Synthesis of vanadium oxide nanorods coated with carbon nanoshell for a high-performance supercapacitor
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Vanadium oxide (VOx) possesses high-potential pseudocapacitive characteristics. But it is still unsatisfactory for supercapacitors because of the poor ionic diffusivity and electrical conductivity of VOx. Nanocrystallization can decrease the distance of ion diffusion, then improve the ionic diffusivity. Suitable carbon coating could heighten conductivity and provide ion pathways. Here we synthetized V6O13@C by a sol-hydrothermal method, then pyrolyze to form VOx@C core-shell nanorod composites. The carbon nanoshells with abundant pores on the surface of vanadium oxide improve the conductivity of the nanorod electrodes and provide sufficient ion pathways. The microstructure and electrochemical measurements reveal the V6O13@C prepared from 0.8 g V2O5 raw material under 700 °C heating possesses optimal performance. As the electrode materials of a symmetric supercapacitor, such VOx@C core-shell nanorods possess a high capacity (545 F g−1 at 0.5 A g−1, 437 F g−1 at 5 A g−1) and satisfactory cyclability (88.3% retention after 2000 cycles at 0.5 A g−1). SEM and TEM show that the V6O13@C consists of uniform-size nanorods whose diameter is 20 nm with a 7-nm-thickness carbon shell layer. The favorable electrochemical performance is stemmed from unique structural features of V6O13@C nanorods. 1D structure of nanorods could significantly cut down the ion migration process as well as improving ion diffusion kinetics. Carbon nanoshell provides the high conductivity for electron, and the pores provide passageway for ion diffusion.
KeywordsVOx@C core-shell nanorods Sol-hydrothermal method Supercapacitors
This study received financial support from the National Natural Science Foundation of China (21776051), the Natural Science Foundation of Guangdong (2018A030313423), and the Science and Technology Project of Guangzhou (201802020029).
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