Solid decomposition voltage

In practice, for a ternary system, the decomposition voltage of the solid electrolyte may be readily measured with the help of a galvanic cell which makes use of the solid electrolyte under investigation and the adjacent equilibrium phase in the phase diagram as an electrode. A convenient technique is the formation of these phases electrochemically by decomposition of the electrolyte. The sample is polarized between a reversible electrode and an inert electrode such as Pt or Mo in the case of a lithium ion conductor, in the same direction as in polarization experiments. The... 

Before Nernst had put forward his theory, Bodlander (Zeitschr. physik. Chcm., 27, 55, 1898) had been able to calculate the solubility of a salt by the measurement of its decomposition voltage, and had found that where the reaction occurring is the dissociation of a solid salt into solid uncharged atoms, the work done to split up the salt into its ions, and discharge these at the electrodes, is very nearly equal to the heat of formation. 

LijN has a low decomposition potential, 0.445 V, which limits its usefulness as a practical solid electrolyte in batteries. Various Li3N-derivative phases have been synthesised, such as cubic Li5Nl2 with an antifluorite-derivative structure and a related phase in the system, LijN-Lil-LiOH. Some of these have high conductivity and the latter materials in particular are comparable to those of H-doped LijN. They also have a much higher decomposition voltage, 1.5V, but do suffer from increased sensitivity to chemical attack. 

Plates of inert metals such as platinum and graphite serve in solid state electrochemical cells to supply electrons to the sample, but block the passage of material and ions for voltages below the thermodynamic decomposition voltage of the SE. The ionic current is blocked since the metals do not contain the required material that can provide the ions. In addition, the metal blocks are applied in a way that blocks the exchange of material with, e.g., the surrounding atmosphere, as well. Not only inert metals can serve for that purpose, but also any electron conductor, whether metal or semiconductor, that stays chemically intact and is impermeable to the material flow either in the form of ions or neutral species. 

The magnitude of the errors in determining the flat-band potential by capacitance-voltage techniques can be sizable because (a) trace amounts of corrosion products may be adsorbed on the surface, (b) ideal polarizability may not be achieved with regard to electrolyte decomposition processes, (c) surface states arising from chemical interactions between the electrolyte and semiconductor can distort the C-V data, and (d) crystalline inhomogeneity, defects, or bulk substrate effects may be manifested at the solid electrode causing frequency dispersion effects. In the next section, it will be shown that the equivalent parallel conductance technique enables more discriminatory and precise analyses of the interphasial electrical properties. 

Electrical trees consist of visible permanent hollow channels, resulting from decomposition of the material, and show up clearly in polyethylene and other translucent solid dielectrics when examined with an optical microscope. Fresh, unstained water trees appear diffuse and temporary. Water trees consist of very fine paths along which moisture has penetrated under the action of a voltage gradient. Considerable force is required to effect this... 

Division of the overall process into two stages production of electricity and water electrolysis proper. Let us replace a single photoelectrochemical cell by the combination of a solar cell (solid state or liquid junction ) and an ordinary electrolyzer. In this case, production of electricity and electrolytic decomposition of water, which are combined in a photoelectrolysis cell, appear to be distributed between two specially designed devices. This enables the necessary voltage to be attained by connecting in series several... 

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