Transition metal sulfide electrodes

Intercalation electrodes may include either carbon electrodes or transition metal oxide and sulfide electrodes, which intercalate with solution components such as metal cations. The most important example is intercalation of lithium ions with many types of carbonaceous materials at low potentials (0-1.5 V versus Li/Li+)... 

Thin films of oxides and sulfides of transition metals, HS2, LiMn204, LiNi02, LiCo02 with the thickness of 5-15 pm deposited onto supports of A1 or stainless steel were studied as electrodes for PsCs. The electrolyte was the solution of LiAsF in PC. The faradaic process determining pseudocapacitance was the reaction of Li intercalation into the matrix of a transition metal oxide. The capacitance of the studied PsCs was 400 pF/cm for FiNi02 and LiCo02 and 1500 pF/cm for 1182. 

The catalytic asymmetric oxidation of prochiral sulfides by chemical means is a difficult task. While a number of workers have been active in this area during the past few years, few systems simultaneously show good induction of chirality and good catalytic activity. The most common catalysts involve transition-metal complexes (homogeneous or supported) as well as chiral electrodes. These approaches are described successively below. 

Monosnlfides of U, Gd, Th and other metals are obtained from a solution of the normal valent metal sulfide and chloride in an NaCl/KCl eutectic. LaB is prepared by taking La Og and B Og in an LiBO /LiF melt and by using gold electrodes. Crystalline transition metal phosphides are prepared from solutions of oxides with alkali metal phosphates and halides. 

More interesting is the commonly encountered situation where an ion diffuses in a majority electronic conductor. Thus, diffusion in metallic and semiconducting alloys or of inserted species in transition metal oxides and chalcogenides fall into this category. Many electrode reactions are of this type. Lithium diffusion in j5-LiAl and other alloys is of interest in negative electrode reactions for advanced hthium batteries hydrogen and lithium diffusion in oxides (e.g. VeOn) and sulfides (e.g. TiSa) are of importance as positive electrode reactions for batteries and elec-trochromic devices. 

Liquid Organic Electrolyte Batteries. These cells use lithium metal for the negative electrode, a liquid organic aprotic solution for the electrolyte, and transition metal compounds (oxides, sulfides, and selenides) for the positive electrode. These transition metal compounds are insertion or intercalation compounds and possess a structure into which lithium ions can be inserted or from which they can be removed during discharge and charge, respectively. 

Table 10.1 summarizes the characteristics of common ISEs and a number of new sensors in this field. We have not included in this table the liquid or polymer membrane-based electrodes which are selective, but rather fragile (for more details on such membranes see References 58,59). ISEs of the first kind are not very numerous, e.g., F -ISE (monocrystalhne membrane based on LaFj), Ag" -ISE (silver salts), or Na" -ISE (Na alumino-silicate glass or polyciystalline NASICON [Na super ionic conductor] membranes). Most of the ISEs are of the second kind and are based on insoluble silver salts for example, halide ISEs (CE, Br, I"), Cd ", Pb ", Cu ", etc. Such ISEs use mixtures of insoluble salts based on silver sulfide or silver selenide. Recently, Vlasov etal. and Neshkova have proposed several glasses sensitive to transition metals. Typical ISE devices are shown in Figure 10.5. Thin-layer chemical sensors based on chalcogenide glasses have also been developed. ... 

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