Three-dimensional Boron Research Articles

Using Three-Dimensional Carbon and Boron Nitride to Improve the Properties of Polyethylene Oxide-Based Solid-State Electrolytes for Li Ion Batteries

Polyethylene oxide (PEO)-based solid-state electrolyte (SSE) is attractive due to its excellent adhesion with electrodes and good processability. However, lithium dendrites easily penetrate PEO because of their soft nature, which results in inferior battery performance and safety issues. In this talk, we will discuss the development of 3D (insulating) amorphous carbon and 3D amorphous BN to improve the properties of polyethylene oxide (PEO)-based solid-state electrolytes for Li ion batteries.For the 3D amorphous carbon, we developed a novel self-healing PEO-based SSE is prepared by incorporating 2 wt% amorphous three-dimensional carbon (3DC). This SSE possesses suitably low electronic conductivity for battery applications (on the order of 10^−9 S/cm), which is five orders of magnitude lower than its ionic conductivity (10−4 S/cm) at 60 °C. In addition, the improved fluidity and strong adhesion between the 3DC and the PEO matrix contribute to the self-healing ability of SSE, which will repair the cracks of SSE formed during battery cycling. Moreover, this SSE shows enhanced ionic and thermal conductivities and mechanical strength, suppressing the formation and growth of lithium dendrites. As a result, this SSE exhibits excellent electrochemical stability, achieving 5000 h of stable cycles in lithium symmetric cell (0.1 mA cm−2, 0.1 mAh cm−2) and 850 long-term stable cycles for the LFP//Li full cell at 1 C (0.31 mA cm−2).For the 3D amorphous BN, we have developed the first synthesis of powdery hexagonal boron nitride (h-BN). This synthesis introduces a novel NaCl-glucose assisted strategy to synthesize micron-sized 3D h-BN with a honeycomb-like structure. When incorporated into polyethylene oxide-based electrolytes for Li-ion batteries, 5 wt% of 3D h-BN significantly enhances ionic conductivity and mechanical strength. Consequently, this composite electrolyte demonstrates superior electrochemical stability; it delivers 300 h of stable cycles in the lithium symmetric cell at 0.1 mA cm-2 and retains 89 % of discharge capacity (138.9 mAh/g) after 100 cycles at 1 C in the LFP//Li full cell.These two approaches reveal that 3DC and 3D h-BN can be used to improve the properties of PEO-based electrolytes of Li-ion batteries.

High thermal conductivity and low dielectric loss of three-dimensional boron nitride nanosheets/epoxy composites

Electronic power devices are moving towards high frequency, high integration, and high power, which urgently needs to develop high thermal conductive encapsulating insulation materials to improve the heat dissipation of electronic devices. Herein, we propose to modify the commercialized encapsulating materials of epoxy resin (EP) by incorporating three-dimensional hydroxylated boron nitride nanosheets (3D-BNNSs). The cryogel and vacuum freeze-drying techniques are employed to prepare the 3D-BNNSs using agarose. The results show that the constructed high thermal conductive structure of 3D-BNNSs can effectively enhance the thermal conductivity of EP and reduce the interfacial thermal resistance between BNNSs fillers. The thermal conductivity of 3D-BNNSs/EP composites with 33.03 wt% BNNSs reach 2.54 W/(m·K), which is 13.11 times higher than that of EP (0.18 W/(m·K)). Meanwhile, the resultant composites remain outstanding electrical insulation and dielectric properties. Because agarose contains numerous hydroxyl groups that can form hydrogen bonds with the hydroxyl groups on the surface-functionalized BNNSs, hydrogen bonding can lead to strong intermolecular interactions, which is conductive to accelarate phonon transport. Additionally, agarose can cross-link with the molecular chains of epoxy, impeding the movement of molecular chain segments and resulting in composites with low dielectric loss at high frequencies. This study demonstrates that the 3D-BNNSs/EP composites have great potential for application in thermal management of electronic components.

