Past colloquia and seminars


Underscreening, Overscreening, and Blue Energy - how fundamental electrostatics can be utilized in a thermodynamic engine for sustainable energy conversion

General public Colloquium / Congress / Forum

These days the storage of energy and the reuse of waste heat is more important than all times.
Supercapacitive energy storage not only allows to store electric energy, but its physical functionality also allows to exploit the charging process itself in novel thermodynamic cycles. I will present such cycles to harvest Blue Energy from salinity steps and from waste heat. For this purpose, we will study the physics of so-called electric double layers (EDLs), those regions next to electrodes of a capacitor where the mobile charges in the electrolyte arrange themselve to screen the electrode's electrostatic field.
At sufficiently low ion concentration, EDLs are well described by Poisson-Boltzmann theories for point-like ions. At higher concentrations, however, ionic sizes matter and steric effects determine the screening of charges, leading to overscreening and underscreening. The latter currently is discussed controvelsially and I will present an explanation for regular and anomalous underscreening that question our understanding of dense electrolytes.

When? 09.11.2022 16:50
Where? PER 08 0.51
Chemin du Musée 3
1700 Fribourg
speaker Dr. Andreas Härtel
Institute of Physics, University of Freiburg (DE)
Contact Département de physique, groupe Brader
Prof. Joseph Brader