Tidal Mixed Ionic/Electronic Conductive Interlayer Enables Supersmooth Lithium Deposition for Stable Lithium Metal Batteries

Abstract Lithium metal is the ultimate anode material for Li‐based battery chemistries with high energy density. However, inhomogeneous charge distribution derived from the unbalanced ion/electron transport is usually generated at the electrode/electrolyte interface, leading to uncontrollable dendrite growth with poor reversibility. Herein, a mixed ionic/electronic conductive (MIEC) interlayer activated from the in situ conversion and nano‐alloying reactions between the sputtered AlN arrays and metallic Li is efficiently constructed on the Li surface via facile mechanical calendaring. The 3D interconnected polyimide scaffolds with the extensive Li 3 N/Li 9 Al 4 dual‐decoration promote charge redistribution while enhancing electrochemical kinetics. The significantly reduced nucleation/plateau overpotentials, the overwhelming bottom‐up lithium growth pattern derived from the tidal MIEC interlayer, combined with the inorganics‐dominating solid electrolyte interphase synergistically regulates the uniform Li nucleation/growth. As demonstrated, a prolonged lifespan of the symmetric cell over 7500 h with an ultralow polarization of 12 mV is achieved at 5 mA cm −2 @5 mAh cm −2 , further improving the rate capability and cycling performance of LiFePO 4 ‐based practical full cells with a capacity retention of 85.4% after 220 cycles. The proposed approach is also applicable to match the roll‐to‐roll production process, presenting an efficient strategy to realize the high‐performance composite anode of industry‐adaptable potential.