Interconnected Conductive Network Research Articles

Coaxial Hard Carbon‐coated Carbon Nanotubes as Anodes for Sodium‐ion Batteries

AbstractAlthough being advantageous, the sodium‐ion storage capability of hard carbon would be better if its electrical conductivity could be improved. Herein, 3D hard carbon‐coated carbon nanotubes (CNTs@C) with interconnected conductive networks are fabricated by inducing hard carbon uniformly growth on CNTs. Compared with the isolated hard carbon spheres, the interconnected wire shape of CNTs@C reduces the ion transfer distance and increases the conductivity of hard carbon. By optimizing the thickness of the hard carbon layer and annealing temperature, the optimized CNTs@C displays a reversible specific capacity of 275.9 mAh g−1 at 0.1 A g−1 as anode material for SIBs. Furthermore, the material shows remarkable rate capability (102.8 mAh g−1 at 5 A g−1) and long‐life cycling performance (∼100% capacity retention after 1000 cycles at 5 A g−1). The results of this study provide an effective route for designing novel carbon‐based composite materials as anodes for SIBs.

Selective laser sintering 3D-Printed conductive thermoplastic polyether-block-amide elastomer/carbon nanotube composites for strain sensing system and electro-induced shape memory

A novel mixed powders made up of laboratory-made thermoplastic polyether-block-amide (TPAE) and multiwalled carbon nanotubes (MWCNTs) for the selective laser sintering (SLS) 3D printing have been prepared through an environment-friendly approach and the carbon nanotube conductive network structure is established in the SLS-processed nanocomposite devices. The electrical properties, strain sensing property and electro-induced shape memory effect of flexible TPAE/MWCNTs nanocomposites are fully investigated. The conductivity of TPAE/MWCNTs nanocomposites increases as the MWCNTs content increases owing to the interconnected MWCNTs conductive network. During compressing test with different deformation strain and speed, the SLS-processed flexible sensor exhibits a regular, fast, sensitive and stable cyclic response which shows its great potential for artificial electronic skin, human-machine interface and health monitoring. The TPAE-5.0C nanocomposite also possessed an excellent shape recovery ability during electro-induced shape memory cycle which was triggered by Joule heat under DC voltage. The MWCNTs-TPAE powder prepared here provides a novel material for SLS 3D-printing and the SLS-processed devices with outstanding performance and multiple functions will be very useful for developing flexible and lightweight wearables in the future.

Ultrathin NiFe-LDH nanosheets strongly coupled with MOFs-derived hybrid carbon nanoflake arrays as a self-supporting bifunctional electrocatalyst for flexible solid Zn-air batteries

The construction of a hybrid hierarchical architecture is a promising strategy for optimizing the electrocatalytic activity and the performance of flexible Zn-air battery. However, it still remains a challenging task. This study reports on the use of a simple approach in the preparation of a flexible 3D self-supporting bifunctional catalyst. Ultrathin NiFe-based layered double hydroxide nanosheets (NiFe-LDH) have in this approach been strongly coupled to a metal-organic framework (MOF)-derived carbon nanoflake array, to be used in flexible Zn-air batteries. Importantly, the introduction of Co nanoparticles that were anchored onto the nitrogen-doped porous carbon (Co-NC) nanoflakes provided an abundance of active sites for the oxygen reduction reaction (ORR). Moreover, the catalytic oxygen evolution reaction (OER) process was improved by altering the local electronic structure of the Ni and Fe species in NiFe-LDH. The 3D interconnected conductive network structure, in addition to the strong coupling between NiFe-LDH and Co-NC, was found to give a catalyst with superior electrocatalytic OER performances. The overpotential was only 284 mV at 50 mA cm−2 in an alkaline medium, which is a result that outperforms the commercial RuO2 catalyst. This bifunctional catalyst did also exhibit a good catalytic performance that is comparable to that of commercial Pt/C towards ORR. Interestingly, when this catalyst was used as binder-free air cathode, the assembled flexible solid-state Zn-air battery demonstrated a favorable power density, cycling stability, and mechanical flexibility. The present work offers a facile and efficient strategy for the development and construction of self-supporting bifunctional OER/ORR electrocatalysts, to be used in wearable and flexible electronic devices.

