X.B. Zhao

Nickel Foam-Supported Porous NiO ∕ Ag Film Electrode for Lithium-Ion Batteries

Porous NiO film was deposited on a nickel foam substrate by a chemical bath deposition technique at room temperature, and the NiO/Ag film was prepared by loading the NiO film with Ag nanoparticles. The NiO/Ag film with a thickness of about 1 μm is constructed by NiO nanoflakes, in which the Ag nanoparticles with sizes of about 5 nm are highly dispersed. As an anode for lithium-ion batteries, its initial coulombic efficiency is as high as 70%. The discharge-charge curve and cyclic voltammograms show that the NiO/Ag film electrode exhibits smaller potential hysteresis and weaker polarization as compared to the NiO film electrode. The specific capacity after 50 cycles for the NiO/Ag film is 550 mAh g -1 at 0.5 A g -1 , 450 mAh g -1 at 1.5 A g -1 , and 420 mAh g -1 at 3 A g -1 , higher than that of NiO (490 mAh g -1 at 0.5 A g -1 , 350 mAh g -1 at 1.5 A g -1 , and 300 mAh g -1 at 3 A g -1 ). The improvement of these electrochemical properties is attributed to the Ag nanoparticles, which enhanced the electrical conduction of the electrode.

Self-assembly of hierarchical Fe3O4 microsphere/graphene nanosheet composite: towards a promising high-performance anode for Li-ion batteries

A hierarchical Fe3O4 microsphere/graphene nanosheet (H-Fe3O4-MS/GNS) composite has been synthesized by a facile one-pot solvothermal route. The Fe3O4 microspheres uniformly decorated the surface of the two dimensional GNS. Each Fe3O4 microsphere possesses a hierarchical and porous structure, which is composed of Fe3O4 nanoparticles with a diameter of about 10 nm. As an anode material for Li-ion batteries, the H-Fe3O4-MS/GNS composite shows high specific capacity and good cycling stability (1171.6 mA h g−1 at 200 mA g−1 and 940.4 mA h g−1 at 500 mA g−1 up to 70 cycles), reduced voltage hysteresis, as well as enhanced rate capability. The improved electrochemical performance can be attributed to the combination of the conductivity, confinement and dispersion effects of GNS and the porous hierarchical structure of the Fe3O4 microsphere.

A study of Zn4Sb3 as a negative electrode for secondary lithium cells

Abstract Antimony zinc alloy, Zn 4 Sb 3 , was studied as a potential material for negative electrodes of lithium-ion batteries. It was found that the reversible capacity of ball-milled Zn 4 Sb 3 in the first cycle reached 507 mA h g −1 and increased up to 580 mA h g −1 when the alloy was ball-milled with about 11.8 wt.% graphite additives. Ex-situ XRD analyses of the pure Zn 4 Sb 3 electrodes during cycling showed that several lithium-containing compounds such as LiZnSb, Li 3 Sb and LiZn have been formed successively during the insertion of lithium into Zn 4 Sb 3 . It was found that the ball-milled composite, Zn 4 Sb 3 /C 7 , possesses high initial reversible capacity, small voltage hysteresis and good capacity retention, which make this material an interesting potential electrode for lithium-ion batteries.

Transport properties of β-Zn4Sb3 prepared by vacuum melting

Abstract In this paper, single-phase polycrystalline β-Zn 4 Sb 3 samples were prepared by vacuum melting, and subjected to characterization using X-ray diffraction. The transport properties of the samples were measured between room temperature and 723 K. The power factor was found to be high between 500 and 650 K, and a maximum value of 3.9×10 −4 W m −1 K −2 was obtained at 623 K. The result suggested that this relatively inexpensive material is very promising for thermoelectric applications.

Sulfur@hollow polypyrrole sphere nanocomposites for rechargeable Li–S batteries

Homogeneously dispersed sulfur in hollow polypyrrole spheres composites, which serve to improve the electric conductivity and provide flexible matrix, were synthesized on a large scale.

