Water, not salt, causes most of the Seebeck effect of nonisothermal aqueous electrolytes

Ole Nickel; Ludwig J. V. Ahrens-Iwers; Robert H. Meißner; Mathijs Janssen

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arXiv · 2309.07853

Water, not salt, causes most of the Seebeck effect of nonisothermal aqueous electrolytes

Ole Nickel·Ludwig J. V. Ahrens-Iwers·Robert H. Meißner·Mathijs Janssen

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Abstract

When two electrolyte-immersed electrodes have different temperatures, a voltage $\Delta \psi$ can be measured between them. This electrolyte Seebeck effect is usually explained by cations and anions flowing differently in thermal gradients. However, our molecular dynamics simulations of aqueous electrolytes reveal a large temperature-dependent potential drop $\chi$ near blocking electrodes caused by water layering and orientation. The difference in surface potentials at hot and cold electrodes is more important to the Seebeck effect than ionic thermodiffusion, $\Delta \psi \sim \chi_{\rm hot}-\chi_{\rm cold}$.

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Ole Nickel, Ludwig J. V. Ahrens-Iwers, Robert H. Meißner, Mathijs Janssen. 2023-09-14. Water, not salt, causes most of the Seebeck effect of nonisothermal aqueous electrolytes. https://arxiv.org/abs/2309.07853

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