A minimal electrostatic theory for the Seebeck coefficient in liquids

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.