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A high areal sulfur loading in a carbon-based cathode together with a high cell capacity is key to the design of lithium-sulfur batteries guaranteeing a superior energy density for use. However, a high sulfur loading produced using traditional blade coating techniques results in many technical issues such as sluggish electron/ion transport kinetics and cracking of the electrodes. Here a well designed...
Lithium–sulfur (LiS) battery, as a high energy-density storage system, has attracted great attention for next generation rechargeable battery applications. However, the fast capacity decay caused by lithium polysulfides (LiPSs) dissolution impedes its prospect for commercialization. In this work, nitrogen-doped graphene, as a chemical immobilizer, was designed to bind LiPSs and stabilize sulfur in...
Lithium-sulfur (Li-S) batteries are one of the most promising next-generation secondary battery systems for meeting increasing energy storage demands due to their high theoretical energy density. However, the commercialization of Li-S batteries is hindered by the low electrical conductivity of sulfur and the severe polysulfide shuttling problem. Here, we report the easy synthesis of a nitrogen-doped...
We have systematically investigated the structural and magnetic properties of N-doped graphene oxide by density-functional theory. Our results reveal that both the magnetic properties and the defect stability can be significantly affected by the bonding environment. Graphitic N defect has higher formation energy than both pyridinic and pyrrolic N defects. The pyrrolic N becomes more stable when its...
Microstructural defects (MSDs) in graphene are a primary negative factor for the crystal quality and electrical properties of graphene and there is little knowledge about their formation. Here we report the formation mechanism of MSDs in graphene domains during the CVD growth on Cu substrate. Hydrogen-etching results show that an etched graphene hole corresponds to the position of a MSD that appears...
An efficient membrane for helium separation from natural gas is quite crucial for cryogenic industries. However, most experimentally available membranes fail in separating helium from small molecules in natural gas, such as H2, as well as in 3He/4He isotopes separation. Using first-principles calculations, we theoretically demonstrated that the already-synthesized graphitic carbon nitride (g-C3N4)...
Percolating carbon nanoparticles were added into electrolyte to improve the performance of Li–S batteries. These percolating carbon nanoparticles acted as dispersible nanosized electrodes, allowed the direct electrochemical utilization of dissolved polysulfides in electrolyte, and mitigated the polysulfide shuttle. As a result, the polysulfide utilization was improved with the virtual sulfur capacity...
A series of carbon fiber (CF)/polyether polyurethane (PU) composites were prepared by in situ polymerization and a casting compression molding technique. The influence of CF content and its pretreatment with a coupling agent and oxidation by 65%-68% (mass fraction) nitric acid on the mechanical performance, thermal properties and morphology of the composites was investigated by TGA, SEM and mechanical...
A hybrid cathode material for high rate lithium ion batteries was prepared by ball-milling and spray-drying a slurry containing LiFePO4 nanoparticles, glucose and carbon nanotubes (CNTs) in water, followed by pyrolysis at 600°C for 6h under a gas mixture of 5% H2in Ar. CNTs with a large aspect ratio form a continuous conductive network connecting the LiFePO4 nanoparticles and amorphous carbon, which...
We fabricated a monolithic Fe 2 O 3 /graphene hybrid directly by hydrothermal reaction of ferrous oxalate dihydrate and graphene oxide without using a reducing agent. The reduced graphene oxide formed an interconnected network structure that can be used as a support for homogeneous distribution of active Fe 2 O 3 nanoparticles. The graphene network and the pore channels...
Multi-wall carbon nanotubes (MWCNTs) prepared by chemical vapor deposition, were pretreated by ball milling, chemical activation and ammoxidation and the influence of the pretreatment on their electrochemical capacitance was investigated. Results show that MWCNTs can be shortened and broken by ball milling and chemical activation, and as a result their surface area and pore volume are increased. However,...
Natural graphite was leached under microwave irradiation by acid mixtures containing HCl (12M) and HNO 3 (16M). It was found that the purification efficiency was affected by microwave power, reaction pressure, reaction time and the acid ratio. The carbon content of the graphite increased from 95.84% to 99. 43% under optimized leaching conditions with an acid volume ratio of 1:1, pressure of...
The topological microstructure of micro-coiled carbon fibers (MCFs) before and after high temperature treatment (HTT) was explored and characterized. Results suggested that as-grown MCFs had an annular ring-like structure in the cross section and a herringbone-like structure in the longitudinal section, but the orientation range of graphitic domains was wide. After HTT, the coiled fibers consisted...
Graphene oxide–carbon fiber/phenolic resin, chemically-reduced graphene oxide–carbon fiber/phenolic resin, and thermally-reduced graphene oxide–carbon fiber/phenolic resin composites were prepared by blending a graphene oxide suspension in an ethanol solution of phenolic resin with carbon fibers, followed by vacuum drying and hot pressing. The effects of the type of graphene oxide on structure, compressive...
Graphite nanosheets (GNSs) decorated with Fe 3 O 4 nanoparticles were synthesized by an inverse coprecipitation method. The Fe 3 O 4 –GNS hybrid material was characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption/desorption isotherms, thermogravimetry...
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