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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]

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]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.comnet.2006.08.015 Byline: Caixia Chi, Ruibing Hao Keywords: Feature interaction testing; Finite state machine; Dual graph; Euler tour; Chinese postman tour Abstract: This paper proposes two techniques to generate test sequences to check the conformance of an implementation of a feature-rich communication system to its specification, as well as to detect the interactions between the features of the system. Concepts color span and feasible combination of features are introduced to measure the extent and possibility of the interactions between different features. Several algorithms are proposed to produce an approximate minimum-cost and minimum color span tour of the transition graph of a finite-state machine. Test generation using the proposed algorithms for the SIP-based Internet telephony end system and for the Link Management Protocol is reported. Author Affiliation: Bell Labs Research China, Lucent Technologies, Beijing 100080, China Article Note: (miscellaneous) Responsible Editor: H. Rudin

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]

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]

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]

Abstract A stable graphene anode with high storage Li+ capacity for lithium-ion batteries (LIBs) is to be desired for energy storage. In the present paper, a new scalable method is adopted for preparation of three-dimensional porous graphene microspheres (3DGPM) by a template sacrificing method. The 3DGPM were utilized as an anode for lithium ion batteries (LIBs). The macrostructure of the 3DGPM anode was characterized by the scanning electron microscope, transmission electron microscope and X-ray diffraction. As anode for LIBs, the first discharge/charge capacities of the 3DGPM are 851.1 and 402.4 mAh g−1 at a current density of 0.1 A g−1. The 500th discharge capacity of the 3DGPM anode at a current density of 2 A g−1 is 245.8 mA h g−1. Besides, the 3DGPM exhibit low charge transfer resistance and high Li-ion diffusivities. The porous nanospheres of graphene offer voids for volume expansion and pathways for fast electron transfer during repeated cycling. We believe that the specific micro-/nano-hollow microspherical structure is the main origins of their high electrochemical storage Li performance. Highlights • 3D porous graphene microspheres were fabricated by template sacrificing method. • The specific hollow graphene structure was detected. • The 3D porous graphene microspheres were utilized as an anode for lithium ion batteries • The electrochemical properties of graphene based anode are improved. [ABSTRACT FROM AUTHOR]

To circumvent the imbalances of electrochemical kinetics and charge-storage capacity between Li + ion battery anodes and capacitive cathodes in lithium-ion capacitors (LICs), dual carbon based LICs are constructed and investigated extensively. Herein, S, O dual-doped 3D net-like porous carbon (S-NPC) is prepared using waste paper as the carbon source through a facile solvothermal treatment and chemical activation. Benefiting from the combination effect of the rich S,O-doping (about 2.1 at% for S, and 9.0 at% for O), high surface area (2262 m 2 g -1 ) and interconnected porous network structure, the S-NPC-40 material exhibits excellent electrochemical performance as both cathode material and anode material for LICs. S, O doping not only increases the pseudocapacity but also improves the electronic conductivity, which is beneficial to reduce the mismatch between the two electrodes. The S-NPC-40//S-NPC-40 LIC delivers high energy densities of 176.1 and 77.8 W h kg -1 at power densities of 400 and 20 kW kg -1 , respectively, as well as superior cycling stability with 82% capacitance retention after 20 000 cycles at 2 A g -1 . This research provides an efficient method to convert waste paper to porous carbon electrode materials for high performance LIC devices., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Vanadium oxide (V 2 O 5 ), as a potential positive electrode for sodium ion batteries (SIBs), has attracted considerable attention from researchers. Herein, amorphous and crystalline V 2 O 5 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 V 2 O 5 (a-V 2 O 5 ) cathode and crystalline V 2 O 5 (c-V 2 O 5 ) 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-V 2 O 5 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-V 2 O 5 cathode possesses higher reversible capacities than the c-V 2 O 5 cathode at low current densities, whereas it is inversed at high current densities. The c-V 2 O 5 cathode shows faster capacity recovery from 5120 to 40 mA g -1 than the a-V 2 O 5 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-V 2 O 5 cathode shows a higher discharge capacity than its c-V 2 O 5 counterpart. The different electrochemical performance of a-V 2 O 5 and c-V 2 O 5 cathodes during various electrochemical processes can provide a rational selection of amorphous or crystalline V 2 O 5 cathode materials for SIBs in their practical applications to meet the variable requirements.