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Liu G.,Chifeng University | Qu J.,Changzhou University | Wang H.,China Aviation Lithium Battery Co.
Journal of Alloys and Compounds | Year: 2013

Ultra thin titanate nanosheets, octahedral TiO2 and spindle-like TiO2 were prepared via a facile hydrothermal route. The morphology and structure of the prepared samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrochemical lithium storage of these samples was studied by galvanostatic method and cyclic voltammetry. It is found that the spindle-like TiO2 with exposed {100} facets show enhanced lithium storage behavior at various current densities as-compared to titanate nanosheets and octahedral TiO2. The origin of good electrochemical performance may result from a lower barrier for surface transmission of Li+ ions through {100} facets. © 2013 Elsevier B.V. All rights reserved.

Shao X.-Z.,Beijing Institute of Technology | Wang L.-S.,Beijing Institute of Technology | Yan G.-Q.,Beijing Institute of Technology | Yan G.-Q.,China Aviation Lithium Battery Co. | Yu G.-M.,Beijing Institute of Technology
Journal of Chemical and Engineering Data | Year: 2013

The solubility of tris(3-hydroxypropyl)phosphine oxide (THPPO) in selected solvents was measured by a static analytic method over the temperature range from (293 to 328) K in methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, acetone, and a binary solvent mixture of ethanol + acetone. Several widely used thermodynamic models, such as the empirical equation and the Buchowski-Ksiazaczak (λh), Scatchard-Hildebrand, Wilson, nonrandom two-liquid (NRTL), and universal quasichemical (UNIQUAC) equations were applied to represent the measurement results. The binary interaction parameters of the above models were found to have a linear dependency on temperature, and the coefficients were regressed. The results show that all of these models can satisfactorily reproduce the experimental data and the NRTL equation can provide the best correlation with an overall relative standard deviation of 0.46 %. © 2013 American Chemical Society.

Li H.,Jiangsu University | Li Y.,Jiangsu University | Chen L.,Jiangsu University | Jiang H.,Jiangsu University | And 3 more authors.
Journal of Alloys and Compounds | Year: 2014

A microwave assisted method is developed for synthesizing pure LiFe 1/3Mn1/3Co1/3PO4 and LiFe 1/3Mn1/3Co1/3PO4/C nanocomposite. Olivine LiFe1/3Mn1/3Co1/3PO4 coated with uniform amorphous carbon film of ∼5 nm in thickness with an average size of ∼200 nm is successfully obtained. Compared with pure LiFe 1/3Mn1/3Co1/3PO4, LiFe 1/3Mn1/3Co1/3PO4/C composite presents enhanced electrochemical Li-ion intercalation performances. It exhibits a high discharge capacity of 169 mA h g-1 at 0.1 C (theoretical capacity is 170 mA h g-1). The capacity retention is 99% after 30 cycles. Furthermore, the capacities are still retained 101 at 5 C and 76 mA h g-1 and 20 C, respectively. Carbon coating can significantly improve the Li-ion diffusion, the reversibility of lithium extraction/insertion and electrical conductivity of LiCo1/3Mn1/3Fe 1/3PO4. © 2014 Elsevier B.V. All rights reserved.

Li H.,Jiangsu University | Chen Y.,Jiangsu University | Chen L.,Jiangsu University | Jiang H.,Jiangsu University | And 5 more authors.
Electrochimica Acta | Year: 2014

Core-shell type olivine solid solutions, LiFe1/3Mn1/3Co1/3PO4/C, are synthesized via a very simple and rapid microwave heating route with different carbon sources. The obatined LiFe1/3Mn1/3Co1/3PO4/C materials are characterized thoroughly by various analytical techniques such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy-dispersive spectroscopy instrument. The particle sizes and distribution of the carbon layer of BP2000 carbon black coated LiFe1/3Mn1/3Co1/3PO4 (LiFe1/3Mn1/3Co1/3PO4/BP) are more uniform than that obtained from acetylene black (LiFe1/3Mn1/3Co1/3PO4/AB) and Super P (LiFe1/3Mn1/3Co1/3PO4/SP). Moreover, the LiFe1/3Mn1/3Co1/3PO4/BP nanocomposite shows superior electrochemical properties such as high discharge capacity of 160 mA h g-1 at 0.1 C, excellent cyclic stability (143 mA h g-1 at 0.1 C after 30 cycles) and rate capability (76 mAh g-1 at 20 C), which are better than other two samples. Cyclic voltammetric and electrical tests disclose that the Li-ion diffusion, the reversibility of lithium extraction/insertion and electrical conductivity are significantly improved in LiFe1/3Mn1/3Co1/3PO4/BP composite. Electrochemical impedance spectroscopy illustrates that LiFe1/3Mn1/3Co1/3PO4/BP composite electrode possesses low contact and charge-transfer impedances, which can lead to rapid electron transport during the electrochemical lithium insertion/extraction reaction. It is believed that olivine solid solution LiFe1/3Mn1/3Co1/3PO4 decorated with carbon from appropriate carbon source is a promising cathode for high-performance lithium-ion batteries. © 2014 Elsevier Ltd. All rights reserved.

Xiang D.-B.,Beijing Institute of Technology | Xiang D.-B.,China Aviation Lithium Battery Co. | Shao H.-B.,Beijing Institute of Technology
Chinese Chemical Letters | Year: 2014

The intramolecular electronic communication and multilevel ion-pairing effect of triferrocenylmethane (TriFcM) in organic phase was studied with the "thin-layer electrochemistry" approach. Three pairs of symmetric peaks in cyclic voltammetry of TriFcM correspond to three one-electron electrochemical reaction processes and indicate strong intramolecular electronic communication, which could be used to study the multilevel ion-pairing effect. Three different formation constants of ion-pairs between the three ferroceniums of TriFcM and perchlorate in thin organic film were obtained and compared. © 2014 Hui-Bo Shao.

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