Electrochemical properties of some Sb or Te based alloys for candidate anode materials of lithium-ion batteries

Some antimony or tellurium based thermoelectric alloys have been prepared and studied as new candidate anode materials for lithium-ion batteries. It was found that some thermoelectric antimonides yield a volume capacity for reversible lithium storage more than twice that of state of the art carbon based materials. Ex-situ XRD analyses show that the semimetals such as antimony, bismuth and tellurium in the semiconducting thermoelectric alloys are the active elements for the lithium adsorption. However, inactive elements are also necessary for an alloy electrode to ensure the electrochemical capacity retention during cycling.

Thermoelectric properties of Bi0.5Sb1.5Te3/polyaniline hybrids prepared by mechanical blending

Abstract Thermoelectric hybrid materials consisting of Bi0.5Sb1.5Te3 and 1–7 wt.% polyaniline (PAn) have been prepared by mechanical blending and cold pressing. It is found that the Seebeck coefficients of the hybrid materials are about 10% lower than the Bi0.5Sb1.5Te3 sample. It is shown that the power factors of the hybrid materials decrease significantly with the increase of the polymer content due to mainly the decline of electric conductivities.

Design and synthesis of NiO nanoflakes/graphene nanocomposite as high performance electrodes of pseudocapacitor

In this contribution, nickel oxide (NiO) nanoflakes/graphene (NiO/G) nanocomposites have been prepared by a simple hydrothermal method followed by a thermal treatment with N2 gas. NiO nanoflakes (∼30–80 nm in diameter) are uniformly anchored on graphene sheets in a layer-by-layer form, which effectively prevents the aggregation of NiO nanoflakes and offers two-dimensional (2D) diffusion channels for the transportation of electrons and ions. Compared to bare NiO nanoflakes, the NiO/G composite electrode exhibits improved electrochemical properties. The specific capacitances of the NiO/G electrode are 240 F g−1 at 5 A g−1 and 220 F g−1 at 10 A g−1, which are much higher than those of the NiO electrode (i.e., 100 F g−1 at 5 A g−1 and 90 F g−1 at 10 A g−1). In addition, the synergistic effect from this hybrid structure has led to the significantly improved cycling stability of the NiO/G supercapacitor, which exhibits a superior cycling stability of 100–120% retention of specific capacitance after 1500 cycles. This approach may advance the design and implementation of hybrid nanostructures in high-performance reversible supercapacitors.

Facile synthesis of C–Fe3O4–C core–shell nanotubes by a self-templating route and the application as a high-performance anode for Li-ion batteries

In this study, we synthesized C–Fe3O4–C core–shell nanotubes through a facile chemical vapor deposition (CVD) method using Fe2O3 nanotubes as the self-templates. The hydrothermal product α-Fe2O3 hematite exhibits a tubular structure with an inner diameter of 70–100 nm, a wall thickness of 10–20 nm, and a length of 300–800 nm. After the CVD reaction in C2H2, α-Fe2O3 could be transformed into C–Fe3O4–C with the tubular structure reserved. The tubular C–Fe3O4–C is constructed by an Fe3O4 nanotube core and 5 nm thick carbon shells on both inner and outer surfaces of the Fe3O4 nanotube. The C–Fe3O4–C nanotube anode exhibits a stable cycling with a capacity over 700 mA h g−1 retained after 120 cycles at 100 mA g−1. The improved electrochemical properties of C–Fe3O4–C nanotubes compared with bare α-Fe2O3 could be attributed to the introduction of the carbon shells, which not only supplya high conductive channel and buffer matrix, but also keep the structural stability of the Fe3O4 nanotube upon cycling.

Electrochemical lithiation and delithiation of FeSb2 anodes for lithium-ion batteries

Abstract Iron antimonide, FeSb 2 , has been prepared by levitation melting. The electrochemical cycling behaviors of FeSb 2 were evaluated using lithium-ion model cell Li/LiPF 6 (EC+DMC)/FeSb 2 . It was found that the reversible capacity of FeSb 2 in the first cycle reached 507 mA h g −1 , and a reversible capacity of about 282 mA h g −1 was still maintained after 15 cycles. In our present work, we also found that the FeSb 2 /mesocarbon microbeads (MCMB) composite material possessed higher initial reversible capacity and better cycle life than pure FeSb 2 , which made it suitable for use as anode material in rechargeable lithium-ion batteries.