Excellent Heat Dissipation Research Articles

Reinforcement of microwave absorption and thermal conductivity of polydimethylsiloxane achieved by metal-organic framework-derived carbon nanotube/boron nitride flake heterogeneous structure

Due to the rapid advancement of electronic devices towards miniaturization, high-integration, multi-functionality, high-power, and high-frequency, it is necessary to design thermal interface materials (TIMs) that possess exceptional thermal conductivity as well as good capabilities for absorbing electromagnetic waves. In this report, carbon nanotubes (CNTs) containing cobalt (Co) nanoparticles have been in-situ grown on the surfaces of boron nitride flakes (BNFs) using the Co nanoparticles as catalysts which formed by the high-temperature pyrolysis and reduction of zeolite-imidazolate skeleton. Then, a multifunctional heterogeneous structure of Co@CNT/BNFs has been developed with tunable microwave absorption (MA) property and high thermal conductivity, which can be applied to enhance the MA performance and thermal conductivity of polymers simultaneously. The minimum reflection loss can reach −46.6 dB and a broad absorption bandwidth of 5.92 GHz can be obtained when adjusting the content of Co@CNT/BNFs in the absorbers. Furthermore, the thermal conductivity of the polydimethylsiloxane measured using the transient hot-wire apparatus is 0.72 W/(m·K) when the content of Co@CNT/BNFs is 30 wt%, exhibiting excellent heat dissipation performance in thermal management. This work is significant for investigating MA packaging and high thermally conductive TIMs for the electronic devices.

Synthesis of novel Stachytarpheta jamaicensis flower liked hexagonal boron nitride nanoribbons (SJF-BNNBs) to efficiently improve the thermal/mechanical/electrical properties of flexible polyimide films

Heat dissipation has become a bottleneck restricting large-scale integration and flexible electronic technologies. This study reports a novel fabrication strategy to prepare flexible stachytarpheta jamaicensis flower-like hexagonal boron nitride nanoribbons (SJF-BNNBs) and their composite films with polyimide (PI). The effect of synthesis conditions on the morphology of SJF-BNNBs was investigated, and the growth mechanism was proposed. The in-plane and through plane thermal conductivities of the 4 wt% SJF-BNNBs/PI composite film reach 5.98 W m−1 K−1 and 0.79 W m−1 K−1, which are 3047 % and 316 % higher than those of the pure PI film, respectively. The in-plane and through plane thermal conduction enhancement efficiencies reach 761.8 % and 78.9 %, respectively. The tensile strength of the composite film is 61.7 % higher than that of pure PI, and maintains excellent electrical insulating and thermal stability properties. Infrared imaging tests verified the excellent heat dissipation performance of the composite film as a thermal interface material and a flexible copper clad laminate substrate, where the operating temperature of device could be reduced by 17.3 °C. To the best of our knowledge, SJF-BNNBs outperform the most efficient thermally conductive electrically insulating filler and are to break the overcome of polymer composites in heat dissipation applications.

A novel tree -like bionic structure for liquid-cooled lithium-ion battery plates

To maintain the optimal operating temperature range for the power batteries of new energy vehicles, this paper proposes a novel tree-structured channel cold plate. An orthogonal experimental approach was employed to investigate the effects of inlet flow rate m, inlet channel quantity n, channel width d, and hierarchy ratio α on battery temperatures Tmax, standard temperature difference Tσ, and pressure drop ΔP. Non-dominated sorting genetic algorithm II (NSGA-II) was utilized to obtain an optimized solution set. The results reveal that the tree-like cold plate configuration including m = 15 g/s, n = 7 and 8, d = 3 mm, and α = 1:2:1 demonstrates superior performance. Thus, the developed cold plate was further compared with the conventional straight-through cold plate design. The results indicate that the proposed tree-like cold plate exhibits the maximum decreases of 13.94% in Tmax, 52.94% in Tσ, and 61.5% in ΔP. The most significant improvement in the composite indicator PEC was 89%. In conclusion, the tree-like channel cold plate developed in this study provides excellent heat dissipation capability for power batteries, offering valuable insights for the thermal design of battery liquid cooling systems.

