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Precursors of ammonium vanadium bronze (NH4V4O10) nanowires assembled on a conductive substrate were prepared by a hydrothermal method. After calcination at 360°C, the NH4V4O10 precursor transformed to vanadium pentoxide (V2O5) nanowires, which presented a high initial capacity of 135.0mA h g(-1) at a current density of 50mA g(-1) in 5M LiNO3 aqueous solution; while the specific capacity faded quickly over 50 cycles. By coating the surface of V2O5 nanowires with water-insoluble polypyrrole (PPy), the formed nanocomposite electrode exhibited a specific discharge capacity of 89.9mA h g(-1) at 50mA g(-1) (after 100 cycles). A V2O5@PPy //LiMn2O4 rechargeable lithium battery exhibited an initial discharge capacity of 95.2mA h g(-1); and after 100 cycles, a specific discharge capacity of 81.5mA h g(-1) could retain at 100mA g(-1)., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Polyaniline (PANI) nanowire arrays have been prepared for the first time using Na5V12O32 nanowires as a sacrificial template. Fourier-transformed infrared spectroscopy and energy-dispersive X-ray spectroscopy were used to characterize the as-prepared PANI nanowire arrays. Further, the electrochemical properties of the PANI nanowire arrays for lithium-ion batteries were investigated with cyclic voltammetry, galvanostatic charge-discharge experiment, and rate performance. It delivered a high discharge capacity of 119.79 mA h g−1 after 100 cycles between 2.0 and 4.0 V at 30 mA g−1. [ABSTRACT FROM AUTHOR]

With a theoretically high capacity and suitable discharge/charge plateaus, lithium vanadates (such as Li 0.04 V 2 O 5 ) can be used as cathode material for lithium ion batteries. Herein, Li 0.04 V 2 O 5 nanowires are densely anchored onto reduced graphene oxide (rGO) nanosheets to form a Li 0.04 V 2 O 5 @rGO nanocomposite by a hydrothermal method with subsequent thermal treatment. Due to this unique structure, the Li 0.04 V 2 O 5 @rGO exhibits remarkable rate performance and excellent cycling stability. Specifically, it delivers a reversible discharge capacity of 738.09 mA h g −1 at a current density of 100 mA g −1 in the voltage range of 2.0–4.0 V. After 500 cycles, it still maintains a high capacity of 731.70 mA h g −1 , which represents 95.01% retention of the original reversible capacity. These results indicate that the Li 0.04 V 2 O 5 @rGO could be a promising candidate as cathode active material for long-term cycling performance in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Iron vanadate nanowires were firstly synthesized by a cation-exchange routine. • Well-dispersed porous iron vanadate nanowires firmly anchored on Ti foil. • The iron vanadate nanowires exhibit superior lithium storage capability. • The charge-discharge process prefers to pseudocapacitive-controlled behavior. Abstract The nanostructuring of materials can solve the problem of low conductivity of the vanadate electrode, thereby increasing the potential for lithium storage performance. The traditional battery is prepared by coating active materials on current collector, which produces large contact resistance between the current collector and the electrodes, impeding the overall electrochemical performances of the battery. In this work, we propose and verify a scheme for directly loading porous iron vanadate nanowire array electrode on titanium foil. The resultant electrode (the as-prepared iron vanadate annealed at 300 °C) exhibits an enhanced lithium storage performance, the discharge capacity after 100 cycles is 1041.10 mAh·g−1 at a current density of 300 mA·g−1. The iron vanadate nanowire electrode is fabricated by a simple and scalable cation-exchange method, which can be provided for the separate and integrated large-scale industrialization of vanadate electrode materials. [ABSTRACT FROM AUTHOR]

Lithium vanadate nanowires have been electrodeposited onto a titanium (Ti) foil by a direct current electrodeposition without template. The morphology, crystal structure, and the effects of deposition voltage, temperature and time on the prepared samples were tested and presented. The as-prepared lithium vanadate nanowires/Ti composite can be used as electrode for lithium-ion battery. Electrochemical measurements showed that the electrode displayed a specific discharge capacitance as high as 235.1 mAh g −1 after 100 cycles at a current density of 30 mA g −1 . This research provides a new pathway to explore high tap density vanadates nanowires on metals with enhanced electrochemical performance. [ABSTRACT FROM AUTHOR]