Preparation of three dimensional boron nitride-aluminum oxide dual thermal network resin-based composite materials and their performance study

With the gradual miniaturization and integration of electronic devices, the design and development of new high thermal conductivity polymer-based composite materials are crucial for enhancing the performance of modern electronic devices. In this study, three-dimensional boron nitride (3D-BN) aerogels with vertically aligned structures were prepared using the ice templating method, serving as the primary thermal conductive network. Subsequently, aluminum oxide (Al2O3)/epoxy resin (EP) nanofluids were infiltrated into the aerogel’s air pores using vacuum impregnation. The Al2O3 particles in contact with each other formed the secondary thermal conductive network. Thus, a 3D BN-Al2O3/EP composite material with a dual thermal conductive network structure was successfully fabricated. The composite material exhibited a high thermal conductivity coefficient of 1.077 Wm−1K−1 when loaded with 17.67 wt% BN and 26.23 wt% Al2O3, representing a 496 % increase compared to pure EP and a 211 % increase compared to 3D-BN/EP composite materials. Furthermore, this composite material demonstrated excellent thermal stability and mechanical properties. This work provides a new direction for designing novel polymer-based composite materials with low filler loading and high thermal conductivity performance.

Enhanced thermal conductivity of epoxy resin by incorporating three-dimensional boron nitride thermally conductive network.

Packaging insulation materials with high thermal conductivity and excellent dielectric properties are favorable to meet the high demand and rapid development of third generation power semiconductors. In this study, we propose to improve the thermal conductivity of epoxy resin (EP) by incorporating a three-dimensional boron nitride thermally conductive network. Detailedly, polyurethane foam (PU) was used as a supporter, and boron nitride nanosheets (BNNSs) were loaded onto the PU supporter through chemical bonding (BNNS@PU). After immersing BNNS@PU into the EP resin, EP-based thermally conductive composites were prepared by vacuum-assisted impregnation. Fourier transform infrared spectrometer and scanning electron microscope were used to characterize the chemical bonding and morphological structure of BNNS@PU, respectively. The content of BNNS in BNNS@PU/EP composites was quantitatively analyzed by TGA. The results show that the thermal conductivity of the BNNS@PU/EP composites reaches 0.521 W/m K with an enhancement rate η of 30.89 at an ultra-low BNNS filler content (5.93 wt. %). Additionally, the BNNS@PU/EP composites have excellent dielectric properties with the frequency range from 101 to 106Hz. This paper provides an interesting idea for developing high thermal conductivity insulating materials used for power semiconductor packaging.

The Synthesis of Three-Dimensional Hexagonal Boron Nitride as the Reinforcing Phase of Polymer-Based Electrolyte for All-Solid-State Li Metal Batteries.

Powdery hexagonal boron nitride (h-BN), as an important material for electrochemical energy storage, has been typically synthesized in bulk and one/two-dimensional (1/2D) nanostructured morphologies. However, until now, no method has been developed to synthesize powdery three-dimensional (3D) h-BN. This work introduces a novel NaCl-glucose-assisted strategy to synthesize micron-sized 3D h-BN with a honeycomb-like structure and its proposed formation mechanism. We propose that NaCl acts as the template of 3D structure and promotes the nitridation reaction by adsorbing NH3 . Glucose facilitates the homogeneous coating of boric acid onto the NaCl surface via functionalizing the NaCl surface. During the nitridation reaction, boron oxides (BO4 and BO3 ) form from a dehydration reaction of boric acid, which is then reduced to O2 -B-N and O-B-N2 intermediates before finally being reduced to BN3 by NH3 . When incorporated into polyethylene oxide-based electrolytes for Li metal batteries, 5 wt % of 3D h-BN significantly enhances ionic conductivity and mechanical strength. Consequently, this composite electrolyte demonstrates superior electrochemical stability. It delivers 300 h of stable cycles in the Li//Li cell at 0.1 mA cm-2 and retains 89 % of discharge capacity (138.9 mAh g-1 ) after 100 cycles at 1 C in the LFP//Li full cell.

