Uniform Nano-Sn/C Composite\nAnodes for Lithium Ion\nBatteries

Abstract

Nano-Sn/C composites are ideal anode materials for high\nenergy\nand power density Li-ion batteries. However, because of the low melting\npoint of Sn and the tendency of grain growth, especially during high\ntemperature carbonization, it has been a significant challenge to\ncreate well-dispersed ultrasmall Sn nanoparticles within a carbon\nmatrix. In this paper, we demonstrate an aerosol spray pyrolysis technique,\nas a facile and scalable method, to synthesize a nano-Sn/C composite\nwith uniformly dispersed 10 nm nano-Sn within a spherical carbon matrix.\nThe discharge capacity of nano-Sn/C composite sphere anodes maintains\nthe initial capacity of 710 mAh/g after 130 cycles at 0.25 C. The\nnano-Sn/C composite sphere anodes can provide ∼600 mAh/g even\nat a high rate of 20 C. To the best of our knowledge, such high rate\nperformance for Sn anodes has not been reported previously. The exceptional\nperformance of the nano-Sn/C composite is attributed to the unique\nnano-Sn/C structure: (1) carbon matrix offers mechanical support to\naccommodate the stress associated with the large volume change of\nnano-Sn, thus alleviating pulverization; (2) the carbon matrix prevents\nSn nanoparticle agglomeration upon prolonged cycling; and (3) carbon\nnetwork provides continuous path for Li ions and electrons inside\nthe nano-Sn/C composite spheres.