Overcoming the Electrolyte-Derived Interphase Through Sequential Reactions for Stable Lithium Metal Anode

Lithium metal batteries hold significant promise for achieving energy densities beyond 400 Wh kg-1. However, the uncontrolled decomposition of solvent molecules and salt anions leads to a heterogeneous electrolyte-derived solid electrolyte interphase (SEI), resulting in nonuniform Li-ion diffusion and uncontrolled dendrite growth, which severely compromises cycling stability. Herein, we propose a sequential reactions strategy that enables precise SEI regulation through finely controlled chemical and electrochemical processes, overcoming the limitations of conventional electrolyte-driven decomposition. A reactive polymer, sulfurized polyethylenimine, is designed to chemically induce the formation of an Li2S layer on the lithium metal surface, ensuring homogeneous Li-ion transport. Subsequently, a Li2S/Li3N intermediate layer, generated by electrochemical reactions, accelerates Li-ion migration. Shielded by the unreacted organic layer, the tailored SEI maintains robust structural integrity. Even under lean electrolyte (1.35 g Ah-1) and high areal capacity (6.0 mAh cm-2), a 3.4 Ah LiNi0.8Co0.1Mn0.1O2||Li pouch cell employing this well-controlled SEI achieves an ultrahigh specific energy of 480.5 Wh kg-1 with an impressive capacity retention of 85.9% after 100 cycles. These findings provide a new paradigm for rational SEI design via the regulation of sequential reactions, offering valuable insights into stabilizing Li metal anodes under practical conditions.