We have fabricated self-assembled LiNi1/3Co1/3Mn1/3O2 nanosheets via a facile synthesis method combining coprecipitation with the hydrothermal method. Scanning electron microscopic images show that the self-assembly processes for the LiNi1/3Co1/3Mn1/3O2 nanosheets depend on the reaction time and temperature. The nanosheet structure is uniform, and the width and thickness of the nanosheets are in the ranges of 0.7–1.5 μm and 10–100 nm, respectively. As a cathode material, the as-synthesized LiNi1/3Co1/3Mn1/3O2 nanosheets have demonstrated outstanding electrochemical performance. The initial specific capacity was 193 mAh g–1, and the capacity was maintained at 189 mAh g–1 after 100 cycles at 0.2 C, and 155 mAh g–1 at 1 C (after 1000 cycles). The LiNi1/3Co1/3Mn1/3O2 nanosheets have efficient contact with the electrolyte and short Li+ diffusion paths, as well as sufficient void spaces to accommodate large volume variation. The nanosheets are thus beneficial to the diffusion of Li+ in the electrode. The enhanced electrical conductance and excellent capacity demonstrate the great potential of LiNi1/3Co1/3Mn1/3O2 nanosheets for energy storage applications.Keywords: cathode material; LiNi1/3Co1/3Mn1/3O2; lithium-ion batteries; nanosheets; self-assembled;

•A hydrothermal method is used to synthesize FeVO4·xH2O/graphene nanorods.•The graphene could improve conductivity and lithium ion diffusion rate.•FeVO4·xH2O/graphene composite exhibits outstanding electrochemical performance.A simple hydrothermal route was used to synthesize FeVO4·xH2O and FeVO4·xH2O/graphene nanorods. Their structures and morphologies were characterized by x-ray diffraction analysis (XRD), scanning electronic microscopy (SEM) and transmission electron microscopy (TEM). The content of graphene in composite was about 20%. The discharge capacities of FeVO4·xH2O and FeVO4·xH2O/graphene were 455.4 mA h g−1 and 1407.8 mA h g−1 after 100 cycles at the current density of 100 mA g−1 in the voltage range of 0.01–3 V, which showed that FeVO4·xH2O/graphene composite would be a promising anode material.

FeVO4@TiO2 nanocomposite was fabricated via a simple and cost-effective approach. The FeVO4 nanorods were synthesized by a hydrothermal method combined with calcination route without using any template and then coated with TiO2 through an annealing process of dihydroxybis titanium. The FeVO4 nanocomposite has a significantly enhanced electrochemical performance by coating with TiO2. The FeVO4@TiO2 delivered a specific capacity of 1147 mAh g−1, the discharge capacity remaining at 596 mAh g−1 after 100 cycles (at 200 mA g−1), which is higher than that of pure FeVO4. The discharge capacity of FeVO4@TiO2 could be as high as 337 mAh g−1 (at a high load current density of 10,000 mA g−1). Compared with pure FeVO4, FeVO4@TiO2 shows a better rate performance. The amorphous TiO2 coating on a layer of FeVO4 created efficient improved stability of the structure during the charge/discharge process. The excellent rate capability and cyclic stability of the sample proved that FeVO4@TiO2 could be used as a new anode for lithium ion battery application. The synthesis method can also be applied to synthesize other related materials with typical morphologies and properties.

The molybdenum disulfide/carbon (MoS2/C) microsphere composite is synthesized by a facial hydrothermal method using carbon spheres as a template. The structure and morphology of the expected compounds are characterized by x-ray diffraction, x-ray photoelectron spectroscopy and scanning electron microscopy techniques. The electrochemical properties of the composite are investigated by a battery testing system. The as-prepared MoS2/C composite has an initial discharge capacity of 943 mAh g−1 and retained a reversible capacity at 705 mAh g−1 after 165 cycles with nearly 100% coulombic efficiency, exhibiting better electrochemical performances than those of pure MoS2. The MoS2/C composite is a promising anode material for lithium-ion battery applications.

The surface of layered LiNi1/3Co1/3Mn1/3O2 was coated with AlPO4 by co-precipitation method and followed by heat treatment. The prepared samples were characterized by XRD and SEM. The samples coated with AlPO4 exhibited both improved rate and cycle capacity compared with the pristine LiNi1/3Co1/3Mn1/3O2. Especially, the sample coated with 1 wt% AlPO4 showed outstanding cyclability. The electrochemical impedance spectroscopy (EIS) results indicated that the AlPO4 coating layer significantly suppressed the increase of charge-transfer resistance (Rct). The activation energy of the charge transfer processes at the electrode/electrolyte interface was reduced by AlPO4 coating. These results indicate that AlPO4 coated LiNi1/3Co1/3Mn1/3O2 could be a promising cathode material for lithium ion batteries.

