We demonstrate a facile route for the massive production of SnCb/carbon nanocomposite used as high-capacity anode materials of nextgeneration lithium-ion batteries.The nanocomposite had a unique structure of ultrafine...We demonstrate a facile route for the massive production of SnCb/carbon nanocomposite used as high-capacity anode materials of nextgeneration lithium-ion batteries.The nanocomposite had a unique structure of ultrafine SnO2 nanocrystals(5 nm,80 wt%) homogeneously dispersed in amorphous carbon matrix.This structure design can well accommodate the volume change of Li+ insertion/desertion in SnO2,and prevent the aggregation of the nanosized active materials during cycling,leading to superior cycle performance with stable reversible capacity of 400 mAh/g at a high current rate of 3.3 A/g.展开更多
Monodispersed spheroidal SnO2 nanocrystals with the grain size of 8-30 nm were synthesized by the precipitation method using SnCl4·5H2O (stannic chloride hydrate) as raw materials.Differential scanning calorime...Monodispersed spheroidal SnO2 nanocrystals with the grain size of 8-30 nm were synthesized by the precipitation method using SnCl4·5H2O (stannic chloride hydrate) as raw materials.Differential scanning calorimetry/thermogravimetry (DSC/TG),X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to characterize the structure of SnO2 nanocrystals.The influences of the calcination temperature and time on the lattice constant,the lattice distortion and the grain size of SnO2 nanocrystals were discussed based on the XRD results.The grain growth kinetics of SnO2 nanocrystals during calcination process was simulated with a conventional grain growth model which only took into account of diffusion and with a new isothermal model proposed by our group,which took into account of both diffusion and surface reactions.Using conventional model,the grain growth rate constant of SnO2 crystals is 1.55×104nm5/min with a pre-exponential factor of 5 and an activation energy of 108.62 kJ/mol.Compared with the convention model,the new isothermal model is more realistic in reflecting the grain growth behavior of SnO2 nanocrystals during the calcination process.This indicates that the grain growth of SnO2 nanocrystals is controlled by both diffusion and reaction factors,and the effect of surface reactivity on the grain growth of SnO2 nanocrystals could not be ignored.A combined activation energy estimated with the new isothermal model is 53.46 kJ/mol.展开更多
Er3+ ions embedded in silica thin films co-doped by SnO2 nanocrystals are fabricated by sol-gel and spin coating methods. Uniformly distributed 4-am SnO2 nanocrystals are fabricated, and the nanocrystals showed tetra...Er3+ ions embedded in silica thin films co-doped by SnO2 nanocrystals are fabricated by sol-gel and spin coating methods. Uniformly distributed 4-am SnO2 nanocrystals are fabricated, and the nanocrystals showed tetragonal rutile crystalline structures confirmed by transmission electron microscope and X-ray diffraction measurements. A strong characteristic emission located at 1.54 〉m from the Era+ ions is iden- tified, and the influences of Sn doping concentrations on photoluminescence properties are systematically evaluated. The emission at 1.54 #m from Era+ ions is enhanced by more than three orders of magnitude, which can be attributed to the effective energy transfer from the defect states of SnO2 nanocrystals to nearby Er3+ ions, as revealed by the selective excitation experiments.展开更多
基金supported by the National Science Foundation of China(Grant No.51201065 and No.51231003)the Natural Science Foundation of Guangdong Province(S2012040008050)the Doctorate Foundation of Ministry of Education(Grant No.20120172120007 and No.2014ZZ0002)
文摘We demonstrate a facile route for the massive production of SnCb/carbon nanocomposite used as high-capacity anode materials of nextgeneration lithium-ion batteries.The nanocomposite had a unique structure of ultrafine SnO2 nanocrystals(5 nm,80 wt%) homogeneously dispersed in amorphous carbon matrix.This structure design can well accommodate the volume change of Li+ insertion/desertion in SnO2,and prevent the aggregation of the nanosized active materials during cycling,leading to superior cycle performance with stable reversible capacity of 400 mAh/g at a high current rate of 3.3 A/g.
基金Funded by the International Cooperation of Science and Technology Ministry PRC (2005DFBA028)the Nation Undergraduate Innovation Experimentation Plan of Education Ministry PRC (LA08025)
文摘Monodispersed spheroidal SnO2 nanocrystals with the grain size of 8-30 nm were synthesized by the precipitation method using SnCl4·5H2O (stannic chloride hydrate) as raw materials.Differential scanning calorimetry/thermogravimetry (DSC/TG),X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to characterize the structure of SnO2 nanocrystals.The influences of the calcination temperature and time on the lattice constant,the lattice distortion and the grain size of SnO2 nanocrystals were discussed based on the XRD results.The grain growth kinetics of SnO2 nanocrystals during calcination process was simulated with a conventional grain growth model which only took into account of diffusion and with a new isothermal model proposed by our group,which took into account of both diffusion and surface reactions.Using conventional model,the grain growth rate constant of SnO2 crystals is 1.55×104nm5/min with a pre-exponential factor of 5 and an activation energy of 108.62 kJ/mol.Compared with the convention model,the new isothermal model is more realistic in reflecting the grain growth behavior of SnO2 nanocrystals during the calcination process.This indicates that the grain growth of SnO2 nanocrystals is controlled by both diffusion and reaction factors,and the effect of surface reactivity on the grain growth of SnO2 nanocrystals could not be ignored.A combined activation energy estimated with the new isothermal model is 53.46 kJ/mol.
基金supported by the Natural Science Foundation of Jiangsu Province (No. BK2010010)the "333"Projectthe Fundamental Research Funds for the Central Universities (Nos. 1112021001 and 1116021003)
文摘Er3+ ions embedded in silica thin films co-doped by SnO2 nanocrystals are fabricated by sol-gel and spin coating methods. Uniformly distributed 4-am SnO2 nanocrystals are fabricated, and the nanocrystals showed tetragonal rutile crystalline structures confirmed by transmission electron microscope and X-ray diffraction measurements. A strong characteristic emission located at 1.54 〉m from the Era+ ions is iden- tified, and the influences of Sn doping concentrations on photoluminescence properties are systematically evaluated. The emission at 1.54 #m from Era+ ions is enhanced by more than three orders of magnitude, which can be attributed to the effective energy transfer from the defect states of SnO2 nanocrystals to nearby Er3+ ions, as revealed by the selective excitation experiments.