Heterostructure SnSe2/ZnSe@PDA Nanobox for Stable and Highly Efficient Sodium‐Ion Storage

Abstract Rationally designed electrode materials with high capacity, long cycle life, and low cost are indispensable for sodium‐ion batteries. Herein, a hierarchical nanobox consisting of a heterojunction bimetallic selenide yolk and polydopamine shell (denoted as SnSe 2 /ZnSe@PDA) is engineered and fabricated successfully. Owing to the charge redistribution and lattice distortion at the hetero‐phase boundaries, Na + ions can be easily adsorbed and transferred swiftly, facilitating the reaction kinetics and promoting cycling behavior. By means of the hollow structure and elastic polymer shell, this approach can synergistically alleviate volume fluctuation and the aggregation of active nanomaterials during cycling. This material delivers a high reversible capacity of 616 mA h g ‐1 at 1 A g ‐1 over 1000 long‐term cycles, and superior rate capability, which provides more possibilities for the practical applications of energy storage in the future.