Facile Synthesis of Amino-functionalized Mesoporous Fe3O4/rGO 3D Nanocomposite by Diamine compounds as Li-ion Battery Anodes

Being an essential part of lithium-ion batteries, the development of novel anode materials currently receives much attention. Among these, the high theoretical capacity of Fe3O4 (924 mAh g−1) makes it highly promising. However, massive volumetric changes and particle aggregation during repeated insertion/de-insertion of lithium ions damage the electrode structure and destroy the electrical connection with the current collectors, resulting in rapid and significant capacity losses. One strategy to overcome this problem is the employment of graphene-based compounds as a substrate in an interconnected porous conductive network using a crosslinker (e.g., ethylene diamine) to adjust the distance between the graphene layers. Such a 3D framework creates enough available space for the lithium ions to be inserted or de-inserted respectively to or from the electrode during the charge-discharge process. Moreover, this strategy prevents large electrode volume changes and the accumulation of Fe3O4 during cycling. Herein, an ex situ method was used to synthesize amino-functionalized mesoporous Fe3O4/graphene-based nanocomposites. In the first step, Fe3O4 nanoparticles were synthesized with the addition of ethylenediamine (EDA), whereby mesoporous Fe3O4 nanoparticles were obtained (Fe3O4-E). In the second step, Fe3O4-E/rGO nanocomposites were prepared with the help of electrostatic interactions. The Fe3O4-E/rGO nanocomposite showed good cycling performance vs. Li-metal and a high reversible capacity (∼465 mAh g−1) and average coulombic efficiency of ∼98% after 250 cycles at the current density of 1000 mA g−1. These promising results can be attributed to the presence of EDA in the formation of mesoporous nanoparticles and the 3D structure of the resulting composite. Itprevents the fragmentation of Fe3O4 particles induced by the formation of mesoporous structures and the restacking of rGO sheets generated by adjusting the layer spacing.

Multifunctional effects of hollow flower-like CoTiO3 microspheres wrapped by reduced graphene as sulfur host in Li-S battery

The poor conductivity of sulfur, the shuttle effect and sluggish redox reaction kinetics of lithium polysulfides (LiPSs) are considered the main obstacles to the practical application of Lithium-sulfur (Li-S) batteries. Thus, it is urgent to design multifunctional host materials to eliminate these obstacles. Herein, we designed a hollow flower-like CoTiO3 wrapped by reduced graphene oxide (h-CoTiO3@rGO) as sulfur host materials. The hollow structure of h-CoTiO3@rGO not only endows sufficient space for high sulfur loading, but also physically and chemically confines the shuttle effect of LiPSs through the formation of Co-S chemical bonding. The large specific surface area and excellent electrocatalytic ability of h-CoTiO3@rGO provide amounts of active sites to accelerate the redox reaction of LiPSs. Meanwhile, the conductive reduced graphene oxide (rGO) covered on the surface of CoTiO3 microspheres offers an interconnected conductive network to support the fast electron/ion transfer. Profit from these merits, the battery employing the multifunctional h-CoTiO3@rGO as sulfur host exhibited excellent cycling stability with an ultralow capacity fading of 0.0127 % per cycle after 500 cycles at 1C. Even the battery with high sulfur loading of 5.2 mg/cm2 still delivered a high area capacity of 5.02 mAh/cm2, which was competitive with the commercial Li-ion batteries. Therefore, the competitive capacity and superior cycling stability suggest that the h-CoTiO3@rGO/S cathode is a potential candidate for high-performance Li-S batteries.

