Electrolyte design has become ever more important to enhance the performance of lithium-ion batteries (LIBs). However, the flammability issue and high reactivity of the conventional electrolytes remain a major problem, especially when the LIBs are operated at high voltage and extreme temperatures. Herein, we design a novel non-flammable fluorinated ester electrolyte that enables high cycling stability in wide-temperature variations (e.g., −50 °C–60 °C) and superior power capability (fast charge rates up to 5.0 C) for the graphite||LiNi0.8Co0.1Mn0.1O2 (NCM811) battery at high voltage (i.e., >4.3 V vs. Li/Li+). Moreover, this work sheds new light on the dynamic evolution and interaction among the Li+, solvent, and anion at the molecular level. By elucidating the fundamental relationship between the Li+ solvation structure and electrochemical performance, we can facilitate the development of high-safety and high-energy-density batteries operating in harsh conditions.