Preparation method and application of Ag@MXene composite high thermal conductivity slurry

Abstract

The present invention discloses a preparation method and application of a Ag@MXene composite high-thermal conductivity slurry, belonging to the technical field of thermal interface materials. The preparation method of the Ag@MXene composite high-thermal conductivity slurry comprises the following steps: etching a Ti3AlC2 precursor with hydrofluoric acid (HF) to obtain layered MXene; ultrasonically dispersing the MXene in deionized water, simultaneously dissolving AgNO3 in the deionized water, slowly adding the AgNO3 solution to the MXene dispersion, stirring, and then drying to obtain an Ag@MXene composite material; and thoroughly mixing the Ag@MXene composite material with flaky silver powder and epoxy resin to obtain an Ag@MXene composite slurry. The Ag@MXene composite slurry prepared by the present invention has a maximum thermal conductivity of 40.80 W / (m·K).

Description

Technical Field

[0001] The present invention relates to a preparation method and application of an Ag@MXene composite high thermal conductivity slurry, belonging to the technical field of thermal interface materials. Background Art

[0002] As electronic devices become increasingly miniaturized, high-power, and highly integrated, heat accumulation within circuits significantly impacts their performance and lifespan. To address this issue, thermal management has become a crucial issue for improving device performance and lifespan in areas such as high-power supercomputers, communication base stations, and electric vehicles. Thermal interface materials (TIMs) are a crucial component of effective thermal management. They effectively transfer heat from the circuit to the surrounding environment by filling the inevitable air gaps between the heat generating device and the heat sink.

[0003] Compared with other thermal interface materials, thermal conductive paste has excellent adhesion, which can directly bond the heating device and the radiator tightly together. Thermal conductive paste is usually a paste made by blending thermal conductive fillers and polymers, and then the thermal conductive paste is brushed on the surface of the heating device or radiator by coating, dispensing, screen printing, etc., and finally the two surfaces are bonded by high-temperature curing to isolate the air gap. However, due to a large number of inherent defects between the chain ends, such as phonon scattering, entanglement and impurities, the thermal conductivity coefficient of most bulk polymers is low. In order to improve the thermal conductivity of polymer materials, a common method is to add a variety of thermal conductive fillers such as ceramic low-dimensional carbon nanomaterials and metal materials to the polymer.

[0004] Silver nanoparticles can weld adjacent clusters at temperatures significantly lower than the melting point of bulk silver (961.78°C). Therefore, they have excellent properties such as ultra-high thermal conductivity and electrical conductivity, which can be used to reduce contact thermal resistance. However, the thermal conductivity of pure silver nanoparticles after sintering is only 278.5W / (m·K), which is much lower than the thermal conductivity of bulk Ag. Therefore, in silver nanoparticle / polymer composites, a higher filling rate is required to achieve high thermal conductivity. These phenomena are caused by crystal defects and incomplete thermal conduction paths formed during the sintering process. However, a higher filling rate is contrary to the need for good printability and economic feasibility of thermal conductive pastes.

[0005] MXene is an emerging type of two-dimensional transition metal carbide that has attracted much attention due to its high hydrophilicity, excellent electrical conductivity and thermal conductivity. The general formula of its precursor is M n+1 X n T x (n=1, 2, 3), where M is an early transition metal (such as Sc, Ti, Zr), X is carbon or nitrogen, and T xSurface-specific functional groups. MXene surfaces contain a variety of functional groups (such as -OH and -F), resulting in excellent dispersibility and interfacial compatibility, properties not found in other two-dimensional materials. However, adjacent MXenes can accumulate and collapse, compromising their excellent thermal conductivity.

[0006] Existing patent CN 113105735 B discloses a highly thermally conductive polymer composite thermal conductive material. In this patent, due to the small thickness of the single-layer MXene, when the Ag loading is too high, it is easy to cause the MXene flakes to break, thereby affecting its thermal conductivity. Moreover, adding only a small amount of Ag@MXene to the polymer has limited improvement in the polymer's thermal conductivity. Summary of the Invention

[0007] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a method for preparing Ag@MXene composite high thermal conductivity slurry. The specific preparation steps are as follows:

[0008] (1) The precursor Ti3AlC2 powder was etched with hydrogen fluoride, and the precipitate was collected after etching. The precipitate was then centrifuged and washed with deionized water, and finally a layered MXene structure was obtained by freeze drying.