Thermally conductive, electrically insulating, and radiative cooling PVDF/BNNS/Al2O3/cordierite nanocomposites

For now, the introduction of fillers with highly intrinsic thermal conductivity (TC) into polymers is the most effective way to prepare composites with excellent heat dissipation capability. However, reducing the filler loading without lowering the TC is the most challenging. In this article, patterned electrospinning and hot pressing were employed to prepare thermally conductive and electrically insulating polyvinylidene fluoride (PVDF)-based composites containing 20 wt% boron nitride nanosheets (BNNSs) as the dominant filler and 5 wt% Al2O3 nanopowders as the auxiliary filler. We have proven “1 + 1>2″ in terms of enhancing the TC of composites at nanoscale by the synergistic effect of nanosheet and nanopowder. The results showed that the in-plane TC (8.55 W/(m·K)), volume resistivity (1.56 × 1015 Ω cm), and breakdown strength (406.2 kV/mm) of the composites were improved by 4759.1 %, 649.0 %, and 34.1 % compared with the neat polymer, respectively. Furthermore, the potential application of such composites in contact heat dissipation and radiative cooling was demonstrated by the experiment of integrating cordierite particles with high infrared radiation onto the films.

Fabrication and heat dissipation performance of diamond/Cu composite with diamond bars inserted in the normal direction

In this paper, a new type of diamond/Cu composite with diamond bars inserted in the normal direction is designed and prepared by vacuum brazing. In order to reduce the negative effect of the low thermal conductivity of Cu-Sn-Ti solder, diamond particles were added into the solder area. The microstructure, thermal conductivity, and heat dissipation performance of the diamond/Cu composite under water-free and water-cooling conditions were studied and compared. Besides, the heat dissipation mechanism of the composite was explored through finite element analysis. The results show that the diamond bars and diamond particles can be connected well by the CuSnTi solder, and the diamond particles scatter in the solder area. The TC tests show that the sample with 2000 mesh diamond particles has the highest TC (515.25 W/(m·K)). Besides, both the heating experiments on the electronic heating platform and the actual heat dissipation performance under water-cooling conditions affirm the excellent heat dissipation effect of the composite with 2000 mesh diamond particles. In conclusion, the diamond/Cu composite with diamond bars inserted vertically possess an excellent structural design, which is promising in heat dissipation material for electronic devices.

Construction of thermally conductive and insulating fibers of BN nanosheet/aramid nanofiber composites with high-temperature resistance via sol-gel wet spinning

With the intensification of global warming and the occurrence of extremely hot weather, there is an urgent need for textiles that can effectively regulate temperature. Using amino-functionalized boron nitride nanosheets (K-BNNSs) and aramid nanofibers (ANFs) as materials, the well-oriented thermally conductive insulating textile fibers with “lotus root” structure were directly prepared by sol–gel wet spinning process. The axial thermal conductivity of a single fiber can be as high as 22.4 W/(m·K), and has an excellent tensile fracture strength (176.6 MPa). Thermal infrared imaging revealed that the fibers woven into textiles had a more significant heat dissipation capacity than commercial cotton fabrics. The fiber obtained by this low-cost preparation method provides a cooling textile with excellent heat-dissipation ability and has wide application prospects in emerging textiles.

Highly conductive carbon nanotubes-boron nitride-thermoplastic polyurethane composite thin films with ultra broadband and efficient electromagnetic interference shielding up to 110 GHz and heat dissipation abilities

The miniaturization and integration of electronic devices have led to an increased accumulation of heat, which can disrupt normal functioning. Their functionalities are also severely affected when they are exposed to the abundant electromagnetic interference (EMI) resulting from the rapid development of fifth-generation telecommunication technology extended to mmWaves and sixth-generation telecommunication frequencies up to 110 GHz. Therefore, it is urgent to develop composite materials with excellent EMI shielding effectiveness and heat dissipation abilities. Herein, we have fabricated an all-in-one thin film composite using carbon nanotubes (CNT), boron nitride (BN), and thermoplastic polyurethane (TPU) through a layer-by-layer casting method to create a composite supported by hydrogen bonding with impressive EMI shielding and heat dissipation properties. The high electrical conductivity of the CNT-BN-TPU composite resulted in the highest EMI shielding effectiveness, ranging from 90.66 dB in Ka-band to 79.8 dB in W-band, at a thickness of 100 μm, with absorption efficiency of 83.07 % at 34 GHz and 80.85 % at 100 GHz, respectively. The composite demonstrated excellent heat dissipation, thanks to its outstanding out-of-plane thermal conductivity, which reached 1.971 W/mK. We believe that our proposed method for producing an all-in-one composite thin film with excellent EMI shielding and thermal management capabilities could be a useful approach for the next generation of smart electronic devices.

