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International audienceAnatase TiO2 nanoparticles were prepared by a simple sol-gel method at moderate temperature. X-ray powder diffraction (XRD) and Raman spectroscopy revealed the exclusive presence of anatase TiO2 without impurities such as rutile or brookite TiO2. Thermogravimetric analysis confirmed the formation of TiO2 at about 400 °C. Particle size of about 20 nm observed by transmission electron microscopy matches well with the dimension of crystallites calculated from XRD. The electrochemical tests of the sol-gel-prepared anatase TiO2 show promising results as electrode for lithium-ion batteries with a stable specific capacity of 174 mAh g−1 after 30 cycles at C/10 rate. The results show that improvement of the electrochemical properties of TiO2 to reach the performance required for use as an electrode for lithium-ion batteries requires not only nanosized porous particles but also a morphology that prevents the self-aggregation of the particles during cycling

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Ethylene diamine tetra-acetic acid (EDTA) was used to prepare spinel LiMn 2 O 4 at 650 °C. The prepared sample by EDTA (E-LiMn 2 O 4 ) is compared with another spinel sample (C-LiMn 2 O 4 ) prepared by citric acid as a common chelating agent at the higher temperature (800 C) adjusted to obtain the same size and shape of the particles as in (E-LiMn 2 O 4 ) sample, as probed by SEM and TEM images. Investigation of both samples by X-ray diffraction showed that both samples have the single phase cubic spinel LiMn 2 O 4 phase with space group Fd-3m. Vibration properties obtained from Raman scattering (RS) and Fourier Transform Infra-Red (FTIR) spectroscopy for both samples are identical with spinel LiMn 2 O 4 structure. 7 Li MAS NMR and XPS spectra show that the amount of Mn 4+ is larger in LiMn 2 O 4 sample prepared by citric acid. LiMn 2 O 4 sample prepared using EDTA as chelating agent has better structural properties, but the improvement of the electrochemical properties is much smaller than the results reported in the literature for lamellar compounds and silicate materials. This is attributed to the features specific to the spinel, which limit both the capacity and cycle ability: dissolution of manganese and Jahn-Teller distortions associated to Mn 3+ ions, that are not modified by the choice of chelating agent.

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A series of Li(Ni1/3Mn1/3Co1/3)1−xMxO2 (M = Al, Mg, Zn, and Fe, x = 0.06) was prepared via sol-gel method assisted by ethylene diamine tetra acetic acid as a chelating agent. A typical hexagonal α-NaFeO2 structure (R-3m space group) was observed for parent and doped samples as revealed by X-ray diffraction patterns. For all samples, hexagonally shaped nanoparticles were observed by scanning electron microscopy and transmission electron microscopy. The local structure was characterized by infrared, Raman, and Mössbauer spectroscopy and 7Li nuclear magnetic resonance (Li-NMR). Cyclic voltammetry and galvanostatic charge-discharge tests showed that Mg and Al doping improved the electrochemical performance of LiNi1/3Mn1/3Co1/3O2 in terms of specific capacities and cyclability. In addition, while Al doping increases the initial capacity, Mg doping is the best choice as it improves cyclability for reasons discussed in this work.