The influence of counterion structure identity on conductivity, dynamical correlations, and ion transport mechanisms in polymerized ionic liquids

We used equilibrium and non-equilibrium atomistic simulations to probe the influence of anion chemistry on the true conductivity, dynamical correlations, and ion transport mechanisms in polymeric ionic liquids. An inverse correlation was found between anion self-diffusivities, ionic mobilities, and the anion size for spherical anions. While some larger asymmetric anions had higher diffusivities than smaller spherical anions, their diffusivities and mobilities did not exhibit a direct correlation to the anion volumes. The conductivity and anion dynamical correlations also followed the same trends as displayed by the diffusivity and mobility of anions. All the systems we examined displayed positively correlated motion among anions, suggesting a contribution that enhances the conductivity beyond the ideal Nernst-Einstein value. Analysis of ion transport mechanisms demonstrated very similar hopping characteristics among the spherical anions despite differences in their sizes.

Automated summary

In this study, equilibrium and non-equilibrium atomistic simulations were used to investigate the influence of anion chemistry on conductivity, dynamical correlations, and ion transport mechanisms in polymeric ionic liquids. The results showed an inverse correlation between anion self-diffusivities, ionic mobilities, and anion size for spherical anions. While some larger asymmetric anions had higher diffusivities than smaller spherical anions, their diffusivities and mobilities did not exhibit a direct correlation with anion volumes. The conductivity and anion dynamical correlations also followed the same trends as the diffusivity and mobility of anions. All the systems examined displayed positively correlated motion among anions, indicating a contribution that enhances conductivity beyond the ideal Nernst-Einstein value. Analysis of ion transport mechanisms demonstrated very similar hopping characteristics among spherical anions despite differences in their sizes.