Tuning particle and phase formation of Sn/carbon nanofibers composite towards stable lithium-ion storage

摘要

Sn is an attractive anodic material for lithium-ion batteries. High-temperature reduction is large-scale technique since most elemental Sn exists in the form of oxides. However, it is still a challenge to fabricate high performance Sn-based anodes with well-dispersed Sn nanoparticles in conductive matrix due to low melting point of Sn and tendency of particle agglomeration. Herein, we systematically investigate the influences of reduction conditions on particle and phase formation of Sn/carbon nanofibers (CNF) from electrospun SnO2/polyacrylonitrile. It is shown that the SnO2 can be reduced to Sn with slight aggregation at low temperature of 500 degrees C in a reducing atmosphere, but the composites possess poor electronic conductivity. As raising temperature, the grain size of Sn increases accordingly leading to sluggish Li+ internal diffusion dynamics. While in an inert atmosphere, the SnO2 cannot be reduced completely at low temperature until 650 degrees C. By optimal control, the Sn/CNF-N-2-700 calcined at 700 degrees C in N-2 atmosphere presents the best electrochemical Li-ion storage performance among these samples, which delivers a reversible capacity of 932.2 mAh g(-1) at 100 mA g(-1 )and stable cycling life with 760.3 mAh g(-1) retention after 200 cycles. This study may provide optimization guidance for industrial manufacture of Sn-based materials.