Nitrogen‐Doped Porous Carbon Structure from Melamine‐Assisted Polyimide Sheets for Supercapacitor Electrodes

Research on the mechanical thermal stability of micro-porous carbon-based micro composites with marine paint matrices has been carried out. Microporous carbon has the property of absorbing radar waves so it is very interesting to research and develop into a microwave shielding material synthesized from coconut shell (cocoa nucifera) by carbonization process at 600°C for 45 minutes. The molecular structure and phases of micro porous carbon were characterized using Fourier Transform Infrared (FTIR) and X-Ray Diffraction (XRD) with the results confirmed of micro carbon with reduced graphene oxide (rGO) phase. Furthermore, micro-composites made from porous micro carbon with marine paint as a binder were made using the wet mixing-casting method. Mechanical thermal testing was carried out by means of a shear test at a temperature range of 30 – 70°C using a Dynamics Mechanical Analysis (DMA) tool. The test results showed that the value of the storage modulus of porous micro carbon composites was 1.653 MPa, 10.196 MPa, 13.068 MPa, 118.567 MPa, respectively. The value of the composite storage modulus increases with increasing concentration of porous micro carbon with an optimum value of mechanical thermal stability at a composition of 70:30 %wt. The results of mechanical thermal testing showed that porous micro carbon with rGO phase from coconut shells has the potential to be used as an anti-radar shielding material. 068 MPa, 118.567 MPa. The value of the composite storage modulus increases with increasing concentration of porous micro carbon with an optimum value of mechanical thermal stability at a composition of 70:30 %wt. The results of mechanical thermal testing showed that porous micro carbon with rGO phase from coconut shells has the potential to be used as an anti-radar shielding material. 068 MPa, 118.567 MPa. The value of the composite storage modulus increases with increasing concentration of porous micro carbon with an optimum value of mechanical thermal stability at a composition of 70:30 %wt. The results of mechanical thermal testing showed that porous micro carbon with rGO phase from coconut shells has the potential to be used as an anti-radar shielding material.

Potassium-ion batteries with novel N, O enriched corn silk-derived carbon as anode exhibiting excellent rate performance

Carbon materials are promising for use as electrodes for supercapacitors and lithium–ion batteries due to a number of properties, such as non-toxicity, high specific surface area, good electronic conductivity, chemical inertness, and a wide operating temperature range. Carbon-based electrodes, with their characteristic high specific power and good cyclic stability, can be used for a new generation of consumer electronics, biomedical devices and hybrid electric vehicles. However, most carbon materials, due to their low electrical conductivity and insufficient diffusion of electrolyte ions in complex micropores, have energy density limitations in these devices due to insufficient number of pores for electrolyte diffusion. This work focuses on the optimization of a hybrid material based on porous carbon and carbon nanotubes by mechanical mixing. The purpose of this work is to gain new knowledge about the effect of hybrid material composition on its specific capacitance. The material for the study is taken on the basis of porous carbon and carbon nanotubes. Electrodes made of this hybrid material were taken as an object of research. Porous carbon or nitrogen-containing porous carbon (combined with single-, double-, or multi-layer carbon nanotubes (single-layer carbon nanotubes, bilayer carbon nanotubes or multilayer carbon nanotubes) were used to create the hybrid material. The effect of catalytic chemical vapor deposition synthesis parameters, such as flow rate and methane-to-hydrogen ratio, as well as the type of catalytic system on the multilayer carbon nanotubes structure was investigated. Two types of catalysts based on Mo12O28 (μ2-OH)12{Co(H2O)3}4 were prepared for the synthesis of multilayer carbon nanotubes by precipitation and combustion. The resulting carbon materials were tested as electrodes for supercapacitors and lithium ion intercalation. Electrodes based on nitrogen-containing porous carbon/carbon nanotubes 95:5% were found to be the most efficient compared to nitrogen-doped porous carbon by 10%. Carbon nanotubes, bilayer carbon nanotubes and multilayer carbon nanotubes synthesized using the catalyst obtained by deposition were selected as additives for the hybrid material. The hybrid materials were obtained by mechanical mixing and dispersion in an aqueous solution followed by lyophilization to remove water. When optimizing the ratio of the hybrid material components, the most effective porous carbon:carbon nanotubes component ratio was determined.

