Highly Stable Sodium Metal Batteries Enabled by Manipulating the Fluorinated Organic Components of Solid‐Electrolyte‐Interphase

Abstract Na metal batteries (NMBs) stand at the forefront of advancing energy storage technologies, but are severely hampered by Na dendrite issues, especially when using carbonate electrolytes. Suppressing the growth of Na dendrites through constructing NaF‐rich solid‐electrolyte‐interphase (SEI) is a commonly‐used strategy to prolong the lifespan of NMBs. In contrast, fluorinated organic SEI components are often underutilized. Inspired by unveiling the adsorption configuration of fluorinated organic compounds on the surface of Na metal, an optimized SEI architecture for stabilizing NMBs is proposed by investigating the C 4 H 9 SO 2 F‐/C 4 F 9 SO 2 F‐treated Na metal anodes. It is revealed that the SEI built on a fluorinated inorganic/organic hybrid layer exhibit favorable Na passivation capability, significantly improving Na deposition behavior. As a result, the NMB with a high‐loading cathode (15 mg cm −2 ) and a negative/positive capacity ratio (N/P) ratio of 4 shows a long‐term life span over 1000 cycles with 92.8% capacity retention at 2 C. This work opens a new pathway for developing robust and high‐energy‐density NMBs.