Hierarchically mesoporous carbon nanopetal based electrodes for flexible supercapacitors with super-long cyclic stability

Abstract

Hierarchically mesoporous carbon nanopetals (CNPs) are synthesized on unidirectional carbon fibers (UCFs) by catalytic chemical vapour deposition. The CNPs synthesized on UCFs (CNPs/UCFs) are further used as electrode-cum-current collectors for fabricating a flexible supercapacitor. Highly bendable and electrically conductive UCFs are used as both the substrate for the growth of CNPs and current collectors for the supercapacitor and no other separate current collectors are used in this study. The CNPs/UCF hybrids are characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and Brunauer–Emmett–Teller surface area measurements. The electrochemical performance of the CNPs/UCF supercapacitor is examined by electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge measurements. The mesoporous CNPs/UCF hybrid electrode based symmetric supercapacitor is highly bendable and the performance of the supercapacitor is unaltered even at severe bending angles. The CNPs/UCF supercapacitor exhibits a high gravimetric capacitance of 154 F g⁻¹ with a high specific power density of 32 kW kg⁻¹ at a current density of 16.66 mA cm⁻². The enhanced supercapacitive performance of the CNPs/UCF supercapacitor is mainly due to the mesoporous electrode nanostructure as well as due to the presence of oxygen-containing functional groups on the surface of CNPs/UCF hybrids. The CNPs/UCF supercapacitor possesses a super-long cyclic stability of more than 28 900 cycles. The supercapacitive performance of the CNPs/UCF supercapacitor is comparable to that of those utilizing other carbon nanomaterial based electrodes.