Search

Designing heteroatom doped metal oxides and modifying them with carbonaceous materials can grant metal oxides with good Li + storage performance because of the improved structure stability and enhanced electric conductivity. Herein, monodispersed Cr-doped SnO 2 quantum dots fixed by graphene nanosheets and carbon layers (C/Cr-SnO 2 /G) were successfully assembled, which showed excellent cyclic stability, high reversible capacity and remarkable rate capability for Li + storage. According to the characteristics results, 3.8 wt% Cr were uniformly incorporated into SnO 2 lattice in form of Cr 3 + , resulting the decrease of SnO 2 diameters. The C/Cr-SnO 2 /G electrodes displayed an excellent reversible capacity of 672 mA h g − 1 after 200 cycles at 100 mA g − 1 without apparent capacity fading throughout the test, and still retained a stable specific capacity of 296 mA h g − 1 even at 5 A g − 1 . The enhanced electrochemical performances of C/Cr-SnO 2 /G can be related to incorporation of Cr into lattice of SnO 2 and the double structure protections by graphene nanosheets and carbon layers, which can easily obtain quantum dots structure, increase the conductivity, and keep the structure stability. [ABSTRACT FROM AUTHOR]

Abstract: A series of monoclinic Li3V2(PO4)3 cathode materials were prepared by H2 reduction (LVP-H2) and carbothermal reduction (LVP-CTR) methods. LVP-H2 showed a primary particle size of about 1 μm, which was much larger than the LVP-CTR samples. A uniform surface carbon layer was observed for the LVP-CTR samples by transmission electron microscope. This carbon layer not only limited the particle growth of the materials but also enhanced the material''s electronic conductivity by five orders of magnitude. The LVP-CTR samples exhibited much better electrochemical performance than LVP-H2. The good electrochemical performance of LVP-CTR was attributed to its nano particle size, high electronic conductivity, as well as the surface carbon layer which limited the vanadium dissolution in electrolyte. [Copyright &y& Elsevier]

Abstract: Binary conductive additives (BCA), formed by sonication of mesoporous carbon (MC) and acetylene black (AB), were used as conductive additives to improve the electrochemical performance of a LiCoO2 composite cathode. The electrochemical performance of the LiCoO2 composite cathode dispersed with BCA was investigated. The results showed that the electrochemical performance (including the discharge capacity, the discharge voltage and the total internal resistance) of a BCA loaded LiCoO2 composite cathode was better than that of a cathode loaded with AB. The possible mechanism is that the MC in BCA can adsorb and retain electrolyte solution, which allows an intimate contact between the lithium ions and the cathode active material LiCoO2 due to its large mesopore specific surface area. A simplified model was also proposed. [Copyright &y& Elsevier]