Ordering Sulfonic Groups Facilitate a Li₃N‐Enriched Interphase via Directing the Decomposition of LiNO₃

Abstract The practical application of high‐energy lithium (Li) metal anodes is plagued by the severe issues of interfacial instability. The Li₃N originated from the decomposition of LiNO₃ is believed to endow the solid electrolyte interphase (SEI) with high stability and ionic conductivity. However, the precise control on the decomposition of LiNO₃ is still challenging due to the sophisticated reaction pathways and high energy barriers. In this study, a self‐assembled monolayers (SAMs) with densely packed and long‐range ordered sulfonic acid groups on an alumina‐coated separator are designed. By providing a strong dipole moment, this SAMs efficiently facilitate the rapid and deep decomposition of LiNO₃, leading to the formation of an SEI rich in Li₃N nanocrystals. Notably, under the stringent conditions of 5 mA cm⁻² and 5 mAh cm⁻², the Li/Li symmetric cell is still able to cycle stably for 1000 h under the stable nitrided interface induced by the SAMs. Consequently, the application scenarios of SAMs technology in precisely controlling electrolyte decomposition processes are successfully expanded to stabilize the interphase of metallic Li anode with high energy‐density.