An electrospinning technique was used to fabricate TiO2nanofibers for use as binder-free electrodes for lithium-ion batteries. The as-electrospun nanofibers were calcined at 400–1,000°C and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). SEM and TEM images showed that the fibers have an average diameter of ~100 nm and are composed of nanocrystallites and grains, which grow in size as the calcination temperature increases. The electrochemical properties of the nanofibers were evaluated using galvanostatic cycling and electrochemical impedance spectroscopy. The TiO2nanofibers calcined at 400°C showed higher electronic conductivity, higher discharge capacity, and better cycling performance than the nanofibers calcined at 600, 800, and 1,000°C. The TiO2nanofibers calcined at 400°C delivered an initial reversible capacity of 325 mAh·g−1approaching their theoretical value at 0.1 C rate and over 175 mAh·g−1at 0.3 C rate with limited capacity fading and Coulombic efficiency between 96 and 100%.
An aqueous mixture of poly(vinyl alcohol) (M.W. ∼ 8.9 × 10 4 -9.8 × 10 4 g mol −1 , 14% w/v) and disodium terephthalate (Na 2 TP) powders (6% w/v) was electrospun at 14 kV with a fiber collection distance and a feed rate of 12 cm and 0.5 mL h −1 . Then, the obtained fibers were calcined at 350 • C with a heating rate of 1 • C min −1 under air for 7 h. Diameters of hollow Na 2 TP fibers, composed of grains with sizes of 76 ± 27 nm, are 189 ± 32 nm. Na 2 TP fibers are composed of ∼16% w/w Na 2 CO 3 . Na 2 TP structure is orthorhombic and can be indexed in a space group of Pbc2 1 . Degree of crystallinity of Na 2 TP fibers is less than that of Na 2 TP powders. Galvanostatic curves display stable reversible capacities of Na 2 TP powders and fibers at ∼140 mA h g −1 and ∼110 mA h g −1 , respectively, after 50 cycles at 25.5 mA g −1 . On the other hand, at 255 mA g −1 and after 100 cycles, those of the powders and the fibers are ∼48 mA h g −1 and ∼70 mA h g −1 , respectively. Thus, the eco-friendly Na 2 TP fibers are potentially used as anode materials of sodium-ion batteries under high current density.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.