Interfacial layering in the electric double layer of ionic liquids

Abstract

Ions in ionic liquids and concentrated electrolytes reside in a crowded, strongly-interacting environment, leading to the formation of discrete layers of charges at interfaces. Here, we propose a continuum theory that captures the transition from overscreening-- alternating layers of excess charge at low surface potential, to overcrowding-- the formation of dense layers of charge of the same sign at high surface potential. The model outputs slowly-decaying oscillations in the charge density with a wavelength of single ion diameters, as shown by analysis of the gradient expansion. The gradient expansion suggests a new structure for partial differential equations describing the electrostatic potential at charged interfaces. We find quantitative agreement between the theory and molecular simulations in the differential capacitance and concentration profiles.

References in corpus (4)

• The Electrostatic Screening Length in Concentrated Electrolytes Increases with Concentration
• Underscreening in concentrated electrolytes
• Charge Oscillations in Ionic Liquids: A Microscopic Cluster Model
• "Kohn-Shamification" of the classical density-functional theory of inhomogeneous polar molecular liquids with application to liquid hydrogen chloride

Cited by in corpus (2)

• Electric field based Poisson-Boltzmann: Treating mobile charge as polarization
• On the equivalence of self-consistent equations for nonuniform liquids: a unified description of the various modifications