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.