Intercalation/deintercalation

Different investigations of the mechanisms of capacity degradation during cycling show that one of the main reasons of this degradation is significant change (by a factor of 3-4) in AM volume on the intercalation-deintercalation of lithium, followed by AM destruction [2-3],... 

This may lead to the irreversible changes in the material, caused by partial oxidation of graphite, loss of reversibility of the system along with the efficiency of reaction for intercalation-deintercalation (1). 

Chemical relaxation methods can be used to determine mechanisms of reactions of ions at the mineral/water interface. In this paper, a review of chemical relaxation studies of adsorption/desorption kinetics of inorganic ions at the metal oxide/aqueous interface is presented. Plausible mechanisms based on the triple layer surface complexation model are discussed. Relaxation kinetic studies of the intercalation/ deintercalation of organic and inorganic ions in layered, cage-structured, and channel-structured minerals are also reviewed. In the intercalation studies, plausible mechanisms based on ion-exchange and adsorption/desorption reactions are presented steric and chemical properties of the solute and interlayered compounds are shown to influence the reaction rates. We also discuss the elementary reaction steps which are important in the stereoselective and reactive properties of interlayered compounds. 

The fast reactions of ions between aqueous and mineral phases have been studied extensively in a variety of fields including colloidal chemistry, geochemistry, environmental engineering, soil science, and catalysis (1-6). Various experimental approaches and techniques have been utilized to address the questions of interest in any given field as this volume exemplifies. Recently, chemical relaxation techniques have been applied to study the kinetics of interaction of ions with minerals in aqueous suspension (2). These methods allow mechanistic information to be obtained for elementary processes which occur rapidly, e.g., for processes which occur within seconds to as fast as nanoseconds (j0. Many important phenomena can be studied including adsorption/desorption reactions of ions at electri fied interfaces and intercalation/deintercalation of ions with minerals having unique interlayer structure. 

The benefit of a hybrid phase for the intercalation-deintercalation of mobile species such as Li+ cations is well illustrated by the study of conductive polymers such as polyaniline or polypyrrole intercalated into a V2O5 framework as potential electrode materials in lithium batteries [34]. For PANI/V2O5, an oxidative post-treatment performed under an oxygen atmosphere allowed the authors to compare the conductivity attributed to the polymer, as in absence of reduced cations, there was no electronic hopping between ions, and the conductive state was due only to the... 

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.)...

Finally, NMR has also be used to study other spinels materials that do not contain manganese. For example, the intercalation/deintercalation of lithium titanate spinels such as Li4/3+Ji5/304 and Lii.i-Tii.904+a have been investigated. These materials may be used as anode materials in combination with cathodes operating at 4 V (vs Li) to produce cells with potentials of ca. 2.5 V. These materials are either diamagnetic or metallic, and unlike the mangan-ates, only very small differences in shifts are seen for Li in the different sites of the spinel structure. Nonetheless, these shift differences are enough to allow the concentrations of the different sites to be quantified and monitored following insertion of Li or as a function sample preparation method. ... 

This work consist of a two adding one another experimental parts, discussion and conclusions. In the first experimental part, we report about our investigations of hydrogen intercalation-deintercalation processes in layered InSe and GaSe crystals and powders. In the second one, the influence of intercalated hydrogen on optical properties of these crystals is reported. 

Zhirko Yu.I., Kovalyuk Z.D., Pyrlja M.M., Boledzyuk V.B. (2003) Optical Investigation of Hydrogen Intercalation-Deintercalation Processes in Layered Semiconductor y-InSe Crystals. Proceeding of VIII Int. Confer. Hydrogen Material Science Chemistry of Carbon Nanomaterials 1157. 

This rapid intercalation-deintercalation of ammonia can form the basis for a chemical sensing device. Thomas and Cleary (1996) used Mn2 2S6, a layered material similar to PM2, as the host material for ammonia intercalation and showed a rapid change in the dielectric properties of the host upon exposure to ppm concentrations of ammonia. 

As discussed in the next section, lithiated carbon electrodes are covered with surface films that influence and, in some cases, determine their electrochemical behavior (in terms of stability and reversibility). They are formed during the first intercalation process of the pristine materials, and their formation involves an irreversible consumption of charge that depends on the surface area of the carbons. This irreversible loss of capacity during the first intercalation/deintercalation cycle is common to all carbonaceous materials. However, several hard, disordered carbons exhibit additional irreversibility during the first cycle, in addition to that related to surface reactions with solution species and film formation. This additional irreversibility relates to consumption of lithium at sites of the disordered carbon, from which it cannot be electrochemically removed [346-351],... 

---