Minimal TiO₂ Coupled with Conductive Polymer-Stimulated Synergistic Effect on Fast and Reversible Sodium-Ion Storage for Bismuth Sulfide

Designing multiphase composition is believed to availably boost the structural integrity and electrochemical properties of sodium-ion battery anodes. Herein, a conceive of nanoflowers, assembled with Bi 2 S 3 nanorods, is demonstrated to construct the multiphase composition involving TiO 2 coating and polypyrrole (PPy) encapsulation. Bi 2 S 3 acted as the dominating active material, in consideration of the low content of TiO 2, which ensured the high capacity of the composite. The dual-structural restrain of the TiO 2 and PPy coatings can effectively alleviate volume variation based on the pseudo-“zero-strain” effect of TiO 2 and high flexibility of PPy shells. Meanwhile, the heterointerface greatly enhanced the coupling effect between Bi 2 S 3 and TiO 2 and thus improved the electrochemical performance, which was proved by the results of density functional theory calculation and electrochemical tests. Combining the regulation from the Bi 2 S 3 /TiO 2 heterojunction and the dual-structural restrain effect, the Bi 2 S 3 /TiO 2 @PPy electrode exhibited excellent rate performance and superior cycle stability (275.8 mA h g –1 over 500 cycles at 10 A g –1 ). This study indicates that designing multiphase composition can be very promising and provides a structural insight to construct high stability in electrodes for sodium-ion batteries.