Properties of Interphases

The thickness of the interphase is proportional to the amount of electrolytes consumed during its formation cycles the irreversible capacity in the initial cycles was often used to quantify the thickness as a measure for the quahty of the SEI. Based on the correlation between the thickness of interphase and irreversible capacity, Dahn et al. developed a high-precision coulometry method to study the growth of interphase formed on graphite surface [70]. Their experimental results showed that time and temperature, while not cycle count, are the dominant contributors to the growth of the SEI. They also addressed the equations (5.1-5.3) to describe the SEI growth rate and consumption of Li on graphite electrode  

Herein, x represents the thickness of the passivating layer. A is a proportional constant, and t is time. Therefore, the SEI thickness increases approximately with tirne consistent with a process where the temperature-dependent SEI growth is inversely proportional to the SEI thickness. 

Not long after Dahn s work, Shenoy et al. employed molecular dynamics simulations to study the formation and growth of solid electrolyte interphase for the case of EC, DMC, and mixtures of these two solvent on lithium metalhc electrode [61]. In their work, they investigated the constitutes and structures of SEI on lithium metal electrode with the dependence of electrolyte composition and temperature change. The results show that the SEI films grow faster in the case of EC compared to DMC, with EC+DMC mixtures falling in between, as shown in Fig. 5.22. 

The density of Li consumed in the SEI tends to be of asymptotic limit, which depends on the electrolyte composition but weakly on the temperature. In addition, the Li density in SEI formed in EC-based electrolyte is slightly higher than that in DMC and EC-i-DMC mixtures, suggesting that EC is more reactive compared to 

Compared to the studies on the chemistry composition, structure, and formation mechanisms of SEI, not too much attention has been paid to understanding the ion transport mechanism by which Li passes through the SEI during the charging and 

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In this Section we use Eqs. (2)-(10) to derive several relations for the free energy F ci of a stationary noiiuniform alloy. These relations can be used to study properties of interphase and antiphase boundaries, nucleation problems, etc. 

The most fundamental equation governing the properties of interphases is the Gibbs adsorption isotherm ... 

This work investigates the behaviour of elastomeric chains (polybutadienes of identical molecular weight but different microstructures) in the close vicinity of carbon black surfaces in order to attain a better understanding of the structure and properties of interphases. Elastomer-filler interactions are assessed through the study of the thermal properties and NMR relaxation characteristics of the corresponding materials. MAS solid-state NMR provides information on the effect exerted by polymer-filler interactions on the mobility of the various constitutive species of the macromolecular backbone. 

Properties of interphases relevant for an understanding of structures and dynamics therein can be grouped into atomic (microscopic) and macroscopic ones. Nevertheless the close relationships between both types of properties have allowed us to infer conclusions with respect to atomic models from macroscopic information. Investigations of these properties have gained tremendously in recent years from the application of a broad variety of spectroscopic methods. Certainly many properties, in particular macroscopic ones, can be studied by measuring surface properties (like conductivity, hardness, etc.) with non-spectroscopic methods. In most cases the results will be rather general and a complete understanding of relationships between... 

Measurements at equilibrium can be divided into three separate categories, potentiometric measurements, measurements of the properties of interphases and impedance measurements. The first group will not be discussed here since the various theoretical and experimental aspects of potentiometry are very well covered by texts on solution electro-chemistry and on analytical chemistry. 

The interphase is the volume of material ia which the properties of one substance gradually change iato the properties of another. The iaterphase is useful for describiag the properties of an adhesive bond. The interface contained within the iaterphase, is the plane of contact between the surface of one material and the surface of another. Except ia certain special cases, the iaterface is imaginary. It is useful ia describiag surface eaergetics. 

Rate equations are used to describe interphase mass transfer in batch systems, packed beds, and other contacting devices for sorptive processes and are formulated in terms of fundamental transport properties of adsorbent and adsorbate. 

As we have already seen, when an alloy contains more of the alloying element than the host metal can dissolve, it will split up into two phases. The two phases are "stuck" together by interphase boundaries which, again, have special properties of their own. We look first at two phases which have different chemical compositions but the same crystal structure (Fig. 2.5a). Provided they are oriented in the right way, the crystals can be made to match up at the boundary. Then, although there is a sharp change in... 

Lipatov et al. [116,124-127] who simulated the polymeric composite behavior with a view to estimate the effect of the interphase characteristics on composite properties preferred to break the problem up into two parts. First they considered a polymer-polymer composition. The viscoelastic properties of different polymers are different. One of the polymers was represented by a cube with side a, the second polymer (the binder) coated the cube as a homogeneous film of thickness d. The concentration of d-thick layers is proportional to the specific surface area of cubes with side a, that is, the thickness d remains constant while the length of the side may vary. The calculation is based on the Takayanagi model [128]. From geometric considerations the parameters of the Takayanagi model are related with the cube side and film thickness by the formulas ... 

The electrical double layer has also been investigated at the interface between two immiscible electrolyte solutions and at the solid electrolyte-electrolyte solution interface. Under certain conditions, the interface between two immiscible electrolyte solutions (ITIES) has the properties of an ideally polarized interphase. The dissolved electrolyte must have the following properties ... 

Lindner et al. carried out detailed studies on the use of the sol-gel procedure to obtain new materials as suitable matrices [45]. A co-condensation of Si(OR)4, Si(OR)3-spacer-Si(OR)3 and Si(OR)3-spacer-ligand resulted in new hybrid materials, the properties of which strongly depended upon the spacer and the ratio of the different components used. Most of these materials were characterised with IR, EXAFS, and EDX spectroscopy, scanning electron microscopy and solid state NMR spectroscopy. Solid state 31P NMR was used to quantify the mobility of the interphases the changes in line-... 

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