Capacitive density functional theory for structure and screening in ionic fluids and electric double layers with applications in sustainability
Final Report Abstract
The funded project capDFT focused on the theoretical description of electrolytes, in particular in contact with charged surfaces like electrodes. At such interfaces ions form so-called electric double layers (EDLs) that are key in supercapacitors, which can store electric energy but can also be utilized to transform heat into electric energy or to harvest energy from mixing processes. In the project, we developed a new theoretical approach to efficiently describe the distribution of ions in EDLs in the framework of classical density functional theory (DFT). The approach is capable of taking into account the important correlations between steric and electrostatic particle interactions in electrolyte systems. We used the approach to explain effects as structural underscreening and to study inplane structure parallel to the electrode in EDLs. We further developed models for the electrode-electrolyte interaction that respect the presence of solvent particles. This interaction mainly determines the capacitance of EDLs and its heat production during (dis)charging processes. For verification of our results and further studies, we performed additional molecular dynamics simulations. In this way, we found long-ranged underscreening for the first time from theoretical calculations and could explain its origin by the formation of neutral cluster in electrolytes. The developed codes from our project are publicly available in the capDFT library on github.
Publications
-
Bayesian unsupervised learning reveals hidden structure in concentrated electrolytes. The Journal of Chemical Physics, 154(13).
Jones, Penelope; Coupette, Fabian; Härtel, Andreas & Lee, Alpha A.
-
Capdft, a c++ library to perform calculations in the framework of classical density functional theory, 2021
A. Härtel & M. Bültmann
-
Primitive model electrolytes in the near and far field: Decay lengths from DFT and simulations. The Journal of Chemical Physics, 154(12).
Cats, P.; Evans, R.; Härtel, A. & van, Roij R.
-
Reversible heat production during electric double layer buildup depends sensitively on the electrolyte and its reservoir. The Journal of Chemical Physics, 154(6).
Glatzel, Fabian; Janssen, Mathijs & Härtel, Andreas
-
Extension of the primitive model by hydration shells and its impact on the reversible heat production during the buildup of the electric double layer. The Journal of Chemical Physics, 156(3).
Pelagejcev, Philipp; Glatzel, Fabian & Härtel, Andreas
-
The primitive model in classical density functional theory: beyond the standard mean-field approximation. Journal of Physics: Condensed Matter, 34(23), 235101.
Bültmann, Moritz & Härtel, Andreas
-
„A density-functional-theory study on the structure of electrolytes“, PhD thesis (University of Freiburg, 2022)
M. Bültmann
-
Anomalous Underscreening in the Restricted Primitive Model. Physical Review Letters, 130(10).
Härtel, Andreas; Bültmann, Moritz & Coupette, Fabian
-
In-plane structure of the electric double layer in the primitive model using classical density functional theory. The Journal of Chemical Physics, 159(18).
Cats, Peter & Härtel, Andreas
-
„Electrostatic screening in electric double layers“, Habilitation treatise (University of Freiburg, 2023).
A. Härtel
