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Gram-scale synthesis of F-doped Ni 3 V 2 O 8 nanorods with abundant oxygen vacancies has been explored via molten-salt method. The size and morphology of the Ni 3 V 2 O 8 can be dominated by the fluorinion. When served as anode materials, the F-doped Ni 3 V 2 O 8 nanorods exhibit high initial Coulombic efficiency (ICE) of 90.8%, better cyclability (983 mAh g−1 after 100 cycles at 200 mA g−1) and superior long-term stability (616 mAh g−1 after 500 cycles at 2000 mA g−1). The high ICE and excellent electrochemical properties may be originated from the fast conversion reaction upon lithiation/delithiation and the good electronic conductivity induced by the small size and oxygen vacancies. [ABSTRACT FROM AUTHOR]

Developing highly efficient host materials to suppress the lithium polysulfides (LiPSs) shuttling and accelerate the Li 2 S conversion is essential for advanced lithium-sulfur (Li–S) batteries. In this work, based on first principles computations, we explored transition metal embedded C 2 N monolayers (M@C 2 N, M = Mn, Fe, Co, Ni, Cu) as host materials and catalysts for Li–S batteries. Our results show that M@C 2 N monolayers could prevent the LiPSs shuttling with strong adsorption energies towards LiPSs, due to the synergistic effect of M-S and Li–N bonds. Moreover, the presence of transition metal atoms in the C 2 N could improve its electric conductivity. On the whole lithiation process, all the adsorbed systems are still conductive, which is helpful to boost the sulfur utilization. Importantly, M@C 2 N monolayers could promote the Li 2 S decomposition and thus enhance the oxidation kinetics of Li 2 S back to sulfur. Among them, Co@C 2 N monolayer is the best host material, which possesses the largest adsorption energies with LiPSs and the lowest decomposition energy of Li 2 S. This work opens a new avenue for the development of host materials with excellent catalytic activity towards LiPSs, and also sheds light on M@C 2 N as superior cathode materials. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS 2) has become a potential anode material for sodium-ion batteries (SIBs) by showing decent cell performance but it suffers poor electronic conductivity and large volume expansion during sodiation. Here we design a nanocomposite with hollow nitrogen doped carbon and polypyrrole modified MoS 2 for improving the performance for SIBs. The designed nanocomposite shows a much-improved electronic conductivity and the design of the architecture provides sufficient channels for mass transport and accommodates large volume change. This C@MoS 2 @PPy anode delivers a high specific capacity of 713 mAh g−1 at 0.1 A g−1 for 100 cycles, and an excellent rate capacity of 294 mAh g−1 at 5 A g−1 for 500 cycles. This specific architecture of C@MoS 2 @PPy could guide the future design of the electrode material in SIBs and its superior electrochemical performance indicates the great potential application for SIBs. Hollow C@MoS 2 @PPy nanocomposites were designed and fabricated using FeOOH@C as sacrificial template, which exhibit excellent cycle stability and good rate capacity. Image 1 • Ultrathin MoS 2 nanosheets confined in N-doped carbon and PPy are prepared and used as high performance electrode for SIBs. • C@MoS 2 @PPy with much stronger Mo N bonds can effectively enhance the mechanical stability. • The N-doped carbon nanotubes and PPy provide binary channels for accelerating the Na-ion transport. • C@MoS 2 @PPy delivers a specific capacity of 294 mAh g−1 after 500 cycles at 5 A g−1. [ABSTRACT FROM AUTHOR]

The design and fabrication of the materials to improve their performance are crucial for energy storage of lithium-ion batteries and supercapacitors. Herein, the CuCo 2 S 4 nanocrystallites grown on N-doped amorphous carbon coated CNTs are synthesized via a facile solvothermal method (CNTs@NC@CuCo 2 S 4 ). The N-doped amorphous carbon layer with functional groups can effectively strengthen the adhesion between CNTs matrix and CuCo 2 S 4 nanocrystallites. The combination of nanocrystallites and the CNTs not only shortens the diffusion path of the electrolyte, but also enhances the electrical conductivity of the electrode. As a result, the CNTs@NC@CuCo 2 S 4 displays excellent electrochemical performance both in lithium-ion batteries and supercapacitors. The reversible capacity can be retained at 783 mAh g −1 after 100 cycles at the current density of 100 mA g −1 . And the discharge capacity of 507 mAh g −1 is still maintained after 60 cycles even at high rate of 5000 mA g −1 . As the electrode for supercapacitors, the CNTs@NC@CuCo 2 S 4 delivers good capacitive performance with high capability (1604 F g -1  at 1 A g −1 ), good rate capability, and enhanced cycling stability, with 93.6% capacitance retention after 2000 cycles at the current density of 2 A g −1 . [ABSTRACT FROM AUTHOR]

