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Abstract: Carbon coated lithium iron phosphates were prepared by a carbon aerogel synthesis process, through which LiFePO4 particles were embedded in amorphous carbon. The carbon coating effect can significantly enhance the electronic conductivity of LiFePO4. The electrochemical properties of the as-prepared LiFePO4 cathode materials were systematically characterised. The carbon coated LiFePO4 cathode demonstrated a high capacity and stable cyclability. [Copyright &y& Elsevier]

Abstract: Nanosize silver and tin dioxide powders were synthesised by a novel reverse micelle technique. The reverse micelles were formed from a microemulsion of organic solvents, water based salts and surfactants. The spherical nanosize Ag powders were formed via in situ reduction. The tin hydroxide precipitates were formed in reverse micelles and converted to tin dioxide nanopowders after heat treatment. The Ag and SnO2 powders have a particle size in the range of 20–50nm. The as-prepared nanosize Ag and SnO2 nanopowders were used in lithium-ion cells for lithium storage. [Copyright &y& Elsevier]

A series of Sn-coated graphite composite materials for lithium-ion batteries were prepared by microencapsulating nanosize Sn particles in graphite. The nanosize Sn particles are homogeneously dispersed in the graphite matrix via electroless chemical reduction. The tin-graphite composite showed a great improvement in lithium storage capacity. Since Sn is an active element to lithium, Sn can react with lithium to form Li4.4Sn alloys, a reaction accompanied by a dramatic volume increase, whereas the ductile graphite matrix provides a perfect buffer layer to absorb this volume expansion. Therefore, the integrity of the composite electrode is preserved during lithium insertion and extraction. Cyclic voltammetry was employed to identify the reaction process involved in lithium insertion and extraction in the graphite structure, as well as lithium alloying with tin. The tin-graphite composites provide a new type of anode material for lithium-ion batteries with an increased capacity. [ABSTRACT FROM AUTHOR]

Nanoparticle-dispersed polymer electrolytes have been prepared by stirring or high-energy ball milling of polyethylene oxide (PEO), lithium salt (LiCF3SO3, LiClO4 and LiPF6), and nanometer-size ceramic powder (TiO2, SiO2 and Al2O3). The smaller the size of ceramic particles, the better they influence the crystallization kinetics of the PEO polymer chains. High-energy ball milling lowers the glass transition temperature of the composite polymers, and thus increases the ionic conductivity greater than the order of the magnitude compared with the un-milled samples. The highest ionic conductivity was reported when using LiPF6 as added lithium salt and Al2O3 as dispersed particle. Cyclic voltametric measurements showed that the PEO-system is electrochemically stable in the range of 2–5 V. [Copyright &y& Elsevier]

The synthesis and electrochemical characteristics of LiCoxMnyNi1−x−yO2 as cathode materials for rechargeable lithium-ion batteries were investigated. The precursor CoxMnyNi1−x−y(OH)2 was obtained by the chemical co-precipitation method. LiCoxMnyNi1−x−yO2 (0≤x≤0.3, and y=0.2) was prepared by heating a mixture of CoxMnyNi1−x−y(OH)2 and Li2CO3 at 850–900 °C for 24 h in air. The X-ray diffraction (XRD) patterns indicated that pure phase LiCoxMnyNi1−x−yO2 was obtained. The scanning electron micrographs (SEMs) show that the synthesized LiCoxMnyNi1−x−yO2 compounds have good micro-morphology and uniform particle size. The electrochemical properties of these materials such as the galvanostatic charge–discharge performance and cyclic voltammetry were systematically measured. [Copyright &y& Elsevier]

The electrochemical performance of negative electrodes (anodes) made from mesocarbon microbeads (MCMB) in lithium-ion cells has been studied systematically via a variety of electrochemical techniques. The MCMB anodes have a stable lithium intercalation capacity of 325 mAh g−1 on high-rate charge–discharge cycling. Cyclic voltammetry shows only one reduction peak and one oxidation peak, which correspond to lithium-ion intercalation and de-intercalation, respectively. The diffusion of lithium ions in MCMB electrodes is characterized by ac impedance measurements. [Copyright &y& Elsevier]

Cobalt oxides are investigated as anode materials for lithium-ion (Li-ion) batteries by means of a variety of electrochemical characterization techniques. The CoO electrode demonstrates a stable reversible lithium storage capacity of about 300 mAh g−1, even after 30 cycles. The reactivity of the cobalt oxides is attributed to the fact that the products of lithiation are in the form of nanosized products. [Copyright &y& Elsevier]

Abstract: Nanosize cobalt sulfides were synthesized through a one step chemical reaction method at room temperature. The cobalt sulfide nanopowders were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy and electrochemical testing. The results revealed that the cobalt sulfide is a semiconductor; the reversible capacity is increased with increasing content of electronic conductors in the active material of electrodes. The as prepared sample with 10wt.% carbon black and 10wt.% polypyrrole (PPy) powder as electronic conductors shows the best electrochemical properties, with a reversible capacity of over 300mAhg−1 based on the total mass of the electrode. Cobalt sulfide nanopowders show promise as cathode active materials for lithium-rechargeable batteries. [Copyright &y& Elsevier]

Abstract: In this paper, we report on a series of SnO2-carbon nano-composites synthesized by in situ spray pyrolysis of a solution of SnCl2·2H2O and sucrose at 700°C. The process results in super fine nanocrystalline SnO2, which is homogeneously distributed inside the amorphous carbon matrix. The SnO2 was revealed as a structure of broken hollow spheres with porosity on both the inside and outside particle surfaces. This structure promises a highly developed specific surface area. X-ray diffraction (XRD) patterns and transmission electron microscope (TEM) images revealed the SnO2 crystal size is about 5–15nm. These composites show a reversible lithium storage capacity of about 590mAhg−1 in the first cycle. The discharge curve of the composite indicates that lithium is stored in crystalline tin, but not in amorphous carbon. However, the conductive carbon matrix with high surface area provides a buffer layer to cushion the large volume change in the tin regions, which contributes to the reduced capacity fade compared to nonacrystalline SnO2 without carbon. [Copyright &y& Elsevier]

Abstract: A novel conducting sulphur-polypyrrole composite material was prepared by the chemical polymerization method with sodium p-toluenesulphonate as the dopant, 4-styrenesulphonic sodium salts as the surfactant, and FeCl3 as the oxidant. The new material was characterized by Raman spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Nanosize polypyrrole particles were uniformly coated onto the surface of the sulphur powder, which significantly improved the electrical conductivity, the capacity and the cycle durability in a lithium cell compared with the bare sulphur electrode. [Copyright &y& Elsevier]