Bi@C Core-Shell Nanostructure as Anode for Sodium-Ion Batteries from One-Step Arc Discharge

Abstract

Bismuth has a great potential as the anode for sodium-ion batteries (SIBs) because of the layered structure with large interlayer space, long mean free path, and high volumetric capacity. In this paper, carbon-coated bismuth (Bi@C) core-shell nanostructure has been in situ synthesized by one-step direct current (DC) arc discharge method for the first time. The Bi@C nanocomposite without further decoration or any other treatment exhibits superior electrochemical performance as anode for SIBs and delivers stable capacities of 356, 342, 334, 327, 325, 323, and 318[Formula: see text]mA[Formula: see text]h[Formula: see text]g[Formula: see text] at the current densities of 0.2, 0.5, 1, 3, 5, 7 and 10[Formula: see text]A[Formula: see text]g[Formula: see text], respectively. There is no obvious decay after 630 cycles with a capacity of 291[Formula: see text]mA[Formula: see text]h[Formula: see text]g[Formula: see text] at 10[Formula: see text]A[Formula: see text]g[Formula: see text], showing the excellent rate capability and long cycle stability in SIBs. Electrochemical tests proved that the ultra-fast charge–discharge performance is related to the fast redox kinetics of Na[Formula: see text] in layered structure of bismuth crystal. The Na[Formula: see text] storage mechanism of Bi@C nanocomposite anode was also investigated by cyclic voltammetry and in situ XRD. Based on experimental data, this paper proves that the arc discharge method is a simple and efficient method for preparing nanoscale electrode materials.