A Weak-Aggregation Electrolyte Enables Lithium-Ion Capacitors at Ultra-Low Temperature

The operation of low-earth orbit satellites, Antarctic research stations, and certain extreme cold environments demands energy storage devices (ESDs) capable of functioning at -100°C or lower. Conventional electrolytes are limited by sluggish ion transport and unstable electrode-electrolyte interphases at low temperatures, severely degrading the performance of electrochemical ESDs under extreme cold. Herein, we report a weak-aggregation (AGG-w) electrolyte reconciling bulk-phase ion transport with interfacial kinetics at ultra-low temperatures (ULT). This is achieved through the strategic incorporation of unilaterally fluorinated motif as strong electron-withdrawing group, which enhances steric hindrance and reconfigure molecular dipole to reinforce dipole-dipole interaction with the solvents anchored in the primary solvation shell. Such restructuring enables unprecedented solvent-anion cooperativity by weakening Li⁺-dipole interaction and promoting greater anion participation, thereby accelerating desolvation kinetics, reducing interfacial resistance, and simultaneously preserving low viscosity and high ionic conductivity at ULT. Notably, 1100 F real pouch cells with AGG-w electrolyte maintain 97.9% capacity retention after 7 months of continuous operation at -40°C and demonstrate emerging discharge capability at -100°C, a milestone never previously reported. This work underscores weak-interaction engineering as a critical paradigm for electrolyte design and establishes a generalizable strategy for high-performance electrochemistry in extreme conditions.