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

Abstract

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 g−1 at 0.5 A g−1, and shows a 94% capacitance retention after a long cycle (10 000 cycles) at 2 A g−1. Moreover, the CF‐03‐based two‐electrode SC demonstrates a high energy density of 14.30 Wh kg−1 and a high power density of 79.88 W kg−1 in 1 m Na2SO4 electrolyte. Herein, a simple and promising way to prepare large‐scale a‐CF, ACF, and N‐doped ACFs is demonstrated.

Melt Spinning of Low-Cost Activated Carbon Fiber with a Tunable Pore Structure for High-Performance Flexible Supercapacitors

“…Activated carbon fiber (ACF) is a fibrous activated carbon made of organic fiber as raw material through high-temperature carbonization and activation, which is a commercial product that can be purchased directly from the market . With large SSA, high conductivity, small thermal expansion coefficient, and corrosion resistance, ACFs hold great promise as flexible electrode materials for SCs. , However, the pore structure of ACF is mainly composed of interlaminar pores between graphite sheets and pores caused by the destruction of the carbon material structure, which is mainly micropore with narrow pore size distribution, thus reducing the utilization of its ultrahigh SSA …”

Perspective on Micro-Supercapacitors

“…The accumulated charge during discharge returns to the electrolyte and generates a discharge current in the external circuit. At present, the electrode materials of a mainly include activated carbon ( Wei et al, 2012 ; Wei and Yushin, 2012 ; Lei et al, 2013 ; Mori et al, 2019 ), carbon nanotubes ( Zhou et al, 2014 ; Wang et al, 2016 ; Chang et al, 2018 ; Kshetri et al, 2018 ), carbon nanofiber ( Liao et al, 2020 ), graphene ( Kim et al, 2020 ; Wong et al, 2020 ), carbon materials ( Xing et al, 2015 ; Xing et al, 2018 ) and aerogel ( Fang and Binder, 2006 ; Zhang et al, 2006 ; Liu et al, 2018a ), which have the characteristics of high conductivity, high strength, corrosion resistance, and high temperature resistance Figure 2B . The cyclic voltammogram (CV) curve ( Figure 2C ) and the galvanostatic charge/discharge (GCD) curve ( Figure 2D ) of the response of the EDLC exhibit rectangular and triangular shapes, respectively.…”

Honeycomb-like Hierarchical Porous Activated Carbons from Biomass Waste with Ultrahigh Specific Surface Area for High-Rate Electrochemical Capacitors

“…For EDLCs, porous carbons, for example, activated carbon (AC) are extensively utilized as electrode materials by reason of their high SSA, adequate electrical conductivity, and high stability in electrochemistry. − Thus, numerous research groups have developed several carbon-based materials, for example, porous carbons (AC), carbon nanofibers, carbon nanotubes, graphene, and have demonstrated high performance in EDLCs. − Nevertheless, a facile route to effectively produce porous carbons for fast charge–discharge performance in EDLC with a low cost of mass fabrication still remains the main challenge. Recently, porous carbons converted from discarded biomass have displayed a promising way to create highly effective carbon electrode materials used in EDLCs with massive production and cost efficiency. − ,− …”

“…Biomass wastes are environmentally friendly and renewable resources with abundant availability to serve as cost-effective carbon precursors. ,− ,− Naturally abundant biomass is mostly composed of cellulose, hemicellulose, lignin, and carbon components with various characteristics that can be converted into porous carbons by carbonization and activation. − ,− Previous reports demonstrated that biomass-derived porous carbon used in EDLC electrodes can deliver high capacitances of 300–350 F g –1 at current densities of 0.5–5 A g –1 with aqueous electrolytes. − These achievements reveal biomass-waste-based carbon electrodes to be abundantly available for EDLC. However, for aqueous electrolytes, fast charge–discharge behaviors among EDLCs, usually measured at a current density of 50–200 A g –1 , should be studied more.…”