Vanadium pentoxide （V205） exhibits high theoretical capacities when used as a cathode in lithium ion batteries （LIBs）, but its application is limited by its structural instability as well as its low lithium and electronic conductivities. A porous composite of V2Os-SnO2/carbon nanotubes （CNTs） was prepared by a hydrothermal method and followed by thermal treatment. The small particles of V205, their porous structure and the coexistence of SnO2 and CNTs can all facilitate the diffusion rates of the electrons and lithium ions. Electrochemical impedance spectra indicated higher ionic and electric conductivities, as compared to commercial V205. The VzOs-SnOz/CNTs composite gave a reversible discharge capacity of 198 mAh.g- 1 at the voltage range of 2.05-4.0 V, measured at a current rate of 200 mA.g-1, while that of the commercial V205 was only 88 mAh.g-1, demonstrating that the porous V2Os-SnOz/CNTs composite is a promising candidate for high-performance lithium secondary batteries.
Qi GuoZhenhua SunMan GaoZhi TanBingsen ZhangDang Sheng Su
A novel and simple ion-exchange method was developed for the synthesis of nano-SnO/micro-C hybrid structure. The structure of the as prepared nano-SnO/micro-C was directly revealed by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. SnO particles with the size about 25 nm were well confined in amorphous carbon microparticles. Carbon matrix in micrometer scale not only acts as a protective buffer for the SnO nanoparticles during the battery cycling processes, but also avoids the shortcomings of nanostructures, such as low tap density and potential safety threats. Electrochemical behaviors of the nano-SnO/micro-C were tested as anode material in lithium ion batteries. The initial reversible capacity is 508 mA h g^-1, and the reversible capacity after 60 cycles is 511 mA h g^-1, indicating good capacity retention ability.
