Flexible wire-like all-carbon supercapacitors based on porous core-shell carbon fibers

Hierarchical porous carbon-based supercapacitors have been attracting intense attention due to their high and stable electrical double-layer capacitance that may be used for advanced technologies. In this study, porous core-shell carbon fibers were produced by a simple and fast acid oxidation treatment of carbon fibers, and the morphological and structural evolution were examined by SEM, TEM and Raman spectroscopic measurements. Detailed electrochemical characterizations showed that the resulting porous core-shell carbon fibers exhibited an excellent performance for charge storage with a specific capacitance of 98 F g(-1) at 0.5 A g(-1) in a 1 M H2SO4 liquid electrolyte and 20.4 F g(-1) at 1 A g(-1) in a H2SO4/PVA solid electrolyte, and excellent capacitance retention at similar to 98.5% for the former and similar to 96% for the latter over 3000 cycles. The results demonstrated that porous core-shell carbon fibers might be used as effective electrode materials for the fabrication of wire-like all-carbon flexible supercapacitors with high physical flexibility and desirable electrochemical properties.