Graphites lithium-graphite intercalation compounds

The first lithiated graphitic carbons (lithium-graphite intercalation compounds, abbreviated as Li-GIC s),... 

Billaud D., Henry F.X., Lelaurain M., and Willmann P. Revisited Structures of Dense and Dillute Stage II Lithium-Graphite intercalate Compounds. J. Phys. Chem Solids, 57, 775-781 (1996). 

Ohno, T. 1980. Electronic band structure of lithium-graphite intercalation compound C6Li../. Phys. Soc. Jpn. 49(Suppl. A) 899-902. 

Morkovich, V. Z. 1996. Synthesis and XPS investigation of superdense lithium-graphite intercalation compound, LiC2. Synth. Metals 80 243-247. 

Delhaes P, Manceau KP, Guerard D. Physical properties of first and second stage lithium graphite intercalation compounds. Synth Met 1980 2 277-284. 

Ohzuku T, Iwakoshi Y, Sawai K. Formation of lithium-graphite intercalation compounds in nonaqueous electrolytes and their application as a negative electrode for a lithium ion (shuttlecock) cell. J Electrochem Soc 1993 140 2490-2498. 

Group 1. - 7Li NMR spectroscopy was used to characterise a lithium/ graphite intercalation compound with a formula close to LiC 1 In situ solid-state 7Li NMR data were reported for lithium inserted into disordered carbon. There was evidence for both Lis+ and metallic lithium species.2 7Li and 13C solid-state NMR spectra were used to characterise a mesoporous tantalum oxide lithium fulleride (Ceo) composite material.3... 

Another important feature for lithium graphite intercalation compounds in Li -containing electrolytes is the formation of solid electrolyte interface (SEI) film. During the first-cycle discharge of a lithium/carbon cell, a part of lithium atoms transferred to the carbon electrode electrochemically will react with the nonaque-ous solvent, which contributes to the initial irreversible capacity. The reaction products form a Lb-conducting and electronically insulating layer on the carbon surface. Peled named this film as SEI. Once SEI formed, reversible Lb intercalation into carbon, through SEI film, may take place even if the carbon electrode potential is always lower than the electrolyte decomposition potential, whereas further electrolyte decomposition on the carbon electrode will be prevented. 

Eunabiki A, Inaba M, Abe T, Ogumi Z (1999) Nucleation and phase-boundary movement upon stage transformation in lithium-graphite intercalation compounds. Electrochim Acta 45 865... 

Using dilatometry in parallel with cyclic voltammetry (CV) measurements in lmolL 1 LiC104 EC-l,2-dimethoxy-ethane (DME), Besenhard et al. [87] found that over the voltage range of about 0.8-0.3 V (vs. Li/Li+), the HOPG crystal expands by up to 150 percent. Some of this expansion seems to be reversible, as up to 50 percent contraction due to partial deintercalation of solvated lithium cations was observed on the return step of the CV. It was concluded [87] that film formation occurs via chemical reduction of a solvated graphite intercalation compound (GIC) and that the permselective film (SEI) in fact penetrates into the bulk of the HOPG. It is important to repeat the tests conducted by Besenhard et al. [87] in other EC-based electrolytes in order to determine the severity of this phenomenon. 

In fact, crystalline graphites usually cannot be operated in PC electrolytes, unless effective film forming electrolyte additives are used (see above) as propane gas evolution [35], creation of solvated graphite intercalation compounds (sGICs) [36], and graphite exfoliation take place. Recently [37, 38], it was found that propylene evolution is observed at graphite, while absent at lithium active metallic anodes, e.g., Sn and SnSb. 

It has been known since the mid 1950s that graphite can form intercalation compounds with lithium ions, which are accommodated in the interstitial region between the planar graphene sheets. ° The most lithium-enriched intercalation compound of this family has a stoichiometry of LiCe, and its chemical reactivity is very similar to that of lithium metal. There have been a number of different chemical approaches to the preparation of these compounds, for example, by direct reactions of graphite with molten lithium at 350 with... 

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