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The structural and electrochemical effects of electrospun V2O5 with selected redox-inactive dopants (namely Na+, Ba2+ and Al3+) have been studied. The electrospun materials have been characterised via a range of analytical methods including X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller surface area measurements and scanning and transmission electron microscopy. The incorporation of dopants in V2O5 was further studied with computational modelling. Structural analysis suggested that the dopants had been incorporated into the V2O5 structure with changes in crystal orientation and particle size, and variations in the V4+ concentration. Electrochemical investigations using potentiodynamic, galvanostatic and impedance spectroscopy analysis showed that electrochemical performance might be dependent on V4+ concentration, which influenced electronic conductivity. Na+- or Ba2+-doped V2O5 offered improved conductivities and lithium ion diffusion properties, whilst Al3+ doping was shown to be detrimental to these properties. The energetics of dopant incorporation, calculated using atomistic simulations, indicated that Na+ and Ba2+ occupy interstitial positions in the interlayer space, whilst Al3+ is incorporated in V sites and replaces a vanadyl-like (VO)3+ group. Overall, the mode of incorporation of the dopants affects the concentration of oxygen vacancies and V4+ ions in the compounds, and in turn their electrochemical performance.ᅟ [ABSTRACT FROM AUTHOR]

α-MoO nanobelts were synthesized by simple hydrothermal method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Cyclic voltammogram (CV) and galvanostatic charge/discharge testing techniques were employed to evaluate electrochemical behaviors of α-MoO materials. Results showed that α-MoO nanobelts with about 80 nm in diameter and 5-12 μm in length were grown in the orthorhombic system. Electrochemical characterisation confirmed that in lithium ion insertion/extraction process, the first intercalation of lithium ion in α-MoO at about 2.8 V was irreversible, corresponding to LiMoO (0 < x ≤ 0.25) and the parent MoO materials coexisting, the second lithium ion inter-calation was reversible at the potential range of 2.2-2.4 V followed by LiMoO (0.25 < x ≤ 0.5), and below 1.0 V the mechanism of lithium ion storage changed from lithium ion intercalation reaction into lithium alloying reaction. The α-MoO nanobelts showed better electrochemical performance, 319 mA h g initial discharge capacity, around 52% capacity retention after 20 cycles than that of α-MoO bulk. [ABSTRACT FROM AUTHOR]

Spinel LiMnO and multidoped spinel LiMnCoCrNiFeO were synthesized by the glycine-nitrate method and coated with lithium borosilicate (LBS) in order to enhance the electrochemical performance at room temperature. The structure and electrochemical performance of all samples were characterized by inductively coupled plasma-mass spectrometer (ICP-MS), X-ray diffraction (XRD), differential thermal analysis/thermogravimetry (DTA/TG), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), atomic force microscopy (AFM) and galvanostatic charge-discharge measurements. The XRD analysis shows that the samples exhibit a pure spinel phase. The SEM results indicated that LBS particles had encapsulated the surface of the undoped and multidoped LiMnO without causing any structural change. The charge-discharge tests showed that LiMnCoCrNiFeO displays better cycling performance than the pristine LiMnO at room temperature. However, in the same conditions, LBS-coated LiMnCoCrNiFeO and LiMn O have better cycling performance than uncoated samples. The results suggest that multidoped and LBS-coated LiMnO could develop into a promising cathode material for lithium ion batteries. [ABSTRACT FROM AUTHOR]

The electronic structure and electrochemical parameters of ternary NiSn0.5Ti0.5 phase are investigated by plane-wave pseudopotential method of the first-principle. The interstitial sites are firstly filled with lithium atoms, and then the substitution for Ni sites occurs. The results show that the Fermi level of lithium-intercalated phase goes up with the increasing lithium concentration. These interactions of M-M covalent bonds (M=Ni, Sn, Ti) become weak, while Li-M bonds are found to increase. NiSn0.5Ti0.5 phase is characterized with high theoretical capacity and low voltage of lithium-intercalation. The obvious volume effect from 77.15% to 189.94% would lead to the failure of the electrode material, and therefore the NiSn0.5Ti0.5 compound should be limited as low as possible in multi-element Sn-based alloy. [ABSTRACT FROM AUTHOR]