Insertion electrochemistry

Kavan, L. Rathousky, J. Gratzel, M. Shklover, V. Zukal, A. 2000. Surfactant-templated Ti02 (anatase) Characteristic features of lithium insertion electrochemistry in organized nanostructures. J. Phys. Chem. B 104 12012-12020. 

The insertion electrochemistry of PCMs Most of the PCMs possess two characteristic properties, they have redox-active metal centers and they have an open... 

These reactions are solid-state insertion electrochemical processes with coupled electron and ion transfers. Figure 4 includes the standard potential of hex-acyanoferrate in aqueous solution. It is rather surprising that the data for the solid-state insertion electrochemistry and... 

Octacyanomolybdates and octacyano-tungstates exhibit an insertion electrochemistry, which is rather similar to that of the hexacyanoferrates, [67] and the compounds show a pronounced elec-trochromic effect [68]. 

Tetracyanoquinodimethane (TCNQ) and many of its derivatives are easily reduced to anions of the type TCNQ-, which form salts with various cations. With many cations, e.g., tetrathiafulvalene cations (TTF+), and N-methyl phenazinium cations (NMP+), the TCNQ- anions form electronically conducting salts (- molecular metals, -> charge-transfer complexes) that can be used as electrodes, especially because of their electrocatalytic properties (- biosensors, -> electrocatalysis, -> molecular metals) [i,ii]. TCNQ undergoes insertion electrochemical reactions (-> insertion electrochemistry) leading to TCNQ salts [iii, iv]. Polymers... 

Insertion electrochemistry — A branch of solid-state electrochemistry dealing with the electrochemical behavior of insertion electrodes. 

From a fundamental point of view, insertion electrochemistry deals with the thermodynamics and kinetics of intercalation processes starting at the electrodesolution and current collector-electrode interfaces, and occurring (propagating) into the electrodes interior. Very often (but not mandatory) intercalation processes into host electrodes occur in the form of first-order phase transition, and thus the classical galvanostatic charging of the electrode can be beneficially combined with simultaneous in situ XRD characterization. The latter allows the distinction between solid-solution and the two-phase coexistence paths of the intercalation process. 

Insertion electrochemistry differs from the conventional electrochemistry of solution redox-species in the following respects ... 

Solid-state electrochemistry — is traditionally seen as that branch of electrochemistry which concerns (a) the -> charge transport processes in -> solid electrolytes, and (b) the electrode processes in - insertion electrodes (see also -> insertion electrochemistry). More recently, also any other electrochemical reactions of solid compounds and materials are considered as part of solid state electrochemistry. Solid-state electrochemical systems are of great importance in many fields of science and technology including -> batteries, - fuel cells, - electrocatalysis, -> photoelectrochemistry, - sensors, and - corrosion. There are many different experimental approaches and types of applicable compounds. In general, solid-state electrochemical studies can be performed on thin solid films (- surface-modified electrodes), microparticles (-> voltammetry of immobilized microparticles), and even with millimeter-size bulk materials immobilized on electrode surfaces or investigated with use of ultramicroelectrodes. The actual measurements can be performed with liquid or solid electrolytes. 

A novel mesoporous molecular sieve was prepared whose framework is composed of anatase nanocrystals stabilized by aluminum. The material was characterized by X-ray diffraction, Raman spectroscopy, nitrogen adsorption and lithium insertion electrochemistry. The faradaic capacity and charge-transfer kinetics is considerably higher that those of analogous structures stabilized by Zr. 

It is interesting that the transfer of ions from one phase to another can also result from the creation of a potential difference by electron transfer. Imagine that a solid phase contains immobile electroactive ions like Fe ". These ions can be reduced however, this would violate the charge balance, unless other cations can diffuse into the solid, or anions could leave the solid. This is a very frequently encountered case in solid-state electrochemistry (see Chap. II.8). One can understand this insertion electrochemistry as resulting from the creation of an electric field due to the electron transfer. The same phenomena can also be observed when droplets of an immiscible liquid contain electroactive species, and these droplets are deposited onto an electrode surface, which is introduced into an aqueous solution [8]. 

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