In situ Catalytic‐Conversion Reaction Driven Gradient Lipophilic‐Lipophobic Fluorine‐Rich Multiphase Interphase Design for all‐Solid‐State Lithium Metal Batteries

ABSTRACT All‐solid‐state lithium‐metal batteries utilizing inorganic solid electrolytes are viewed as a promising alternative for electrochemical energy storage systems. Nevertheless, compatibility issues as for the anode‐electrolytes interface hinder their practical implementation due to the uncontrollable Li dendrite growth and undesirable side reactions. By regulating the reaction pathways, the composition and structure of the interface can be precisely tailored, thereby enhancing the anode interface compatibility. Here, a gradient F‐rich multiphase interphase was constructed through precise control over the in situ “catalytic conversion” reactions of metal fluorides at the Li/electrolyte interface. Through advanced characterization and detailed calculation, we found that metal fluorides can act as catalytic centers, promoting the dissociation of lithium salts due to the strong Lewis acid‐alkali base electrostatic interaction. Subsequently, Li‐alloy phases were generated through thermodynamic spontaneous reaction at low potentials. Finally, the gradient lipophilic‐lipophobic SEI composed of co‐grown LiF, Li 3 N, and Li‐alloy effectively enhances the Li + transport and promotes uniform Li + flux. The reaction driven F‐rich multiphase SEI enable the Li symmetric cell an impressive CCD performance of up to 4.6 mA cm −2 , and the NCM811/Li full cell an excellent cycling performance with a capacity retention of 80.4% after 800 cycles, demonstrating the practical application potential in energy storage field.