Ion Reservoir Enabled by Hierarchical Bimetallic Sulfides Nanocages Toward Highly Effective Sodium Storage

Designing and constructing bimetallic hierarchical structures is vital for the conversion‐alloy reaction anode of sodium‐ion batteries (SIBs). Particularly, the rationally designed hetero‐interface engineering can offer fast diffusion kinetics in the interface, leading to the improved high‐power surface pseudocapacitance and cycling stability for SIBs. Herein, the hierarchical zinc–tin sulfide nanocages (ZnS‐NC/SnS₂) are constructed through hydrothermal and sulfuration reactions. The unconventional hierarchical design with internal void space greatly optimizes the structure stability, and bimetallic sulfide brings a bimetallic composite interface and N heteroatom doping, which are devoted to high electrochemical activity and improved interfacial charge transfer rate for Na⁺ storage. Remarkably, the ZnS‐NC/SnS₂ composite anode exhibits a delightful reversible capacity of 595 mAh g^?1 after 100 cycles at 0.2 A g^?1, and long cycling capability for 500 cycles with a low capacity loss of 0.08% per cycle at 1 A g^?1. This study opens up a new route for rationally constructing hierarchical heterogeneous interfaces and sheds new light on efficient anode material for SIBs.