Nitrogen-self-doped mesoporous carbons synthesized by the direct carbonization of ferric ammonium citrate for high-performance supercapacitors

Journal of Solid State Electrochemistry - We report a simple method of synthesizing nitrogen-self-doped mesoporous carbons by the direct carbonization of ferric ammonium citrate (FAC) in an inert...     

Facile preparation of hierarchical porous carbons for supercapacitors by direct carbonization of potassium humate

Journal of Solid State Electrochemistry - A simple, cost-effective, and environmentally friendly strategy for the preparation of porous carbons for supercapacitors via direct carbonization of...     

Porous carbon as electrode material in direct ethanol fuel cells (DEFCs) synthesized by the direct carbonization of MOF-5

Porous carbon (PC-900) was prepared by direct carbonization of porous metal-organic framework (MOF)-5 (Zn₄O(bdc)₃, bdc?=?1,4-benzenedicarboxylate) at 900 °C. The carbon material was deposited with PtM (M?=?Fe, Ni, Co, and Cu (20 %) metal loading) nanoparticles using the polyol reduction method, and catalysts PtM/PC-900 were designed for direct ethanol fuel cells (DEFCs). However, herein, we are reporting PtFe/PC-900 catalyst combination which has exhibited superior performance among other options. This catalyst was characterized by powder XRD, high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and selected area electron diffraction (SAED) technique. The electrocatalytic capability of the catalyst for ethanol electrooxidation was investigated using cyclic voltammetry and direct ethanol single cell testing. The results were compared with those of PtFe and Pt supported on Vulcan XC72 carbon catalysts (PFe/CX-72 and Pt/XC-72) prepared via the same method. It has been observed that the catalyst PtFe/PC-900 developed in this work showed an outstanding normalized activity per gram of Pt (6.8 mA/g Pt) and superior power density (121 mW/cm² at 90 °C) compared to commercially available carbon-supported catalysts.     

Lignin-derived hierarchical porous carbon for high-performance supercapacitors

Journal of Solid State Electrochemistry - Lignin as the second most abundant natural polymer was applied to prepare a hierarchical porous carbon (HPC) for supercapacitors (SCs). Direct activation...     

A high-performance carbon derived from polyaniline for supercapacitors

Activated carbon derived from rod-shaped polyaniline (the diameter of 170 nm) was synthesized by carbonization and subsequent activation with KOH. The obtained activated carbon exhibits a high specific capacitance (455 F g^?1) and remarkable rate capability due to its high specific surface area (1976 m² g^?1), narrow pore size distribution (< 3 nm) as well as short diffusion length. It is indicated that the promising synthetic method used in this work can pave the way for designing new carbon based materials from different polymers for high-performance energy applications.     

Hierarchical porous carbon derived from Allium cepa for supercapacitors through direct carbonization method with the assist of calcium acetate

Hierarchical porous carbon was prepared from onion through a direct carbonization method and it was used as suercapacitor electrode material.     

Hierarchical porous carbon derived from coal-based carbon foam for high-performance supercapacitors

Hierarchical porous carbon (HPC) from bituminous coal was designed and synthesized through pyrolysis foaming and KOH activation. The obtained HPC (NCF-KOH) were characterized by a high specific surface area (S_BET) of 3472.41 m²/g, appropriate mesopores with V_mes/V_total of 57%, and a proper amount of surface oxygen content (10.03%). This NCF-KOH exhibited a high specific capacitance of 487 F/g at 1.0 A/g and a rate capability of 400 F/g at 50 A/g based on the three-electrode configuration. As an electrode for a symmetric capacitor, a specific capacitance of 299 F/g at 0.5 A/g was exhibited, and the specific capacitance retained 96% of the initial capacity at 5 A/g after 10,000 cycles. Furthermore, under the power density of 249.6 W/kg in 6 mol/L KOH, a high energy density of 10.34 Wh/kg was obtained. The excellent charge storage capability benefited from its interconnected hierarchical pore structure with high accessible surface area and the suitable amount of oxygen-containing functional groups. Thus, an effective strategy to synthesize HPC for high-performance supercapacitors serves as a promising way of converting coal into advanced carbon materials.     

