A minimal electrostatic theory for the Seebeck coefficient in liquids

Abstract

The Seebeck coefficient in liquids often reaches the mV/K range, yet its microscopic origin remains unclear due to the complexity of electrolyte systems. Here we propose a minimal electrostatic theory focusing on solvation entropy. Using the extended Born equation with temperature ($T$)-dependent dielectric constant ($\varepsilon$), we quantitatively reproduce the experimentally observed magnitude. The theory clarifies that large valence, small cationic radius, small dielectric constant, and large $\frac{d\varepsilon}{dT}$ are key factors for enhanced liquid Seebeck response.

Figures (1)

• Figure 1: (a) Schematic figure of core-shell structure in dielectric medium. Radius of the core and the shell are $a$ and $b$ m, respectively. Relative dielectric constant ($\varepsilon_{{\rm r}i} (i=0,1,2)$) of the core, the shell, and the medium is $\varepsilon_{{\rm r}0}$, $\varepsilon_{{\rm r}1}$, and $\varepsilon_{{\rm r}2}$, respectively. The core represents a cation with a point charge $q$ at original point O. The shell and the medium represent a solvation structure and solvent, respectively. (b) Schematic figure of cation gas. A point charge $q$ at O is embedded in a medium with $\varepsilon_{{\rm r}0}$. This situation represents that a core is not in the solvent but is isolated.