The Restrained Li/Gel Polymer Electrolyte Interface Deterioration Enabled by the Synergetic Effect of Ultra‐Lithiophilic Interphase and Interfacial Coupling Skeleton

Abstract Quasi‐solid‐state lithium metal batteries are deemed as one of the most promising next‐generation energy storage devices due to their enhanced safety and high energy density. However, the Li/Gel polymer Electrolyte (GPE) interface deterioration induced by the side reactions, dendrite growth during Li plating, and contact loss during Li stripping will inevitably lead to the failure of the battery. Herein, a Li/Li₂₃Sr₆–Li₃N/Sr₂N anode structure (LSN) prepared by hot‐rolling process is designed, where Sr₂N serves as an inert skeleton to retain the interfacial coupling and to avoid contact loss. At the same time, the Li₃N–Li₂₃Sr₆ interphase with high Li adsorption energy and fast Li⁺ transfer kinetics regulate the Li plating behavior. Benefitting from the design, when coupled with the carbonate‐based GPE, the lifespan of the symmetric battery with the LSN is extended to 1300 h at 0.2 mA cm⁻²/0.2 mAh cm⁻². Furthermore, the LSN||LiFePO₄ (LFP) full cell exhibits a steady cycle with extremely low voltage polarization at 0.5 C after 200 cycles. This study provides a practical strategy to stabilize the Li/GPE interface and deepens the understanding of Li⁺ plating/stripping behaviors through the interphase.