Enhancement of thermal conductivity and insulation of silicone thermal interface material through surface modification and synergistic effects of nanofillers for thermal management of electronic devices

Thermal interface materials (TIMs) play an irreplaceable role in highly integrated microelectronic devices. In this work, the addition of acidified carbon nanotubes modified by 3-aminopropyl triethoxysilane (KH550) had an effective enhancement to the thermal conductivity, thermal stability, and electrical insulation performance of silicone grease. On this basis, multi-filled silicone grease composites with better thermal conductivity and electrical insulation were prepared by introducing zinc oxide (ZnO) and Graphene nanoflakes (GNFs). The thermal conductivity of silicone grease achieved 1.438 W m−1 K−1, while the volume resistivity still exceeded 1013 Ω·cm. Additionally, the study explored the impact of varying filler parameters, temperature, and contact pressure on the interface thermal contact resistance of silicone grease. The best performance silicone grease applied to the cooling of the high-power LED exhibited excellent heat dissipation. This work presented a reference for the design and development of low cost, high performance TIMs.

Vitrimeric phase change material facilitating 3D-structured boron nitride network for reliable thermal conductive interface materials

Phase change materials (PCMs) shows great promise as thermal interface materials (TIMs) due to their compliance and thermal management properties from solid-liquid phase transition characteristics. However, the significantly reduced thermal conductivity resulting from that randomly dispersed thermal conductive fillers susceptible to localized volume change by solid-liquid phase transition deteriorates the reliable heat transfer of TIM but is often overlooked. In this work, 3D-structured network of boron nitride (BN) fillers is created in vitrimeric PCM (vPCM) consisting of dynamic covalent crosslinked polyolefin elastomer (POE)/paraffin wax (PW) blends. The resulted composites with interconnected BN network show a through-plane thermal conductivity (κ⊥) of 3.08 W m−1 K−1 at 29.8 vol% BN. Significantly, the composites can keep the BN network continuous when heated, and remain κ⊥ of about 1.4 W m−1 K−1 after the solid-liquid phase transition of PW, which ensures reliable heat transfer when achieving thermal management by melting endotherm of PW. Moreover, the composites conform to the surface topography of sandwiching surfaces through solid plasticity under low stress when the crosslinked network rearranges via the exchange of dynamic covalent bonds activated by the melting of POE, reducing the thermal contact resistance. When the composites are used as TIM through thermally triggered reconfigurable package procedures at 80 °C and 50 kPa, the heat dissipation is better than a commercial thermal pad with κ⊥ of 3.86 W m−1 K−1. Vitrimeric PCM facilitates reliable 3D-structured BN network and thermally triggered conformability, paving a promising way for high-performance TIM with excellent heat dissipation.

Fabrication of boron nitride reinforced carboxymethyl modified lignin-based re-crosslinkable hydrogel with excellent heat dissipation ability

In this work, a series of re-crosslinkable hydrogels comprising carboxymethylated lignin, PVA and 3-aminophenylboronic acid (3-ABA) was successfully synthesized. Incorporation of polydopamine (PDA) coated boron nitride (PDA@BN) endowed the hydrogel with significantly improved heat dissipation ability, mechanical strength and swelling resistance. The hydrogel containing 20 % of PDA@BN, namely Gel-20 %BN displayed an initial degradation temperature of 131 ℃ and a high thermal conductivity of 3.74 W/m·K, surpassing a plethora of different biobased hydrogels. Gel-20 %BN maintained stable morphology even under continuous heating at 200 ℃ for 15 min and exhibited low surface temperatures without undergoing melting or decomposition, thus demonstrating remarkable heat dissipation capability. The re-crosslinked hydrogel, referred to as Re.Gel-20 %BN, retained similar performance to Gel-20 %BN, maintaining excellent heat dissipation characteristics and stability at 130 ℃ over an extended period. Further investigation is warranted to explore degradation or recovery methods of this hydrogel in reservoir conditions, aiming to minimize the environmental impact of petroleum extraction and contribute to a greener and more sustainable oil production process.

