating a polyimide (PI) film in a thermal resistance graphitization furnace at a temperature of 1100-1300°C to carbonize the PI film, forming a carbonized PI sheet. The carbonized PI sheet is then heated at a temperature of 2800-3000°C to graphitize the sheet, forming a PI graphite heat sink. The PI graphite heat sink is then cooled to room temperature and then rolled using a rolling device to form a finished graphite heat sink with a thickness of 15-30 μm. The thickness of the thermal conductive film material can be designed, the heat dissipation effect is good, and the density is low, which can well meet the requirements of light and thin electronic products. However, the graphitization process requires a lot of time (heating time is at least 6 to 10 minutes per hour, and cooling time is at least 10 minutes per hour) and energy (the energy consumption of the experimental furnace is at least 50 to 70 kW / h), which leads to high energy consumption and high cost.

[0003] SUMMARY OF THE INVENTION

[0004] The present invention aims to provide a method for preparing a roll-to-roll graphene heat sink, thereby reducing the energy consumption and cost of preparing the graphene heat sink and improving the preparation efficiency.

[0005] In order to achieve the above technical objectives and effects, the invention is implemented through the following technical solutions:

[0006] A roll-to-roll graphene heat sink preparation method, comprising: attaching GO (graphene oxide) to one surface of a multilayer graphene to obtain GO-covered multilayer graphene; after the attachment is completed, two sheets of the GO-covered multilayer graphene are attached with the GO surfaces facing each other and then rolled to obtain a sandwich structure;

[0007] The outer surfaces of both sides of the sandwich structure are respectively connected to the positive and negative electrodes for discharge, and the GO facing each other generates high temperature and is reduced to RGO.

[0008] Furthermore, the multilayer graphene is a graphene layer covering the surface of a conductive metal, and after rolling to form the sandwich structure, the external power supply of the conductive metal is a capacitor.

[0009] Furthermore, the method specifically includes the following steps:

[0010] S1, the conductive metal is Cu, and multilayer graphene nGr / Cu is prepared based on a roll-to-roll CVD device, and GO is attached to obtain a GO / nGr / Cu structure;

[0011] S2. Roll-press two prepared GO / nGr / Cu structures with the GO surfaces facing each other to obtain a Cu / nGr / GO / GO / nGr / Cu sandwich structure with two layers of GO at the center.

[0012] S3. The positive and negative electrodes of the capacitor are connected to the two Cu layers respectively. After the capacitor is discharged, the electricity will be instantly transferred to GO, generating high temperature to reduce GO to RGO, and obtaining a Cu / nGr / RGO / RGO / nGr / Cu structure.

[0013] Furthermore, the nGr / Cu is rolled to roll through a GO suspension to adsorb GO, forming a rolled Cu / nGr / GO;

[0014] The wound Cu / nGr / GO sandwich is laminated to form Cu / nGr / GO / GO / nGr / Cu.

[0015] Furthermore, the method further includes S4: removing Cu by etching to obtain nGr / RGO / RGO / nGr.

[0016] Furthermore, the sandwich structure is used to prepare graphene heat sinks.

[0017] Another object of the present invention is to disclose a graphene heat sink obtained by stretching and then shearing the multi-layer sandwich structure.

[0018] Beneficial effects:

[0019] 1. The sandwich structure of multi-layer graphene film and graphene powder is more stable and solves the problem of easy powder loss at the edge.

[0020] 2. When the copper foil substrate is used as a sample pressing buffer layer, the integrity of the graphene film can be ensured during the sample pressing process; secondly, after the graphene growth, both sides of the copper foil will be covered with graphene film, which can improve the corrosion resistance of the copper foil.

[0021] 3. The present invention discloses a method for instantaneously reducing GO by capacitor discharge and realizing roll-to-roll preparation of heat sinks. Compared with the high-temperature graphitization in a heating furnace commonly used in the prior art, it can greatly reduce energy consumption. According to the total energy of a single capacitor discharge estimated to be 1KW, the energy consumption per unit area is at least 50% lower than that when the temperature is raised to 2800-3000℃.

[0022] 4. GO is negatively charged, so a certain positive potential can be set during the nGr / Cu bonding process to achieve intelligent adjustment of GO thickness.

[0023] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the preparation process according to an embodiment of the present invention;

[0025] Figure 2 This is a picture of the change of nGr / Cu in FeCl3 etching solution over time in an embodiment of the present invention;

[0026] Figure 3 is an optical photograph of a multilayer graphene pattern transferred to SiO2 / Si in an embodiment of the present invention;

[0027] Figure 4 This is a Raman spectrum obtained by measuring the cross region of the multilayer graphene image in an embodiment of the present invention; DETAILED DESCRIPTION

[0028] Prior art patent (CN 103157809B) discloses a method for preparing a graphene / metal nanoparticle composite material with a sandwich structure. In this method, graphene oxide (GO) is reduced to graphene (G), and metal ions (Mn+) in the main salt are reduced to metal (M), with both reactions occurring simultaneously. The reduced metal nanoparticles are deposited on the graphene surface. After centrifugation and vacuum drying, a graphene / metal nanoparticle composite material with a sandwich structure is obtained. The present invention, however, reduces GO to RGO through instantaneous capacitor discharge and heating, which is fundamentally different.

[0029] In order to more clearly illustrate the technical solution of the present invention, the present invention will be described in detail below with reference to embodiments.

