Ionic conductivity

Quantum mechanics

Chemical physics

Materials science

Density functional theory

Debye

Debye–Hückel equation

Statistical physics

Percolation theory

Debye length

Thermodynamics

Physics

Coulomb

Condensed matter physics

Conductivity

Ionic bonding

Electrode

Electron

Electrolyte

Physical Review Letters

The conductivity of ionic solutions is arguably their most important trait, being widely used in electrochemical, biochemical, and environmental applications. The Debye-Hückel-Onsager theory successfully predicts the conductivity at very low ionic concentrations of up to a few millimolars, but there is no well-established theory applicable at higher concentrations. We study the conductivity of ionic solutions using a stochastic density functional theory, paired with a modified Coulomb interaction that accounts for the hard-core repulsion between the ions. The modified potential suppresses unphysical, short-range electrostatic interactions, which are present in the Debye-Hückel-Onsager theory. Our results for the conductivity show very good agreement with experimental data up to 3 molars, without any fit parameters. We provide a compact expression for the conductivity, accompanied by a simple analytical approximation.

Conductivity of Concentrated Electrolytes