Reactivity‐Driven Metal‐Adaptive Interphases for Dendrite‐Free, High‐Rate Alkali Metal Anodes

Abstract

Abstract Alkali metal anodes (e.g., Li and Na) require a solid‐electrolyte interphase (SEI) customized to their physicomechanical and electrochemical demands; however, conventional SEI designs relying on generic “one‐size‐fits‐all” approaches fail to fully address the metal‐specific requirements. Herein, a metal‐adaptive SEI reconstruction strategy is proposed to leverage the reactivity‐guided diisopropoxy‐bisethylacetoacetatotitanate (DPBT) coatings on alkali metal anodes (TC‐Li/TC‐Na). The resulting interphases both share a hierarchical architecture with an ultrathin titanate layer and a TiO 2 ‐based inner matrix connected through compositionally graded segments (Ti–O–M, M = Li/Na/C), yet demonstrate metal‐specific structural differentiation. The moderate reactivity of Li facilitates the dense packing of larger TiO 2 nanoparticles, forming a low‐porosity, high‐modulus layer that mechanically suppresses dendrites. Conversely, the more rapid reaction of Na instantly produces abundant gas bubbles and fosters a highly porous network with interconnected ultrasmall TiO 2 nanoparticles, integrating moderate modulus with elevated surface roughness that dynamically accommodates volumetric strain and enhances interfacial activity. Consequently, the NCM811||TC‐Li pouch cell achieves high‐capacity retention (89.3%, 200 cycles, 456.8 Wh kg −1 ) under 0.2 C/0.5 C and stable operation under high capacity and high energy density of 11.1 Ah and 550.2 Wh kg −1 , while NFM||TC‐Na pouch cell deliveries exceptional cycling stability at 0.3 C/1 C (79.7% retention over 200 cycles).