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Given the abundance of sodium resources, sodium-ion batteries (SIBs) have been considered as one of the candidates for storing energy on a large scale. However, the slower sodium ion transport in the electrode limits its use. Here, we report a binder free Zn2GeO4-graphene Ni foam integrated anode for Na ion storage. The obtained integrated anode was supported by nickel foam without binder, the Zn2GeO4 exhibits nanotube structure, and the graphene was coating on the Zn2GeO4. The Zn2GeO4 nanorods are able to coalesce with each other to form porous structures. The binder free Zn2GeO4-graphene Ni foam integrated anode electrode delivered a discharge capacity of 427.7 mAh g−1 at 0.1 A g−1 after 200 cycles. And at a high current density of 2 A g−1 a favorable rate capacity of 391.4 mAh g−1 could be achieved, twice that of the Zn2GeO4-graphene powder electrode. The outstanding electrochemical performance can be attributed to the synergistic effect between in situ grown Zn2GeO4 nanorods and graphene sheets, which enhanced the conductivity and stabilized the electrode structure during the cycling process, as well as the improved electrochemical reaction kinetics due to in-situ growth. This work sheds light on the design of Ge-based ternary oxide anodes and provides a promising anode for high performance SIBs. [ABSTRACT FROM AUTHOR]

Porous carbons (PCs) have been widely investigated as electrode materials for supercapacitors. However, during the preparation process, intense pore formation reactions result in an amorphous carbon structure, which limits the rate performance of the electrode material. Herein, coal is chosen as a carbon source and making use of different reaction characteristics of vitrinite and inertinite with a KOH activator, an interconnected porous structure carbon material with an abundant graphite microcrystalline structure is obtained; the organic relationships between the ratio of vitrinite and inertinite, carbonization conditions, material structure and capacity performance were researched. At the ratio of vitrinite to inertinite of 1 : 2, the sample shows a specific surface area of 2507 m2 g−1 and its ID1/IG is 1.31, which is lower than that of raw coal (1.36). Due to the synergistic effect of the pore structure and graphite microcrystals, PC-900-40 exhibits an improved specific capacitance of 229.40 F g−1 at a current density of 1.0 A g−1, and even at a high current density of 10.0 A g−1 it delivers a specific capacitance of 170.04 F g−1. The PC-900-40//PC-900-40 symmetrical capacitor retains 96% of its initial capacitance after 20 000 cycles. [ABSTRACT FROM AUTHOR]

Electrochemical hydrogen storage, which can be performed at ambient temperatures and mild pressures, is regarded as a promising technique to store hydrogen safely and efficiently. In this study, the electrochemical hydrogen storage performance of activated carbon was improved by synthesizing a graphitized microcrystalline porous carbon material through a facile one-step catalytic carbonization activation procedure using coal as the raw material. Owing to the synthetic effect of the conductive network and the hierarchical porous structure, the carbon electrode exhibited high capacity, excellent rate performance, and substantial cycling stability for electrochemical hydrogen storage. The hydrogen storage capacity of the material was 278 mA h g−1 at a current density of 100 mA g−1, with considerable capacity retention of 86% after 50 cycles. The electrode exhibited superior rate capacity of 260 mA h g−1 at 200 mA g−1. Porous carbon with microcrystalline graphite was demonstrated to be an efficient electrode for electrochemical hydrogen storage. [ABSTRACT FROM AUTHOR]

Due to the potential applications of transition metal nitrides in modern electronic and spintronic devices, we have systematically studied the magnetic properties of δ-MoN induced by the Mn dopant, with the goal of identifying the origin of magnetism and figuring out the magnetic coupling mechanism between the Mn dopants. Based on the density functional theory, one Mn atom doped at different Mo sites (2a and 6c in the International Tables) in the unit cell of δ-MoN was firstly studied. It was found that the Mn dopant located at the 2a or 6c site leads to significant spin splitting of the density of states, suggesting that the Mn doping induces magnetism in δ-MoN. The calculations were then extended to a 2 × 1 × 2 supercell, which contains two impurity Mn atoms. Detailed analysis reveals that the different couplings of the Mn–Mn pair cannot be simply attributed to the different Mn–Mn distances but are closely related to the electronic processes that take place in the segment (–N– or –N–Mo–N–) that connects two Mn dopants. The mechanisms responsible for the FM/AFM coupling of the Mn–Mn pairs are the superexchange and the p–d exchange mediated by the N atoms, and the d–d coupling between the host Mo atom and the Mn dopant. [ABSTRACT FROM AUTHOR]

Gallium (Ga) electrodes have been used as anodes in Li-ion batteries, due to their low-melting-point and self-healing properties. However, the use of Ga without a binder or a conductive agent together as the anode material is rare. In this study, AlCl3 was added as an additive to the electrolyte formed by [EMIm]Cl and GaCl3. The obtained binder-free Ga particles were used as the anode of the Li-ion battery; the initial specific capacity was 528.2 mA h g−1 and the initial coulombic efficiency was 97.8%. After 100 cycles, the specific capacity of discharge was 441.6 mA h g−1 at 0.1C. Ga particles obtained from ionic liquids can be used to improve the cycling stability of anodes in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

