Substituted ferrocenes and iodine as synergistic thermoelectrochemical heat harvesting redox couples in ionic liquids

Abstract

Combining ferrocene and iodine results in enhanced thermoelectrochemical (or thermogalvanic) waste heat harvesting abilities, for both the Seebeck coefficient and the overall power output. All systems displayed a mixture of ferrocene, ferrocenium, iodine and triiodide. The observed enhancement correlates with lower electron-density on the ferrocene; the synergistic improvement observed for mixtures of substituted ferrocenes and iodine is attributed to the formation of charge-transfer complexes. Combining dibutanoylferrocene and iodine resulted in the highest Seebeck coefficient of 1.67 mV K(-1).

Thermoelectrochemistry using conventional and novel gelled electrolytes in heat-to-current thermocells

“…Platinum-coated CR2032 casings were supplied by MTI Corporation. Thermoelectrochemical measurements were made using an in-house constructed temperature-control apparatus which has been described in detail elsewhere; [14,19] a schematic of the overall layout is displayed in Figure S1 in the Supplementary Data. All cells were measured in a thermally 'parallel' arrangement, as shown in Figure S1.…”

“…-1.5 mV K -1 , [40] and is consistent with thermoelectrochemical potentials measured in CR2032 casings being lower than those measured by more impractical but precisely thermostated assemblies. [11,19,35,52] The reason for this is discussed in detail in the modelling section. Similar power curves were also obtained for thermocells containing the poly(sodium acrylate) and agar agar gelled electrolytes ( Figures S7 and S9, respectively); both displayed the expected parabola power curve.…”

“…explicitly coordinating non-aqueous media, [14] high spin low spin transitions, [17] electrode side reactions, [11] electrode intercalation processes [18] and solution-phase synergistic interactions. [19] Liquid electrolytes are effective for thermoelectrochemical systems (or 'thermocells'), insomuch as they can possess high Seebeck coefficients for certain redox couples, typically possess high solubility for these redox couples, result in a high ionic conductivity of these redox couples, and are flexible. [14] However, they can also leak and suffer from parasitic heat transport, frustrating the formation of sharp and stable temperature gradients.…”

Chiral and Redox‐Active Room‐Temperature Ionic Liquids Based on Ferrocene and l‐Proline

“…However, interactions between iodine and ferrocene species leading to modified electrochemical properties have been reported , . In this work, shifts of the redox potentials owing to interactions between the iodine atom and the ferrocenyl units, as observed in CV experiments of substituted ferrocenium triiodides in ILs, were not observed; the Fc/Fc + formal potentials of the iodides 2 – 6 are the same as those of the NTf 2 – salts 7 – 11 (Table ).…”

Electrical power production from low-grade waste heat using a thermally regenerative ethylenediamine battery

“…Different types of thermoelectrochemical systems (TESs) are being investigated to convert low-grade waste heat to electrical power [9][10][11][12]. Most of the reported TESs rely on using a chemical that has temperature-dependent reduction and/or oxidation potentials in aqueous solutions, but the performance of these TESs needs to be improved in terms of electrical power densities and thermalelectric conversion efficiencies [11,13]. For example, a maximum power density of 1.5 Wm -2 -electrode area with a Carnot efficiency of 1.4% was achieved in a TES operated with a ferrocyanide/ferricyanide redox solution and carbon nanotube electrodes when operated with a temperature difference of 60 °C [14].…”