Described
herein presents a class of novel deep eutectic electrolytes
(DEEs) with distinctive properties for sodium batteries. Instead of
being limited by the presence of a hydrogen bond donor (HBD) or hydrogen
bond acceptor (HBA), the concept of Na···N interactions
was first brought in between sodium bis(fluorosulfonyl)imide (NaFSI)
and 1,2-dimethylimidazole (DMIm). The deep eutectic phenomenon was
caused by the strong ion–dipole interaction, which was conducive
to the release of Na+ from NaFSI and drove the DEE with
a desirable ionic conductivity. Furthermore, the proposed mechanism
of Na···N interactions was credibly confirmed by Raman, 23Na NMR, and theoretical calculations. The half-cell based
on NaFSI/DMIm–1/4 can provide a reversible capacity of 316.7
mAh·g–1 at 0.05 A·g–1, and Coulombic efficiency remains 91% after 500 charge–discharge
cycles at 1.0 A·g–1 in the application of sodium
batteries. It is anticipated that this work will present distinct
insights into the extension of electrolytes for sodium batteries.