Intercalation material

In the lithium-ion approach, the metallic lithium anode is replaced by a lithium intercalation material. Then, tw O intercalation compound hosts, with high reversibility, are used as electrodes. The structures of the two electrode hosts are not significantly altered as the cell is cycled. Therefore the surface area of both elecftodes can be kept small and constant. In a practical cell, the surface area of the powders used to make up the elecftodes is nomrally in the 1 m /g range and does not increase with cycle number [4]. This means the safety problems of AA and larger size cells can be solved. 

A. H rold, Crystallo-chemistry of carbon intercalation compounds, in Intercalated Materials (Ed. F. Levy), D. Reidel, Dordrecht,... 

If an anodically colored electrochromic material (e.g., Ir02) is used as one electrode in the device in Eig. 33.1fi and a cathodically colored (e.g., WO3) is used as the other electrode, a much larger change in transmission per charge supplied can be seen compared to the case when only one electrode is electrochromic. Also, the use of an intercalation material as the counter electrode may be advantageous for the device shown in Eig. 33.1a, as it can minimize undesired reactions on the counter electrode. 

The microtubular electrode concept described here also offers another possible advantage. In these concentric tubular electrodes, each particle of the Li intercalation material (the outer tube) has its own current collector (the inner metal microtubule). This could be an important advantage for Li+ intercalation materials with low electrical conductivity. This advantage was not demonstrated here because TiS2 has relatively high electronic conductivity. We have recently shown that electrochemical synthesis can be used to coat the gold microtubular current collector with outer mbes of a... 

Li+ intercalation material (V. M. Cepak and C. R. Martin, unpublished). These results, which will be the subject of a future paper, show that other synthetic methodologies, in addition to CVD, can be used to make micro-structured battery electrodes like those described here. In addition, the underlying microtubular current collector does not have to be Au. Microtubules composed of graphite [35] or other metals [1,3] (e.g., Ni) could be used. Finally, for the advantages noted above to be realized in practical cells, large-scale template-fabrication methods would have to be developed. 

Lithium intercalation in VeOis has been studied by Stallworth et al. ° Variable-temperature Li NMR indicated considerable mobility for Li+ in the intercalated materials. The Li NMR data were compared with ESR spectra and near-edge X-ray absorption fine structure (NEXAFS) data on the same materials, and a correlation between vanadium oxidation state (from NEXAFS data) and NMR shift was observed. The authors explained the shifts in terms of different coupling mechanisms between the and shifts. The shifts were, however, extracted from static NMR experiments, and it is possible that some of the different local environments, typically revealed in a MAS spectrum, were not seen in this study. 

The intercalation capability of clay mineral decreases with increasing molecular volume of intercalated material [119]. The speed of intercalation of the MFA molecule decreases with increasing number of defects in the structure of mineral [120]. It corresponds with results of the study of Frost and coworkers [121] where highly ordered kaolinites easily intercalate which is in notable difference with high disordered kaolinites. The intercalation of formamide into kaolinite results in the changes in the vibrational spectra of both kaolinite and the target molecule [122-126]. The FA-intercalated kaolinite remains expanded after formamide desorption with a d(001) spacing of 10.09A [127-129]. 

Property Intercalation Material Nonfaradic Activated Carbon... 

From the Li-ion battery technology, it is known that carbons can be intercalated at more negative potentials than any other Li-intercalation material (see Figure 8.30). In commercial Li-ion batteries, two kinds of carbon materials are mainly used as negative electrode (1) nongraphitizable or hard carbons (HCs) and (2) graphite. 

Aranda, P. and Ruiz-Hitzky, E. Poly(ethylene oxide)-silicate intercalation materials, Chem. Mater. (1992), 4, 1395-1403. 

Fig. 14). The DNA-immobilized columns effectively accumulated more DNA-intercalating materials than the planar DNA films. The DNA-immobilized columns bound endocrine disruptors with a planar structure, such as dioxins, and benzo[a]pyrene. Bisphenol A and diethylstilbestrol, which lack a planar structure, did not bind to the DNA-coated columns. Table 1 shows the selective adsorptions of the insoluble DNA-based materials. 

With vapor-phase intercalation, the host is much less likely to decompose as just described. The disadvantage of vapor-phase intercalation is that with far fewer molecules impinging on the surface of the host, reaction rates are much slower. The disadvantage can also be an advantage since the reduced reaction rate allows the intercalated material to remain more homogeneous with respect to the amount of material intercalated. 

A LiAl-LDH intercalated with 4-nitrohippuric acid has been shown to exhibit second harmonic generation -532 nm radiation from incident 1064 nm [142]. It was reported that the ability of the intercalated material to exhibit non-linear optical properties is due to a perpendicular monolayer packing of the acid molecules in the interlayer. Such an orientation leads to an ordered arrangement of dipoles, giving rise to a bulk dipole moment in the solid. Crystals of the pure acid exhibit no frequency-doubling characteristics due to a centrosymmetric packing in the crystal. 

It has been shown that electroactive polymer films on electrodes can mediate electron transfer for metal deposition (9-11). Haushalter and Krause (5) have described the treatment of PMDA-ODA films with highly reactive Zintl complexes (e.g., Sn9 4, SnTe4 4) to yield an intercalated material able to reduce ions of platinum, palladium and silver at the film surface. Mazur et al., (12) reported the deposition of conductive Ag, Cu, and Au metal interlayers within a PMDA-ODA film by electrochemical reduction. 

In the last decade an abundant literature has focused more and more on the properties of low-symmetry systems having large unit cells which render unwieldy the traditional description in terms of the Bloch theorem. Low-symmetry systems include compUcated ternary or quaternary compounds, man-made superlattices, intercalated materials, etc. The k-space picture becomes totally useless for higher degrees of disorder as exhibited by amorphous materials, microcrystallites, random alloys, phonon-induced disorder, surfaces, adsorbed atoms, chemisorption effects, and so on. 

Graphite intercalate compounds have been known for some but their possibilities as catalysts have been explored comparatively recently. Their catalytic activities obviously depend on the nature of the intercalated material, and a range of graphite intercalates has been identified (see Table 3),... 

The structure of the intercalates are of considerable interest, in that the intercalate material enters the graphite layers to form in the final analysis, a one-to-one graphite-intercalate layer structure. Intermediate compounds involve inclusion of the material in, for example, a second, fourth, or fifth layer rather than dilution of the amount in the same layer. The chemical bonding in the compounds appears to be ionic and certainly involves electron transfer probably, for example, from potassium to the upper pi-band of graphite. ... 

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