Composite of Ge and α-MnSe in carbon nanofibers as a high- performance anode material for LIBs

Improving the performance of anode materials is of great importance for lithium-ion batteries (LIBs). Transition metal selenides compositing carbon and germanium (Ge) have attracted extensive attention. In this work, an anode material that integrates Ge and α-MnSe in carbon nanofibers (CNFs) was first synthesized by heat treatment after electrospinning. The coupling of Ge with α-MnSe and carbon can cause the growth process of α-MnSe to occur inside the CNFs, which can buffer the volume change, refine the grains and avoid particles protruding from the surface of CNFs. In addition, the interconnected conductive network of Ge/α-MnSe@CNFs can provide fast diffusion channels for Li ions and improve the electrical conductivity. Importantly, there is a synergistic effect of Ge, α-MnSe, and CNFs on the anode material for LIBs. As expected, Ge/α-MnSe@CNFs exhibited an excellent performance with a capacity of 1514.7 mAh g −1 after 200 cycles at 0.1 A g −1 and 1030 mAh g −1 after 1000 cycles even at 1 A g −1 . Therefore, this new preparation strategy of Ge/α-MnSe@CNFs offers novel ideas to develop high-performance and long-life LIBs. • Ge/α-MnSe carbon nanofibers were first synthesized for lithium-ion batteries. • Coupling Ge with α-MnSe can help to limit the in-situ growth of α-MnSe inside CNFs rather than at the surface. • Ge/α-MnSe@CNFs showed a high capacity and long-time cycles life for LIBs.

Electrochemical sensing platform based on graphitized and carboxylated multi-walled carbon nanotubes decorated with cerium oxide nanoparticles for sensitive detection of methyl parathion

We proposed a low-cost ultrasonic-assisted strategy to prepare the graphitized and carboxylated carbon nanotubes (GR-MWCNTs-COOH) and cerium oxide (CeO2) nanoparticles nanocomposite, which was applied to fabricate the GR-MWCNTs-COOH@CeO2/GCE sensor for the electrochemical detection of methyl parathion (MP). GR-MWCNTs-COOH with graphitization and carboxylation showed excellent conductivity property, large surface area, and gratifying hydrophilicity. Graphitization enhanced the electrical conductivity of MWCNTs, and carboxylation promoted the homogeneous dispersion of MWCNTs. The double-functionalization of MWCNTs helped form the interconnected carbon nanotubes conductive network. CeO2 nanoparticles with good catalytic ability possessed high enrichment capability of MP because of the good affinity between CeO2 and phosphate groups. Moreover, the double-functionalized GR-MWCNTs-COOH not only promoted the uniform dispersion of CeO2 nanoparticles but also compensated for the poor electrical conductivity of CeO2 nanoparticles. The GR-MWCNTs-COOH@CeO2/GCE sensor presented a low detection of limit of 0.0285 μM (MP concentration range: 0.01–10 μM). The satisfactory reproducibility, repeatability, and anti-interference were obtained at the fabricated nanohybrid sensor. When applied for the MP determination in spinach and cabbage samples, the low RSD values of 1.71–4.25% and satisfactory recoveries of 95.8–100.7% could be achieved at the GR-MWCNTs-COOH@CeO2/GCE sensor. This work provided an important reference for the design of high-performance MP sensor.

Constructing a BNNS/aramid nanofiber composite paper via thiol-ene click chemistry for improved thermal conductivity

Benefiting from its superior insulation and outstanding environmental adaptability, aramid nanofibers (ANFs) composite paper has attracted tremendous attention in the flexible electronics and electronic packaging field. However, the extremely low thermal conductivity of aramid nanofiber paper faced a serious challenge under the rapidly increasing heat dissipation demand. Herein, boron nitride nanosheets (BNNS) were introduced to ANFs paper via a controllable vacuum-assisted filtration, and hydrogen bonding and light-induced “thiol-ene” click chemistry were proposed to improve the interfacial combination. Specifically, BNNS was prepared via the microwave-assisted hydrothermal method with subsequent sulfhydryl functionalization (f-BNNS) and s-ANFs (grafted ANFs) were prepared by deprotonation of chopped aramid fibers and then treated with KH570 coupling agent. The results showed that the through-plane thermal conductivity (TC) of f-BNNS/s-ANFs composite paper reached 0.224 W/m K with 50 wt% f-BNNS loading, exhibiting an increase of 540% and 184%, respectively, compared with pure ANFs paper and BNNS/ANFs paper. The abundant hydrogen bonding and covalent bonding via “thiol-ene” click chemistry between f-BNNS and s-ANFs contributed to enhanced interface and interlayer bonding, and the continuous interconnected thermal conductive network constructed by f-BNNS was conducive to improving TC. Meanwhile, the composite paper held excellent mechanical properties and reliable electrical insulation.

