TY - JOUR A1 - Janssen, Mathijs A1 - Bier, Markus T1 - Transient response of an electrolyte to a thermal quench T2 - Physical Review E N2 - We study the transient response of an electrolytic cell subject to a small, suddenly applied temperature increase at one of its two bounding electrode surfaces. An inhomogeneous temperature profile then develops, causing, via the Soret effect, ionic rearrangements towards a state of polarized ionic charge density q and local salt density c. For the case of equal cationic and anionic diffusivities, we derive analytical approximations to q,c, and the thermovoltage VT for early (t≪τT) and late (t≫τT) times as compared to the relaxation time τT of the temperature. We challenge the conventional wisdom that the typically large Lewis number, the ratio a/D of thermal to ionic diffusivities, of most liquids implies a quickly reached steady-state temperature profile onto which ions relax slowly. Though true for the evolution of c, it turns out that q (and VT) can respond much faster. Particularly when the cell is much bigger than the Debye length, a significant portion of the transient response of the cell falls in the t≪τT regime, for which our approximated q (corroborated by numerics) exhibits a density wave that has not been discussed before in this context. For electrolytes with unequal ionic diffusivities, VT exhibits a two-step relaxation process, in agreement with experimental data of Bonetti et al. [J. Chem. Phys. 142, 244708 (2015)]. KW - Electrochemistry, Electrokinetic flows, Ionic transport, Nonequilibrium & irreversible thermodynamics, Thermoelectrics, Thermophoresis, Ionic fluids, Condensed Matter, Materials & Applied Physics, Statistical Physics, General Physics Y1 - 2019 UR - https://opus4.kobv.de/opus4-fhws/frontdoor/index/index/docId/2477 UR - https://doi.org/10.1103/PhysRevE.99.042136 VL - 99 IS - 4 SP - 042136 ER -