Minimal TiO<sub>2</sub> Coupled with Conductive Polymer-Stimulated Synergistic Effect on Fast and Reversible Sodium-Ion Storage for Bismuth Sulfide
Hui Guan, Xin Du, Yuhao Yi, Xiyang Kang, Kai Li, Xiangdong Pei, Zhipeng Zhao, Jianmin Zhang, Dan Li
Abstract
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.