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All‐solid‐state batteries with conversion‐type cathodes promise to exceed the performance of lithium‐ion batteries due to their high theoretical specific energy and potential safety. However, the reported performance of solid‐state batteries is still unsatisfactory due to poor electronic and ionic conduction in the composite cathodes. Here, in situ formation of active material as well as highly effective ion‐ and electron‐conducting paths via electrochemical decomposition of Li6PS5Cl0.5Br0.5 (LPSCB)/multiwalled carbon nanotube mixtures during cycling is reported. Effectively, the LPSCB electrolyte forms a multiphase conversion‐type cathode by partial decomposition during the first discharge. Comprehensive characterization, especially operando pressure monitoring, reveals a co‐redox process of two redox‐active elements during cycling. The monolithic LPSCB‐based cell shows stable cycling over 1000 cycles with a very high capacity retention of 94% at high current density (0.885 mA cm−2, ≈0.7 C) at room temperature and a high areal capacity of 12.56 mAh cm−2 is achieved. [ABSTRACT FROM AUTHOR]

Efficient thermal dissipation is one of the most critical factors constraining the development of modern microelectronic devices. Placing vertically aligned carbon nanotubes (VACNTs) with anisotropic thermal conductive between high-power devices and heat sink such as copper plate can improve the interfacial thermal conductance. Due to the limited contact area between CNTs and the surface of the devices, direct use of ACNTs as thermal interface material fails to meet people's expectations. Here, we employ reduced graphene oxide (rGO) as the substrate for the growth of CNT arrays. VACNTs grown on rGO (rGO-ACNT) by chemical vapor deposition are then used as thermal conducting filler in epoxy resin. Compared with direct contact between CNT and the interface, using CNT and reduced graphene oxide junction to form contact with the surface can improve heat transfer efficiency. The resultant composite film exhibited excellent thermal conductivity at 9.62 W m−1 K−1 along the thickness direction. The obtained rGO-ACNT and its composite present higher thermal conductivity and heat transfer ability than ACNT. This strategy offers an insight into the easy preparation of flexible and highly thermal conductive composite materials, which may enable potential applications in advanced electronic devices. [ABSTRACT FROM AUTHOR]

A novel hierarchical porous carbon–carbon nanotube hybrid (HPCC) is prepared using a one-step strategy that uses nickel nanoparticles as the template for pore formation and at the same time, as the catalyst for carbon nanotube (CNT) growth. Such a structure can not only store sulfur in the micro- and mesopores, which restrict the shuttling of polysulfides, but also ensure good electrical conductivity of the whole system due to the incorporation of CNTs. The hierarchical porous structure also ensures fast mass transportation. These factors effectively guarantee the high electrochemical performance of sulfur stored in this carbon in lithium–sulfur batteries. [ABSTRACT FROM AUTHOR]

The rod-like manganese dioxide (MnO2)/acid-treated carbon nanotube (a-CNT) nanocomposites have been synthesized by a simple co-precipitation method. The MnO2 nanorod with the diameter of about 10nm and length of 50∼120nm is in-situ deposited on the surface of acid-treated CNT through the redox reaction of KMnO4 and Mn(CH3COO)2·4H2O. Results show that the electron transfer efficiency of the MnO2/a-CNT nanocomposites is greatly enhanced and results in a high electrical conductivity. The energy storage mechanism of as-prepared MnO2/a-CNT in mild aqueous electrolyte (ZnSO4 and MnSO4) is associated with the insertion/extraction of zinc ion into/from the tunnels of crystalline α-MnO2. The composites display both excellent storage properties with zinc ions (∼400 mAh·g−1 at 1 A·g−1) and reversibility at various current rates (∼100% coulombic efficiency after 500 charge/discharge cycles). The MnO2/a-CNT nanocomposites are rather promising cathode material for high performance rechargeable zinc ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: Different amounts of multi-walled carbon nanotubes (MWCNTs) are added to anode catalyst layer in the membrane electrode assemblies (MEAs) of direct methanol fuel cells (DMFCs). The MEA with 0.5wt.% carbon nanotubes (CNTs) shows the best performance in DMFC. In the protonic conductivity tests, a 0.5 wt.% amount of MWCNTs results in the highest protonic conductivity. SEM and TEM observations show that a continuous and uniform distribution of Nafion ionomer layer is formed on the MWCNT surface. Therefore, the dispersed MWCNTs in the catalyst layer are considered to be helpful for developing the pathways of protons transport. [Copyright &y& Elsevier]

