Bi₂S₃ Nanorods Deposited on Reduced Graphene Oxide for Potassium-Ion Batteries

Abstract

Hierarchical nanocomposites with surface active bonding features serve as an efficient electrode material for high-performance Li-/Na-/K-ion batteries. Tuning the physiochemical properties of these hierarchical nanocomposites has a great impact on the extremely improved electrochemical performance, and it is attributed to the synergistic effect of heterogeneous components. Herein, we report a hydrothermally synthesized bismuth sulfide (Bi 2 S 3 ) nanorod bonding on the surface of the reduced graphene oxide (rGO) matrix and investigate it as an anode material for potassium-ion batteries. This hierarchical nanocomposite anode exhibits a high initial reversible capacity (586 mA h g –1 at 100 mA g –1 ), long-term cycling stability (410 mA h g –1 after 1000 cycles, 70% capacity retention), and an outstanding rate capability (140 mA h g –1 at 3 A g –1 ). This excellent electrochemical performance of the Bi 2 S 3 /rGO nanocomposite is attributed to the presence of active sites in rGO nanosheets that not only enhances the electrical conductivity of Bi 2 S 3 nanorods but also prevents the shuttle effect of polysulfide through the formation of the in-built C–S bond, which is confirmed by X-ray photoelectron spectroscopy. Through the ex-situ X-ray diffraction patterns analysis at different voltage regions, a phase transformation mechanism has been proposed for K-ion storage in Bi 2 S 3 nanorods. An ex-situ high-resolution transmission electron microscopy analysis reveals the structural and morphological stability of Bi 2 S 3 nanorods. Further, the kinetic studies confirmed that the surface dominated pseudocapacitive K-ion storage also plays a major role in improving the electrochemical performance of the Bi 2 S 3 nanorods/rGO nanocomposite. The K-ion full cell is successfully assembled, which exhibits stable cycling performance after 100 cycles at 1 C rate.

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