FeCl3 induced catalytic activation prepared porous carbon with carbon nanotube skeleton from coal for supercapacitor electrodes

Porous carbon nanoplate/Se composite derived from potassium citrate as high-performance Li-Se battery cathode: A study on structure-function relation

Recently, lignocellulosic materials have been widely utilized as feedstocks for several applications such as carbon, biofuels and biochemical productions because of their potentials (i.e. waste reduction, carbon sequestration, renewable). In this study, porous carbon was successfully synthesized from water hyacinth (WHs) via hydrothermal carbonization assisted with chemical activation using Na2CO3 and K2CO3. The hydrothermal carbonization process was studied in the range of 160-200°C for 4-12 h and the hydrothermal chars were then further pyrolyzed under a supply of N2 flow 100 ml/min at 700-900°C for 2 h. The as-pyrolyzed chars were then activated by two different bases including Na2CO3 and K2CO3 at the ratio of 1.0 (w/w, hydrothermal char: chemical) to obtain highly porous carbon. The results indicated that carbon percentage, surface area and porous structure were improved with the higher hydrothermal temperature showing the best results at 180°C for 8 h. Moreover, the development of pore structure of WHs porous carbon was successfully by chemical activation with K2CO3.

Resource use is crucial for the sustainable growth of energy and green low-carbon applications since the improper handling of biomass waste would have a detrimental effect on the environment. This paper used nano-ZnO and ammonium persulfate ((NH4)2S2O8, APS) as a template agent and heteroatom dopant, respectively. Using a one-step carbonization process in an inert atmosphere, the biomass waste furfural residue (FR) was converted into porous carbon (PC), which was applied to the supercapacitor electrode. The impact of varying APS ratios and carbonization temperatures on the physicochemical properties and electrochemical properties of PC was studied. O, S, and N atoms were evenly distributed in the carbon skeleton, producing abundant heteroatomic functional groups. The sample with the largest specific surface area (SSA, 855.62 m2 g-1) was made at 900 °C without the addition of APS. With the increase in adding the ratio of APS, the SSA and pore volume of the sample were reduced, owing to the combination of APS and ZnO to form ZnS during the carbonization process, which inhibited the pore generation and activation effect of ZnO and damaged the pore structure of PC. At 0.5 A g-1 current density, PC900-1 (FR: ZnO: APS ratio 1:1:1, prepared at 900 °C) exhibited the maximum specific capacitance of 153.03 F g-1, whereas it had limited capacitance retention at high current density. PC900-0.1 displayed high specific capacitance (141.32 F g-1 at 0.5 A g-1), capacitance retention (80.7%), low equivalent series resistance (0.306 Ω), and charge transfer resistance (0.145 Ω) and showed good rate and energy characteristics depending on the synergistic effect of the double layer capacitance and pseudo-capacitance. In conclusion, the prepared FR-derived PC can meet the application of a supercapacitor energy storage field and realize the resource and functional utilization of biomass, which has a good application prospect.

Hierarchical porous nitrogen-doped carbon microspheres after thermal rearrangement as high performance electrode materials for supercapacitors

Porous carbon materials or activated carbons are characterized by their highly developed internal surface area and porosity. Especially the development of micro- and mesopore is of great importance. Many novel approaches to control such pore structure have been proposed. Among them, one of the most important and elegant techniques is the template carbonization method. So far many researchers have prepared novel porous carbons with the template technique using a variety of inorganic porous templates, such as layered clay, porous glass, silica gel, silica sol, zeolite and mesoporous silica. In this review, we introduce such template-mediated approach and highlight how useful and versatile the template technique is for the production of porous carbons.