Ultrasensitive determination of diquat using a novel nanohybrid sensor based on Super-P nanoparticles dispersed palygorskite nanofibers

The excessive diquat (DQ) residue poses a serious hazard to the ecological environment and human health. Herein, a simple, low-cost, and scalable ultrasonication-assisted strategy was proposed to fabricate the composite of Super-P carbon black nanoparticles dispersed palygorskite (Pal) nanofiber, which was employed to construct an electrochemical sensor for DQ determination. The Pal/Super-P/GCE sensor exhibited ultrasensitive determination performance with a low detection limit (0.1514 nM) and high sensitivity (44.141 μA μM−1) in the linear DQ concentration range of 0.00050–1.0 μM. The recoveries of the constructed sensor ranged from 95.6 % to 100.3 % when applied to detect DQ in river water, potato, and cucumber. The above enhanced DQ detection performance was primarily due to the synergistic effect of Pal and Super-P. Pal with high adsorption ability and excellent biocompatibility could provide numerous attachment sites for DQ adsorption due to the superior ion-exchange property and plentiful Si-OH on its surface. Super-P with pearl-chain like structure contributed to forming an interconnected conductive network, thus facilitating the homogeneous dispersion of Pal and compensated for the poor conductivity of Pal. This study provides a valuable reference in developing clay-based nanocomposite via ultrasonication-assisted strategy to achieve the application of electrochemical sensor at the ultra-trace levels detection of pesticides.

Improved electromagnetic interference shielding properties of poly (vinylidene fluoride) composites based on carbon nanotubes and graphene nanoplatelets

AbstractIn order to improve the electromagnetic interference (EMI) shielding performance of poly(vinylidene fluoride) (PVDF), both carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) as functional fillers were chosen and employed in this work. The PVDF‐based composites were prepared through melt blending and the hybrid fillers exhibited fine interaction with PVDF matrix. CNTs and GNPs could act as heterogeneous nucleation agents for PVDF matrix, thus increased the crystallization peak temperature. The gradual formation of interconnected conductive network of hybrid fillers could improve the conductivity and rheological properties of PVDF effectively. Especially, in contrast to those of pure PVDF, about four orders of magnitude increment for their storage modulus and complex viscosity of PVDF/GNPs/CNTs composite as well as approximate 10 orders of magnitude improvement in their electrical conductivity were obtained. Adding 2 wt% CNTs in PVDF matrix could generate the conductive network and further GNPs addition was helpful to obtain higher EMI shielding effectiveness. The new PVDF samples would possess wide applications as electromagnetic shielding materials, on account of their simple processing, low‐cost and without use of organic solvent characteristics.

An interconnected and scalable hollow Si-C nanospheres/graphite composite for high-performance lithium-ion batteries

Silicon (Si) anode is the most promising alternative for next generation lithium-ion batteries (LIBs) owing to large theoretical capacity, low working voltage and abundant natural resources. However, tremendous volume change of Si during the (de)lithiation processes causes repetitive formation of solid electrolyte interphase (SEI) layers, loss of electrical contact and electrodes pulverization, limiting its commercial application. Herein, we fabricate an interconnected hollow Si-C nanospheres/graphite composite via a facile and scalable approach. Notably, hollow Si-C nanospheres and graphite are homogeneously combined by using the surfactants as surface modifiers of graphite and introducing carbon dioxide (CO2) into magnesiothermic reduction reaction, resulting in the enhanced compatibility between hollow Si-C nanospheres and graphite, and the well-established electrical conductive network. The resultant Si-C nanospheres/graphite composite anode with carbon content of 59 wt% delivers a large reversible specific capacity of 662 mAh g−1 and a high capacity retention of 65.7% at 0.5 A g−1 after 200 cycles. Such excellent rate performance and superior cycling performance are attributed to high electrical conductivity and buffering effect of graphite, superior compatibility between hollow Si-C spheres and graphite, uniform distribution of both Si-C nanospheres with a unique hollow architecture and graphite flakes inside the composites and well-established interconnected electrical conductive carbon networks, which can effectively alleviate Si volume expansion and maintain good electrical contact during cycling. This strategy provides insights into designing Si-based anodes for practical LIBs.