Flexible strain sensors have enormous application demands in health monitoring, soft robotics, and artificial skin. Traditional flexible strain sensors mainly focus on identifying strain amplitude. However, to determine complex movements, it is necessary for sensors to recognize not only the amplitude but also the direction of strain. Here, we propose a multi-directional strain sensor constructed from three flexible strain sensor units, which are based on a carbon nanotube (CNT) array, and configured in a right-angled triangle arrangement. Each strain sensor unit exhibited a strain detection range of over 90%, durability of over 5000 cycles, and fast response time (<150 ms). The multi-directional strain sensor can accurately identify the amplitude and direction (up to 180°) of the strain simultaneously. By optimizing the height and the size of the CNT array strips within the strain sensor unit, the preferred parameters for the sensor unit were determined. Further, by incorporating a neural network algorithm, the multi-directional strain sensor achieved synchronous detection of strain amplitude and direction with an accuracy rate exceeding 98%. Therefore, this work provides a new strategy for the design and construction of multi-directional strain sensors, underscoring their broad application potential in the fields of human motion monitoring and gesture recognition. [Display omitted] [ABSTRACT FROM AUTHOR]

Silicon-embedded porous carbon microspheres with an exceptional conductive framework for ions and electrons were obtained by electrospraying a mixed polymer solution of polystyrene and polyvinylpyrrolidone, containing silicon nanoparticles, carbon nanotubes and carbon blacks, and subsequent heat treatment. In the composite microspheres, silicon particles were embedded in the porous carbon framework composed of interwoven carbon nanotubes, filled carbon blacks and interconnected amorphous carbon derived from polymers. The cage-like porous carbon microspheres could not only accommodate the volume expansion of silicon but also ensure a robust electrical contact, fast transport for electrons and ions. Therefore, the silicon/carbon anode exhibits a high capacity of 1325 mAh g −1 at 0.2 A g −1 after 60 cycles and superior rate capability with a capacity of 925 mAh g −1 at a large current density of 5 A g −1 . [ABSTRACT FROM AUTHOR]

Multicomponent composites with an atomic-scale distribution of different component and an integrated lattice structure may manifest an enhanced synergistic effect compared to the mechanical mixture. In this paper, multicomponent Zn 0.12 Co 0.88 CO 3 composite with high tap density (2.11 g cm −3 ) synthesized via one-step solvothermal method, which exhibits hexagonal structure similar to that of the monocomponent cobalt carbonate (CoCO 3 ). The Zn-substitution could significantly improve the charge and discharge capacity of CoCO 3 from 1001.6 mAh g −1 to 1253.7 mAh g −1 at 0.2 C. When the Zn-substituted CoCO 3 is embedded in carbon nanotubes (CNT) network, the rate performance of Zn 0.12 Co 0.88 CO 3 can be improved greatly. The resulting Zn 0.12 Co 0.88 CO 3 /CNT exhibits outstanding rate performance, delivering a reversible capacity of 1098.4, 840.8, and 610.7 mAh g −1 at 0.5, 1 and 2 C, respectively. The excellent performance of Zn 0.12 Co 0.88 CO 3 /CNT is ascribed to the unique micro-sphere structure with carbon nanotubes. The elastic CNT networks are introduced to wrap the Zn 0.12 Co 0.88 CO 3 , which can not only provide a highly conductive network for electron transfer, but also serve as a buffer to alleviate the aggregation and volume changes of Zn 0.12 Co 0.88 CO 3 nanoparticles. The Zn 0.12 Co 0.88 CO 3 /CNT composite may serve as a novel high-capacity LIBs anode material for practical application, and a facile strategic approach is introduced for the full-molar-ratio synthesis of multicomponent composites. [ABSTRACT FROM AUTHOR]

