Electrospun Sn–SnO2/C composite nanofibers as an anode material for lithium battery applications

Sn–SnO2/C composite nanofibers were prepared by electrospinning method using polyvinyl alcohol as a polymeric agent. X-ray diffraction results of Sn–SnO2/C composite nanofibers confirm the formation of nanocrystalline metallic Tin (Sn) and tetragonal rutile like SnO2. FE-SEM images also showed more void spaces interconnected three-dimensionally in the Sn–SnO2/C composite nanofibers. FE-SEM–EDAX spectra of spherical shape nanoparticles over and inside the nanofibers are confirmed respectively, due to the formation of SnO2 (Sn & O elements) and Sn (Sn element). The charge–discharge results of the newly developed lithium batteries showed a high discharge capacity of 445.2 mAh g−1 and retained the same even after the 30th cycle at a current density of 150 mA g−1. The newly developed lithium batteries also showed the good capacity retention and rate capability. Hence, the electrochemical properties indicate that the newly developed electrospun Sn–SnO2/C composite nanofibers may be a better anode material for lithium-ion batteries

High Capacity Electrospun MgFe2 O4 -C Composite Nanofibers as an Anode Material for Lithium Ion Batteries

MgFe2O4-C composite nanofibers were prepared via electrospinning technique followed by carbonization at 600 °C. Thermogravimetric-differential thermal analysis (TG-DTA) results showed ignition, decomposition and carbonization temperatures of the as-grown fibers. Formation of the nanocrystalline phase of the MgFe2O4 over the amorphous phase of the carbon fibers sample was confirmed from the analysis of the measured XRD results. FE-SEM images of the as-spun and calcined fibers sample showed that the formation of one dimensional (1-D) MgFe2O4-C composite nanofibers and the formed 1-D nanofibers were well interconnected with high porous structured morphology. The electrochemical properties of the MgFe2O4-C composite nanofibers sample were tested as an anode material for lithium-ion battery. Lithium-ion battery made up of the newly developed MgFe2O4-C composite nanofibers sample, used as an anode material, showed discharge capacity of 575 mAh g−1 at a current density of 100 mA g−1 after 20th cycles. Further, the discharge capacity of the lithium-ion battery also measured at a high current density of 1 A g−1 and it was found to be 433 mAh g−1 even after 85 cycles. Also, the lithium-ion battery showed exceptional reversible capacity with the coulombic efficiency of 99.6% even after 85 cycles at a high current density of 1 A g−1. Hence the electrochemical properties suggest that the newly developed MgFe2O4-C composite nanofibers can be used as high capacity anode materials for lithium-ion batteries

LiClO<SUB>4</SUB>- or LiOTf-accelerated 1,3-dipolar cycloaddition reactions: a facile synthesis of cis-fused chromano[4,3-c]isoxazoles

Acetonitrile solutions of lithium perchlorate or lithium triflate are found to accelerate considerably the intramolecular 1,3-dipolar cycloaddition reactions of nitrones derived in situ from hydroxylamines and the O-prenyl derivatives of salicylaldehydes to afford enhanced rates and improved yields of tetrahydrochromano[4,3-c]isoxazole derivatives with high diastereoselectivity. The stereochemistry of the products has been assigned by using extensive NMR studies