A preparation method of a graphene-based thermal interface material based on copper nanowire loading
By growing copper nanowires in situ between graphene layers to form a thermally conductive network, the problem of low longitudinal thermal conductivity in graphene-based thermal interface materials is solved, achieving high thermal conductivity and good heat dissipation, which is suitable for thermal management of electronic products.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIAMEN UNIV
- Filing Date
- 2023-05-17
- Publication Date
- 2026-05-19
AI Technical Summary
Existing graphene-based thermal interface materials have low longitudinal thermal conductivity and high anisotropy, which cannot effectively diffuse excess heat vertically from the heat source to the heat sink, thus failing to meet the heat dissipation requirements of increasingly miniaturized and highly integrated electronic products.
A one-pot reduction method was used to grow copper nanowires in situ between graphene layers to form a uniform thermally conductive network, thus preparing a copper nanowire/graphene composite material. The copper nanowires were loaded between the graphene layers to improve the thermal conductivity.
The longitudinal thermal conductivity of graphene-based composite materials is improved, anisotropy is reduced, and heat dissipation capacity is enhanced, making them suitable for thermal interface materials to address excess heat issues in electronic devices.
Smart Images
Figure CN116589987B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of nanomaterials technology, and in particular to a method for preparing a graphene-based thermal interface material supported by copper nanowires. Background Technology
[0002] In recent years, the rapid miniaturization of electronic and photonic devices has attracted widespread attention. Severe heat dissipation problems have become a bottleneck affecting their stability and reliability, making effective thermal management of various electronic devices extremely urgent. The main goal of thermal management is to transfer excess heat from electronic devices to the surrounding environment. Generally, the heat removal process mainly includes four heat transfer stages: (1) heat transfer inside the device; (2) heat transfer from the device to the heat sink; (3) heat transfer through the heat sink; and (4) heat transfer from the heat sink to the surrounding environment. The heat transfer between the device and the heat sink is usually considered the ultimate heat transfer stage.
[0003] As is well known, when two rigid solid materials (device and heatsink) only contact at the top of the protrusions on their contact surfaces, high contact thermal resistance results due to the microscopic roughness of the heatsink and the integrated circuit or electronic device. Thermal interface materials are widely used in electronic components to reduce the low thermal conductivity (0.026 W / m²) between the heat source and the heatsink. -1 K -1 Thermal interface materials mitigate the thermal resistance caused by the interfacial air and remove excess heat from devices to enhance thermal conduction at the interface between the heat source and the heat sink. However, improving thermal conductivity and reducing contact thermal resistance remains a challenge for thermal interface materials in meeting the increasingly demanding requirements of high-frequency and highly integrated electronics. These requirements necessitate a rethinking of the physical basis and practical application requirements of thermal interface materials to understand how to improve their heat dissipation capabilities.
[0004] In recent years, graphene-based materials have gained widespread favor in the development of thermal interface materials due to their lightweight, strong mechanical properties, and high thermal conductivity. Layered composite materials obtained by combining graphene with metal materials not only inherit the high thermal conductivity of graphene but also possess the mechanical properties of metals.
[0005] Chinese patents CN102176338A, CN105023629A, CN109346208A, and CN110695371A disclose the preparation of copper nanowire / graphene composite materials by adding polymers as binders. The composite materials prepared by these methods exhibit extremely low thermal conductivity, primarily because the inherently low thermal conductivity of the polymers reduces the overall thermal performance of the material. The main problem with these technologies is that these layered composite materials cannot uniformly form a thermally conductive network, have very low longitudinal thermal conductivity, and exhibit high anisotropy, thus failing to effectively diffuse excess heat vertically from the heat source to the heat sink. Therefore, it is necessary to prepare a composite material with high thermal conductivity and high heat dissipation capacity to serve as a thermal interface material to address the heat dissipation problems of increasingly miniaturized and highly integrated electronic products. Summary of the Invention
[0006] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and to provide a method for preparing graphene-based thermal interface materials with high thermal conductivity and high heat dissipation capacity by using copper nanowires as a support, addressing the problems of low longitudinal thermal conductivity and high anisotropy of graphene-based thermal interface materials.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] A method for preparing a graphene-based thermal interface material supported by copper nanowires includes the following steps:
[0009] 1) Add graphene to ethanol and sonicate to obtain a graphene dispersion;
[0010] 2) Add the graphene dispersion and copper salt solution to the sodium hydroxide solution and stir continuously;
[0011] 3) Add the ethylenediamine and hydrazine hydrate solution to the mixed solution in step 2) and heat in a water bath;
[0012] 4) After heating, cool, filter, wash, dry, and compress to obtain the product.
[0013] In step 2), the concentration of the sodium hydroxide solution is 10–15 mol / L.
[0014] In step 2), the copper salt is either copper nitrate or copper chloride.
[0015] In step 3), the mass concentration of the hydrazine hydrate solution is 30%–40%.
[0016] In step 3), the volume ratio of hydrazine hydrate solution to ethylenediamine is 1:(6-24).
[0017] In step 3), the heating temperature is 60-80℃ and the heating time is 45-90 minutes.