[0030] Example 1

[0031] This embodiment relates to a method for preparing self-suspended multilayer graphene, specifically using a roll-to-roll chemical vapor deposition (CVD) device to prepare multilayer graphene, which can exist independently without the need to spin-coat a polymer support layer on the graphene surface. The self-suspended experimental results are shown in FIG. Figure 1 As shown, the optical and Raman images of multilayer graphene transferred to SiO2 / Si are as follows Figure 2 shown.

[0032] In the examples, multilayer graphene (nGr / Cu) was used to attach commercially available graphene oxide (GO). A positive potential was applied to the Cu end of the nGr / Cu. Because GO graphene contains -OH and -COOH groups, it generally exhibits a negative potential. Therefore, applying different positive potentials to the Cu end of the nGr / Cu can control the thickness of the adsorbed GO.

[0033] In this example, a GO / nGr / Cu and GO / nGr / Cu sandwich structure of desired thickness was prepared, with the structure being Cu / nGr / GO / GO / nGr / Cu. The Cu / nGr / GO / GO / nGr / Cu was then roll-formed under pressure, and the connected capacitor was momentarily discharged. In a preferred embodiment, the instantaneous discharge of the capacitor generated heat reaching 3000°C.

[0034] Specifically, two copper wires are attached to the ends of the Cu / nGr / GO / GO / nGr / Cu structure. Because Cu and nGr are both good conductors, while GO is a poor conductor, electricity is instantly transferred to GO. As in the preferred embodiment described above, a high temperature of 3000°C is generated, reducing GO to reduced graphene oxide (RGO).

[0035] The nGr / Cu in this embodiment is prepared by a roll-to-roll CVD device, so nGr / Cu can be rolled up in a roll-to-roll manner. Similarly, nGr / Cu can absorb GO in a roll-to-roll manner to form a rolled Cu / nGr / GO. Then, the rolled Cu / nGr / GO can be laminated to form

[0036] Cu / nGr / GO / GO / nGr / Cu. The capacitor discharge circuit is connected to the

[0037] Cu / nGr / GO / GO / nGr / Cu are in contact, which will not affect the roll-to-roll process, and finally Cu / nGr / RGO / RGO / nGr / Cu is obtained.

[0038] Example 2

[0039] This embodiment relates to setting a positive potential during the Gr / Cu attachment process to adjust the GO thickness, and the specific implementation of preparing a heat sink using the method of the present invention.

[0040] In this example, nGr / Cu is used to attach graphene oxide (GO). A positive potential is applied to the Cu end of the nGr / Cu layer. Because GO graphene contains -OH and -COOH groups, it generally exhibits a negative potential. In this example, the positive potential at the Cu end is set between 0.1V and 100V, which can be used to adjust the thickness of the adsorbed GO. Depending on specific needs, the thickness of the GO can be controlled by adjusting the positive potential to suit different application scenarios.

[0041] In one specific embodiment, the Cu / nGr / RGO / RGO / nGr / Cu obtained in Example 1 is cut and used directly or after Cu is etched to prepare a heat sink. The heat sink in this embodiment can be widely used in electronic devices, such as computers and mobile phones, to dissipate heat generated during operation.

[0042] The above is only part of the embodiment of the application and does not limit the application in any form. Any simple modification, equivalent change and modification made to the above embodiment still falls within the scope of protection of the technical solution of the application.

Claims

1. A method for preparing a roll-to-roll graphene heat sink, characterized in that: GO (graphene oxide) is attached to one surface of the multilayer graphene to obtain GO-covered multilayer graphene. After the attachment is completed, two pieces of the GO-covered multilayer graphene are attached with the GO surfaces facing each other and then rolled to obtain a sandwich structure; The outer surfaces of both sides of the sandwich structure are connected to the positive and negative electrodes for discharge, and the GO facing each other generates high temperature and is reduced to RGO; The multilayer graphene is a graphene layer covering the surface of the conductive metal, and after rolling to form the sandwich structure, the conductive metal is connected to an external power supply as a capacitor; The specific steps include: S1, the conductive metal is Cu, and multilayer graphene nGr / Cu is prepared based on a roll-to-roll CVD device, and GO is attached to obtain a GO / nGr / Cu structure; S2. Roll-press two prepared GO / nGr / Cu structures with the GO surfaces facing each other to obtain a Cu / nGr / GO / GO / nGr / Cu sandwich structure with two layers of GO at the center. S3. The positive and negative electrodes of the capacitor are connected to the two Cu layers respectively. After the capacitor is discharged, the electricity will be instantly transferred to GO, generating high temperature to reduce GO to RGO, and obtain the Cu / nGr / RGO / RGO / nGr / Cu structure.

2. The method for preparing a roll-to-roll graphene heat sink according to claim 1, wherein: The nGr / Cu is rolled to roll through the GO suspension to adsorb GO, forming a rolled Cu / nGr / GO; The wound Cu / nGr / GO sandwich is laminated to form Cu / nGr / GO / GO / nGr / Cu.

3. The method for preparing a roll-to-roll graphene heat sink according to claim 1, wherein: The process also includes S4: removing Cu by etching to obtain nGr / RGO / RGO / nGr.

4. The method for preparing a roll-to-roll graphene heat sink according to claim 1, wherein: During the nGr / Cu GO attachment process, the positive potential was set to 0.1V~100 V to adjust the thickness of GO.

5. The method for preparing a roll-to-roll graphene heat sink according to claim 1, wherein: The sandwich structure is used to prepare graphene heat sinks.

6. A graphene heat sink prepared according to the method of claim 1 or 4, characterized in that: The multi-layer sandwich structure is obtained by stretching and then shearing.

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