Lithium metal battery (LMB) is a potential next-generation battery that can provide higher energy density than Li-ion batteries. However, during fast charging, lithium dendrites growth occur at the surface of Li metal anode, resulting in short circuiting, thermal runaway, and fire event. Under high-voltages beyond 4.2 V, lithium dendrites growth and structural degradation of cathode active material will be accelerated, leading to faster performance fade and higher risk of short circuiting. Herein, we demonstrate the significant impacts of fluorinated organic additive that enables ultrafast charging 400 cycles performance of Li//Mn-rich LMB under extreme conditions of 20 C (charged in 3 minutes) and charge cut-off voltage of 4.8 V, without lithium dendrites. Stable performance and high tolerance to extreme conditions are ascribed to the additive-derived formation of uniform and robust solid electrolyte interphase (SEI) layers at Li metal anode and Mn-rich cathode. Studies of the correlation between SEI stability, performance, and battery safety will be discussed in the meeting. Acknowledgements This research was supported by the Ministry of Trade, Industry & Energy (20007034) and National Research Foundation grant funded by the Ministry of Science and ICT (2019R1A2C1084024 & RS-2023- 00217581) of Korea.