Carbon encapsulated Sn-Co alloy: A stabilized tin-based material for sodium storage

• Published in: Materials letters 2018-01, Vol.210, p.321-324
• Main Authors: Huang, Bin, Yang, Jianwen, Li, Yanwei, Xiao, Shunhua, Chen, Quanqi
• Format: Article
• Language: English
• Subjects: Alloys; Carbon; Chemical elements; Cobalt base alloys; Diffraction; Diffusion; Encapsulation; Energy storage and conversion; Intermetallic; Kinetics; Materials science; Microstructure; Scanning electron microscopy; Sodium-ion battery; Synthesis; Tin base alloys; Tin-based material; X-ray diffraction
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2017.09.055

[Display omitted] •Carbon encapsulated Sn-Co alloy was designed and synthesized.•Sn-Co alloy core showed improved reversibility than pure Sn core.•Sn-Co alloy exhibited enhanced cycling stability and rate capability.•Cobalt acted as a stable and conductive matrix. A novel yolk-shell structure consisting of an intermetallic Sn-Co core, a carbon shell and void space between the core and shell has been designed and successfully synthesized. X-ray diffraction (XRD) measurements indicate that the core is SnCo alloy and the shell is amorphous. The yolk-shell structure is observed by scanning electron microscope (SEM). For comparison, carbon encapsulated pure Sn, which also possesses a yolk-shell structure, has been synthesized as well. Electrochemical characterizations reveal that the SnCo@C sample has significantly improved electrochemical reversibility, cycling stability and rate capability than Sn@C. The cobalt in the SnCo alloy is proved to play a critical role of conductive stable matrix to stabilize Sn during sodiation/desodiation process and facilitate the diffusion kinetics of sodium.