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Abstract: Layered intercalation compounds LiM0.02Co0.98O2 (M=Mo6+, V5+, Zr4+) have been prepared using a simple solid-state method. Morphological and structural characterization of the synthesized powders is reported along with their electrochemical performance when used as the active material in a lithium half-cell. Synchrotron X-ray diffraction patterns suggest a single phase HT-LiCoO2 that is isostructural to α-NaFeO2 cannot be formed by aliovalent doping with Mo, V, and Zr. Scanning electron images show that particles are well-crystallized with a size distribution in the range of 1–5μm. Charge–discharge cycling of the cells indicated first cycle irreversible capacity loss in order of increasing magnitude was Zr (15mAhg−1), Mo (22mAhg−1), and V (45mAhg−1). Prolonged cycling the Mo-doped cell produced the best performance of all dopants with a stable reversible capacity of 120mAhg−1 after 30 cycles, but was inferior to that of pure LiCoO2. [Copyright &y& Elsevier]

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]

LiTi2(PO4)3 with a Na+ superionic conductor (NASICON)-type structure is prepared by a two-step solid-state reaction. X-ray diffraction (XRD) confirms that the LiTi2(PO4)3 compound has a NASICON structure, i.e. rhombohedral (space group: R3c). It is found that lithium can be electrochemically inserted into the LiTi2(PO4)3 structure, with a maximum intake of 5.2 mol of lithium per mole of LiTi2(PO4)3 compound, and that [PO4] tetrahedra can participate in the redox reaction. This corresponds to a lithium-storage capacity of 360 mAh g−1. The kinetic parameters of lithium insertion in LiTi2(PO4)3 NASICON are determined by means of ac impedance technique. The charge-transfer resistance (RCT) and exchange current density (i0) are invariable regardless of the state of lithium insertion. This is associated with the unique structure characteristics of the NASICON skeleton. By contrast, the diffusion coefficient, DLi of lithium varies with the state of lithium insertion. The value of DLi is in the range 1.4×10−11 to 1.2×10−9 m2 s−1, which is much higher than for other intercalation materials. [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]

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]

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]

Orthorhombic LiMnO2 was synthesized via the sol–gel process using citric acid as a chelating agent. The effect of varying the molar acid to metal ions ratio (R) on the structural and electrochemical properties of the synthesized compound was studied. Samples with high R (R=1,2) contain large amount of MnO impurity phase, which is electrochemically inactive and thus is detrimental to the electrochemical activity of the electrode. Therefore, the acid to metal ions ratio “R” should not be high. Samples with low R (R=0.5) exhibited a high initial capacity, above 190 mAh/g when cycled at a current density of 0.4 mA/cm2 at room temperature. The ac impedance results show that the initial capacity was improved (compared with ss-o-LiMnO2) due to the smaller particle size and good homogeneity, which improves the Li+ diffusion in the cathode. [Copyright &y& Elsevier]