A graphene/carbon nanotube (CNT)/sulfur (denoted GCS) hybrid with interconnected structure is prepared through a one-pot self-assembly approach initiated by l -ascorbic acid reduction under a mild condition. In such a solution-based assembly process, the formation of an interconnected graphene/CNT conductive network is accompanied by the uniform loading of sulfur, whose fraction is as high as of 70 wt%. The as-prepared GCS hybrid delivers an initial capacity of 1008 mAh g −1 at 0.3C and maintains 704 mAh g −1 after 100 cycles. Remarkably, at a high rate of 1.0C, the cathode shows an excellent cyclic performance with a capacity of 657 mAh g −1 after 450 ycles and the capacity decay is only 0.04% per cycle. Moreover, the superior rate performance of GCS hybrid is attributed to the conductive network formed by interconnected graphene sheets and CNT, which supply an unimpeded and continuous path for electron and Li ion transfer and accommodate the volume variation of sulfur during charge/discharge cycling. In addition, the residual functional groups on GCS can retain intimate contact of the conducting matrix with sulfur and effectively confine the diffusion of polysulfides. This study gives an eco-friendly and highly effective solution-based approach for carbon–sulfur electrode for lithium–sulfur battery. [ABSTRACT FROM AUTHOR]

Abstract: Enhancement of thermal conductivity of natural flake graphite/polymer (NFG/polymer) composite sheets, prepared with tape casting method, was studied by adding carbon-based nano-fillers including carbon black, carbon nanotube (CNT) and graphene. The in-plane thermal conductivities of the composites, i.e., the thermal conductivities along the tape casting plane, were measured. The improvement of thermal conductivities of the composites was observed to be up to 24% by adding CNT and 31% by adding graphene at 10wt.%. Micro-structures of the NFG/polymer composites were revealed by X-ray diffraction patterns and field emission scanning electron microscopy images to delineate the mechanism of thermal conductance in the composites. From the observed structure, a new thermal conductivity model for the composites with CNT and graphene additives was constructed based on a bridging mechanism. The new model applies well to the measured thermal conductivities of the as-prepared samples. It is expected that the model could also be applied well to composites added with other homologous materials for bridging thermal contacts. [Copyright &y& Elsevier]

Abstract: Bamboo-shaped carbon nanotubes (BCNTs), which were synthesized through chemical vapor deposition by using cresol as the carbon source, were explored as Pt catalyst support in comparison with conventional carbon nanotubes (CNTs) and Vulcan XC carbon blacks. The pyrolysis of cresol produced a large amount of pentagon defects introduced in the walls of BCNTs, which could possess higher chemical activity and stronger interaction with metal particles. After a mild purification, the BCNTs exhibited more oxygen-containing functional groups than CNTs, as shown by Fourier transform infrared spectra and cyclic voltammetry. The formed oxygen-containing functional groups as well as the pentagon defects could act as uniform active sites for metal particle loading. By ethylene glycol reduction, highly dispersed Pt nanoparticles with a narrow size distribution of 2–3nm were easily supported on BCNTs, as shown by transmission electron microscope. The Pt/BCNT catalyst showed higher electro-catalytic activity on the methanol oxidation than the Pt/CNT and Pt/Vulcan XC catalyst, which could be largely ascribed to the highly dispersed Pt nanoparticles due to the introduced pentagon defects in the tube-walls (comparing with Pt/CNT) and the graphitic nanotube network that could provide good electron conduction (comparing with Pt/Vulcan XC). [Copyright &y& Elsevier]

Abstract: Bamboo-shaped carbon nanotubes (BCNTs), with a large amount of pentagon defects introduced in the walls, were explored as the support of high loaded Pt–Ru catalysts for the anode of direct methanol fuel cells (DMFCs) in comparison with conventional carbon nanotubes (CNTs) and Vulcan XC carbon black. By ethylene glycol reduction, Pt–Ru catalysts with a high loading (60wt%) and uniform particle size of 2–3nm were uniformly deposited on BCNTs; while 60wt% Pt–Ru catalysts on CNTs resulted in significant agglomeration. The Pt–Ru/BCNT catalyst showed the highest activity on methanol oxidation in cyclic voltammetry and highest performance as the anode in a DMFC single cell. Such an enhancement was largely ascribed to an enhanced interaction of the introduced pentagon defects with Pt–Ru, which could promote a high loading and well dispersion of Pt–Ru catalysts and the charge transfer from Pt–Ru to the tubes. [Copyright &y& Elsevier]