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Li J.,South China Normal University | Li J.,Power Generation of Guangdong Higher Education Institutes | Ru Q.,South China Normal University | Ru Q.,Power Generation of Guangdong Higher Education Institutes | And 8 more authors.
Electrochimica Acta | Year: 2013

A novel multi-step design of spherical nano-SnSb/MCMB/carbon core-shell composite for high stability and long life lithium battery electrodes has been introduced. The core-shell composite was successfully synthesized via co-precipitation and subsequent pyrolysis. The resultant composite sphere consisted of nanosized SnSb alloy and mesophase carbon microbeads (MCMB, 10 μm) embedded in a carbon matrix pyrolyzed from glucose and petroleum pitch, in which the MCMB was treated to be the inner core to offer mechanical support and efficient electron conducting pathway. The composite material exhibited a unique stability with a retention discharge capacity rate of 83.52% with reversible capacity of 422.5 mAh g-1 after 100 cycles and a high initial coulombic efficiency of 83.53%. The enhanced electrochemical performance is attributed to the structural stability of the composite sphere during the charging-discharging process. © 2013 Elsevier Ltd. All rights reserved.

Yi J.,South China Normal University | Lu D.,South China Normal University | Li X.,South China Normal University | Li X.,Power Generation of Guangdong Higher Education Institutes | And 5 more authors.
Journal of Solid State Electrochemistry | Year: 2012

A porous titania has been prepared by using polystyrene spheres and tri-block copolymer ((EO) 20-(PO) 70-(EO) 20, P123) as templates, and its structure, composition, and performance as anode of lithium ion battery are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction, and galvanostatic charge/discharge test. The results from SEM and TEM indicate that the prepared porous titania has a trimodal pore system, in which the pores are in ordered arrangement and interconnected with the same pore diameter and uniform wall thickness. The charge/discharge tests show that the battery using the prepared porous titania as anode exhibits good rate capacity and cycle stability. © 2011 Springer-Verlag.

Mei-Xiang X.,South China Normal University | Xuan X.,South China Normal University | Xuan X.,Power Generation of Guangdong Higher Education Institutes | Xiao-Xuan H.,South China Normal University
Jiegou Huaxue | Year: 2010

To study the Cu-Cu interaction and stability of the title complexes, the structures of complexes [Cu(Ph2Ppy)(CH2CN)]+1, [Cu(Ph2Ppy)]+2, [Cu2(Ph2Ppy) 2(CH3CN)2]2+ 3, [Cu 2(Ph2Ppy)2(CH3CN)]2+4, [Cu2(Ph2Ppy)2]2+5 and [Cu 2(Ph2Ppy)3(CH3CN)]2+6 were calculated by density functional theory PBE0 method, and the following conclusions can be drawn: (1) There is no orbital overlapping between two Cu atoms, indicating no Cu-Cu orbital interaction exists in complexes 3̃6. Due to a breakdown of the closed shell configuration of Cu atoms, the weak Cu-Cu interactions result from the 3dCu → 4sCu' charge-transfer in 4̃6. The Cu-Cu interaction strength follows 5 > 6 > 4, implying that there are stronger Cu-Cu interactions in the complexes with fewer CH3CN or more Ph2Ppy ligands. (2) The calculated interaction energies suggest that the coordination of Cu to Ph 2Ppy is stronger than that to CH3CN. In 3̃6, there are weaker interactions between Cu and CH3CN or Ph2Ppy in the complexes with more CH3CN or Ph2Ppy ligands. (3) The P-Cu and N-Cu interactions are much stronger than the Cu-Cu interaction, so we mainly attribute the stabilities of the binuclear complexes to the eight-membered rings Cu2P2N2C2.

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