Recent advances in carbon nanostructures prepared from carbon dioxide for high-performance supercapacitors

The burgeoning global economy during the past decades gives rise to the continuous increase in fossil fuels consumption and rapid growth of CO₂ emission,which demands an urgent exploration into green and sustainable devices for energy storage and power management.Supercapacitors based on activated carbon electrodes are promising systems for highly efficient energy harvesting and power supply,but their promotion is hindered by the moderate energy density compared with batteries.Therefore,scalable conversion of CO₂ into novel carbon nanostructures offers a powerful alternative to tackle both issues:mitigating the greenhouse effect caused by redundant atmospheric CO₂ and providing carbon materials with enhanced electrochemical performances.In this tutorial review,the techniques,opportunities and barriers in the design and fabrication of advanced carbon materials using CO₂ as feedstock as well as their impact on the energy-storage performances of supercapacitors are critically examined.In particular,the chemical aspects of various Cv2 conversion reactions are highlighted to establish a detailed understanding for the science and technology involved in the microstructural evolution,surface engineering and porosity control of CO₂-converted carbon nanostructures.Finally,the prospects and challenges associated with the industrialization of CO₂ conversion and their practical application in supercapacitors are also discussed.     

Thiourea aldehyde resin-based carbon/graphene composites for high-performance supercapacitors

Thiourea aldehyde resin-based heteroatom doping carbon and graphene composites (RHDC/GN) were prepared by an in situ polymerization and carbonization. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that thiourea aldehyde resin deposited on lamellar GO flakes during the polymerization and RHDC/GN composites had a hierarchical structure. The specific capacitance of the RHDC/GN composites was high up to 355 F g^?1, much higher than that of the pure thiourea aldehyde resin-based heteroatom doping carbon (RHDC) with specific capacitance of 135 F g^?1 at a current density of 1.0 A g^?1 in 6-M KOH electrolyte. And the hetroatoms in RHDC/GN composites increase the specific capacitance, and GN enhances the conductivity of the electrodes which is beneficial to improving electrochemical cycling stability of the electrode significantly. The specific capacitance retains 90.97% after 5000 charge-discharge processes at 10 A g^?1, which provides potential as supercapacitors.     

N,P dual-doped hollow carbon spheres for high-performance supercapacitors

Journal of Solid State Electrochemistry - A series of nitrogen (N) and phosphorus (P) dual-doped hollow carbon spheres (NPHCSs) with different contents of N and P were synthesized by Stöber...     

Pomegranate rind-derived activated carbon as electrode material for high-performance supercapacitors

In this paper, activated carbon materials were synthesized from pomegranate rind through carbonization and alkaline activation processes. The effects of pyrolytic temperature on the textual properties and electrochemical performance were investigated. The surface area of the activated carbon can reach at least 2200 m² g^?1 at different pyrolytic temperatures. It was found that, at the range of 600–900 °C, decreasing the carbonization temperature leads to the increase of t-plot micropore area, t-plot micropore volume, and capacitance. Further decreasing the carbonization temperature to 500 °C also leads to the increase of t-plot micropore area and t-plot micropore volume, but the capacitance is slightly poorer. The activated carbon carbonized at 600 °C and activated at 800 °C possesses very high specific area (2931 m² g^?1) and exhibits very high capacitance (～268 F g^?1 at 0.1 A g^?1 and ～242 F g^?1 at 1 A g^?1). There is no capacitance fading after 2000th cycle.     

Network-like holey NiCo2O4 nanosheet arrays on Ni foam synthesized by electrodeposition for high-performance supercapacitors

Journal of Solid State Electrochemistry - To achieve high-performance supercapacitors, electrode materials with the accessible electrode area, electrons, and ions diffusion channels are strongly...     

Porous surfur-doped hard carbon for excellent potassium storage

Hard carbon is promising anode for potassium-ion batteries(PIBs),however,the poor rate capability hinders its development as potential anode.To address this question,we design a sulfur-doped porous hard carbon(S-HC)for PIBs through the combination of structural design and composition adjustment.The as-designed S-HC exhibits a long cycling life with^191 mAh/g after 300 cycles at 1 A/g,and an excellent rate capability with^100 mAh/g at 5 A/g,which was attributed to its structural characteristics and compositions.The S-HC demonstrates to be promising anode in the future.     

Biomass-derived porous carbon electrode modified with nanostructured nickel-cobalt hydroxide for high-performance supercapacitors

Journal of Solid State Electrochemistry - Apple-derived porous carbon (denoted as APC) is successfully prepared and analyzed as a potential carbon material by hydrothermal carbonization and...     

Sulfur-decorated nanomesh graphene for high-performance supercapacitors

Sulfur-decorated nanomesh graphene(S@G) has been synthesized by a 155℃ heat treatment of a mixture of nanomesh graphene and S. The as-obtained S@G materials keep a high specific surface area,and exhibit obviously enhanced conductivity and hydrophilicity as compared to the pristine graphene.X-ray photoelectron spectroscopy and thermogravimetric analysis indicate that most S atoms in the S@G samples are stably combined with nanomesh graphene via covalent bonds rather than exist as free elemental S. As an electrode material for aqueous supercapacitors, the S@G with a S content of 5 wt% delivers a specific capacitance up to 257 F/g at the current density of 0.25 A/g, which is 23.6% higher than that of the undoped graphene. Our results provide a simple approach to scalable synthesis of S-doped porous carbon materials, which have potential applications in the high-performance capacitive energy storage devices.     

