Robust Interfacial Chemistry Induced by B‐Doping Enables Rapid, Stable Sodium Storage

Abstract Constructing a stable solid electrolyte interphase (SEI) at the electrode–electrolyte interface is powerful for optimizing the battery performance. However, studies related to interface chemistry have particularly focused on engineering electrolytes and overlooked regulating electrode materials. Here, this study reports that the B‐doped Bi interconnected nanoparticles (B─Bi) are prepared by a facile and effective chemical reduction reaction. The B doping helps to catalyze the electrolyte decomposition and more NaF formation on the electrode surface, which facilitates a stable uniform SEI with enhanced mechanical stability. Such a robust SEI layer can inhibit the further decomposition of electrolytes and promote the interfacial Na + transfer. The B─Bi offers a reversible capacity of 403.1 mAh g −1 at 1.0 A g −1 and a high rate capability of 203 mAh g −1 at 80 A g −1 . Moreover, the B‐doping method also finds its viability to stabilize SEI in Sb material. This study demonstrates a new strategy for engineering the interface chemistry toward stable SEI and excellent performance.