Graphite lithium-intercalated

Billaud D., Henry F.X. and Willmann P. Electrochemical Synthesis of Binary Graphite-Lithium Intercalation Compounds. Mat. Res. Bull., 28, 477-483 (1993). 

Because of the variety of available carbons, a classification is inevitable. Most carbonaceous materials which are capable of reversible lithium intercalation can be classified roughly as graphitic and non-graphitic (disordered). 

Intercalation compounds of lithium and other species into the layered structure of graphite, synthesized by chemical methods, have been known for a long time. In the mid-1980s, the possibility of a reversible lithium intercalation from apro-tic solutions containing lithium salts into certain carbonaceous materials was discovered ... 

The intercalation compounds of lithium with graphite are very different in their behavior from intercalation compounds with oxides or halcogenides. Intercalation processes in the former compounds occur in the potential region from 0 to 0.4 V vs. the potential of the lithium electrode. Thus, the thermodynamic activity of lithium in these compounds is close to that for metallic lithium. For this reason, lithium intercalation compounds of graphite can be used as negative electrodes in batteries rather than the difficultly of handling metallic lithium, which is difficult to handle. 

Figure 4. Depiction of lithium intercalated into the carbon/graphite lattice.

Figure 17. The basal plane and prismatic surfaces of graphite have different functions with respect to lithium intercalation and de-intercalation (= charge, discharge, self-discharge, etc.). As a consequence, only the electrolyte decomposition product layers at the prismatic surfaces have SEIfunction. Any processes related with electrolyte decomposition product layers at the basal plane surfaces (= non-SEI layers) therefore can not be directly related to electrochemical data such as charge, discharge, self-discharge, etc. The situation is even more complex as the SEI composition and morphology at the basal and prismatic surface...

Due to its high energy density (3,860 mAh/g) and low voltage, lithium is the most attractive metal of the periodic table for battery application. Unfortunately lithium metal, and most of its alloys cannot be used in rechargeable batteries because of their poor cyclability. Therefore, lithium intercalation compounds and reversible alloys are among today s materials of choice for subject application. The most common active materials for the negative electrodes in lithium-ion battery applications are carbonaceous materials. The ability of graphitized carbonaceous materials to... 

Figure 6. The entropy of lithium intercalation into natural graphite, after [22],...

The source carbon materials show a significant electrochemical activity for lithium intercalation though the reversible capacity is relatively low and tends to reduce with cycling. For the thermally expanded graphite... 

Figure 11. (a) Initial IV2 cycles of a Li/petroleum coke cell. The cell was cycled at a rate of 12.5 h for Ax = 0.5 in Li sG6. (b) Initial IV2 cycles of a Li/graphite cell. The cell was cycled at a rate of 40 h for Ax= 0.5 in Li sG6. F denotes the irreversible capacity associated with SEI formation, E the irreversible capacity due to exfoliation, and I the reversible capacity due to lithium intercalation into carbon. 1.0 M LiAsEe in EC/PC was used as electrolyte. (Reproduced with permission from ref 36 (Eigure 2). Copyright 1990 The Electrochemical Society.)... 

In situ Raman spectra studies performed on graphite anodes also seem to reveal a cointercalation occurrence that leads to exfoliation. Huang and Freeh used solutions of LiC104 in EC/EMC and EC/DME as electrolytes and monitored the E2g2 band at 1580 cm in the Raman spectra of the graphite that was cycled between 2.0 and 0.07 Reversible lithium intercalation and deintercalation was indicated by... 

Figure 16. Voltage profiles for the first two lithium intercalation/deintercalation cycles realized on graphite anode in t-BC/EMC and c-BC/EMC solutions of 1.0 M LiPEe. (Reproduced with permission from ref 255 (Eigure 7). Copyright 2000 The Electrochemical Society.)...

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