Conformational Engineering of Solvent Molecules for High-Voltage and Fast-Charging Lithium Metal Batteries.

High-voltage and fast-charging lithium metal batteries (LMBs) are crucial for overcoming electric vehicle range and charging limitations. However, conventional carbonate electrolytes face intrinsic limitations in simultaneously achieving compatibility with high-voltage cathodes and lithium metal anodes. These limitations arise from sluggish Li transport kinetics and parasitic side reactions, both largely driven by excessive Li solvation energy inherent to carbonates. To address these challenges, we propose a conformational engineering strategy of fluorinated solvent molecules by developing a 2,2,3,3,4,4-hexafluoropentanedioic·anhydride (HFPA)-derived electrolyte (HFPE). The chair conformation of HFPA synergizes with its high F/C ratio to establish a low-polarity solvation environment, effectively reducing desolvation energy barriers. In addition, the HFPA-induced ligand preference for anion aggregation contributes to the formation of anion-rich dissolved sheaths while stabilizing the electrode-electrolyte interphases. The engineered HFPE demonstrates accelerated interfacial ion transport kinetics with an enhanced Li transference number of 0.64. When paired with LiNiCoMnO cathodes under stringent operating conditions (4.5 V cut-off voltage, 10 C-rate), HFPE-enabled cells exhibit exceptional cycling stability. Notably, industrial-scale 5.6 Ah lithium metal pouch cells employing HFPE maintain stable operation at 4.5 V, underscoring the practical viability of this conformation modulation approach. This work establishes a paradigm-shifting strategy for next-generation electrolyte design in practical high-energy-density LMBs.