Transition metal chalcogenides are considered as promising materials for lithium-ion battery, however, the application in practical devices is still hampered by their poor cycling performance and rate capability. In this work, we design and construct sandwich-like Cu 2-x Se@C@MoSe 2 nanosheets to enhance the cycling and rate performances of Cu 2-x Se. The reversible capacity could be retained at 432 mAh g −1 after 100 cycles at the current density of 100 mA g −1 . At 2000 mA g −1 , the specific capacity still retains at 163 mAh g −1 . The improved lithium storage performance can be attributed to its structural features, which enhance the electrical conductivity, buffer the volume change as well as increase their structural stability during cycling. [ABSTRACT FROM AUTHOR]

Bi 2 Se 3 with layered structure has been considered as a promising host for Li ion batteries due to its high electrical conductivity. However, the disadvantages such as dissolution loss of selenium species and the large volume expansion extremely hinder its practical application. Here, the electrochemical performance is improved by synthesizing CNTs@C@Bi 2 Se 3 nanocomposites. The electrochemical measurements results indicate that the CNTs@C@Bi 2 Se 3 delivers high rate capacity (222 mA h g −1 at 2000 mA g −1 ) and long-term cycle stability (243 mA h g −1 after 300th cycles at 1000 mA g −1 ). Moreover, the electrochemical reaction mechanism is proposed based on the ex situ HRTEM technique. [ABSTRACT FROM AUTHOR]

Transition metal sulfides as anodes for lithium-ion batteries (LIBs) have attracted much attention because of their large Li + storage capacity. However, the lower electrical conductivity and rapid capacity fading during the charge/discharge process strictly prohibit their practical applications. Here, a new strategy is adopted to accommodate the volume change and enhance the electrical conductivity by anchoring Co 1-x S and NiS nanocrystals on amorphous carbon coated multiwalled carbon nanotubes (CNTs). Benefiting from the unique structure, the Co 1-x S and NiS anodes present excellent electrochemical performances including remarkable cyclability and outstanding rate property. Furthermore, the electrochemical reaction process of the anodes is investigated by high-resolution transmission electron microscope and X-ray photoelectron spectroscopy technique. [ABSTRACT FROM AUTHOR]

The SnO 2 quantum dots anchored on amorphous carbon coated multiwalled carbon nanotubes (CNTs@C@SnO 2 ) and SnO 2 quantum dots embedded in amorphous carbon network (SnO 2 @C) have been designed and fabricated by a solvothermal process accompanied by a high temperature calcination treatment. Such unique structured electrodes exhibit excellent cycle stability and high rate capability. At the current density of 5 A g −1 , the capacities of 515 and 364 mAh g −1 are achieved after 300 cycles for CNTs@C@SnO 2 and SnO 2 @C, respectively. [ABSTRACT FROM AUTHOR]

One dimensional CNTs@C@MFe 2 O 4 (M = Ni, Co) composites have been rationally designed and fabricated via a facile solvothermal method and a calcination process. In the unique structure, amorphous carbon served as binder can increase the loading of MFe 2 O 4 on CNTs and strengthened the binding of MFe 2 O 4 and CNTs. As anode materials for lithium ion batteries, the CNTs@C@MFe 2 O 4 delivers a high specific capacity, excellent cycling stability and high rate capacity. The enhanced electrochemical performance can be attributed to the uniform dispersion of MFe 2 O 4 nanoparticles on the amorphous carbon coated CNTs, which can improve contact area between the MFe 2 O 4 nanoparticles and the electrolyte, enhance electrical conductivity, buffer the volume change maintain the structural integrity of the electrodes. Meanwhile, the lithiation and delithiation processes are systematically investigated by X-ray photoelectron spectroscopy analysis and transmission electron microscope technique. Furthermore, the efficient synthesis process developed here can also be extended to design and synthesize other transition metal oxides/carbon nanotube functional materials. [ABSTRACT FROM AUTHOR]

High-efficiency energy materials based on uniform Ag 2 S and Sb 2 S 3 nanoparticles co-sensitization on self-organized TiO 2 nanotube arrays (TiO 2 NTs/Ag 2 S-Sb 2 S 3 ) were prepared by a combination of two-step electrochemical anodization with facile successive ionic layer adsorption and reaction (SILAR) process. Uniform Ag 2 S and Sb 2 S 3 nanoparticles were distributed homogeneously on the surface of TiO 2 NTs. The influences of SILAR deposition cycles of Ag 2 S and Sb 2 S 3 played vital influences on the morphology, visible light response and photoelectrochemical performance of TiO 2 NTs/Ag 2 S-Bi 2 S 3 . The co-sensitization largely enhanced the photoelectrocatalytic removal of Cr(VI) under solar light irradiation. [ABSTRACT FROM AUTHOR]