In Situ Fabrication of Porous Cox P Hierarchical Nanostructures on Carbon Fiber Cloth with Exceptional Performance for Sodium Storage.

Superior high-rate performance and ultralong cycling life have been constantly pursued for rechargeable sodium-ion batteries (SIBs). In this work, a facile strategy is employed to successfully synthesize porous Cox P hierarchical nanostructures supported on a flexible carbon fiber cloth (Cox P@CFC), constructing a robust architecture of ordered nanoarrays. Via such a unique design, porous and bare structures can thoroughly expose the electroactive surfaces to the electrolyte, which is favorable for ultrafast sodium-ion storage. In addition, the CFC provides an interconnected 3D conductive network to ensure firm electrical connection of the electrode materials. Besides the inherent flexibility of the CFC, the integration of the hierarchical structures of Cox P with the CFC, as well as the strong synergistic effect between them, effectively help to buffer the mechanical stress caused by repeated sodiation/desodiation, thereby guaranteeing the structural integrity of the overall electrode. Consequently, Cox P@CFC as an anode shows a record-high capacity of 279mAhg-1 at 5.0Ag-1 with almost no capacity attenuation after 9000 cycles.

Integrated coaxial graphene-based yarn with multidimensional architecture for self-powered photoelectrochemical methane sensor

Effective and reliable methane detection is essential and critical to environment protection, and life and property safety. However, how to enable a sensing platform for methane monitoring with high sensitivity and stability, and meanwhile with excellent structural flexibility and ease of integration remains a significant challenge. Herein, an integrated coaxial yarn-shaped self-powered photoelectrochemical methane sensor was successfully designed and constructed by employing wet-spun graphene (G) fiber as the inner electrode, G-based mixed-dimensional materials hybridization as the outer electrode, and a polymer gel coated in-between as the electrolyte separator. The high surface roughness and significant transmittance of obtained device enabled effective adsorption capacity and essential light penetration. A continuous and thin gel electrolyte interlayer in the sensor and single-walled carbon nanotube (SWNT)-bridged interconnected conductive network in a multidimensional hybrid facilitated fast ion/electron transport. Ascribed to above structural merits, the resulting sensor delivered a wide linear range from 0.05% to 0.47% and a low detection limit of 0.02%, while maintaining rapid response (0.3 s), outstanding selectivity and perfect working performance during bending. This work provides useful guidelines for designing and fabricating photoelectrochemical sensors toward highly sensitive gas detection.

Lamellar network structure constructed by ZnSe/C nanorods for high-performance potassium storage

The rapid development of promising potassium-ion batteries (PIBs) is still greatly hindered by typical constraints, including sluggish diffusion kinetics and structural degradation caused by severe volume vibration during the intercalation/deintercalation of K+. To eliminate such issues, herein we designed a novel lamellar network structure constructed by carbon-coated ZnSe/C nanorods (LN-ZnSe/C) as the anode of PIBs. The LN-ZnSe/C composite was synthesized via glucose-assisted freeze-drying and subsequent in-situ selenization of the zinc tartrate precursor. Kinetics analysis revealed that the nanosize and lamellar network structure of ZnSe/C enabled fast K-ion diffusion. Meanwhile, the carbon layer, as the binder and structure reinforcer of the ZnSe nanorods, provided a stable interconnected conductive network and enhanced the mechanical integrity of ZnSe for volume variation. Benefitting from these merits, LN-ZnSe/C revealed high reversible capacity (383 mA h g−1 at a current density of 200 mA g−1 after 100 cycles), superior rate capacity (230 mA h g−1 at 5 A g−1), and long cycling life (179 mA h g−1 after 1200 cycles at 1 A g−1). This work demonstrates a new promising development framework for fabricating network structures with a 3D charge-transport system to advance potassium-based energy storage devices.

