Na₂O Inorganic Solid Electrolyte Interface Mediated Through Electrode Structure Engineering Enabling Outstanding Sodium‐Storage Performance for Transition‐Metal Selenide Anodes

Abstract Transition‐metal selenides hold great promise as advanced anode candidates for fast‐charging sodium‐ion batteries. However, an unstable solid electrolyte interphase (SEI) caused by their enormous volume expansion and strong catalytic action results in the continuous degradation of their sodium‐storage performance with cycling. Herein, a novel structure with carbon nanotubes bridging the adjacent layers of Mxene is constructed for host material, which can enrich the transport paths of electrons and ions within the electrode triggering a two‐electron reaction during the electrolyte decomposition, thereby tailoring an ultrathin and robust SEI rich in Na 2 O inorganic component. Thus the prepared anode demonstrates the improved initial Coulombic efficiency (87%) and cycling lifespan (442.9 mAh g −1 at 5 A g −1 after 1470 cycles). Meanwhile, it delivers a high‐rate capacity of 394.3 mAh g −1 at up to 20 A g −1 , and accomplishes capacity retention above 90% as the current density transitions from 10 to 20 A g −1 . Even when the current density increases to 5 A g −1 for 1470 cycles, the capacity retention is still higher than 90%. This study illustrates the feasibility of tailoring SEI components through electrode structure engineering and opens a new avenue to the controllable modulation of electrode‐electrolyte interfacial chemistry.