Compact Ion-Pair Aggregates Dominated Electrolytes Enable High-Performance Low-Temperature Lithium-Ion Batteries.

Lithium-ion batteries (LIBs) are widely used due to their high energy density, long cycle life, and environmental friendliness. However, at sub-zero temperatures, the operation of LIBs is constrained by degraded electrolyte ion transport performance and severe charge transfer polarization. In this work, we proposed a strategy for the construction of solvation structures dominated by compact ion-pair aggregates (CIPAs) through weak lithium-solvent interactions design, which significantly improved the lithium-ion transference number and reduced the de-solvation energy barrier. Excitingly, this strategy can induce the formation of a robust anion-derived solid electrolyte interface, thereby enabling the rapid transport of lithium ions across the interface even at extremely low temperatures. This electrolyte provides excellent electrochemical performance of practical natural graphite and LiNiCoMn (NCM811) electrodes. The NCM811||graphite full cell exhibits capacity retention of 84.7% of its room temperature capacity at a high rate of 0.5C at -20 °C, and can be cycled stably for over 200 cycles at -40 °C without obvious capacity degradation. This work presents an innovative avenue for high performance LIBs at low temperature.