•The precursors of ZnMn2O4 microspheres are synthesized by a mixed solvothermal method.•The morphology of expected compound is depended on different precipitants.•The ZnMn2O4 synthesized by the typical method exhibits excellent electrochemical properties.The precursors of ZnMn2O4 microspheres are synthesized by a mixed solvothermal method using ZnAc2·2H2O and MnAc2·4H2O as metal source as well as urea or ammonium bicarbonate as the precipitant. The as-synthesized precursors are further heat-treated at a suitable temperature to obtain the expected compounds. The expected samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The electrochemical properties of the sample are investigated by battery testing system. The influences of different precipitants on its structure, morphology and the electrochemical properties are discussed. The results show that the morphology of expected compound is depended on different precipitants. When tested as anode material for lithium ion battery, the ZnMn2O4 sample obtained by pyrolysis of the Zn0.33Mn0.67CO3 precursor using ammonium bicarbonate as precipitant exhibits better electrochemical properties. It has a high initial discharge specific capacity of 1269 mAhg−1 and remains its capacity at 602 mAhg−1 after 100 cycles under a constant current of 100 mAg−1 in the voltage range of 0.01–3 V. The outstanding electrochemical performances for the ZnMn2O4 microspheres suggest that it could be a promising candidate as a novel anode material for lithium ion battery applications.Download high-res image (223KB)Download full-size imageThe ZnMn2O4 sample obtained by pyrolysis of the Zn0.33Mn0.67CO3 precursor using ammonium bicarbonate as precipitant exhibits a better electrochemical properties. It has a high initial discharge specific capacity of 1269 mAhg−1 and remains its capacity at 602 mAhg−1 after 100 cycles under a constant current of 100 mAg−1 in the voltage range of 0.01–3 V.

•FeCO3 samples (FCO-1 and FCO-2) with different morphologies are successfully synthesized by a mixed solvothermal route.•FCO-2 exhibits better electrochemical properties than those of FCO-1.•FCO-2 delivers an initial discharge capacity of 1518.09 mAh g−1 and remains capacity as 1019.47 mAh g−1 after 100 cycles.FeCO3 with the morphology of microspheres and rice-like were successfully fabricated by a facile mixed solvothermal method by using urea and ammonium bicarbonate as precipitants, respectively. The as-synthesized samples were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The electrochemical properties of the samples were investigated by battery testing system. The influences of different precipitants on its structure, morphology and the electrochemical properties were also discussed. The results showed that the diameter of FeCO3 microspheres (FCO-1) was 8–10 μm by using urea as precipitant, while the size of FeCO3 rice-like (FCO-2) by using ammonium bicarbonate as precipitant was 0.5–1.0 μm. When used as an anode material for lithium ion batteries, FCO-1 and FCO-2 delivered the initial specific discharge capacities of 1563.54 and 1518.09 mAh g−1 at the current density of 100 mA g−1 in the voltage range of 0.01–3 V and remained its reversible value of 854.65 and 1019.47 mAh g−1 over 100 cycles, respectively. The FCO-2 still possessed a considerable capacity of 890.23 mAh g−1 at a high current density of 500 mA g−1. Therefore, FCO-2 synthesized through using ammonium bicarbonate as precipitant could be a potential anode candidate for lithium ion batteries.FeCO3 samples (FCO-1 and FCO-2) were successfully fabricated through a facile mixed solvothermal method. They delivered the initial specific discharge capacities of 1563.54 and 1518.09 mAh g−1 at the current density of 100 mA g−1 in the voltage range of 0.01–3 V. FCO-2 behaved much better electrochemical performances than those of FCO-1.Download high-res image (248KB)Download full-size image

•A high performance ORR catalyst of Pt/SnO2/C nanofiber was fabricated.•The catalyst exhibits competitive ORR catalytic activity compared to the Pt/C catalyst.•The catalyst displays enhanced methanol tolerance and superior durability.•The mechanism of enhanced ORR catalytic activity was explored.•It provides a guideline for designing analogous structure ORR catalyst.In this report, an efficient oxygen reduction reaction (ORR) electrocatalyst of platinum (Pt) decorated SnO2/C (Pt/SnO2/C) nanofiber was fabricated by using a Pt galvanic displacement of a copper (Cu) layer electrodeposited on electrospinning SnO2/C nanofiber. Microscopic and spectroscopic characterizations revealed that the facile electrospinning and galvanic displacement route generated numerous dispersed Pt nanoparticles on the SnO2/C nanofiber; and Pt nanoparticles (d ~ 2–3 nm) with high composition of Pt (111) facet were preferably deposited at the SnO2/C junctions to form triple junction nanostructures. The resulting Pt/SnO2/C nanocomposite presented an onset potential of 0.02 V vs RHE, specific activity of 1.12 mA cm− 2 and mass activity of 615 mA/mgPt at − 0.05 V vs RHE. It is competitive to commercial Pt/C (10 wt% Pt) catalyst toward ORR. Notably, in comparison with commercial Pt/C, the composition displayed superior electrochemical durability and enhanced methanol tolerance. It was demonstrated that the presence of Pt/SnO2/C triple junction nanostructures coupled with high composition of Pt (111) facets synergistically contributed the enhanced ORR activity, while the good conductivity of the C facilitates the electron transfer during the ORR process. The metal-metal oxide-carbonaceous heterogeneous structure represents a promising platform for designing ORR catalysts with high performance.

