Relatively high-Seebeck thermoelectric cells containing ionic liquids supplemented by cobalt redox couple

Meanwhile no general and reliable equation determining the Seebeck coefficient (S-e) and involving electrochemical reaction effects was derived for solutions. We reported the database of 15,000 ionic liquids supplemented by three different redox couple systems: 0.01 mol/lCo(3+/2+) (bpy)(3), 0.01 mol/I-3(-)/3I(-) and 0.2 mol/lI(3)(-)/3I(-), and the corresponding estimated Seebeck coefficients. We also reported methods for estimating Seebeck coefficients for those systems. First, Seebeck coefficients were measured for 17 ionic liquids and the 3 redox couples independently, and afterwards an analytical QSPR equation was derived after which the Seebeck coefficients for all possible combinations of cations and anions ( resulting in 15,000 conceivable ionic liquid compounds) were derived. Following this, we analyzed the data and discovered tendencies and regularities. It was revealed that small, symmetrical and not branched cations and anions which contained less electronegative atoms, made the Seebeck increased. The highest S-e = 2.3 mV/K, was observed for small ammonium and phosphonium cations with a triethyl-n-hexylboride anion. We also discovered that for thermo-electric applications cobalt-based redox couples are much better than the ones based on the iodine/iodide system. (C) 2020 Elsevier B.V. All rights reserved.