[0018] In step 4), the washing is performed at least 4 times with a hydrazine hydrate solution, the mass concentration of which is 3% to 5%.
[0019] In step 4), the tablet is pressed using plasma sintering.
[0020] A graphene-based thermal interface material based on copper nanowires was prepared using the above method. It consists of copper nanowires and graphene sheets, with the copper nanowires loaded between the graphene layers and forming a uniform thermally conductive network on the graphene surface.
[0021] By mass ratio, graphene accounts for 60%–80%, and copper accounts for 20%–40%.
[0022] Compared with the prior art, the beneficial effects achieved by the technical solution of this invention are:
[0023] This invention employs a one-pot reduction method, first dispersing a copper source between graphene layers, then in-situ reducing and growing copper nanowires, ultimately yielding a uniformly dispersed and tightly bonded copper nanowire / graphene composite material. Experiments demonstrate that copper nanowires possess excellent thermal conductivity, effectively establishing a thermally conductive network on the graphene sheets, increasing surface heat conduction pathways, and improving heat flux. Simultaneously, the incorporation of copper nanowires into the graphene interlayer promotes interlayer heat transfer, increasing the longitudinal thermal conductivity of the graphene-based composite material and reducing anisotropy. The novel copper nanowire-supported graphene-based thermal composite material prepared by this invention exhibits high thermal conductivity and excellent heat dissipation, and can serve as a thermal interface material to significantly address the problem of excess heat generated in electronic devices. Attached Figure Description
[0024] Figure 1 For Gr 60 -CuNWs 40 Scanning electron microscope image;
[0025] Figure 2 For graphene, Gr 80 -CuNWs 20 Gr 60 -CuNWs 40 The longitudinal thermal conductivity diagram;
[0026] Figure 3 For graphene, Gr 80 -CuNWs 20 Gr 60 -CuNWs 40 The graph shows the longitudinal thermal conductivity as a function of temperature.
[0027] Figure 4For 1W LED, LED & graphene, LED & commercial heat sink aluminum sheet, LED & Gr 60 -CuNWs 40 Thermal images at a stable voltage of 3V. Detailed Implementation
[0028] To make the technical problems, technical solutions and beneficial effects of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0029] Example 1
[0030] Weigh 40g of sodium hydroxide and dissolve it in 100mL of deionized water to obtain a high-concentration sodium hydroxide solution. Weigh 0.048g of graphene and dissolve it in 20mL of ethanol solution, then sonicate it for 15min. Add the graphene dispersion to the sodium hydroxide solution, and add 5mL of 0.1mol / L copper nitrate solution. Stir the mixture continuously for 30min. Add 1.5mL of ethylenediamine and 0.125mL of hydrazine hydrate solution (35% by mass) to the stirred solution, and place the mixture in a water bath and heat it at 60℃ for 1h. After the solution cools to room temperature, vacuum filter the mixture and wash it at least 4 times with 3% hydrazine hydrate solution. Dry the resulting precipitate in a vacuum oven at 60℃ overnight. Press the dried product into tablets by plasma sintering to obtain Gr. 60 -CuNWs 40 Composite materials.
[0031] Example 2
[0032] Weigh 50g of sodium hydroxide and dissolve it in 100mL of deionized water to obtain a high-concentration sodium hydroxide solution. Weigh 0.125g of graphene and dissolve it in 20mL of ethanol solution, then sonicate it for 20min. Add the graphene dispersion to the sodium hydroxide solution, and add 10mL of 0.1mol / L copper nitrate solution. Stir the mixture continuously for 30min. Add 1.5mL of ethylenediamine and 0.25mL of hydrazine hydrate solution (35% by mass) to the stirred solution, and place the mixture in a water bath and heat it at 60℃ for 1h. After the solution cools to room temperature, vacuum filter the mixture and wash it at least 4 times with 4% hydrazine hydrate solution. Dry the resulting precipitate in a vacuum oven at 80℃ overnight. Press the dried product into tablets by plasma sintering to obtain Gr. 70 -CuNWs 30 Composite materials.
[0033] Example 3
[0034] 60g of sodium hydroxide was weighed and dissolved in 100mL of deionized water to obtain a high-concentration sodium hydroxide solution. 0.25g of graphene was weighed and dissolved in 20mL of ethanol solution, and then sonicated for 30min. The graphene dispersion was added to the sodium hydroxide solution, along with 5mL of 0.2mol / L copper nitrate solution, and the mixture was stirred continuously for 1h. 3mL of ethylenediamine and 0.25mL of hydrazine hydrate solution (35% by mass) were added to the stirred solution, and the mixture was placed in a water bath and heated at 80℃ for 1.5h. After the solution cooled to room temperature, the mixture was vacuum filtered and washed at least four times with 5% hydrazine hydrate solution. The resulting precipitate was dried overnight in a vacuum oven at 80℃. The dried product was then subjected to plasma sintering and tableting to obtain Gr. 80 -CuNWs 20 Composite materials.
