Nitrogen- and Sulfur-Doped Carbon Obtained from Direct Hydrothermal Carbonization of Cellulose and Ammonium Sulfate for Supercapacitor Applications

Abstract

Achieving heteroatom-doped carbon materials using inorganic matter as the doping source is one of the major challenges for renewable energy storage materials. In this letter, a direct simple and reproducible methodology was designed for the preparation of nitrogen- and sulfur-doped materials by direct hydrothermal carbonization (300 °C for 1 h) of cellulose and ammonium sulfate at a mass ratio of 1:1. This N- and S-doped carbon exhibited an excellent electrochemical performance including high specific capacitance (227.3 F/g) when the current density is 1 A/g; however, its specific capacitance still retained 76.55% from the original when the current density was increased to 20 A/g,.

Tunable Synthesis of 3D Niobium Oxynitride Nanosheets for Lithium-Ion Hybrid Capacitors with High Energy/Power Density

“…To quantitatively reflect the contribution of the capacitive behavior, eq can be rewritten as , where i (V) and v are the total current response and scan rate, respectively. k 1 and k 2 represent adjustable parameters.…”

“…In addition, the service lifetime of LIBs may be obviously shortened while charging and discharging under high-current conditions. In comparison, electric double-layer SCs possess higher power densities and better durability due to the fast adsorption/desorption processes, but suffer from poor energy densities. − Fortunately, lithium-ion hybrid capacitors (LIHCs), which integrate the advantages of the aforementioned two kinds of electrochemical energy storage devices, could achieve high energy/power density and durable service life simultaneously. − Active materials commonly used for LIBs with typical faradaic electrochemical reactions to store energy will be adopted as one electrode for LIHCs, while the other electrode uses materials with capacitive characteristics, relying on the electric double-layer capacitance effect. − However, the electrochemical performance of LIHCs is still unsatisfactory because the kinetics of the Faraday reaction is slower than that of the electric double-layer process. The key to improve the performance of LIHCs is to design novel electrode materials that can balance the kinetic difference between the two electrodes. − …”

Nitrogen and Oxygen Codoped Carbon Anode Fabricated Facilely from Polyaniline Coated Cellulose Nanocrystals for High-Performance Li-Ion Batteries

“…29,42 On the other hand, the simultaneous and homogeneous doping of N and O could improve the wettability of carbonaceous electrode materials to Li + . 20,22,23,26,27,29 Benefiting from the relatively large specific surface area and synergistic effects of N and O codoping, the as-prepared c-CNC/PANi electrode with improved reversible capacity, good rate capability, and excellent long-term cycling performance becomes a promising anode material for the fabrication of Li-ion batteries with high energy and power density.…”

“…Significantly, the electronic conductivity could be efficiently enhanced by the introduction of negatively charged N and O heteroatoms. Moreover, the codoped heteroatoms could induce lots of defects in the carbon matrix, which provided a large number of anchoring sites for storing Li + . , On the other hand, the simultaneous and homogeneous doping of N and O could improve the wettability of carbonaceous electrode materials to Li + . ,,,,, Benefiting from the relatively large specific surface area and synergistic effects of N and O codoping, the as-prepared c-CNC/PANi electrode with improved reversible capacity, good rate capability, and excellent long-term cycling performance becomes a promising anode material for the fabrication of Li-ion batteries with high energy and power density.…”

“…In order to promote the electrochemical performance of the carbon based electrode material, the doping of heteroatoms such as N, S, oxygen (O), etc. in carbonaceous materials is proved to be an efficient way. ,− It is known that more extrinsic defects and additional reaction sites could be generated with the doping of heteroatoms; meanwhile, the wettability of the carbonaceous matrix to Li ions would be improved. ,− Xu et al prepared a N self-doped porous carbon anode material by carbonizing the chitosan/CNC biocomposite at 1200 °C. The obtained materials displayed an average specific capacity of 333 mAh g –1 at 100 mA g –1 .…”