Synergizing Interfacial Electric Field Regulation and In‐situ Robust Interphases for Stable Lithium Metal Batteries at High Currents

Efficient cycling of lithium (Li) metal batteries (LMBs) under extremely high current conditions is critical for their practical applications. Here, we report a novel additive containing fluorine, nitrogen, and iodine elements (designated as FCS) to stabilize Li metal anodes in glyme‐based ether electrolytes under high current conditions. Experimental results and molecular dynamics (MD) simulations demonstrate that the cation of FCS selectively adsorbs on the electrode surface, optimizing the inner Helmholtz plane (IHP) structure and effectively regulating the surface electric field, thereby promoting homogeneous Li deposition. Simultaneously, the preferential decomposition of the FCS produces a mechanically robust and ionically conductive solid electrolyte interphase (SEI) comprising LiF, Li3N, and LiI components. Consequently, with the FCS additive, Li||Cu cells demonstrate a remarkably average Coulombic efficiency (CE) of 98.12% at an extremely high current of 20 mA cm−2 over 400 cycles. Additionally, Li||SPAN cells maintain a reversible capacity of 1126 mAh g−1 at 0.5 A g−1 after 200 cycles. This work presents a new approach to simultaneously tune the Helmholtz plane and SEI using trace amounts of additive, paving the way for stable and efficient LMBs under high‐current conditions.