[0009] (2) The layered MXene obtained in step (1) is ultrasonically dispersed in deionized water to obtain a MXene dispersion (there is no special requirement for the amount of deionized water used in this step, as long as the layered MXene is fully dispersed).

[0010] (3) Dissolve AgNO3 in deionized water to obtain an AgNO3 solution (there is no special requirement for the amount of deionized water used in this step, as long as the AgNO3 is dissolved).

[0011] (4) The AgNO3 solution obtained in step (3) is slowly added dropwise to the MXene dispersion obtained in step (2), and the mixture is reacted in an ice bath for 1 to 3 hours after the addition of the AgNO3 solution. After the reaction is completed, the precipitate is collected, and then the precipitate is centrifuged and washed with deionized water. Finally, the precipitate is vacuum dried to obtain an Ag@MXene composite material.

[0012] (5) The Ag@MXene composite material obtained in step (4) is fully mixed with flaky silver powder and epoxy resin to prepare an Ag@MXene composite slurry.

[0013] Preferably, the mass ratio of layered MXene to AgNO3 in step (4) is layered MXene:AgNO3=50:1~5:1.

[0014] Preferably, the centrifugal washing is performed at a speed of 3000 to 4000 rpm and a centrifugal time of 1 to 3 minutes.

[0015] Preferably, the concentration of hydrogen fluoride in step (1) is 9 to 12 mol / L, 1 gram of Ti3AlC2 requires 10 to 30 ml of hydrofluoric acid for etching, the etching conditions are room temperature, and the etching time is 18 to 30 hours.

[0016] Preferably, in step (1), the centrifugal washing is performed until the pH of the upper layer liquid is greater than 6.

[0017] Preferably, the freeze-drying temperature in step (1) is -60 to -40°C, and the freeze-drying time is 20 to 28 hours.

[0018] Preferably, the particle size of the silver nanoparticles on the Ag@MXene composite material MXene in step (4) is 20 to 100 nm.

[0019] Preferably, in step (5), the mass ratio of the Ag@MXene composite material, the flaky silver powder and the epoxy resin is Ag@MXene composite material: flaky silver powder: epoxy resin = 1:60:39 to 5:60:35.

[0020] Application of the Ag@MXene composite high thermal conductivity slurry described in the present invention in electronic devices.

[0021] Beneficial effects of the present invention

[0022] (1) The MXene prepared in the present invention has a large number of active groups that can directly undergo reduction reaction with AgNO3, and the size of the obtained silver nanoparticles is small and controllable. At the same time, the MXene material itself has excellent thermal conductivity.

[0023] (2) The silver nanoparticles prepared by the present invention have a small particle size and can be sintered below 210°C, so that the flaky silver powder and MXene form a heat conduction path, reducing thermal resistance and thus greatly improving the thermal conductivity.

[0024] (3) The Ag@MXene composite thermal conductive slurry prepared in the present invention has high thermal conductivity, and its maximum thermal conductivity coefficient can reach 40.80 W / (m·K).

[0025] (4) The layered MXene in the present invention can be used as a carrier of silver nanoparticles due to its layered structure. In addition to being modified on the surface of MXene, silver nanoparticles can also enter the interlayer of MXene, playing a certain supporting role for MXene, thereby avoiding accumulation and collapse between MXenes, and the obtained hybrid filler has a synergistic reinforcing effect on the polymer matrix.

[0026] (5) The present invention adopts a multidimensional filler design consisting of three-dimensional microscale silver flakes, two-dimensional layered MXene and zero-dimensional silver nanoparticles. This combination provides greater potential for enhancing the thermal conductivity of the thermal conductive paste. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a scanning electron microscope image of the layered structure MXene in Example 2.

[0028] Figure 2 This is the scanning electron microscope image of Ag@MXene in Example 2.

