Tin-embedded carbon nanofibers as flexible and freestanding electrode materials for high-performance supercapacitors

Tin carbon nanofibers were prepared by electrospinning and carbonization as flexible and independent supercapacitor materials. Sn/CNFs, Sn/SnO/CNFs, and SnO2/CNFs were prepared by different carbonization processes. The specific capacitances at 0.5 A g−1 were 761.39 F g−1, 712.29 F g−1, and 589.78 F g−1, respectively. The composite nanofibers were characterized by SEM, XPS, TEM, XRD, and Raman spectroscopy. It was found that tin nanoparticles were well dispersed in carbon nanofibers and no aggregated crystalline phase was formed. These results showed that Sn/CNFs was superior to Sn/SnO/CNFs and SnO2/CNFs in electrochemical performance of supercapacitors. In addition, a very stable cycle stability had been achieved. Even after 10,000 charge-discharge cycles, Sn/CNFs still maintain excellent specific capacitance of up to 114% of its initial performance. Moreover, Sn/CNFs//CNFs was assembled as a flexible all-solid-state asymmetric supercapacitor (ASC) with the energy density of 57.18 Wh kg−1 at a power density of 374.97 W kg−1.