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Abstract: LiFePO4/carbon and LiFe1−x Co x PO4/carbon (x =0.02, 0.04, 0.08 and 0.1) composite cathode materials were synthesized by citrate gel technique. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to study the phase and morphology of un-doped and Co doped lithium iron phosphate/carbon composites. The SEM images revealed that the particles were agglomerated and the particle sizes were almost homogeneously distributed. The particle size was found to be between 200 and 300nm from transmission electron microscopy. Cyclic voltammetric studies were taken to investigate the electrochemical performance of the prepared composite materials. The high intensity of the anodic and cathodic peaks indicates that Li-ions and electrons were participating actively in redox reactions due to the carbon coating. Charge/discharge studies carried out on a CR2032 coin cell revealed that the carbon coated LiFePO4/carbon composite exhibited an improved discharge capacity of 157mAh/g at low rates. We found that cobalt doping does not have a favourable effect on the electrochemical performance of lithium iron phosphate cathode materials. [Copyright &y& Elsevier]

Abstract: LiFePO4, doped LiM x Fe1−x PO4, and Li1−x M x FePO4 compounds have been prepared via a sol–gel synthesis method. The physical properties of the as-prepared lithium iron phosphates were characterised by X-ray diffraction, X-ray absorption near-edge spectroscopy (XANES), and magnetic susceptibility. The electrochemical properties lithium iron phosphates were tested by a variety of electrochemical techniques. Lithium iron phosphate electrodes demonstrated a stable discharge capacity of 160–165mAhg−1, almost approaching the theoretical capacity. The good electronic conductivity and nanocrystalline could contribute to the unique performance of lithium iron phosphate electrodes. Lithium iron phosphates have a significant potential to be used as a new cathode materials in Li-ion batteries. [Copyright &y& Elsevier]

Abstract: Si thin films were deposited directly on stainless steel substrates that act as current collectors using the pulsed laser deposition (PLD) technique. Amorphous Si films of different thicknesses were obtained at the Ar gas pressure of 5×10−5 Torr and a temperature of 500°C but different deposition times. The microstructure and morphology of the films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and atomic force microscopy (AFM). The anodic electrochemical performance of the films was examined in the range of 0.005–1.5V, which revealed excellent cyclic stability without any large capacity fade up to the 70th cycle. The PLD process was suitable for improving the density and adhesion behavior of the films. [Copyright &y& Elsevier]

Abstract: A series of polypyrrole-LiFePO4 (PPy-LiFePO4) composites were synthesised by polymerising pyrrole monomers on the surface of LiFePO4 particles. AC impedance measurements show that the coating of polypyrrole significantly decreases the charge-transfer resistance of LiFePO4 electrodes. The electrochemical reactivity of polypyrrole and PPy-LiFePO4 composites for lithium insertion and extraction was examined by charge/discharge testing. The PPy-LiFePO4 composite electrodes demonstrated an increased reversible capacity and better cyclability, compared to the bare LiFePO4 electrode. [Copyright &y& Elsevier]

Abstract: Stoichiometric and non-stoichiometric Mg-doped lithium iron phosphates were synthesised via spray-pyrolysis, followed by sintering at high temperature for crystallization. The spray pyrolysis process allows the homogeneous mixing of the ingredient reactants at atomic level. The electronic conductivities of the Mg-doped lithium iron phosphates have been drastically improved by 4 orders of magnitude, comparing to the undoped LiFePO4. The electrochemical properties of as-prepared lithium iron phosphates were systematically measured by cyclic voltammetry and constant current charge/discharge cycling tests. [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]

LiCoO2 cathode materials have been prepared by a spray-drying technique. The stoichiometry of the materials, their morphology, and the phase composition and electrochemical performance have been studied. The effects of thermal annealing and decomposition processes on the structure are discussed in detail. The changes of Li content in materials were monitored by ICP spectrometry. It was established that the decomposition of the acetates at around 450 °C is a slurry-making process that compacts the powder. It was found that well lithiated samples with good life cycle and high capacity can be prepared using acetate precursors and a spray solution technique. The morphology, grain size and texturing can be controlled by the sintering time and temperature in combination with intermediate grinding. [Copyright &y& Elsevier]

Several multiple-ion-doped lithium nickel oxides with formula of LiMnxCoyNi1−x−yO2 were synthesized via solid-state reactions at high temperature. These phase-pure LiMnxCoyNi1−x−yO2 compounds have a layered hexagonal structure, and their electrochemical properties were systematically investigated. Typical cathodes can deliver a capacity in the range of 140–180 mAh/g with fairly stable cyclability. The kinetics of lithium insertion in these cathodes were characterized via ac impedance measurements. These newly developed compounds show great promises as cathode materials for future lithium-ion batteries with low cost and less toxicity. [Copyright &y& Elsevier]

Abstract: LiFePO4 is a promising environmentally friendly and low cost alternative cathode material for use in lithium-ion batteries. The most common materials production process used to manufacture LiFePO4 is solid-state synthesis which entails several grinding and recalcination steps, occurring over many hours. We report on the synthesis of crystalline LiFePO4 in only 10min via a versatile process of Electric discharge assisted mechanical milling (EDAMM). Preliminary electrochemical testing of the synthesized powder demonstrates good capacity and excellent cyclability. The EDAMM technique offers an exciting opportunity to synthesize a range of new and existing materials to be used in a variety of energy storage applications that include rechargeable lithium batteries, hydrogen fuel cells, and supercapacitors. [Copyright &y& Elsevier]

We present order-of-magnitude conductivity data for “carbon-included” lithium iron phosphate (LFP) powders lightly pelletised as used as cathodes in Li-ion batteries. The powders were synthesised by a spray pyrolysis method, with a short ameliorating sinter to optimise phase purity. Carbon was introduced into the materials by adding stoichiometric amounts of sucrose into the starting ingredients. We obtained X-ray diffraction patterns and electrical conductivity estimates for carbon contents of between 0 and 31 wt.%. The resultant conductivities spanned almost seven orders of magnitude. [Copyright &y& Elsevier]