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

ABSTRACT 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 BaTiO 3 pre‐adsorbed with NO 3 − (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 NO 3 − to the interface and promotes the reductive decomposition of both NO 3 − and PF 6 − to form a thinner and tougher solid‐electrolyte interphase (SEI) rich in inorganic Li 2 O, Li 3 N, 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.