N/P/O/S Heteroatom-Doped Porous Carbon Nanofiber Mats Derived from a Polyacrylonitrile/l-Cysteine/P₂O₅ Precursor for Flexible Electrochemical Supercapacitors

Abstract

It is still a great challenge to achieve high volumetric capacitance without losing gravimetric capacitance and cycling performances for carbon-based electrode materials to fulfill the demands for next-generation supercapacitors. In this work, we have fabricated carbon nanofiber (CNF) mats doped with tetraheteroatoms (N, P, O, and S) via a two-step process: electrospinning and carbonization. The surface porosity, mass density, and doping density of the as-prepared doped CNFs were optimized by varying the l-cysteine-to-potassium pentoxide mass ratio in the polyacrylonitrile (PAN) precursor solution. The structural evaluation of different heteroatom species in the carbon lattice of the as-prepared NPOS-CNFs was systematically studied by various spectroscopic techniques. The optimized NPOS-CNF 12 nanofibers, which were prepared from the PAN precursor containing an l-cysteine/P2O5 mass ratio of 1:2, have a high specific surface area (502.5 m2/g), high mesopore volume (1.561 cm3/g), high mass density (1.07 g/cm3), and highest content (10.34 atom %) of active heteroatom species such as pyrrolic N, pyridinic N, CO, C–S, and C3–PO species. Due to these unique features, the NPOS-CNF 12 exhibited an ultrahigh volumetric capacitance of 625.8 F/cm3 at a current density of 0.2 A/g and also exhibited high gravimetric capacitance (584.8 F/g) and good cycling stability (93.5% capacitance retention after 10 000 cycles) in a 6 M KOH electrolyte. As assembled, the NPOS-CNF 12//NPOS-CNF 12 supercapacitor in a 1 M Na2SO4 electrolyte delivered a high gravimetric energy density of 102.6 Wh/kg at a power density of 105 W/kg with a wide potential window of 0–1.8 V.

Improvement in Electrochemical Performance of Waste Sugarcane Bagasse-Derived Carbon via Hybridization with SiO2 Nanospheres

“…Nearly rectangular-shaped CV curves with a pair of oxidation and reduction peaks centered at −0.49 V and −0.64 V are observed, indicating the involvement of both EDLC and pseudocapacitance mechanisms in the charge storage process. The redox peaks are associated with the reactions given in Equation ( 5) [76]: The redox peaks are associated with the reactions given in Equation ( 5) [76]: There is almost no change in the shape of the CV profiles when the scan rate is increased from 5 to 125 mV/s, indicating the high-rate capability and electrochemical stability of the nanocomposite electrode in Na2SO4 electrolyte. The total current gradually increases with the increasing scan rate.…”

Nitrogen-Doped Activated Hollow Carbon Nanofibers with Controlled Hierarchical Pore Structures for High-Performance, Binder-Free, Flexible Supercapacitor Electrodes

“…The electrochemical performance of EDLC electrodes depends on their surface area and pore size distributions . Therefore, porous carbon materials have been intensively investigated as the electrode material of EDLCs due to their outstanding specific surface area (SSA), controllable porosity, and good electrical conductivity. , Among various carbon materials, carbon nanofibers (CNFs) possess excellent electrical conductivity, chemical stability, and one-dimensional geometry that is useful for ion diffusion. − CNFs can be synthesized using electrospinning and subsequent carbonization, which is a scalable manufacturing method to tune the morphology and chemical functionality of the nanofibers. − …”

Fabrication of Flexible Poly(m-aminophenol)/Vanadium Pentoxide/Graphene Ternary Nanocomposite Film as a Positive Electrode for Solid-State Asymmetric Supercapacitors

“…Electrochemical energy conversion and storage (EECS) technologies, including rechargeable batteries, fuel cells, and supercapacitors, can replace coal-based power supplies. As a next-generation energy storage device, supercapacitors have been proven to be the most reliable and effective alternative to conventional batteries since batteries demonstrate slow power delivery and uptake, a short cycle-life, and a less eco-friendly profile, while supercapacitors offer high power density, a fast delivery rate, high safety performance, and a long-life cycle (up to 10 4 ) [ 1 , 2 ]. For portable and flexible electronics, such as tablets, laptops, and foldable phones, flexible solid-state supercapacitors can serve as a real-time power backup system and micropower source instead of batteries for these flexible smart electronics [ 3 , 4 , 5 , 6 ].…”