Fig. 3: Molecular design of anionic moiety for enhanced Li⁺ migration.

a Chemical structure (top) and MESP (bottom) of the ZMs with different anions (SO₃^– and TFSI^–). The blue and red represent the electron-rich and electron-deficient regions, respectively. b Ion-ion interaction energies between the ZMs with different anions (SO₃^– and TFSI^–) and Li⁺. c Snapshots showing the configuration and distance (Å) between Li⁺ and anionic moiety of the ZPE. Atoms are colored differently according to the element type: carbon (gray), nitrogen (blue), sulfur (yellow), hydrogen (white), oxygen (red), and fluorine (sky blue), respectively. d RDF analysis of ZM(TFSI⁻) (vs. ZM(SO₃⁻))−Li⁺ in the ZPE. e, f WAXS (e) and solid-state ⁷Li NMR spectra (f) of the ZPE(TFSI^–) (vs. ZPE(SO₃^–)). The inset shows the inversion-recovery plots obtained from the solid-state ⁷Li NMR analysis. g Li⁺ conductivity (\(\sigma\)_Li+) as a function of temperature and activation energy (E_a) of the ZPE(TFSI^–) (vs. ZPE(SO₃^–)).