This paper reports a study on the electrochemical performance of vanadium trioxide (V 2 O 3 ) nanowire arrays as a cathode material for Li-ion battery. V 2 O 3 nanowire arrays are formed via thermal treatment of ammonium vanadium bronze (NH 4 V 4 O 10 ) nanowires in a 5% H 2 and 95% Ar atmosphere. X-ray diffraction confirms the thermal reduction. The V 2 O 3 nanowire arrays as an electrode of lithium-ion battery exhibit high reversible capacity and excellent long-term cycling stability. The discharge capacity increases from 243 to 428 mA h g −1 at the first 20 cycles. After 100 cycles, a stable capacity of 444 mA h g −1 is retained at a current density of 30 mA g −1 . [ABSTRACT FROM AUTHOR]

Design and fabrication of novel optimized electrode materials are important for the development of new batteries for energy storage applications. Herein, we report on a hierarchical bulk electrode material with a tailored nanostructure that which consists of three components: a NH 4 V 4 O 10 nanowire as an active skeleton, an intermediate polymer layer (polypyrrole, PPy), and a metal oxide layer (MnO 2 ) as the outside shell. The NH 4 V 4 O 10 -PPy-MnO 2 nanowires exhibit present higher capacitance than that of the simple NH 4 V 4 O 10 -PPy core@shell or NH 4 V 4 O 10 nanowires. The structure of double shells of combined PPy and MnO 2 is a key factor in enhancing their electrochemical performance including high specific capacitance and excellent cycling stability. Our V-based core@shell@shell structure can serve as freestanding, compressible electrodes for various energy devices. [ABSTRACT FROM AUTHOR]

Use of hybridized transition-metal oxides nanostructures with a shell coating show promise for improving the electrochemical performance of sodium-ion batteries. Herein, a novel type of designed sodium vanadate @ polypyrrole (Na 5 V 12 O 32 @PPy) nanocomposites with a synergetic core-shell structure was fabricated using sequential hydrothermal and electrodeposition methods. When the Na 5 V 12 O 32 @PPy nanocomposites were employed as a cathode, the assembled sodium-ion batteries exhibited a high reversible discharge capacity of 213 mAh g −1 at a current density of 30 mA g −1 , high rate performance (133 mAh g −1 at 480 mA g −1 ) and superior cycling performance (202 mAh g −1 at 100 mA g −1 after 100 cycles with a capacity retention of 94%). By contrast, the cycling behavior of this novel material proved to be much better than the naked Na 5 V 12 O 32 nanowires. This research provides a new pathway to explore cathode materials for sodium-ion battery with enhanced electrochemical performance. [ABSTRACT FROM AUTHOR]

Ammonium vanadate (NH 4 V 4 O 10 ) nanowire flowers and nanowires on titanium (Ti) foils are synthesized by hexamethylenetetramine (HMTA)-assisted hydrothermal reactions as a cathode material for lithium-ion battery. The as-prepared NH 4 V 4 O 10 nanowires are about 50 nm in diameter and several micrometers in length. The effects of reaction time, temperature and additive concentration on the resulting morphology are investigated. Reversible lithium intercalation behavior of the nanowires has been evaluated by cyclic voltammetry and galvanostatic discharge–charge cycling. The NH 4 V 4 O 10 nanowires on Ti foil deliver a high discharge capacity of 168.5 mA h g −1 after 100 cycles between 2.0 and 4.0 V at 50 mA g −1 . A high rate capability is obtained with a remaining discharge capacity of about 182.6 mA h g −1 after 35 cycles at various rates. Further, the NH 4 V 4 O 10 nanowires on Ti foil have a higher discharge capacity of 330.5 mA h g −1 after 100 cycles at 0.8–4.0 V at 50 mA g −1 . [ABSTRACT FROM AUTHOR]

BiVO 4 nanowire array is fabricated by a hydrothermal method, and the nanowire array and a lithium foil are used as working and counter electrodes, respectively, to assemble a lithium-ion battery. After charging to 4 V, the BiVO 4 nanowire array has a strong oxidizing property. The pyrrole can be in-situ polymerized on the surface of the charged BiVO 4 nanowire array to form a polypyrrole coating layer in pyrrole solution. The morphology and structure properties of the samples are characterized and analyzed in detail. The lithium storage performances of the samples are also measured and compared. The obtained BiVO 4 -PPy nanowires have stable cycle performance and a discharge capacity of more than 400 mAh g−1 after 50 cycles. This work provides a new method for synthesizing conductive polymers on charged electrodes. • A novel in-situ coating polypyrrole (PPy) on charged BiVO 4 nanowires method is used to improve the cycle performance of the electrode. • The obtained BiVO 4 -PPy nanowires have a capacity of more than 400 mAh g−1 at a current density of 100 mA g−1 after 50 cycles in 1–4 V. [ABSTRACT FROM AUTHOR]