Sensitivity enhanced, highly stretchable, and mechanically robust strain sensors based on reduced graphene oxide-aramid nanofibers hybrid fillers

Recently, high-performance flexible strain sensors with remarkable sensing performance and desired mechanical properties have attracted great attention in the field of wearable electronic devices. However, it is still challenging to realize the tuning of sensitivity and sensing range in graphene-based strain sensors. Herein, a sensitivity enhanced, highly stretchable, and mechanically robust strain sensor is proposed based on reduced graphene oxide (RGO)-aramid nanofibers (ANFs) hybrid fillers and natural rubber (NR) matrix. Due to the strong π-π interactions, the RGO-ANFs hybrid fillers were constructed and orderly assembled around the NR particles, resulting in the formation of a unique interconnected conductive network. The resultant RGO-ANFs/NR strain sensors exhibited significantly improved sensitivity (gauge factor up to 870), wide detection range (0 ∼ 226%), expected mechanical properties (tensile strength >6 MPa), excellent stability, repeatability, and durability (1000 cycles), as well as fast feedback (response time of 195 ms). The strain sensor could monitor joint movements and physiological activities in real time at a wide temperature range (-20 ℃ ∼ 60 ℃), demonstrating the prospect as a flexible wearable device that could be applied under various temperature conditions.

Emcoating Architecture Construction via CO2 /H2 Coupling Treatment Doubles Reversible Capacity of NbO2 /C Anode.

As a promising alternative as lithium-ion anode, niobium dioxide appeals to researchers due to high theoretical capacity and good electron conductivity. However, rarely work about NbO2 based high performance anode is reported. Here, NbO2 nanoparticles emcoated in continuous carbon matrix is constructed through CO2 /H2 coupling treatment. CO2 activation introduces unique carbon emcoating structure, which builds interconnected electron conductive network with low carbon content. Furthermore, crystallographic phase of NbO2 is enhanced during H2 treatment, which increases the lithium storage ability. Electrochemical performance of NbO2 anodes is significantly improved based on the carbon emcoating structure. A high reversible capacity of 391 mAh g-1 is retained after 350 cycles at 0.2 C. Additionally, at a current density of 1 A g-1 , the reversible capacity reaches 139 mAh g-1 . Compared with conventional NbO2 /C nanohybrids, the lithium diffusion coefficient of carbon-emcoated sample shows improvement of three orders of magnitude. Moreover, the in situ XRD investigation shows a reversible lithium insertion behaviour with a limited volume change.

Constructing hierarchical structure via in situ growth of CNT in SiO2-coated carbon foam for high-performance EMI shielding application

Carbonated melamine foam (CMF) with a three-dimensional (3D) inner connected network is considered as one of the promising candidates to fabricate electromagnetic interference (EMI) shielding materials. To further improve EMI shielding performance, CMF based hybrids with three-dimensional structure by the combination of SiO2 and in-situ growth carbon nanotubes (CNT) have been synthesized for preparing polydimethylsiloxane (PDMS) composite: CMF@SiO2-CNT/PDMS. Owing to the structural match between the length of CNT and the diameter of holes in the CMF@SiO2, the relatively high electrical conductivity of 50.43 S/m has been achieved in the composite with the thickness of 2 mm, which assures an excellent EMI shielding effectiveness (SET = 61.34 dB) in the frequency range from 8.2 to 12.4 GHz. Meanwhile, a high absorption effectiveness (SEA = 53.65 dB) of the composite infers an absorption dominant performance of the composite because of the unique porous structure and inter-connected conductive network, which helps to avoid secondary EMI pollution. We hope this work can provide a new route for fabricating EMI shielding materials with high performance.

