Anomalous Underscreening in the Restricted Primitive Model

TL;DR

This paper reports Molecular Dynamics simulations demonstrating anomalous underscreening in dense electrolytes, linked to ion clustering, challenging traditional theories and impacting energy storage technology design.

Contribution

It provides the first simulation evidence of anomalous underscreening in the restricted primitive model, supported by a theoretical ion pairing model.

Findings

Simulation results show anomalous underscreening in concentrated electrolytes.

Ion clustering is connected to the observed underscreening phenomenon.

Theoretical model confirms the simulation trend.

Abstract

Underscreening is a collective term for charge correlations in electrolytes decaying slower than the Debye length. Anomalous underscreening refers to phenomenology that cannot be attributed alone to steric interactions. Experiments with concentrated electrolytes and ionic fluids report anomalous underscreening, which so far has not been observed in simulation. We present Molecular Dynamics simulation results exhibiting anomalous underscreening that can be connected to cluster formation. A theory that accounts for ion pairing confirms the trend. Our results challenge the classic understanding of dense electrolytes impacting the design of technologies for energy storage and conversion.