Can charged colloidal particles increase the thermoelectric energy conversion efficiency?

Abstract

a Currently, liquid thermocells are receiving increasing attention as an inexpensive alternative to conventional solid-state thermoelectrics for low-grade waste heat recovery applications. Here we present a novel path to increase the Seebeck coefficient of liquid thermoelectric materials using charged colloidal suspensions; namely, ionically stabilized magnetic nanoparticles (ferrofluids) dispersed in aqueous potassium ferro-/ferricyanide electrolytes. The dependency of thermoelectric potential on experimental parameters such as nanoparticle concentration and types of solute ions (lithium citrate and tetrabutylammonium citrate) is examined to reveal the relative contributions from the thermogalvanic potential of redox couples and the entropy of transfer of nanoparticles and ions. The results show that under specific ionic conditions, the inclusion of magnetic nanoparticles can lead to an enhancement of the ferrofluid's initial Seebeck coefficient by 15% (at a nanoparticle volume fraction of B1%). Based on these observations, some practical directions are given on which ionic and colloidal parameters to adjust for improving the Seebeck coefficients of liquid thermoelectric materials.

Colloidal dispersions of oxide nanoparticles in ionic liquids: elucidating the key parameters

“…6 The addition of charged nanoparticles, for example, can improve the thermoelectric properties compared to the use of a solvent alone. 7,8 Increasing the electrical conductivity of colloidal dispersions provides new possibilities, for example, complex electrolytes for electrochemical devices. 6 In the past, several approaches were used to stabilise nanoparticles in ionic liquids.…”

Inversion of thermodiffusive properties of ionic colloidal dispersions in water-DMSO mixtures probed by forced Rayleigh scattering

“…When submitted to a gradient of temperature rT , ionic nanoparticles (NPs) dispersed in a polar solvent are subjected both to the Ludwig-Soret e↵ect [1], which induces a gradient of volume fraction r and a Seebeck e↵ect [2,3], which induces an electric field E. This can be used for potential thermoelectric applications in terms of heat recovery [4][5][6][7][8][9][10]. In stationary conditions, both r and E are proportional to rT and the NPs migrate either towards the cold region or towards the hot region depending on the sign of their Soret coe cient S T , given (at high dilution) by r = S T rT .…”

Термоэлектрические И Термоэлектрокинетические Явления В Жидких Биологических Системах-=sup=-*-=/Sup=-

“…Помимо работ [9,10] можно отметить [14,15]. Интерес к термоэлектрическим свойствам коллоидных систем обусловлен прежде всего перспективами их применения в термоэлектрохимических генераторах [16].…”