Lattice model of ionic liquid confined by metal electrodes
Abstract
We study, using Monte Carlo simulations, the density profiles and differential capacitance of ionic liquids confined by metal electrodes. To compute the electrostatic energy, we use the recently developed approach based on periodic Green’s functions. The method also allows us to easily calculate the induced charge on the electrodes permitting an efficient implementation of simulations in a constant electrostatic potential ensemble. To speed up the simulations further, we model the ionic liquid as a lattice Coulomb gas and precalculate the interaction potential between the ions. We show that the lattice model captures the transition between camel-shaped and bell-shaped capacitance curves—the latter characteristic of ionic liquids (strong coupling limit) and the former of electrolytes (weak coupling). We observe the appearance of a second peak in the differential capacitance at ≈0.5 V for 2:1 ionic liquids, as the packing fraction is increased. Finally, we show that ionic size asymmetry decreases substantially the capacitance maximum, when all other parameters are kept fixed.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Feb 22, 2018
- Source ID
- 10.1063/1.5013337
Entities
People
- Alexandre P dos Santos
- Matheus Girotto
- Rodrigo M. Malossi
- Yan Levin
Organizations
- Alexander von Humboldt Foundation
- Coordenação de Aperfeicoamento de Pessoal de Nível Superior
- Federal University of Rio Grande do Sul
- National Council for Scientific and Technological Development
- United States Air Force