Large-Scale Synthesis of Nitrogen-Doped Activated Carbon Fibers with High Specific Surface Area for High- Performance Supercapacitors

Activated carbon nanofibers (ACFs) with high specific surface area, excellent conductivity, and narrow pore-size distribution, are regarded as a promising electrode material for high-performance supercapacitors (SCs). Herein, a facile route to synthesize large-scale amorphous CF (a-CF) using catalytic pyrolysis of acetylene (C2H2) at 260 C over copper catalysts is reported. The conversion rate of acetylene into a-CF is estimated as high as 72.05 wt%. Subsequently, the as-prepared a-CF is transformed into ACFs by potassium hydroxide (KOH) at 800 C with high specific surface area and porous structures. Moreover, nitrogen-doped ACFs are conducted in the activation step through a physical mixing of a-CF/KOH/melamine with various ratios. For SCs, the as-prepared N-ACFs display excellent specific capacitance and cycle stability. In the three-electrode system, the N-ACF (CF-03) demonstrates a specific capacitance value of 227 F g1 at 0.5 A g1, and shows a 94% capacitance retention after a long cycle (10 000 cycles) at 2 A g1. Moreover, the CF-03-based two-electrode SC demonstrates a high energy density of 14.30 Wh kg1 and a high power density of 79.88Wkg1 in 1 M Na2SO4 electrolyte. Herein, a simple and promising way to prepare large-scale a-CF, ACF, and N-doped ACFs is demonstrated.