Multiphase Inorganic-Rich Interphases with Integrated Li-Ion Capture-Transport Ability for High-Rate Lithium Metal Batteries

Abstract Lithium metal batteries promise high-energy-density storage but are limited by unstable solid–electrolyte interphases, which couple poor passivation, sluggish Li+ transport, dendritic deposition, and safety risks. Herein, we report a multiphase inorganic-rich solid–electrolyte interphase (m-SEI) containing P- and Al-derived species including Li3P, LiAl5O8, Li3PO4, and Li2Al, which is formed from the in situ reaction between a flame-retardant aluminum diethyl hypophosphite (ADP) interlayer and lithium metal. This multicomponent inorganic SEI enables an integrated capture-transport mechanism by combining high Li+ affinity, facilitated desolvation, and low-barrier Li+ migration pathways in individual inorganic phases and their heterophase interfaces, thereby facilitating rapid Li+ interfacial migration. Its chemical inertness and high Young’s modulus of 17.14 GPa further suppress electrolyte decomposition and Li dendrite growth. As a result, the Li-metal batteries with m-SEI deliver an extended lifespan of 1000 h at a high current density of 4 mA cm–2. Li||NCM811 full cells with a high cathode loading (20 mg cm–2) and ultrathin Li foil (50 μm) retain 80% capacity after 250 cycles, while Li||NCM811 pouch cells retain 90% capacity after 500 cycles. This work establishes the capture-transport mechanism as an effective design principle for regulating Li+ interfacial dynamics and offers a practical interphase-engineering strategy for constructing ion-conductive and chemically protective interphases in durable lithium metal batteries.