SnO_(2)/graphene nanocomposites have been fabricated by a simple chemical method.In the fabrication process,the control of surface charge causes echinoid-like SnO_(2)nanoparticles to be formed and uniformly decorated ...SnO_(2)/graphene nanocomposites have been fabricated by a simple chemical method.In the fabrication process,the control of surface charge causes echinoid-like SnO_(2)nanoparticles to be formed and uniformly decorated on the graphene.The electrostatic attraction between a graphene nanosheet(GNS)and the echinoid-like SnO_(2)particles under controlled pH creates a unique nanostructure in which extremely small SnO_(2)particles are uniformly dispersed on the GNS.The SnO_(2)/graphene nanocomposite has been shown to perform as a high capacity anode with good cycling behavior in lithium rechargeable batteries.The anode retained a reversible capacity of 634 mA·h·g^(–1)with a coulombic efficiency of 98%after 50 cycles.The high reversibility can be attributed to the mechanical buffering by the GNS against the large volume change of SnO_(2)during delithiation/lithiation reactions.Furthermore,the power capability is significantly enhanced due to the nanostructure,which enables facile electron transport through the GNS and fast delithiation/lithiation reactions within the echinoid-like nano-SnO_(2).The route suggested here for the fabrication of SnO_(2)/graphene hybrid materials is a simple economical route for the preparation of other graphene-based hybrid materials which can be employed in many different fields.展开更多
One-dimensional ZnMn2O4 nanowires have been prepared and investigated as anode materials in Li rechargeable batteries. The highly crystalline ZnMn2O4 nanowires about 15 nm in width and 500 nm in length showed a high s...One-dimensional ZnMn2O4 nanowires have been prepared and investigated as anode materials in Li rechargeable batteries. The highly crystalline ZnMn2O4 nanowires about 15 nm in width and 500 nm in length showed a high specific capacity of about 650 mAh.g-1 at a current rate of 100 mA.g-1 after 40 cycles. They also exhibited high power capability at elevated current rates, i.e., 450 and 350 mAh.g 1 at current rates of 500 and 1000 mA.g 1, respectively. Formation of Mn3O4 and ZnO phases was identified by ex situ X-ray diffraction （XRD） and transmission electron microscopy （TEM） studies after the initial discharge-charge cycle, which indicates that the ZnMn2O4 phase was converted to a nanocomposite of Mn3O4 and ZnO phases immediately after the electrochemical conversion reaction.展开更多
基金This work was supported by a grant from the Korea Science and Engineering Foundation(KOSEF)(WCU program,No.31-2008-000-10055-0)a grant from the National Research Foundation of Korea(No.NRF-2009-0094219)funded by the Ministry of Education and Science and Technology(MEST)the Energy Resources Technology R&D program(No.20092020100040)under the Ministry of Knowledge Economy.
文摘SnO_(2)/graphene nanocomposites have been fabricated by a simple chemical method.In the fabrication process,the control of surface charge causes echinoid-like SnO_(2)nanoparticles to be formed and uniformly decorated on the graphene.The electrostatic attraction between a graphene nanosheet(GNS)and the echinoid-like SnO_(2)particles under controlled pH creates a unique nanostructure in which extremely small SnO_(2)particles are uniformly dispersed on the GNS.The SnO_(2)/graphene nanocomposite has been shown to perform as a high capacity anode with good cycling behavior in lithium rechargeable batteries.The anode retained a reversible capacity of 634 mA·h·g^(–1)with a coulombic efficiency of 98%after 50 cycles.The high reversibility can be attributed to the mechanical buffering by the GNS against the large volume change of SnO_(2)during delithiation/lithiation reactions.Furthermore,the power capability is significantly enhanced due to the nanostructure,which enables facile electron transport through the GNS and fast delithiation/lithiation reactions within the echinoid-like nano-SnO_(2).The route suggested here for the fabrication of SnO_(2)/graphene hybrid materials is a simple economical route for the preparation of other graphene-based hybrid materials which can be employed in many different fields.
文摘One-dimensional ZnMn2O4 nanowires have been prepared and investigated as anode materials in Li rechargeable batteries. The highly crystalline ZnMn2O4 nanowires about 15 nm in width and 500 nm in length showed a high specific capacity of about 650 mAh.g-1 at a current rate of 100 mA.g-1 after 40 cycles. They also exhibited high power capability at elevated current rates, i.e., 450 and 350 mAh.g 1 at current rates of 500 and 1000 mA.g 1, respectively. Formation of Mn3O4 and ZnO phases was identified by ex situ X-ray diffraction （XRD） and transmission electron microscopy （TEM） studies after the initial discharge-charge cycle, which indicates that the ZnMn2O4 phase was converted to a nanocomposite of Mn3O4 and ZnO phases immediately after the electrochemical conversion reaction.