ZnCo2O4 was synthesized through the rheological phase reaction method using zinc acetate dehydrate, cobalt (II) acetate tetrahydrate, and citric acid as raw materials. The precursors were heat-treated in a muffle furnace at 400 °C or 500 °C, respectively. The samples were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The electrochemical properties of the samples were investigated. The results show that ZnCo2O4 nanoparticles were synthesized successfully. The particles took on irregular quasi-spherical shapes, and the sizes of the particles were less than 100 nm. The electrochemical properties showed that the ZnCo2O4 synthesized at 400 °C featured better reversible capacity than that of ZnCo2O4 synthesized at 500 °C, and its specific capacity was 801 mAh g−1 after 100 cycles at a constant current of 100 mAh g−1 in the voltage range of 0.01–3 V. Hence, the ZnCo2O4 synthesized by this method could be a promising anode material for lithium ion battery application.

Three-dimensional (3D) Fe2(MoO4)3 microspheres with ultrathin nanosheet constituents are first synthesized as anode materials for the lithium-ion battery. It is interesting that the single-crystalline nanosheets allow rapid electron/ion transport on the inside, and the high porosity ensures fast diffusion of liquid electrolyte in energy storage applications. The electrochemical properties of Fe2(MoO4)3 as anode demonstrates that 3D Fe2(MoO4)3 microspheres deliver an initial capacity of 1855 mAh/g at a current density of 100 mA/g. Particularly, when the current density is increased to 800 mA/g, the reversible capacity of Fe2(MoO4)3 anode still arrived at 456 mAh/g over 50 cycles. The large and reversible capacities and stable charge–discharge cycling performance indicate that Fe2(MoO4)3 is a promising anode material for lithium battery applications.

•A VOx/C composite synthesized by electrospinning method takes on morphology of nanofiber.•The VOx/C composite mainly consists of VO2 and V2O5 and carbon.•The VOx/C composite had high reversible specific capacity as an anode material.•The VOx/C composite behaved higher rate capacity and excellent cycle performance.A VOx/C nanofiber composite has been synthesized by using the electrospinning method and studied as an anode material for lithium ion batteries. The VOx/C nanofibers mainly are composed of VO2, V2O5, and carbon. The VOx/C nanofibers exhibited excellent electrochemical performance. A high discharge capacity of 850 mA h g−1 can be retained after 100 cycles at the current density of 40 mA g−1. A discharge capacity of 550 mA h g−1 still can be delivered after 100 cycles, when the current density is increased to 1000 mA g−1.

A nano-MoO3/C composite was synthesized using the electrospinning method. Thermal analysis was used to determine the carbon content in the composite. The MoO3/C composite was characterized by X-ray diffraction, and the particle size and shape of the MoO3/C composite were observed by scanning and transmission electron microscopy. The results showed that the MoO3/C composite takes on the morphology of nanofibers, with the diameters of the nanofibers ranging from 50 to 200 nm. The nanofibers are composed of amorphous nano-MoO3 and carbon, with the carbon content in the composite about 42% and the MoO3 content about 58%. The electrochemical properties of the MoO3/C composite were also investigated. The MoO3/C composite nanofiber electrodes exhibited both high reversible capacity and good cycling performance when cycled at room temperature in a 3.0–0.01 V potential (vs Li/Li+) window at current density of 40 mA g−1. The MoO3/C composite retained a discharge capacity of 710 mAh g−1 after 100 cycles. When the load current density was increased to 800 mA g−1, the MoO3/C composite still retained a discharge capacity of 300 mAh g−1 after 100 cycles. The reasons for the outstanding electrochemical properties of the MoO3/C composite are also discussed.

•Fe3O4 particles are encapsulated by HKUST-1 to form core-shell microspheres composite.•The composite exhibits outstanding electrochemical performances as a novel anode.•The typical approach can be used to prepare some novel electrode materials.The Fe3O4@MOF composite with a microspheric core and a porous metal-organic framework (MOF HKUST-1) shell has been successfully synthesized utilizing a versatile Layer-by-Layer (LBL) assembly method. The structure was identified by X-ray diffraction (XRD), and the morphology was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The Fe3O4@MOF composite exhibited outstanding electrochemical properties when it was used as an anode material for lithium ion batteries (LIBs). After 100 discharge-charge cycles at a current density of 100 mA g−1, the reversible capacity of Fe3O4@MOF could maintain ∼1002 mAh g−1, which was much higher than that of the bare Fe3O4 counterpart (696 mAh g−1). Moreover, load the current density as high as 2 A g−1 (after 70 cycles at the current density step increased from 0.1 to 2 A g−1), it still delivered a reversible capacity of ∼429 mAh g−1. The results demonstrate that the cycling stability of Fe3O4 as an anode could be significantly improved by coating Cu3(1,3,5-benzenetricarboxylate)2 (HKUST-1). This strategy may offer new route to prepare other composite materials using different particles and suitable Metal-organic frameworks (MOFs) for LIBs application.Fe3O4@MOF core-shell microspheres were successfully synthesized using a versatile Layer-by-Layer (LBL) assembly method and investigated as an anode material for the first time. The composite exhibited high reversible capacity and excellent rate performances as anode material.