Mn_2SiO_4/CNT composites as anode materials for high performance lithium-ion batteries

摘要

Mn~(2)SiO~(4)/CNT composite, which is constructed with polyhedron-shaped particles embedded in the carbon nanotube (CNT) network, has been synthesized by a sol–gel method. The as-prepared Mn~(2)SiO~(4)presented a well-developed orthorhombic crystal structure, and after modified with CNT, the compound exhibited excellent rate capability and cyclic performance as anode materials for lithium ion batteries. Galvanostatic charge–discharge measurements demonstrated outstanding initial charge and discharge capacity of 664.8 and 392.1 mA h g_(−1)at the current density of 100 mA g_(−1), respectively, and stable reversible capacity of 466.9 mA h g_(−1)was retained after 40 cycles. Even at a high current density of 2000 mA g_(−1), Mn~(2)SiO~(4)/CNT can deliver the specific capacity of 205.8 mA h g_(−1). Also, the reaction mechanism of this material is speculated including the formation of Li~(2)SiO~(3), MnO and Mn. In addition, the significant change of charge transfer resistance compared with pristine Mn~(2)SiO~(4)confirmed by electrochemical impedance spectroscopy illustrated the fast Li ions intercalation kinetics and reduced electrochemical polarization via CNT modification, suggesting Mn~(2)SiO~(4)/CNT to be promising anode materials for high performance lithium ion batteries.