Fluorinated-graphite-intercalation compound

Discharge characteristics of fluorine-graphite intercalation compounds... 

Fig. 6. Galvanostatic discharge curves of button-type cells Li/1 M L1CIO4 + EC PC DME/LT—CFV, HT—CF, at 40 mAg 1. LT—CFV fluorine-graphite intercalation compound prepared at a low temperature, HT—CFV graphite fluoride prepared at a high temperature (reproduced with permission from J. Power Sources, 68 (1994) 708 [34]).

Group 14. - 3.14.1 Carbon. The bonding structure in amorphous carbon nitride has been studied by H, and NMR spectroscopy. A F NMR study of paramagnetism in fluorinated graphite has been reported. Carbon-fluorine bonding has been detected in fluorine-graphite intercalation compounds by and F NMR spectroscopy. ... 

Touhara, H. Suganuma, S. Okino, F., "Lithium Batteries with Fluorine-Graphite Intercalation Compound Cathodes. Post-Graphite Fluoride Cathode," Tanso 1991,150, 328. 

Nakajima, T., "Fluorine-Graphite Intercalation Compounds. Their Synthesis, Structures, and Physical and Chemical Properties," Tanso, 1990,145,295. 

TABLE 12.3 Fluorine/carbon atomic ratio, stage number and repeat distance 4 of fluorine-graphite intercalation compounds synthesized by various methods [189-192]... 

Figure 1 Fully optimized structures of the partially fluorinated graphite intercalation compounds with optimized Hj molecules (Adapted with permission from Ref 27. Copyright (2009) American Chemical Society.)...

It is used as a fluorinating reagent in semiconductor doping, to synthesi2e some hexafluoroarsenate compounds, and in the manufacture of graphite intercalated compounds (10) (see Semiconductors). AsF has been used to achieve >8% total area simulated air-mass 1 power conversion efficiencies in Si p-n junction solar cells (11) (see Solarenergy). It is commercially produced, but usage is estimated to be less than 100 kg/yr. 

Dining interaction at ambient temperature in a bomb to produce poly (carbon monofluoride), admission of fluorine beyond a pressure of 13.6 bar must be extremely slow and carefully controlled to avoid a violently exothermic explosion [1], Previously it had been shown that explosive interaction of carbon and fluorine was due to the formation and decomposition of the graphite intercalation compound, poly (carbon monofluoride) [2], Presence of mercury compounds prevents explosion during interaction of charcoal and fluorine [3], Reaction of surplus fluorine with graphite or carbon pellets was formerly used as a disposal method, but is no longer recommended. Violent reactions observed when an exhausted trap was opened usually involved external impact on the metal trap, prodding the trap contents to empty the trap, or possibly ingress of moist air... 

During interaction at ambient temperature in a bomb to produce poly(carbon monofluoride), admission of fluorine beyond a pressure of 13.6 bar must be extremely slow and carefully controlled to avoid a violently exothermic explosion [ 1 ]. Previously it had been shown that explosive interaction of carbon and fluorine was due to the formation and decomposition of the graphite intercalation compound, poly(carbon monofluoride)... 

Katinonkul, W., Lerner, M. M., Graphite intercalation compounds with large fluoroanions. Journal of Fluorine Chemistry 2007,128, 332-335. 

If GO is used as a host lattice for Li+ in aprotic electrolytes, reversibility is improved [577]. The potential level is distinctly more positive than with donor GIC, at about —1 V vs. SHE. An all-solid-state Li/GO battery with PE0/LiC104 as solid electrolyte was reported by Mermoux and Touzain [578], but rechargeability is poor. Recently, the structure of graphite oxide was studied by its fluorination at 50-2()0 °C [579]. C-OH bonds were transformed into C-F bonds. The examples, in conjunction with Section 2, show that the formation or cleavage of covalent C-O (C-F) bonds makes the whole electrochemical process irreversible. Application was attempted in lithium primary batteries, which have a voltage of 2-2.5 V. Really reversible electrodes are only possible, however, with graphite intercalation compounds, which are characterized by weak polar bonds. 

We report results of first-principles molecular orbital calculations on model clusters of graphite (C24), alkali graphite intercalation compounds (MC48 M = Li, Na, K, Rb, Cs), fullerene (Ceo), and fluorinated fullerenes (CeoFa, x — 18, 36, 48). The calculated partial densities of states (pDOS) are compared with measured x-ray absorption near edge structure (XANES) spectra, x-ray photoelectron spectra (XPS), x-ray emission spectra (XES), and ultraviolet photoelectron spectra (UPS). In the case of graphite and its compounds, the calculated pDOS well reproduce features of the observed XANES and UPS spectra. The calculated pDOS and the observed XPS, UPS and XANES of CeoFx (x = 0, 36, 48) are also in satisfactory accordance. 

Carbon atoms crystallize in several forms. Graphite and diamond are well known carbon polymorphs. Fullerenes, which were discovered in the 1980 s, have also been well characterized. Carbon materials show a variety of different physical and chemical properties. Because of this the electronic structure of carbon materials has been investigated using a number of different experimental techniques, for example, XPS, UPS and XANES. Theoretical studies of carbon materials have been also performed. However, experimentally observed spectra are not always consistent with theoretical predictions. Recently, in order to understand the various kinds of observed electronic spectra, DV-Xa calculations have been performed on a small cluster model. [1] In the present paper, we report results of DV-Xa calculations performed on the carbon materials graphite, alkali graphite intercalation compounds (GIC), fullerene, and fluorinated fullerenes. 

Like the alkali metals, some halogens, particularly fluorine, form intercalated compounds with graphite crystals. Reaction usually starts at 600°C. However, graphite does not react with chlorine at temperatures below that of the electric arc. 

The addition of lithium fluoride, due to its solubility in a fluorine bath, can suppress the occurrence of the anode effect.2 Nakajima and co-workers reported that the carbon/hydrogen fluoride/fluorine system formed the graphite fluoride intercalation compound C4F as a solid... 

It is believed that the discharge mechanism involves the formation of an intermediate lithium intercalation compound in which both lithium and fluorine are situated between the carbon layers of the graphitic structure. The carbon formed is graphitic and improves the cell performance as the discharge progresses, leading to a high cathode utilization - close to 100% for low currents. The lithium fluoride precipitates. 

Vaknin, D., I. Palchan, D. Davidov, H. Selig, and D. Moses. 1986. Resistivity and E.S.R. studies of graphite HOPG/fluorine intercalation compounds. Synth. Metals 16 349-365. 

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