High thermal conductivity in three-dimensional BN/epoxy composites by engineered favorable interfacial adhesion between BN sheets

Because of their excellent insulation performance and processing properties, polymers are widely used in electrical and electronic applications. However, their further applications are severely constrained by their extremely low intrinsic thermal conductivity. Boron nitride (BN), which has high thermal conductivity and ideal insulation properties, is commonly used as a filler for improving the thermal conductivity of polymers. However, the high chemical inertia of the surface of BN makes it difficult to achieve an interconnection of BN sheets when building a three-dimensional (3D) BN skeleton in a polymer. In this study, urea melt pore preparation (UMPP) was used to fabricate a 3D BN skeleton. Urea was infiltrated into the BN skeleton to minimize the interfacial thermal resistance among the BN flakes and to join BNs. When the volume of a BN is 10 %, the thermal conductivity of the BN/epoxy composites is 3.15 W/(m·K). When the BN volume is 80 %, the thermal conductivity of BN/epoxy can reach 13.65 W/(m·K), which is 6500 % of pure epoxy resin. Additionally, the skeleton exhibits a remarkable mechanical strength capable of supporting weights up to 50,000 times its own, which facilitates easier handling and operation. The electrical resistivity volume of the UMPP composite is as high as that of the pure epoxy, whereas the dielectric loss is lower than that of pure epoxy. This study provides a new method for reducing internal interface thermal resistance of a skeleton formed by thermal conductive fillers with high chemical inertia such as boron nitride.

High thermal conductive polyurethane composite films with a three-dimensional boron nitride network in-situ constructed by multi-folding and multi-laminating

Based on the chemical modifications of the few-layer boron nitride nanosheets (BNNSs) prepared by ball milling, several BNNS/polyurethane (PU) composite films (non-laminated films) were prepared by solution blending. It showed that the modified BNNSs (M-BNNSs) in PU matrices assembled into boron nitride (BN) micro-flakes and mildly orientated along the film planes. Then, an approach of multi-folding and multi-laminating further promoted the orientation, stacking and connection of BN micro-flakes, by which a three-dimensional (3D) BN network composed of lamellar BN skeleton and a small number of BN linkers was in-situ constructed in the PU composite films (laminated films). For the existence of a continuous heat conductive channel based on the 3D BN network, the thermal conductivities (TCs) of the laminated films were obviously enhanced compared to the corresponding non-laminated films. The incorporation of M-BNNSs further improved the electrical insulation of the laminated films. When the M-BNNS content was 50 wt%, the in-plane TC of the laminated film reached 23.80 W/m·K. The laminated film with M-BNNS content of 30 wt% showed high TC, good flexibility, and outstanding electrical insulation, who is a promising candidate for the flexible thermal management materials.

Construction of three-dimensional interconnected boron nitride/sliver networks within epoxy composites for enhanced thermal conductivity

With the advent of the 5G era, the conspicuous increases in operating power and thermogenic capacity of integrated electronic components necessitated the development of enhanced thermal conductive polymeric composites with excellent heat dissipation properties. Herein, the polydopamine (PDA) and silver (Ag) modified BN (BN-PDA-Ag) was synthesized and a three-dimensional (3D) interconnected BN-PDA-Ag porous network was successfully fabricated by the salt template-assisted method to improve the thermal conductivity property of epoxy based composites. The high thermal conductive epoxy resin composites (3D BN-PDA-Ag/EP) were obtained by infiltrating epoxy into the 3D BN-PDA-Ag porous network. On one hand, the 3D BN-PDA-Ag porous skeleton provided continuous transfer paths for phonons, which was conducive to reducing phonon scattering. On the other hand, the Ag nanoparticles loaded on the BN surface bridged the adjacent BN sheets, significantly decreasing the thermal contact resistance between adjacent fillers. The isotropic thermal conductivity (TC) of 3D BN-PDA-Ag/EP composite with a BN-PDA-Ag content of 20.3 wt% reached 1.37 W/(m·K), which exhibited a evident enhancement of 661% compared with pure epoxy. The thermal management simulation and application results showed the composite had enormous application potential for electronic devices and components in heat dissipation.