[0029] Figure 3 This is a scanning electron microscope image of the sintering between silver and MXene through silver nanoparticles in Example 2. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below with reference to specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0031] Example 1

[0032] A preparation method and application of Ag@MXene composite high thermal conductivity slurry specifically includes the following steps:

[0033] (1) 1 g of the precursor Ti3AlC2 was slowly added to 10 ml of hydrogen fluoride. After stirring and etching at room temperature for 24 h, the precipitate was centrifuged and washed with deionized water at a centrifugal speed of 3000 rpm until the pH of the upper liquid was >6. The precipitate was then freeze-dried at -50 °C for 28 h to obtain a layered MXene.

[0034] (2) 0.5 g of the layered MXene obtained in step (1) was dispersed in deionized water by ultrasonication for 30 min to obtain a MXene dispersion.

[0035] (3) Dissolve 0.1 g of AgNO3 in deionized water to obtain an AgNO3 solution.

[0036] (4) The AgNO3 solution obtained in step (3) was slowly added dropwise to the MXene dispersion obtained in step (2). After the AgNO3 solution was added dropwise, the mixture was reacted in an ice bath for 3 h. The precipitate was centrifuged and washed at a centrifugal speed of 3000 rpm. Finally, the Ag@MXene composite material was obtained by vacuum drying at 80°C.

[0037] (5) The Ag@MXene composite material obtained in step (4) is fully mixed with flaky silver powder and epoxy resin to prepare an Ag@MXene composite slurry, wherein the mass ratio of the Ag@MXene composite material, flaky silver powder and epoxy resin is Ag@MXene composite material: flaky silver powder: epoxy resin = 1:60:39.

[0038] The prepared Ag@MXene composite slurry was cured at 200°C for 1 hour to test its thermal conductivity, and the thermal conductivity coefficient was found to be 17.17 W / (m·K).

[0039] Example 2

[0040] A preparation method and application of Ag@MXene composite high thermal conductivity slurry specifically includes the following steps:

[0041] (1) 1 g of the precursor Ti3AlC2 was slowly added to 20 ml of hydrogen fluoride. After stirring and etching at room temperature for 24 h, the precipitate was centrifuged and washed with deionized water at a centrifugal speed of 4000 rpm until the pH of the upper liquid was > 6. The precipitate was then freeze-dried at -60 °C for 24 h to obtain a layered MXene.

[0042] (2) 0.5 g of the layered MXene obtained in step (1) was dispersed in deionized water by ultrasonication for 30 min to obtain a MXene dispersion.

[0043] (3) Dissolve 0.15 g of AgNO3 in deionized water to obtain an AgNO3 solution.

[0044] (4) The AgNO3 solution obtained in step (3) was slowly added dropwise to the MXene dispersion. After the AgNO3 solution was added dropwise, the mixture was reacted in an ice bath for 2 h. The precipitate was centrifuged and washed at a centrifugal speed of 4000 rpm. Finally, the Ag@MXene composite material was obtained by vacuum drying at 80°C.

[0045] (5) The Ag@MXene composite material obtained in step (4) is fully mixed with flaky silver powder and epoxy resin to prepare an Ag@MXene composite slurry, wherein the mass ratio of the Ag@MXene composite material, flaky silver powder and epoxy resin is Ag@MXene composite material: flaky silver powder: epoxy resin = 3:60:37.

[0046] The prepared Ag@MXene composite slurry was cured at 210°C for 2h to test its thermal conductivity, and the thermal conductivity coefficient was found to be 40.14W / (m·K).

[0047] The Ag@MXene composite high thermal conductivity slurry prepared in this embodiment has the following microscopic morphology characteristics of MXene: Figure 1As shown in the figure, it can be seen that the MXene obtained after etching presents an obvious layered structure; the microscopic morphology characteristics of the Ag@MXene composite material are as follows Figure 2 As shown in the figure, it can be seen that silver nanoparticles are not only deposited on the surface of MXene, but also enter the interlayer of MXene; the scanning electron microscope image of the sintering of silver nanoparticles between silver and MXene is shown in Figure 3 As shown in the figure, it can be seen that multiple heat conduction paths are formed between MXene and flaky silver powder through the bridging of silver nanoparticles.