Structure of carbon nanoparticles synthesized by adiabatic compression of acetylene and their application in supercapacitors

The work reports the study of the structure of carbon nanoparticles prepared by the pyrolysis of heliumdiluted acetylene under adiabatic compression in a piston reactor. At a pushing gas pressure of 0.5 MPa, 0.7 MPa, and 0.9 MPa the reaction gas was heated to temperatures of 400 °C, 600 °C, and 750 °C. By transmission electron microscopy it is found that carbon nanoparticles have a spherical shape and their size varies from 20 nm to 60 nm. The structural features of carbon nanoparticles are determined from the X-ray photoelectron spectroscopy data and the analysis of the near-edge X-ray absorption fine structure spectroscopy. Carbon nanoparticles prepared at a pushing gas pressure of 0.5 MPa have an amorphous structure and consist of hydrogenated carbon with impurities of polycyclic aromatic fragments. At a stronger compression ratio, carbon nanoparticles with a layered structure consisting mainly of sp² hybridized carbon atoms are formed. The capacitance behavior and electrochemical impedance of carbon nanoparticle-based supercapacitors are compared.     

Mesopore-dominant porous carbon derived from bio-tars as an electrode material for high-performance supercapacitors

For the first time, toxic bio-tars collected from the gasification of pine sawdust are used as the precursor for activated carbons. Various types of activation agents including KOH, K₂CO₃, H₃PO₄ and ZnCl₂ were screened for obtaining superior activated carbons. When KOH was used as an activation agent, the obtained activated carbons exhibited high specific surface area and large mesopore volume. The activated carbons were further employed to be the electrode material of supercapacitors, and its specific capacitance reached up to 260 F g^?1 at 0.25 A g^?1 current density. Also, it showed an excellent rate performance from preserving a relatively high specific capacitance of 151 F g^?1 at 50 A g^?1. The assembled device also exhibited the good electrochemical stability with the capacity retention of 90% after 5000 cycles. Furthermore, the maximum energy density of the activated carbons in organic electrolyte reached 17.8 Wh kg^?1.     

Electrodeposited NiSe_2 on carbon fiber cloth as a flexible electrode for high-performance supercapacitors

A flexible electrode of nickel diselenide/carbon fiber cloth(NiSe_2/CFC) is fabricated at room temperature by a simple and efficient electrodeposition method. Owing to NiSe_2 character of nanostructure and high conductivity, the as-synthesized electrodes possess perfect pseudocapacitive property with high specific capacitance and excellent rate capability. In three-electrode system, the electrode specific capacitance of the NiSe_2/CFC electrode varies from 1058 F g~(-1) to 996.3 F g~(-1) at 2 A g~(-1) to 10 A g~(-1) respectively, which shows great rate capability. Moreover, the NiSe_2 electrode is assembled with an active carbon(AC) electrode to form an asymmetric supercapacitor with an extended potential window of 1.6 V. The asymmetric supercapacitor possesses an excellent energy density 32.7 Wh kg~(-1) with a power density 800 W kg~(-1) at the current density of 1 A g~(-1). The nanosheet array on carbon fiber cloth with high flexibility, specific capacitance and rate capacitance render the NiSe_2 to be regarded as the promising material for the high performance superconductor.     

3D crumbled MXene for high-performance supercapacitors

MXene materials have recently attracted considerable attention in energy storage application owing to their metallic conductivity, 2D structure and tunable surface terminations. However, the restacking of 2D MXene nanosheets hinders the ion transport and accessibility to the surface, resulting in adverse effect on their electrochemical performances. Here, with the assistance of hexamethylenetetramine (C₆H₁₂N₄), 2D Ti₃C₂T_x MXene nanosheets were fabricated into a 3D architecture with crumbled and porous structure through an electrostatic self-assembly followed by annealing. The resultant 3D structure can expose massive active sites and facilitates the ion transport, which is beneficial for sufficient utilization of the outstanding superiorities of the MXene. Therefore, as a pseudocapacitive material, the 3D crumpled and porous Ti₃C₂T_x MXene shows a gravimetric capacitance of 333 F/g at 1 A/g, and maintains 261 F/g and 132 F/g at ultrahigh current densities of 100 A/g and 1000 A/g, respectively, revealing promising potential for application in supercapacitors.