Vanadium （III） phosphate monoclinic VPO4·H2O was synthesized hydrothermally. The ε-VOPO4 nanosheets, formed by the oxidative de-intercalation of protons from monoclinic VPO4·H2O, can reversibly react wit...Vanadium （III） phosphate monoclinic VPO4·H2O was synthesized hydrothermally. The ε-VOPO4 nanosheets, formed by the oxidative de-intercalation of protons from monoclinic VPO4·H2O, can reversibly react with more than 1 mol lithium atoms in two steps. Crystal XRD analysis revealed that the structure of the ε-VOPO4 nanosheets is monoclinic with lattice parameters of α=7.2588（4） A, b=6.8633（2） A and c=7.2667（4） A. The results show that the ε-VOPO4 nanosheets have a thickness of 200 nm and uniform crystallinity. Electrochemical characterization of the ε-VOPO4 monoclinic nanosheets reveals that they have good electrochemical properties at high current density, and deliver high initial capacity of 230.3 mA· h/g at a current density of 0.09 mA/cm2. Following the first charge cycle, reversible electrochemical lithium extraction/insertion at current density of 0.6 mA/cm2 affords a capacity retention rate of 73.6% （2.0？4.3 V window） that is stable for at least 1000 cycles.展开更多
Hierarchical SnO2 nanoflowers assembled by atomic thickness nanosheets were prepared by facile one-pot solvothermal method with acetone/water mixture as solvent. The crystal structure, morphology and the microstructur...Hierarchical SnO2 nanoflowers assembled by atomic thickness nanosheets were prepared by facile one-pot solvothermal method with acetone/water mixture as solvent. The crystal structure, morphology and the microstructure of the as-prepared products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and atomic force microscope （AFM）. Results revealed that the nanoflowers （2-4 μm） were assembled by the ultrathin SnO2 nanosheets （3.1 nm esti- mated by AFM）. When tested as anode material for lithium ion batteries, the SnO2 nanoflowers showed improved cy- cling stability comparing with the commercial SnO2 parti- cles. The reversible charge capacity of SnO2 nanoflowers maintained 350.7 mAh/g after 30 cycles, while that of the commercial SnO2 was only 112.2 mAh/g. The high re- versible capacity and good cycling stability could be ascri- bed to the hierarchical nanostructure, atomic thickness nanosheets and large surface area of the SnO2 nanoflowers.展开更多
基金Projects(51172065,51404097,51504083,U1404613)supported by the National Natural Science Foundation of ChinaProject(16A150009)supported by the Key Scientific Research Project for Higher Education of Henan Province,China+2 种基金Project(16A150009)supported by the Natural Science Foundation of Henan Province(General Program)ChinaProject(166115)supported by the Postdoctoral Science Foundation of Henan Province,China
文摘Vanadium （III） phosphate monoclinic VPO4·H2O was synthesized hydrothermally. The ε-VOPO4 nanosheets, formed by the oxidative de-intercalation of protons from monoclinic VPO4·H2O, can reversibly react with more than 1 mol lithium atoms in two steps. Crystal XRD analysis revealed that the structure of the ε-VOPO4 nanosheets is monoclinic with lattice parameters of α=7.2588（4） A, b=6.8633（2） A and c=7.2667（4） A. The results show that the ε-VOPO4 nanosheets have a thickness of 200 nm and uniform crystallinity. Electrochemical characterization of the ε-VOPO4 monoclinic nanosheets reveals that they have good electrochemical properties at high current density, and deliver high initial capacity of 230.3 mA· h/g at a current density of 0.09 mA/cm2. Following the first charge cycle, reversible electrochemical lithium extraction/insertion at current density of 0.6 mA/cm2 affords a capacity retention rate of 73.6% （2.0？4.3 V window） that is stable for at least 1000 cycles.
基金supported by the National Natural Science Foundation of China(21475085,21271125 and B010601)the Innovation Scientists and Technicians Troop Construction Projects of Henan Province,Program for Innovative Research Team in Science and Technology in University of Henan Province(2012TRTSTHN018)
文摘Hierarchical SnO2 nanoflowers assembled by atomic thickness nanosheets were prepared by facile one-pot solvothermal method with acetone/water mixture as solvent. The crystal structure, morphology and the microstructure of the as-prepared products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and atomic force microscope （AFM）. Results revealed that the nanoflowers （2-4 μm） were assembled by the ultrathin SnO2 nanosheets （3.1 nm esti- mated by AFM）. When tested as anode material for lithium ion batteries, the SnO2 nanoflowers showed improved cy- cling stability comparing with the commercial SnO2 parti- cles. The reversible charge capacity of SnO2 nanoflowers maintained 350.7 mAh/g after 30 cycles, while that of the commercial SnO2 was only 112.2 mAh/g. The high re- versible capacity and good cycling stability could be ascri- bed to the hierarchical nanostructure, atomic thickness nanosheets and large surface area of the SnO2 nanoflowers.