[0048] Example 3

[0049] A preparation method and application of Ag@MXene composite high thermal conductivity slurry specifically includes the following steps:

[0050] (1) 1 g of the precursor Ti3AlC2 was slowly added to 30 ml of HF. After stirring and etching at room temperature for 28 h, the precipitate was centrifuged and washed several times at a centrifugal speed of 3500 rpm until the pH of the upper liquid was > 6. It was then freeze-dried at -40 °C for 20 h to obtain a layered MXene.

[0051] (2) 0.5 g of the layered MXene obtained in step (1) was dispersed in deionized water by ultrasonication for 30 min to obtain a MXene dispersion.

[0052] (3) Dissolve 0.01AgNO3 in deionized water to obtain an AgNO3 solution.

[0053] (4) The AgNO3 solution obtained in step (3) was slowly added dropwise to the MXene dispersion. After the AgNO3 solution was added dropwise, the mixture was reacted in an ice bath for 1 h. The precipitate was centrifuged and washed with deionized water at a centrifugal speed of 3500 rpm. Finally, the Ag@MXene composite material was obtained by vacuum drying at 80°C.

[0054] (5) The Ag@MXene composite material obtained in step (4) is fully mixed with flaky silver powder and epoxy resin to prepare an Ag@MXene composite slurry, wherein the mass ratio of the Ag@MXene composite material, flaky silver powder and epoxy resin is Ag@MXene composite material: flaky silver powder: epoxy resin = 5:60:35.

[0055] The prepared Ag@MXene composite slurry was cured at 220°C for 3 hours to test its thermal conductivity, and the thermal conductivity coefficient was found to be 18.69 W / (m·K).

[0056] Comparative Example 1

[0057] As a comparison, the difference between this example and Example 2 is that the MXene is not modified with nanosilver. The specific steps are as follows:

[0058] (1) 1 g of the precursor Ti3AlC2 was slowly added to 20 ml of hydrofluoric acid. After stirring and etching at room temperature for 24 h, the precipitate was centrifuged and washed several times at a centrifugal speed of 4000 rpm until the pH of the upper liquid was > 6, and then freeze-dried at -60 °C for 24 h to obtain multilayer MXene.

[0059] (2) The multilayer MXene obtained in step (1) is fully mixed with flaky silver powder and epoxy resin to prepare a MXene composite slurry, wherein the mass ratio of MXene, flaky silver powder and epoxy resin is MXene: flaky silver powder: epoxy resin = 3:60:37.

[0060] The prepared MXene composite slurry was cured at 210°C for 2 hours to test its thermal conductivity. The thermal conductivity was 5.164 W / (m·K), which was significantly lower than that of Example 2. This is because without the bridging effect of the silver nanoparticles, the MXene and the flaky silver powder could only form a thermal conduction path through simple physical contact, which greatly reduced the thermal conductivity.

[0061] Comparative Example 2

[0062] As a control, this embodiment differs from embodiment 2 in that no Ag@MXene composite material is added. The specific steps are as follows:

[0063] The thermal conductive silver paste is prepared by fully mixing the flaky silver powder and the epoxy resin, wherein the mass ratio of the flaky silver powder to the epoxy resin is: flaky silver powder:epoxy resin=63:37.

[0064] The prepared thermally conductive silver paste was cured at 210°C for 2 hours to test its thermal conductivity. The thermal conductivity was 4.653 W / (m·K), which was significantly lower than that of Example 2. This is because the flaky silver powder can only form a thermal path through simple physical contact, and the thermal conductivity of silver is lower than that of MXene, resulting in lower thermal conductivity.

[0065] Comparative Example 3

[0066] As a comparison, this embodiment differs from embodiment 2 in that no flaky silver powder is added. The specific steps are as follows:

[0067] (1) 1 g of the precursor Ti3AlC2 was slowly added to 20 ml of hydrofluoric acid. After stirring and etching at room temperature for 20 h, the precipitate was centrifuged and washed several times at a centrifugal speed of 4000 rpm until the pH of the upper liquid was > 6. The precipitate was then freeze-dried at -60 °C for 24 h to obtain multilayer MXene.

[0068] (2) 0.5 g of the multilayer MXene obtained in step (1) was dispersed in deionized water by ultrasonication for 30 min to obtain a MXene dispersion.