The density and pore diameter of aluminum (Al) films have an important influence on the resultant film applications, especially in the field which require extremely high-density, uniform Al films. In this study, Al was electrodeposited from 1-ethyl-3-methyl imidazolium chloride ([EMIm]Cl) ionic liquid onto a Ni substrate using AlCl3 as the Al source. The results show that the concentration of the electrolyte was the crucial factor governing the microstructure of the electrodeposited continuous and dendrite-free Al film. The obtained continuous, dendrite-free Al film was used as the anode of a Li-ion battery. The obtained Al films delivered a first specific capacity reaching 1492 mAh g−1 in the Li-ion battery and effectively improved the corrosion resistance of the Ni substrate. [ABSTRACT FROM AUTHOR]

In this work, a novel pyrrolic nitrogen-doped carbon sandwiched monolayer MoS2 hybrid was prepared. This sandwiched hybrid vertically anchors on graphene oxide as anode materials for sodium-ion batteries. Such electrode was fabricated by facile ionic liquid-assisted reflux and annealing methods. Owing to rational structure and enhancement from pyrrolic nitrogen dopant, this unique MoS2/C-graphene hybrid exhibits reversible specific capacity of 486 mAh g−1 after 1000 cycles with a low average fading capacity of 0.15 mAh g−1 (fading cyclic rate of ca. 0.03% per cycle). A capacity of 330 mAh g−1 is remained at the current densities of 10.0 A g−1. The proposed strategy provides a convenient way to create new pyrrolic nitrogen-doped hybrids for energy field and other related applications. [ABSTRACT FROM AUTHOR]

Germanium (Ge) is an important semiconductor material in optoelectronic devices and is being researched in energy storage fields. Ge nanostructure materials with different morphologies may lead to distinctly different application performances. In this work, Ge nanorod architectures were successfully template-free electrodeposited on ITO substrate from the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([Emim]Tf2N) containing dissolved GeCl4 with the assistance of UV light. The UV irradiation influences the conformation of imidazolium rings of [Emim]+ adsorbed during the deposition process. A solution template has been formed on the surface of the electrode which inhibited the lateral growth of Ge nuclei and promoted the growth of Ge nanorod structures. Consequently, the coral-like Ge nanorod bundles (NRBs) has been obtained. This method provides attractive prospects for the other semiconductor nanorod structures. [ABSTRACT FROM AUTHOR]

Heterogeneous interfaces interaction and multiscale nanostructures in two-dimensional (2D) materials hybrids are critically significant for realizing rate capability and long-life cycling performance. However, to strike a balance between minimizing the carbon content and maximizing the heterogeneous interfaces remains a critical challenge in nanoarchitectures for hybrid few-layers MoS2 with various carbonaceous materials. Here we present the ordered macroporous few-layered MoS2/C hybrid nanoarchitectures via a facile scalable in situ hybridization and spatial confinement strategies. Such hybrid strategies can maximize the MoS2 loading and restriction of MoS2 to a ultrasmall reaction. The optimized as-prepared hierarchical MoS2/C hybrids exhibit an initial capacity up to 631.2 mAh g−1 with a high first columbic efficiency of 81.16% for sodium-ion batteries (BILs) at 200 mA g−1. And, the electrodes display a high reversible capacity of 330.4 mAh g−1 with a long cycle life, superior cycling stability and excellent high-rate performance demonstrated rational designed hybrid architecture using as the electrodes in SIBs. This strategy could be proven to be an effective method for stabilizing the cyclability and improving in rechargeable rate performance for SIBs. [ABSTRACT FROM AUTHOR]

Germanium has emerged as a promising Li ion battery anode material due to its high theoretical capacity. The in situ growth of Ge nanowires on current collectors (binder-free electrodes) has attracted much attention owing to their good electrical contact, excellent strain accommodation ability, promising material durability and short Li ion diffusion distance. Herein, we report a facile and efficient technique to synthesize Ge nanowire cluster arrays (Ge NWCAs) on nickel foam through an ultraviolet light (UV) assisted, template-free electrodeposition process from 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([Emim]Tf2N). As a binder-free anode material, a Ge NWCA electrode exhibits a specific capacity of 1612 mA h g−1 and retains 740 mA h g−1 up to 200 cycles at a current rate of 0.2C. The Ge NWCA electrode affords excellent rate capacity at 0.1C–2C and retains specific capacity as high as 959 mA h g−1 at 2C. Furthermore, the specific capacity well recovers to 998 mA h g−1 when the rate is reduced from 2C to 0.1C. UV assisted ionic liquid electrodeposition might open up a new avenue for the synthesis of semiconductor nanostructures. [ABSTRACT FROM AUTHOR]

