Porous ultrathin carbon nanobubbles formed carbon nanofiber webs for high-performance flexible supercapacitors

Development of novel and scalable high-performance carbon nanomaterials and nanostructures is of critical importance for practical applications of flexible supercapacitors. In this study, we report a unique type of all-carbon nanofibrous non-woven web, in which carbon nanofibers are formed from wellconnected porous ultrathin carbon nanobubbles. The foamed porous structures are achieved using ethanol as a carbon source coating on an electrospun ZnO nanofiber template followed by removing the ZnO template via a reduction and evaporation process. As a candidate for flexible supercapacitor applications, the fabricated integrated carbon nanofiber webs exhibit a long cycling life with 94.1% capacitance retention even after 35 000 cycles at a current density of 10 A g(-1) with a three-electrode configuration. The symmetric supercapacitors also show a high rate performance with 81.4% capacitance retention when the current density is increased 70 times from 0.5 to 35 A g(-1). Furthermore, electrochemical testing of the flexible symmetric devices displays almost the same capacitive behavior in different bending states. These excellent electrochemical performances are attributed to the interconnected porous and bubbled structures of the carbon nanofiber webs.