Nitrogen- and oxygen-enriched 3D hierarchical porous carbon fibers: synthesis and superior supercapacity

Abstract

A nitrogen- and oxygen-enriched hierarchical porous carbon fiber was fabricated by phase-separable wet-spinning and the subsequent chemical activation of polyacrylonitrile (PAN) precursors. The wet-spinning could readily offer an interpenetrating 3D meso-/macro-porous network owing to the phase-separation of PAN in the coagulation bath (DMSO/H₂O), caused by the different solubility of PAN in DMSO and H₂O, and the different content of PAN in the fiber and the coagulation bath. The latter chemical activation introduced abundant small-sized nanopores within the meso-/macro-porous network skeleton. The obtained hierarchical porous carbon fiber exhibited a high specific surface area of 2176.6 m² g⁻¹ and a large pore volume of 1.272 cm³ g⁻¹, and was highly doped with heteroatoms of nitrogen and oxygen. When it was used as a supercapacitor electrode, high performance of reversible specific capacitances of 329 F g⁻¹ at 0.1 A g⁻¹ and 223 F g⁻¹ at 20 A g⁻¹ as well as the capacitance retention of 97.6% after 2000 cycles were achieved in a two-electrode cell.