[0069] (3) Dissolve 0.15 g of AgNO3 in deionized water to obtain an AgNO3 solution.

[0070] (4) The AgNO3 solution obtained in step (3) was slowly added dropwise to the MXene dispersion obtained in step (2). After the AgNO3 solution was added dropwise, the mixture was reacted in an ice bath for 2 h. The precipitate was centrifuged and washed at a centrifugal speed of 4000 rpm. Finally, the Ag@MXene composite material was obtained by vacuum drying at 80°C.

[0071] (5) The Ag@MXene composite material obtained in step (4) is fully mixed with epoxy resin to prepare an Ag@MXene composite slurry, wherein the mass ratio of the Ag@MXene composite material to the epoxy resin is Ag@MXene composite material:epoxy resin=3:97.

[0072] The prepared Ag@MXene composite slurry was cured at 210°C for 2 hours to test its thermal conductivity. The thermal conductivity was 0.987 W / (m·K), which was significantly inferior to that of Example 2. This was because the amount of Ag@MXene composite material added was small, and most of the Ag@MXene composite material existed independently in the epoxy resin matrix. Only a small portion of the MXene could form a thermal conduction path through the silver nanoparticles, resulting in lower thermal conductivity.

Claims

1. A method for preparing an Ag@MXene composite high thermal conductivity slurry, characterized by: The following steps are involved: (1) The precursor Ti3AlC2 powder is etched with hydrogen fluoride, the precipitate is collected after stirring and etching, and then the precipitate is centrifuged and washed with deionized water, and finally a layered MXene structure is obtained by freeze drying; (2) dispersing the layered MXene prepared in step (1) in deionized water by ultrasonication to obtain a MXene dispersion; (3) dissolving AgNO3 in deionized water to obtain an AgNO3 solution; (4) The AgNO3 solution obtained in step (3) is slowly added dropwise to the MXene dispersion obtained in step (2), and the reaction is carried out in an ice bath for 1 to 3 hours after the addition of the AgNO3 solution. After the reaction is completed, the precipitate is collected, and then the precipitate is centrifuged and washed with deionized water. Finally, the precipitate is vacuum dried to obtain an Ag@MXene composite material; (5) The Ag@MXene composite material obtained in step (4) is fully mixed with flaky silver powder and epoxy resin to prepare an Ag@MXene composite slurry; The mass ratio of the Ag@MXene composite material, the flaky silver powder and the epoxy resin in step (5) is Ag@MXene composite material: flaky silver powder: epoxy resin = 1:60:39~5:60:

35.

2. The method for preparing the Ag@MXene composite high thermal conductivity slurry according to claim 1, characterized in that: In step (4), the mass ratio of layered MXene to AgNO3 is layered MXene:AgNO3=50:1~5:

1.

3. The method for preparing the Ag@MXene composite high thermal conductivity slurry according to claim 1, characterized in that: In step (1) and step (4), the centrifugal washing is performed at 3000-4000 rpm and the centrifugal time is 1-3 min.

4. The method for preparing the Ag@MXene composite high thermal conductivity slurry according to claim 1, characterized in that: In step (1), the concentration of hydrogen fluoride is 9-12 mol / L, and 10-30 ml of hydrofluoric acid is required for etching per gram of Ti3AlC2. The etching conditions are room temperature and the etching time is 18-30 h.

5. The method for preparing the Ag@MXene composite high thermal conductivity slurry according to claim 1, characterized in that: In step (1), centrifuge and wash until the pH of the upper layer is > 6.

6. The method for preparing the Ag@MXene composite high thermal conductivity slurry according to claim 1, characterized in that: In step (1), the freeze-drying temperature is -60 to -40°C, and the freeze-drying time is 20 to 28 hours.

7. The method for preparing the Ag@MXene composite high thermal conductivity slurry according to claim 1, characterized in that: In step (4), the particle size of the silver nanoparticles on the Ag@MXene composite material MXene is 20~100nm.

8. Use of the Ag@MXene composite high thermal conductivity slurry prepared according to any one of claims 1 to 7 in electronic devices.

Images