Achieving Rapid Ultralow-Temperature Ion Transfer via Constructing Lithium-Anion Nanometric Aggregates to Eliminate Li + -Dipole Interactions.

Sluggish desolvation in extremely cold environments caused by strong Li ⁺ -dipole interactions is a key inducement for the capacity decline of a battery. Although the Li ⁺ -dipole interaction is reduced by increasing the electrolyte concentration, its high viscosity inevitably limits ion transfer at low temperatures. Herein, Li ⁺ -dipole interactions were eliminated to accelerate the migration rate of ions in electrolytes and at the electrode interface via designing Li ⁺ -anion nanometric aggregates (LA-nAGGs) in low-concentration electrolytes. Li ⁺ coordinated by TFSI ^- and FSI ^- anions instead of a donor solvent promotes the formation of an inorganic-rich interfacial layer and facilitates Li ⁺ transfer. Consequently, the LA-nAGG-type electrolyte demonstrated a high ionic conductivity (0.6 mS cm ^-1 ) at -70 °C and a low activation energy of charge transfer (38.24 kJ mol ^-1 ), enabling Li||NiFe-Prussian blue derivative cells to deliver ∼83.1% of their room-temperature capacity at -60 °C. This work provides an advanced strategy for the development of low-temperature electrolytes.