High temperature carbon–carbon supercapacitor using ionic liquid as electrolyte

This paper presents results about the electrochemical and cycling characterizations of a supercapacitor cell using a microporous activated carbon as the active material and N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) ionic liquid as the electrolyte. The microporous activated carbon exhibited a specific capacitance of 60 F g−1 measured from the three-electrode cyclic voltammetry experiments at 20mVs−1 scan rate, with a maximum operating potential range of 4.5V at 60 ◦C. A coin cell assembled with this microporous activated carbon and PYR14TFSI as the electrolyte was cycled for 40,000 cycles without any change of cell resistance (9cm2), at a voltage up to 3.5V at 60 ◦C, demonstrating a high cycling stability as well as a high stable specific capacitance in this ionic liquid electrolyte. These high performances make now this type of supercapacitor suitable for high temperature applications (≥60 ◦C)

Large scale production of multi-walled carbon nanotubes by fluidized bed catalytic chemical vapor deposition : a parametric study

A parametric study investigating the impact of temperature, run duration, total pressure, and composition of the gaseous phase on the catalytic growth of multi-walled carbon nanotubes (MWNT) has been performed. MWNT have been produced very selectively on the multi gram scale by catalytic chemical vapor deposition from ethylene in a fluidized bed reactor. The kinetics of MWNT growth is fast and, with the catalyst used, no induction period has been observed. The kinetic law is positive order in ethylene concentration and the process is limited by internal diffusion in the porosity of the catalyst. The formation of MWNT in the macroporosity of the catalyst induces an explosion of the catalyst grains. Such a process, thanks to the absence of temperature gradient and to the efficient mixing of the grains allows a uniform and selective treatment of the catalyst powder leading to very high selectivity towards MWNT formation. High purity MWNT have been obtained after catalyst dissolution. Depending on the temperature of production, the specific surface area of this material ranged between 95 and 455 m2/g

An original growth mode of MWCNTs on alumina supported iron catalysts

Multi-walled carbon nanotubes (MWCNTs) have been produced from ethylene by Fluidized Bed Catalytic Chemical Vapor Deposition (FB-CCVD) on alumina supported iron catalyst powders. Both catalysts and MWCNTs-catalyst composites have been characterized by XRD, SEM-EDX, TEM, Mössbauer Spectroscopy, TGA and nitrogen adsorption measurements at different stages of the process. The fresh catalyst is composed of amorphous iron (III) oxide nanoparticles located inside the porosity of the support and of a micrometric crystalline &-iron (III) oxide surface film. The beginning of the CVD process provokes a brutal reconstruction and simultaneous carburization of the surface film that allows MWCNT nucleation and growth. These MWCNTs grow aligned between the support and the surface catalytic film, leading to a uniform consumption and uprising of the film. When the catalytic film has been consumed, the catalytic particles located inside the alumina porosity are slowly reduced and activated leading to a secondary MWCNT growth regime, which produces a generalized grain explosion and entangled MWCNT growth. Based on experimental observations and characterizations, this original two-stage growth mode is discussed and a general growth mechanism is proposed

Activated carbon–carbon nanotube composite porous film for supercapacitor applications

Activated carbon/carbon nanotube composite electrodes have been assembled and tested in organic electrolyte (NEt4BF4 1.5 M in acetonitrile). The performances of such cells have been compared with pure activated carbon-based electrodes. CNTs content of 15 wt.% seems to be a good compromise between power and energy, with a cell series resistance of 0.6 Ω cm2 and an active material capacitance as high as 88 F g−1

Unexpected Rift Valley Fever Outbreak, Northern Mauritania

During September–October 2010, an unprecedented outbreak of Rift Valley fever was reported in the northern Sahelian region of Mauritania after exceptionally heavy rainfall. Camels probably played a central role in the local amplification of the virus. We describe the main clinical signs (hemorrhagic fever, icterus, and nervous symptoms) observed during the outbreak

Equations of state with group contribution binary interaction parameters for calculation of two-phase envelopes for synthetic and real natural gas mixtures with heavy fractions

YesThree equations of state with a group contribution model for binary interaction parameters were employed to calculate the vapor-liquid equilibria of synthetic and real natural gas mixtures with heavy fractions. In order to estimate the binary interaction parameters, critical temperatures, critical pressures and acentric factors of binary constituents of the mixture are required. The binary interaction parameter model also accounts for temperature. To perform phase equilibrium calculations, the heavy fractions were first discretized into 12 Single Carbon Numbers (SCN) using generalized molecular weights. Then, using the generalized molecular weights and specific gravities, the SCN were characterized. Afterwards, phase equilibrium calculations were performed employing a set of (nc + 1) equations where nc stands for the number of known components plus 12 SCN. The equations were solved iteratively using Newton's method. Predictions indicate that the use of binary interaction parameters for highly sour natural gas mixtures is quite important and must not be avoided. For sweet natural gas mixtures, the use of binary interaction parameters is less remarkable, however