Harnessing Spatiotemporal Dynamics of Polymerized Electrolytes for Durable High-Voltage Lithium Metal Batteries

Despite affording conformal interfaces in solid-state and quasi-solid-state Li metal batteries (LMBs), <i>in situ</i> polymerized electrolytes suffer from sluggish Li⁺-transport kinetics and chemically reactive interphases that promote electrolyte decomposition and parasitic side reactions in high-voltage LMBs. Herein, we report spatiotemporally engineered <i>in situ</i> polymerized electrolytes (S-IPEs) that simultaneously resolve both challenges, enabling durable high-voltage high-Ni-cathode-based full-cell performance. Based on theoretical and experimental analyses, we demonstrate that spatially programmed component distributions of nitrate ions, fluoropolymer, and polymeric ester-based electrolyte drive self-optimized spatiotemporal interfacial chemistry. Within the fluoropolymer framework, anion-preferential adsorption establishes durable anion-rich and polymeric-electrolyte-lean interfacial dynamic reconstruction, achieving robust antioxidative interface. At the same time, persistent nitrate release from the cathode side decouples bulk Li⁺ transport from the polymer matrix, affording fast ion-transport kinetics and sustained optimization of the Li-metal anode interface. The resultant S-IPEs realize stable electrochemical performance at high current densities and cathode loadings (2 mA cm^-2; high-voltage LiNi_0.8Co_0.1Mn_0.1O₂ cathodes of 3.31 mAh cm^-2). This work establishes an effective spatiotemporal regulation of interfacial chemistry and bulk ion-transport kinetics, providing a new benchmark for the practical realization of solid-state LMBs.