Improved thermal conductivity of epoxy composites filled with three-dimensional boron nitride ceramics-carbon hybrids

Epoxy (EP) is the preferred packaging materials used as a crucial component in power semiconductor devices. However, its low thermal conductivity (TC) always has negative impact in the heat dissipation of electronic devices. In this paper, we use hole-making method to prepare three-dimensional boron nitride ceramics-carbon (3D-BN-C) hybrids which are filled in EP matrix to improve the TC of the 3D-BN-C/EP composites. The results show that TC values of 3D-BN-C/EP composites are much superior to the BN/EP composite with random distribution of BN and 3D-BN/EP composite without carbon. The improved TC is mainly attributed to the high TC-3D skeleton structure and the low interface thermal resistance (R) due to the carbon connected with BN fillers. Infrared thermal images and Comsol simulation demonstrate that high TC 3D-BN-C/EP composite offers excellent heat dissipation capability of EP composites used as packing insulation materials. In addition, the dielectric loss of 3D-BN-C/EP composite still remains at a relative low level in a wide frequency range, exhibiting good insulation property and great potential to be used as high-performance packing insulation materials in electronic device applications.

Frustrated Lewis pairs-engineered boron-doped 3D carbon nitride for improved electrocatalytic nitrogen reduction

It is of great importance to explore metal-free electrocatalysts with high electrocatalytic nitrogen reduction reaction (NRR) activity for ammonia (NH3) production. This work for the first time reports a three-dimensional (3D) boron (B) doped carbon nitride with frustrated Lewis pairs and deficiencies for efficient NRR via a facile copolymerization of sodium borohydride and urea precursors. The texture and the amount of B dopants in the resultant 3D carbon nitride can be finely tuned by varying the dosage of sodium borohydride. With the optimal B-doping content, the formed honeycomb-like 3D catalyst has a high NH3 yield rate of 17.8 μg h−1 mg−1 and Faradaic efficiency of 9.85% in 0.1 M Na2SO4 and 0.05 M H2SO4 electrolyte at −1.4 V vs RHE, which is considerably better than the undoped 3D carbon nitride. Comprehensive characterizations reveal that for the B-doped 3D carbon nitride, the unique 3D structure makes more introduced cyano groups and exposed nitrogen defects, favoring the contact between the electrolyte and the active sites. The abundant unsaturated B and N atoms function as frustrated Lewis pairs to strengthen N2 chemisorption and activation, lowing the barrier of NRR and meanwhile suppressing hydrogen evolution reaction. Moreover, in-situ UV–vis spectroscopy elucidates that the optimal potential at −1.4 V vs RHE benefits free electrons to participate in the NRR reaction because it matches the conduction potential of B-UCN-15. This study provides a new avenue for the rational design of nonmetal-based catalysts for NRR.

Superconducting boron allotrope featuring pentagonal bipyramid at ambient pressure.

Elemental boron has evoked substantial interest owing to its chemical complexity in nature. It can form multicenter bonds due to its electron deficiency, which induces the formation of various stable and metastable allotropes. The search for allotropes is attractive for finding functional materials with fascinating properties. Using first-principles calculations with evolutionary structure search, we have explored boron-rich K-B binary compounds under pressure. A series of dynamically stable structures (Pmm2 KB5, Pmma KB7, Immm KB9, and Pmmm KB10) containing boron framework with open channels are predicted, which can possibly be synthesized under high pressure and high temperature conditions. After the removal of K atoms, we obtain four novel boron allotropes, o-B14, o-B15, o-B36, and o-B10, which exhibit dynamical, thermal, and mechanical stability at ambient pressure. Among them, o-B14 contains an unusual B7 pentagonal bipyramid and appears in a bonding combination of seven-center-two-electron (7c-2e) B-B π bonds, which is the first time to be identified in three-dimensional boron allotropes. Interestingly, our calculation reveals that o-B14 can act as a superconductor with a Tc value of 29.1 K under ambient conditions.