Achieving appropriate cycling stability for metal sulfides used as anodes in Li-ion batteries remains highly challenging because of structural collapse or low conductivity. Herein, a novel composite was designed as an anode material for Li-ion batteries. This unique architecture has the advantages of a large interface area, numerous channels for Li+ and electron transport, and a porous structure that facilitates electrolyte infiltration and buffers the volume expansion. As expected, this composite exhibits good cycling stability, high reversible capacity, and high rate capability, delivering a high discharge capacity of 1511.6 mA h g−1 and a high first columbic efficiency of 83.27%. The reversible capacities of graphitic-carbon network material (GCNM) electrodes are 1112 mA h g−1 at a current density of 0.1 A g−1 after 100 cycles, and they show superior rate capabilities. This GCNM composite demonstrates great potential for applications in power sources for flexible and lightweight electronic devices. [ABSTRACT FROM AUTHOR]

Vanadium oxide (V2O5), as a potential positive electrode for sodium ion batteries (SIBs), has attracted considerable attention from researchers. Herein, amorphous and crystalline V2O5 cathodes on a graphite paper without a binder and conductive additives have been synthesized via facile anodic electrochemical deposition following different heat treatments. Both the amorphous V2O5 (a-V2O5) cathode and crystalline V2O5 (c-V2O5) cathode show good rate cycling performance and long cycling life. After five rate cycles, the reversible capacities of both the cathodes were almost unchanged at different current densities from 40 to 5120 mA g−1. Long cycling tests with 10 000 cycles were carried out and the two cathodes exhibit excellent cycling stability. The c-V2O5 cathode retains a high specific capacity of 54 mA h g−1 after 10 000 cycles at 2560 mA g−1 and can be charged within 80 s. Interestingly, the a-V2O5 cathode possesses higher reversible capacities than the c-V2O5 cathode at low current densities, whereas it is inversed at high current densities. The c-V2O5 cathode shows faster capacity recovery from 5120 to 40 mA g−1 than the a-V2O5 cathode. When discharged at 80 mA g−1 (long discharge time of 140 min) and charged at 640 mA g−1 (short charge time of 17 min), the a-V2O5 cathode shows a higher discharge capacity than its c-V2O5 counterpart. The different electrochemical performance of a-V2O5 and c-V2O5 cathodes during various electrochemical processes can provide a rational selection of amorphous or crystalline V2O5 cathode materials for SIBs in their practical applications to meet the variable requirements. [ABSTRACT FROM AUTHOR]

Ge nanotube array anodes are prepared by template-assisted electrodeposition from an ionic liquid to obtain superior cycling performance. They show remarkable cycling ability at 0.2 C, with a very high initial discharge capacity of 1641 mA h g−1 and a charge capacity of 1260 mA h g−1. After 250 cycles the capacity retention is 98% relative to that at the 50th cycle. [ABSTRACT FROM AUTHOR]

Due to the potential applications of transition metal nitrides in modern electronic and spintronic devices, we have systematically studied the magnetic properties of δ-MoN induced by the Mn dopant, with the goal of identifying the origin of magnetism and figuring out the magnetic coupling mechanism between the Mn dopants. Based on the density functional theory, one Mn atom doped at different Mo sites (2a and 6c in the International Tables) in the unit cell of δ-MoN was firstly studied. It was found that the Mn dopant located at the 2a or 6c site leads to significant spin splitting of the density of states, suggesting that the Mn doping induces magnetism in δ-MoN. The calculations were then extended to a 2 × 1 × 2 supercell, which contains two impurity Mn atoms. Detailed analysis reveals that the different couplings of the Mn–Mn pair cannot be simply attributed to the different Mn–Mn distances but are closely related to the electronic processes that take place in the segment (–N– or –N–Mo–N–) that connects two Mn dopants. The mechanisms responsible for the FM/AFM coupling of the Mn–Mn pairs are the superexchange and the p–d exchange mediated by the N atoms, and the d–d coupling between the host Mo atom and the Mn dopant. [ABSTRACT FROM AUTHOR]

A novel closed-loop feedback TCP/AQM (Transfer Control Protocol/Active Queue Management) model is proposed in this paper using a discrete-time Markov chain, and a way to calculate the equilibrium distribution of this model is given. In the model, system time is divided into time slots, the bottleneck router queue model and TCP window size model in each slot are analyzed. Finally, by combining adjacent slots, an integrated TCP/AQM analytical model is developed. By this model, the average values of packets dropping ratio and queue length in the router and TCP sending rate can be estimated, hence, this model could be a useful tool for the analysis of AQMs and support the development of new AQM schemes theoretically. The proposed TCP/AQM model is extended to a TCP-UDP (Control User Datagram Protocol)/AQM model, to analyze the TCP/AQM system performance when UDP flows exist. By implementing this model on Matlab, we compare its solutions to NS2 simulated solutions, then the validity of the model to analyze the closed-loop feedback TCP/RED (Random Early Detection) system is verified. [ABSTRACT FROM AUTHOR]

This paper builds a new traffic assignment model for Internet. The routing policy based on this model can realize load splitting in a network automatically, which overcomes the shortcoming of OSPF and satisfies the load balancing requirement of IETF. [ABSTRACT FROM AUTHOR]