Ferroelectric Dipole-Driven Solid-Electrolyte Interphase Passivation for High-Voltage Lithium Metal Batteries

High-voltage lithium (Li) metal batteries (LMBs) are regarded as strong candidates for next-generation high-specific-energy storage devices. However, interfacial side reactions (ISRs) (particularly the often-overlooked chemical corrosion) and Li dendrite lead to severe depletion of active Li and even pose safety hazards, significantly hindering the practical applications of LMBs. Herein, an oxygen-vacancy-engineered BaTiO₃ pre-adsorbed with NO₃ ^- (BTOVN) layer is integrated onto a polypropylene separator to selectively lower the energy level of target anion via ferroelectric dipoles, thus passivating the anode/electrolyte interface and improving the long-term storage and cycle stability of LMBs. Combining cryo-electron microscopy with multi-scale spectroscopies, we reveal that the ferroelectric BTOVN layer targets NO₃ ^- to the interface and promotes the reductive decomposition of both NO₃ ^- and PF₆ ^- to form a thinner and tougher solid-electrolyte interphase (SEI) rich in inorganic Li₂O, Li₃N, and LiF, which effectively suppresses persistent ISRs and Li dendrite proliferation while enhancing Li⁺ transport kinetics and interfacial stability. As a result, high-voltage Li metal full cells delivery a substantially enhanced capacity retention of 89.1% after 500 cycles, and remarkably, even after long-term resting, they maintain exceptionally stable operation. The work provides a novel perspective on precisely engineering SEI chemistry through targeting anionic species into the interphase layer.