Evaluation of electrochemical methods for determination of the seebeck coefficient of redox electrolytes

Recent advances in thermoelectrochemical cells, which are being developed for harvesting low grade waste heat, have shown the promise of cobalt bipyridyl salts as the active redox couple. The Seebeck coefficient, Se, of a redox couple determines the open circuit voltage achievable, for a given temperature gradient, across the thermoelectrochemical cell. Thus, the accurate determination of this thermodynamic parameter is key to the development and study of new redox electrolytes. Further, techniques for accurate determination of Se using only one half of the redox couple reduces the synthetic requirements. Here, we compare three different experimental techniques for measuring Se of a cobalt tris(bipyridyl) redox couple in ionic liquid electrolytes. The use of temperature dependent cyclic voltammetry (CV) in isothermal and non-isothermal cells was investigated in depth, and the Se values compared to those from thermo-electromotive force measurements. Within experimental error, the Se values derived from CV methods were found to be in accordance with those obtained from electromotive force (emf) measurements. The applicability of cyclic voltammetry techniques for determining Se when employing only one part of the redox couple was demonstrated

The zwitterion 1-butylimidazolium-3- (n-butanesulfonate)

The mol&shy;ecule of the title compound, C11H20N2O3S, contains a positively charged imidazolium head group and a negatively charged sulfonate tethered together by a four-carbon chain. There is weak intermolecular hydrogen bonding within the structure between the sulfonate O atoms and the H atoms of the imidazolium ring. The sulfonate group causes a twisting of the butyl chain and a decrease in the dihedral angle between the second and third carbon chain compared to the unsubstituted butyl group.<br /

Ionic liquids and reactions at the electrochemical interface

Ionic liquids (ILs) represent a fascinating, and yet to be fully understood, medium for a variety of chemical, physical and biological processes. Electrochemical processes form an important subset of these that are particularly of interest, since ILs tend to be good electrochemical solvents and exhibit other properties which make them very useful as electrolytes in electrochemical devices. It is important therefore to understand the extent to which electrochemical reactions and processes behave in a relatively &ldquo;normal&rdquo;, for example aqueous solution, fashion as opposed to exhibiting phenomena more uniquely the product of their organic ionic nature. This perspective examines a range of electrochemical reactions in ionic liquids, in many cases in the context of real world applications, to highlight the phenomena as far as they are understood and where data gaps exist. The important areas of lithium and conducting polymer electrochemistry are discussed in detail.<br /

Organic ionic plastic crystals : recent advances

Investigations into the synthesis and utilisation of organic ionic plastic crystals have made significant progress in recent years, driven by a continued need for high conductivity solid state electrolytes for a range of electrochemical devices. There are a number of different aspects to research in this area; fundamental studies, utilising a wide range of analytical techniques, of both pure and doped plastic crystals, and the development of plastic crystal-based materials as electrolytes in, for example, lithium ion batteries. Progress in these areas is highlighted and the development of new organic ionic plastic crystals, including a new class of proton conductors, is discussed.<br /