Nitrile–Ether Intramolecular Hybridization Enables Fast-Charging and Wide-Temperature Lithium-Ion Batteries

Abstract

Acetonitrile-based electrolytes offer excellent bulk transport for high-rate lithium-ion batteries but suffer from poor reductive stability and interfacial incompatibility. Here, we propose an intramolecular hybridization strategy using 3-ethoxypropionitrile (EPN) as an ideal solvent. Incorporation of an ether moiety into the nitrile backbone modulates charge distribution and enhances reductive stability, while steric hindrance promotes an anion-enriched weak-solvation structure. The integrated functional groups also impart amphiphilicity to the solvent, improving wettability toward both the separator and electrodes. This tailored molecular environment facilitates the formation of ultrathin, inorganic-rich interphases on both electrodes, enhancing interfacial stability and ion-transport kinetics. Consequently, EPN-based electrolytes enable 10 C fast-charging and stable operation from −20 to 55 °C. Notably, practical 1 Ah Graphite||LiFePO4 pouch cells retain 83.2% capacity after 1000 cycles at 1 C and 88.6% after 500 cycles at 3 C, demonstrating the promise of molecularly engineered nitrile electrolytes for fast-charging batteries.