Regulating the Electronic Structure of Cu-Nx Active Sites for Efficient and Durable Oxygen Reduction Catalysis to Improve Microbial Fuel Cell Performance.

The efficient and durable oxygen reduction reaction (ORR) catalyst is of great significance to boost power generation and pollutant degradation in microbial fuel cells (MFCs). Although transition metal-nitrogen-codoped carbon materials are an important class of ORR catalysts, copper-nitrogen-codoped carbon is not considered a suitable MFC cathode catalyst due to the insufficient performance and especially instability. Herein, we report a three-dimensional (3D) hierarchical porous copper, nitrogen, and boron codoped carbon (3DHP Cu-N/B-C) catalyst synthesized by the dual template method. The introduced B atom as an electron donor increases the electron density around the Cu-Nx active site, which significantly promotes the efficiency of the ORR process and stabilizes the active site by preventing demetallization. Thus, the 3DHP Cu-N/B-C catalyst exhibited excellent ORR performance with the half-wave potential of 0.83 V (vs reversible hydrogen electrode (RHE)) in a 0.1 M KOH electrolyte and 0.68 V (vs RHE) in a 50 mM PBS electrolyte. Meanwhile, 3DHP Cu-N/B-C had satisfactory stability with 94.16% current retention after 24 h of chronoamperometry test, which is better than that of 20% Pt/C. The MFCs using 3DHP Cu-N/B-C not only showed a maximum power density of up to 760.14 ± 19.03 mW m-2 but also operating durability of more than 50 days. Moreover, the 16S rDNA sequencing results presented that the 3DHP Cu-N/B-C catalyst had a positive effect on the microbial community of the MFC with more anaerobic electroactive bacteria in the anode biofilm and fewer aerobic bacteria in the cathode biofilm. This study provides a new approach for the development of Cu-based ORR electrocatalysts as well as guidance for the rational design of high-performance MFCs.

Activated Lone-Pair Electrons Lead to Low Lattice Thermal Conductivity: A Case Study of Boron Arsenide.

Reducing thermal conductivity (κ) is of great significance to lots of applications, such as thermal insulation, thermoelectrics, etc. In this study, we propose an effective approach for realizing low κ by introducing lone-pair electrons or making the lone-pair electrons stereochemically active through bond nanodesigning. By cutting at the (111) cross section of the three-dimensional cubic boron arsenide (c-BAs), the κ is lowered by more than 1 order of magnitude in the resultant two-dimensional graphene-like BAs (g-BAs). The underlying mechanism of activating lone-pair electrons is analyzed based on the comparative study on the thermal transport properties and electronic structures of g-BAs, c-BAs, graphene, and diamond (c-BAs → g-BAs vs diamond → graphene). The proposed approach for realizing low κ and the underlying mechanism uncovered in this study would largely benefit the design of advanced thermal functional materials, especially in future research involving novel materials for energy applications.

Three-dimensional network of hexagonal boron nitride filled with polydimethylsiloxane with high thermal conductivity and good insulating properties for thermal management applications

Electronic components tend to fail due to heat accumulation during use. As a result, thermally conductive and insulating polymer-matrix composites (PMCs) are in great demand in the electronics packaging industry. This study proposes a new hard-template approach for the construction of a three-dimensional hexagonal boron nitride foam (3D-BN) using PMMA microspheres as sacrificial materials. The 3D-BN is then filled with polydimethylsiloxane (PDMS) to create 3D-BN/PDMS composites with high thermally conductivities and good insulating properties. The results of various characterization analyses and 3D finite element simulation show that the 3D-BN is the fundamental factor in improving the thermal conductivity (TC) of the composites. Compared with nanoscale h-BN (nBN), micron h-BN (mBN) is more organized along the pore walls in 3D-BN, better utilizing the in-plane TC of h-BN while reducing the interface thermal resistance (ITR). The obtained lightweight composite exhibits a high TC of 1.868 Wm−1K−1 and an ultrahigh volume electrical resistivity of 3.66 × 1013 Ω m at 18.33 vol% mBN loading. This research provides a promising strategy for designing and fabricating thermal management PMCs.