Nanoporous nickel with rich adsorbed oxygen for efficient alkaline hydrogen evolution electrocatalysis

Sluggish water dissociation kinetics severely limits the rate of alkaline electrocatalytic hydrogen evolution reaction (HER). Therefore, finding highly active electrocatalysts and clarifying the mechanism of water dissociation are challenging but important. In this study, we report an integrated nanoporous nickel (np-Ni) catalyst with high alkaline HER performance and the origin of the corresponding enhanced catalytic activity. In 1 mol L−1 KOH solution, this np-Ni electrode shows an HER overpotential of 20 mV at 10 mA cm−2, along with fast water dissociation kinetics. The excellent performance is not only attributed to the large surface area provided by the three-dimensional interconnected conductive network but also from the enhanced intrinsic activity induced by the unique surface properties. Further studies reveal that the types of oxygen species that naturally form on the Ni surface play a key role in water dissociation. Remarkably, when the lattice oxygen almost disappears, the Ni surface terminates with adsorbed oxygen (Oads), exhibiting the fastest water dissociation kinetics. Density functional theory calculation suggests that when Oads acts as the surface termination of Ni metal, the orientation and configuration of polar water molecules are strongly affected by Oads. Finally, the H—OH bond of interfacial water molecules is effectively activated in a manner similar to hydrogen bonding. This work not only identifies a high-performance and low-cost electrocatalyst but also provides new insights into the chemical processes underlying water dissociation, thus benefiting the rational design of electrocatalysts.

Aligning diamond particles inside BN honeycomb for significantly improving thermal conductivity of epoxy composite

Construction of interconnected heat conductive network in polymer is essential to effectively transport heat in thermal management materials. Due to synergistic effect, hybrid fillers are increasingly utilized in composites for higher thermal conductivity, but how to achieve better enhancement is still an open problem. In this paper, a pod-like 3D interconnected heat percolation network was obtained by aligning diamond inside boron nitride (BN) honeycomb. The BN honeycomb used as secondary templets was prepared by ice template method. Subsequently, the epoxy (EP) and diamonds were filled into it simultaneously by vacuum infiltration. SEM and computed tomography results demonstrated that highly ordered thermal conductive channels have been constructed. When the content of BN is 7 vol% and diamond is 12 vol%, the thermal conductivity of the composite is as high as 2.720 W/(m·K), which is 12.5 and 5.8 times higher than that of pure EP and randomly mixed sample, respectively. To better understand the enhance mechanism, through the parallel structural model calculations, the effective thermal conductivity of the local tightly packed diamond part was increased from 1.210 W/(m·K) to 11.318 W/(m·K) in the composite. The findings suggested that the bridging effect of BN wall on connecting diamond particles also contributed to enhanced property of the composite. This study offers a novel strategy for obtaining higher thermal conductivity with low filler loading in hybrid composites.

Facile premixed flame synthesis C@Fe2O3/SWCNT as superior free-standing anode for lithium-ion batteries

Premixed flame configuration is considered as an effective method for the synthesis of carbon materials. In this work, flexible single-walled carbon nanotube network decorated by carbon-encapsulated Fe2O3 nanoparticles (C@Fe2O3/SWCNT) membrane was in-situ fabricated via a facile floating catalyst premixed ethanol flame method, and followed by annealing treatment. In this process, low-cost ethanol and ferrocene were used as carbon source and catalyst precursor for the synthesis of C@Fe2O3/SWCNT, respectively. Benefiting from the interconnected conductive network, the as-fabricated C@Fe2O3/SWCNT membrane was used as a free-standing anode for lithium-ion batteries. Structural characterization revealed that the ultrafine Fe2O3 nanoparticles homogeneously anchored on the SWCNT network, which facilitates the fast diffusion for electron. Furthermore, the carbon layers uniformly enwrap on Fe2O3 can effectively suppress the aggregation and buffer the volume change of Fe2O3 during the lithiation/delithiation process. Consequently, this material delivered an excellent lithium storage performance with a high reversible capacity of 1294.7 mAh g−1 at 50 mA g−1, and an excellent cyclability of 82.5% retention is obtained after cycles at 2 A g−1. This study provides a novel low-cost and fast method for preparing flexible advanced electrode for next-generation rechargeable batteries.