Time‐Domain Regulation of Electrolyte Microenvironments Enables 30 mA cm − 2 Stable Lithium Plating/Stripping for High‐Voltage Lithium Metal Batteries

ABSTRACT The practical application of high‐voltage lithium metal batteries (LMBs) is severely hindered by interfacial instability and structural degradation, fundamentally originating from “time‐domain mismatch” between rapid parasitic reactions and sluggish interface passivation. Herein, we propose a time‐domain responsive in situ gel polymer electrolyte (SiNCO‐GPE) to dynamically regulate the electrolyte microenvironment. The (trimethylsilyl)isocyanate (SiNCO) acts as a “scavenging cage” to eliminate trace water and hydrogen fluoride, while its reaction products subsequently participate in interfacial evolution. The in situ polymerized poly(vinylene carbonate) integrated with poly(vinylidene fluoride‐co‐hexafluoropropylene) electrospun fiber skeleton creates a F‐O co‐coordination environment to facilitate fast Li + transport. The electroactive isocyanate group in SiNCO, together with lithium difluoro(oxalato)borate and fluoroethylene carbonate, decomposes preferentially to rapidly construct a robust B/N/F‐rich interphase layer during initial cycling on both the anode and cathode, while the Si‐containing scavenging products are dynamically incorporated into the interphase layers during prolonged cycling to accommodate mechanical stress. The SiNCO‐GPE enables exceptional Li plating/stripping stability for over 4000 h at 1 mA cm − 2 and withstands an ultrahigh current density of 30 mA cm − 2 over 70 h, while the Li||LiNi 0.8 Co 0.1 Mn 0.1 O 2 cell delivers an outstanding capacity retention of 90.5% after 500 cycles at 4.7 V, offering new insights into the development of durable high‐voltage LMBs.