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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]

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: 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: LiY0.1V3O8 compound was successfully prepared by using a simple, rapid and easily scaled up method, i.e. the rheological phase reaction method. The microstructural characteristics of LiY0.1V3O8 materials were examined by X-ray diffraction and scanning electron microscopy (SEM). Compared with LiV3O8 compound, the LiY0.1V3O8 shows expanded crystal lattices, and the expansion is more significant along the c-axis. The electrochemical properties of the as-synthesized LiY0.1V3O8 compounds were investigated. It was found that the LiY0.1V3O8 electrodes exhibited better reversibility and higher capacities than LiV3O8 electrodes. The reasons for the improved electrochemical performance of the LiY0.1V3O8 electrodes are also discussed. [Copyright &y& Elsevier]

Abstract: A new type of nanostructured titania nanotube supported tin anode was prepared for lithium ion batteries. The as-prepared titania nanotubes are in the anatase phase with diameters of about 12nm. Tin nanoparticles are dramatically decorated on the titania nanotubes and have a particle size of about 10nm. This new structure promises good retention of reversible capacity on cycling for lithium intercalation. By charge/discharge measurements, the reversible capacity of the titania nanotubes supported tin anode for lithiation and de-lithiation was found to be 312mAh/g (cycled between 0.05 and 2.0V) and 203mAh/g (cycled between 0.05 and 1.3V) after 50cycles with around 100% columbic efficiency. [Copyright &y& Elsevier]

Abstract: Spherical porous tin oxide was fabricated via a spray pyrolysis technique. TEM revealed that the primary SnO2 crystals had an average size of about 5nm. The electrochemical measurements showed that the spherical porous SnO2 samples have excellent cyclability, which can deliver a reversible capacity of 410mAhg−1 up to 50 cycles as a negative electrode for lithium batteries. The second step of the study was to thermal treat the initial tin oxide for 3h at 600, 800, 1000 and 1200°C, respectively, in order to identify the particle size effect on the electrochemical performance toward lithium. It was found that the morphologies of these spherical clusters could be maintained even after thermal treatment at 1200°C. It was also proved that finer the size of the tin oxide particles the better the electrochemical performance. [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: 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]

Abstract: Carbon-enriched Li0.98Mg0.02FePO4 compounds were prepared by a novel modified solid-state reaction method Citric acid added to the precursors works as a particle size growth inhibitor as well as a carbon source. Electrochemical evaluation of the Li0.98Mg0.02FePO4 reveals a lithium insertion plateau around 3.4 V vs. Li together with a specific capacity of over 160mAh/g at the C/20 rate. Differential capacity data confirm the two-phase nature of the insertion reactions as well as outstanding ionic reversibility. [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: Co3O4 has shown acceptable electrochemical properties as the anode material of Li secondary batteries. In detail, its capacity reached about 700mAh/g, twice as high as graphite, and 93.4% of initial capacity was retained after 100 cycles. EIS (electrochemical impedance spectroscopy) analyses revealed that after the 1st cycle, the insertion or extraction of Li ions in Co3O4 can occur homogeneously and reversibly (randless-like behavior, homogeneous mixture: Co+Li2O (in the state of Li insertion), Co3O4 (in the state of Li extraction)). In fact, the coulombic efficiency of Co3O4 was almost 100% except for the 1st cycle. According to P. Poizot''s research on several kinds of transition metal oxides, such as Co3O4, CoO, NiO, etc., a small Li2O particle size and catalytic activity of the transition metal are expected to decrease the binding energy of Li2O tremendously. As a result, Li2O should be easy to decompose, and transition metal oxides should be able to charge or discharge reversibly by formation or decomposition of Li2O. However, this assumption has never been confirmed by experimental results. In our results, the CV (cyclic voltammogram) of a Li2O–Co mixture shows much larger oxidation and reduction peaks than that of Li2O. Based on XRD analyses, oxidation and reduction in the CV of Li2O correspond, respectively, to the decomposition and formation of Li2O. So, it can be asserted that Co addition to Li2O facilitates decomposition and formation processes in Li2O and that the catalytic effect of the transition metal must be one of the main causes that make Li2O form or decompose repeatedly. [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]

By varying the synthetic temperature and time, Co3O4 with highly optimized electrochemical properties was obtained from the solid state reaction of CoCO3. As a result, Co3O4 showed a high capacity around 700 mAh/g and stable capacity retention during cycling (93.4% of initial capacity was retained after 100 cycles). However, its initial irreversible capacity reached about 30% of capacity. Several phenomenological examinations in our previous results told us that the main causes of low initial coulombic efficiency, that is, large initial irreversible capacity, were solid electrolyte interphase (SEI) film formation on surface and incomplete decomposition of Li2O during the first discharge process. SEI film formation cannot be restrained without the development of a special electrolyte, and there has been little research on the proper electrolyte composition, whereas in our research, Ni had the catalytic activity to facilitate Li2O decomposition. Thus, in order to improve the low initial coulombic efficiency of Co3O4 (69%), Ni was added to Co3O4 using two methods like physical mixing and mechanical milling. When adding the same amount of Ni, the mechanical milling showed the improvement in initial coulombic efficiency, 79%, but physical mixing had no effect. Finally, when the charge–discharge mechanism of Co3O4 was considered and the morphologies of Ni–Co3O4 mixture obtained by physical mixing and Ni–Co3O4 composite prepared by mechanical milling were compared, it was revealed that the initial coulombic efficiency of Ni–Co3O4 composite depends on the contact area between the Ni and the Co3O4. [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]

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]