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) at -70 °C and a low activation energy of charge transfer (38.24 kJ mol), 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.