Orderly Arranged Dipoles Regulate Anion‐Derived Solid–Electrolyte Interphase for Stable Lithium Metal Chemistry

Abstract Lithium (Li) metal batteries are considered the most promising high‐energy‐density electrochemical energy storage devices of the next generation. However, the unstable solid–electrolyte interphase (SEI) derived from electrolytes usually leads to high impedance, Li dendrites growth, and poor cyclability. Herein, the ferroelectric BaTiO 3 with orderly arranged dipoles (BTOV) is integrated into the polypropylene separator as a functional layer. Detailed characterizations and theoretical calculations indicate that surface oxygen vacancies drive the phase transition of BaTiO 3 materials and promote the ordered arrangement of dipoles. The strong dipole moments in BTOV can adsorb TFSI − and NO 3 − anions selectively and promote their preferential reduction to form a SEI film enriched with inorganic LiF and LiN x O y species, thus facilitating the rapid transfer of Li + and restraining the growth of Li dendrites. As a result, the Li–Li cell with the BTOV functional layer exhibits enhanced Li plating/stripping cycling with an ultra‐long life of over 7000 h at 0.5 mA cm −2 /1.0 mAh cm −2 . The LiFePO 4 || Li (50 µm) full cells display excellent cycling performance exceeding 1760 cycles and superior rate performance. This work provides a new perspective for regulating SEI chemistry by introducing ordered dipoles to control the distribution and reaction of anions.