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Abstract: Patterning is an essential and important process for the future use of single-walled carbon nanotube (SWCNT) thin films (TFs) in electronic devices. Different from traditional Si based electronic materials, SWCNTs can be easily etched when exposed to an oxidative atmosphere. Here we propose a gas exposure method to pattern SWCNT TFs on flexible polymeric substrates, without using vacuum and high temperature treatment. By simply exposing them to ozone for 3min, a high quality SWCNT TF (35–40nm in thickness) pattern is obtained on a poly (ethylene terephthalate) substrate. It is found that the ozone can chemisorb on, functionalize and etch SWCNTs and then destroy the electrically conductive network of SWCNT TFs, which causes a fast resistance increase and achieves efficient SWCNT TF patterns. The proposed patterning method has the advantages of high efficiency, low cost and scale-up ability, and more importantly, it is suitable for assembling flexible electronic devices, indicating prospects for the low-cost and large-scale manufacture of such items. [Copyright &y& Elsevier]

Abstract: Graphene has attracted great interest for its excellent mechanical, electrical, thermal and optical properties. It can be produced by micro-mechanical exfoliation of highly ordered pyrolytic graphite, epitaxial growth, chemical vapor deposition, and the reduction of graphene oxide (GO). The first three methods can produce graphene with a relatively perfect structure and excellent properties, while in comparison, GO has two important characteristics: (1) it can be produced using inexpensive graphite as raw material by cost-effective chemical methods with a high yield, and (2) it is highly hydrophilic and can form stable aqueous colloids to facilitate the assembly of macroscopic structures by simple and cheap solution processes, both of which are important to the large-scale uses of graphene. A key topic in the research and applications of GO is the reduction, which partly restores the structure and properties of graphene. Different reduction processes result in different properties of reduced GO (rGO), which in turn affect the final performance of materials or devices composed of rGO. In this contribution, we review the state-of-art status of the reduction of GO on both techniques and mechanisms. The development in this field will speed the applications of graphene. [Copyright &y& Elsevier]

Abstract: We report a simple but highly-effective hydrohalic acid reducing method to reduce graphene oxide (GO) films into highly conductive graphene films without destroying their integrity and flexibility at low temperature based on the nucleophilic substitution reaction. GO films reduced for 1h at 100°C in 55% hydroiodic (HI) acid have an electrical conductivity as high as 298S/cm and a C/O ratio above 12, both of which are much higher than films reduced by other chemical methods. The reduction maintains good integrity and flexibility, and even improves the strength and ductility, of the original GO films. Based on this reducing method, a flexible graphene-based transparent conductive film with a sheet resistance of 1.6kΩ/sq and 85% transparency was obtained, further verifying the advantage of HI acid reduction. [ABSTRACT FROM AUTHOR]

Review: 279 refs. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li-S) batteries are one of the most promising next-generation secondary battery systems for meeting increasing energy storage demands due to their high theoretical energy density. However, the commercialization of Li-S batteries is hindered by the low electrical conductivity of sulfur and the severe polysulfide shuttling problem. Here, we report the easy synthesis of a nitrogen-doped multi-functional nanocarbon hybrid decorated with nickel nanoparticles and its use in a conductive membrane for an integrated electrode/separator in Li/dissolved polysulfide batteries. The nitrogen-doping produces desirable polysulfide immobilization by enhanced adsorption and chemical bonding. The nickel nanoparticles act as electrocatalysts to accelerate the kinetics of sulfur conversion reactions. The assembled conductive membrane acts both as a conductive scaffold and a polysulfide adsorption layer that allows efficient charge transfer and effectively prevents polysulfide diffusion. Consequently, a Li/polysulfide cell with a high sulfur loading demonstrates excellent cycling stability with a low capacity decay rate of 0.115% per cycle over 200 cycles, showing great promise for use in advanced Li–S batteries. [ABSTRACT FROM AUTHOR]

Li metal is the ultimate choice for the anode in next‐generation high energy density rechargeable batteries. However, undesired dendrite growth, dead Li formation, and a large volume change of the lithium metal anode lead to severe safety hazards such as short‐circuiting, fire, or even explosion. Graphene oxide (GO) in large areas has been prepared as the Li metal host via a continuous centrifugal casting method. Aligned microchannels are then fabricated in it by a simple punching method using 3D printed templates. The GO matrix effectively regulates the lithium plating/stripping behavior while the aligned channels uniformly distributes the Li‐ion flux and provides short Li‐ion diffusion paths. The Li/ holey GO composite is flexible with a controllable thickness from 50 to 150 µm, which corresponds to capacities from 9.881 to 27.601 mAh cm−2. As a result, the anode has a low overpotential of 30 mV after 100 h, a high capacity of ≈3538 mAh g−1 (91.4% of the theoretical capacity), and a superior rate ability of up to 50 C with a LiFePO4 cathode. The holey GO/Li electrode is also paired with other cathodes and used in pouch cells, indicating its suitability for various high‐energy battery systems. [ABSTRACT FROM AUTHOR]