Three-dimensional boron nitride network/polyvinyl alcohol composite hydrogel with solid-liquid interpenetrating heat conduction network for thermal management

• Solid-liquid interpenetrating heat conduction network. • Heat conduction and storage function. • Efficient thermal management materials. Polyvinyl alcohol hydrogels have been used in wearable devices due to their good flexibility and biocompatibility. However, due to the low thermal conductivity ( κ ) of pure hydrogel, its further application in high power devices is limited. To solve this problem, melamine sponge (MS) was used as the skeleton to wrap boron nitride nanosheets (BNNS) through repeated layering assembly, successfully preparing a three-dimensional (3D) boron nitride network (BNNS@MS), and PVA hydrogels were formed in the pores of the network. Due to the existence of the continuous phonon conduction network, the BNNS@MS/PVA exhibited an improved κ . When the content of BNNS is about 6 wt.%, κ of the hydrogel was increased to 1.12 W m −1 K −1 , about two times higher than that of pure hydrogel. The solid heat conduction network and liquid convection network cooperate to achieve good thermal management ability. Combined with its high specific heat capacity, the composites have an important application prospect in the field of wearable flexible electronic thermal management.

Cooling photoluminescent phosphors in laser-excited white lighting with three-dimensional boron nitride networks

Laser-excited white lighting, which is achieved by laser diodes and phosphor converters, has garnered increasing interest in recent years due to their high-power and high-brightness characteristics. Nevertheless, two long-standing thermal issues remain formidable: first, the photoluminescent phosphors also generate heat due to the Stokes loss, which are the second heat source in the packaging but long ignored; second, the phosphors are embedded in low-thermal-conductivity silicone and the generated heat is rather inefficient to dissipate. As a result, the accumulated heat leads to high temperature in phosphor particles and even thermal quenching, which deteriorate the luminescence, chromaticity, and reliability. In this work, these problems are successfully addressed by establishing three-dimensional (3D) boron nitride (BN) networks to cool the silicone-embedded phosphor particles in a facile and scalable method. When lighted under the driven current of 900 mA, the working temperature of phosphor layer is dramatically decreased by 95.2 °C with the 3D-BN network without sacrificing the luminescence and chromaticity. Such strategy with excellent cooling performance, high reliability, and easy scalability may hold great promise for broader optoelectronics applications beyond laser-excited white lighting.

Well-dispersive Pt nanocrystals anchored onto 3D boron and nitrogen double-doped reduced graphene oxide–carbon nanotube frameworks as efficient electrocatalysts for methanol oxidation

A bottom-up self-assembly method is developed to the fabrication of well-dispersive Pt nanocrystals anchored onto 3D B and N double-doped reduced graphene oxide-CNT frameworks, which express superior electrocatalytic performance for methanol oxidation. • 3D B and N double-doped graphene-CNT frameworks are fabricated via a co-assembly strategy; • The homogeneous distribution of Pt nanocrystals on the hybrid frameworks is realized; • The interconnected porous network and optimized electronic structure provide numerous active sites; • The as-derived catalysts express exceptional electrochemical performance toward methanol oxidation. The development of direct methanol fuel cell (DMFC) technology is an effective way to solve the problems of environmental pollution and energy shortage, while the scarcity of the highly-efficient anode catalysts with low cost severely limits its commercial use. In this work, we report a robust and convenient approach for the bottom-up construction of well-dispersive Pt nanocrystals anchored onto three-dimensional (3D) porous boron and nitrogen double-doped reduced graphene oxide–carbon nanotube frameworks (Pt/BNRGO-CNT) via a controllable co-assembly process. This architectural design can achieve a series of useful structural merits, such as 3D cross-linked porous network, large presence of B and N atoms, homogeneous Pt dispersibility, and high electrical conductivity. Consequently, the resulting Pt/BNRGO-CNT electrocatalysts exhibit excellent catalytic activity, strong anti-toxicity ability, and good long-term stability for methanol oxidation reaction, far exceeding those of Pt catalysts supported by the conventional undoped reduced graphene oxide, carbon nanotube, and carbon black matrixes.

