Strategy for yolk-shell structured metal oxide-carbon composite powders and their electrochemical properties for lithium-ion batteries

• Published in: Carbon (New York) 2016-04, Vol.100, p.137-144
• Main Authors: Ju, Hyeon Seok, Hong, Young Jun, Cho, Jung Sang, Kang, Yun Chan
• Format: Article
• Language: English
• Subjects: Carbon composite; Lithium ion battery; Spray pyrolysis; Yolk-shell
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2016.01.008

A strategy for the preparation of metal oxide-carbon composite powders with yolk-shell structure by simple spray pyrolysis is introduced. Mn–Sn–O–C composite powders with yolk-shell structure representing the first target material are prepared by one-pot spray pyrolysis and their formation mechanism is evaluated. Phase separation of polyvinylpyrrolidone (PVP), Sn, and Mn components during the drying stage of droplets plays a key role in the formation of yolk-shell structured composite powders. The repeated combustion and contraction processes of the dried powders under N2 atmosphere produce the desired Mn–Sn–O–C composite powders with yolk-shell structure. The shell and core parts of the yolk-shell powders prepared directly by spray pyrolysis at 900 °C are MnO–Mn2SnO4–C and Sn–Mn2SnO4–C composites, respectively. The initial discharge capacities of the composite powders prepared at 700 and 900 °C at the current density of 1 A g−1 are 1058 and 1204 mA h g−1, respectively. The discharge capacities of the composite powders prepared at 900 °C for the 2nd and 100th cycle are 803 and 784 mA h g−1, respectively. The structural stability of the Mn–Sn–O–C composite powders with yolk-shell structure during cycling results in good electrochemical performance.