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

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 Bi₂S₃ nanorods, is demonstrated to construct the multiphase composition involving TiO₂ coating and polypyrrole (PPy) encapsulation. Bi₂S₃ acted as the dominating active material, in consideration of the low content of TiO₂, which ensured the high capacity of the composite. The dual-structural restrain of the TiO₂ and PPy coatings can effectively alleviate volume variation based on the pseudo-"zero-strain" effect of TiO₂ and high flexibility of PPy shells. Meanwhile, the heterointerface greatly enhanced the coupling effect between Bi₂S₃ and TiO₂ 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 Bi₂S₃/TiO₂ heterojunction and the dual-structural restrain effect, the Bi₂S₃/TiO₂@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.