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Abstract: The electronic structures of Mg-doped LiCoO2 have been investigated by the first-principle pseudopotential method. The effect of Mg-doping content on the band structure and structural stability of LiCoO2 is presented. The results obtained via a full relaxation of the crystalline structure show that a rational amount of Mg-doping in LiCoO2 is helpful to enhance its electronic conductivity. However, the doping magnitude should be controlled within 15mol% of LiCoO2 in order to keep its crystalline structure unchanged. By combining total energy calculations with basic thermodynamics, the average intercalation voltages of this doped system have been predicted. [Copyright &y& Elsevier]

Abstract: The La–Ni system compounds have been prepared by arc-melting method under Ar atmosphere. X-ray diffraction analysis reveals that the as-prepared alloys consist of different phases. The electrochemical properties, including activation, maximum discharge capacity, high rate chargeability (HRC), and high rate dischargeability (HRD) of these alloy electrodes have been studied through the charge–discharge recycle testing at different temperatures and charge (or discharge) currents. Among the La–Ni alloy electrodes studied, LaNi2.28 alloy has the most excellent high rate charging performance, and La2Ni7 alloy exhibit the highest high rate dischargeability, while La7Ni3 alloy is capable of discharging at low temperature. [Copyright &y& Elsevier]

Abstract: Adsorption behavior of metal atom M (M = Cu, Ag, Au) on CeO2(100), a technologically important catalytic support surface, is studied by using first-principles density-functional theory calculations with the on-site Coulomb interaction taken into account (DFT + U). Prior to geometry optimization, small distortions in selected Ce–O distances are imposed to explore the energetics associated with reduction of Ce4+ to Ce3+ due to charge transfer to Ce during M adsorption. Results indicate that the adsorption is accompanied by an electron charge transfer between neutral metal atom and neighboring Ce4+ cation. For the same adsorption site, there exist multiple adsorption configurations with the excess electron localized at various nearest neighboring Ce ion relative to the M. The order on adsorption energies of M on CeO2(100) surface follows: Cu > Au > Ag. The atomic and electronic structures of M on CeO2(100) are compared with those of M on CeO2(111) and CeO2(110). [Copyright &y& Elsevier]

Abstract: A novel composite material Li2NaV2(PO4)3/C is developed by utilizing our latest finding to form less stable rhombohedral Li3V2(PO4)3 directly with partial substitution of Li+ to Na+ ions. In the prepared sample, rhombohedral Li3V2(PO4)3 becomes the dominant phase with a proportion of ∼59%, coexistent with monoclinic Li3V2(PO4)3 (10%) and rhombohedral Na3V2(PO4)3 (31%). High-resolution transmission electron microscopy (HRTEM) reveals that different phases coexist in the same primary particles. This characteristic is different from other cathodes, in which the primary particles are single- or poly-crystals. The prepared composite delivers a discharge capacity of 119.1 mAh g−1, of which 93.6% is centralized around 3.7 V vs. Li/Li+, in good agreement with phase''s ratio calculated from refinement. The plateaus of monoclinic Li3V2(PO4)3, appeared at 3.6 and 4.1 V vs. Li/Li+, play an additional role of indicator to warn the end of charge and discharge. This kind of electrode materials are particular suitable to build large batteries to power electric vehicles and shape the grid. [Copyright &y& Elsevier]

Abstract: Surface structures and electronic states of metal (M =Cu, Ag and Au) adsorbed on CeO2(111) surface have been investigated using first-principles density-functional theory calculations with the on-site Coulomb interaction taken into account. Results indicate that the adsorption is accompanied by an electron charge transfer between neutral metal atom and neighboring Ce4+ cation. Charge redistribution with electron localized on the various Ce cations neighboring to adsorbed atom is observed and can be attributed to local structural distortion effects. For the same adsorption site, the structural configuration with the electron localized on the surface Ce cation away from the adsorbed metal atom M is energetically favorable. The strongest adsorption interaction for Cu and Ag is located at 3-fold subsurface O-top site, whereas 2-fold surface O-bridge site is the most stable for Au adsorption. The order on the adsorption energy follows the sequence of Cu>Ag>Au, indicating that Cu atom has a stronger interaction with CeO2(111) surface than Ag and Au. Previous controversies about the localization of the transferred electron and the valence state of the adsorbed Au atom have been successfully clarified via analysis of the local structural distortions. [Copyright &y& Elsevier]