A graphene-coated polymer separator was developed for lithium–selenium batteries with pure selenium powder as the active material. The structure is a simple yet effective strategy for improving Li–Se battery's electrochemical performance, yielding long cycle life up to 1000 cycles with high capacity and excellent rate behavior. [ABSTRACT FROM AUTHOR]

Deteriorating interfacial contact under mechanical deformation induces large cracks and high charge transfer resistance, resulting in a severe capacity fading of flexible lithium‐ion batteries (LIBs). Herein, an oxygen plasma treatment on a polymer separator combined with high‐speed centrifugal spraying to construct ultrastable interfacial contacts is reported. With the treatment, abundant hydrophilic oxygen‐containing functional groups are produced and ensure strong chemical adhesion between the separator and the active materials. With single walled carbon nanotubes (SWCNTs) sprayed onto the active materials, a dense thin film is formed as the current collector. Meanwhile, the centrifugal force caused by high‐speed rotation together with van der Waals forces under fast evaporation produces a much closer interface between the current collector and the active materials. As a result of this ultrastable interfacial interaction, the integrated electrode shows no structural failure after 5000 bending cycles with the charge‐transfer resistance as low as 35.8% and a Li‐ion diffusion coefficient nearly 19 times of the untreated electrode. Flexible LIBs assembled with these integrated electrodes show excellent structural and electrochemical stability, and can work steadily under various deformed states and repeated bending. This work provides a new technique toward rational design of electrode configuration for flexible LIBs. [ABSTRACT FROM AUTHOR]

Large‐area fabrication and stacking of various nanometer‐thick functional layers from solutions is essentially important for the construction of flexible thin‐film optoelectronic devices, but very challenging. The existing fabrication methods suffer from either non‐uniformity caused by the coffee‐ring effect or serious solution waste (excess of 90% for spin coating), and are hard to scale up and create stacks. Here, it is shown that centrifugal casting is a universal, scalable, and efficient method to fabricate uniform nanometer‐thick films and their stacks of various materials. The coffee‐ring effect is effectively suppressed, the solution utilization ratio is higher than ≈61%, and the films/stacks show a smooth surface/high‐quality interface. Using this method, flexible quantum dot light‐emitting diode displays with uniform luminance in a large lighting area of ≈115 cm2 that have not been achieved even on rigid substrates by the existing methods, are realized. This efficient and low‐cost solution processing method paves a way for large‐area fabrication of various flexible thin‐film optoelectronic devices. [ABSTRACT FROM AUTHOR]

Proton transport in nanochannels under humid conditions is crucial for the application in energy storage and conversion. However, existing materials, including Nafion, suffer from limited conductivity of up to 0.2 siemens per centimeter. We report a class of membranes assembled with two-dimensional transition-metal phosphorus trichalcogenide nanosheets, in which the transition-metal vacancies enable exceptionally high ion conductivity. A Cd0.85PS3Li0.15H0.15 membrane exhibits a proton conduction dominant conductivity of ~0.95 siemens per centimeter at 90° Celsius and 98% relative humidity. This performance mainly originates from the abundant proton donor centers, easy proton desorption, and excellent hydration of the membranes induced by cadmium vacancies. We also observed superhigh lithium ion conductivity in Cd0.85PS3Li0.3 and Mn0.77PS3Li0.46 membranes. [ABSTRACT FROM AUTHOR]

Abstract: One of the most attractive research areas in lithium-ion batteries (LIBs) is to design elaborate nanostructure of the electrode, which has been considered as keys to solve the problems such as the low energy density, slow lithium ion and electron transport, and the large volume change of electrode materials during cycling processes. Here, mesoporous Co3O4 with controllable structures was directly grown on a graphene membrane by hydrothermal reaction followed by annealing treatment, and used as an integrated anode in LIBs without using metallic current collector, binder and conductive additive. The light graphene membrane as current collector with high electrical conductivity and stability contributes to the high energy density of LIBs. A mesoporous structure with enough space is beneficial to lithium ion diffusion and strain buffer of Co3O4 during discharge/charge processes, rendering the electrodes high performance. The integrated electrode shows good rate capability and impressive cycling stability without capacity loss over 500 cycles under a high current density of 500 mA g−1. [Copyright &y& Elsevier]

Abstract: A method for the bulk growth of mono- to few-layer graphene on nickel particles by chemical vapor deposition from methane at atmospheric pressure is described. A graphene yield of about 2.5% of the weight of nickel particles used was achieved in a growth time of 5min. Scanning and transmission electron microscopy, Raman spectroscopy, thermogravimetry, and electrical conductivity measurements reveal the high quality of the graphene obtained. Suspended graphene can be prepared during this process, bridging the gaps between nearby nickel grains. After the growth of graphene the nickel particles can be effectively removed by a modest FeCl3/HCl etching treatment without degradation of the quality of the graphene sheets. [Copyright &y& Elsevier]