Three-dimensional boron nitride reinforced thermal conductive composites with high elasticity

Polymer-based thermally conductive composites have good interfacial contact, processability and stability. However, because of the low thermal conductivity of polymer materials, usually, a larger percentage of filler is required to achieve high thermal conductivity, which leads to a drop in the resilience of the composite. To solve this problem, a melamine-formaldehyde resin sponge (MS) was used as a skeleton to wrap boron nitride nanosheets (BNNS) through repeated layering assembly, successfully preparing a three-dimensional (3D) boron nitride network (BNNS@MS). The mixture of poly(vinylidene fluoride) and BNNS (PVDF/BNNS) was formed in the pores of the 3D network of BNNS@MS. Due to the existence of the continuous phonon conduction network, the BNNS@MS/PVDF exhibits good thermal conductivity and high elastic deformation (rebound at 90% compression). When the content of BNNS is about 5 wt%, the thermal conductivity of the BNNS@MS/PVDF is increased to 1.43 ± 0.2 W/mK, 51.1% higher than that of PVDF/BNNS. The solid heat conduction network and polymer interplay to achieve good thermal management ability, and the composites have an important application prospect in the field of wearable flexible electronic thermal management.

High thermal conductivity of epoxy-based composites utilizing 3D porous boron nitride framework

With the rapid development of the third generation of wide bandgap semiconductor devices, there is an urgent need for highly thermally conductive and electrically insulating packaging materials to solve the heat dissipation problem in the microelectronic devices. In this work, the three-dimensional boron nitride (3D-BN) is successfully constructed by using a facile method, where the healthy and non-toxic food-grade material, curdlan, is used to provide a stable skeletons for growing 3D-BN using an aqueous foaming technique combined with a freeze-drying process. The thermally conductive network of 3D-BN is beneficial to improve the thermal conductivity of the epoxy resin (EP). The thermal conductivity of 1.63 W/(m·K) is obtained in the 3D-BN/EP composites at a BN content of 29.67 wt%, which is 9.1 times higher than that of pure EP. More importantly, the prepared composites also maintain excellent electrical insulation and dielectric properties, exhibiting a good potential to be used as the thermal interface material in the electronic devices.

Ice-templated graphene in-situ loaded boron nitride aerogels for polymer nanocomposites with high thermal management capability

Efficient heat dissipation is essential for further improving the integration of high-power electronic packaging equipment. Through-plane direction aligned three-dimensional boron nitride nanosheets/graphene(3D-BNNS/Gr) aerogels are designed as heat transferring skeletons for epoxy nanocomposites. Graphene was in-situ synthesized on BNNS by a combustion synthesis method to ensure good contact, and subsequent aligning of BNNS/Gr nanofillers by a self-assembly ice-templating strategy to reduce contact resistance between individual BNNS. At a relatively low 3D-BNNS/Gr loading of 11.2 vol%, the composites exhibit superior through-plane thermal conductivities of 2.23 and 1.09 W m−1 K−1, demonstrating a 1073% and 1069% thermal conductivity enhancement at room temperature (RT) and liquid nitrogen temperature (77 K) compared with pure epoxy resin. Meanwhile, the mechanical properties of the composites at RT and 77 K were synchronously enhanced. Furthermore, the 3D-BNNS/Gr-epoxy nanocomposite film then acts as a heat spreader for heat dissipation of high-power LED modules and exhibits superior cooling efficiency.