On the effect of surface functional groups on the structural and dynamical properties of an ionic liquid confined in zeolite templated carbons studied through molecular simulations

TL;DR

This study uses molecular dynamics simulations to explore how surface functional groups on zeolite templated carbons influence the structural and dynamical behavior of confined ionic liquids, revealing limited structural impact but notable effects on ion diffusion.

Contribution

It provides new insights into how different surface chemistries affect electrolyte ion behavior under confinement, which is crucial for energy storage applications.

Findings

Functional groups have limited impact on electrolyte structure.

Surface chemistry influences ion diffusion coefficients.

Effect varies with ion type and property.

Abstract

Porous carbons are used in a wide range of applications, including electrochemical double layer capacitors for energy storage, in which electrolyte ion properties under confinement are crucial for the performance of the systems. While many synthesis techniques lead to the presence of surface functional groups, their effect on the adsorption and diffusion of electrolyte ions is still poorly understood. In this study we investigate the effect of surface chemistry on dynamical and structural properties of adsorbed ions through molecular dynamics simulations of a neat ionic liquid in contact with several zeolite templated carbons. The steric and specific influence of functional groups is explored using three structures: a structure without any functional groups; a structure with ester, hydroxyl, anhydride acid and carboxyl functional groups; and a structure where the oxygen and hydrogen atoms are replaced by carbon atoms. We show that the functionalization has a limited impact on the structure of the confined electrolyte but affects the diffusion coefficients, and that the relative importance of the structure and chemical nature of the functional groups is not the same depending on the ion type and property considered.