Highly reflective TiO2 layer on AlN substrate: Enabling high quality laser lighting

Phosphors in glass films (PiFs) is considered ideal conversion materials for laser lighting, but heat dissipation issue is the main challenge limiting its development. Therefore, it is urgent to find more excellent heat dissipation materials. Herein, we proposed to use AlN with high thermal conductivity as the substrate, and innovatively introduced TiO2 coating to improve the interface reflection ability and solve the possible problems of shedding and cracking. After a series of optimizations, the LSN PiG-TiO2-AlN (PTA) color converter obtained a high thermal conductivity of 29W m−1k−1 and a low surface temperature. At an input power of 5.2W, the luminous efficiency can reach 175 lm/W and the relative initial intensity can still be maintained by 95.3% at 200 °C. Benefiting from the extremely strong heat dissipation capacity of the AlN substrate, the LSN PTA color converter maintains its relative luminous intensity at 95 % of the initial intensity after 24 h of continuous illumination, which is the best value recorded so far. In addition, LSN PTA is combined with CaAlSiN3:Eu2+ phosphor to achieve high-quality white light with a CRI of 82.5. The above results indicate that LSN PiG-TiO2-AlN color converters have a promising research prospect in the field of laser lighting.

Carboxylated cellulose composite film fabricated via layer‐by‐layer self‐sssembly for thermal management material with ultra‐high thermal conductivity

AbstractWith the development of 5G equipment, aerospace, sensors, thermal management devices and other fields in the direction of high power, high performance and miniaturization, the heat released during usage increases significantly, leaving great application prospects for heat dissipation materials. In spite of great attention paid to film materials due to their light weight and flexibility, they have the obvious disadvantage of poor thermal conductivity. In this work, carboxylated cellulose (CNF‐C)/dopamine‐coated nickel‐coated graphene (PDA‐Ni@GNS) composite films with high in‐plane thermal conductivity (in‐plane TC) have been fabricated by a simple vacuum‐assisted filtration method. In the prepared composite films, the flaky packing layers were found to be stacked orderly and form an excellent thermally conductive network, resulting in an increase in in‐plane TC by 322.1% (sample W4) as compared with that of neat films. By comparing the in‐plane TCs of the composite films with that of a commercial gasket, it was readily seen that the present composite films had fairly excellent heat dissipation properties. The composite exhibits not only sufficiently high in‐plane TC and tensile strength of 149.02 MPa but also exhibits hydrophobic property, imparting the composite films good working stability under extreme conditions, which ensured of their potential applications in thermal management materials.Highlights The introduction of Ni promotes the construction of heat conduction path. High in‐plane TC is obtained through layer‐by‐layer self‐assembly. The modification of filler enhanced the mechanical properties of the films. The modification of fillers led to the hydrophobicity of the film. The introduction of PDA made the films have insulating properties.

A novel flexible composite phase change material applied to the thermal safety of lithium-ion batteries

Large deformation of lithium-ion batteries (LIBs) under mechanical load can cause internal short circuit of the battery. Further, the LIBs generate a large amount of heat during the rapid charging and discharging process. The internal short circuit and heat accumulation in the battery can lead to explosion or fire, so mechanical damage and thermal runaway are the two major safety issues that hinder the practical application of LIBs. To this end, we have designed a new type of flexible composite phase change material (FCPCM) with dual functions of anti-extrusion and heat absorption. Firstly, paraffin wax (PW) is adsorbed in the pores of expanded graphite (EG) to obtain EG/PW composite phase change material (CPCM). Then, the powdered PW/EG and flake copper powder (FCP) as the heat conductive filler are coated in a thermoplastic elastomer (TPE) for secondary encapsulation, and the FCPCM with a high latent heat (137 J/g) is obtained. TPE not only reduces the leakage rate of PW but also improves the deformation capacity of CPCM and absorbs extrusion energy. As a filler with high thermal conductivity, FCP can effectively improve the thermal conductivity of the FCPCM. When the FCP content is 5 wt%, the thermal conductivity is as high as 3.357 W/mK. In the battery extrusion experiment, when the loading displacement reaches 13 mm, the battery does not suffer mechanical damage and internal short circuit. Next, the prepared FCPCM is applied to the thermal management of a battery. Experiments and simulations were combined to investigate the heat dissipation capacity of the FCPCM for battery at different discharge rates and different ambient temperatures, and 3 cycles at the maximum discharge rate (5C) and an ambient temperature of 30 °C were able to meet the requirements for practical use. The results verify that FCPCM exhibits immense application potential in the thermal management of batteries. Overall, we provide a new method for the design of CPCMs with excellent mechanical extrusion energy absorption and heat dissipation performance.

