Jane Yao

Characterization of Nanocrystalline Si-MCMB Composite Anode Materials

Nanocrystalline Si-mesocarbon microbeads (MCMB) composite anode materials were prepared by ballmilling. Scanning electron microscopic observation showed that the spherical shape of MCMB particles can be retained via moderate ballmilling. Ballmilling conditions have an impact on the capacity and cyclability of nanocrystalline Si-MCMB composites. The optimized Si-MCMB composite anode demonstrated a reversible capacity of 1066 mAh/g with good cyclability. A reaction model has been proposed to explain the reaction mechanisms of lithium insertion and extraction in the Si-MCMB electrode.

Characterization of LiMxFe1–xPO4 (M = Mg, Zr, Ti) Cathode Materials Prepared by the Sol-Gel Method

A series of LiM x Fe 1 - x PO 4 (M = Mg,Zr,Ti) phosphates were synthesized via a sol-gel method. Transmission electron microscopy observations show that LiM x Fe 1 - x PO 4 particles consist of nanosize crystals, ranging from40 to 150 nm. High-resolution TEM analysis reveals that a layer of amorphous carbon was coated on the surface of the LiM x Fe 1 - x PO 4 particles, which substantially increases the electronic conductivity of LiM x Fe 1 - x PO 4 electrodes. The doped LiM x Fe 1 - x PO 4 powders are phase pure. Near full capacity (170 mAh/g) was achieved at the C/8 rate at room temperature for LiM x Fe 1 - x PO 4 electrodes. The doped LiM x Fe 1 - x PO 4 electrodes demonstrated better electrochemical performance than that of undoped LiFePO 4 at high rate.

Tungsten Disulfide Nanotubes for Lithium Storage

WS 2 nanotubes were synthesized by sintering amorphous WS 3 at high temperature under flowing hydrogen. High-resolution transmission electron microscopy observation revealed that the as-prepared WS 2 nanotubes have an open end with an inner hollow core of about 4.6 nm. We studied the lithium intercalation behavior of WS 2 nanotubes. The WS 2 nanotubes demonstrated a stable cyclability in a wide voltage range (0.1-3.1 V vs. Li/Li + ). The nanotubes could provide a new class of electrode materials for lithium-ion batteries.

Nanosize cobalt oxides as anode materials for lithium-ion batteries

Nanosize cobalt oxides (Co3O4) were synthesised by chemical decomposition of cobalt octacarbonyl in toluene at low temperature. Electrochemical properties of as-prepared Co3O4 as anodes in Li-ion cells were tested. The nanosized Co3O4 electrode demonstrate a stable reversible lithium storage capacity of 360 mAh/g within 30 cycles. The reactivity of as-prepared Co3O4 in Li-ion cells could be attributed to nanosize particles of Co3O4 and its lithiation products.

Tin-based composite materials as anode materials for Li-ion batteries

Abstract Tin, tin oxide and NiSn-based nanocomposites with Al2O3 dispersion were prepared by ball milling to see their electrochemical properties as a new anode material for lithium-ion batteries. Electrochemical tests demonstrated that the initial charge–discharge capacities are very high for these materials. However, the capacity faded rapidly after the first cycle due to irreversible reactions. This is thought to be caused by the separation of the active materials from the inert oxide particles. The initial cycling efficiency was markedly improved by subsequent annealing of the ball-milled electrode.

Growth and lithium storage properties of vertically aligned carbon nanotubes

High-purity vertically aligned carbon nanotubes (CNTs) were prepared on a quartz substrate by thermal chemical vapour deposition (CVD). The as-prepared carbon nanotubes have an outer diameter of 40–60 nm and a length of 70–80 μm. HRTEM observation revealed that there were compartment structures in the carbon nanotubes. The vertically aligned CNTs exhibit a high reversible lithium storage capacity of 950 mAh/g in lithium-ion cells.

Li Storage Properties of Carbon Nanotubes Prepared by Chemical Vapour Deposition

Abstarct: Multiwalled carbon nanotubes were prepared using chemical vapor de sition (CVD). The morphology and microstructure of carbon nanotubes were observed by HRTE M. he asprepared carbon nanotubes are entangled to bundles with a diameter of s everal tens nanometers. Electrochemical properties of carbon nanotubes as anodes in lithiumion batteries were investigated via a variety of electrochemical testing techniques. The car bon nanotube electrode demonstrated a reversible lithium storage capacity of 340 mAh/g with good cyclabilit y at moderate current density. The kinetic properties of lithium insertion in carbon nanotube electrodes were characterised via a.c. impedance measurements.