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The electrochemical behavior of porous carbons based on carbon fibers and those based on phenolic was evaluated by cyclic voltammetry via the Fe 2+ /Fe 3+ redox couple. An irreversible electrochemical response obtained from the fiber-based porous carbons was made reversible by coating of the porous carbons with graphite flakes or carbon black; the electron-transfer rate...
Electrochemical formation of graphite intercalation compounds (GICs) has been studied in the electrolyte with mixed sulfuric acid and acetic acid. The results show that, with addition of acetic acid, GICs can be synthesized in the electrolyte with sulfuric acid concentration as low as 3.6M, even though no GIC is formed in pure acetic acid. The stage structure of the synthesized GICs varies with the...
Oxidation changed the electrochemical behavior of carbon black, catalytically grown carbon filaments and pitch-based carbon fibers from irreversible to reversible, as shown by cyclic voltammetry using the Fe(CN) -3-46 redox couple. Thermal oxidation of carbon black (16%) yielded a higher electron transfer rate constant k s than did chemical (HCl or HNO 3 ...
A formic acid-graphite intercalation compound (HCOOH-GIC) has been successfully synthesized by an electrochemical process whereby formic acid solution serves as both the electrolyte and the intercalate source. Stage structures of 3, 4 and 5 have been revealed by both X-ray diffraction and Raman spectroscopy. Formation of HCOOH-GIC was achieved by controlling the apparent anodic current density in...
Hairy carbons were prepared by catalytic growth of carbon hairs (diameter 0.05-0.2 μm, at least partly crystalline) on carbon black, graphite particle and carbon fiber substrates. Of the substrates used, the most abundant hair growth was achieved using carbon black, due to the confinement of the catalyst size by the pores in the carbon black. The cyclic voltammetric response of all hairy carbons...
Two iron-carbon composites were prepared from ferrocene-polymer mixtures with resol resin (Fe-RESOL) or epoxy resin (Fe-EPOXY), and they were compared with the previous composite (Fe-PFA) made from a ferrocene-poly(furfuryl alcohol) mixture from structural and the electrochemical viewpoints. The features of the composites were divided into two groups, that is, a group consists of Fe-PFA and Fe-RESOL...
Electrochemical synthesis of FeCl 3 -graphite intercalation compounds (GICs) in aqueous solution was studied by chronoamperometric, chronopotentiometric and cyclic voltammetric methods. Using 6-10m FeCl 3 -aqueous solutions, FeCl 3 -GICs with stage 2-6 and/or mixed stage structures were synthesized by an anodic oxidation, evidenced by both X-ray diffraction patterns and Raman...
The electrochemical intercalation of lithium into graphite was studied in various electrolytes containing chloroethylene carbonate (ClEC), ethylene carbonate (EC) and propylene carbonate and their mixtures as solvents and LiClO 4 , LiBF 4 and LiAsF 6 as lithium salts. The reduction of ClEC and EC, catalyzed on the surface of the graphite electrode, starts at potentials equal...
Anodic performances of cokes derived from a series of coals with variable ranks were examined in a Li-ion secondary battery by carbonizing at 700 and 1000°C under normal, pressurized and co-carbonized conditions. The coke carbonized at 700°C exhibited discharge at 0.12–0.8V and 0.8–1.25V vs Li/Li + which were reversible too and much higher than the charge potentials, respectively. The capacity...
Multiwalled carbon nanotubes (MWNT) have been obtained by catalytic decomposition of acetylene at 900°C over silica supported cobalt. The thermal treatment at 1600, 2000 and 2800°C allowed improvement of their structural and microtextural organization as well as the elimination of any remaining nanoparticles of cobalt. Such a tubular carbon host with graded texture and chemical composition is a very...
The anodic performances of anisotropic carbon derived from quinoline pitch (CQP) to be used in the lithium ion battery were studied to clarify the influence of nitrogen in the carbon hexagonal sheet. The quinoline pitch was synthesized by using HF/BF 3 as a catalyst. Nitrogen in the carbon existed as pyridinic, pyrrolic and quaternary types to be converted in this sequence, depending upon...
The recent development of lithium rechargeable batteries results from the use of carbon materials as lithium reservoir at the negative electrode. Reversible intercalation, or insertion, of lithium into the carbon host lattice avoids the problem of lithium dendrite formation and provides large improvement in terms of cycleability and safety. This paper reviews the main achievements on performance and...
Fullerene-doped glassy carbons were prepared by co-polymerizing diethynylmethanobuckminsterfullerene with 1,3-diethynylbenzene and phenylacetylene, followed by carbonization at 600°C. The materials were characterized by FTIR and cyclic voltammetry, which indicated that a fullerene-like species survives the heat treatment. The chemical reactivity of the fullerene-doped low-temperature glassy carbon...
The structures and anode performance of graphitized and boron-doped milled mesophase pitch-based carbon fibers (mMPCFs) have been comparatively studied and the results obtained by X-ray diffraction (XRD), SEM, Raman spectroscopy and electrochemical measurements are discussed. The boron doping at the level of 2.66 at.% (2.4 wt.%) enhances the growth of the crystallite thickness, L c(002) ,...
To influence the material properties of carbon fiber reinforced thermoplastics, basic carbon fiber surfaces were produced by heating fibers at 905 o C under nitrogen, cooling to 25 o C and exposing them to oxygen. Pure oxygen as well as air were used at different temperatures. Zeta (ζ)-potential (ζ=f(c, pH)) measurements confirmed the existence of basic surface functionalities on most...
Mesocarbon Microbeads (MCMB) carrying five different types of hexagon alignment, parallel, deformed onion-like, longitude-like, longitude-like with disclination, and Brooks/Taylor (latitude-like) were prepared and examined in their performances as an anode of a Li-ion battery. The first two beads were prepared from naphthalene isotropic pitch without any inert materials, and the next two were from...
Boron-substituted carbons have been produced by chemical vapour deposition from acetylene and boron trichloride precursors at 1140°C. Li intercalation was investigated, chemically from the Li vapour and electrochemically in Li–carbon cells. In both cases, the amount of intercalated Li increases with the boron content of the carbon, up to a value of 13 at.% boron. Above this value, the intercalation...
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