Growth of polyaniline nanowire arrays on boron nitride microrods enables high‐efficient thermal transport

AbstractThe rapid development of flexible conductive materials has promoted the research on conductive polymer (CP)‐based materials. However, CPs have relatively low thermal conductivity (TC), which can result in severe heat dissipation problems for device applications. In this work, core–sheath structured polyaniline@boron nitride (BN@PANI) composites were prepared by in‐situ growth strategy, in which PANI nanowire arrays were uniformly anchored to the surface of BN microrods. Thanks to the particular structure, the as‐prepared BN@PANI composite shows excellent thermal management capabilities. Specifically, the TC of the BN@PANI composite is 4.32 W/m·K at low BN loading of 10 wt%, which is almost 17.8 times that of pure PANI. Moreover, the excellent heat dissipation performance is intuitively presented through infrared imaging technology. Impressively, the PANI nanowire arrays are vertically arranged on the BN surface to form a conductive pathway, which results in conductivity comparable to pure PANI. This work broadens the ideas for preparing high‐performance CP‐based composites by using insulating fillers.Highlights Core–sheath structured BN@PANI composites were prepared by an in‐situ growth strategy. The thermal conductivity of composite was 4.32 W/m·K at 10 wt% BN loading. The introduction of BN had little effect on the conductivity of PANI. The BN@PANI composites possessed excellent thermal management capability. This work contributes to understanding heat transport in conductive polymers.

Multi-objective optimization design of power pack structures based on floating projection topology optimization

Battery packs are vital components for storing and releasing energy. However, during driving, the intensity of heat emission and mechanical performance of electric vehicles are interrelated but conflicting indicators. To address this problem, this study topologically optimizes the power pack support structure with multiple objectives of minimizing compliance and heat dissipation, aiming to achieve a comprehensive and integrated design scheme. A floating projection topology optimization (FPTO) method is proposed, which normalizes the objectives of structural compliance and heat dissipation and derives the sensitivity. FPTO demonstrates superior objective function values and smoother topology configuration compared to the solid isotropic material with penalization (SIMP) method. Finally, the proposed method is applied to the power pack support structure. The results demonstrate that the method obtains a design solution with excellent mechanical performance and high heat dissipation performance with a suitable trade-off. The lightweight design of the overall structure of the battery pack is achieved.

28.02 W LD side-pumped CW laser operated at 2.8 µm in YSGG/Er:YSGG/YSGG crystal.

We demonstrated a 978 nm laser diode (LD) side-pumped YSGG/Er:YSGG/YSGG composite crystal with a size of Ф 3 mm × 65 mm and continuous-wave (CW) mode. By optimizing resonator length and output mirror transmittance, a maximum output power of 28.02W is generated, corresponding to slope efficiency of 17.55% and optical-optical efficiency of 12.29%, respectively. The thermal focal lengths are obtained by resonator stability condition. The laser wavelength is centered near 2.8 µm. Moreover, the beam quality factors M x2/M y2 are fitted to be 8.14 and 7.35, respectively. The above results indicate that a high-performance 2.8µm CW laser can be achieved by LD side-pumped YSGG/Er:YSGG/YSGG composite crystal with excellent heat dissipation ability, which promotes effectively the development and applications of the mid-infrared solid-state lasers.

Thermal resistance optimization of ultra-thin vapor chamber based on data-driven model and metaheuristic algorithm

The ultra-thin vapor chamber(UTVC) is extensively utilized across various fields due to its excellent heat dissipation performance and good temperature uniformity. The data-driven modeling approach is well suited to predict the thermal resistance of the UTVC due to its great flexibility and accuracy. In this paper, a novel approach is proposed to optimize the UTVC thermal resistance, which combines the radial basis function neural network(RBFNN) model with an improved adaptive differential fish swarm evolution algorithm(ADFEA). The mean square error of the RBFNN model was 0.00016 on the training set and 0.00027 on the test sets, which indicates that the model is able to accurately predict the thermal resistance of the UTVC. The data are obtained from experiments on a mesh wick UTVC with dimensions of 124 × 14 × 1 mm. A novel optimization algorithm, ADFEA, has been designed to enhance optimization capability and convergence accuracy. This algorithm combines differential algorithm and artificial fish swarm algorithm, incorporating a parameter adaptation mechanism. The optimal operating parameters of the UTVC are obtained by ADFEA optimization and the accuracy of the optimized results is verified by experiment. The proposed optimization method provides new insights for the design and optimization of UTVC.

