Carbonate Additives

The preparation of methylene ethylene carbonate and the incorporation of methylene ethylene carbonate into lithium-ion batteries as an electrolyte additive have been described (53). 

The addition of low concentrations of methylene ethylene carbonate of 1-2% to 1 M LiPF6 in 3 7 ethylene carbonate/e yl methyl carbonate improves the capacity retention of lithium-ion batteries cycled at an elevated temperature of 60°C. 

XPS and Fourier transform infrared spectroscopy (FTIR) measurements of the electrodes indicated the presence of poly(meth-ylene ethylene carbonate) on the anode siuface. The modification of the anode solid electrolyte interphase correlates with significant improvements in the cycling performance at 60°C (53). 

In silicone electrodes, a factor that affects the cell performance is the formation of a solid electrolyte interface layer on the sUicon surface (47). Initially, the surface of the silicon material has a thin native oxide layer on it which has a low conductivity. During the first charge, this layer is replaced by a solid electrolyte interface layer of higher ionic conductivity formed from reactions with the electrolyte and reduction of the solvents. 

The solid electrolyte interface can be composed of various different products, for example, Li2C03, LiF, Li20, lithium alkyl carbonates, pol5mieric hydrocarbons and others. Each product will start forming at different stages of the charging process, depending on the anode potential. 

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The one-carbon addition we used in frames 98 and 101 is all right if we just want to add an activating group to a readily available ketone, but is not otherwise good synthetic practice ... 

Lithium carbonate addition to HaH-Heroult aluminum ceU electrolyte lowers the melting point of the eutectic electrolyte. The lower operating temperatures decrease the solubiHty of elemental metals in the melt, allowing higher current efficiencies and lower energy consumption (55). The presence of Hthium also decreases the vapor pressure of fluoride salts. 

Ahyl alcohol undergoes reactions typical of saturated, aUphatic alcohols. Ahyl compounds derived from ahyl alcohol and used industriahy, are widely manufactured by these reactions. For example, reactions of ahyl alcohol with acid anhydrides, esters, and acid chlorides yield ahyl esters, such as diahyl phthalates and ahyl methacrylate reaction with chloroformate yields carbonates, such as diethylene glycol bis(ahyl carbonate) addition of ahyl alcohol to epoxy groups yields products used to produce ahyl glycidyl ether (33,34). 

Steel is essentially iron with a small amount of carbon. Additional elements are present in small quantities. Contaminants such as sulfur and phosphorus are tolerated at varying levels, depending on the use to which the steel is to be put. Since they are present in the raw material from which the steel is made it is not economic to remove them. Alloying elements such as manganese, silicon, nickel, chromium, molybdenum and vanadium are present at specified levels to improve physical properties such as toughness or corrosion resistance. 

In the second step, the activated surface-carbon radical reacts with the carbon-hydrogen species (acetylene as a monomer unit) in the gas phase to become the site for carbon addition ... 

That it is not entirely negligible, however, is indicated by the fact (demonstrated by structure studies see Chap. VI) that radical addition occurs preferentially—presumably at the unsubstituted carbon. Addition at the substituted carbon would yield a radical on the unsubstituted carbon hence the substituent would be without effect. 

Summarizing the above, it may be stated that activated carbons and pseudocapacitive materials in EC electrode structure are responsible for the energy storage parameters (specific energy), while non-active highly conductive carbon additives are responsible for the electrode internal resistance (EC specific power). 

More interesting data was found in the mixtures we have seen that carbon additives tend to reduce specific resistance of the mixture, while active material (activated carbon) increases resistance (54 10"3 ohm-m vs. 49 10"3 ohm-m). This phenomenon suggests that carbon-carbon component mixtures have better packing characteristics. 

Catalysts from active carbon additionally activated with cobalt- or iron- phthalocyanines are also studied [7], The results show that at current densities up to 50 mA/cm2, the polarization of the air electrodes with catalyst from active carbon promoted with FePc is lower than that of the electrode with catalyst from active carbon promoted with CoPc. At higher current density the polarization of the electrode with catalyst from active carbon promoted with CoPc is lower, which is probably connected to the lower transport hindrances, due to the more favorable structure of this catalyst. 

In the paper from V. Matveyev of the Ukrainian State University of Chemical Engineering, an examination of the role of conductive carbon additives in a composite porous electrode is conducted. A model for calculation of the local electrochemical characteristics of an electrode is presented. A comparison on the polarization of the electrode as a function of the redox state of the electroactive species is emphasized in the model. The electrochemical reaction of chloranil (tetrachlorobenzoquinone) was measured and results compare favorably to calculations derived from the model. 

MODELING OF ELECTROCHEMICAL PROCESSES IN THE ELECTRODES BASED ON SOLID ACTIVE REAGENTS AND CONDUCTIVE CARBON ADDITIVES... 

Sayama, K. and Arakawa, H., Significant effect of carbonate addition on stoichiometric photodecomposition of liquid water into hydrogen and oxygen from platinum-titanium (IV) oxide suspension,/. Chem. Soc., Chem. Commun., 150,1992. 

Fig. 8.7 Landscape position influence on annual carbon additions from 1995 to 2003 (Clay et al. 2005)...

Ceeen, F., Erdineler, A., Kilie, E. 2003. Effeet of powdered aetivated carbon addition on sludge dewaterability and substrate removal in landfill leachate treatment. Advances Environ Res 7 707-713. 

Kargi, E., Pamukoglu, M.Y. 2004b. Repeated fed-batch biological treatment of pre-treated landfill leachate by powdered activated carbon addition. Enzyme Microbial Technol 34 422 28. 

Sayama, K., Arakawa, H. 1996. Effect of carbonate addition on the photocatalytic decomposition of liquid water over aZrO, catalyst. J Photochem Photobiol A Chem 94 67-68. 

Osantowski, R.A. Dempsey, C.R. Dostal, K.A. Enhanced COD removal from pharmaceutical wastewater using powdered activated carbon addition to an activated sludge system. Proceeding of the 35th Industrial Waste Conference, Purdue University, West Lafayette, IN, 1980 719-727. 

All the examples described in the previous section involve the addition of hetero-nudeophiles, such as alcohols and amines, to the vinylidene carbon. Addition of... 

Addition of Nucleophiles Addition of Electrophiles to Ring Carbon Addition of Electrophiles to Ring Nitrogen... 

The city of Columbus, Ohio, installed a PACT water treatment system for 1.2 million. The system was purchased to remove atrazine (a pesticide) from the water supply. In 1997, Columbus spent 150,000 on powered activated carbon. Additional monitoring costs were estimated to be over 10,000 per year (D19947H, p. 11). 

From the understanding, provided by the calculations, of the mechanism by which lb cyclizes, what can be predicted about how the rate of this reaction might be affected by substituents on the benzene ring The substiment effects would, in fact, be expected to be small, except for possible steric effects due to substituents in the ortho positions. If both ortho positions are substimted, one would expect to see a decrease in rate, relative to unsubstituted lb. On the other hand, if only one ortho position is substituted, cyclization should be about as fast as in unsubstituted lb but cyclization should preferentially occur at the unsubstituted ortho carbon. Additional (8/8)CASPT2/6-31G calculations by Bill Kamey in our group and subsequent experiments by the Platz group confirmed these qualitative predictions about the effects of ortho substituents. 

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