Flexible Free-Standing VO2(B) Nanobelt Films as Additive-Free Cathode for Lithium-Ion Batteries

Flexible free-standing VO2(B) nanobelt films were designed as additive-free cathode for lithium ion batteries, via self-assembly of VO2(B) nanobelts with a filtration technology. VO2(B) nanobelts with different size were prepared by hydrothermal reaction with various amount of formic acid addition. The phase structure and morphology were analyzed by X-ray diffraction and scanning electron microscopy, which revealed high crystallinity and homogeneous morphology. A constant current charge-discharge test was employed to investigate the electrochemical properties. These films exhibited initial specific capacity of 219.4 mAh/g at current density of 10mA/g in the voltage range 4.0–1.5V vs. Li+/Li. Distinct voltage plateaus around 2.5V were observed, which was seldom reported. The size effect of the materials on electrochemical performance was investigated and the results demonstrated that the electrochemical performance of the VO2(B) nanobelts is significantly impacted by their size