[0035] The thermal conductivity of the composite material obtained in the examples was tested using the following specific methods:
[0036] Laser flare analyzers are commonly used instruments in thermal analysis. They heat a sample surface by striking it with laser pulses, and after recording the temperature change, the changes in parameters such as emission power, temperature, and time are integrated and calculated to obtain the thermal diffusivity of the material. They can measure the thermal diffusivity in both the transverse and longitudinal directions of solid and liquid materials. The relationship between the thermal diffusivity (α) and thermal conductivity (K) is as follows:
[0037]
[0038] Figure 1 For Gr 60 -CuNWs 40 Scanning electron microscope image. From Figure 1 As can be seen from a, copper nanowires are uniformly distributed on the graphene sheets, forming an ordered thermally conductive network; from Figure 1 As can be seen from b, copper nanowires have an ultra-high aspect ratio, thus exhibiting excellent thermal conductivity.
[0039] Figure 2 For graphene, Gr 80 -CuNWs 20 Gr 60 -CuNWs 40 The graph shows a comparison of the longitudinal thermal conductivity of graphene and copper nanowires. As can be seen from the graph, the loading of copper nanowires significantly improves the longitudinal thermal conductivity of the composite material compared to pure graphene. Furthermore, the longitudinal thermal conductivity increases with the increase of copper nanowire doping content; when the copper content reaches 40 wt%, the longitudinal thermal conductivity is more than twice that of pure graphene.
[0040] Figure 3 For graphene, Gr 80 -CuNWs 20 Gr 60 -CuNWs 40 The graph shows the change in longitudinal thermal conductivity with temperature. As can be seen from the graph, the longitudinal thermal conductivity of the composite material decreases with increasing temperature. This is because the expansion of residual air between the layers due to increased temperature increases the interlayer distance of the graphene sheets, narrowing or even eliminating the efficient heat flow channels between the layers.
[0041] Figure 4 From top to bottom, the components are: 1W LED, LED & Graphene, LED & Commercial Heatsink Aluminum Sheet, and LED & Graphene. 60 -CuNWs 40 Thermal images at a stable 3V voltage are shown. The images demonstrate that, compared to pure graphene and commercial aluminum heat sinks, the copper nanowire / graphene composite material accelerates heat dissipation and cools down rapidly under the same heat source conditions. This is because the composite material possesses a higher thermal conductivity or weaker anisotropy in heat transfer. At the same temperature gradient, materials with higher thermal conductivity allow more heat to pass through per unit time, thus being more beneficial for heat dissipation.
[0042] This invention uses graphene, which has high thermal conductivity, as a substrate and grows copper nanowires in situ between its layers. This promotes thermal transfer between graphene layers, increases the longitudinal thermal conductivity of the graphene-based composite material, reduces its anisotropy, and thus provides higher heat dissipation capacity. This invention can be used as a thermal interface material to improve the performance stability and lifespan of electronic products, and helps solve the heat dissipation problems of increasingly miniaturized and highly integrated electronic products.
Claims
1. A method for preparing a graphene-based thermal interface material supported by copper nanowires, characterized in that... Includes the following steps: 1) Graphene was added to ethanol and ultrasonically treated to obtain a graphene dispersion; 2) Add the graphene dispersion and copper salt solution to the sodium hydroxide solution and stir continuously; 3) Add the ethylenediamine and hydrazine hydrate solution to the mixed solution in step 2) and heat in a water bath; 4) After heating, the material is cooled, vacuum filtered, washed, dried, and pressed into tablets to obtain a graphene-based thermal interface material supported by copper nanowires. The graphene-based thermal interface material supported by copper nanowires is composed of copper nanowires and graphene sheets. The copper nanowires are loaded between the graphene layers and form a uniform thermally conductive network on the graphene surface. By mass ratio, the graphene accounts for 60% to 80% and the copper accounts for 20% to 40%.
2. The method for preparing a graphene-based thermal interface material supported by copper nanowires as described in claim 1, characterized in that: In step 2), the concentration of the sodium hydroxide solution is 10–15 mol / L.
3. The method for preparing a graphene-based thermal interface material supported by copper nanowires as described in claim 1, characterized in that: In step 2), the copper salt is either copper nitrate or copper chloride.
4. The method for preparing a graphene-based thermal interface material supported by copper nanowires as described in claim 1, characterized in that: In step 3), the mass concentration of the hydrazine hydrate solution is 30% to 40%.
5. The method for preparing a graphene-based thermal interface material supported on copper nanowires as described in claim 4, characterized in that: In step 3), the volume ratio of hydrazine hydrate solution to ethylenediamine is 1:(6-24).
6. The method for preparing a graphene-based thermal interface material supported by copper nanowires as described in claim 1, characterized in that: In step 3), the heating temperature is 60-80℃ and the heating time is 45-90 minutes.
7. The method for preparing a graphene-based thermal interface material supported by copper nanowires as described in claim 1, characterized in that: In step 4), the washing is performed at least 4 times with a hydrazine hydrate solution, the mass concentration of which is 3% to 5%.
8. The method for preparing a graphene-based thermal interface material supported by copper nanowires as described in claim 1, characterized in that: In step 4), the tablet is pressed using plasma sintering.