In this study, we report that the NiFe 2 O 4 /C hollow spheres composed of mesoporous nanospheres have been fabricated through hydrothermal method, calcination treatment and subsequently carbon-coated process. The obtained composite possesses a high surface area (236.44 m 2 g −1 ) and mesopores (2.3 nm), which can efficiently increase the contact area for electrode/electrolyte and buffer the volume change during electrochemical cycling. Combining with the synergistic effect of NiO, Fe 2 O 3 and carbon, the NiFe 2 O 4 /C electrode displays superior electrochemical properties in terms of high reversible capacity, good cycle stability, and excellent rate performance. A specific capacity as high as 1266 mAh g −1 can be obtained after 100 cycles at the current density of 0.2 A g −1 . Even at high current rate of 10 A g −1 , the reversible capacity still remains at 633.3 mAh g −1 after 250 cycles. Therefore, the mesoporous NiFe 2 O 4 /C electrode material may be a promising anode in lithium-ion battery applications. [ABSTRACT FROM AUTHOR]

The mesoporous MnCo 2 O 4 /polypyrrole (PPy) composites have been successfully fabricated through three facile steps, solvothermal synthesis, calcination treatment and subsequent in-situ chemical polymerization. The mesoporous MnCo 2 O 4 /PPy displays good electrochemical performance in terms of high reversible capacity, good rate performance, and excellent stability. The high discharge capacity of 910 mAh g −1 is achieved after 100 cycles at the current density of 200 mA g −1 . The reversible capacity still remains as high as 598 mAh g −1 at the higher current density of 2000 mA g −1 . The improved electrochemical performance is mainly attributed to the mesoporous structure and the coating layer of PPy, which effectively mitigate the volume change and enable good conductivity and thus enhance fast charge transfer. [ABSTRACT FROM AUTHOR]

In this work, hierarchical hydrangea macrophylla like NiCo 2 O 4 has been synthesized by solvothermal method followed by calcination treatment in air. By using Na 2 S as sulfur source, the NiCo 2 O 4 is converted into NiCo 2 S 4 . Such hierarchical NiCo 2 O 4 exhibits a high specific capacity and excellent cycling stability (928 mAh g −1 at a current density of 100 mA g −1 after 100 cycles). Even at high current density of 2000 mA g −1 , the electrode still delivers a specific capacity of 371 mAh g −1 after 50 cycles. When the NiCo 2 S 4 is used as anode materials for lithium-ion batteries, a high discharge capacity of 1204 mAh g −1 can be achieved. Meanwhile, the NiCo 2 S 4 electrode displays good cycling stability and rate capability. The excellent electrochemical performances can be attributed to the unique porous structure, which can effectively reduce the diffusion length for lithium ions and electrons, and alleviate volume expansion during the charge-discharge processes. [ABSTRACT FROM AUTHOR]

Carbon coated flower like Bi 2 S 3 on nickel foam are simply fabricated by a solvothermal synthesis method accompanying with glucose as a precursor of subsequent carbonization. The architectures are directly used as electrodes for electrochemical hydrogen and Li-ion storage. Such architectures display high electrochemical hydrogen storage and the discharging capacity of 165 mAh g −1 is obtained. When used as anode material, the binder free Bi 2 S 3 @C/Ni electrode delivers superior cycling stability and rate capability. Discharge capacity reaches as high as 698 mAh g −1 after 50 cycles at a current density of 100 mA g −1 . Even at 1000 mA g −1 , the capacity still remains at 510 mAh g −1 after 40 cycles. The superior performance can be ascribed to the unique electrode. The porous electrode gives more reaction sites and accommodates volume change during cycling; while the carbon shell improves electronic conductivity and suppresses particle aggregation. [ABSTRACT FROM AUTHOR]

Abstract: Hierarchical Bi2S3 hollow spheres have been synthesized by a facile solvothermal process in the presence of sodium tartrate. The hollow spheres are composed of numerous ultrathin nanorods with the average diameter of 15 nm. Based on the time dependent electron microscope observations, the formation mechanism of such hierarchical structures has been proposed as a sodium tartrate directed self-assembled process and oriented attachement mechanism. The morphology and size of the subunits can be controlled by adjusting the amount of sodium tartrate. The Nitrogen adsorption-desorption measurements suggest that mesopores exist in these hollow spheres. The as-derived Bi2S3 hollow spheres exhibit excellent electrochemical hydrogen storage properties. [Copyright &y& Elsevier]

Highlights: [•] The sulfur doped Sb2Se3 nanosheets are synthesized. [•] The anisotropic growth process and Ostwald ripening mechanism are proposed. [•] The sulfur doped Sb2Se3 nanosheets show higher electrochemical properties. [ABSTRACT FROM AUTHOR]