Phosphorus, nitrogen and oxygen co-doped polymer-based core-shell carbon sphere for high-performance hybrid supercapacitors

Co-doping heteroatoms of the carbon lattice has been proven as an efficient strategy that can improve the capacitive performance, due to the synergetic effect of several dopants. Herein, a series of phosphorus, nitrogen and oxygen, co-doped polymer-based carbon spheres were prepared by the suspension polymerization method and chemical activation with phosphoric acid at different temperatures. The presence of heteroatoms was confirmed by X-ray photoelectron spectroscopy and elemental analysis. The structure of the carbons was characterized by scanning electron microscopy, Raman spectroscopy and nitrogen adsorption. Carbon obtained at 800 degrees C with a P, N and O doping level of 11.17 at%, 2.79 at% and 11.77 at% respectively, shows a capacitance of 157 F g(-1) at the current density of 0.05 A g(-1). Moreover, the electrode can survive at a wide potential window of 1.5 V with only 15% decrease in capacity after 10000 cycles at a current density of 5 A g(-1), providing a high energy density of 10 Wh kg(-1) and a high power density of 750 W kg(-1). For the outstanding features, it is expected that the phosphorus, nitrogen and oxygen co-doped carbons will be a very suitable material not only for supercapacitors, but also for lithium batteries and oxygen reduction reaction. In addition, the co-doping method described here might be extended to the preparation of other kinds of porous carbon materials. (c) 2018 Elsevier Ltd. All rights reserved

Facile electrochemical synthesis of few layered graphene from discharged battery electrode and its application for energy storage

AbstractA cost-effective, simple and non-hazardous route for synthesis of few-layered graphene from waste zinc carbon battery (ZCB) electrodes via electrochemical expansion (ECE) has been reported. In this synthesis, we have electrochemically exfoliated the graphene layers, by intercalating sodium dodecyl benzenesulfonate (SDBS) surfactant into graphitic layers at different D.C. voltages with a constant SDBS concentration. The graphene sheets were isolated, purified and characterized by Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD), Raman spectrometry, Ultraviolet absorption (UV), Selected area electron diffraction (SAED) and Cyclic voltammetry. Best result was obtained at 4.5V of D.C. A possible mechanism for the intercalation process has been proposed. A promising application of the produced material for supercapacitor application has also been explored in combination with polyaniline

2D film of carbon nanofibers elastically astricted MnO microparticles: A flexible binder-free anode for highly reversible lithium ion storage

MnO as anode materials has received particular interest owing to its high specific capacity, abundant resources and low cost. However, it is still a serious problem that large volume change (>170%) during the lithiation/delithiation processes results in poor rate capability and fast capacity decay. With homogenous crystals of MnO grown in the network of carbon nanofibers(CNF)，binding effect of CNFs can effectively weaken the volume change of MnO during cycles. In this work, CNF/MnO flexible electrode for lithium-ion batteries is designed and synthesized. The carbon nanofibers play the roles of conductive channel and elastically astricting MnO particles during lithiation/delithiation. CNF/MnO as binder-free anode delivers specific capacity of 983.8 mAh g−1 after 100th cycle at a current density of 0.2 A g−1, and 600 mAh g−1 at 1 A g−1 which are much better than those of pure MnO and pure CNF. The ex-situ FESEM images of CNF/MnO clearly show the relative volume change of MnO/CNF as anode under various discharging and charging time. CNFs can elastically buffer the volume change of MnO during charging/discharging cycles. This work presents a facile and scalable approach for synthesizing a novel flexible binder-free anode of CNF/MnO for potential application in highly reversible lithium storage devices

Supercapacitors (electrochemical capacitors)

International audienceRapid development of the technologies based on electric energy in the last decades have stimulated intensive research on efficient power sources. Electrochemical energy conversion and storage systems are based on Faradaic reactions (charge transfer) and electrostatic attraction of ions at the electrode/electrolyte interface. The latter might be an interesting solution for applications requiring moderate energy density, high power rates, and long cycle life. Electrochemical capacitors (ECs) store the charge in a physical manner, hence, their energy density is moderate. At the same time, the lack of electrochemical reactions ensures very high power and long cycle life compared to batteries. Activated carbons with their versatile properties (like specific surface area, well-developed and suitable porosity, heteroatoms in the graphene matrix) are the most popular materials in EC application. This chapter provides a comprehensive overview of the carbon-based materials recently developed, with special attention devoted to those obtained by biomass carbonization and activation. Electrochemical properties demonstrated by such carbons are discussed in respect to their physicochemical characteristic

Iron and Copper Containing Oxygen Reduction Catalysts From Templated Glucose-Histidine

International audienceNitrogen doped carbons loaded with non-precious transition metals are currently investigated as substitutes of Pt-based catalysts for oxygen reduction in Polymer Electrolyte Fuel Cells (PEMFC's). This paper reports the preparation of one kind of such catalysts using glucose/histidine mixtures added with Fe and Cu salts in the presence of silica gels as hard templating agent to increase carbon surface area. The resulting carbons contain nitrogen in amounts that depend on heating temperature (T=600 and T=900°C) on the glucose/histidine molar ratio and, more weakly, on the relative Fe/Cu amount. Surface areas are a function of reactant concentration and heating temperature, whereas pore size and pore size distribution only depend on glucose-histidine molar ratio. Cyclic voltammetry results on oxygen reduction depend on Fe/Cu ratio, the best result both in terms of incipient oxygen reduction potentials and currents being observed on samples only containing Fe, with no Cu added