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Photoelectrochemical investigations were performed with passivated titanium electrodes. Passive films were formed in 1M H2SO4 at constant potential, UOX , with UOX being varied between 4 and 105V. The results of photocurrent spectra and the potential dependence of the photocurrent suggest a distinction of four different types of film behavior depending on the thickness of the passive film. The most important changes in photoelectrochemical data occur below UOX=30V . An amorphous‐crystalline transition of the passive film can be assumed. This is inferred from the change of the optical transitions with thickness and the potential dependence of the photocurrent which seems to obey the Poole‐Frenkel effect for thinner films. The changes observed with thicker films can be related to an increasing long range order in the passive film. The results demonstrate that photoelectrochemistry is a suitable in situ technique for determining important properties of passive films including structurally related ones.

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The influence of the electrolyte solvents on the cell voltage in lithium-sulfur (Li-S) batteries is investigated. It is found that changing the solvent does not only alter the reaction mechanisms taking place during charge and discharge, but also exerts a pronounced influence on the cell voltage. The changes monitored upon switching from standard ether-based electrolytes to more polar solvents are quite substantial. An increase in the open circuit voltage of up to ∼400 mV could be observed. Both experimental evidence and theoretical calculations are presented in order to elucidate and quantify these effects. It is demonstrated that both the observed trends and the order of magnitude of the measured values can be explained by the free solvation energies of the respective ionic species in the electrolyte systems. Among them, the lithium cation contributes most to the phenomena described. Given that the final reaction products are solid and precipitate from the solution, these effects cannot be exploited to increase the overall energy densities of standard Li-S batteries. However, they are still important both with respect to the fundamental understanding of the electrochemical processes involved as well as practical applications such as liquid, polysulfide-based redox flow batteries.