The synthesis, spectroscopic and electrochemical characterization of Li[N(SiMe3)(SO2RF)] (RF=CF3, n‐C4F9) as well their behavior as electrolyte additive in lithium ion batteries (LIBs) is reported. The lithium salts were obtained by deprotonation of the corresponding acids HN(SiMe3)(SO2RF) with n‐butyllithium in n‐pentane. The electrochemical investigations suggested potential as additives for LIBs. Thus, NCM111/graphite cells (NCM111=Li[Ni0.33Co0.33Mn0.33]O2) with LP57 as electrolyte (LP57=1.0 M LiPF6 in EC/EMC 3 : 7) were built to test the performance. Cells with Li[N(SiMe3)(SO2RF)] as additives show coulombic efficiencies of over 99.6 %, less capacity fading over 55 cycles and a significantly lower cell impedance built up