Effect of yttrium nitrate coating on the vat photopolymerization forming process and sintering properties of aluminum nitride ceramics

In this study, a ball-milling method was successfully used to coat yttrium nitrate on the surface of aluminum nitride (AlN) powder and the effects of yttrium nitrate content on the AlN powder particle size, viscosity and curing behavior of the AlN suspension, and performance and microstructure of the sintered AlN bodies were investigated. The results indicated that the AlN powder surface coating significantly reduced the viscosity of the suspension and enhanced the cure depth while increasing the powder particle size, which in turn reduced the stability of the suspension. By studying the performance of sintered bodies, it was found that as the yttrium nitrate content increased, the AlN thermal conductivity and flexural strength initially increased and then decreased. Microstructural analysis results revealed that the second phase in samples with 9.23 and 14.49 wt% yttrium nitrate exhibited an island-like distribution, whereas in samples with 19.18 wt% yttrium nitrate, the second phase exhibited a continuous distribution. Finally, the heat-dissipation performance of AlN components with different structures was also studied, and testing was conducted on the driving chip of a 3D printing device. The results indicated that complex-structured AlN ceramic components exhibited an excellent heat-dissipation performance.

Construction of alumina framework with a sponge template toward highly thermally conductive epoxy composites

AbstractCeramic‐based polymer composites are commonly utilized as thermal management materials due to their high thermal conductivity and electrical insulation properties. One efficient method to enhance the thermal conductivity of these composites is by constructing a three‐dimensional thermal conductive network within the polymer matrix. In this study, alumina was coated onto the surface of polyurethane (PU) foam, followed by high‐temperature removal of the PU foam and sintering of the alumina sheets to obtain a continuous alumina framework. Epoxy resin was then infiltrated into this alumina framework to fabricate highly thermally conductive EP/f‐Al2O3 composites. The EP/f‐Al2O3 composite achieved a thermal conductivity of 2.44 W m−1 K−1 when the filler content of 26.8 vol%, representing a 400% improvement compared to EP/Al2O3 composite with randomly dispersed fillers, and a remarkable 1180% enhancement compared to epoxy resin. Infrared thermal imaging also confirmed the excellent heat dissipation capability of the EP/f‐Al2O3 composites. Overall, this research presents an effective method for producing highly thermally conductive and electrically insulating composites that can be used in electronic thermal management applications.Highlights Fabrication of porous Al2O3 frameworks/epoxy composites. Porous Al2O3 frameworks were fabricated by polyurethane foam template. The obtained EP/f‐Al2O3 composite exhibited excellent thermal conductivity.

Ti-B-O System for Catalyzing Boron Nitride Nanotube Growth.

Chemical vapor deposition (CVD) stands out as the most promising method for cost-effective production of high-quality boron nitride nanotubes (BNNTs). Catalysts play a crucial role in BNNT synthesis. This work delves into the impact of oxygen (O) on Ti-based catalysts during the CVD growth of BNNTs. In contrast to the B/TiB2 nanoparticles (NPs) and B/TiN NPs systems, the oxygen-containing precursor B/TiO2 NPs remarkably catalyzes the growth of high-quality and high-purity BNNTs across a wider range of synthesis parameters. Subsequent analyses reveal that TiBO3 acts as an active catalyst, facilitating BNNT growth in Ti-based catalyst systems. Moreover, the nanocomposite film synthesized from BNNTs and PVDF-HFP exhibits excellent mechanical properties and heat dissipation capabilities. Utilizing the nanocomposite film as a thermal interface material effectively enhances the heat dissipation for a 5 W light-emitting diode (LED) chip. Consequently, our research confirms the effectiveness of the Ti-B-O system in catalyzing BNNT growth.