Lithium electrochemical insertion

Letelher, M., ChevaUier, F., and Beguin, F. In situ Li NMR during lithium electrochemical insertion into graphite and a carbon/carbon composite. 

Lithium-ion cells operate during charge and discharge by a mechanism that involves the electrochemical insertion of lithium into, and extraction from, positive and negative electrode host structures. For example, in the well known Li tC6 / Li, tCo02 system, which is assembled in the discharged state, lithium ions are extracted from the metal oxide structure and... 

During electrochemical reduction (charge) of the carbon host, lithium cations from the electrolyte penetrate into the carbon and form a lithiated carbon Li rCn. The corresponding negative charges are accepted by the carbon host lattice. As for any other electrochemical insertion process, the prerequisite for the formation of lithiated carbons is a host material that exhibits mixed (electronic and ionic) conductance. 

Fig. 9.5 First cycles of the electrochemical lithium exchanges (insertion/removal) in compounds LigAISis (a) and Li2ZnGe (b).

Figure 4. Electrochemical insertion of lithium into vanadium diselenide, showing reaction of two lithium (reprinted with permission from ref 61, copyright 1978 Elsevier) (top) open-circuit potentials, (bottom) behavior on cycling at 2 mA/cm. ...

Small monovalent cations such as Li" or Cu" may be mobile in iron oxides at relatively low temperatures. This fact can provide an opportunity to prepare unusual compounds at low temperatures by either chemical or electrochemical insertion or extraction of lithium or copper. However, care must be taken in high-temperature preparations to prevent, for example, loss of Li as Li20 at high temperatures or disproportionation at low temperatures - especially at grain boundaries - into lithium-rich and lithium-poor phases. 

Leroux F, Metenier K, Gautier S, Frackowiak E, Bonnamy S, Beguin F. Electrochemical insertion of lithium in catalytic multi-walled carbon nanotubes. J Power Sources 1999 81-82 317-322. 

Shin HC, Liu M, Sadanadan B, Rao AM. Electrochemical insertion of lithium into multi-walled carbon nanotubes prepared by catalytic decomposition. J Power Sources 2002 112 216-221. 

There are two main kinds of rechargeable battery based on lithium chemistry the lithium-metal and the lithium-ion battery. In both the positive electrode is a lithium insertion material the negative in the former is lithium metal and in the latter it is a lithium insertion host. The reason for the application in lithium batteries of insertion electrode materials, which are electronic and ionic conductive solid matrixes (inorganic and carbon-based), is that electrochemical insertion reactions are intrinsically simple and highly reversible. 

The specific systems selected for this study are described later. The major problem of TCO is the first irreversible capacity loss, resulting from the reaction of lithium with SnO and the formation of Li20. Nevertheless, the development of TCO was the first demonstration of the potential for creating the so-called active-inactive nanocomposite anode materials by the electrochemical insertion of lithium into the tin oxide-based amorphous glass. 

Xia, Y, and Yoshio, M. 1996. An investigation of lithium ion insertion into spinel structure Li-Mn-O compounds. Journal ofthe Electrochemical Society 143, 825-833. 

In 1975, Whittingham was first to report the reversible electrochemical lithium intercalation into vanadium pentoxide [11]. V2O5 electrodes are expected to undergo lithium ion insertion accompanied by several structural modifications, occurring in several consecutive stages [21, 22]... 

Because of its relevance to batteries, the mechanism of lithium insertion into anatase Ti02 has been extensively studied. The electrochemical insertion/extraction of Li is believed to be driven by the accumulation of electrons in Ti02 electrodes in contact with Li -containing electrolytes, and the overall cell reaction can be written as... 

The crystalline structure of anatase is tetragonal (s.g. IT /amd] and contains distorted TiOg octahedra, which define a series of octahedral and tetrahedral vacant sites. These sites allow lithium uptake of 0.5 Li per formula unit, corresponding to a theoretical capacity of 168 mAh g [81]. A two-phase mechanism has been suggested to describe the electrochemical insertion of lithium... 

The insertion mechanism of the lithium ion into various kinds of carbons, when used as an anode in Li ion batteries has been extensively studied both experimentally and theoretically. However, the electrochemical insertion process is not yet fully understood. Polyparaphenylene (PPP)-based disordered carbon has a superior lithium storage capacity when used as an anode in the Li ion battery, and thus attracts much attention. In order to investigate the insertion mechanism of lithium into this material, the uptake and release processes of lithium were monitored by in situ Raman spectroscopy [90]. It was found that the band intensities of the characteristic peaks of disordered carbon decrease upon the discharging process and increase with the charging process, with quite good reversibility. Moreover, the frequency of the band related to the intraring C-C stretching mode of PPP at 1605 cm also... 

The effect does not seem to be related to thermodynamic barriers since the electrochemical insertion of lithium into common intercalation compounds, such as LiVaOs or VeOn, is an easily reversible process. In fact, electrochemical and spectroscopical studies carried out in liquid electrolytes have clearly demonstrated that these intercalation compounds can easily and repeatedly accept Li" ions without undergoing significant structure alterations. It has to be pointed out, however, that these studies have been carried out at low temperatures. Recent investigations performed at elevated temperatures (i.e. around 120°C) have indicated a crystalline to amorphous... 

The device by Corradini et al uses an ITO counter-electrode at which occurs, without significant colour change, an electrochemical process that is presumably due to lithium ion insertion and involves up to ca. 7.5mCcm [29]. Figure 7.7 shows the transmittance in the visible and IR regions of the electrochromic-electrode in the undoped and doped states as well as of the ITO counter-electrode before and after lithium insertion. 

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