Sodium metal-assisted carbonization of pyrrole to prepare N-doped porous carbons for high-rate performance supercapacitors

N/S dual-doped carbon materials were synthesized from coffee waste and cysteine for use as porous carbon electrode materials for electric double layer capacitors. The capacitance of the carbon materials was calculated from the experimental results of cyclic voltammetry and galvanostatic charge-discharge tests. The N/S-doped carbon materials obtained from heat-treatment with cysteine exhibited a higher discharge capacitance, 71.3 F/g, than that of the carbon without the cysteine treatment, 43.8 F/g, at 1 A/g. This is because the N/S dual-doped carbons possess a higher wettability than that of the other carbon material, even though the N/S doping with cysteine destroys the porous carbon structure, which reduces the BET surface area of the carbon samples. Elemental analysis was performed to determine the portions of nitrogen and sulfur elements doped into the carbon. From the XPS results, various states of nitrogen and sulfur elements were identified, and SEM/TEM images were obtained to observe their morphologies and porous structures.

Porous carbons are important cathode materials for metal-air batteries, but the most usual methods to prepare these porous structures are complex and of high cost. We have prepared porous carbons from bacterial cellulose (BC) hydrogels by a simple water-alcohol solvent exchange before carbonization. Alcohol treatment facilitates looser and more open structures than untreated BC, resulting in porous carbon structures with high surface area, appropriate for electrochemical applications. Used as cathodes in lithium-oxygen batteries, the carbon derived from 1-butanol treated BC has excellent discharge capacity (5.6 mA h cm−2) and good cycle life. This work presents a sustainable, straightforward and fast way to prepare porous carbon materials from BC.

The lithium sulfur battery is the one of the promising alternative rechargeable battery system to replace the conventional lithium ion battery system. It has a high capacity and energy density of 1,675 mA h g−1 and 2,500 Wh kg−1, respectively. The energy density is about five times higher compared to lithium ion batteries. Furthermore, sulfur is cheap, naturally abundant and safe . One of the main constraints is related to the poor electrical conductivity of sulfur which needs addition of high amount of conductive carbon, Another main problem is the high solubility of the intermediate polysulfides in the organic solvent electrolytes during discharge/charge process. Dissolved polysulfide components are moving back and forward between Li Anodes and Sulfur Cathodes, causing a rapid capacity loss and a low coulombic efficiency. The common approach to solve the problem was using the concept of sulfur encapsulation in the porous carbon structure. This strategy is the most popular study for cathodes in lithium sulfur battery in the last few years. It has been shown to solve the problems of low conductivity and dissolution of polysulfides simultaneously. As the results, the electrochemical performance of sulfur cathodes has been improved due the better electronic conductivity and the inhibation of polysulfide dissoltion. In this current works, biomass based porous carbons have been synthesized by using chemical activation of tropical salacca fruit peel with potassium carbonate and used as sulfur cathode component for lithium-sulfur batteries. The motivation was to obtain carbon with specific morphology and structures used for the application in composite sulfur cathodes for lithium sulfur battery. As shown by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption isotherms, the porous carbon material has microporous-mesoporous structures with honeycomb morphology. Composite sulfur cathode has shown a large initial discharge capacity of 802 mAh g−1 at current density of 0.1 C , which remained stable during 50 charge-discharge cycles . This stable and reversible cycleability of this composite cathode has been contributed by a unique combination of micro and mesoporosity, as well assurface functional groups, which could allow the retention of the intermediate polysulfides within the carbon porous structures, without enormous dissolution in the electrolyte.

Impact of aqueous and organic electrolytes on the supercapacitive performance of activated carbon derived from pea skin

Free-standing porous carbon nanofiber membranes obtained by one-step carbonization and activation for high-performance supercapacitors